Saleem Saira, Li Jinming, Yee Siu-Pok, Fellows George F, Goodyer Cynthia G, Wang Rennian
Department of Physiology and Pharmacology, University of Western Ontario, London, Canada.
J Pathol. 2009 Oct;219(2):182-92. 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.
β1整合素与胶原基质的相互作用通过与粘着斑激酶（FAK）结合并启动MAPK/ERK信号传导来调节细胞存活，但在人类胎儿胰岛发育过程中，对这些信号通路知之甚少。本研究的目的是探讨β1整合素/FAK激活的MAPK/ERK通路是否调节人类胎儿胰岛细胞内分泌细胞标志物的表达和存活。使用β1整合素阻断抗体、β1整合素小干扰RNA（siRNA）和FAK表达载体，对在I型胶原上培养的分离的人类（胎龄18 - 21周）胰岛上皮细胞簇进行检测。干扰人类胎儿胰岛上皮细胞簇中的β1整合素功能导致细胞粘附显著减少，同时表达PDX - 1、胰岛素和胰高血糖素的细胞数量减少（p < 0.05）。β1整合素阻断使PDX - 1(+)细胞中的粘着斑连接紊乱，并降低FAK和ERK1/2信号的激活，同时裂解的半胱天冬酶9和3的表达增加（p < 0.01）。在β1整合素表达的小干扰RNA敲低后获得了类似的结果。相反，FAK的过表达不仅增加了磷酸化ERK以及PDX - 1、胰岛素和胰高血糖素的表达（p < 0.05），而且消除了β1整合素阻断导致的磷酸化ERK和PDX - 1的降低。本研究表明，β1整合素激活的FAK/ERK信号级联参与人类胎儿胰腺胰岛细胞的分化和存活。
