Objective To investigate the role of cytoplasmic domain of integrin alphaⅡb in platelet signal transduction. Methods Binding capacity of integrin alphaⅡb R995A to antibody platelet activation complex-1 (PAC-1) and p...Objective To investigate the role of cytoplasmic domain of integrin alphaⅡb in platelet signal transduction. Methods Binding capacity of integrin alphaⅡb R995A to antibody platelet activation complex-1 (PAC-1) and pp125 focal adhesion kinase (FAK) phosphorylation of cells were detected by flow cytometry, immune precipitation, and Western blotting. Results Without activation, wild-type alphaⅡbbeta3 Chinese hamster ovary (CHO) cells failed to bind to PAC-1, but mutant chimera alphaⅡb R995A beta3 CHO cells were able to bind with PAC-1. Furthermore, phosphorylation of pp125 (FAK) in wild-type alphaⅡbbeta3 CHO cells occured only when cells were adhered to fibrinogen, but could not be detected in bovine serum albumin suspension. However in the mutant chimera group, it could be detected in both conditions. Conclusion The mutation in integrin alphaⅡb R995A alters its affinity state as a receptor, thus also mediating cytoplasmic signal transduction leading to the phosphorylation of pp125 (FAK) without ligand binding.展开更多
Mouse embryo implantation is a complex process that includes trophoblast cells derived from ectoplacental cone (EPC) adhesion to and migration through the extracellular matrix (ECM) of uterine endometrium and invasion...Mouse embryo implantation is a complex process that includes trophoblast cells derived from ectoplacental cone (EPC) adhesion to and migration through the extracellular matrix (ECM) of uterine endometrium and invasion into the decidua. At the time of implantation, fibronectin (FN) is abundant in the decidua and is distributed pericellularly around each individual stromal cell, and its receptor (integrin α-5β-1) expression on trophoblast populations is up-regulated. The focal adhesion kinase, a 125 ku protein tyrosine kinase (pp125 FAK), is tyrosine phosphorylated upon integrin engagement with its ECM ligand, and its tyrosine phosphorylation sites then serve as the binding sites which couple it with cellular proteins that contain Src SH2 or SH3 domains. Through these linkages, pp125 FAK may integrate multiple signals triggered by integrins. The model of EPC culture %in vitro% was used to study the expression, distribution and function of pp125 FAK during EPC outgrowth on FN. Results indicated that, pp125 FAK primarily expressed and distributed in cellular focal adhesions of the front edge of trophoblast outgrowth from EPC, and was localized in the peripheral region of the individual migrating trophblast cell; antibody or antisense oligodeoxynucleotide to pp125 FAK inhibited EPC attachment and outgrowth, as well as trophoblast cells spreading and migration. This experiment demonstrated that pp125 FAK as an integrin-mediated signaling molecule was involved in EPC outgrowth %in vitro%, and played an important role during trophoblast cells interaction with FN.展开更多
文摘Objective To investigate the role of cytoplasmic domain of integrin alphaⅡb in platelet signal transduction. Methods Binding capacity of integrin alphaⅡb R995A to antibody platelet activation complex-1 (PAC-1) and pp125 focal adhesion kinase (FAK) phosphorylation of cells were detected by flow cytometry, immune precipitation, and Western blotting. Results Without activation, wild-type alphaⅡbbeta3 Chinese hamster ovary (CHO) cells failed to bind to PAC-1, but mutant chimera alphaⅡb R995A beta3 CHO cells were able to bind with PAC-1. Furthermore, phosphorylation of pp125 (FAK) in wild-type alphaⅡbbeta3 CHO cells occured only when cells were adhered to fibrinogen, but could not be detected in bovine serum albumin suspension. However in the mutant chimera group, it could be detected in both conditions. Conclusion The mutation in integrin alphaⅡb R995A alters its affinity state as a receptor, thus also mediating cytoplasmic signal transduction leading to the phosphorylation of pp125 (FAK) without ligand binding.
文摘Mouse embryo implantation is a complex process that includes trophoblast cells derived from ectoplacental cone (EPC) adhesion to and migration through the extracellular matrix (ECM) of uterine endometrium and invasion into the decidua. At the time of implantation, fibronectin (FN) is abundant in the decidua and is distributed pericellularly around each individual stromal cell, and its receptor (integrin α-5β-1) expression on trophoblast populations is up-regulated. The focal adhesion kinase, a 125 ku protein tyrosine kinase (pp125 FAK), is tyrosine phosphorylated upon integrin engagement with its ECM ligand, and its tyrosine phosphorylation sites then serve as the binding sites which couple it with cellular proteins that contain Src SH2 or SH3 domains. Through these linkages, pp125 FAK may integrate multiple signals triggered by integrins. The model of EPC culture %in vitro% was used to study the expression, distribution and function of pp125 FAK during EPC outgrowth on FN. Results indicated that, pp125 FAK primarily expressed and distributed in cellular focal adhesions of the front edge of trophoblast outgrowth from EPC, and was localized in the peripheral region of the individual migrating trophblast cell; antibody or antisense oligodeoxynucleotide to pp125 FAK inhibited EPC attachment and outgrowth, as well as trophoblast cells spreading and migration. This experiment demonstrated that pp125 FAK as an integrin-mediated signaling molecule was involved in EPC outgrowth %in vitro%, and played an important role during trophoblast cells interaction with FN.
