24 results on '"Porter RL"'
Search Results
2. Differences in characteristics of people with and people without low back pain who participate in rotation-related sports.
- Author
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Porter RL, Scholtes SA, and Van Dillen L
- Published
- 2009
3. Disruption of cellular plasticity by repeat RNAs in human pancreatic cancer.
- Author
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You E, Danaher P, Lu C, Sun S, Zou L, Phillips IE, Rojas AS, Ho NI, Song Y, Raabe MJ, Xu KH, Richieri PM, Li H, Aston N, Porter RL, Patel BK, Nieman LT, Schurman N, Hudson BM, North K, Church SE, Deshpande V, Liss AS, Kim TK, Cui Y, Kim Y, Greenbaum BD, Aryee MJ, and Ting DT
- Subjects
- Humans, Cancer-Associated Fibroblasts metabolism, Interferon Regulatory Factor-3 metabolism, Extracellular Vesicles metabolism, Cell Line, Tumor, Gene Expression Regulation, Neoplastic, Signal Transduction, Myofibroblasts metabolism, Immunity, Innate, RNA metabolism, Pancreatic Neoplasms genetics, Pancreatic Neoplasms pathology, Pancreatic Neoplasms metabolism, Carcinoma, Pancreatic Ductal genetics, Carcinoma, Pancreatic Ductal pathology, Carcinoma, Pancreatic Ductal metabolism, Cell Plasticity, Tumor Microenvironment
- Abstract
Aberrant expression of repeat RNAs in pancreatic ductal adenocarcinoma (PDAC) mimics viral-like responses with implications on tumor cell state and the response of the surrounding microenvironment. To better understand the relationship of repeat RNAs in human PDAC, we performed spatial molecular imaging at single-cell resolution in 46 primary tumors, revealing correlations of high repeat RNA expression with alterations in epithelial state in PDAC cells and myofibroblast phenotype in cancer-associated fibroblasts (CAFs). This loss of cellular identity is observed with dosing of extracellular vesicles (EVs) and individual repeat RNAs of PDAC and CAF cell culture models pointing to cell-cell intercommunication of these viral-like elements. Differences in PDAC and CAF responses are driven by distinct innate immune signaling through interferon regulatory factor 3 (IRF3). The cell-context-specific viral-like responses to repeat RNAs provide a mechanism for modulation of cellular plasticity in diverse cell types in the PDAC microenvironment., Competing Interests: Declaration of interests D.T.T. and B.D.G. are co-founders with equity and consulting fees from ROME Therapeutics, a company developing drugs targeting repetitive elements, but this work was not supported by ROME Therapeutics. D.T.T. received in kind research support and a speaking honorarium from NanoString Technologies, and in kind research support from ACD-Biotechne, which was used in this work. M.J.A. is a co-founder of, owns equity in, and receives consulting fees from SeQure Dx, unrelated to this work. M.J.A. receives consulting fees from Chroma Medicine, unrelated to this work. P.D., N.S., B.M.H., K.N., S.E.C., T.K.K., Y.C., and Y.K. are or were employees of NanoString Technologies. D.T.T. has received consulting fees from PanTher Therapeutics, AstraZeneca, Sonata Therapeutics, Moderna, abrdn, Astellas, and Leica Biosystems Imaging; is a founder and has equity in PanTher Therapeutics and TellBio, Inc.; and is on the scientific advisory board with equity for ImproveBio, Inc., which are not related to this work. D.T.T. receives research support from Sanofi, AVA LifeScience GmbH, and Incyte, which was not used in this work. B.D.G. is a consultant or received honoraria for Darwin Health, Merck, PMV Pharma, Merck, Bristol-Meyers Squibb, and Chugai Pharmaceuticals and has research funding from Bristol-Meyers Squibb., (Copyright © 2024 Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
4. CAR memory-like NK cells targeting the membrane proximal domain of mesothelin demonstrate promising activity in ovarian cancer.
