Search

Mesothelial cells, in the outermost layer of internal organs, are essential for both organ development and homeostasis. Although the parietal mesothelial cell is the primary origin of mesothelioma that may highjack developmental signaling, the signaling pathways that orchestrate developing parietal mesothelial progenitor cell (MPC) behaviors, such as MPC pool expansion, maturation, and differentiation, are poorly understood. To address it, we established a robust protocol for culturing WT1 + MPCs isolated from developing pig and mouse parietal thorax. Quantitative qPCR and immunostaining analyses revealed that BMP4 facilitated MPC differentiation into smooth muscle cells (SMCs). In contrast, FGF2 significantly promoted MPC progenitor pool expansion but blocked the SMC differentiation. BMP4 and FGF2 counterbalanced these effects, but FGF2 had the dominant impact in the long-term culture. A Wnt activator, CHIR99021, was pivotal in MPC maturation to CALB2 + mesothelial cells, while BMP4 or FGF2 was limited. Our results demonstrated central pathways critical for mesothelial cell behaviors., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Hwang, Shimamura, Tanaka, Miura, Sawada, Sarmah, Shimizu, Kondo, Lee, Martini, Ninish, Yan, Yamada and Mori.)

The currently accepted intestinal epithelial cell organization model proposes that Lgr5 + crypt-base columnar (CBC) cells represent the sole intestinal stem cell (ISC) compartment. However, previous studies have indicated that Lgr5 + cells are dispensable for intestinal regeneration, leading to two major hypotheses: one favoring the presence of a quiescent reserve ISC and the other calling for differentiated cell plasticity. To investigate these possibilities, we studied crypt epithelial cells in an unbiased fashion via high-resolution single-cell profiling. These studies, combined with in vivo lineage tracing, show that Lgr5 is not a specific ISC marker and that stemness potential exists beyond the crypt base and resides in the isthmus region, where undifferentiated cells participate in intestinal homeostasis and regeneration following irradiation (IR) injury. Our results provide an alternative model of intestinal epithelial cell organization, suggesting that stemness potential is not restricted to CBC cells, and neither de-differentiation nor reserve ISC are drivers of intestinal regeneration., Competing Interests: Declaration of interests Dr. A.C. is the founder, equity holder, and consultant of DarwinHealth Inc., a company that has licensed some of the algorithms used in this manuscript from Columbia University. Columbia University is also an equity holder in DarwinHealth Inc., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In the prevailing model, Lgr5+ cells are the only intestinal stem cells (ISCs) that sustain homeostatic epithelial regeneration by upward migration of progeny through elusive upper crypt transit-amplifying (TA) intermediates. Here, we identify a proliferative upper crypt population marked by Fgfbp1, in the location of putative TA cells, that is transcriptionally distinct from Lgr5+ cells. Using a kinetic reporter for time-resolved fate mapping and Fgfbp1-CreER T2 lineage tracing, we establish that Fgfbp1+ cells are multi-potent and give rise to Lgr5+ cells, consistent with their ISC function. Fgfbp1+ cells also sustain epithelial regeneration following Lgr5+ cell depletion. We demonstrate that FGFBP1, produced by the upper crypt cells, is an essential factor for crypt proliferation and epithelial homeostasis. Our findings support a model in which tissue regeneration originates from upper crypt Fgfbp1+ cells that generate progeny propagating bi-directionally along the crypt-villus axis and serve as a source of Lgr5+ cells in the crypt base., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: To investigate the incidence rate, clinical characteristics, and prognosis of neonatal stroke in Shenzhen, China., Methods: Led by Shenzhen Children's Hospital, the Shenzhen Neonatal Data Collaboration Network organized 21 institutions to collect 36 cases of neonatal stroke from January 2020 to December 2022. The incidence, clinical characteristics, treatment, and prognosis of neonatal stroke in Shenzhen were analyzed., Results: The incidence rate of neonatal stroke in 21 hospitals from 2020 to 2022 was 1/15 137, 1/6 060, and 1/7 704, respectively. Ischemic stroke accounted for 75% (27/36); boys accounted for 64% (23/36). Among the 36 neonates, 31 (86%) had disease onset within 3 days after birth, and 19 (53%) had convulsion as the initial presentation. Cerebral MRI showed that 22 neonates (61%) had left cerebral infarction and 13 (36%) had basal ganglia infarction. Magnetic resonance angiography was performed for 12 neonates, among whom 9 (75%) had involvement of the middle cerebral artery. Electroencephalography was performed for 29 neonates, with sharp waves in 21 neonates (72%) and seizures in 10 neonates (34%). Symptomatic/supportive treatment varied across different hospitals. Neonatal Behavioral Neurological Assessment was performed for 12 neonates (33%, 12/36), with a mean score of (32±4) points. The prognosis of 27 neonates was followed up to around 12 months of age, with 44% (12/27) of the neonates having a good prognosis., Conclusions: Ischemic stroke is the main type of neonatal stroke, often with convulsions as the initial presentation, involvement of the middle cerebral artery, sharp waves on electroencephalography, and a relatively low neurodevelopment score. Symptomatic/supportive treatment is the main treatment method, and some neonates tend to have a poor prognosis.

Background & Aims: The intestinal epithelium functions both in nutrient absorption and as a barrier, separating the luminal contents from a network of vascular, fibroblastic, and immune cells underneath. After injury to the intestine, multiple cell populations cooperate to drive regeneration of the mucosal barrier, including lymphatic endothelial cells (LECs). A population of granulocytic immature myeloid cells (IMCs), marked by Hdc, participate in regeneration of multiple organs such as the colon and central nervous system, and their contribution to intestinal regeneration was investigated., Methods: By using male and female histidine decarboxylase (Hdc) green fluorescent reporter (GFP) mice, we investigated the role of Hdc + IMCs in intestinal regeneration after exposure to 12 Gy whole-body irradiation. The movement of IMCs was analyzed using flow cytometry and immunostaining. Ablation of Hdc + cells using the Hdc CreERT2 tamoxifen-inducible recombinase Cre system, conditional knockout of Prostaglandin-endoperoxidase synthase 2 (Ptgs2) in Hdc + cells using Hdc Cre ; Ptgs2 floxed mice, and visualization of LECs using Prox1 tdTomato mice also was performed. The role of microbial signals was investigated by knocking down mice gut microbiomes using antibiotic cocktail gavages., Results: We found that Hdc + IMCs infiltrate the injured intestine after irradiation injury and promote epithelial regeneration in part by modulating LEC activity. Hdc + IMCs express Ptgs2 (encoding cyclooxygenase-2/COX-2), and enables them to produce prostaglandin E 2 . Prostaglandin E 2 acts on the prostaglandin E 2 receptor 4 receptor (EP4) on LECs to promote lymphangiogenesis and induce the expression of proregenerative factors including R-spondin 3. Depletion of gut microbes leads to reduced intestinal regeneration by impaired recruitment of IMCs., Conclusions: Altogether, our results unveil a critical role for IMCs in intestinal repair by modulating LEC activity and implicate gut microbes as mediators of intestinal regeneration., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Celiac disease (CD) is an autoimmune disease in which intestinal inflammation is induced by dietary gluten. The means through which gluten-specific CD4 + T cell activation culminates in intraepithelial T cell (T-IEL)-mediated intestinal damage remain unclear. Here, we performed multiplexed single-cell analysis of intestinal and gluten-induced peripheral blood T cells from patients in different CD states and healthy controls. Untreated, active, and potential CD were associated with an enrichment of activated intestinal T cell populations, including CD4 + follicular T helper (T FH ) cells, regulatory T cells (T regs ), and natural CD8 + αβ and γδ T-IELs. Natural CD8 + αβ and γδ T-IELs expressing activating natural killer cell receptors (NKRs) exhibited a distinct TCR repertoire in CD and persisted in patients on a gluten-free diet without intestinal inflammation. Our data further show that NKR-expressing cytotoxic cells, which appear to mediate intestinal damage in CD, arise from a distinct NKR-expressing memory population of T-IELs. After gluten ingestion, both αβ and γδ T cell clones from this memory population of T-IELs circulated systemically along with gluten-specific CD4 + T cells and assumed a cytotoxic and activating NKR-expressing phenotype. Collectively, these findings suggest that cytotoxic T cells in CD are rapidly mobilized in parallel with gluten-specific CD4 + T cells after gluten ingestion.

