44 results on '"Lihong Huo"'
Search Results
2. 2001 α-ketoglutarate-dependent KDM6 histone demethylases epigenetically regulate Interferon Stimulated Gene expression in Lupus
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Janet Wei, C Noel Bairey Merz, Daniel J Wallace, Sarah Parker, Mariko Ishimori, Caroline Jefferies, Erica N Montano, Moumita Bose, Lihong Huo, Gantsetseg Tumurkhuu, Gabriela De Los Santos, Aleksandr B Stotland, Gislaine Martins, Sarfaraz Lalani, and Kate Lawrenson
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Immunologic diseases. Allergy ,RC581-607 - Published
- 2022
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3. Keratin 13 Is Enriched in Prostate Tubule-Initiating Cells and May Identify Primary Prostate Tumors that Metastasize to the Bone.
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Sandy Liu, Radu M Cadaneanu, Baohui Zhang, Lihong Huo, Kevin Lai, Xinmin Li, Colette Galet, Tristan R Grogan, David Elashoff, Stephen J Freedland, Matthew Rettig, William J Aronson, Beatrice S Knudsen, Michael S Lewis, and Isla P Garraway
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Medicine ,Science - Abstract
BACKGROUND:Benign human prostate tubule-initiating cells (TIC) and aggressive prostate cancer display common traits, including tolerance of low androgen levels, resistance to apoptosis, and microenvironment interactions that drive epithelial budding and outgrowth. TIC can be distinguished from epithelial and stromal cells that comprise prostate tissue via cell sorting based upon Epcam, CD44, and CD49f antigenic profiles. Fetal prostate epithelial cells (FC) possess a similar antigenic profile to adult TIC and are capable of inducing tubule formation. To identify the TIC niche in human prostate tissue, differential keratin (KRT) expression was evaluated. RESULTS:Gene expression data generated from Affymetrix Gene Chip human U133 Plus 2.0 array of sorted adult and fetal epithelial cells revealed KRT13 to be significantly enriched in FC and TIC compared to basal cells (BC) and luminal cells (LC) (p
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- 2016
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4. Somato-dendritic localization and signaling by leptin receptors in hypothalamic POMC and AgRP neurons.
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Sangdeuk Ha, Scott Baver, Lihong Huo, Adriana Gata, Joyce Hairston, Nicholas Huntoon, Wenjing Li, Thompson Zhang, Elizabeth J Benecchi, Maria Ericsson, Shane T Hentges, and Christian Bjørbæk
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Medicine ,Science - Abstract
Leptin acts via neuronal leptin receptors to control energy balance. Hypothalamic pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP)/Neuropeptide Y (NPY)/GABA neurons produce anorexigenic and orexigenic neuropeptides and neurotransmitters, and express the long signaling form of the leptin receptor (LepRb). Despite progress in the understanding of LepRb signaling and function, the sub-cellular localization of LepRb in target neurons has not been determined, primarily due to lack of sensitive anti-LepRb antibodies. Here we applied light microscopy (LM), confocal-laser scanning microscopy (CLSM), and electron microscopy (EM) to investigate LepRb localization and signaling in mice expressing a HA-tagged LepRb selectively in POMC or AgRP/NPY/GABA neurons. We report that LepRb receptors exhibit a somato-dendritic expression pattern. We further show that LepRb activates STAT3 phosphorylation in neuronal fibers within several hypothalamic and hindbrain nuclei of wild-type mice and rats, and specifically in dendrites of arcuate POMC and AgRP/NPY/GABA neurons of Leprb (+/+) mice and in Leprb (db/db) mice expressing HA-LepRb in a neuron specific manner. We did not find evidence of LepRb localization or STAT3-signaling in axon-fibers or nerve-terminals of POMC and AgRP/NPY/GABA neurons. Three-dimensional serial EM-reconstruction of dendritic segments from POMC and AgRP/NPY/GABA neurons indicates a high density of shaft synapses. In addition, we found that the leptin activates STAT3 signaling in proximity to synapses on POMC and AgRP/NPY/GABA dendritic shafts. Taken together, these data suggest that the signaling-form of the leptin receptor exhibits a somato-dendritic expression pattern in POMC and AgRP/NPY/GABA neurons. Dendritic LepRb signaling may therefore play an important role in leptin's central effects on energy balance, possibly through modulation of synaptic activity via post-synaptic mechanisms.
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- 2013
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5. Correction: Somato-Dendritic Localization and Signaling by Leptin Receptors in Hypothalamic POMC and AgRP Neurons.
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Sangdeuk Ha, Scott Baver, Lihong Huo, Adriana Gata, Joyce Hairston, Nicholas Huntoon, Wenjing Li, Thompson Zhang, Elizabeth J. Benecchi, Maria Ericsson, Shane T. Hentges, and Christian Bjørbæk
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Medicine ,Science - Published
- 2013
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6. Systematic Analysis of the Functions of Lysine Acetylation in the Regulation of Tat Activity.
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Minghao He, Linlin Zhang, Xincheng Wang, Lihong Huo, Lei Sun, Chengye Feng, Xutian Jing, Danyao Du, Huabin Liang, Min Liu, Zhangyong Hong, and Jun Zhou
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Medicine ,Science - Abstract
The Tat protein of HIV-1 has several well-known properties, such as nucleocytoplasmic trafficking, transactivation of transcription, interaction with tubulin, regulation of mitotic progression, and induction of apoptosis. Previous studies have identified a couple of lysine residues in Tat that are essential for its functions. In order to analyze the functions of all the lysine residues in Tat, we mutated them individually to alanine, glutamine, and arginine. Through systematic analysis of the lysine mutants, we discovered several previously unidentified characteristics of Tat. We found that lysine acetylation could modulate the subcellular localization of Tat, in addition to the regulation of its transactivation activity. Our data also revealed that lysine mutations had distinct effects on microtubule assembly and Tat binding to bromodomain proteins. By correlation analysis, we further found that the effects of Tat on apoptosis and mitotic progression were not entirely attributed to its effect on microtubule assembly. Our findings suggest that Tat may regulate diverse cellular activities through binding to different proteins and that the acetylation of distinct lysine residues in Tat may modulate its interaction with various partners.
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- 2013
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7. Over-expression of leptin receptors in hypothalamic POMC neurons increases susceptibility to diet-induced obesity.
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Kevin M Gamber, Lihong Huo, Sangdeuk Ha, Joyce E Hairston, Sarah Greeley, and Christian Bjørbæk
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Medicine ,Science - Abstract
Diet-induced obesity (DIO) in rodents is characterized by impaired activation of signal-transducer and activator of transcription 3 (STAT3) by leptin receptors (LepRb) within the hypothalamic arcuate nucleus. This signaling defect likely plays an important role in development of DIO. However, the neuro-chemical identity of the leptin-STAT3 resistant arcuate neurons has not been determined and the underlying mechanisms responsible for development of cellular leptin resistance remain unclear. To investigate this, we first measured arcuate gene expression of known key signaling components of the LepRb signaling pathway and tested whether specifically the critical arcuate pro-opiomelanocortin (POMC) neurons are resistant to LepRb-STAT3 signaling in mice given a high-fat-diet (HFD) compared to mice provided a low-fat control diet (LFD). We found that leptin-dependent STAT3 phosphorylation was decreased within POMC neurons of HFD mice. In addition, Leprb mRNA and suppressor of cytokine signaling 3 (Socs3) mRNA were elevated in the arcuate of HFD mice. To investigate whether increased LepRb expression per se in POMC neurons can influence development of DIO and Socs3 expression, we created mice that over-express LepRb selectively in POMC neurons (POMC-LepRb). No differences in body weight, fat mass or food intake were found between LFD POMC-LepRb mice and LFD controls. Surprisingly, body weight, fat mass and caloric intake of HFD POMC-LepRb mice was markedly higher than HFD control mice. In addition, arcuate Socs3 mRNA was increased in HFD POMC-LepRb mice compared to HFD controls. These data show that specifically POMC neurons of DIO mice are resistant to STAT3 activation by leptin, indicating that those cells might play a role in development of DIO. Furthermore, over-expression of LepRb selectively in POMC neurons increases susceptibility to the development of DIO. We propose a model where over-reactivity of the leptin-LepRb signaling system in arcuate neurons may play causal a role in development of diet-induced obesity.
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- 2012
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8. Macrophage fumarate hydratase restrains mtRNA-mediated interferon production
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Alexander Hooftman, Christian G. Peace, Dylan G. Ryan, Emily A. Day, Ming Yang, Anne F. McGettrick, Maureen Yin, Erica N. Montano, Lihong Huo, Juliana E. Toller-Kawahisa, Vincent Zecchini, Tristram A. J. Ryan, Alfonso Bolado-Carrancio, Alva M. Casey, Hiran A. Prag, Ana S. H. Costa, Gabriela De Los Santos, Mariko Ishimori, Daniel J. Wallace, Swamy Venuturupalli, Efterpi Nikitopoulou, Norma Frizzell, Cecilia Johansson, Alexander Von Kriegsheim, Michael P. Murphy, Caroline Jefferies, Christian Frezza, and Luke A. J. O’Neill
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Multidisciplinary - Abstract
Metabolic rewiring underlies the effector functions of macrophages 1–3, but the mechanisms involved remain incompletely defined. Here, using unbiased metabolomics and stable isotope-assisted tracing, we show that an inflammatory aspartate–argininosuccinate shunt is induced following lipopolysaccharide stimulation. The shunt, supported by increased argininosuccinate synthase (ASS1) expression, also leads to increased cytosolic fumarate levels and fumarate-mediated protein succination. Pharmacological inhibition and genetic ablation of the tricarboxylic acid cycle enzyme fumarate hydratase (FH) further increases intracellular fumarate levels. Mitochondrial respiration is also suppressed and mitochondrial membrane potential increased. RNA sequencing and proteomics analyses demonstrate that there are strong inflammatory effects resulting from FH inhibition. Notably, acute FH inhibition suppresses interleukin-10 expression, which leads to increased tumour necrosis factor secretion, an effect recapitulated by fumarate esters. Moreover, FH inhibition, but not fumarate esters, increases interferon-β production through mechanisms that are driven by mitochondrial RNA (mtRNA) release and activation of the RNA sensors TLR7, RIG-I and MDA5. This effect is recapitulated endogenously when FH is suppressed following prolonged lipopolysaccharide stimulation. Furthermore, cells from patients with systemic lupus erythematosus also exhibit FH suppression, which indicates a potential pathogenic role for this process in human disease. We therefore identify a protective role for FH in maintaining appropriate macrophage cytokine and interferon responses.
