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Safonova TN, Zaitseva GV. [Cell technologies as a basis for the development of regenerative principles for the treatment of lacrimal gland diseases]. Vestn Oftalmol 2024; 140:158-165. [PMID: 38739146 DOI: 10.17116/oftalma2024140022158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
The lacrimal gland (LG) is a tubuloacinar exocrine gland composed of acinar, ductal, and myoepithelial cells. Three-dimensional distribution of acinar lobules, ducts, and myoepithelial cells is necessary for the effective functioning of the organ. LG is the main organ of immune surveillance of the ocular surface system. The embryogenesis of the gland is regulated by the interaction of genetic mechanisms, internal epigenetic (enzyme systems, hormones) and exogenous factors. There is no doubt that there is a clear genetic program for the implementation of the complex process of embryonic development. The mechanisms regulating LG organogenesis initiate the work of a huge number of structural oncogenes, transcription and growth factors, etc. Studying the expression and selective activity of regulatory genes during organ development, their participation in the differentiation of different cell types is a current trend at the nexus of clinical genetics, molecular biology, embryology and immunocytochemistry. Due to its relatively simple structure and accessibility, human LG is a suitable object for potential application in regenerative medicine. Development of a universal protocol for obtaining functional differentiated secretory epithelium of LG capable of expressing tissue-specific markers is an urgent task. Determining the nature and origin of stem cells and progenitor cells will allow the isolation and multiplication of these cells in culture. After obtaining a functionally active culture of LG cells, it is possible to create a model of autoimmune diseases.
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Affiliation(s)
- T N Safonova
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - G V Zaitseva
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
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Chan CS, Laddha SV, Lewis PW, Koletsky MS, Robzyk K, Da Silva E, Torres PJ, Untch BR, Li J, Bose P, Chan TA, Klimstra DS, Allis CD, Tang LH. ATRX, DAXX or MEN1 mutant pancreatic neuroendocrine tumors are a distinct alpha-cell signature subgroup. Nat Commun 2018; 9:4158. [PMID: 30315258 PMCID: PMC6185985 DOI: 10.1038/s41467-018-06498-2] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 09/03/2018] [Indexed: 02/05/2023] Open
Abstract
The commonly mutated genes in pancreatic neuroendocrine tumors (PanNETs) are ATRX, DAXX, and MEN1. We genotyped 64 PanNETs and found 58% carry ATRX, DAXX, and MEN1 mutations (A-D-M mutant PanNETs) and this correlates with a worse clinical outcome than tumors carrying the wild-type alleles of all three genes (A-D-M WT PanNETs). We performed RNA sequencing and DNA-methylation analysis to reveal two distinct subgroups with one consisting entirely of A-D-M mutant PanNETs. Two genes differentiating A-D-M mutant from A-D-M WT PanNETs were high ARX and low PDX1 gene expression with PDX1 promoter hyper-methylation in the A-D-M mutant PanNETs. Moreover, A-D-M mutant PanNETs had a gene expression signature related to that of alpha-cells (FDR q-value < 0.009) of pancreatic islets including increased expression of HNF1A and its transcriptional target genes. This gene expression profile suggests that A-D-M mutant PanNETs originate from or transdifferentiate into a distinct cell type similar to alpha cells. In pancreatic neuroendocrine tumors (PanNETs) ATRX, DAXX, and MEN1 are commonly mutated (A-D-M mutant PanNETs). Here, the authors find in a cohort of PanNETS 58% are A-D-M mutant PanNETs, with a worse clinical outcome and differences in gene expression and methylation compared to A-D-M wild type cases- these gene expression differences suggest that A-D-M mutant PanNETs potentially originate from a cell type similar to alpha cells.
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Affiliation(s)
- Chang S Chan
- Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, 08903, USA.,Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, 08901, USA
| | - Saurabh V Laddha
- Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, 08903, USA
| | - Peter W Lewis
- Epigenetics Theme, Wisconsin Institute for Discovery, University of Wisconsin, Madison, WI, USA
| | - Matthew S Koletsky
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY, 10065, USA
| | - Kenneth Robzyk
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Edaise Da Silva
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Paula J Torres
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Brian R Untch
- Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Janet Li
- Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Promita Bose
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Timothy A Chan
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - David S Klimstra
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY, 10065, USA
| | - Laura H Tang
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA.