The human respiratory epithelium is derived from a progenitor cell in the distal buds of the developing lung. These "bud tip progenitors" are regulated by reciprocal signaling with surrounding mesenchyme; however, mesenchymal heterogeneity and function in the developing human lung are poorly understood. We interrogated single-cell RNA sequencing data from multiple human lung specimens and identified a mesenchymal cell population present during development that is highly enriched for expression of the WNT agonist RSPO2, and we found that the adjacent bud tip progenitors are enriched for the RSPO2 receptor LGR5. Functional experiments using organoid models, explant cultures, and FACS-isolated RSPO2 + mesenchyme show that RSPO2 is a critical niche cue that potentiates WNT signaling in bud tip progenitors to support their maintenance and multipotency., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Clinical outcomes in colorectal cancer (CRC) correlate with T cell infiltrates, but the specific contributions of heterogenous T cell types remain unclear. To investigate the diverse function of T cells in CRC, we profiled 37,931 T cells from tumors and adjacent normal colon of 16 patients with CRC with respect to transcriptome, TCR sequence, and cell surface markers. Our analysis identified phenotypically and functionally distinguishable effector T cell types. We employed single-cell gene signatures from these T cell subsets to query the TCGA database to assess their prognostic significance. We found 2 distinct cytotoxic T cell types. GZMK+KLRG1+ cytotoxic T cells were enriched in CRC patients with good outcomes. GNLY+CD103+ cytotoxic T cells with a dysfunctional phenotype were not associated with good outcomes, despite coexpression of CD39 and CD103, markers that denote tumor reactivity. We found 2 distinct Treg subtypes associated with opposite outcomes. While total Tregs were associated with good outcomes, CD38+ Tregs were associated with bad outcomes independently of stage and possessed a highly suppressive phenotype, suggesting that they inhibit antitumor immunity in CRC. These findings highlight the potential utility of these subpopulations in predicting outcomes and support the potential for novel therapies directed at CD38+ Tregs or CD8+CD103+ T cells.

Background and Purpose: Eagle's syndrome is not uncommon in clinical work. Because of its atypical symptoms, it is easy to be misdiagnosed as other diseases, further leading to misdiagnosis and mistreatment. At present, there is no expert consensus or treatment guidelines for the disease. We evaluated the clinical characteristics and postoperative efficacy of 103 patients with Eagle's syndrome based on their clinical symptoms, radiological studies, and physical examination. Through the multicenter clinical study of Tongji Medical College and Dalian Medical University, we found some characteristics of Eagle's syndrome in operation and imaging., Methods: In total, 103 patients with Eagle's syndrome (treated from January 2010 to January 2020) were retrospectively enrolled. The postoperative curative effect was analyzed by three surgical methods: styloid process resection through the external cervical approach (styloid process could not be touched through the mouth or could be touched under the jaw or when the CT scan showed that the inclination angle was not large), tonsillectomy + styloidectomy, and preservation of the tonsil for styloidectomy (the styloid process bone could be touched directly during intraoral palpation or in whom the distal part of the styloid process could not be directly touched, but the CT scan showed that the bone inclined toward the oropharynx and its distal part was relatively close to the oropharynx cavity; whether tonsillectomy was performed depended on whether the patient's tonsil was too large to affect the surgical incision). According to the Quality of Well-Being Scale (QWB), we calculated the W value of the scale before operation and 30 days, 3 months, 6 months and 12 months after operation, and compared the W value of each group., Results: The average length of the styloid process was 33 mm (range 25-61 mm). The patients were followed up for 12-36 months (average 15 months). Of the 103 patients, 21 underwent styloid process resection through the external cervical approach, 49 underwent tonsillectomy and styloidectomy, and 33 underwent styloidectomy with preservation of the tonsil. The treatment cured 48 (46%) cases, was effective in 35 (34%) and was ineffective in 20 (20%). The R language 3.6.3 software was used to perform the nonparametric rank sum test, differences in characteristics between groups were analyzed using the Kruskal-Wallis test with Dunn post hoc tests ( R package FSA) for categorical variables, and there was no significant difference between the three types of operations (H = 0.491, P = 0.782). QWB showed that the quality of life after operation was improved compared with that before operation., Conclusions: Operation is an effective method for treating Eagle's syndrome. There were no significant differences between the effects of the intraoral and external cervical approaches. Imaging examination-especially CT scanning and 3D reconstruction of the styloid process-is very helpful for diagnosis, but not an absolute criterion for the selection of surgery protocol., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The microbiome is an emerging key co-factor in the development of esophageal cancer, the sixth leading cause of cancer death worldwide. However, there is a paucity of data delineating how the microbiome contributes to the pathobiology of the two histological subtypes of esophageal cancer: esophageal squamous cell carcinoma and esophageal adenocarcinoma. This critical knowledge gap is partially due to inadequate modeling of host-microbiome interactions in the etiology of esophageal cancers. Recent advances have enabled progress in this field. Three dimensional (3D) organoids faithfully recapitulate the structure and function of the normal, preneoplastic, and neoplastic epithelia of the esophagus ex vivo and serve as a platform translatable for applications in precision medicine. Elsewhere in the gastrointestinal (GI) tract, the co-culture of 3D organoids with the bacterial microbiome has fostered insight into the pathogenic role of the microbiome in other GI cancers. Herein, we will summarize our current understanding of the relationship between the microbiome and esophageal cancer, discuss 3D organoid models of esophageal homeostasis, review analogous models of host-microbiome interactions in other GI cancers, and advocate for the application of these models to esophageal cancers. Together, we present a promising, novel approach with the potential to ameliorate the burden of esophageal cancer-related morbidity and mortality via improved prevention and therapeutic interventions.