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- 2023
9. 2001 α-ketoglutarate-dependent KDM6 histone demethylases epigenetically regulate Interferon Stimulated Gene expression in Lupus
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Erica N Montano, Moumita Bose, Lihong Huo, Gantsetseg Tumurkhuu, Gabriela De Los Santos, Aleksandr B Stotland, Janet Wei, C Noel Bairey Merz, Gislaine Martins, Sarfaraz Lalani, Kate Lawrenson, Sarah Parker, Mariko Ishimori, Daniel J Wallace, and Caroline Jefferies
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- 2022
10. County Median Family Income Is an Independent Prognostic Factor for Stage IV Anaplastic Thyroid Cancer
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Nitin Trivedi, Pengyang Li, Ying Ning, Ahmad Daniyal Siddiqui, Rui Mao, M U Li, Lihong Huo, and Sophi Gu
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Male ,Oncology ,Cancer Research ,medicine.medical_specialty ,Multivariate statistics ,Multivariate analysis ,Thyroid Gland ,Family income ,Thyroid Carcinoma, Anaplastic ,Malignancy ,Disease-Free Survival ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Humans ,Thyroid Neoplasms ,Anaplastic thyroid cancer ,Socioeconomic status ,Aged ,Neoplasm Staging ,Retrospective Studies ,Aged, 80 and over ,Univariate analysis ,business.industry ,Univariate ,General Medicine ,Middle Aged ,Prognosis ,medicine.disease ,United States ,030220 oncology & carcinogenesis ,Multivariate Analysis ,Income ,Thyroidectomy ,Female ,business ,SEER Program - Abstract
Background/aim Advanced anaplastic thyroid cancer (ATC) is a rare, but highly aggressive malignancy, and its prognostic factors need to be further explored. We examined socioeconomic factors' predictive effect for survival performance in stage IV ATC patients. Materials and methods Using the Surveillance, Epidemiology, and End Results database, we collected 1,048 cases with stage IV anaplastic thyroid cancer (ATC) from 2004 to 2015. Demographic, clinical, and socioeconomic factors were evaluated using univariate and multivariate analyses. Results Median family income showed a significant effect on overall survival (OS) and cancer-specific survival (CSS) in univariate analysis. Median family income level was found to be an independent prognostic factor for OS after multivariate adjustment Multivariate analysis for CSS showed similar results. Conclusion Family income level is an independent prognostic factor for stage IV ATC.
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- 2019
11. LncRNA MALAT1 regulates smooth muscle cell phenotype switch via activation of autophagy
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Liwen Huang, Hao Zhou, Wenjian Ma, Tie-Feng Song, Tong-Cun Zhang, Huiqin Wang, Ying Yuan, Lihong Huo, Hongpeng He, and Nan Wang
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0301 basic medicine ,autophagy ,Gene knockdown ,Vascular smooth muscle ,biology ,Chemistry ,Cellular differentiation ,Autophagy ,miR142-3p ,phenotype switching ,Phenotype ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Oncology ,Downregulation and upregulation ,030220 oncology & carcinogenesis ,Gene expression ,biology.protein ,vascular smooth muscle cells ,MALAT1 ,Platelet-derived growth factor receptor ,Research Paper - Abstract
Vascular smooth muscle cells (VSMCs), switching from a differentiated to a proliferative phenotype, contribute to various vascular diseases. However, the role of long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 MALAT1 in the phenotype switching of VSMCs remains unclear. Here, we report that the knockdown of MALAT1 promotes the transformation of smooth muscle cells from a proliferative phenotype to a differentiated phenotype. MALAT1 knockdown inhibited cellular proliferation and migration, leading to significant cell cycle arrest in the G2 phase. MALAT1 was downregulated in bone morphogenetic protein-7 (BMP-7)-induced cellular differentiation, while MALAT1 was upregulated in platelet-derived growth factor-BB (PDGF-BB)-induced cellular proliferation. PDGF induced the transformation of smooth muscle cells into a proliferative phenotype accompanied by an increase in autophagy. The downregulation of MALAT1 attenuated PDGF-BB-induced proliferation and migration by inhibiting autophagy. MALAT1 could act as a competing endogenous RNA (ceRNA) to regulate autophagy-related 7 (ATG7) gene expression by sponging miR142-3p. The present study reveals a novel mechanism by which MALAT1 promotes the transformation of smooth muscle cells from contraction to synthetic phenotypes.
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- 2017
12. miR-219a-5p inhibits breast cancer cell migration and epithelial-mesenchymal transition by targeting myocardin-related transcription factor A
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Ying Yuan, Tong-Cun Zhang, Huiqin Wang, Hao Zhou, Chun-Yu Zhuang, Nan Wang, Hongpeng He, Tie-Feng Song, Lihong Huo, Xue-Gang Luo, and Liwen Huang
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0301 basic medicine ,Epithelial-Mesenchymal Transition ,Biophysics ,Breast Neoplasms ,Vimentin ,Biochemistry ,03 medical and health sciences ,Breast cancer ,Cell Movement ,microRNA ,medicine ,Humans ,Genes, Tumor Suppressor ,Epithelial–mesenchymal transition ,Neoplasm Metastasis ,Transcription factor ,Gene knockdown ,biology ,Cell migration ,Hep G2 Cells ,General Medicine ,medicine.disease ,MicroRNAs ,030104 developmental biology ,Myocardin ,MCF-7 Cells ,Trans-Activators ,biology.protein ,Cancer research ,Female - Abstract
Although many miRNAs are reported to be involved in tumor formation and progression, the effect of miR-219a-5p on breast cancer metastasis is not well-known. The aim of this study is to investigate the effect of miR-219a-5p on the migratory ability and epithelial-mesenchymal transition (EMT) of breast cancer cells. First, miR-219a-5p was found to be highly expressed in low-invasive breast cancer MCF-7 cells, but lowly expressed in high-invasive breast cancer MDA-MB-231 cells. Wound scratch assay and transwell assay showed that miR-219a-5p inhibited the migratory ability of MDA-MB-231 cells. miR-219a-5p also suppressed the cellular EMT, confirmed by suppressing the expression of mesenchymal markers vimentin and N-cadherin and increasing the expression of epithelial marker E-cadherin. Using the epithelial-mesenchymal-epithelial model in MCF-7 cells, we confirmed that the level of miR-219a-5p was highly expressed in epithelial-type cells and lowly expressed in mesenchymal-type cells. Importantly, we identified myocardin-related transcription factor A (MRTF-A) as a novel potential target gene of miR-219a-5p. Overexpression of miR-219a-5p in MDA-MB-231 cells could inhibit the expression of MRTF-A as revealed by real-time PCR and western blot analysis. miR-219a-5p inhibited the transcription of MRTF-A by targeting the 3'UTR of MRTF-A, which was confirmed by wild-type or mutant MRTF-A 3'UTR luciferase reporter system. Furthermore, knockdown of MRTF-A using siRNA for MRTF-A could depress breast cell migration. In conclusion, our present study revealed the tumor suppressive role of miR-219a-5p in regulating breast cancer migration by targeting MRTF-A, suggesting that miR-219a-5p might be a therapeutic target in breast cancer through regulating EMT.
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- 2017
13. DOES T STAGE AFFECT PROGNOSIS IN PATIENTS WITH STAGE IV B DIFFERENTIATED THYROID CANCER?
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Mu Li, Yuning Wang, Ying Ning, Ahmad Daniyal Siddiqui, Sophie Z. Gu, Rui Mao, Nitin Trivedi, Lihong Huo, and Chenyang Dai
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Oncology ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,030209 endocrinology & metabolism ,Papillary thyroid cancer ,Thyroid carcinoma ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Internal medicine ,medicine ,Humans ,030212 general & internal medicine ,Thyroid Neoplasms ,Follicular thyroid cancer ,Thyroid cancer ,Neoplasm Staging ,Univariate analysis ,business.industry ,Hazard ratio ,Cancer ,General Medicine ,medicine.disease ,Prognosis ,T-stage ,Lymph Nodes ,business - Abstract
Objective: Differentiated thyroid cancer (DTC), the most common subtype of thyroid cancer, has a relatively good prognosis. The 8th edition of the American Joint Committee on Cancer (AJCC) pathologic tumor-node-metastasis (T [primary tumor size], N [regional lymph nodes], M [distant metastasis]) staging system did not take the T stage into consideration in stage IV B DTC patients. We evaluated the prognostic value of the T stage for advanced DTC survival. Methods: DTC cases that were considered stage IV B in the AJCC 8th edition were extracted from the Surveillance, Epidemiology, and End Results database. T stage (AJCC 6th standard) was categorized into T0-2, T3 and T4. We analyzed overall survival (OS) and cancer specific survival (CSS) in the overall group as well as in pathologic subgroups. We used the Kaplan-Meier method and log-rank test for univariate analysis and the Cox regression model for multivariate analysis. Results: A total of 519 cases were extracted. Patients with earlier T stages showed significantly better OS and CSS in univariate analysis. T stage was an independent prognostic factor for both OS and CSS in multivariate analysis. Subgroup analysis in papillary and follicular thyroid cancer showed that T4 was an independent prognostic factor for both OS and CSS. Conclusion: AJCC 8 stage IV B DTC patients could be further stratified by T stage. Further studies with larger samples and AJCC 8 T stage information are necessary. Abbreviations: AJCC = American Joint Committee on Cancer; CI = confidence interval; CSS = cancer specific survival; DTC = differentiated thyroid cancer; FTC = follicular thyroid cancer; FVPTC = follicular variant of papillary thyroid carcinoma; HR = hazard ratio; OS = overall survival; PTC = papillary thyroid cancer; SEER = surveillance, epidemiology, and end results database.
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- 2019
14. Synthesis and Biological Evaluations of Cytotoxic and Antiangiogenic Triterpenoids-Jacaranone Conjugates
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Ole Lund, Olivier Taboureau, Shao Rong Wang, Wei-Shuo Fang, Ying Zhao, Ricky N S Wong, Hua Sun, Lihong Huo, Partick Y. K. Yue, Songbo Xie, Jun Zhou, and Jens Vindahl Kringelum
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Male ,Angiogenesis Inhibitors ,Antineoplastic Agents ,Aorta, Thoracic ,Pharmacology ,Rats, Sprague-Dawley ,Structure-Activity Relationship ,chemistry.chemical_compound ,0404 agricultural biotechnology ,Cell Line, Tumor ,Drug Discovery ,Benzoquinones ,Human Umbilical Vein Endothelial Cells ,medicine ,Animals ,Humans ,Structure–activity relationship ,Cytotoxic T cell ,Interferon gamma ,Oleanolic Acid ,Cytotoxicity ,Oleanolic acid ,biology ,Chemistry ,Rational design ,04 agricultural and veterinary sciences ,040401 food science ,Triterpenes ,Cell culture ,Microvessels ,biology.protein ,Drug Screening Assays, Antitumor ,Neuraminidase ,medicine.drug - Abstract
Background: The development of antiangiogenic agents arises as a more effective and selective therapeutic approach for the treatment of cancer. In addition to reduced acute toxicity, the efficacy of chemotherapy could be improved when administered in combination specific antiangiogenic with cytotoxic agents. The conjugation or hybridization of bifunctional molecules is one of the alternative rational design strategies for co-administration of anticancer drugs. Objective and Methods: The goal of this work is to prepare the conjugates of an antiangiogenic triterpene, 3-oxo oleanolic acid, and structurally related triterpenoids with a cytotoxic semibenzoquinone, jacaranone. The cytotoxic, antiproliferative and antiangiogenic activities of segments and conjugates were determined. The possible targets of conjugates 6a-6h were predicted using Similarity Ensemble Approach (SEA). Results: The results showed that these conjugates are more potent in both cytotoxic and antiangiogenic assays than their corresponding parent molecules, and are also selectively more active against melanoma cells B16 and metastatic B16BL6 than the two other cancer cell lines (A549 and MCF-7) tested. The predicted antiangiogenesis related targets could involve glycogen phosphorylase, neuraminidase, interferon gamma, and tubulin beta chain. Conclusion: The bifunctional conjugates could be useful as dual acting antitumor/antigiogenic agents.