- Author
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Tarannum M, Dinh K, Vergara J, Birch G, Abdulhamid YZ, Kaplan IE, Ay O, Maia A, Beaver O, Sheffer M, Shapiro R, Ali AK, Dong H, Ham JD, Bobilev E, James S, Cameron AB, Nguyen QD, Ganapathy S, Chayawatto C, Koreth J, Paweletz CP, Gokhale PC, Barbie DA, Matulonis UA, Soiffer RJ, Ritz J, Porter RL, Chen J, and Romee R
- Subjects
- Animals, Female, Humans, Mice, Carcinoma, Ovarian Epithelial metabolism, Carcinoma, Ovarian Epithelial pathology, Carcinoma, Ovarian Epithelial immunology, Carcinoma, Ovarian Epithelial therapy, Cell Line, Tumor, GPI-Linked Proteins metabolism, GPI-Linked Proteins genetics, Immunologic Memory, Immunotherapy, Adoptive methods, Protein Domains, Receptors, Chimeric Antigen metabolism, Receptors, Chimeric Antigen immunology, Receptors, Chimeric Antigen genetics, Xenograft Model Antitumor Assays, Killer Cells, Natural immunology, Killer Cells, Natural metabolism, Mesothelin, Ovarian Neoplasms metabolism, Ovarian Neoplasms pathology, Ovarian Neoplasms immunology, Ovarian Neoplasms therapy
- Abstract
Epithelial ovarian cancer (EOC) remains one of the most lethal gynecological cancers. Cytokine-induced memory-like (CIML) natural killer (NK) cells have shown promising results in preclinical and early-phase clinical trials. In the current study, CIML NK cells demonstrated superior antitumor responses against a panel of EOC cell lines, increased expression of activation receptors, and up-regulation of genes involved in cell cycle/proliferation and down-regulation of inhibitory/suppressive genes. CIML NK cells transduced with a chimeric antigen receptor (CAR) targeting the membrane-proximal domain of mesothelin (MSLN) further improved the antitumor responses against MSLN-expressing EOC cells and patient-derived xenograft tumor cells. CAR arming of the CIML NK cells subtanstially reduced their dysfunction in patient-derived ascites fluid with transcriptomic changes related to altered metabolism and tonic signaling as potential mechanisms. Lastly, the adoptive transfer of MSLN-CAR CIML NK cells demonstrated remarkable inhibition of tumor growth and prevented metastatic spread in xenograft mice, supporting their potential as an effective therapeutic strategy in EOC.
- Published
- 2024
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5. Mirvetuximab soravtansine for platinum-resistant epithelial ovarian cancer.
- Author
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Porter RL and Matulonis UA
- Subjects
- Humans, Female, Carcinoma, Ovarian Epithelial drug therapy, Drug Resistance, Neoplasm, Neoplasm Recurrence, Local drug therapy, Ovarian Neoplasms drug therapy, Immunoconjugates adverse effects, Antineoplastic Agents pharmacology
- Abstract
Introduction: Mirvetuximab soravtansine (mirvetuximab) is an antibody drug conjugate (ADC) comprised of a humanized folate receptor alpha (FRα)-binding monoclonal antibody attached via a cleavable linker to the cytotoxic maytansinoid molecule, DM4. FRα is expressed in several epithelial cancers, including high grade serous ovarian cancer (HGSOC). Mirvetuximab received accelerated approval by the United States Food and Drug Administration (FDA) in November 2022 based on the results of the SORAYA trial, which tested mirvetuximab for the treatment of patients with recurrent platinum resistant HGSOC with high FRα expression and showed an overall response rate (ORR) of 32.4% and a median duration of response of 6.9 months. Mirvetuximab toxicities included low grade ocular and gastrointestinal toxicities. The National Comprehensive Cancer Network (NCCN) ovarian cancer 2023 guidelines adopted mirvetuximab as 2A, and mirvetuximab combined with bevacizumab as 2B, recommendations., Areas Covered: This manuscript will review the preclinical and clinical development of mirvetuximab, the toxicities associated with mirvetuximab and mitigation strategies, and future applications of mirvetuximab., Expert Opinion: Mirvetuximab represents the first biomarker-directed therapy with an indication specifically for the treatment of PROC. The efficacy and favorable safety profile support further development of mirvetuximab and mirvetuximab combinations in platinum sensitive and newly diagnosed ovarian cancer.
- Published
- 2023
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6. Satellite repeat RNA expression in epithelial ovarian cancer associates with a tumor-immunosuppressive phenotype.
- Author
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Porter RL, Sun S, Flores MN, Berzolla E, You E, Phillips IE, Kc N, Desai N, Tai EC, Szabolcs A, Lang ER, Pankaj A, Raabe MJ, Thapar V, Xu KH, Nieman LT, Rabe DC, Kolin DL, Stover EH, Pepin D, Stott SL, Deshpande V, Liu JF, Solovyov A, Matulonis UA, Greenbaum BD, and Ting DT
- Subjects
- Carcinoma, Ovarian Epithelial genetics, Cell Line, Tumor, Epithelial-Mesenchymal Transition genetics, Female, Gene Expression Regulation, Neoplastic, Humans, Phenotype, RNA, Tumor Microenvironment genetics, Ovarian Neoplasms genetics, RNA, Satellite
- Abstract
Aberrant expression of viral-like repeat elements is a common feature of epithelial cancers, and the substantial diversity of repeat species provides a distinct view of the cancer transcriptome. Repeatome profiling across ovarian, pancreatic, and colorectal cell lines identifies distinct clustering independent of tissue origin that is seen with coding gene analysis. Deeper analysis of ovarian cancer cell lines demonstrated that human satellite II (HSATII) satellite repeat expression was highly associated with epithelial-mesenchymal transition (EMT) and anticorrelated with IFN-response genes indicative of a more aggressive phenotype. SATII expression - and its correlation with EMT and anticorrelation with IFN-response genes - was also found in ovarian cancer RNA-Seq data and was associated with significantly shorter survival in a second independent cohort of patients with ovarian cancer. Repeat RNAs were enriched in tumor-derived extracellular vesicles capable of stimulating monocyte-derived macrophages, demonstrating a mechanism that alters the tumor microenvironment with these viral-like sequences. Targeting of HSATII with antisense locked nucleic acids stimulated IFN response and induced MHC I expression in ovarian cancer cell lines, highlighting a potential strategy of modulating the repeatome to reestablish antitumor cell immune surveillance.