Knowledge of the development and hierarchical organization of tissues is key to understanding how they are perturbed in injury and disease, as well as how they may be therapeutically manipulated to restore homeostasis. The rapidly regenerating intestinal epithelium harbors diverse cell types and their lineage relationships have been studied using numerous approaches, from classical label-retaining and genetic lineage tracing methods to novel transcriptome-based annotations. Here, we describe the developmental trajectories that dictate differentiation and lineage specification in the intestinal epithelium. We focus on the most recent single-cell RNA-sequencing (scRNA-seq)-based strategies for understanding intestinal epithelial cell lineage relationships, underscoring how they have refined our view of the development of this tissue and highlighting their advantages and limitations. We emphasize how these technologies have been applied to understand the dynamics of intestinal epithelial cells in homeostatic and injury-induced regeneration models.

The enteric neurotransmitter acetylcholine governs important intestinal epithelial secretory and immune functions through its actions on epithelial muscarinic Gq-coupled receptors such as M3R. Its role in the regulation of intestinal stem cell function and differentiation, however, has not been clarified. Here, we find that nonselective muscarinic receptor antagonism in mice as well as epithelial-specific ablation of M3R induces a selective expansion of DCLK1-positive tuft cells, suggesting a model of feedback inhibition. Cholinergic blockade reduces Lgr5-positive intestinal stem cell tracing and cell number. In contrast, Prox1-positive endocrine cells appear as primary sensors of cholinergic blockade inducing the expansion of tuft cells, which adopt an enteroendocrine phenotype and contribute to increased mucosal levels of acetylcholine. This compensatory mechanism is lost with acute irradiation injury, resulting in a paucity of tuft cells and acetylcholine production. Thus, enteroendocrine tuft cells appear essential to maintain epithelial homeostasis following modifications of the cholinergic intestinal niche.

Emerging single-cell technologies, like single-cell RNA sequencing (scRNA-seq), enable the study of heterogeneous biological systems at cellular resolution. By profiling the set of expressed transcripts in each cell, single-cell transcriptomics has allowed for the cataloging of the cellular constituents of multiple organs and tissues, both in health and disease. In addition, these technologies have provided mechanistic insights into cellular function, cell state transitions, developmental trajectories and lineage relationships, as well as helped to dissect complex, population-level responses to environmental perturbations. scRNA-seq is particularly useful for characterizing the intestinal epithelium because it is a dynamic, rapidly self-renewing tissue comprised of more than a dozen specialized cell types. Here we discuss the fundamentals of single-cell transcriptomics of the murine small intestinal epithelium. We review the principles of proper experimental design and provide methods for the dissociation of the small intestinal epithelium into single cells followed by fluorescence-activated cell sorting (FACS) and for scRNA-seq using the 10× Genomics Chromium platform.

Single-cell RNA-sequencing (scRNA-seq) provides a unique opportunity to study heterogeneous cell populations within tissues, including the intestinal epithelium, to gain detailed molecular insights into their biology. Many new putative markers of intestinal stem cells and their progeny have been described using single-cell transcriptomics, which has contributed to the identification of novel subpopulations of mature cell types and insight into their developmental trajectories. This approach has revealed tremendous cellular heterogeneity within the intestinal epithelium that is concordant with its diverse and multifaceted functions. We discuss the function of these subpopulations during tissue homeostasis, as well as putative subpopulations with inducible regenerative potential following tissue injury.

Background & Aims: Intestinal crypts have a remarkable capacity to regenerate after injury from loss of crypt base columnar (CBC) stem cells. After injury, facultative stem cells (FSCs) are activated to replenish the epithelium and replace lost CBCs. Our aim was to assess the role of insulin-like growth factor-1 (IGF-1) to activate FSCs for crypt repair., Methods: The intestinal regenerative response was measured after whole body 12-Gy γ-irradiation of adult mice. IGF-1 signaling or its downstream effector mammalian target of rapamycin complex 1 (mTORC1) was inhibited by administering BMS-754807 or rapamycin, respectively. Mice with inducible Rptor gene deletion were studied to test the role of mTORC1 signaling in the intestinal epithelium. FSC activation post-irradiation was measured by lineage tracing., Results: We observed a coordinate increase in growth factor expression, including IGF-1, at 2 days post-irradiation, followed by a surge in mTORC1 activity during the regenerative phase of crypt repair at day 4. IGF-1 was localized to pericryptal mesenchymal cells, and IGF-1 receptor was broadly expressed in crypt progenitor cells. Inhibition of IGF-1 signaling via BMS-754807 treatment impaired crypt regeneration after 12-Gy irradiation, with no effect on homeostasis. Similarly, rapamycin inhibition of mTORC1 during the growth factor surge blunted the regenerative response. Analysis of Villin-CreER T2 ;Rptor fl/fl mice showed that epithelial mTORC1 signaling was essential for crypt regeneration. Lineage tracing from Bmi1-marked cells showed that rapamycin blocked FSC activation post-irradiation., Conclusions: Our study shows that IGF-1 signaling through mTORC1 drives crypt regeneration. We propose that IGF-1 release from pericryptal cells stimulates mTORC1 in FSCs to regenerate lost CBCs., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background & Aims: The intestinal epithelium is maintained by long-lived intestinal stem cells (ISCs) that reside near the crypt base. Above the ISC zone, there are short-lived progenitors that normally give rise to lineage-specific differentiated cell types but can dedifferentiate into ISCs in certain circumstances. However, the role of epithelial dedifferentiation in cancer development has not been fully elucidated., Methods: We performed studies with Bhlha15-CreERT, Lgr5-DTR-GFP, Apc flox/flox , LSL-Notch (IC), and R26-reporter strains of mice. Some mice were given diphtheria toxin to ablate Lgr5-positive cells, were irradiated, or were given 5-fluorouracil, hydroxyurea, doxorubicin, or dextran sodium sulfate to induce intestinal or colonic tissue injury. In intestinal tissues, we analyzed the fate of progeny that expressed Bhlha15. We used microarrays and reverse-transcription PCR to analyze gene expression patterns in healthy and injured intestinal tissues and in tumors. We analyzed gene expression patterns in human colorectal tumors using The Cancer Genome Atlas data set., Results: Bhlha15 identified Paneth cells and short-lived secretory precursors (including pre-Paneth label-retaining cells) located just above the ISC zone in the intestinal epithelium. Bhlha15 + cells had no plasticity after loss of Lgr5-positive cells or irradiation. However, Bhlha15 + secretory precursors started to supply the enterocyte lineage after doxorubicin-induced epithelial injury in a Notch-dependent manner. Sustained activation of Notch converts Bhlha15 + secretory precursors to long-lived enterocyte progenitors. Administration of doxorubicin and expression of an activated form of Notch resulted in a gene expression pattern associated with enterocyte progenitors, whereas only sustained activation of Notch altered gene expression patterns in Bhlha15 + precursors toward those of ISCs. Bhlha15 + enterocyte progenitors with sustained activation of Notch formed intestinal tumors with serrated features in mice with disruption of Apc. In the colon, Bhlha15 marked secretory precursors that became stem-like, cancer-initiating cells after dextran sodium sulfate-induced injury, via activation of Src and YAP signaling. In analyses of human colorectal tumors, we associated activation of Notch with chromosome instability-type tumors with serrated features in the left colon., Conclusions: In mice, we found that short-lived precursors can undergo permanent reprogramming by activation of Notch and YAP signaling. These cells could mediate tumor formation in addition to traditional ISCs., (Copyright © 2019. Published by Elsevier Inc.)