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- 2016
15. Abstract P6-03-16: Role of autophagy in CD24-mediated TNBC drug resistance
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Xinyu Deng, Xiang Huang, Helena R. Chang, and Lihong Huo
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Cancer Research ,biology ,business.industry ,CD24 ,CD44 ,Autophagy ,Cancer ,medicine.disease ,Small hairpin RNA ,Oncology ,Docetaxel ,biology.protein ,Cancer research ,Medicine ,skin and connective tissue diseases ,business ,Protein kinase B ,PI3K/AKT/mTOR pathway ,medicine.drug - Abstract
Background: Triple-negative breast cancer (TNBC) is defined by lack of estrogen and progesterone receptors and absence of HER2 amplification. Compared with other breast cancer subtypes, TNBC is more aggressive with more frequent metastasis especially involving visceral and central nervous system. Currently, the only available standard adjuvant treatment is chemotherapy. However, mortality rate remains high despite chemotherapy. To improve treatment, it is crucial to develop novel strategies to predict and overcome drug resistance. Our pervious study showed that CD44/CD24 expressions were associated with drug sensitivity and CD44+/CD24+ TNBC was shown to be resistant to docetaxel. In this study, we aimed to investigate the regulatory mechanism involved in CD24-mediated taxane resistance in TNBC. Methods: In this study, we used flow cytometry to determine the CD24 expressions in 7 TNBC cell lines. Western blot was used to demonstrate the levels of CD24 and LC3B-II (a marker for cellular autophagy activity) expressions in TNBC cell lines. CD24 expressions in TNBC cell lines were manipulated by target-specific shRNA and gene overexpression approaches. Cell apoptosis assay was used to determine docetaxel drug sensitivity in cells with manipulated CD24 expression. Using the same assay, autophagy inhibitors were used to further evaluate the involvement of autophagy in CD24-mediated drug resistance. To investigate the possible regulatory mechanism, autophagy related signaling pathway Akt/mTOR was studied in CD24 modified TNBC cells. Results: In this study, the relationship between CD24 expression and autophagy activities in TNBC was evaluated. LC3B-II protein expression was used to determinate autophagy activities. We have shown that TNBC cell lines with high CD24 expressions are associated with increased LC3B-II expression. Suppression of autophagy in CD24 high TNBC cells improves drug sensitivities toward docetaxel. We further demonstrated that knocking down CD24 in TNBC cells suppressed LC3B-II expression and improved docetaxel sensitivity. In addition, gene overexpression of CD24was found to enhance docetaxel resistance in TNBC cells. Our study has also shown that docetaxel increases the activation of Akt/mTOR signaling pathway in drug-resistant TNBC cells. Knocking down CD24 increased Akt/mTOR activation, and decreased the expression of PP2A and LC3B-II in TNBC. Conclusions: CD24 expression is associated with docetaxel sensitivity and autophagy activity in TNBC cells. Drug sensitivity of CD44+CD24+/high TNBC cells is regulated through autophagy related signaling pathway. Taken together, CD24 mediated TNBC drug resistance is at least partially through autophagy activity. Citation Format: Lihong Huo, Xinyu Deng, Xiang Huang, Helena R Chang. Role of autophagy in CD24-mediated TNBC drug resistance [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-03-16.
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- 2020
16. Overexpression of Hdac6 enhances resistance to virus infection in embryonic stem cells and in mice
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Li Zhiguo, Jianchao Wang, Dekun Wang, Meng Yang, Qingwen Meng, Lihong Huo, Lingling Wang, Li Qiuyan, Na Liu, Xinyu Chen, Hongsheng Ouyang, Ning Li, Lingyi Chen, Jun Zhou, Zhen Dai, Lin Liu, and Xiaoying Ye
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Mice, Knockout ,Regulation of gene expression ,Letter ,Cell Biology ,HDAC6 ,Biology ,Histone Deacetylase 6 ,Infections ,Biochemistry ,Molecular biology ,Embryonic stem cell ,Gene Expression Regulation, Enzymologic ,Histone Deacetylases ,Virus ,Mice ,Drug Discovery ,Animals ,Stem cell ,H5N1 virus ,Developmental biology ,Embryonic Stem Cells ,Biotechnology - Published
- 2014
17. Selective p300 inhibitor C646 inhibited HPV E6-E7 genes, altered glucose metabolism and induced apoptosis in cervical cancer cells
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Yongwei Lai, Yupeng Liu, Xiang Liu, Chenhong Guo, Yunpeng Hao, Tong-Cun Zhang, Lihong Huo, Mengmeng Zhang, Wenjian Ma, Hao Zhou, Xue-Gang Luo, Hongpeng He, Zijiang Zhang, and Nan Wang
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0301 basic medicine ,Papillomavirus E7 Proteins ,Uterine Cervical Neoplasms ,Apoptosis ,Biology ,Benzoates ,03 medical and health sciences ,Transcription (biology) ,medicine ,Humans ,Glycolysis ,Enzyme Inhibitors ,Pyrazolones ,Gene ,Nitrobenzenes ,Cell Proliferation ,Pharmacology ,Cervical cancer ,Membrane Potential, Mitochondrial ,Glucose Transporter Type 1 ,Dose-Response Relationship, Drug ,Cell growth ,Oncogene Proteins, Viral ,medicine.disease ,Molecular biology ,Phenotype ,Gene Expression Regulation, Neoplastic ,Repressor Proteins ,030104 developmental biology ,Glucose ,Cancer cell ,Pyrazoles ,Female ,E1A-Associated p300 Protein ,HeLa Cells - Abstract
High risk HPV infection is a causative factor of cervical cancer. The constitutive expression of HPV E6-E7 genes is important for the maintenance of cancer phenotypes. The cellular transcription co-activator p300 plays a crucial role in the regulation of HPV genes thus it was targeted for the inhibition of HPV-associated cervical cancer. In the present study, HPV positive cervical cells were treated with C646, a selective inhibitor of p300, to investigate its influence on HPV E6-E7 expression and cancer cell growth. Results of RT-qPCR, Western-blot and promoter activity assays showed that C646 inhibited the transcription of HPV E6-E7, which was accompanied with the accumulation of p53 protein. Meanwhile, cell proliferation was suppressed, glucose metabolism was disrupted and apoptosis was induced via the intrinsic pathway. Generally, the anti-cervical cancer potential of C646 was demonstrated and a novel mechanism was proposed in this study.
- Published
- 2017
18. Modulation of Eg5 activity contributes to mitotic spindle checkpoint activation and Tat-mediated apoptosis in CD4-positive T-lymphocytes
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Xiaodong Sun, Linlin Zhang, Min Liu, Jun Zhou, Jie Chen, Lei Sun, Dengwen Li, and Lihong Huo
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Motor protein ,Spindle checkpoint ,Transactivation ,Apoptosis ,Regulator ,Biology ,Mitotic spindle checkpoint ,Mitosis ,Pathology and Forensic Medicine ,Spindle apparatus ,Cell biology - Abstract
Tat, the transactivation factor of human immunodeficiency virus type 1 (HIV-1), represents one of the major players mediating the loss of CD4-positive T-lymphocytes in HIV-1-infected patients, primarily due to the ability of Tat to trigger apoptosis. However, the molecular events underlying this process remain elusive. In this study, we provide evidence that Tat interacts with Eg5, a microtubule-associated motor protein, and allosterically modulates the ATPase activity of Eg5 by affecting ADP release from the enzyme's active centre. This action of Tat impairs the formation of the mitotic spindle and activates the spindle checkpoint, thereby blocking cell cycle progression at mitosis and leading to apoptosis. Further studies reveal that lysine 85 in the carboxyl terminus of Tat is critical for its interaction with Eg5 and hence its effects on Eg5 activity, mitotic progression, and apoptosis. These findings identify Tat as a viral regulator of Eg5 and provide novel insights into the mechanisms of action of Tat in mediating the reduction of CD4-positive T-lymphocytes.
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- 2014
19. Keratin 13 Is Enriched in Prostate Tubule-Initiating Cells and May Identify Primary Prostate Tumors that Metastasize to the Bone
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Xin-Min Li, Colette Galet, Tristan Grogan, Baohui Zhang, Matthew Rettig, Beatrice S. Knudsen, Stephen J. Freedland, Kevin Lai, Isla P. Garraway, Sandy T. Liu, William J. Aronson, Lihong Huo, Radu M. Cadaneanu, Michael S. Lewis, David Elashoff, and Samant, Rajeev
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0301 basic medicine ,Keratinocytes ,Male ,Pathology ,Cellular differentiation ,Biopsy ,Gene Expression ,lcsh:Medicine ,Immunostaining ,Pathology and Laboratory Medicine ,Epithelium ,Prostate cancer ,Mice ,Prostate ,Animal Cells ,Stem Cell Research - Nonembryonic - Human ,Medicine and Health Sciences ,Needle ,Reproductive System Procedures ,lcsh:Science ,Cancer ,Staining ,Multidisciplinary ,Tissue microarray ,biology ,Prostate Cancer ,Biopsy, Needle ,Prostate Diseases ,Cell Differentiation ,Basal Cells ,Radical Prostatectomy ,Gene Expression Regulation, Neoplastic ,medicine.anatomical_structure ,Oncology ,Neoplastic Stem Cells ,Anatomy ,Cellular Types ,Research Article ,Biotechnology ,PCA3 ,Adult ,Urologic Diseases ,medicine.medical_specialty ,Stromal cell ,General Science & Technology ,Urology ,Surgical and Invasive Medical Procedures ,Bone Neoplasms ,Research and Analysis Methods ,03 medical and health sciences ,Exocrine Glands ,Signs and Symptoms ,Diagnostic Medicine ,medicine ,Genetics ,Animals ,Humans ,Prostatectomy ,Neoplastic ,Surgical Excision ,CD44 ,lcsh:R ,Keratin-13 ,Biology and Life Sciences ,Cancers and Neoplasms ,Prostatic Neoplasms ,Epithelial Cells ,Cell Biology ,medicine.disease ,Stem Cell Research ,Survival Analysis ,Genitourinary Tract Tumors ,030104 developmental biology ,Biological Tissue ,Gene Expression Regulation ,Specimen Preparation and Treatment ,biology.protein ,Lesions ,Prostate Gland ,lcsh:Q - Abstract
Author(s): Liu, Sandy; Cadaneanu, Radu M; Zhang, Baohui; Huo, Lihong; Lai, Kevin; Li, Xinmin; Galet, Colette; Grogan, Tristan R; Elashoff, David; Freedland, Stephen J; Rettig, Matthew; Aronson, William J; Knudsen, Beatrice S; Lewis, Michael S; Garraway, Isla P | Abstract: BackgroundBenign human prostate tubule-initiating cells (TIC) and aggressive prostate cancer display common traits, including tolerance of low androgen levels, resistance to apoptosis, and microenvironment interactions that drive epithelial budding and outgrowth. TIC can be distinguished from epithelial and stromal cells that comprise prostate tissue via cell sorting based upon Epcam, CD44, and CD49f antigenic profiles. Fetal prostate epithelial cells (FC) possess a similar antigenic profile to adult TIC and are capable of inducing tubule formation. To identify the TIC niche in human prostate tissue, differential keratin (KRT) expression was evaluated.ResultsGene expression data generated from Affymetrix Gene Chip human U133 Plus 2.0 array of sorted adult and fetal epithelial cells revealed KRT13 to be significantly enriched in FC and TIC compared to basal cells (BC) and luminal cells (LC) (pl0.001). Enriched KRT13 expression was confirmed by RT-PCR and cytospin immunostaining. Immunohistochemical analysis of KRT13 expression revealed rare KRT13+ epithelia throughout prostatic ducts/acini in adult tissue specimens and differentiated tubules in 24-week recombinant grafts, In contrast, abundant KRT13 expression was observed in developing ducts/acini in fetal prostate and cord-like structures composing 8-week recombinant grafts. Immunostaining of a prostate tissue microarray revealed KRT13+ tumor foci in approximately 9% of cases, and this subset displayed significantly shorter time to recurrence (p = 0.031), metastases (p = 0.032), and decreased overall survival (p = 0.004). Diagnostic prostate needle biopsies (PNBX) from untreated patients with concurrent bone metastases (clinical stage M1) displayed KRT13+ tumor foci, as did bone metastatic foci.ConclusionsThe expression profile of KRT13 in benign fetal and adult prostate tissue and in recombinant grafts, as well as the frequency of KRT13 expression in primary and metastatic prostate cancer indicates that it may be a marker of a stem/progenitor-like cell state that is co-opted in aggressive tumor cells. KRT13 is enriched in benign stem-like cells that display androgen-resistance, apoptosis-resistance, and branching morphogenesis properties. Collectively our data demonstrate that KRT13 expression is associated with poor prognosis at multiple stages of disease progression and may represent an important biomarker of adverse outcome in patients with prostate cancer.