- Published
- 2022
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7. Checkpoint Blockade: Not Yet NINJA Status in Ovarian Cancer.
- Author
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Porter RL and Matulonis UA
- Subjects
- Carcinoma, Ovarian Epithelial drug therapy, Carcinoma, Ovarian Epithelial genetics, Humans, Ovarian Neoplasms drug therapy
- Abstract
Competing Interests: Ursula A. MatulonisHonoraria: AdvaxisConsulting or Advisory Role: Merck, Novartis, NextCureResearch Funding: Merck, Novartis, Tesaro, Syndax, Immunogen, Mersana, Leap Therapeutics, Fujifilm, SQZ BiotechTravel, Accommodations, Expenses: AstraZenecaNo other potential conflicts of interest were reported.
- Published
- 2021
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8. Clinical Pan-Cancer Assessment of Mismatch Repair Deficiency Using Tumor-Only, Targeted Next-Generation Sequencing.
- Author
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Albayrak A, Garrido-Castro AC, Giannakis M, Umeton R, Manam MD, Stover EH, Porter RL, Johnson BE, Liaw KL, Amonkar M, Church AJ, Janeway KA, Nowak JA, Sholl L, Lin NU, and Johnson JM
- Abstract
Purpose: Given regulatory approval of immune checkpoint inhibitors in patients with mismatch repair-deficient (MMR-D) cancers agnostic to tumor type, it has become important to characterize occurrence of MMR-D and develop cost-effective screening approaches. Using a next-generation sequencing (NGS) panel (OncoPanel), we developed an algorithm to identify MMR-D frequency in tumor samples and applied it in a clinical setting with pathologist review., Methods: To predict MMR-D, we adapted methods described previously for use in NGS panels, which assess patterns of single base-pair insertion or deletion events occurring in homopolymer regions. Tumors assayed with OncoPanel between July 2013 and July 2018 were included. For tumors tested after June 2017, sequencing results were presented to pathologists in real time for clinical MMR determination, in the context of tumor mutation burden, other mutational signatures, and clinical data., Results: Of 20,301 tumors sequenced, 2.7% (553) were retrospectively classified as MMR-D by the algorithm. Of 4,404 samples with pathologist sign-out of MMR status, the algorithm classified 147 (3.3%) as MMR-D: in 116 cases, MMR-D was confirmed by a pathologist, five cases were overruled by the pathologist, and 26 were assessed as indeterminate. Overall, the highest frequencies of OncoPanel-inferred MMR-D were in endometrial (21%; 152/723), colorectal (9.7%; 169/1,744), and small bowel (9.3%; 9/97) cancers. When algorithm predictions were compared with historical MMR immunohistochemistry or polymerase chain reaction results in a set of 325 tumors sequenced before initiation of pathologist assessment, the overall sensitivity and specificity of the algorithm were 91.1% and 98.2%, respectively., Conclusion: We show that targeted, tumor-only NGS can be leveraged to determine MMR signatures across tumor types, suggesting that broader biomarker screening approaches may have clinical value.
- Published
- 2020
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9. Epithelial to mesenchymal plasticity and differential response to therapies in pancreatic ductal adenocarcinoma.
- Author
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Porter RL, Magnus NKC, Thapar V, Morris R, Szabolcs A, Neyaz A, Kulkarni AS, Tai E, Chougule A, Hillis A, Golczer G, Guo H, Yamada T, Kurokawa T, Yashaswini C, Ligorio M, Vo KD, Nieman L, Liss AS, Deshpande V, Lawrence MS, Maheswaran S, Fernandez-Del Castillo C, Hong TS, Ryan DP, O'Dwyer PJ, Drebin JA, Ferrone CR, Haber DA, and Ting DT
- Abstract
Transcriptional profiling has defined pancreatic ductal adenocarcinoma (PDAC) into distinct subtypes with the majority being classical epithelial (E) or quasi-mesenchymal (QM). Despite clear differences in clinical behavior, growing evidence indicates these subtypes exist on a continuum with features of both subtypes present and suggestive of interconverting cell states. Here, we investigated the impact of different therapies being evaluated in PDAC on the phenotypic spectrum of the E/QM state. We demonstrate using RNA-sequencing and RNA-in situ hybridization (RNA-ISH) that FOLFIRINOX combination chemotherapy induces a common shift of both E and QM PDAC toward a more QM state in cell lines and patient tumors. In contrast, Vitamin D, another drug under clinical investigation in PDAC, induces distinct transcriptional responses in each PDAC subtype, with augmentation of the baseline E and QM state. Importantly, this translates to functional changes that increase metastatic propensity in QM PDAC, but decrease dissemination in E PDAC in vivo models. These data exemplify the importance of both the initial E/QM subtype and the plasticity of E/QM states in PDAC in influencing response to therapy, which highlights their relevance in guiding clinical trials.