Background: Hepatitis B virus (HBV) infection is strongly associated with hepatocellular carcinoma due to the main pathogenic X protein of HBV (HBx). Whether HBV infection and the HBx protein could result in macular degeneration (MD) is not known. The aim of this study is to assess the association and underlying mechanisms between HBV infection and MD., Methods: The National Health Research Institutes in Taiwan built a large database, the National Health Insurance Research Database (NHIRD), which includes the claims data from the Taiwan National Health Insurance (NHI) program. The Taiwan NHI is a single-payer, compulsory health insurance program for Taiwan citizens. The data for the present study were derived from the Longitudinal Health Insurance Database, which contains the claims data of 1 million insured people within the NHIRD, including beneficiary registration, inpatient and outpatient files, drug use, and other medical services. In this study, we first investigated the association of HBV infection and the risk of MD by a population-based cohorts study enrolling 39,796 HBV-infected patients and 159,184 non-HBV-infected patients., Results: After adjustment of age, sex, and comorbidities, the risk of MD was significantly higher in the HBV-infected cohort than in the non-HBV-infected cohort (adjusted HR = 1.31; 95% CI = 1.17-1.46). In vitro, we provided evidence to demonstrate that overexpression of HBx in the human retinal pigment epithelial (RPE) cell line, ARPE19, significantly reduced cell viability and clonogenic survival upon UV and blue light irradiation. By gene microarray analysis, we further showed that almost all genes in DNA repair pathways including base excision repair, nucleotide excision repair, mismatch repair, and homologous recombination were significantly down-regulated in the UV-induced cell death of HBx-transfected ARPE19 cells., Conclusions: The HBx protein may sensitize RPE cells to UV and blue light irradiation and increase the risk of HBV-infection-associated MD through down-regulation of multiple DNA repair pathways.

Distinct stem/progenitor cells generate intestinal epithelium during fetal and postnatal life. In a recent issue of Nature, Nusse and Savage et al. use helminth infection to show that Lgr5 + intestinal stem cells are replaced by fetal-like progenitors following injury, suggesting that some fetal developmental pathways are repurposed during injury-induced tissue regeneration., (Copyright © 2018. Published by Elsevier Inc.)

Dclk1 -expressing tuft cells constitute a unique intestinal epithelial lineage that is distinct from enterocytes, Paneth cells, goblet cells, and enteroendocrine cells. Tuft cells express taste-related receptors and distinct transcription factors and interact closely with the enteric nervous system, suggesting a chemosensory cell lineage. In addition, recent work has shown that tuft cells interact closely with cells of the immune system, with a critical role in the cellular regulatory network governing responses to luminal parasites. Importantly, ablation of tuft cells severely impairs epithelial proliferation and tissue regeneration after injury, implicating tuft cells in the modulation of epithelial stem/progenitor function. Finally, tuft cells expand during chronic inflammation and in preneoplastic tissues, suggesting a possible early role in inflammation-associated tumorigenesis. Hence, we outline and discuss emerging evidence that strongly supports tuft cells as key regulatory cells in the complex network of the intestinal microenvironment., (Copyright © 2017 the American Physiological Society.)

Several cell populations have been reported to possess intestinal stem cell (ISC) activity during homeostasis and injury-induced regeneration. Here, we explored inter-relationships between putative mouse ISC populations by comparative RNA-sequencing (RNA-seq). The transcriptomes of multiple cycling ISC populations closely resembled Lgr5 + ISCs, the most well-defined ISC pool, but Bmi1-GFP + cells were distinct and enriched for enteroendocrine (EE) markers, including Prox1. Prox1-GFP + cells exhibited sustained clonogenic growth in vitro, and lineage-tracing of Prox1 + cells revealed long-lived clones during homeostasis and after radiation-induced injury in vivo. Single-cell mRNA-seq revealed two subsets of Prox1-GFP + cells, one of which resembled mature EE cells while the other displayed low-level EE gene expression but co-expressed tuft cell markers, Lgr5 and Ascl2, reminiscent of label-retaining secretory progenitors. Our data suggest that the EE lineage, including mature EE cells, comprises a reservoir of homeostatic and injury-inducible ISCs, extending our understanding of cellular plasticity and stemness., (Copyright © 2017 Elsevier Inc. All rights reserved.)

A 59 years old woman with chief complain of intermittent hemoptysis and shortness of breath was admitted to our hospital. Fiberoptic laryngoscope: no abnormality seen; enhanced computerized tomography of the neck showed that at the second trachea ring located a round nodule with a diameter of about 23 mm, flat on the sixth cervical vertebrae, consider vascular tumors. The immunohistochemistry: an inflammatory myofibroblastic tumor., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.)

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, catalyzes tri-methylation of histone H3 at Lys 27 (H3K27me3) to regulate gene expression through epigenetic machinery. EZH2 functions as a double-facet molecule in regulation of gene expression via repression or activation mechanisms, depending on the different cellular contexts. EZH2 interacts with both histone and non-histone proteins to modulate diverse physiological functions including cancer progression and malignancy. In this review article, we focused on the updated information regarding microRNAs (miRNAs) and long non coding RNAs (lncRNAs) in regulation of EZH2, the oncogenic and tumor suppressive roles of EZH2 in cancer progression and malignancy, as well as current pre-clinical and clinical trials of EZH2 inhibitors., Competing Interests: The authors declare no conflict of interest.