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3
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Garg A, Zhang X. Lacrimal gland development: From signaling interactions to regenerative medicine. Dev Dyn 2017; 246:970-980. [PMID: 28710815 DOI: 10.1002/dvdy.24551] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/13/2017] [Accepted: 06/06/2017] [Indexed: 12/30/2022] Open
Abstract
The lacrimal gland plays a pivotal role in keeping the ocular surface lubricated, and protecting it from environmental exposure and insult. Dysfunction of the lacrimal gland results in deficiency of the aqueous component of the tear film, which can cause dryness of the ocular surface, also known as the aqueous-deficient dry eye disease. Left untreated, this disease can lead to significant morbidity, including frequent eye infections, corneal ulcerations, and vision loss. Current therapies do not treat the underlying deficiency of the lacrimal gland, but merely provide symptomatic relief. To develop more sustainable and physiological therapies, such as in vivo lacrimal gland regeneration or bioengineered lacrimal gland implants, a thorough understanding of lacrimal gland development at the molecular level is of paramount importance. Based on the structural and functional similarities between rodent and human eye development, extensive studies have been undertaken to investigate the signaling and transcriptional mechanisms of lacrimal gland development using mouse as a model system. In this review, we describe the current understanding of the extrinsic signaling interactions and the intrinsic transcriptional network governing lacrimal gland morphogenesis, as well as recent advances in the field of regenerative medicine aimed at treating dry eye disease. Developmental Dynamics 246:970-980, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Ankur Garg
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Departments of Ophthalmology, Pathology and Cell Biology, Columbia University, New York, New York
| | - Xin Zhang
- Departments of Ophthalmology, Pathology and Cell Biology, Columbia University, New York, New York
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Góes VC, Neves RH, Arnóbio A, Bernardo-Filho M, Machado-Silva JR. Streptozotocin (STZ) and schistosomiasis mansoni change the biodistribution of radiopharmaceutical sodium (99m)Tc-pertechnetate in mice. Nucl Med Biol 2016; 43:581-586. [PMID: 27438409 DOI: 10.1016/j.nucmedbio.2016.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 05/31/2016] [Accepted: 06/06/2016] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Technetium-99m ((99m)Tc) is a radionuclide commonly used in nuclear medicine to obtain (99m)Tc-radiopharmaceuticals, which can be used to evaluate either physiological processes or changes related to diseases. It is also used in some experimental studies. Streptozotocin (STZ) administration to rodents causes lesions in very early stages and induces severe and permanent diabetes. Most morbidity of schistosomiasis mansoni is attributed to a granulomatous inflammatory response and associated liver fibrosis. This study was designed to investigate whether STZ administration and schistosomiasis modify the biodistribution of the radiopharmaceutical sodium (99m)Tc-pertechnetate. METHODS Adult female mice were infected by exposure to 100Schistosoma mansoni cercariae (BH strain, Belo Horizonte, Brazil) and euthanized after nine weeks. STZ was administered by a single intraperitoneal injection of 100mg/kg body weight, 3 or 15days before euthanasia. Each animal received 100μl of sodium (Na) (99m)Tc-pertechnetate ((99m)TcO4(-)) (740kBq). The animals were divided into four groups: A, uninfected; B, infected; C, uninfected + STZ; and D, infected + STZ. Blood, brain, thyroid, heart, lungs, liver, spleen, pancreas and kidneys were removed. The radioactivity was counted and the percentage of the injected dose of Na(99m)TcO4 per gram of the organ (% ID/g) was determined. RESULTS Three days after the STZ injection, there was a decrease of Na(99m)TcO4 uptake by the liver, lungs, pancreas and kidneys (p<0.05) in group D when compared with group A. After 15days, the decrease of Na(99m)TcO4 uptake occurred also in the brain, thyroid, heart, spleen and blood (p<0.05) in group D. CONCLUSION We demonstrated modifications on the biodistribution of Na(99m)TcO4 due to STZ administration and schistosomiasis, possibly due to physiological alterations in some organs. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE The biodistribution of radiopharmaceutical Na(99m)TcO4 should be carefully evaluated in subjects with diabetes and/or schistosomiasis infection.