- Published
- 2019
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10. Clinicopathologic Features of NSCLC Diagnosed During Pregnancy or the Peripartum Period in the Era of Molecular Genotyping.
- Author
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Dagogo-Jack I, Gainor JF, Porter RL, Schultz KR, Solomon BJ, Stevens S, Azzoli CG, Sequist LV, Lennes IT, and Shaw AT
- Subjects
- Adult, Anaplastic Lymphoma Kinase, Carcinoma, Non-Small-Cell Lung enzymology, Carcinoma, Non-Small-Cell Lung genetics, Carcinoma, Non-Small-Cell Lung mortality, ErbB Receptors genetics, Female, Gene Rearrangement, Genotype, Humans, Lung Neoplasms enzymology, Lung Neoplasms genetics, Lung Neoplasms mortality, Peripartum Period, Pregnancy, Pregnancy Complications, Neoplastic enzymology, Pregnancy Complications, Neoplastic genetics, Pregnancy Complications, Neoplastic mortality, Puerperal Disorders enzymology, Puerperal Disorders genetics, Puerperal Disorders mortality, Receptor Protein-Tyrosine Kinases genetics, Retrospective Studies, Carcinoma, Non-Small-Cell Lung pathology, Lung Neoplasms pathology, Pregnancy Complications, Neoplastic pathology, Puerperal Disorders pathology
- Abstract
Introduction: Cancer will be diagnosed in one in 1000 women during pregnancy. The outcomes of NSCLC diagnosed during pregnancy are dismal, with most patients dying within 1 year. Actionable mutations are more likely to be found among younger patients with NSCLC. However, most previous reports of NSCLC diagnosed during pregnancy did not include molecular genotyping., Methods: We performed a retrospective analysis of patients seen at our institution between 2009 and 2015 to identify women in whom NSCLC was diagnosed during pregnancy or the peripartum period and determined clinicopathologic features, including molecular genotype., Results: We identified 2422 women with NSCLC, including 160 women of reproductive age. Among the women of reproductive age, eight cases of NSCLC diagnosed during pregnancy or the peripartum period were identified; all were diagnosed in minimal or never-smokers with metastatic adenocarcinoma. Six of these patients were found to have anaplastic lymphoma kinase gene (ALK) rearrangements, whereas the remaining two were EGFR mutation positive. We observed a borderline significant association between a diagnosis of NSCLC during pregnancy or the peripartum period and ALK positivity (p = 0.053). All eight women in whom NSCLC was diagnosed during pregnancy or the peripartum period received treatment with genotype-directed therapies after delivery. The median overall survival has not been reached at a median follow-up of 30 months., Conclusions: Although a diagnosis of NSCLC during pregnancy or the peripartum period is rare, diagnostic evaluation should not be delayed in pregnant women presenting with symptoms worrisome for lung cancer. Evaluation should include testing for targetable molecular alterations., (Copyright © 2016 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)
- Published
- 2016
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11. Prostaglandin E2 increases hematopoietic stem cell survival and accelerates hematopoietic recovery after radiation injury.
