Rizzoti K, Paquereau L, Shaw A, Knibiehler B, Audigier Y
Unité INSERM U-397, CHU Rangueil, Institut L. Bugnard, Bât. L3, 1, avenue Jean-Poulhès, 31054, Toulouse Cédex, France.
Mech Dev. 1998 Aug;76(1-2):19-31. doi: 10.1016/s0925-4773(98)00106-3.
We have examined the expression and function of the heterotrimeric GTP-binding protein Gq during early Xenopus embryogenesis. Abundant XGalphaq transcripts were detected in oocytes and early embryos by Northern blot analysis. In situ hybridization revealed that these transcripts are confined to the animal hemisphere of the mature oocyte and to the presumptive ectoderm of cleaving embryos. Microinjection at the two-cell stage of alphaq and Q209Lalphaq, a constitutively activated mutant, causes a disruption in ectodermal cell adhesion at late gastrulation. Dissociation/reaggregation experiments performed on animal cap explants clearly demonstrate that the Q209Lalphaq-induced phenotype occurs after reaggregation of the explants with a time-course similar to that observed in whole embryos. RT-PCR experiments performed on the explants from Q209Lalphaq-injected embryos revealed a selective decrease in the amount of EP-cadherin mRNA. Co-injection of EP-cadherin RNA, but also E-cadherin RNA, rescued the disaggregated phenotype. These data emphasize the functional link between Gq protein-coupled signalling pathways and cadherin molecules in the ectodermal layer during the morphogenetic movements of gastrulation.
我们研究了异源三聚体GTP结合蛋白Gq在非洲爪蟾胚胎早期发育过程中的表达及功能。通过Northern印迹分析在卵母细胞和早期胚胎中检测到大量的XGalphaq转录本。原位杂交显示，这些转录本局限于成熟卵母细胞的动物半球以及分裂胚胎的预定外胚层。在两细胞期显微注射alphaq和组成型激活突变体Q209Lalphaq，会导致原肠胚晚期外胚层细胞黏附受到破坏。对动物帽外植体进行的解离/重聚集实验清楚地表明，Q209Lalphaq诱导的表型在与整体胚胎中观察到的时间进程相似的外植体重聚集后出现。对注射了Q209Lalphaq的胚胎的外植体进行的RT-PCR实验显示，EP-钙黏蛋白mRNA的量选择性减少。共注射EP-钙黏蛋白RNA以及E-钙黏蛋白RNA，挽救了分散的表型。这些数据强调了在原肠胚形成的形态发生运动过程中，Gq蛋白偶联信号通路与外胚层中钙黏蛋白分子之间的功能联系。