The canonical Wnt/β-catenin signalling pathway governs diverse developmental, homeostatic and pathological processes. Palmitoylated Wnt ligands engage cell-surface frizzled (FZD) receptors and LRP5 and LRP6 co-receptors, enabling β-catenin nuclear translocation and TCF/LEF-dependent gene transactivation. Mutations in Wnt downstream signalling components have revealed diverse functions thought to be carried out by Wnt ligands themselves. However, redundancy between the 19 mammalian Wnt proteins and 10 FZD receptors and Wnt hydrophobicity have made it difficult to attribute these functions directly to Wnt ligands. For example, individual mutations in Wnt ligands have not revealed homeostatic phenotypes in the intestinal epithelium-an archetypal canonical, Wnt pathway-dependent, rapidly self-renewing tissue, the regeneration of which is fueled by proliferative crypt Lgr5 + intestinal stem cells (ISCs). R-spondin ligands (RSPO1-RSPO4) engage distinct LGR4-LGR6, RNF43 and ZNRF3 receptor classes, markedly potentiate canonical Wnt/β-catenin signalling, and induce intestinal organoid growth in vitro and Lgr5 + ISCs in vivo. However, the interchangeability, functional cooperation and relative contributions of Wnt versus RSPO ligands to in vivo canonical Wnt signalling and ISC biology remain unknown. Here we identify the functional roles of Wnt and RSPO ligands in the intestinal crypt stem-cell niche. We show that the default fate of Lgr5 + ISCs is to differentiate, unless both RSPO and Wnt ligands are present. However, gain-of-function studies using RSPO ligands and a new non-lipidated Wnt analogue reveal that these ligands have qualitatively distinct, non-interchangeable roles in ISCs. Wnt proteins are unable to induce Lgr5 + ISC self-renewal, but instead confer a basal competency by maintaining RSPO receptor expression that enables RSPO ligands to actively drive and specify the extent of stem-cell expansion. This functionally non-equivalent yet cooperative interaction between Wnt and RSPO ligands establishes a molecular precedent for regulation of mammalian stem cells by distinct priming and self-renewal factors, with broad implications for precise control of tissue regeneration.

Wnt proteins modulate cell proliferation and differentiation and the self-renewal of stem cells by inducing β-catenin-dependent signalling through the Wnt receptor frizzled (FZD) and the co-receptors LRP5 and LRP6 to regulate cell fate decisions and the growth and repair of several tissues. The 19 mammalian Wnt proteins are cross-reactive with the 10 FZD receptors, and this has complicated the attribution of distinct biological functions to specific FZD and Wnt subtype interactions. Furthermore, Wnt proteins are modified post-translationally by palmitoylation, which is essential for their secretion, function and interaction with FZD receptors. As a result of their acylation, Wnt proteins are very hydrophobic and require detergents for purification, which presents major obstacles to the preparation and application of recombinant Wnt proteins. This hydrophobicity has hindered the determination of the molecular mechanisms of Wnt signalling activation and the functional importance of FZD subtypes, and the use of Wnt proteins as therapeutic agents. Here we develop surrogate Wnt agonists, water-soluble FZD-LRP5/LRP6 heterodimerizers, with FZD5/FZD8-specific and broadly FZD-reactive binding domains. Similar to WNT3A, these Wnt agonists elicit a characteristic β-catenin signalling response in a FZD-selective fashion, enhance the osteogenic lineage commitment of primary mouse and human mesenchymal stem cells, and support the growth of a broad range of primary human organoid cultures. In addition, the surrogates can be systemically expressed and exhibit Wnt activity in vivo in the mouse liver, regulating metabolic liver zonation and promoting hepatocyte proliferation, resulting in hepatomegaly. These surrogates demonstrate that canonical Wnt signalling can be activated by bi-specific ligands that induce receptor heterodimerization. Furthermore, these easily produced, non-lipidated Wnt surrogate agonists facilitate functional studies of Wnt signalling and the exploration of Wnt agonists for translational applications in regenerative medicine.

Wnt signalling is involved in multiple aspects of embryonic development and adult tissue homeostasis, notably via controlling cellular proliferation and differentiation. Wnt signalling is subject to stringent positive and negative regulation to promote proper development and homeostasis yet avoid aberrant growth. Such multi-layer regulation includes post-translational modification and processing of Wnt proteins themselves, R-spondin (Rspo) amplification of Wnt signalling, diverse receptor families, and intracellular and extracellular antagonists and destruction and transcription complexes. In the gastrointestinal tract, Wnt signalling is crucial for development and renewal of the intestinal epithelium. Intestinal stem cells (ISCs) undergo symmetric division and neutral drift dynamics to renew the intestinal epithelium. Sources of Wnts and Wnt amplifers such as R-spondins are beginning to be elucidated as well as their functional contribution to intestinal homeostasis. In this review we focus on regulation of ISCs and intestinal homeostasis by the Wnt/Rspo pathway, the potential cellular sources of Wnt signalling regulators and highlight potential future areas of study., (© 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.)

Our sense of taste can be influenced by our other senses, with several groups having explored the effects of olfactory, visual, or tactile stimulation on what we perceive as taste. Research into multisensory, or crossmodal perception has rarely linked our sense of taste with that of audition. In our study, 48 participants in a crossover experiment sampled multiple concentrations of solutions of 5 prototypic tastants, during conditions with or without broad spectrum auditory stimulation, simulating that of airline cabin noise. Airline cabins are an unusual environment, in which food is consumed routinely under extreme noise conditions, often over 85 dB, and in which the perceived quality of food is often criticized. Participants rated the intensity of solutions representing varying concentrations of the 5 basic tastes on the general Labeled Magnitude Scale. No difference in intensity ratings was evident between the control and sound condition for salty, sour, or bitter tastes. Likewise, panelists did not perform differently during sound conditions when rating tactile, visual, or auditory stimulation, or in reaction time tests. Interestingly, sweet taste intensity was rated progressively lower, whereas the perception of umami taste was augmented during the experimental sound condition, to a progressively greater degree with increasing concentration. We postulate that this effect arises from mechanostimulation of the chorda tympani nerve, which transits directly across the tympanic membrane of the middle ear., ((c) 2015 APA, all rights reserved).)

Ascl2 is a Wnt-responsive master transcription factor that controls the Lgr5(+) intestinal stem cell gene expression program. Now in Cell Stem Cell, Schuijers et al. (2015) report an Ascl2 positive feedback loop, tuned by previous Wnt pathway activity, that perpetuates intestinal stem cell identity in response to Wnt/R-spondin stimulation., (Copyright © 2015 Elsevier Inc. All rights reserved.)