- Author
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Porter RL, Georger MA, Bromberg O, McGrath KE, Frisch BJ, Becker MW, and Calvi LM
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- Actins genetics, Actins immunology, Animals, Apoptosis drug effects, Apoptosis radiation effects, Bone Marrow Cells pathology, Bone Marrow Cells radiation effects, Cell Differentiation drug effects, Cell Differentiation radiation effects, Cell Proliferation drug effects, Cell Proliferation radiation effects, Cell Survival drug effects, Cell Survival radiation effects, Cellular Microenvironment drug effects, Cellular Microenvironment radiation effects, Cyclooxygenase 2 genetics, Cyclooxygenase 2 immunology, Dinoprostone analogs & derivatives, Gene Expression drug effects, Gene Expression radiation effects, Hematopoietic Stem Cells pathology, Hematopoietic Stem Cells radiation effects, Macrophages pathology, Macrophages radiation effects, Male, Mice, Mice, Transgenic, Radiation Injuries, Experimental immunology, Radiation Injuries, Experimental pathology, Whole-Body Irradiation, Bone Marrow Cells drug effects, Dinoprostone pharmacology, Hematopoietic Stem Cells drug effects, Macrophages drug effects, Radiation Injuries, Experimental drug therapy, Radiation-Protective Agents pharmacology
- Abstract
Hematopoietic stem and progenitor cells (HSPCs), which continuously maintain all mature blood cells, are regulated within the marrow microenvironment. We previously reported that pharmacologic treatment of naïve mice with prostaglandin E2 (PGE2) expands HSPCs. However, the cellular mechanisms mediating this expansion remain unknown. Here, we demonstrate that PGE2 treatment in naïve mice inhibits apoptosis of HSPCs without changing their proliferation rate. In a murine model of sublethal total body irradiation (TBI), in which HSPCs are rapidly lost, treatment with a long-acting PGE2 analog (dmPGE2) reversed the apoptotic program initiated by TBI. dmPGE2 treatment in vivo decreased the loss of functional HSPCs following radiation injury, as demonstrated both phenotypically and by their increased reconstitution capacity. The antiapoptotic effect of dmPGE2 on HSPCs did not impair their ability to differentiate in vivo, resulting instead in improved hematopoietic recovery after TBI. dmPGE2 also increased microenvironmental cyclooxygenase-2 expression and expanded the α-smooth muscle actin-expressing subset of marrow macrophages, thus enhancing the bone marrow microenvironmental response to TBI. Therefore, in vivo treatment with PGE2 analogs may be particularly beneficial to HSPCs in the setting of injury by targeting them both directly and also through their niche. The current data provide rationale for in vivo manipulation of the HSPC pool as a strategy to improve recovery after myelosuppression., (Copyright © 2012 AlphaMed Press.)
- Published
- 2013
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12. Osteoblastic N-cadherin is not required for microenvironmental support and regulation of hematopoietic stem and progenitor cells.
- Author
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Bromberg O, Frisch BJ, Weber JM, Porter RL, Civitelli R, and Calvi LM
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- Aging genetics, Aging pathology, Animals, Base Sequence, Bone Density drug effects, Bone Density genetics, Bone Density physiology, Bone Remodeling drug effects, Bone Remodeling genetics, Bone Remodeling physiology, Bone and Bones anatomy & histology, Bone and Bones drug effects, Bone and Bones physiology, Cadherins deficiency, Cadherins genetics, Cellular Microenvironment physiology, Hematopoiesis drug effects, Hematopoiesis genetics, Hematopoiesis physiology, Hematopoietic Stem Cells drug effects, Male, Mice, Mice, 129 Strain, Mice, Inbred C57BL, Mice, Transgenic, Osteoblasts drug effects, Parathyroid Hormone pharmacology, RNA, Messenger genetics, RNA, Messenger metabolism, Cadherins physiology, Hematopoietic Stem Cells cytology, Hematopoietic Stem Cells physiology, Osteoblasts cytology, Osteoblasts physiology
- Abstract
Hematopoietic stem cell (HSC) regulation is highly dependent on interactions with the marrow microenvironment. Controversy exists on N-cadherin's role in support of HSCs. Specifically, it is unknown whether microenvironmental N-cadherin is required for normal marrow microarchitecture and for hematopoiesis. To determine whether osteoblastic N-cadherin is required for HSC regulation, we used a genetic murine model in which deletion of Cdh2, the gene encoding N-cadherin, has been targeted to cells of the osteoblastic lineage. Targeted deletion of N-cadherin resulted in an age-dependent bone phenotype, ultimately characterized by decreased mineralized bone, but no difference in steady-state HSC numbers or function at any time tested, and normal recovery from myeloablative injury. Intermittent parathyroid hormone (PTH) treatment is well established as anabolic to bone and to increase marrow HSCs through microenvironmental interactions. Lack of osteoblastic N-cadherin did not block the bone anabolic or the HSC effects of PTH treatment. This report demonstrates that osteoblastic N-cadherin is not required for regulation of steady-state hematopoiesis, HSC response to myeloablation, or for rapid expansion of HSCs through intermittent treatment with PTH.
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- 2012
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13. Clr4/Suv39 and RNA quality control factors cooperate to trigger RNAi and suppress antisense RNA.