- Published
- 2016
20. PGC-1α Controls Skeletal Stem Cell Fate and Bone-Fat Balance in Osteoporosis and Skeletal Aging by Inducing TAZ
- Author
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Lihong Huo, Christine Hong, Jiong Li, Peng Deng, Cun-Yu Wang, John M. Szymanski, Bo Yu, Xianghang Luo, Yunsong Liu, and Jiandie D. Lin
- Subjects
Male ,TAZ ,0301 basic medicine ,Aging ,Osteoporosis ,PDZ Domains ,PGC-1α ,Adipose tissue ,Inbred C57BL ,Regenerative Medicine ,bone ,Medical and Health Sciences ,Mice ,fat ,80 and over ,Aged, 80 and over ,Mice, Knockout ,Stem Cells ,Intracellular Signaling Peptides and Proteins ,Adaptor Proteins ,Skeletal ,Biological Sciences ,Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha ,Cell biology ,Adipose Tissue ,Adipogenesis ,Muscle ,Molecular Medicine ,Female ,Stem Cell Research - Nonembryonic - Non-Human ,Stem cell ,Adult ,Knockout ,Cell fate determination ,Biology ,Bone and Bones ,Article ,Bone resorption ,Young Adult ,03 medical and health sciences ,Coactivator ,Genetics ,medicine ,Animals ,Humans ,Muscle, Skeletal ,Adaptor Proteins, Signal Transducing ,Aged ,mesenchymal stem cells ,Mesenchymal stem cell ,Signal Transducing ,Cell Biology ,Stem Cell Research ,medicine.disease ,osteoporosis ,Mice, Inbred C57BL ,030104 developmental biology ,skeletal stem cells ,Transcriptional Coactivator with PDZ-Binding Motif Proteins ,lineage decision ,Musculoskeletal ,Trans-Activators ,Transcription Factors ,Developmental Biology - Abstract
Aberrant lineage specification of skeletal stem cells (SSCs) contributes to reduced bone mass and increased marrow adipose tissue (MAT) in osteoporosis and skeletal aging. Although master regulators of osteoblastic and adipogenic lineages have been identified, little is known about factors that are associated with MAT accumulation and osteoporotic bone loss. Here, we identify peroxisome-proliferator-activated receptor γ coactivator 1-α (PGC-1α) as a critical switch of cell fate decisions whose expression decreases with aging in human and mouse SSCs. Loss of PGC-1α promoted adipogenic differentiation of murine SSCs at the expense of osteoblastic differentiation. Deletion ofPGC-1α in SSCs impaired bone formation andindirectly promoted bone resorption while enhancing MAT accumulation. Conversely, induction of PGC-1α attenuated osteoporotic bone loss and MAT accumulation. Mechanistically, PGC-1α maintains bone and fat balance by inducing TAZ. Our results suggest that PGC-1α is a potentially important therapeutic target in the treatment of osteoporosis and skeletal aging.
- Published
- 2018
21. CYLD regulates angiogenesis by mediating vascular endothelial cell migration
- Author
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Jinmin Gao, Lei Sun, Jun Zhou, Lihong Huo, Min Liu, and Dengwen Li
- Subjects
rac1 GTP-Binding Protein ,Endothelium ,Angiogenesis ,Immunoblotting ,Immunology ,Mice, Nude ,Neovascularization, Physiologic ,RAC1 ,Biology ,Biochemistry ,Neovascularization ,Mice ,Cell Movement ,medicine ,Animals ,Humans ,Cells, Cultured ,Tube formation ,Wound Healing ,Matrigel ,Tumor Suppressor Proteins ,Cell migration ,Cell Biology ,Hematology ,Deubiquitinating Enzyme CYLD ,Cell biology ,Endothelial stem cell ,medicine.anatomical_structure ,Microscopy, Fluorescence ,Endothelium, Vascular ,medicine.symptom - Abstract
Cylindromatosis (CYLD) is a deubiquitinase that was initially identified as a tumor suppressor and has recently been implicated in diverse normal physiologic processes. In this study, we have investigated the involvement of CYLD in angiogenesis, the formation of new blood vessels from preexisting ones. We find that knockdown of CYLD expression significantly impairs angiogenesis in vitro in both matrigel-based tube formation assay and collagen-based 3-dimensional capillary sprouting assay. Disruption of CYLD also remarkably inhibits angiogenic response in vivo, as evidenced by diminished blood vessel growth into the angioreactors implanted in mice. Mechanistic studies show that CYLD regulates angiogenesis by mediating the spreading and migration of vascular endothelial cells. Silencing of CYLD dramatically decreases microtubule dynamics in endothelial cells and inhibits endothelial cell migration by blocking the polarization process. Furthermore, we identify Rac1 activation as an important factor contributing to the action of CYLD in regulating endothelial cell migration and angiogenesis. Our findings thus uncover a previously unrecognized role for CYLD in the angiogenic process and provide a novel mechanism for Rac1 activation during endothelial cell migration and angiogenesis.
- Published
- 2010
22. Tumour suppressor CYLD is a negative regulator of the mitotic kinase Aurora-B
- Author
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Jun Zhou, Lihong Huo, Xiaoou Sun, Jinmin Gao, Chuanmao Zhang, Xingjuan Shi, Dengwen Li, Lei Sun, and Min Liu
- Subjects
biology ,Tumor suppressor gene ,Aurora B kinase ,macromolecular substances ,Protein phosphatase 2 ,Molecular biology ,Pathology and Forensic Medicine ,Deubiquitinating enzyme ,Deubiquitinating Enzyme CYLD ,Cell biology ,enzymes and coenzymes (carbohydrates) ,embryonic structures ,biology.protein ,Phosphorylation ,Aurora Kinase B ,biological phenomena, cell phenomena, and immunity ,Kinase activity - Abstract
The familial cylindromatosis tumour suppressor CYLD contains three cytoskeleton-associated protein glycine-rich (CAP-Gly) domains and a deubiquitinase domain. The tumour-suppressing function of CYLD has been attributed to its deubiquitinase domain, which removes lysine-63-linked polyubiquitin chains from target proteins, leading to the inhibition of cell survival and proliferation. In this study, we have detected an interaction of CYLD with the mitotic kinase Aurora-B. The interaction is mediated by the third CAP-Gly domain of CYLD and results in suppression of Aurora-B activity. Mechanistic studies reveal that the inhibition of Aurora-B activity by CYLD is independent of its deubiquitinase activity. Instead, CYLD interacts with protein phosphatase 2A (PP2A) and promotes the ability of PP2A to bind and dephosphorylate Aurora-B at threonine-232. Cylindromatosis-associated truncating mutations of CYLD abolish its interaction with PP2A, its enhancing effect on the PP2A/Aurora-B interaction, and its inhibitory effect on Aurora-B activity. These findings uncover Aurora-B and PP2A as novel binding partners of CYLD and suggest that CYLD negatively regulates Aurora-B activity through acting on the PP2A axis.
- Published
- 2010
23. Leptin-Dependent Control of Glucose Balance and Locomotor Activity by POMC Neurons
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Christian Bjørbæk, Xing-Hong Leng, José P. Silva, Sarah Greeley, Kevin M. Gamber, Nicholas Huntoon, and Lihong Huo
- Subjects
Blood Glucose ,Leptin ,medicine.medical_specialty ,Pro-Opiomelanocortin ,Physiology ,HUMDISEASE ,030209 endocrinology & metabolism ,Motor Activity ,Biology ,MOLNEURO ,Article ,Eating ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Diabetes mellitus ,Internal medicine ,medicine ,Animals ,Glucose homeostasis ,Molecular Biology ,030304 developmental biology ,Balance (ability) ,Mice, Knockout ,Neurons ,2. Zero hunger ,0303 health sciences ,Leptin receptor ,Body Weight ,digestive, oral, and skin physiology ,Cell Biology ,medicine.disease ,Obesity ,Peripheral ,Endocrinology ,nervous system ,Receptors, Leptin ,Signal transduction ,hormones, hormone substitutes, and hormone antagonists ,Signal Transduction - Abstract
SummaryLeptin plays a pivotal role in regulation of energy balance. Via unknown central pathways, leptin also affects peripheral glucose homeostasis and locomotor activity. We hypothesized that, specifically, pro-opiomelanocortin (POMC) neurons mediate those actions. To examine this possibility, we applied Cre-Lox technology to express leptin receptors (ObRb) exclusively in POMC neurons of the morbidly obese, profoundly diabetic, and severely hypoactive leptin receptor-deficient Leprdb/db mice. Here, we show that expression of ObRb only in POMC neurons leads to a marked decrease in energy intake and a modest reduction in body weight in Leprdb/db mice. Remarkably, blood glucose levels are entirely normalized. This normalization occurs independently of changes in food intake and body weight. In addition, physical activity is greatly increased despite profound obesity. Our results suggest that leptin signaling exclusively in POMC neurons is sufficient to stimulate locomotion and prevent diabetes in the severely hypoactive and hyperglycemic obese Leprdb/db mice.
