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Arx AND Pax4

Maria J Lima, Kenneth R Muir, Hilary M Docherty, Neil W A McGowan, Shareen Forbes, Yves Heremans, Harry Heimberg, John Casey, Kevin Docherty
Transcription factor mediated lineage reprogramming of human pancreatic exocrine tissue could conceivably provide an unlimited supply of islets for transplantation in the treatment of diabetes. Exocrine tissue can be efficiently reprogrammed to islet-like cells using a cocktail of transcription factors: Pdx1, Ngn3, MafA and Pax4 in combination with growth factors. We show here that overexpression of exogenous Pax4 in combination with suppression of the endogenous transcription factor ARX considerably enhances the production of functional insulin-secreting β-like cells with concomitant suppression of α-cells...
2016: PloS One
Orr Friedman-Mazursky, Ran Elkon, Shimon Efrat
Ex-vivo expansion of adult human islet β cells has been evaluated for generation of abundant insulin-producing cells for transplantation; however, lineage-tracing has demonstrated that this process results in β-cell dedifferentiation. Redifferentiation of β-cell-derived (BCD) cells can be achieved using a combination of soluble factors termed Redifferentiation Cocktail (RC); however, this treatment leads to redifferentiation of only a fraction of BCD cells. This study aimed at improving redifferentiation efficiency by affecting the balance of islet progenitor-cell transcription factors activated by RC treatment...
February 9, 2016: Scientific Reports
Blair K Gage, Ali Asadi, Robert K Baker, Travis D Webber, Rennian Wang, Masayuki Itoh, Masaharu Hayashi, Rie Miyata, Takumi Akashi, Timothy J Kieffer
The in vitro differentiation of human embryonic stem cells (hESCs) offers a model system to explore human development. Humans with mutations in the transcription factor Aristaless Related Homeobox (ARX) often suffer from the syndrome X-linked lissencephaly with ambiguous genitalia (XLAG), affecting many cell types including those of the pancreas. Indeed, XLAG pancreatic islets lack glucagon and pancreatic polypeptide-positive cells but retain somatostatin, insulin, and ghrelin-positive cells. To further examine the role of ARX in human pancreatic endocrine development, we utilized genomic editing in hESCs to generate deletions in ARX...
2015: PloS One
Tiziana Napolitano, Fabio Avolio, Monica Courtney, Andhira Vieira, Noémie Druelle, Nouha Ben-Othman, Biljana Hadzic, Sergi Navarro, Patrick Collombat
The embryonic development of the pancreas is orchestrated by a complex and coordinated transcription factor network. Neurogenin3 (Neurog3) initiates the endocrine program by activating the expression of additional transcription factors driving survival, proliferation, maturation and lineage allocation of endocrine precursors. Among the direct targets of Neurog3, Pax4 appears as one of the key regulators of β-cell specification. Indeed, mice lacking Pax4 die a few days postpartum, as they develop severe hyperglycemia due to the absence of mature pancreatic β-cells...
August 2015: Seminars in Cell & Developmental Biology
Danielle Andrzejewski, Melissa L Brown, Nathan Ungerleider, Amy Burnside, Alan L Schneyer
TGFβ superfamily ligands, receptors, and second messengers, including activins A and B, have been identified in pancreatic islets and proposed to have important roles regulating development, proliferation, and function. We previously demonstrated that Fstl3 (an antagonist of activin activity) null mice have larger islets with β-cell hyperplasia and improved glucose tolerance and insulin sensitivity in the absence of altered β-cell proliferation. This suggested the hypothesis that increased activin signaling influences β-cell expansion by destabilizing the α-cell phenotype and promoting transdifferentiation to β-cells...
July 2015: Endocrinology
Rachel J Salisbury, Bing Han, Rachel E Jennings, Andrew A Berry, Adam Stevens, Zainab Mohamed, Sarah A Sugden, Ronald De Krijger, Sarah E Cross, Paul P V Johnson, Melanie Newbould, Karen E Cosgrove, Karen Piper Hanley, Indraneel Banerjee, Mark J Dunne, Neil A Hanley
Diffuse congenital hyperinsulinism in infancy (CHI-D) arises from mutations inactivating the KATP channel; however, the phenotype is difficult to explain from electrophysiology alone. Here we studied wider abnormalities in the β-cell and other pancreatic lineages. Islets were disorganized in CHI-D compared with controls. PAX4 and ARX expression was decreased. A tendency toward increased NKX2.2 expression was consistent with its detection in two-thirds of CHI-D δ-cell nuclei, similar to the fetal pancreas, and implied immature δ-cell function...
September 2015: Diabetes
Blair K Gage, Robert K Baker, Timothy J Kieffer
Human embryonic stem cells (hESCs) are pluripotent and capable of generating new β-cells, but current in vitro differentiation protocols generally fail to produce mature, glucose-responsive, unihormonal β-cells. Instead, these methods tend to produce immature polyhormonal endocrine cells which mature in vivo into glucagon-positive α-cells. PAX4 is an established transcription factor in β-cell development and function, and is capable of converting glucagon-positive cells to insulin-positive cells in mice...