How are skeletal tissues derived from skeletal stem cells? Here, we map bone, cartilage, and stromal development from a population of highly pure, postnatal skeletal stem cells (mouse skeletal stem cells, mSSCs) to their downstream progenitors of bone, cartilage, and stromal tissue. We then investigated the transcriptome of the stem/progenitor cells for unique gene-expression patterns that would indicate potential regulators of mSSC lineage commitment. We demonstrate that mSSC niche factors can be potent inducers of osteogenesis, and several specific combinations of recombinant mSSC niche factors can activate mSSC genetic programs in situ, even in nonskeletal tissues, resulting in de novo formation of cartilage or bone and bone marrow stroma. Inducing mSSC formation with soluble factors and subsequently regulating the mSSC niche to specify its differentiation toward bone, cartilage, or stromal cells could represent a paradigm shift in the therapeutic regeneration of skeletal tissues., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Multiple culture techniques now exist for the long-term maintenance of neonatal primary murine intestinal organoids in vitro; however, the achievement of contractile behavior within cultured organoids has thus far been infrequent and unpredictable. Here we combine finite element simulation of oxygen transport and quantitative comparative analysis of cellular microenvironments to elucidate the critical variables that promote reproducible intestinal organoid contraction. Experimentally, oxygen distribution was manipulated by adjusting the ambient oxygen concentration along with the use of semi-permeable membranes to enhance transport. The culture microenvironment was further tailored through variation of collagen type-I matrix density, addition of exogenous R-spondin1, and specification of culture geometry. "Air-liquid interface" cultures resulted in significantly higher numbers of contractile cultures relative to traditional submerged cultures. These interface cultures were confirmed to have enhanced and more symmetric oxygen transport relative to traditional submerged cultures. While oxygen availability was found to impact in vitro contraction rate and the orientation of contractile movement, it was not a key factor in enabling contractility. For all conditions tested, reproducible contractile behavior only occurred within a consistent and narrow range of collagen type-I matrix densities with porosities of approximately 20% and storage moduli near 30 Pa. This suggests that matrix density acts as a "permissive switch" that enables contractions to occur. Similarly, contractions were only observed in cultures with diameters less than 15.5 mm that had relatively large interfacial surface area between the compliant matrix and the rigid culture dish. Taken together, these data suggest that spatial geometry and mechanics of the microenvironment, which includes both the encapsulating matrix as well as the surrounding culture device, may be key determinants of intestinal organoid functionality. As peristaltic contractility is a crucial requirement for normal digestive tract function, this achievement of reproducible organoid contraction marks a pivotal advancement towards engineering physiologically functional replacement tissue constructs.

Neuroimaging studies suggest that the neural network involved in language control may not be specific to bi-/multilingualism but is part of a domain-general executive control system. We report a trilingual case of a Cantonese (L1), English (L2), and Mandarin (L3) speaker, Dr. T, who sustained a brain injury at the age of 77 causing lesions in the left frontal lobe and in the left temporo-parietal areas resulting in fluent aphasia. Dr. T's executive functions were impaired according to a modified version of the Stroop color-word test and the Wisconsin Card Sorting Test performance was characterized by frequent perseveration errors. Dr. T demonstrated pathological language switching and mixing across her three languages. Code switching in Cantonese was more prominent in discourse production than confrontation naming. Our case suggests that voluntary control of spoken word production in trilingual speakers shares neural substrata in the frontobasal ganglia system with domain-general executive control mechanisms. One prediction is that lesions to such a system would give rise to both pathological switching and impairments of executive functions in trilingual speakers.

The skin is a classical example of a tissue maintained by stem cells. However, the identity of the stem cells that maintain the interfollicular epidermis and the source of the signals that control their activity remain unclear. Using mouse lineage tracing and quantitative clonal analyses, we showed that the Wnt target gene Axin2 marks interfollicular epidermal stem cells. These Axin2-expressing cells constitute the majority of the basal epidermal layer, compete neutrally, and require Wnt/β-catenin signaling to proliferate. The same cells contribute robustly to wound healing, with no requirement for a quiescent stem cell subpopulation. By means of double-labeling RNA in situ hybridization in mice, we showed that the Axin2-expressing cells themselves produce Wnt signals as well as long-range secreted Wnt inhibitors, suggesting an autocrine mechanism of stem cell self-renewal.

A remarkable feature of regenerative processes is their ability to halt proliferation once an organ's structure has been restored. The Wnt signalling pathway is the major driving force for homeostatic self-renewal and regeneration in the mammalian intestine. However, the mechanisms that counterbalance Wnt-driven proliferation are poorly understood. Here we demonstrate in mice and humans that yes-associated protein 1 (YAP; also known as YAP1)--a protein known for its powerful growth-inducing and oncogenic properties--has an unexpected growth-suppressive function, restricting Wnt signals during intestinal regeneration. Transgenic expression of YAP reduces Wnt target gene expression and results in the rapid loss of intestinal crypts. In addition, loss of YAP results in Wnt hypersensitivity during regeneration, leading to hyperplasia, expansion of intestinal stem cells and niche cells, and formation of ectopic crypts and microadenomas. We find that cytoplasmic YAP restricts elevated Wnt signalling independently of the AXIN-APC-GSK-3β complex partly by limiting the activity of dishevelled (DVL). DVL signals in the nucleus of intestinal stem cells, and its forced expression leads to enhanced Wnt signalling in crypts. YAP dampens Wnt signals by restricting DVL nuclear translocation during regenerative growth. Finally, we provide evidence that YAP is silenced in a subset of highly aggressive and undifferentiated human colorectal carcinomas, and that its expression can restrict the growth of colorectal carcinoma xenografts. Collectively, our work describes a novel mechanistic paradigm for how proliferative signals are counterbalanced in regenerating tissues. Additionally, our findings have important implications for the targeting of YAP in human malignancies.

Background and Aim of the Study: The quantification of incidentally found aortic valve calcification on computed tomography (CT) is not performed routinely, as data relating to the accuracy of aortic valve calcium for estimating the severity of aortic stenosis (AS) is neither consistent nor validated. As aortic valve calcium quantification by CT is confounded by wall and coronary ostial calcification, as well as motion artifact, the ex-vivo micro-computed tomography (micro-CT) of stenotic aortic valves allows a precise measurement of the amounts of calcium present. The study aim, using excised aortic valves from patients with confirmed AS, was to determine if the amount of calcium on micro-CT correlated with the severity of AS., Methods: Each of 35 aortic valves that had been excised from patients during surgical valve replacement were examined using micro-CT imaging. The amount of calcium present was determined by absolute and proportional values of calcium volume in the specimen. Subsequently, the correlation between calcium volume and preoperative mean aortic valve gradient (MAVG), peak transaortic velocity (V(max)), and aortic valve area (AVA) on echocardiography, was evaluated., Results: The mean calcium volume across all valves was 603.2 +/- 398.5 mm3, and the mean ratio of calcium volume to total valve volume was 0.36 +/- 0.16. The mean aortic valve gradient correlated positively with both calcium volume and ratio (r = 0.72, p < 0.001). V(max) also correlated positively with the calcium volume and ratio (r = 0.69 and 0.76 respectively; p < 0.001). A logarithmic curvilinear model proved to be the best fit to the correlation. A calcium volume of 480 mm3 showed sensitivity and specificity of 0.76 and 0.83, respectively, for a diagnosis of severe AS, while a calcium ratio of 0.37 yielded sensitivity and specificity of 0.82 and 0.94, respectively., Conclusion: A radiological estimation of calcium amount by volume, and its proportion to the total valve volume, were shown to serve as good predictive parameters for severe AS. An estimation of the calcium volume may serve as a complementary measure for determining the severity of AS when aortic valve calcification is identified on CT imaging.

