Integrin B1 coordinates survival and morphogenesis of the embryonic lineage upon implantation and pluripotency transition

Abstract

At implantation, the embryo establishes contacts with the maternal endometrium. This stage is associated with a high incidence of preclinical pregnancy losses. While the maternal factors underlying uterine receptivity have been investigated, the signals required by the embryo for successful peri- implantation development remain elusive. To explore these, we studied integrin B1 signaling, as embryos deficient for this receptor degenerate at implantation. We demonstrate that the coordinated action of pro-survival signals and localized actomyosin suppression via integrin B1 permits development of the embryo beyond implantation. Failure of either process leads to developmental arrest and apoptosis. Pharmacological stimulation through FGF2 and IGF1, coupled with ROCK-mediated actomyosin inhibition rescues the deficiency of integrin B1, promoting progression to post-implantation stages. Mutual exclusion between integrin B1 and actomyosin seems to be conserved in the human embryo, suggesting the possibility that these mechanisms could also underlie the transition of the human epiblast from pre- to post-implantation.