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Masjkur J, Poser SW, Nikolakopoulou P, Chrousos G, McKay RD, Bornstein SR, Jones PM, Androutsellis-Theotokis A. Endocrine Pancreas Development and Regeneration: Noncanonical Ideas From Neural Stem Cell Biology. Diabetes 2016; 65:314-30. [PMID: 26798118 DOI: 10.2337/db15-1099] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Loss of insulin-producing pancreatic islet β-cells is a hallmark of type 1 diabetes. Several experimental paradigms demonstrate that these cells can, in principle, be regenerated from multiple endogenous sources using signaling pathways that are also used during pancreas development. A thorough understanding of these pathways will provide improved opportunities for therapeutic intervention. It is now appreciated that signaling pathways should not be seen as "on" or "off" but that the degree of activity may result in wildly different cellular outcomes. In addition to the degree of operation of a signaling pathway, noncanonical branches also play important roles. Thus, a pathway, once considered as "off" or "low" may actually be highly operational but may be using noncanonical branches. Such branches are only now revealing themselves as new tools to assay them are being generated. A formidable source of noncanonical signal transduction concepts is neural stem cells because these cells appear to have acquired unusual signaling interpretations to allow them to maintain their unique dual properties (self-renewal and multipotency). We discuss how such findings from the neural field can provide a blueprint for the identification of new molecular mechanisms regulating pancreatic biology, with a focus on Notch, Hes/Hey, and hedgehog pathways.
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Affiliation(s)
- Jimmy Masjkur
- Department of Internal Medicine III, Technische Universität Dresden, Dresden, Germany
| | - Steven W Poser
- Department of Internal Medicine III, Technische Universität Dresden, Dresden, Germany
| | | | - George Chrousos
- First Department of Pediatrics, University of Athens Medical School and Aghia Sophia Children's Hospital, Athens, Greece
| | | | - Stefan R Bornstein
- Department of Internal Medicine III, Technische Universität Dresden, Dresden, Germany
| | - Peter M Jones
- Diabetes Research Group, Division of Diabetes & Nutritional Sciences, King's College London, London, U.K
| | - Andreas Androutsellis-Theotokis
- Department of Internal Medicine III, Technische Universität Dresden, Dresden, Germany Center for Regenerative Therapies Dresden, Dresden, Germany Department of Stem Cell Biology, Centre for Biomolecular Sciences, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, U.K.
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Lee SH, Athavankar S, Cohen T, Piran R, Kiselyuk A, Levine F. Identification of alverine and benfluorex as HNF4α activators. ACS Chem Biol 2013; 8:1730-6. [PMID: 23675775 DOI: 10.1021/cb4000986] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The principal finding of this study is that two drugs, alverine and benfluorex, used in vastly different clinical settings, activated the nuclear receptor transcription factor HNF4α. Both were hits in a high-throughput screen for compounds that reversed the inhibitory effect of the fatty acid palmitate on human insulin promoter activity. Alverine is used in the treatment of irritable bowel syndrome, while benfluorex (Mediator) was used to treat hyperlipidemia and type II diabetes. Benfluorex was withdrawn from the market recently because of serious cardiovascular side effects related to fenfluramine-like activity. Strikingly, alverine and benfluorex have a previously unrecognized structural similarity, consistent with a common mechanism of action. Gene expression and biochemical studies revealed that they both activate HNF4α. This novel mechanism of action should lead to a reinterpretation of previous studies with these drugs and suggests a path toward the development of therapies for diseases such as inflammatory bowel and diabetes that may respond to HNF4α activators.
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Affiliation(s)
- Seung-Hee Lee
- Sanford Children’s
Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla,
California, 92037, United States
| | - Sonalee Athavankar
- Sanford Children’s
Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla,
California, 92037, United States
| | - Tom Cohen
- Sanford Children’s
Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla,
California, 92037, United States
| | - Ron Piran
- Sanford Children’s
Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla,
California, 92037, United States
| | - Alice Kiselyuk
- Sanford Children’s
Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla,
California, 92037, United States
| | - Fred Levine
- Sanford Children’s
Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla,
California, 92037, United States
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Scharfmann R, Rachdi L, Ravassard P. Concise review: in search of unlimited sources of functional human pancreatic beta cells. Stem Cells Transl Med 2012; 2:61-7. [PMID: 23283495 DOI: 10.5966/sctm.2012-0120] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
It is well-established that insulin-producing pancreatic beta cells are central in diabetes. In type 1 diabetes, beta cells are destroyed by an autoimmune mechanism, whereas in type 2 diabetes, there is a decrease in functional beta-cell mass. In this context, studying beta cells is of major importance. Beta cells represent only 1% of total pancreatic cells and are found dispersed in the pancreatic gland. During the past decades, many tools and approaches have been developed to study rodent beta cells that efficiently pushed the field forward. However, rodent and human beta cells are not identical, and our knowledge of human beta cells has not progressed as quickly as our understanding of rodent beta cells. We believe that one of the reasons for this inefficient progress is the difficulty of accessing unlimited sources of functional human pancreatic beta cells. The main focus of this review concerns recent strategies to generate new sources of human pancreatic beta cells.
