Polarity-dependent distribution of angiomotin localizes Hippo signaling in preimplantation embryos

Curr Biol. 2013 Jul 8;23(13):1181-94. doi: 10.1016/j.cub.2013.05.014. Epub 2013 Jun 20.

Abstract

Background: In preimplantation mouse embryos, the first cell fate specification to the trophectoderm or inner cell mass occurs by the early blastocyst stage. The cell fate is controlled by cell position-dependent Hippo signaling, although the mechanisms underlying position-dependent Hippo signaling are unknown.

Results: We show that a combination of cell polarity and cell-cell adhesion establishes position-dependent Hippo signaling, where the outer and inner cells are polar and nonpolar, respectively. The junction-associated proteins angiomotin (Amot) and angiomotin-like 2 (Amotl2) are essential for Hippo pathway activation and appropriate cell fate specification. In the nonpolar inner cells, Amot localizes to adherens junctions (AJs), and cell-cell adhesion activates the Hippo pathway. In the outer cells, the cell polarity sequesters Amot from basolateral AJs to apical domains, thereby suppressing Hippo signaling. The N-terminal domain of Amot is required for actin binding, Nf2/Merlin-mediated association with the E-cadherin complex, and interaction with Lats protein kinase. In AJs, S176 in the N-terminal domain of Amot is phosphorylated by Lats, which inhibits the actin-binding activity, thereby stabilizing the Amot-Lats interaction to activate the Hippo pathway.

Conclusions: We propose that the phosphorylation of S176 in Amot is a critical step for activation of the Hippo pathway in AJs and that cell polarity disconnects the Hippo pathway from cell-cell adhesion by sequestering Amot from AJs. This mechanism converts positional information into differential Hippo signaling, thereby leading to differential cell fates.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adherens Junctions / metabolism
  • Animals
  • Blastocyst / metabolism*
  • Cell Adhesion
  • Cell Polarity*
  • Gene Expression Regulation, Developmental*
  • Intercellular Signaling Peptides and Proteins / genetics*
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Mice
  • Microfilament Proteins / genetics*
  • Microfilament Proteins / metabolism
  • Phosphorylation
  • Polymerase Chain Reaction
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Serine-Threonine Kinases / metabolism
  • Signal Transduction*
  • Tumor Suppressor Proteins / metabolism

Substances

  • Amot protein, mouse
  • Intercellular Signaling Peptides and Proteins
  • Microfilament Proteins
  • Tumor Suppressor Proteins
  • Lats1 protein, mouse
  • Hippo protein, mouse
  • LATS2 protein, mouse
  • Protein-Serine-Threonine Kinases