2014: Islets
Blair K Gage, Robert K Baker, Timothy J Kieffer
Human embryonic stem cells (hESCs) are pluripotent and capable of generating new β cells, but current in vitro differentiation protocols generally fail to produce mature, glucose-responsive, unihormonal β cells. Instead, these methods tend to produce immature polyhormonal endocrine cells which mature in vivo into glucagon positive α cells. PAX4 is an established transcription factor in β-cell development and function, and is capable of converting glucagon positive cells to insulin positive cells in mice...
June 17, 2014: Islets
Blair K Gage, Travis D Webber, Timothy J Kieffer
Human embryonic stem cells (hESCs) have the ability to form cells derived from all three germ layers, and as such have received significant attention as a possible source for insulin-secreting pancreatic beta-cells for diabetes treatment. While considerable advances have been made in generating hESC-derived insulin-producing cells, to date in vitro-derived glucose-responsive beta-cells have remained an elusive goal. With the objective of increasing the in vitro formation of pancreatic endocrine cells, we examined the effect of varying initial cell seeding density from 1...
2013: PloS One
Monica Courtney, Elisabet Gjernes, Noémie Druelle, Christophe Ravaud, Andhira Vieira, Nouha Ben-Othman, Anja Pfeifer, Fabio Avolio, Gunter Leuckx, Sandra Lacas-Gervais, Fanny Burel-Vandenbos, Damien Ambrosetti, Jacob Hecksher-Sorensen, Philippe Ravassard, Harry Heimberg, Ahmed Mansouri, Patrick Collombat
Recently, it was demonstrated that pancreatic new-born glucagon-producing cells can regenerate and convert into insulin-producing β-like cells through the ectopic expression of a single gene, Pax4. Here, combining conditional loss-of-function and lineage tracing approaches, we show that the selective inhibition of the Arx gene in α-cells is sufficient to promote the conversion of adult α-cells into β-like cells at any age. Interestingly, this conversion induces the continuous mobilization of duct-lining precursor cells to adopt an endocrine cell fate, the glucagon(+) cells thereby generated being subsequently converted into β-like cells upon Arx inhibition...
October 2013: PLoS Genetics
Yaron Suissa, Judith Magenheim, Miri Stolovich-Rain, Ayat Hija, Patrick Collombat, Ahmed Mansouri, Lori Sussel, Beatriz Sosa-Pineda, Kyle McCracken, James M Wells, R Scott Heller, Yuval Dor, Benjamin Glaser
Neurogenin3(+) (Ngn3(+)) progenitor cells in the developing pancreas give rise to five endocrine cell types secreting insulin, glucagon, somatostatin, pancreatic polypeptide and ghrelin. Gastrin is a hormone produced primarily by G-cells in the stomach, where it functions to stimulate acid secretion by gastric parietal cells. Gastrin is expressed in the embryonic pancreas and is common in islet cell tumors, but the lineage and regulators of pancreatic gastrin(+) cells are not known. We report that gastrin is abundantly expressed in the embryonic pancreas and disappears soon after birth...
2013: PloS One
Takuya Sugiyama, Cecil M Benitez, Amar Ghodasara, Lucy Liu, Graeme W McLean, Jonghyeob Lee, Timothy A Blauwkamp, Roeland Nusse, Christopher V E Wright, Guoqiang Gu, Seung K Kim
Developmental biology is challenged to reveal the function of numerous candidate genes implicated by recent genome-scale studies as regulators of organ development and diseases. Recapitulating organogenesis from purified progenitor cells that can be genetically manipulated would provide powerful opportunities to dissect such gene functions. Here we describe systems for reconstructing pancreas development, including islet β-cell and α-cell differentiation, from single fetal progenitor cells. A strict requirement for native genetic regulators of in vivo pancreas development, such as Ngn3, Arx, and Pax4, revealed the authenticity of differentiation programs in vitro...
July 30, 2013: Proceedings of the National Academy of Sciences of the United States of America
Wenduo Ye, Wenbo Lin, Alan M Tartakoff, Qilin Ma, Tao Tao
Nucleocytoplasmic transport of transcription factors is essential in eukaryotes. We previously reported the presence of two functional NLSs in the homeodomain protein, aristaless-related homeobox (Arx) protein, which is a key transcriptional repressor of LMO1, SHOX2, and PAX4 during development. NLS2, that overlaps the homeodomain, is recognized directly by multiple importin βs, but not by importin αs. In this study, we found that the N-terminal NLS1 of Arx is targeted by multiple importin α proteins, including importin α3 and α5...