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Lee SH, Hao E, Levine F, Itkin-Ansari P. Id3 upregulates BrdU incorporation associated with a DNA damage response, not replication, in human pancreatic β-cells. Islets 2011; 3:358-66. [PMID: 21964314 PMCID: PMC3329516 DOI: 10.4161/isl.3.6.17923] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Elucidating mechanisms of cell cycle control in normally quiescent human pancreatic β-cells has the potential to impact regeneration strategies for diabetes. Previously we demonstrated that Id3, a repressor of basic Helix-Loop-Helix (bHLH) proteins, was sufficient to induce cell cycle entry in pancreatic duct cells, which are closely related to β-cells developmentally. We hypothesized that Id3 might similarly induce cell cycle entry in primary human β-cells. To test this directly, adult human β-cells were transduced with adenovirus expressing Id3. Consistent with a replicative response, β-cells exhibited BrdU incorporation. Further, Id3 potently repressed expression of the cyclin dependent kinase inhibitor p57 (Kip2 ) , a gene which is also silenced in a rare β-cell hyperproliferative disorder in infants. Surprisingly however, BrdU positive β-cells did not express the proliferation markers Ki67 and pHH3. Instead, BrdU uptake reflected a DNA damage response, as manifested by hydroxyurea incorporation, γH2AX expression, and 53BP1 subcellular relocalization. The uncoupling of BrdU uptake from replication raises a cautionary note about interpreting studies relying solely upon BrdU incorporation as evidence of β-cell proliferation. The data also establish that loss of p57 (Kip2) is not sufficient to induce cell cycle entry in adult β-cells. Moreover, the differential responses to Id3 between duct and β-cells reveal that β-cells possess intrinsic resistance to cell cycle entry not common to all quiescent epithelial cells in the adult human pancreas. The data provide a much needed comparative model for investigating the molecular basis for this resistance in order to develop a strategy for improving replication competence in β-cells.
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Affiliation(s)
- Seung-Hee Lee
- Sanford Children’s Health Research Center; La Jolla, CA USA
| | - Ergeng Hao
- Sanford Children’s Health Research Center; La Jolla, CA USA
- Department of Pediatrics; University of California San Diego; La Jolla, CA USA
| | - Fred Levine
- Sanford Children’s Health Research Center; La Jolla, CA USA
| | - Pamela Itkin-Ansari
- Department of Pediatrics; University of California San Diego; La Jolla, CA USA
- Development and Aging Program; Sanford-Burnham Institute for Medical Research; La Jolla, CA USA
- Correspondence to: Pamela Itkin-Ansari,
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Gao P, Jiao Y, Xiong Q, Wang CY, Gerling I, Gu W. Genetic and Molecular Basis of QTL of Diabetes in Mouse: Genes and Polymorphisms. Curr Genomics 2011; 9:324-37. [PMID: 19471607 PMCID: PMC2685644 DOI: 10.2174/138920208785133253] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 04/14/2008] [Accepted: 04/17/2008] [Indexed: 12/14/2022] Open
Abstract
A systematic study has been conducted of all available reports in PubMed and OMIM (Online Mendelian Inheritance in Man) to examine the genetic and molecular basis of quantitative genetic loci (QTL) of diabetes with the main focus on genes and polymorphisms. The major question is, What can the QTL tell us? Specifically, we want to know whether those genome regions differ from other regions in terms of genes relevant to diabetes. Which genes are within those QTL regions, and, among them, which genes have already been linked to diabetes? whether more polymorphisms have been associated with diabetes in the QTL regions than in the non-QTL regions. Our search revealed a total of 9038 genes from 26 type 1 diabetes QTL, which cover 667,096,006 bp of the mouse genomic sequence. On one hand, a large number of candidate genes are in each of these QTL; on the other hand, we found that some obvious candidate genes of QTL have not yet been investigated. Thus, the comprehensive search of candidate genes for known QTL may provide unexpected benefit for identifying QTL genes for diabetes.
