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

Harb N, Archer TK, Sato N - PLoS ONE (2008)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of California Riverside, Riverside, California, United States of America.

ABSTRACT

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.

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Related in: MedlinePlus

A model summarizing the Rho-Rock-Myosin signaling pathway that regulates basic cell-cell interactions in ES cells.Chemicals and siRNAs used in the study are highlighted in red and asterisks, respectively. Dotted lines indicate potential mechanistic interactions within or between the cell-integrity and self-renewal pathways, although further investigations are required to address these possibilities. Arrows denote activation and bars indicate inhibition.
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pone-0003001-g007: A model summarizing the Rho-Rock-Myosin signaling pathway that regulates basic cell-cell interactions in ES cells.Chemicals and siRNAs used in the study are highlighted in red and asterisks, respectively. Dotted lines indicate potential mechanistic interactions within or between the cell-integrity and self-renewal pathways, although further investigations are required to address these possibilities. Arrows denote activation and bars indicate inhibition.

Mentions: To date several signaling pathways have been identified as the regulators for self-renewal in ES cells. As some of them are known to crosstalk with Rho or Rock signaling in mammalian cell lines [54]–[56], it is possible that the intrinsic cell-cell interactions in ES cells are also under the control of pluripotency regulators through modulating the Rho-Rock cascade. Intriguingly, activation of the Wnt/GSK-3 pathway by a synthetic compound, 6-bromoindirubin-3′-oxime (BIO) [57] substantially affected the cell-cell contact states in ES cells (unpublished observation) indicating the potential molecular link between self-renewal and intercellular communication systems in pluripotent stem cells at the signaling level (Figure 7).


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

Harb N, Archer TK, Sato N - PLoS ONE (2008)

A model summarizing the Rho-Rock-Myosin signaling pathway that regulates basic cell-cell interactions in ES cells.Chemicals and siRNAs used in the study are highlighted in red and asterisks, respectively. Dotted lines indicate potential mechanistic interactions within or between the cell-integrity and self-renewal pathways, although further investigations are required to address these possibilities. Arrows denote activation and bars indicate inhibition.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2500174&req=5

pone-0003001-g007: A model summarizing the Rho-Rock-Myosin signaling pathway that regulates basic cell-cell interactions in ES cells.Chemicals and siRNAs used in the study are highlighted in red and asterisks, respectively. Dotted lines indicate potential mechanistic interactions within or between the cell-integrity and self-renewal pathways, although further investigations are required to address these possibilities. Arrows denote activation and bars indicate inhibition.
Mentions: To date several signaling pathways have been identified as the regulators for self-renewal in ES cells. As some of them are known to crosstalk with Rho or Rock signaling in mammalian cell lines [54]–[56], it is possible that the intrinsic cell-cell interactions in ES cells are also under the control of pluripotency regulators through modulating the Rho-Rock cascade. Intriguingly, activation of the Wnt/GSK-3 pathway by a synthetic compound, 6-bromoindirubin-3′-oxime (BIO) [57] substantially affected the cell-cell contact states in ES cells (unpublished observation) indicating the potential molecular link between self-renewal and intercellular communication systems in pluripotent stem cells at the signaling level (Figure 7).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of California Riverside, Riverside, California, United States of America.

ABSTRACT

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.

Show MeSH
Related in: MedlinePlus