- Published
- 2009
24. Divergent Regulation of Proopiomelanocortin Neurons by Leptin in the Nucleus of the Solitary Tract and in the Arcuate Hypothalamic Nucleus
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Lihong Huo, Christian Bjørbæk, and Harvey J. Grill
- Subjects
Leptin ,Male ,STAT3 Transcription Factor ,endocrine system ,medicine.medical_specialty ,Pro-Opiomelanocortin ,Endocrinology, Diabetes and Metabolism ,Population ,Adipokine ,Mice ,Proopiomelanocortin ,Internal medicine ,Solitary Nucleus ,Internal Medicine ,medicine ,Animals ,Phosphorylation ,education ,Neurons ,education.field_of_study ,biology ,digestive, oral, and skin physiology ,Arcuate Nucleus of Hypothalamus ,Solitary tract ,respiratory system ,Immunohistochemistry ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Endocrinology ,nervous system ,Hypothalamus ,biology.protein ,Neuron ,Proto-Oncogene Proteins c-fos ,Nucleus ,hormones, hormone substitutes, and hormone antagonists - Abstract
Proopiomelanocortin (POMC) neurons in the arcuate nucleus (ARC) of the hypothalamus are activated by leptin and mediate part of leptin’s central actions to influence energy balance. However, little is known about potential leptin signaling in POMC neurons located in the nucleus of the solitary tract (NTS), the only other known population of POMC neurons. Leptin-responsive neurons do exist in the NTS, but their neurochemical phenotype is largely unknown. The contribution of NTS POMC neurons versus ARC POMC neurons in leptin action is thus undetermined. We show here that in contrast to POMC neurons in the ARC, leptin does not stimulate phosphorylation of signal-transducer and activator of transcription 3 in NTS POMC neurons of POMC-EGFP reporter mice. In addition, leptin does not induce c-Fos expression in NTS POMC neurons unlike ARC POMC neurons. Fasting induces a fall in POMC mRNA in both the ARC and the NTS, but different from the ARC, the reduction in NTS POMC mRNA is not reversed by leptin. We conclude that POMC neurons in the NTS do not respond to leptin unlike ARC POMC neurons. POMC neurons in the hypothalamus may therefore mediate all of leptin’s signaling via POMC-derived peptides in the central nervous system.
- Published
- 2006
25. HPRTMutants Induced in Bystander Cells by Very Low Fluences of Alpha Particles Result Primarily from Point Mutations
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Hatsumi Nagasawa, Lihong Huo, and John B. Little
- Subjects
Genetics ,Hypoxanthine Phosphoribosyltransferase ,Mutation ,Radiation ,Chinese hamster ovary cell ,Point mutation ,Mutant ,Biophysics ,Hamster ,Bystander Effect ,CHO Cells ,Biology ,Alpha Particles ,medicine.disease_cause ,Molecular biology ,Hypoxanthine-guanine phosphoribosyltransferase ,Cell culture ,Cricetinae ,Bystander effect ,medicine ,Animals ,Point Mutation ,Radiology, Nuclear Medicine and imaging ,Reactive Oxygen Species - Abstract
We have shown previously that damage signals may be transmitted from irradiated cells to nonirradiated cells in monolayer cultures, leading to changes in gene expression and an enhanced frequency of mutations in these "bystander" cells. The present study was designed to test the hypothesis that mutations occurring in bystander cells result from a different mechanism than those occurring in irradiated cells, and thus show differences in molecular structure. Structural changes in the HPRT gene of Chinese hamster ovary (CHO) cells were determined by multiplex PCR analysis. A total of 790 mutant clones derived from monolayer cultures exposed to mean doses of 0, 0.5 or 10 cGy of alpha-particle radiation (0, 3% or 44%, respectively, of nuclei traversed by one or more alpha particles) were examined. Whereas mutations induced by 10 cGy included a high frequency of deletions, nearly all mutations occurring in bystander cells in cultures irradiated with 0.5 cGy involved point mutations, confirming our hypothesis that they are induced by a different mechanism.
- Published
- 2001
26. Modulation of Eg5 activity contributes to mitotic spindle checkpoint activation and Tat-mediated apoptosis in CD4-positive T-lymphocytes
- Author
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Min, Liu, Dengwen, Li, Lei, Sun, Jie, Chen, Xiaodong, Sun, Linlin, Zhang, Lihong, Huo, and Jun, Zhou
- Subjects
CD4-Positive T-Lymphocytes ,Hydrolysis ,Lysine ,Kinesins ,Mitosis ,Apoptosis ,Spindle Apparatus ,Transfection ,Adenosine Diphosphate ,Jurkat Cells ,Adenosine Triphosphate ,Allosteric Regulation ,HIV-1 ,Humans ,M Phase Cell Cycle Checkpoints ,Protein Interaction Domains and Motifs ,tat Gene Products, Human Immunodeficiency Virus ,Protein Binding ,Signal Transduction - Abstract
Tat, the transactivation factor of human immunodeficiency virus type 1 (HIV-1), represents one of the major players mediating the loss of CD4-positive T-lymphocytes in HIV-1-infected patients, primarily due to the ability of Tat to trigger apoptosis. However, the molecular events underlying this process remain elusive. In this study, we provide evidence that Tat interacts with Eg5, a microtubule-associated motor protein, and allosterically modulates the ATPase activity of Eg5 by affecting ADP release from the enzyme's active centre. This action of Tat impairs the formation of the mitotic spindle and activates the spindle checkpoint, thereby blocking cell cycle progression at mitosis and leading to apoptosis. Further studies reveal that lysine 85 in the carboxyl terminus of Tat is critical for its interaction with Eg5 and hence its effects on Eg5 activity, mitotic progression, and apoptosis. These findings identify Tat as a viral regulator of Eg5 and provide novel insights into the mechanisms of action of Tat in mediating the reduction of CD4-positive T-lymphocytes.
- Published
- 2013
27. Somato-Dendritic Localization and Signaling by Leptin Receptors in Hypothalamic POMC and AgRP Neurons
- Author
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Thompson Zhang, Shane T. Hentges, Elizabeth J. Benecchi, Joyce E. Hairston, Maria Ericsson, Christian Bjørbæk, Lihong Huo, Scott Baver, Nicholas Huntoon, Sangdeuk Ha, Adriana Gata, and Wenjing Li
- Subjects
Male ,STAT3 Transcription Factor ,medicine.medical_specialty ,Pro-Opiomelanocortin ,Hypothalamus ,Neuropeptide ,lcsh:Medicine ,Biology ,Rats, Sprague-Dawley ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Arcuate nucleus ,Orexigenic ,Internal medicine ,medicine ,Animals ,Agouti-Related Protein ,Phosphorylation ,lcsh:Science ,030304 developmental biology ,Neurons ,0303 health sciences ,Multidisciplinary ,Leptin receptor ,Leptin ,lcsh:R ,digestive, oral, and skin physiology ,Cell Membrane ,Dendrites ,Neuropeptide Y receptor ,Axons ,Cell biology ,Rats ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Endocrinology ,nervous system ,Synapses ,Receptors, Leptin ,lcsh:Q ,Neuron ,030217 neurology & neurosurgery ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug ,Research Article ,Signal Transduction - Abstract
Leptin acts via neuronal leptin receptors to control energy balance. Hypothalamic pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP)/Neuropeptide Y (NPY)/GABA neurons produce anorexigenic and orexigenic neuropeptides and neurotransmitters, and express the long signaling form of the leptin receptor (LepRb). Despite progress in the understanding of LepRb signaling and function, the sub-cellular localization of LepRb in target neurons has not been determined, primarily due to lack of sensitive anti-LepRb antibodies. Here we applied light microscopy (LM), confocal-laser scanning microscopy (CLSM), and electron microscopy (EM) to investigate LepRb localization and signaling in mice expressing a HA-tagged LepRb selectively in POMC or AgRP/NPY/GABA neurons. We report that LepRb receptors exhibit a somato-dendritic expression pattern. We further show that LepRb activates STAT3 phosphorylation in neuronal fibers within several hypothalamic and hindbrain nuclei of wild-type mice and rats, and specifically in dendrites of arcuate POMC and AgRP/NPY/GABA neurons of Leprb (+/+) mice and in Leprb (db/db) mice expressing HA-LepRb in a neuron specific manner. We did not find evidence of LepRb localization or STAT3-signaling in axon-fibers or nerve-terminals of POMC and AgRP/NPY/GABA neurons. Three-dimensional serial EM-reconstruction of dendritic segments from POMC and AgRP/NPY/GABA neurons indicates a high density of shaft synapses. In addition, we found that the leptin activates STAT3 signaling in proximity to synapses on POMC and AgRP/NPY/GABA dendritic shafts. Taken together, these data suggest that the signaling-form of the leptin receptor exhibits a somato-dendritic expression pattern in POMC and AgRP/NPY/GABA neurons. Dendritic LepRb signaling may therefore play an important role in leptin's central effects on energy balance, possibly through modulation of synaptic activity via post-synaptic mechanisms.
- Published
- 2013
28. Systematic Analysis of the Functions of Lysine Acetylation in the Regulation of Tat Activity
- Author
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Huabin Liang, Chengye Feng, Zhangyong Hong, Minghao He, Lihong Huo, Linlin Zhang, Xutian Jing, Danyao Du, Xincheng Wang, Jun Zhou, Lei Sun, and Min Liu
- Subjects
Glutamine ,Lysine ,lcsh:Medicine ,Mitosis ,Apoptosis ,Plasma protein binding ,Arginine ,complex mixtures ,Microtubules ,Biochemistry ,Protein Chemistry ,Transactivation ,Jurkat Cells ,Microtubule ,Humans ,lcsh:Science ,Biology ,Multidisciplinary ,Alanine ,biology ,lcsh:R ,Proteins ,Acetylation ,Subcellular localization ,Bromodomain ,Tubulin ,HEK293 Cells ,Mutation ,biology.protein ,HIV-1 ,bacteria ,lcsh:Q ,tat Gene Products, Human Immunodeficiency Virus ,Protein Binding ,Research Article - Abstract
The Tat protein of HIV-1 has several well-known properties, such as nucleocytoplasmic trafficking, transactivation of transcription, interaction with tubulin, regulation of mitotic progression, and induction of apoptosis. Previous studies have identified a couple of lysine residues in Tat that are essential for its functions. In order to analyze the functions of all the lysine residues in Tat, we mutated them individually to alanine, glutamine, and arginine. Through systematic analysis of the lysine mutants, we discovered several previously unidentified characteristics of Tat. We found that lysine acetylation could modulate the subcellular localization of Tat, in addition to the regulation of its transactivation activity. Our data also revealed that lysine mutations had distinct effects on microtubule assembly and Tat binding to bromodomain proteins. By correlation analysis, we further found that the effects of Tat on apoptosis and mitotic progression were not entirely attributed to its effect on microtubule assembly. Our findings suggest that Tat may regulate diverse cellular activities through binding to different proteins and that the acetylation of distinct lysine residues in Tat may modulate its interaction with various partners.
- Published
- 2013
29. miR-219a-5p inhibits breast cancer cell migration and epithelial-mesenchymal transition by targeting myocardin-related transcription factor A.