- Author
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Zhang K, Fischer T, Porter RL, Dhakshnamoorthy J, Zofall M, Zhou M, Veenstra T, and Grewal SI
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- Cell Cycle Proteins genetics, Centromere metabolism, Euchromatin metabolism, Histone-Lysine N-Methyltransferase, Histones metabolism, Methylation, Methyltransferases genetics, Mutation, RNA Processing, Post-Transcriptional, RNA-Binding Proteins metabolism, Saccharomyces cerevisiae Proteins metabolism, Schizosaccharomyces pombe Proteins genetics, Cell Cycle Proteins metabolism, Methyltransferases metabolism, RNA Interference, RNA, Antisense metabolism, RNA, Fungal metabolism, Schizosaccharomyces genetics, Schizosaccharomyces metabolism, Schizosaccharomyces pombe Proteins metabolism
- Abstract
Pervasive transcription of eukaryotic genomes generates a plethora of noncoding RNAs. In fission yeast, the heterochromatin factor Clr4/Suv39 methyltransferase facilitates RNA interference (RNAi)-mediated processing of centromeric transcripts into small interfering RNAs (siRNAs). Clr4 also mediates degradation of antisense RNAs at euchromatic loci, but the underlying mechanism has remained elusive. We show that Clr4 and the RNAi effector RITS (RNA-induced transcriptional silencing) interact with Mlo3, a protein related to mRNA quality control and export factors. Loss of Clr4 impairs RITS interaction with Mlo3, which is required for centromeric siRNA production and antisense suppression. Mlo3 also interacts with the RNA surveillance factor TRAMP, which suppresses antisense RNAs targeted by Clr4 and RNAi. These findings link Clr4 to RNA quality control machinery and suggest a pathway for processing potentially deleterious RNAs through the coordinated actions of RNAi and other RNA processing activities.
- Published
- 2011
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14. X-ray diffraction evidence for myosin-troponin connections and tropomyosin movement during stretch activation of insect flight muscle.
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Perz-Edwards RJ, Irving TC, Baumann BA, Gore D, Hutchinson DC, Kržič U, Porter RL, Ward AB, and Reedy MK
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- Actins metabolism, Actins ultrastructure, Animals, Biomechanical Phenomena, Calcium metabolism, Heteroptera physiology, Muscles physiology, Muscles ultrastructure, Tropomyosin metabolism, Tropomyosin ultrastructure, X-Ray Diffraction, Actins chemistry, Flight, Animal physiology, Heteroptera chemistry, Models, Biological, Models, Molecular, Muscles chemistry, Signal Transduction physiology, Tropomyosin chemistry
- Abstract
Stretch activation is important in the mechanical properties of vertebrate cardiac muscle and essential to the flight muscles of most insects. Despite decades of investigation, the underlying molecular mechanism of stretch activation is unknown. We investigated the role of recently observed connections between myosin and troponin, called "troponin bridges," by analyzing real-time X-ray diffraction "movies" from sinusoidally stretch-activated Lethocerus muscles. Observed changes in X-ray reflections arising from myosin heads, actin filaments, troponin, and tropomyosin were consistent with the hypothesis that troponin bridges are the key agent of mechanical signal transduction. The time-resolved sequence of molecular changes suggests a mechanism for stretch activation, in which troponin bridges mechanically tug tropomyosin aside to relieve tropomyosin's steric blocking of myosin-actin binding. This enables subsequent force production, with cross-bridge targeting further enhanced by stretch-induced lattice compression and thick-filament twisting. Similar linkages may operate in other muscle systems, such as mammalian cardiac muscle, where stretch activation is thought to aid in cardiac ejection.
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- 2011
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15. In vivo prostaglandin E2 treatment alters the bone marrow microenvironment and preferentially expands short-term hematopoietic stem cells.
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Frisch BJ, Porter RL, Gigliotti BJ, Olm-Shipman AJ, Weber JM, O'Keefe RJ, Jordan CT, and Calvi LM
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- Animals, Bone and Bones anatomy & histology, Bone and Bones drug effects, Cell Differentiation drug effects, Colony-Forming Units Assay, Graft Survival drug effects, Hematopoiesis drug effects, Hematopoietic Stem Cell Transplantation, Male, Mice, Mice, Inbred C57BL, Osteoblasts cytology, Osteoblasts drug effects, Osteoclasts cytology, Osteoclasts drug effects, Dinoprostone pharmacology, Hematopoietic Stem Cells cytology, Hematopoietic Stem Cells drug effects
- Abstract
Microenvironmental signals can determine hematopoietic stem cell (HSC) fate choices both directly and through stimulation of niche cells. In the bone marrow, prostaglandin E(2) (PGE(2)) is known to affect both osteoblasts and osteoclasts, whereas in vitro it expands HSCs and affects differentiation of hematopoietic progenitors. We hypothesized that in vivo PGE(2) treatment could expand HSCs through effects on both HSCs and their microenvironment. PGE(2)-treated mice had significantly decreased number of bone trabeculae, suggesting disruption of their microarchitecture. In addition, in vivo PGE(2) increased lineage(-) Sca-1(+) c-kit(+) bone marrow cells without inhibiting their differentiation. However, detailed immunophenotyping demonstrated a PGE(2)-dependent increase in short-term HSCs/multipotent progenitors (ST-HSCs/MPPs) only. Bone marrow cells transplanted from PGE(2) versus vehicle-treated donors had superior lymphomyeloid reconstitution, which ceased by 16 weeks, also suggesting that ST-HSCs were preferentially expanded. This was confirmed by serial transplantation studies. Thus in vivo PGE(2) treatment, probably through a combination of direct and microenvironmental actions, preferentially expands ST-HSCs in the absence of marrow injury, with no negative impact on hematopoietic progenitors or long-term HSCs. These novel effects of PGE(2) could be exploited clinically to increase donor ST-HSCs, which are highly proliferative and could accelerate hematopoietic recovery after stem cell transplantation.