The small intestine epithelium undergoes rapid and continuous regeneration supported by crypt intestinal stem cells (ISCs). Bmi1 and Lgr5 have been independently identified to mark long-lived multipotent ISCs by lineage tracing in mice; however, the functional distinctions between these two populations remain undefined. Here, we demonstrate that Bmi1 and Lgr5 mark two functionally distinct ISCs in vivo. Lgr5 marks mitotically active ISCs that exhibit exquisite sensitivity to canonical Wnt modulation, contribute robustly to homeostatic regeneration, and are quantitatively ablated by irradiation. In contrast, Bmi1 marks quiescent ISCs that are insensitive to Wnt perturbations, contribute weakly to homeostatic regeneration, and are resistant to high-dose radiation injury. After irradiation, however, the normally quiescent Bmi1(+) ISCs dramatically proliferate to clonally repopulate multiple contiguous crypts and villi. Clonogenic culture of isolated single Bmi1(+) ISCs yields long-lived self-renewing spheroids of intestinal epithelium that produce Lgr5-expressing cells, thereby establishing a lineage relationship between these two populations in vitro. Taken together, these data provide direct evidence that Bmi1 marks quiescent, injury-inducible reserve ISCs that exhibit striking functional distinctions from Lgr5(+) ISCs and support a model whereby distinct ISC populations facilitate homeostatic vs. injury-induced regeneration.

Background: Transcatheter aortic valves were developed as an alternative to surgery for the one third to two thirds of patients with severe aortic stenosis who do not undergo aortic valve replacement. In this study, we examined reasons for medical management of aortic stenosis in relation to operative risks and outcomes for veterans with and without valve replacement., Methods: The echocardiography database was screened from 2000 to 2007 for severe aortic stenosis. The Society of Thoracic Surgeons risk scores and survival were determined for patients with and without aortic valve replacement., Results: Of 132 severe aortic stenosis patients included, 42% were medically managed. Predicted operative mortality risk was lower for surgical patients than for medical patients (4.5%±4.2% versus 6.8%±5.1%, p=0.002). Overall, the most common reason for medical management of aortic stenosis was assumption that the patient was high risk for surgery (30.4%). The surgery group had significantly higher median survival (92.2 versus 32.4 months) and 5-year survival (71% versus 37%, p<0.001) than the medical group. Cardiac surgery was not consulted in 61% of medically managed patients, of whom only 18% had Society of Thoracic Surgeons risk score of 10 or greater. Aortic valve replacement was an independent predictor of lower mortality (hazard ratio 0.43, p=0.008)., Conclusions: Although operative risk was higher among patients who did not undergo surgery, most were not the 10% or greater required for transcatheter valves. Given the significantly lower survival with medical therapy, aortic valve replacement should be carefully considered for most severe aortic stenosis patients whereas transcatheter aortic valves should be reserved for patients with high operative risks., (Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

A novel elementary osmotic pump tablet was developed. The system uses the core of drug-resin complexes (DRCs) loaded with propranolol hydrochloride (PNH) for time-controlled delivery. In traditional osmotic pump tablets (OPTs), the lag time was always minimized. However, in the DRCs osmotic pump tablet (DRCOPT), the lag time was increased to achieve the time-controlled delivery. The quantity of osmotic agent in the core and channeling agent in the coating solution as well as weight gain were confirmed to be essential for the release behavior. A spherical symmetric design was applied to the optimization of the DRCOPT. The optimal formulation mainly consisted of DRC 100 mg, polyethyleneoxide (N80) 182 mg, and NaCl 30 mg. The ratio of cellulose acetate (CA)/polyethylene glycol 4000 was 15:3 (w/w) in coating solution, and the weight gain was 8%. The release behavior of the optimal DRCOPT was evaluated in media with different pH, rotation speeds, and ionic strength. It was found to generate a 2-h lag time, to deliver PNH at a rate of zero order from 2 h to 14 h in the medium of NaCl 0.15 mol/l, and the cumulative release at 24 h was 94%. Drug relee was independent of pH and rotation speed, but was proportional to ionic strength. In summary, the lag time could be used in therapeutic regimens with the characteristics of chronotherapy because of the lag time and provides a new concept for the development of osmotic pumps.

The aim of the present work was to evaluate the transdermal permeability of pentoxifylline gel in vitro and in vivo. Gel was prepared with carbomer 934 as the base, and the Wistar rat was chosen as an animal model. The effects of percutaneous enhancers on the transdermal permeability of pentoxifylline gel were investigated by in vitro permeation experiments. Cumulative permeation at different times was determined by HPLC. 3% Azone and 5% propylene glycol were used as collaborative enhancers in an optimal formulation. Topical concentrations at different times were measured by microdialysis in vivo. The transdermal process of pentoxifylline fits to a zero-order kinetic equation, and its release profile remains of the zero-order despite the addition of enhancers. In addition, a good in-vitro-in-vivo correlation was achieved.

Aim: To study the effects of sodium salicylate on the expression of GABAalpha NR1 and hearing response properties of inferior colliculus neurons in mice., Methods: Thirty-six kunming mice were divided into three groups (A, B, C,). The expression of GABAalpha NR1 were measured by using RT-PCR. The intensity-rates functions, intensity-latency functions and frequency-turning curves were recorded by extracellular electrophysiological recording techniques., Results: (1) The expression of GABAalpha mRNA of B group was decreased remarkably than the control group (A group, P < 0.05), there weren't noticeable differences between A group and C group (P > 0.05). The expression of NR1 mRNA of B group was increased remarkably than the control group (A group, P < 0.01), there were noticeable differences between A group and C group P < 0.05). (2) The intensity-rates functions, intensity-latency functions were monotonic while the frequency-turning curves were more broad when sodium salicylate was given. (3) The intensity-rates functions, intensity-latency functions were non-monotonic while the frequency-turning curves were sharpened after lidocaine was given., Conclusions: (1) The results suggested that administration of sodium salicylate decreased the expression of GABAalpha while increased the expression of NR1mRNA. (2) The intensity-rates functions, intensity-latency functions were monotonic, the frequency-turning curves were more broad when salicylate was given and the changes above could be reversed by given lidocaine.