- Author
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Chunyu Zhuang, Ying Yuan, Tiefeng Song, Huiqin Wang, Liwen Huang, Xuegang Luo, Hongpeng He, Lihong Huo, Hao Zhou, Nan Wang, and Tongcun Zhang
- Published
- 2017
- Full Text
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30. Over-Expression of Leptin Receptors in Hypothalamic POMC Neurons Increases Susceptibility to Diet-Induced Obesity
- Author
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Lihong Huo, Sarah Greeley, Christian Bjørbæk, Joyce E. Hairston, Kevin M. Gamber, and Sangdeuk Ha
- Subjects
Male ,Pro-Opiomelanocortin ,lcsh:Medicine ,Suppressor of Cytokine Signaling Proteins ,Mice ,0302 clinical medicine ,Endocrinology ,Molecular Cell Biology ,SOCS3 ,Phosphorylation ,STAT3 ,Receptor ,lcsh:Science ,Diet, Fat-Restricted ,In Situ Hybridization ,Neurons ,0303 health sciences ,Multidisciplinary ,Leptin ,digestive, oral, and skin physiology ,Animal Models ,Immunohistochemistry ,Hypothalamus ,Body Composition ,Medicine ,Receptors, Leptin ,Signal transduction ,hormones, hormone substitutes, and hormone antagonists ,Research Article ,Signal Transduction ,STAT3 Transcription Factor ,medicine.medical_specialty ,endocrine system ,In situ hybridization ,Biology ,Diet, High-Fat ,Signaling Pathways ,03 medical and health sciences ,Model Organisms ,Internal medicine ,medicine ,Genetics ,Animals ,Obesity ,030304 developmental biology ,Nutrition ,Leptin receptor ,Endocrine Physiology ,lcsh:R ,nutritional and metabolic diseases ,Mice, Inbred C57BL ,nervous system ,Suppressor of Cytokine Signaling 3 Protein ,biology.protein ,lcsh:Q ,030217 neurology & neurosurgery - Abstract
Diet-induced obesity (DIO) in rodents is characterized by impaired activation of signal-transducer and activator of transcription 3 (STAT3) by leptin receptors (LepRb) within the hypothalamic arcuate nucleus. This signaling defect likely plays an important role in development of DIO. However, the neuro-chemical identity of the leptin-STAT3 resistant arcuate neurons has not been determined and the underlying mechanisms responsible for development of cellular leptin resistance remain unclear. To investigate this, we first measured arcuate gene expression of known key signaling components of the LepRb signaling pathway and tested whether specifically the critical arcuate pro-opiomelanocortin (POMC) neurons are resistant to LepRb-STAT3 signaling in mice given a high-fat-diet (HFD) compared to mice provided a low-fat control diet (LFD). We found that leptin-dependent STAT3 phosphorylation was decreased within POMC neurons of HFD mice. In addition, Leprb mRNA and suppressor of cytokine signaling 3 (Socs3) mRNA were elevated in the arcuate of HFD mice. To investigate whether increased LepRb expression per se in POMC neurons can influence development of DIO and Socs3 expression, we created mice that over-express LepRb selectively in POMC neurons (POMC-LepRb). No differences in body weight, fat mass or food intake were found between LFD POMC-LepRb mice and LFD controls. Surprisingly, body weight, fat mass and caloric intake of HFD POMC-LepRb mice was markedly higher than HFD control mice. In addition, arcuate Socs3 mRNA was increased in HFD POMC-LepRb mice compared to HFD controls. These data show that specifically POMC neurons of DIO mice are resistant to STAT3 activation by leptin, indicating that those cells might play a role in development of DIO. Furthermore, over-expression of LepRb selectively in POMC neurons increases susceptibility to the development of DIO. We propose a model where over-reactivity of the leptin-LepRb signaling system in arcuate neurons may play causal a role in development of diet-induced obesity.
- Published
- 2012
31. Microtubule-associated deacetylase HDAC6 promotes angiogenesis by regulating cell migration in an EB1-dependent manner
- Author
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Songbo Xie, Jinmin Gao, Jun Zhou, Yuan Ren, Lihong Huo, Min Liu, Dengwen Li, and Dandan Cui
- Subjects
Membrane ruffling ,Angiogenesis ,Neovascularization, Physiologic ,Chick Embryo ,Biology ,Histone Deacetylase 6 ,Hydroxamic Acids ,Biochemistry ,Histone Deacetylases ,Neovascularization ,Mice ,Cell Movement ,Drug Discovery ,medicine ,Animals ,Humans ,Anilides ,Microtubule end ,Cells, Cultured ,Tube formation ,Cell Polarity ,Endothelial Cells ,Cell migration ,Cell Biology ,HDAC6 ,Cell biology ,Endothelial stem cell ,medicine.symptom ,Chickens ,Microtubule-Associated Proteins ,Biotechnology ,Research Article - Abstract
Angiogenesis, a process by which the preexisting blood vasculature gives rise to new capillary vessels, is associated with a variety of physiologic and pathologic conditions. However, the molecular mechanism underlying this important process remains poorly understood. Here we show that histone deacetylase 6 (HDAC6), a microtubule-associated enzyme critical for cell motility, contributes to angiogenesis by regulating the polarization and migration of vascular endothelial cells. Inhibition of HDAC6 activity impairs the formation of new blood vessels in chick embryos and in angioreactors implanted in mice. The requirement for HDAC6 in angiogenesis is corroborated in vitro by analysis of endothelial tube formation and capillary sprouting. Our data further show that HDAC6 stimulates membrane ruffling at the leading edge to promote cell polarization. In addition, microtubule end binding protein 1 (EB1) is important for HDAC6 to exert its activity towards the migration of endothelial cells and generation of capillary-like structures. These results thus identify HDAC6 as a novel player in the angiogenic process and offer novel insights into the molecular mechanism governing endothelial cell migration and angiogenesis.
- Published
- 2011
32. Regulation of Tat Acetylation and Transactivation Activity by the Microtubule-associated Deacetylase HDAC6*
- Author
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Jun Zhou, Xingjuan Shi, Lihong Huo, Wei Yang, Xiaoou Sun, Dengwen Li, Wentao Qiao, Prasanthi Karna, Min Liu, and Ritu Aneja
- Subjects
Gene Expression Regulation, Viral ,Transcriptional Activation ,Cyclin T1 ,Transcription, Genetic ,Biology ,Histone Deacetylase 6 ,Biochemistry ,Jurkat cells ,Microtubules ,Histone Deacetylases ,Transactivation ,Jurkat Cells ,Mice ,Transcription (biology) ,Animals ,Humans ,Promoter Regions, Genetic ,Molecular Biology ,Regulation of gene expression ,Mice, Knockout ,Cyclin T ,Acetylation ,Cell Biology ,HDAC6 ,Molecular biology ,HEK293 Cells ,HIV-1 ,tat Gene Products, Human Immunodeficiency Virus ,Histone deacetylase ,Signal Transduction - Abstract
Reversible acetylation of Tat is critical for its transactivation activity toward HIV-1 transcription. However, the enzymes involved in the acetylation/deacetylation cycles have not been fully characterized. In this study, by yeast two-hybrid assay, we have discovered the histone deacetylase HDAC6 to be a binding partner of Tat. Our data show that HDAC6 interacts with Tat in the cytoplasm in a microtubule-dependent manner. In addition, HDAC6 deacetylates Tat at Lys-28 and thereby suppresses Tat-mediated transactivation of the HIV-1 promoter. Inactivation of HDAC6 promotes the interaction of Tat with cyclin T1 and leads to an increase in Tat transactivation activity. These findings establish HDAC6 as a Tat deacetylase and support a model in which Lys-28 deacetylation decreases Tat transactivation activity through affecting the ability of Tat to form a ribonucleoprotein complex with cyclin T1 and the transactivation-responsive RNA.
- Published
- 2011
33. Tumour suppressor CYLD is a negative regulator of the mitotic kinase Aurora-B
- Author
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Lei, Sun, Jinmin, Gao, Lihong, Huo, Xiaoou, Sun, Xingjuan, Shi, Min, Liu, Dengwen, Li, Chuanmao, Zhang, and Jun, Zhou
- Subjects
Microscopy, Fluorescence ,Aurora Kinases ,Gene Knockdown Techniques ,Tumor Suppressor Proteins ,Aurora Kinase B ,Humans ,Protein Phosphatase 2 ,Phosphorylation ,Protein Serine-Threonine Kinases ,Cells, Cultured ,Deubiquitinating Enzyme CYLD ,HeLa Cells - Abstract
The familial cylindromatosis tumour suppressor CYLD contains three cytoskeleton-associated protein glycine-rich (CAP-Gly) domains and a deubiquitinase domain. The tumour-suppressing function of CYLD has been attributed to its deubiquitinase domain, which removes lysine-63-linked polyubiquitin chains from target proteins, leading to the inhibition of cell survival and proliferation. In this study, we have detected an interaction of CYLD with the mitotic kinase Aurora-B. The interaction is mediated by the third CAP-Gly domain of CYLD and results in suppression of Aurora-B activity. Mechanistic studies reveal that the inhibition of Aurora-B activity by CYLD is independent of its deubiquitinase activity. Instead, CYLD interacts with protein phosphatase 2A (PP2A) and promotes the ability of PP2A to bind and dephosphorylate Aurora-B at threonine-232. Cylindromatosis-associated truncating mutations of CYLD abolish its interaction with PP2A, its enhancing effect on the PP2A/Aurora-B interaction, and its inhibitory effect on Aurora-B activity. These findings uncover Aurora-B and PP2A as novel binding partners of CYLD and suggest that CYLD negatively regulates Aurora-B activity through acting on the PP2A axis.
- Published
- 2010
34. Tat acetylation regulates its actions on microtubule dynamics and apoptosis in T lymphocytes
- Author
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Xin Dong, Xiaoou Sun, Xingjuan Shi, Jun Zhou, Jingyu Li, Dengwen Li, Lei Sun, Min Liu, Bin Dong, and Lihong Huo
- Subjects
Programmed cell death ,T-Lymphocytes ,Apoptosis ,Biology ,Transfection ,Jurkat cells ,Microtubules ,Translocation, Genetic ,Pathology and Forensic Medicine ,Transactivation ,Jurkat Cells ,Microtubule ,Proto-Oncogene Proteins ,Humans ,Bcl-2-Like Protein 11 ,Lysine ,Membrane Proteins ,Acetylation ,T lymphocyte ,Cell biology ,Tubulin ,biology.protein ,HIV-1 ,tat Gene Products, Human Immunodeficiency Virus ,Apoptosis Regulatory Proteins ,HeLa Cells - Abstract
The transactivator protein Tat of human immunodeficiency virus type 1 (HIV-1) is known to suppress microtubule dynamics and thereby trigger apoptosis in T lymphocytes. These actions of Tat constitute one of the major mechanisms for the massive destruction of T lymphocytes associated with the acquired immunodeficiency syndrome. Herein, we show that Tat acetylation at lysine-28 (K28) enhances its interaction with microtubules and increases its activity to promote microtubule assembly, by lowering the critical concentration of tubulin for polymerization into microtubules. In addition, K28 acetylation enhances the ability of Tat to stabilize microtubules, leading to increased apoptosis in T lymphocytes. Our data further reveal that Tat acetylation at K28 stimulates its activity to induce the translocation of Bim, a pro-apoptotic protein of the Bcl-2 family, from microtubules to mitochondria. These findings provide the first evidence that Tat acetylation regulates its actions on microtubule dynamics and apoptosis, in addition to the regulation of its transactivation activity.