- Published
- 2009
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16. Key endothelial signals required for hematopoietic recovery.
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Porter RL and Calvi LM
- Subjects
- Animals, Mice, Bone Marrow blood supply, Endothelium, Vascular physiology, Hematopoiesis physiology, Hematopoietic Stem Cells physiology, Vascular Endothelial Growth Factor Receptor-2 physiology
- Abstract
In this issue of Cell Stem Cell, Hooper et al. (2009) use a combination of immunohistochemistry and flow cytometry to characterize the bone marrow vasculature both before and after injury. The authors demonstrate that recovery of normal hematopoiesis after myelosuppressive insult is dependent upon endothelial VEGFR2.
- Published
- 2009
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17. Hematopoietic niche and bone meet.
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Frisch BJ, Porter RL, and Calvi LM
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- Adipocytes metabolism, Adipocytes pathology, Bone Marrow metabolism, Bone Neoplasms metabolism, Bone Neoplasms pathology, Bone Neoplasms secondary, Cell Transformation, Neoplastic metabolism, Hematologic Neoplasms metabolism, Hematologic Neoplasms pathology, Hematopoietic Stem Cells metabolism, Humans, Neurons metabolism, Neurons pathology, Osteoblasts metabolism, Osteoblasts pathology, Osteoclasts metabolism, Osteoclasts pathology, Bone Marrow pathology, Cell Transformation, Neoplastic pathology, Hematopoietic Stem Cells pathology
- Abstract
Purpose of Review: To provide an overview of the hematopoietic stem cell (HSC) niche in the bone marrow. In addition to highlighting recent advances in the field, we will also discuss components of the niche that may contribute to the development of cancer, or cancer metastases to the bone., Recent Findings: Much progress has been very recently made in the understanding of the cellular and molecular interactions in the HSC microenvironment. These recent findings point out the extraordinary complexity of the HSC microenvironment. Emerging data also suggest convergence of signals important for HSC and for leukemia or metastatic disease support., Summary: The HSC niche comprises complex interactions between multiple cell types and molecules requiring cell-cell signaling as well as local secretion. These components can be thought of as therapeutic targets not only for HSC expansion, but also to modify behavior of hematopoietic malignancies and cancer metastases to the bone.
- Published
- 2008
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18. Communications between bone cells and hematopoietic stem cells.
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Porter RL and Calvi LM
- Subjects
- Animals, Cell Lineage, Humans, Signal Transduction, Cell Communication, Hematopoietic Stem Cells physiology, Osteoblasts physiology, Osteocytes physiology
- Abstract
The skeletal system, while characterized by a hard tissue component, is in fact an extraordinarily dynamic system, with disparate functions ranging from structural support, movement and locomotion and soft-organ protection, to the maintenance of calcium homeostasis. Amongst these functions, it has long been known that mammalian bones house definitive hematopoiesis. In fact, several data demonstrate that the bone microenvironment provides essential regulatory cues to the hematopoietic system. In particular, interactions between the bone-forming cells, or osteoblasts, and the most primitive Hematopoietic Stem Cells (HSC) have recently been defined. This review will focus mainly on the role of osteoblasts as HSC regulatory cells, discussing the signaling mechanisms and molecules currently thought to be involved in their modulation of HSC behavior. We will then review additional cellular components of the HSC niche, including endothelial cells and osteoclasts. Finally, we will discuss the potential clinical implications of our emerging understanding of the complex HSC microenvironment.
- Published
- 2008
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19. Enucleation of primitive erythroid cells generates a transient population of "pyrenocytes" in the mammalian fetus.
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McGrath KE, Kingsley PD, Koniski AD, Porter RL, Bushnell TP, and Palis J
- Subjects
- Animals, DNA Fragmentation, Embryonic Development, Female, Mice, Mice, Inbred ICR, Pregnancy, Yolk Sac physiology, Erythroblasts cytology, Erythroblasts physiology, Erythropoiesis physiology, Fetus physiology
- Abstract
Enucleation is the hallmark of erythropoiesis in mammals. Previously, we determined that yolk sac-derived primitive erythroblasts mature in the bloodstream and enucleate between embryonic day (E)14.5 and E16.5 of mouse gestation. While definitive erythroblasts enucleate by nuclear extrusion, generating reticulocytes and small, nucleated cells with a thin rim of cytoplasm ("pyrenocytes"), it is unclear by what mechanism primitive erythroblasts enucleate. Immunohistochemical examination of fetal blood revealed primitive pyrenocytes that were confirmed by multispectral imaging flow cytometry to constitute a distinct, transient cell population. The frequency of primitive erythroblasts was higher in the liver than the bloodstream, suggesting that they enucleate in the liver, a possibility supported by their proximity to liver macrophages and the isolation of erythroblast islands containing primitive erythroblasts. Furthermore, primitive erythroblasts can reconstitute erythroblast islands in vitro by attaching to fetal liver-derived macrophages, an association mediated in part by alpha4 integrin. Late-stage primitive erythroblasts fail to enucleate in vitro unless cocultured with macrophage cells. Our studies indicate that primitive erythroblasts enucleate by nuclear extrusion to generate erythrocytes and pyrenocytes and suggest this occurs in the fetal liver in association with macrophages. Continued studies comparing primitive and definitive erythropoiesis will lead to an improved understanding of terminal erythroid maturation.
