Rho differentially regulates the Hippo pathway by modulating the interaction between Amot and Nf2 in the blastocyst

Abstract

The Hippo pathway modulates the transcriptional activity of Yap to regulate the differentiation of the inner cell mass (ICM) and the trophectoderm (TE) in blastocysts. Yet how Hippo signaling is differentially regulated in ICM and TE cells is poorly understood. Through an inhibitor/activator screen, we have identified Rho as a negative regulator of Hippo in TE cells, and PKA as a positive regulator of Hippo in ICM cells. We further elucidated a novel mechanism by which Rho suppresses Hippo, distinct from the prevailing view that Rho inhibits Hippo signaling through modulating cytoskeleton remodeling and/or cell polarity. Active Rho prevents the phosphorylation of Amot Ser176, thus stabilizing the interaction between Amot and F-actin, and restricting the binding between Amot and Nf2. Moreover, Rho attenuates the interaction between Amot and Nf2 by binding to the coiled-coil domain of Amot. By blocking the association of Nf2 and Amot, Rho suppresses Hippo in TE cells.

HIPPO signaling resolves embryonic cell fate conflicts during establishment of pluripotency in vivo

“…Several direct and indirect targets of ROCK1/2 kinases in the early embryo have been described ( Alarcon and Marikawa, 2018 ; Shi et al, 2017 ). Among these is YAP1, a transcriptional partner of TEAD4 ( Nishioka et al, 2009 ), since ROCK activity is required for the nuclear localization of YAP1 ( Kono et al, 2014 ).…”

Hippo signalling during development

“…Cells then undergo asymmetric divisions that produce polarised and unpolarised cells, which will specify the TE or ICM lineages, respectively (Anani et al, 2014). The apical domain in polarised TE cells promotes YAP activity by sequestering Amot away from the basolateral domain, where it promotes activity of the core kinase cascade along with Nf2 (Cockburn et al, 2013;Hirate et al, 2015;Shi et al, 2017) and binds to YAP to limit nuclear import (Leung and Zernicka-Goetz, 2013). Polar cells also have higher cortical tension (Maître et al, 2016), and the change in Amot localisation could be mediated through an increase in F-actin at the apical domain (Anani et al, 2014;Leung and Zernicka-Goetz, 2013).…”

A tale of two cell-fates: role of the Hippo signaling pathway and transcription factors in early lineage formation in mouse preimplantation embryos

“…Several studies have also shown that Rho and Rho-associated coiled-coil kinases 1 and 2 (ROCK1 and ROCK2) are necessary for lineage formation by negatively regulating the Hippo pathway ( Kono et al , 2014 ; Shi et al , 2017 ; Alarcon and Marikawa, 2018 ). ROCK is activated by Rho small GTPases and then it phosphorylates a variety of targets involved in modulation of cellular processes such as cell polarity and gene expression ( Amano et al , 2010 ; Julian and Olson, 2014 ).…”