The Rho-Rock-Myosin signaling axis determines cell-cell integrity of self-renewing pluripotent stem cells

PLoS One. 2008 Aug 20;3(8):e3001. doi: 10.1371/journal.pone.0003001.


Background: Embryonic stem (ES) cells self-renew as coherent colonies in which cells maintain tight cell-cell contact. Although intercellular communications are essential to establish the basis of cell-specific identity, molecular mechanisms underlying intrinsic cell-cell interactions in ES cells at the signaling level remain underexplored.

Methodology/principal findings: Here we show that endogenous Rho signaling is required for the maintenance of cell-cell contacts in ES cells. siRNA-mediated loss of function experiments demonstrated that Rock, a major effector kinase downstream of Rho, played a key role in the formation of cell-cell junctional assemblies through regulation of myosin II by controlling a myosin light chain phosphatase. Chemical engineering of this signaling axis by a Rock-specific inhibitor revealed that cell-cell adhesion was reversibly controllable and dispensable for self-renewal of mouse ES cells as confirmed by chimera assay. Furthermore, a novel culture system combining a single synthetic matrix, defined medium, and the Rock inhibitor fully warranted human ES cell self-renewal independent of animal-derived matrices, tight cell contacts, or fibroblastic niche-forming cells as determined by teratoma formation assay.

Conclusions/significance: These findings demonstrate an essential role of the Rho-Rock-Myosin signaling axis for the regulation of basic cell-cell communications in both mouse and human ES cells, and would contribute to advance in medically compatible xeno-free environments for human pluripotent stem cells.

Publication types

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

MeSH terms

  • Animals
  • Cell Adhesion / physiology
  • Cell Communication / physiology*
  • Embryonic Stem Cells / physiology
  • Mice
  • Microscopy, Confocal
  • Myosin Type II / physiology*
  • Pluripotent Stem Cells / physiology*
  • RNA, Small Interfering / genetics
  • Signal Transduction
  • rho-Associated Kinases / physiology*


  • RNA, Small Interfering
  • rho-Associated Kinases
  • Myosin Type II