- Published
- 2010
35. Validating the mitotic kinesin Eg5 as a therapeutic target in pancreatic cancer cells and tumor xenografts using a specific inhibitor
- Author
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Minggang Li, Min Liu, Lihong Huo, Jun Zhou, Jianchao Liu, and Haiyang Yu
- Subjects
Pathology ,medicine.medical_specialty ,Pancreatic disease ,medicine.medical_treatment ,Kinesins ,Mice, Nude ,Antineoplastic Agents ,Apoptosis ,Biochemistry ,Targeted therapy ,Mice ,Pancreatic cancer ,Cell Line, Tumor ,medicine ,Animals ,Humans ,Mitosis ,Cell Proliferation ,Pharmacology ,business.industry ,Caspase 3 ,Cancer ,Thiones ,medicine.disease ,Xenograft Model Antitumor Assays ,Transplantation ,Pancreatic Neoplasms ,Spindle checkpoint ,Cancer research ,Quinazolines ,Female ,business ,Multipolar spindles - Abstract
Pancreatic cancer is a devastating disease with a high mortality rate. Treatment of this malignancy remains a big challenge in oncology, and none of the currently available chemotherapeutic agents has a remarkable impact on improving patient survival. Consequently, it is important to explore new targets and find effective drugs for the management of this disease. Here we report that inhibition of the mitotic kinesin Eg5 by a pharmacological compound effectively prevents the proliferation of pancreatic cancer cells by halting mitotic progression, resulting in robust apoptosis. The mitotic arrest induced by this agent is attributed to its interference with spindle formation and activation of the spindle checkpoint. Impairment of the spindle checkpoint significantly compromises both mitotic arrest and apoptosis induced by the Eg5 inhibitor, suggesting the importance of the spindle checkpoint in monitoring Eg5 inhibitor sensitivity. Furthermore, treatment of nude mice bearing tumor xenografts of human pancreatic cancer results in pronounced tumor regression by triggering apoptosis. These data thus indicate Eg5 as a potential target for pancreatic cancer treatment.
- Published
- 2008
36. The tumor suppressor CYLD regulates microtubule dynamics and plays a role in cell migration
- Author
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Min Liu, Jinmin Gao, Xiaoou Sun, Jun Zhou, Lihong Huo, Jin-Tang Dong, and Dengwen Li
- Subjects
Biology ,Biochemistry ,Microtubules ,Deubiquitinating Enzyme CYLD ,law.invention ,chemistry.chemical_compound ,Protein structure ,Microtubule ,law ,Cell Movement ,Tubulin ,Humans ,Molecular Biology ,Gene knockdown ,Wound Healing ,integumentary system ,Tubulin Modulators ,Nocodazole ,Tumor Suppressor Proteins ,Cell migration ,Cell Biology ,Cell biology ,Protein Structure, Tertiary ,chemistry ,Gene Expression Regulation ,Suppressor ,HeLa Cells - Abstract
The familial cylindromatosis tumor suppressor CYLD is known to contain three cytoskeleton-associated protein glycine-rich (CAP-Gly) domains, which exist in a number of microtubule-binding proteins and are responsible for their association with microtubules. However, it remains elusive whether CYLD interacts with microtubules and, if so, whether the interaction is mediated by the CAP-Gly domains. In this study, our data demonstrate that CYLD associates with microtubules both in cells and in vitro, and the first CAP-Gly domain of CYLD is mainly responsible for the interaction. Knockdown of cellular CYLD expression dramatically delays microtubule regrowth after nocodazole washout, indicating an activity for CYLD in promoting microtubule assembly. Our data further demonstrate that CYLD enhances tubulin polymerization into microtubules by lowering the critical concentration for microtubule assembly. In addition, we have identified by wound healing assay a critical role for CYLD in mediating cell migration and found that its first CAP-Gly domain is required for this activity. Thus CYLD joins a growing list of CAP-Gly domain-containing proteins that regulate microtubule dynamics and function.
- Published
- 2008
37. Divergent Leptin Signaling in Proglucagon Neurons of the Nucleus of the Solitary Tract in Mice and Rats
- Author
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Lihong Huo, Kevin M. Gamber, Harvey J. Grill, and Christian Bjørbæk
- Subjects
Leptin ,Male ,STAT3 Transcription Factor ,medicine.medical_specialty ,Adipokine ,Gene Expression ,Biology ,Proglucagon ,Article ,Rats, Sprague-Dawley ,Mice ,Endocrinology ,Species Specificity ,Glucagon-Like Peptide 1 ,Internal medicine ,medicine ,Solitary Nucleus ,Animals ,RNA, Messenger ,Phosphorylation ,Neurons ,Solitary nucleus ,digestive, oral, and skin physiology ,Solitary tract ,Glucagon-like peptide-1 ,Rats ,Mice, Inbred C57BL ,medicine.anatomical_structure ,nervous system ,Hypothalamus ,Neuron ,hormones, hormone substitutes, and hormone antagonists ,Signal Transduction - Abstract
The central targets mediating the anorectic and other actions of leptin have yet to be fully identified. Although previous studies focused on the hypothalamus, leptin also acts on neurons in extrahypothalamic sites, including the nucleus of the solitary tract (NTS). Moreover, injection of leptin into the NTS of rats suppresses food intake. Within the central nervous system, glucagon-like peptide (GLP-1), a product of proglucagon, is synthesized almost exclusively in neurons of the NTS. Intracerebroventricular administration of GLP-1 inhibits energy intake, and GLP-1 receptor antagonists attenuate the anorexic effects of leptin in rats. To examine whether NTS proglucagon neurons are directly regulated by leptin, we performed double GLP-1 and phosphorylation of signal transducer and activator of transcription-3 immunohistochemistry on brain sections from ip leptin-treated mice and rats. Leptin induced phosphorylation of signal transducer and activator of transcription-3 in 100% of GLP-1 cells in the caudal brainstem of mice. In striking contrast, 0% of GLP-1-positive neurons in rats responded to leptin. We then measured regulation of NTS proglucagon mRNA using real-time RT-PCR in mice and rats fed ad libitum, fasted, or fasted and treated ip with leptin. In mice, proglucagon mRNA fell by fasting, and this was prevented by leptin administration. In rats, by contrast, proglucagon mRNA was unaffected by either fasting or leptin. Taken together, our studies reveal direct regulation of proglucagon neurons by leptin in mice but not rats along with corresponding species differences in the regulation of proglucagon mRNA expression. These data, combined with previous results, suggest a different mechanism of interaction between leptin and NTS proglucagon neurons in mice and rats.
- Published
- 2007
38. Leptin and the control of food intake: neurons in the nucleus of the solitary tract are activated by both gastric distension and leptin
- Author
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Harvey J. Grill, Christian Bjørbæk, Lisa Y. Maeng, and Lihong Huo
- Subjects
Leptin ,Male ,medicine.medical_specialty ,Adipokine ,Biology ,Distension ,Catheterization ,Rats, Sprague-Dawley ,Eating ,Mice ,Endocrinology ,Internal medicine ,medicine ,Solitary Nucleus ,Animals ,Phosphorylation ,Neurons ,Solitary nucleus ,Gastric distension ,digestive, oral, and skin physiology ,Area postrema ,Stomach ,Recombinant Proteins ,Rats ,medicine.anatomical_structure ,nervous system ,Forebrain ,Neuron ,medicine.symptom ,hormones, hormone substitutes, and hormone antagonists ,Signal Transduction - Abstract
Leptin reduces food intake by an unspecified mechanism. Studies show that forebrain ventricular leptin delivery increases the inhibitory effects of gastrointestinal (GI) stimulation on intake and amplifies the electrophysiological response to gastric distension in neurons of the medial subnucleus of the nucleus tractus solitarius (mNTS). However, forebrain ventricular delivery leaves unspecified the neuroanatomical site(s) mediating leptin’s effect on intake. Detailed anatomical analysis in rats and mice by phosphorylated signal transducer and activator of transcription 3 immunohistochemistry shows that hindbrain leptin-responsive neurons are located exclusively within the mNTS. Here, we investigate 1) whether leptin and gastric distension affect the same mNTS neurons and 2) whether the intake-inhibitory action of gastric distension is potentiated by hindbrain leptin delivery. Twenty-five minutes after gastric balloon distension or sham distension, rats were injected with leptin or vehicle and killed 35 min later. Double-fluorescent immunohistochemistry for phosphorylated signal transducer and activator of transcription 3 and c-Fos revealed that about 40% of leptin-responsive cells also respond to gastric distension. A paradigm was then developed to examine the relationship between leptin and gastric distension volume on intake inhibition. At subthreshold levels, hindbrain ventricular leptin or distension volume were without effect. When combined, an interaction occurred that significantly reduced food intake. We conclude that 1) leptin-responsive neurons in the hindbrain are primarily located in the mNTS at the level of the area postrema, a key vagal afferent projection zone of the GI system; 2) a significant proportion of leptin-responsive neurons in the mNTS are activated by stomach distension; and 3) leptin delivered to the hindbrain is sufficient to potentiate the intake-suppressive effects of an otherwise ineffective volume of gastric distension. These results are consistent with the hypothesis that leptin acts directly on neurons within the mNTS to reduce food intake through an interaction with GI signal processing.
- Published
- 2007
39. Regulation of hypothalamic prohormone convertases 1 and 2 and effects on processing of prothyrotropin-releasing hormone
- Author
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Eduardo A. Nillni, Lihong Huo, Heike Münzberg, Christian Bjørbæk, Jorge Goldstein, Virginia Hovanesian, Theodore C. Friedman, Ronald C. Stuart, and Vanesa C. Sanchez
- Subjects
Leptin ,Male ,medicine.medical_specialty ,endocrine system ,Prohormone ,Hypothalamus ,Proprotein convertase 2 ,Thyrotropin-releasing hormone ,Neuropeptide ,Proprotein convertase 1 ,Biology ,Article ,Gene Expression Regulation, Enzymologic ,Rats, Sprague-Dawley ,Mice ,Pregnancy ,Internal medicine ,medicine ,Animals ,RNA, Messenger ,Thyrotropin-Releasing Hormone ,Cells, Cultured ,Neurons ,digestive, oral, and skin physiology ,General Medicine ,Immunohistochemistry ,Recombinant Proteins ,Rats ,Thyroxine ,Endocrinology ,Proprotein Convertase 2 ,Proprotein Convertase 1 ,Median eminence ,Triiodothyronine ,Female ,Energy Intake ,Protein Processing, Post-Translational ,hormones, hormone substitutes, and hormone antagonists ,Injections, Intraperitoneal ,medicine.drug - Abstract
Regulation of energy balance by leptin involves regulation of several neuropeptides, including thyrotropin-releasing hormone (TRH). Synthesized from a larger inactive precursor, its maturation requires proteolytic cleavage by prohormone convertases 1 and 2 (PC1 and PC2). Since this maturation in response to leptin requires prohormone processing, we hypothesized that leptin might regulate hypothalamic PC1 and PC2 expression, ultimately leading to coordinated processing of prohormones into mature peptides. Using hypothalamic neurons, we found that leptin stimulated PC1 and PC2 mRNA and protein expression and also increased PC1 and PC2 promoter activities in transfected 293T cells. Starvation of rats, leading to low serum leptin levels, decreased PC1 and PC2 gene and protein expression in the paraventricular nucleus (PVN) of the hypothalamus. Exogenous administration of leptin to fasted animals restored PC1 levels in the median eminence (ME) and the PVN to approximately the level found in fed control animals. Consistent with this regulation of PCs in the PVN, concentrations of TRH in the PVN and ME were substantially reduced in the fasted animals relative to the fed animals, and leptin reversed this decrease. Further analysis showed that proteolytic cleavage of pro-thyrotropin-releasing hormone (proTRH) at known PC cleavage sites was reduced by fasting and increased in animals given leptin. Combined, these findings suggest that leptin-dependent stimulation of hypothalamic TRH expression involves both activation of trh transcription and stimulation of PC1 and PC2 expression, which lead to enhanced processing of proTRH into mature TRH.