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Affiliation(s)
- Peng Gao
- Departments of Orthopaedic Surgery, Campbell Clinic and Pathology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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Lightfoot YL, Chen J, Mathews CE. Role of the mitochondria in immune-mediated apoptotic death of the human pancreatic β cell line βLox5. PLoS One 2011; 6:e20617. [PMID: 21738580 PMCID: PMC3124469 DOI: 10.1371/journal.pone.0020617] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 05/07/2011] [Indexed: 11/19/2022] Open
Abstract
Mitochondria are indispensable in the life and death of many types of eukaryotic cells. In pancreatic beta cells, mitochondria play an essential role in the secretion of insulin, a hormone that regulates blood glucose levels. Unregulated blood glucose is a hallmark symptom of diabetes. The onset of Type 1 diabetes is preceded by autoimmune-mediated destruction of beta cells. However, the exact role of mitochondria has not been assessed in beta cell death. In this study, we examine the role of mitochondria in both Fas- and proinflammatory cytokine-mediated destruction of the human beta cell line, βLox5. IFNγ primed βLox5 cells for apoptosis by elevating cell surface Fas. Consequently, βLox5 cells were killed by caspase-dependent apoptosis by agonistic activation of Fas, but only after priming with IFNγ. This beta cell line undergoes both apoptotic and necrotic cell death after incubation with the combination of the proinflammatory cytokines IFNγ and TNFα. Additionally, both caspase-dependent and -independent mechanisms that require proper mitochondrial function are involved. Mitochondrial contributions to βLox5 cell death were analyzed using mitochondrial DNA (mtDNA) depleted βLox5 cells, or βLox5 ρ0 cells. βLox5 ρ0 cells are not sensitive to IFNγ and TNFα killing, indicating a direct role for the mitochondria in cytokine-induced cell death of the parental cell line. However, βLox5 ρ0 cells are susceptible to Fas killing, implicating caspase-dependent extrinsic apoptotic death is the mechanism by which these human beta cells die after Fas ligation. These data support the hypothesis that immune mediators kill βLox5 cells by both mitochondrial-dependent intrinsic and caspase-dependent extrinsic pathways.
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Affiliation(s)
- Yaíma L. Lightfoot
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America
| | - Jing Chen
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America
| | - Clayton E. Mathews
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America
- * E-mail:
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HES6-1 and HES6-2 function through different mechanisms during neuronal differentiation. PLoS One 2010; 5:e15459. [PMID: 21151987 PMCID: PMC2996300 DOI: 10.1371/journal.pone.0015459] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 10/01/2010] [Indexed: 01/19/2023] Open
Abstract
Background Notch signalling plays a central role in the mechanisms regulating neuronal differentiation in the vertebrate nervous system. The transcriptional repressors encoded by Hes genes are the main effectors of this pathway, acting in neural progenitors during the lateral inhibition process to repress proneural genes and inhibit differentiation. However, Hes6 genes seem to behave differently: they are expressed in differentiating neurons and facilitate the activity of proneural genes in promoting neurogenesis. Still, the molecular mechanisms underlying this unique function of Hes6 genes are not yet understood. Methodology/Principal Findings Here, we identify two subgroups of Hes6 genes that seem conserved in most vertebrate species and characterize a novel Hes6 gene in chicken: cHes6-1. The embryonic expression pattern of cHes6-1 suggests roles for this gene in the formation of the pancreas, nervous system and in the generation of body asymmetry. We show that cHes6-1 is negatively regulated by Notch signalling in the developing embryonic spinal cord and in pancreatic progenitors, but requires Notch for the observed asymmetric expression at the lateral mesoderm. Functional studies by ectopic expression in the chick embryonic neural tube revealed that cHES6-1 up-regulates the expression of cDelta1 and cHes5 genes, in contrast with overexpression of cHES6-2, which represses the same genes. We show that this activity of cHES6-2 is dependent on its capacity to bind DNA and repress transcription, while cHES6-1 seems to function by sequestering other HES proteins and inhibit their activity as transcriptional repressors. Conclusions/Significance Our results indicate that the two chick HES6 proteins act at different phases of neuronal differentiation, contributing to the progression of neurogenesis by different mechanisms: while cHES6-2 represses the transcription of Hes genes, cHES6-1 acts later, sequestering HES proteins. Together, the two cHES6 proteins progressively shut down the Notch-mediated progenitor program and ensure that neuronal differentiation can proceed.
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Kiselyuk A, Farber-Katz S, Cohen T, Lee SH, Geron I, Azimi B, Heynen-Genel S, Singer O, Price J, Mercola M, Itkin-Ansari P, Levine F. Phenothiazine neuroleptics signal to the human insulin promoter as revealed by a novel high-throughput screen. ACTA ACUST UNITED AC 2010; 15:663-70. [PMID: 20547533 DOI: 10.1177/1087057110372257] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A number of diabetogenic stimuli interact to influence insulin promoter activity, making it an attractive target for both mechanistic studies and therapeutic interventions. High-throughput screening (HTS) for insulin promoter modulators has the potential to reveal novel inputs into the control of that central element of the pancreatic beta-cell. A cell line from human islets in which the expression of insulin and other beta-cell-restricted genes are modulated by an inducible form of the bHLH transcription factor E47 was developed. This cell line, T6PNE, was adapted for HTS by transduction with a vector expressing green fluorescent protein under the control of the human insulin promoter. The resulting cell line was screened against a library of known drugs for those that increase insulin promoter activity. Members of the phenothiazine class of neuroleptics increased insulin gene expression upon short-term exposure. Chronic treatment, however, resulted in suppression of insulin promoter activity, consistent with the effect of phenothiazines observed clinically to induce diabetes in chronically treated patients. In addition to providing insights into previously unrecognized targets and mechanisms of action of phenothiazines, the novel cell line described here provides a broadly applicable platform for mining new molecular drug targets and central regulators of beta-cell differentiated function.
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Affiliation(s)
- Alice Kiselyuk
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
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