beta1 integrin/FAK/ERK signalling pathway is essential for human fetal islet cell differentiation and survival

• Published in: The Journal of pathology 2009-10, Vol.219 (2), p.182-192
• Main Authors: Saleem, Saira, Li, Jinming, Yee, Siu-Pok, Fellows, George F, Goodyer, Cynthia G, Wang, Rennian
• Format: Article
• Language: English
• Subjects: Cell Adhesion - physiology; Cell Differentiation - physiology; Cell Survival - physiology; Cells, Cultured; Epithelial Cells - cytology; Fetal Development - physiology; Focal Adhesion Kinase 1 - physiology; Gene Knockdown Techniques; Humans; Integrin beta1 - genetics; Integrin beta1 - physiology; Islets of Langerhans - cytology; Islets of Langerhans - embryology; MAP Kinase Signaling System - physiology
• ISSN: 1096-9896
• DOI: 10.1002/path.2577

beta1 integrin and collagen matrix interactions regulate the survival of cells by associating with focal adhesion kinase (FAK) and initiating MAPK/ERK signalling, but little is known about these signalling pathways during human fetal islet ontogeny. The purpose of this study was to investigate whether beta1 integrin/FAK activation of the MAPK/ERK pathway regulates human fetal islet cell expression of endocrine cell markers and survival. Isolated human (18-21 weeks fetal age) islet-epithelial cell clusters, cultured on collagen I, were examined using beta1 integrin blocking antibody, beta1 integrin siRNA and FAK expression vector. Perturbing beta1 integrin function in the human fetal islet-epithelial cell clusters resulted in a marked decrease in cell adhesion, in parallel with a reduction in the number of cells expressing PDX-1, insulin and glucagon (p < 0.05). beta1 integrin blockade disorganized focal adhesion contacts in the PDX-1(+) cells and decreased activation of FAK and ERK1/2 signalling in parallel with an increase in expression of cleaved caspases 9 and 3 (p < 0.01). Similar results were obtained following an siRNA knock-down of beta1 integrin expression. In contrast, over-expression of FAK not only increased phospho-ERK and the expression of PDX-1, insulin and glucagon (p < 0.05) but also abrogated the decreases in phospho-ERK and PDX-1 by beta1 integrin blockade. This study demonstrates that activation of the FAK/ERK signalling cascade by beta1 integrin is involved in the differentiation and survival of human fetal pancreatic islet cells.