The effects of neuroglobin (NGB) gene transfer in vivo mediated by GeneJamer on the hearing response properties of the inferior colliculus (IC) neurons in mice after administration of sodium salicylate were studied. Forty-eight Kunming mice were divided into 4 groups (n=12 in each group): Group A1 (negative control);Group A2 (positive control);Group B, sodium salicylate (450 mg/kg every day) + pEGFP-C1;Group C, sodium salicylate (450 mg/kg every day) + pEGFP-NGB. The GeneJamer and pEGFP-NGB were mixed and injected into IC neurons in mice. The expression of NGB mRNA and protein of IC neurons in mice was detected by using RT-PCR and Western blot methods. The intensity-rate functions, intensity-latency functions and frequency-turning curves in IC neurons were recorded by extracellular electrophysiological recording techniques and the effects of pEGFP-NGB transfer following injection of sodium salicylate on them were studied. It was found that: (1) The GeneJamer-mediated pEGFP-NGB could be effectively transferred into the IC brain tissues in mice and NGB could be expressed intensively. (2) The intensity-rate functions of IC neurons were raised after administration of sodium salicylate. The non-monotonic styles of intensity-rate functions in groups A1, A2 and C were accounted for 74.6%, 72.2 %, 59.3 %, respectively, and the function in group B for 47%. There were significant differences between group B and groups A1, A2 or C (P<0.01, P<0.01, P<0.05). (3) The intensity-latency functions in IC neurons were reduced after administration of sodium salicylate. The non-monotonic styles of intensity-latency functions in groups A1, A2 and C were accounted for 3.2 %, 5.1 %and 21 %, respectively, and that in group B for 45.5 %. There were significant differences between group B and groups A1, A2 or C (P<0.01, P<0.01, P<0.05, respectively). (4) The frequency-turning curves in groups A1 and A2 were sharpened. In 72 acoustic neurons recorded in the group B, the frequency-turning curves from 53 neurons were broadened while those of the rest were sharpened. In group C the frequency-turning curves recorded from 12 of 67 acoustic neurons were broadened while those of the remaining were sharpened. These results suggest that in vivo transfer of NGB gene is highly expressed in IC neurons in mice. In vivo transfer of NGB gene reverses the change of intensity-rate functions, intensity-latency functions and the code styles after administration of sodium salicylate in IC neurons in mice.

Objective: To construct the adenoviral vector containing human Bcl-2 gene and to study the expression of the gene in the spiral ganglion cells (SGC) in vitro., Methods: Human Bcl-2 cDNA obtained from the plasmid pUC-CAGGS/Bcl-2 was cloned into the plasmid pAdTrack-CMV. Then, pAdTrack/Bcl-2 was cotransferred with adenoviral backbone vector into E. coli strain BJ5183. The recombinant adenoviral plasmid was identified by restriction analysis with Pac I and transfected into HEK293 cells to package and amplify recombinant adenovirus particles which would be identified by Electron microscope. After the adenovirus infected the rat spiral ganglion cells, the expression of Bcl-2 gene was detected by Western Blot and RT-PCR., Results: The recombinant AdEGFP/Bcl-2 plasmid was correctly constructed and confirmed by restriction endonuclease analysis. The viral particles in HEK293 cells were identified by Electron microscope. RT-PCR and Western blot showed that Bcl-2 gene was exactly transcripted and expressed in transgene SGC., Conclusions: The method based on homologous recombination in bacteria is simple and high efficient. The recombinant adenoviral vector containing human Bcl-2 cDNA was constructed and the transgene SGC expressed human Bcl-2 gene in vitro successfully. It provided foundation for the further study of protection for the impaired SGC by hBcl-2 gene.

The discovery of RNA-mediated gene-silencing pathways, including RNA interference, highlights a fundamental role of short RNAs in eukaryotic gene regulation and antiviral defence. Members of the Dicer and Argonaute protein families are essential components of these RNA-silencing pathways. Notably, these two families possess an evolutionarily conserved PAZ (Piwi/Argonaute/Zwille) domain whose biochemical function is unknown. Here we report the nuclear magnetic resonance solution structure of the PAZ domain from Drosophila melanogaster Argonaute 1 (Ago1). The structure consists of a left-handed, six-stranded beta-barrel capped at one end by two alpha-helices and wrapped on one side by a distinctive appendage, which comprises a long beta-hairpin and a short alpha-helix. Using structural and biochemical analyses, we demonstrate that the PAZ domain binds a 5-nucleotide RNA with 1:1 stoichiometry. We map the RNA-binding surface to the open face of the beta-barrel, which contains amino acids conserved within the PAZ domain family, and we define the 5'-to-3' orientation of single-stranded RNA bound within that site. Furthermore, we show that PAZ domains from different human Argonaute proteins also bind RNA, establishing a conserved function for this domain.

The notion that certain proteins lack intrinsic globular structure under physiological conditions and that the attainment of fully folded structure only occurs upon the binding of target molecules has been recently gaining popularity. We report here the solution structure of the PTB domain of the signaling protein Shc in the free form. Comparison of this structure with that of the complex form, obtained previously with a phosphopeptide ligand, reveals that the Shc PTB domain is structurally disordered in the free form, particularly around the regions constituting the peptide binding pocket. The binding of the ligand appears to reorganize this pocket through local folding events triggering a conformational switch between the free and the complex forms.

Membrane-anchored adaptor proteins FRS2alpha/beta (also known as SNT-1/2) mediate signaling of fibroblast growth factor receptors (FGFRs) and neurotrophin receptors (TRKs) through their N-terminal phosphotyrosine binding (PTB) domains. The FRS2 PTB domain recognizes tyrosine-phosphorylated TRKs at an NPXpY (where pY is phosphotyrosine) motif, whereas its constitutive association with FGFR involves a receptor juxtamembrane region lacking Tyr and Asn residues. Here we show by isothermal titration calorimetry that the FRS2alpha PTB domain binding to peptides derived from TRKs or FGFR is thermodynamically different. TRK binding is largely enthalpy-driven, whereas the FGFR interaction is governed by a favorable entropic contribution to the free energy of binding. Furthermore, our NMR spectral analysis suggests that disruption of an unstructured region C-terminal to the PTB domain alters local conformation and dynamics of the residues at the ligand-binding site, and that structural disruption of the beta8-strand directly weakens the PTB domain association with the FGFR ligand. Together, our new findings support a molecular mechanism by which conformational dynamics of the FRS2alpha PTB domain dictates its association with either fibroblast growth factor or neurotrophin receptors in neuronal development.

Phosphotyrosine binding (PTB) domains are structurally conserved modules found in proteins involved in numerous biological processes including signaling through cell-surface receptors and protein trafficking. While their original discovery is attributed to the recognition of phosphotyrosine in the context of NPXpY sequences -- a function distinct from that of the classical src homology 2 (SH2) domain -- recent studies show that these protein modules have much broader ligand binding specificities. These studies highlight the functional diversity of the PTB domain family as generalized protein interaction domains, and reinforce the concept that evolutionary changes of structural elements around the ligand binding site on a conserved structural core may endow these protein modules with the structural plasticity necessary for functional versatility.