title: The Role of ARX in Human Pancreatic Endocrine Specification.
abstract: 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. ARX knockout hESCs retained pancreatic differentiation capacity and ARX knockout endocrine cells were biased toward somatostatin-positive cells (94% of endocrine cells) with reduced pancreatic polypeptide (rarely detected), glucagon (90% reduced) and insulin-positive (65% reduced) lineages. ARX knockout somatostatin-positive cells shared expression patterns with human fetal and adult δ-cells. Differentiated ARX knockout cells upregulated PAX4, NKX2.2, ISL1, HHEX, PCSK1, PCSK2 expression while downregulating PAX6 and IRX2. Re-expression of ARX in ARX knockout pancreatic progenitors reduced HHEX and increased PAX6 and insulin expression following differentiation. Taken together these data suggest that ARX plays a key role in pancreatic endocrine fate specification of pancreatic polypeptide, somatostatin, glucagon and insulin positive cells from hESCs.
authors.affiliation: Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Blair K
authors.initials: BK
authors.lastname: Gage
authors.affiliation: Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Ali
authors.initials: A
authors.lastname: Asadi
authors.affiliation: Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Baker
authors.affiliation: Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Travis D
authors.initials: TD
authors.lastname: Webber
authors.affiliation: Departments of Physiology, Pharmacology & Medicine, Child Health Research Institute, the University of Western Ontario, London, Ontario, Canada.
authors.forename: Rennian
authors.initials: R
authors.lastname: Wang
authors.affiliation: National Center of Neurology and Psychiatry, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Itoh
authors.affiliation: Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Hayashi
authors.affiliation: Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Miyata
authors.affiliation: Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Akashi
authors.affiliation: Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.|Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Kieffer
mesh_terms: D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D019070:Cell Lineage / Q000502:physiology*; D005934:Glucagon / Q000235:genetics / Q000378:metabolism; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D010191:Pancreatic Polypeptide / Q000235:genetics / Q000378:metabolism; D013004:Somatostatin / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: C469264:ARX protein, human; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D007328:Insulin; C000715631:NKX2-2 protein, human; D009687:Nuclear Proteins; C491709:PAX4 protein, human; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; D013004:Somatostatin; D010191:Pancreatic Polypeptide; D005934:Glucagon