- Published
- 2004
40. Role of signal transducer and activator of transcription 3 in regulation of hypothalamic trh gene expression by leptin
- Author
-
Lihong Huo, Eduardo A. Nillni, Heike Münzberg, and Christian Bjørbæk
- Subjects
Leptin ,Male ,STAT3 Transcription Factor ,endocrine system ,medicine.medical_specialty ,endocrine system diseases ,Thyrotropin-releasing hormone ,Receptors, Cell Surface ,Biology ,Kidney ,Response Elements ,Transfection ,Cell Line ,Rats, Sprague-Dawley ,Mice ,Endocrinology ,Internal medicine ,Gene expression ,medicine ,Animals ,Humans ,Phosphorylation ,STAT3 ,Promoter Regions, Genetic ,Thyrotropin-Releasing Hormone ,Neurons ,Leptin receptor ,digestive, oral, and skin physiology ,Embryo, Mammalian ,Recombinant Proteins ,Rats ,DNA-Binding Proteins ,nervous system ,Gene Expression Regulation ,Hypothalamus ,biology.protein ,Mutagenesis, Site-Directed ,Trans-Activators ,Receptors, Leptin ,Signal transduction ,hormones, hormone substitutes, and hormone antagonists ,Paraventricular Hypothalamic Nucleus - Abstract
During starvation in rodents, the hypothalamic-pituitary-thyroid axis is down-regulated, resulting in low circulating thyroid hormone levels. This involves a reduction in hypothalamic TRH mRNA that is caused in part by a fall in serum leptin levels, which is sensed by neurons within the hypothalamus. The mechanism by which this regulation occurs is not fully understood. Here we show transfection data and in vivo evidence, suggesting that leptin can regulate trh gene expression via activation of intracellular signal transducer and activator of transcription 3 (STAT3) proteins in TRH neurons. In trh promoter assays using transfected cells, functional STAT3 proteins are required for maximal activation of the trh promoter by leptin. Consistent with this, the STAT3-binding site on the leptin receptor is also required for this regulation. Using double immunohistochemistry, we show that peripherally administered leptin rapidly stimulates STAT3 phosphorylation in approximately 40% of TRH neurons in the paraventricular nucleus of the hypothalamus (PVN) in rats. Detailed anatomical analyses reveal that the leptin-responsive TRH neurons are concentrated in the caudal region of the medial and periventricular parvocellular subnucleus of the PVN. Combined, our data show that only a subpopulation of TRH neurons in the PVN is leptin responsive and suggest that stimulation of hypothalamic trh gene expression by leptin involves activation of STAT3 and that this signaling pathway is important for regulation of the hypothalamic-pituitary-thyroid axis by leptin.
- Published
- 2004
41. Role of signal transducer and activator of transcription 3 in regulation of hypothalamic proopiomelanocortin gene expression by leptin
- Author
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Lihong Huo, Heike Münzberg, Anthony N. Hollenberg, Eduardo A. Nillni, and Christian Bjørbæk
- Subjects
Leptin ,Male ,STAT3 Transcription Factor ,endocrine system ,medicine.medical_specialty ,Pro-Opiomelanocortin ,Transcription, Genetic ,Hypothalamus ,Hypothalamus, Middle ,Receptors, Cell Surface ,Energy homeostasis ,Rats, Sprague-Dawley ,Mice ,Endocrinology ,Central melanocortin system ,Proopiomelanocortin ,Internal medicine ,medicine ,Animals ,Humans ,Phosphorylation ,STAT3 ,Promoter Regions, Genetic ,Neurons ,Leptin receptor ,Binding Sites ,biology ,digestive, oral, and skin physiology ,Brain ,Peptide Fragments ,Recombinant Proteins ,Rats ,DNA-Binding Proteins ,medicine.anatomical_structure ,nervous system ,Gene Expression Regulation ,STAT protein ,biology.protein ,Trans-Activators ,Receptors, Leptin ,hormones, hormone substitutes, and hormone antagonists - Abstract
Leptin acts on the brain to regulate body weight and neuroendocrine function. Proopiomelanocortin (POMC) neurons in the hypothalamus are important targets of leptin. These cells express the leptin receptor ObRb, and leptin can regulate POMC mRNA levels, but the cellular mechanisms by which this occurs is unknown. Here we show evidence that leptin stimulates pomc gene transcription via activation of intracellular signal transducer and activator of transcription 3 (STAT3) proteins. In pomc-promoter assays using transfected cells, leptin induces pomc promoter activity. Expression of dominant negative STAT3 strongly suppresses this effect. Furthermore, maximal activation requires the presence of the STAT3-binding site, tyrosine 1138, of ObRb. Mutational analysis identifies a 30-bp promoter element that is required for regulation by leptin. In rats, robust leptin-dependent induction of STAT3 phosphorylation is demonstrated in hypothalamic POMC neurons using double immunohistochemistry. In total, approximately 37% of POMC cells are positive for phospho-STAT3 after leptin treatment. Furthermore, leptin-responsive POMC neurons are concentrated in the rostral region of the hypothalamus. Combined, our data show that a subpopulation of POMC neurons is leptin-responsive and suggest that stimulation of hypothalamic pomc gene expression in these cells requires STAT3 activation. We speculate that STAT3 is critical for leptin-dependent effects on energy homeostasis that are mediated by the central melanocortin system.
- Published
- 2003
42. Over-Expression of Leptin Receptors in Hypothalamic POMC Neurons Increases Susceptibility to Diet-Induced Obesity.
- Author
-
Gamber, Kevin M., Lihong Huo, Sangdeuk Ha, Hairston, Joyce E., Greeley, Sarah, and Bjørbæk, Christian
- Subjects
- *
OBESITY , *LEPTIN receptors , *GENE expression , *NEURONS , *PHOSPHORYLATION , *BODY weight , *MESSENGER RNA - Abstract
Diet-induced obesity (DIO) in rodents is characterized by impaired activation of signal-transducer and activator of transcription 3 (STAT3) by leptin receptors (LepRb) within the hypothalamic arcuate nucleus. This signaling defect likely plays an important role in development of DIO. However, the neuro-chemical identity of the leptin-STAT3 resistant arcuate neurons has not been determined and the underlying mechanisms responsible for development of cellular leptin resistance remain unclear. To investigate this, we first measured arcuate gene expression of known key signaling components of the LepRb signaling pathway and tested whether specifically the critical arcuate pro-opiomelanocortin (POMC) neurons are resistant to LepRb-STAT3 signaling in mice given a high-fat-diet (HFD) compared to mice provided a low-fat control diet (LFD). We found that leptin-dependent STAT3 phosphorylation was decreased within POMC neurons of HFD mice. In addition, Leprb mRNA and suppressor of cytokine signaling 3 (Socs3) mRNA were elevated in the arcuate of HFD mice. To investigate whether increased LepRb expression per se in POMC neurons can influence development of DIO and Socs3 expression, we created mice that over-express LepRb selectively in POMC neurons (POMC-LepRb). No differences in body weight, fat mass or food intake were found between LFD POMC-LepRb mice and LFD controls. Surprisingly, body weight, fat mass and caloric intake of HFD POMC-LepRb mice was markedly higher than HFD control mice. In addition, arcuate Socs3 mRNA was increased in HFD POMC-LepRb mice compared to HFD controls. These data show that specifically POMC neurons of DIO mice are resistant to STAT3 activation by leptin, indicating that those cells might play a role in development of DIO. Furthermore, over-expression of LepRb selectively in POMC neurons increases susceptibility to the development of DIO. We propose a model where over-reactivity of the leptin-LepRb signaling system in arcuate neurons may play causal a role in development of diet-induced obesity. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
43. Regulation of Tat Acetylation and Transactivation Activity by the Microtubule-associated Deacetylase HDAC6.
- Author
-
Lihong Huo, Dengwen Li, Xiaoou Sun, Xingjuan Shi, Karna, Prasanthi, Wei Yang, Min Liu, Wentao Qiao, Aneja, Ritu, and Zhou, Jun
- Subjects
- *
ACETYLATION , *CELL communication , *GENETIC regulation , *PROMOTERS (Genetics) , *PROTEIN binding - Abstract
Reversible acetylation of Tat is critical for its transactivation activity toward HIV-1 transcription. However, the enzymes involved in the acetylation/deacetylation cycles have not been fully characterized. In this study, by yeast two-hybrid assay, we have discovered the histone deacetylase HDAC6 to be a binding partner of Tat. Our data show that HDAC6 interacts with Tat in the cytoplasm in a microtubule-dependent manner. In addition, HDAC6 deacetylates Tat at Lys-28 and thereby suppresses Tat-mediated transactivation of the HIV-1 promoter. Inactivation of HDAC6 promotes the interaction of Tat with cyclin T1 and leads to an increase in Tat transactivation activity. These findings establish HDAC6 as a Tat deacetylase and support a model in which Lys-28 deacetylation decreases Tat transactivation activity through affecting the ability of Tat to form a ribonucleoprotein complex with cyclin T1 and the transactivation-responsive RNA. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
44. The Tumor Suppressor CYLD Regulates Microtubule Dynamics and Plays a Role in Cell Migration.
- Author
-
Jinmin Gao, Lihong Huo, Xiaoou Sun, Min Liu, Dengwen Li, Jin-Tang Dong, and Jun Zhou
- Subjects
- *
TUMOR suppressor proteins , *CELL migration , *MICROTUBULES , *CYTOLOGY , *ORGANELLES - Abstract
The familial cylindromatosis tumor suppressor CYLD is known to contain three cytoskeleton-associated protein glycine-rich (CAP-Gly) domains, which exist in a number of microtubule-binding proteins and are responsible for their association with microtubules. However, it remains elusive whether CYLD interacts with microtubules and, if so, whether the interaction is mediated by the CAP-Gly domains. In this study, our data demonstrate that CYLD associates with microtubules both in cells and in vitro, and the first CAP-Gly domain of CYLD is mainly responsible for the interaction. Knockdown of cellular CYLD expression dramatically delays microtubule regrowth after nocodazole washout, indicating an activity for CYLD in promoting microtubule assembly. Our data further demonstrate that CYLD enhances tubulin polymerization into microtubules by lowering the critical concentration for microtubule assembly. In addition, we have identified by wound healing assay a critical role for CYLD in mediating cell migration and found that its first CAP-Gly domain is required for this activity. Thus CYLD joins a growing list of CAP-Gly domain-containing proteins that regulate microtubule dynamics and function. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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