title: SOX9 regulates endocrine cell differentiation during human fetal pancreas development.
abstract: The transition of pancreatic progenitor cells to mature endocrine cells is regulated by the sequential activation and interaction of several transcription factors. In mice, the transcription factor Sox9 has been shown to support endocrine cell differentiation. However, the functional role of SOX9 during pancreas development in the human has yet to be determined. The present study was to characterize SOX9 expression during human fetal pancreas development and examine its functional role by transfection with SOX9 siRNA or SOX9 expression vectors. Here we report that SOX9 was most frequently expressed in PDX1(+) cells (60-83%) and least in mature endocrine cells (<1-14%). The proliferation of SOX9(+) cells was significantly higher at 8-10 weeks than at 14-21 weeks (p<0.05) or 20-21 weeks (p<0.01). SOX9 frequently co-localized with FOXA2, NGN3 and transcription factors linked to NGN3 (NKX2.2, NKX6.1, PAX6). siRNA knockdown of SOX9 significantly decreased islet-epithelial cell proliferation, NGN3, NKX6.1, PAX6 and INS mRNA levels and the number of NGN3(+) and insulin(+) cells (p<0.05) while increasing GCG mRNA and glucagon(+) cells (p<0.05). Examination of SOX9 associated signaling pathways revealed a decrease in phospho-Akt (p<0.01), phospho-GSK3β (p<0.01) and cyclin D1 (p<0.01) with a decrease in nuclear β-catenin(+) (p<0.05) cells following SOX9 siRNA knockdown. In contrast, over-expression of SOX9 significantly increased the number of islet cells proliferating, NGN3, NKX6.1, PAX6 and INS mRNA levels, the phospho-Akt/GSK3β cascade and the number of insulin(+) cells. Our results demonstrated that SOX9 is important for the expression of NGN3 and molecular markers of endocrine cell differentiation in the human fetal pancreas.
authors: Children's Health Research Institute, University of Western Ontario, London, ON, Canada.
authors: Erin
authors: E
authors: McDonald
authors: Jinming
authors: J
authors: Li
authors: Mansa
authors: M
authors: Krishnamurthy
authors: George F
authors: GF
authors: Fellows
authors: Cynthia G
authors: CG
authors: Goodyer
authors: Rennian
authors: R
authors: Wang
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009687:Nuclear Proteins; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010179:Pancreas / Q000166:cytology / Q000196:embryology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D055758:SOX9 Transcription Factor / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors; D014162:Transfection
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D051058:Oncogene Protein v-akt; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; D014157:Transcription Factors; C498695:NEUROG3 protein, human; C000715631:NKX2-2 protein, human; C000715627:Nkx2-2 protein, mouse; C527932:SOX9 protein, human; C000605506:GSK3B protein, human; C000605507:Gsk3b protein, mouse