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Affiliation(s)
- Vanessa Coelho Góes
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Av. Professor Manoel de Abreu, 444, 5° Andar, Vila Isabel, 20511-070 Rio de Janeiro, RJ, Brazil
| | - Renata Heisler Neves
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Av. Professor Manoel de Abreu, 444, 5° Andar, Vila Isabel, 20511-070 Rio de Janeiro, RJ, Brazil
| | - Adriano Arnóbio
- Laboratório de Radiofarmácia Experimental, Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Av. 28 de Setembro, 87, 4° Andar fundos, Vila Isabel, 20551-030 Rio de Janeiro, RJ, Brazil
| | - Mario Bernardo-Filho
- Laboratório de Radiofarmácia Experimental, Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Av. 28 de Setembro, 87, 4° Andar fundos, Vila Isabel, 20551-030 Rio de Janeiro, RJ, Brazil
| | - José Roberto Machado-Silva
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Av. Professor Manoel de Abreu, 444, 5° Andar, Vila Isabel, 20511-070 Rio de Janeiro, RJ, Brazil.
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Nugroho WS, Kusindarta DL, Susetya H, Fitriana I, Mulyani GT, Fibrianto YH, Haryanto A, Budipitojo T. The structural and functional recovery of pancreatic β-cells in type 1 diabetes mellitus induced mesenchymal stem cell-conditioned medium. Vet World 2016; 9:535-9. [PMID: 27284233 PMCID: PMC4893728 DOI: 10.14202/vetworld.2016.535-539] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 04/22/2016] [Indexed: 01/27/2023] Open
Abstract
AIM Various studies have shown that secreted factors alone in culture medium without stem cell are capable of repairing tissues by itself in various conditions involving damaged tissue/organ. Therefore, this study was aimed to investigate the role of human umbilical cord mesenchymal stem cell-derived conditioned medium (CM) on the recovery of pancreatic β-cells in Wistar rats (Rattus norvegicus) with type 1 diabetes mellitus. MATERIALS AND METHODS The 0.05 ml CM induction was applied to the diabetic group of rats in weeks 1, 2, 3, and 4. 1 week after each CM induction, insulin concentration was analyzed using ELISA. The pancreas was divided into 3 regions, processed by paraffin method, stained with hematoxylin-eosin, and immunohistochemical method for insulin. RESULTS This study indicated the decrease in the total number of islets and insulin concentration after the injection of single dose of alloxan. The exocrine acini were also damaged. Microscopic observation detected the presence of small islets in the diabetic group 1 week after the first 0.05 ml CM induction. The number and size of the islets increased in line with the CM doses and time of inductions. Immunohistochemically, the presence of low intensity of insulin-positive cells could be recognized at the splenic and duodenal regions of the pancreas, but not gastric region, 1 week after the first and second 0.05 ml CM induction. The intensity of staining and the number of insulin-positive cells increased dramatically in 1 week after the third and fourth 0.05 ml of CM induction in all regions of the pancreas. The data of insulin blood concentration showed clear differences between the second and the fourth induction of 0.05 ml CM induction. CONCLUSIONS This study showed very strong evidence on the role of human umbilical cord mesenchymal stem cell-derived CM in recovering the pancreatic β-cells damage in Wistar rats (R. norvegicus) with type 1 diabetes mellitus, structurally and functionally.
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Affiliation(s)
- Widagdo Sri Nugroho
- Department of Veterinary Public Health, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Dwi Liliek Kusindarta
- Department of Anatomy, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Heru Susetya
- Department of Veterinary Public Health, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Ida Fitriana
- Department of Pharmacology, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Guntari Titik Mulyani
- Department of Internal Medicine, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Yuda Heru Fibrianto
- Department of Physiology, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Aris Haryanto
- Department of Biochemistry, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Teguh Budipitojo
- Department of Anatomy, Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
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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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Abu-Farha M, Al Madhoun A, Abubaker J. The Rise and the Fall of Betatrophin/ANGPTL8 as an Inducer of β-Cell Proliferation. J Diabetes Res 2016; 2016:4860595. [PMID: 27672665 PMCID: PMC5031879 DOI: 10.1155/2016/4860595] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 12/14/2022] Open
Abstract
Diabetes is a global health problem that is caused by impaired insulin production from pancreatic β-cells. Efforts to regenerate β-cells have been advancing rapidly in the past two decades with progress made towards identifying new agents that induce β-cells regeneration. ANGPTL8, also named betatrophin, has been recently identified as a hormone capable of inducing β-cells proliferation and increasing β-cells mass in rodents. Its discovery has been cherished as a breakthrough and a game changer in the field of β-cells regeneration. Initially, ANGPTL8 has been identified as atypical member of the angiopoietin-like protein family as a regulator of triglyceride in plasma through its interaction with ANGPTL3 and its regulation of lipoprotein lipase activity. In this review, we will review literature on the proposed role of ANGPTL8 in β-cells proliferation, the controversy regarding this role, and the emerging data questioning its involvement in β-cells proliferation. Additionally we will discuss new clinical data that describes its role in diabetes and the putative therapeutic targeting of this protein.