September 2013: Molecular and Cellular Biochemistry
Joachim Djiotsa, Vincianne Verbruggen, Jean Giacomotto, Minaka Ishibashi, Elisabeth Manning, Silke Rinkwitz, Isabelle Manfroid, Marianne L Voz, Bernard Peers
BACKGROUND: Genetic studies in mouse have demonstrated the crucial function of PAX4 in pancreatic cell differentiation. This transcription factor specifies β- and δ-cell fate at the expense of α-cell identity by repressing Arx gene expression and ectopic expression of PAX4 in α-cells is sufficient to convert them into β-cells. Surprisingly, no Pax4 orthologous gene can be found in chicken and Xenopus tropicalis raising the question of the function of pax4 gene in lower vertebrates such as in fish...
2012: BMC Developmental Biology
Joel F Habener, Violeta Stanojevic
This review considers the role of α-cells in β-cell generation and regeneration. We present recent evidence obtained from lineage-tracing studies showing that α-cells can serve as progenitors of β-cells and present a hypothetical model how injured β-cells might activate α-cells in adult islets to promote β-cell regeneration. β-cells appear to arise by way of their trans-differentiation from undifferentiated α progenitor cells, pro-α-cells, both during embryonic development of the islets and in the adult pancreas in response to β-cell injuries...
May 2012: Islets
Anthony Beucher, Elisabet Gjernes, Caitlin Collin, Monica Courtney, Aline Meunier, Patrick Collombat, Gérard Gradwohl
Intestinal hormones are key regulators of digestion and energy homeostasis secreted by rare enteroendocrine cells. These cells produce over ten different hormones including GLP-1 and GIP peptides known to promote insulin secretion. To date, the molecular mechanisms controlling the specification of the various enteroendocrine subtypes from multipotent Neurog3(+) endocrine progenitor cells, as well as their number, remain largely unknown. In contrast, in the embryonic pancreas, the opposite activities of Arx and Pax4 homeodomain transcription factors promote islet progenitor cells towards the different endocrine cell fates...
2012: PloS One
Simon Kordowich, Patrick Collombat, Ahmed Mansouri, Palle Serup
BACKGROUND: Nkx2.2 and Arx represent key transcription factors implicated in the specification of islet cell subtypes during pancreas development. Mice deficient for Arx do not develop any alpha-cells whereas beta- and delta-cells are found in considerably higher numbers. In Nkx2.2 mutant animals, alpha- and beta-cell development is severely impaired whereas a ghrelin-expressing cell population is found augmented.Notably, Arx transcription is clearly enhanced in Nkx2.2-deficient pancreata...
August 31, 2011: BMC Developmental Biology
Y Gosmain, C Cheyssac, M Heddad Masson, C Dibner, J Philippe
The glucagon gene is expressed in α-cells of the pancreas, L cells of the intestine and the hypothalamus. The determinants of the α-cell-specific expression of the glucagon gene are not fully characterized, although Arx, Pax6 and Foxa2 are critical for α-cell differentiation and glucagon gene expression; in addition, the absence of the β-cell-specific transcription factors Pdx1, Pax4 and Nkx6.1 may allow for the glucagon gene to be expressed. Pax6, along with cMaf and MafB, binds to the DNA control element G(1) which confers α-cell specificity to the promoter and to G(3) and potently activates glucagon gene transcription...
October 2011: Diabetes, Obesity & Metabolism
Josselin Soyer, Lydie Flasse, Wolfgang Raffelsberger, Anthony Beucher, Christophe Orvain, Bernard Peers, Philippe Ravassard, Julien Vermot, Marianne L Voz, Georg Mellitzer, Gérard Gradwohl
The transcription factor neurogenin 3 (Neurog3 or Ngn3) controls islet cell fate specification in multipotent pancreatic progenitor cells in the mouse embryo. However, our knowledge of the genetic programs implemented by Ngn3, which control generic and islet subtype-specific properties, is still fragmentary. Gene expression profiling in isolated Ngn3-positive progenitor cells resulted in the identification of the uncharacterized winged helix transcription factor Rfx6. Rfx6 is initially expressed broadly in the gut endoderm, notably in Pdx1-positive cells in the developing pancreatic buds, and then becomes progressively restricted to the endocrine lineage, suggesting a dual function in both endoderm development and islet cell differentiation...
January 2010: Development
Patrick Collombat, Xiaobo Xu, Philippe Ravassard, Beatriz Sosa-Pineda, Sébastien Dussaud, Nils Billestrup, Ole D Madsen, Palle Serup, Harry Heimberg, Ahmed Mansouri
We have previously reported that the loss of Arx and/or Pax4 gene activity leads to a shift in the fate of the different endocrine cell subtypes in the mouse pancreas, without affecting the total endocrine cell numbers. Here, we conditionally and ectopically express Pax4 using different cell-specific promoters and demonstrate that Pax4 forces endocrine precursor cells, as well as mature alpha cells, to adopt a beta cell destiny. This results in a glucagon deficiency that provokes a compensatory and continuous glucagon+ cell neogenesis requiring the re-expression of the proendocrine gene Ngn3...
August 7, 2009: Cell
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