Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma.

Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma. Research Abstract Details 

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Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma. Abstract Text:

Norma Marchesini,Jeffrey A Jones,Yusuf A Hannun,Norma Marchesini,Jeffrey A Jones,Yusuf A Hannun,

It was previously observed that cell confluence induced up-regulation of neutral sphingomyelinase 2 (nSMase2) and increased ceramide levels [Marchesini N., Osta W., Bielawski J., Luberto C., Obeid L.M. and Hannun Y.A. (2004) J. Biol. Chem., 279, 25101-11]. In this study, we show that, in MCF7 cells, confluence induces the dephosphorylation of phosphorylated-beta-catenin at threonine41/serine45. The effect of confluence on beta-catenin dephosphorylation was prevented by down regulation of nSMase2 using siRNA; reciprocally, exogenous addition of short or very long chain ceramides induced dephosphorylation of beta-catenin. The serine/threonine protein phosphatase inhibitors calyculin A and okadaic acid prevented beta-catenin dephosphorylation during confluence. The specific phosphatase involved was determined by studies using siRNA against the major serine/threonine phosphatases, and the results showed that a specific siRNA against PP1cgamma prevented dephosphorylation of beta-catenin. Moreover, exogenous ceramides and confluence were found to induce the translocation of PP1cgamma to the plasma membrane. All together these results establish: A) a specific intracellular pathway involving the activation of PP1 to mediate the effects of confluence-induced beta-catenin dephosphorylation and B) PP1 as a lipid-regulated protein phosphatase downstream of nSMase2/ceramide. Finally, evidence is provided for a role for this pathway in regulating cell motility during confluence.

Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma. Publishing Authors By Initials

N Marchesini,JA Jones,YA Hannun,N Marchesini,JA Jones,YA Hannun,

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Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma. Journal Published:

PUBLICATION TYPE: Journal Article

Journal: Biochimica et biophysica acta

VOLUME: 1771

Page Numbers: 1418-28

Journal Abbreviation: Biochim. Biophys. Acta

ISSN: 0006-3002

DAY: 8

MONTH: 11

YEAR: 2007

Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma. Information

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LANGUAGE: eng

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Grant and Affiliation Information for Confluence induced threonine41/serine45 phospho-beta-catenin dephosphorylation via ceramide-mediated activation of PP1cgamma.

AFFILIATION: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 175 Ashley Ave., POB 250509, Charleston, SC 29425, USA.

Country: Netherlands

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MEDLINETA: Biochim Biophys Acta

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