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- 2008
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20. Is polyploidy an important genotoxic lesion?
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Mitchell ID, Lambert TR, Burden M, Sunderland J, Porter RL, and Carlton JB
- Subjects
- Chromosome Aberrations genetics, Humans, Karyotyping, Mutagenicity Tests, Prevalence, Genes drug effects, Lymphocytes drug effects, Lymphocytes physiology, Polyploidy
- Abstract
The importance of polyploidy as a genotoxic lesion is uncertain and there have been few publications and no reviews which have included data on spontaneous or induced polyploidy in routine genotoxicity screening. We have attempted to clarify some of the issues by reviewing the published literature and by reference to our historical data base for metaphase analysis of cultured human lymphocytes. In our studies on pharmaceutical compounds polyploidy was the lesion most often found, being induced by approximately 40% of the compounds tested. The mean spontaneous frequency was between 0.1 and 0.3%, and values for polyploidy induction were 5-fold to > 100-fold the spontaneous value. Spontaneous polyploids tended to be near-exact multiples of the haploid chromosome number whereas induced 'polyploids' were, in fact, very heteroploid with a wide range of chromosome numbers. Polyploidy induction often occurred at non-toxic concentrations, usually there were well defined no-effect (threshold) levels and it was unrelated to other genetic effects. Such observations would be expected for inducers of polyploidy because the target molecules are not DNA and for these non-DNA targets there is usually a degree of redundancy. Therefore, inducers of polyploidy are only likely to be a hazard for humans if they are positive at or below therapeutic concentrations. We conclude that polyploidy/near-polyploidy (shown as 'polyploidy' throughout) should be scored as accessory data which becomes important only when induction occurs at therapeutic levels.
- Published
- 1995
- Full Text
- View/download PDF
21. The purification of urease from Aspergillus nidulans.
- Author
-
Creaser EH and Porter RL
- Subjects
- Ammonium Sulfate pharmacology, Chromatography, Affinity, Chromatography, Gel, Aspergillus nidulans enzymology, Urease isolation & purification
- Abstract
A purification procedure is described for Aspergillus urease, the most important step being affinity chromatography on hydroxyurea Sepharose. The enzyme exists as a single active species of Mr 240,000. The pure enzyme has an activity of 670 mumol urea hydrolysed/min, has a Km of 10(-3) M, an optimum pH of 8.5 and a sub-unit Mr of 40,000.
- Published
- 1985
- Full Text
- View/download PDF
22. Management and time utilization.
- Author
-
Porter RL
- Subjects
- Time Factors, United States, Efficiency, Health Facility Administrators, Mental Health Services organization & administration
- Published
- 1983
- Full Text
- View/download PDF
23. Purification and preliminary characterization of alcohol dehydrogenase from Aspergillus nidulans.
- Author
-
Creaser EH, Porter RL, Britt KA, Pateman JA, and Doy CH
- Subjects
- Alcohol Dehydrogenase, Alcohol Oxidoreductases biosynthesis, Alcohol Oxidoreductases isolation & purification, Amino Acids analysis, Chemical Phenomena, Chemistry, Electrophoresis, Polyacrylamide Gel, Enzyme Induction drug effects, Kinetics, Substrate Specificity, Alcohol Oxidoreductases metabolism, Aspergillus nidulans enzymology
- Abstract
Aspergillus alcohol dehydrogenase is produced in response to growth in the presence of a wide variety of inducers, of which the most effective are short-chain alcohols and ketones, e.g. butan-2-one and propan-2-ol. The enzyme can be readily extracted from fresh or freeze-dried cells and purified to homogeneity on Blue Sepharose in a single step by using specific elution with NAD+ and pyrazole. The pure enzyme has Mr 290 000 by electrophoresis or gel filtration; it is a homopolymer with subunit Mr 37 500 by electrophoresis in sodium dodecyl sulphate; its amino acid composition corresponds to Mr 37 900, and the native enzyme contains one zinc atom per subunit. The enzyme is NAD-specific and has a wide substrate activity in the forward and reverse reactions; its activity profile is not identical with those of other alcohol dehydrogenases.
- Published
- 1985
- Full Text
- View/download PDF
24. Department of the Interior, Census Office.
- Author
-
Porter RL
- Published
- 1889
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