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Affiliation(s)
- Mohamed Abu-Farha
- Biochemistry and Molecular Biology Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
- *Mohamed Abu-Farha: and
| | | | - Jehad Abubaker
- Biochemistry and Molecular Biology Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
- *Jehad Abubaker:
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Puri S, Folias AE, Hebrok M. Plasticity and dedifferentiation within the pancreas: development, homeostasis, and disease. Cell Stem Cell 2014; 16:18-31. [PMID: 25465113 DOI: 10.1016/j.stem.2014.11.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cellular identity is established by genetic, epigenetic, and environmental factors that regulate organogenesis and tissue homeostasis. Although some flexibility in fate potential is beneficial to overall organ health, dramatic changes in cellular identity can have disastrous consequences. Emerging data within the field of pancreas biology are revising current beliefs about how cellular identity is shaped by developmental and environmental cues under homeostasis and stress conditions. Here, we discuss the changes occurring in cellular states upon fate modulation and address how our understanding of the nature of this fluidity is shaping therapeutic approaches to pancreatic disorders such as diabetes and cancer.
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Affiliation(s)
- Sapna Puri
- Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Alexandra E Folias
- Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Matthias Hebrok
- Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
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Lodh S, O’Hare EA, Zaghloul NA. Primary cilia in pancreatic development and disease. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2014; 102:139-58. [PMID: 24864023 PMCID: PMC4213238 DOI: 10.1002/bdrc.21063] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/30/2014] [Accepted: 03/30/2014] [Indexed: 01/04/2023]
Abstract
Primary cilia and their anchoring basal bodies are important regulators of a growing list of signaling pathways. Consequently, dysfunction in proteins associated with these structures results in perturbation of the development and function of a spectrum of tissue and cell types. Here, we review the role of cilia in mediating the development and function of the pancreas. We focus on ciliary regulation of major pathways involved in pancreatic development, including Shh, Wnt, TGF-β, Notch, and fibroblast growth factor. We also discuss pancreatic phenotypes associated with ciliary dysfunction, including pancreatic cysts and defects in glucose homeostasis, and explore the potential role of cilia in such defects.
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Affiliation(s)
- Sukanya Lodh
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Elizabeth A. O’Hare
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Norann A. Zaghloul
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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Pax4 and Arx Represent Crucial Regulators of the Development of the Endocrine Pancreas. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/981569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The development of the endocrine pancreas is under the control of highly orchestrated, cross-interacting transcription factors. Pancreas genesis is initiated by the emergence of a Pdx1/Ptf1a marked territory at the foregut/midgut junction. A small fraction of pancreatic fated cells activates the expression of the bHLH transcription factor Ngn3 triggering the endocrine cell program, thus giving rise to beta-, alpha-, delta-, PP-, and epsilon-cells, producing insulin, glucagon, somatostatin, pancreatic polypeptide, and ghrelin, respectively. Two transcription factors, Pax4 and Arx, play a crucial role in differential endocrine cell subtype specification. They were shown to be necessary and sufficient to endow endocrine progenitors with either a beta- or alpha-cell destiny. Interestingly, whereas the forced expression of Arx in beta-cells converts these into cells exhibiting alpha- and PP-cell characteristics, the sole expression of Pax4 in alpha-cells promotes alpha-cell-neogenesis and the acquisition of beta-cell features, the resulting beta-like cells being capable of counteracting chemically induced diabetes. Gaining new insights into the molecular mechanisms controlling Pax4 and Arx expression in the endocrine pancreas may therefore pave new avenues for the therapy of diabetes.
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