This Article Full Text (PDF) Other Versions of this Article: MCB.00867-07v1 28/13/4215    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Hagan, G. N. Articles by Czech, M. P. PubMed PubMed Citation Articles by Hagan, G. N. Articles by Czech, M. P.

 Previous Article  |  Next Article 

Mol. Cell. Biol. doi:10.1128/MCB.00867-07
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

A Rictor-Myo1c complex participates in dynamic cortical actin events in 3T3-L1 adipocytes

Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; Department of Molecular Biology and the Diabetes Unit and Medical Services, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Molecular Physiology and Biophysics and Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA

^* To whom correspondence should be addressed. Email: Michael.Czech{at}umassmed.edu.

	Abstract

Insulin signaling through PI 3-kinase activates the protein kinase Akt through phosphorylation of its threonine 308 and serine 473 residues by the PDK1 protein kinase and the Rictor-mTOR complex (mTORC2), respectively. Remarkably, we show here that the protein Rictor is also present in cultured adipocytes in complexes containing Myo1c, a molecular motor that promotes cortical actin remodeling. Interestingly, the Rictor-Myo1c complex is biochemically distinct from the previously reported Rictor-mTOR complex (mTORC2), and can be immunoprecipitated independently of mTORC2. Furthermore, while RNAi-directed silencing of Rictor results in the expected attenuation of Akt phosphorylation at serine 473, depletion of Myo1c is without effect. In contrast, loss of either Rictor or Myo1c inhibits phosphorylation of the actin filament regulatory protein paxillin at tyrosine 118. Furthermore, Myo1c-induced membrane ruffling of 3T3-L1 adipocytes is also compromised following Rictor knockdown. Interestingly, neither the mTORC2 inhibitor rapamycin nor the PI 3-kinase inhibitor wortmannin affects paxillin tyrosine 118 phosphorylation. Taken together, our findings suggest the Rictor-Myo1c complex is distinct from the Rictor-mTOR complex and that Myo1c, in conjunction with Rictor, participates in cortical actin remodeling events.