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Vol. 19, Issue 5, 2328-2338, May 2008

This Article Full Text Full Text (PDF) Supplemental Materials All Versions of this Article: E07-10-1086v1 19/5/2328    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 Google Scholar Articles by Watanabe, S. Articles by Narumiya, S. PubMed PubMed Citation Articles by Watanabe, S. Articles by Narumiya, S.

mDia2 Induces the Actin Scaffold for the Contractile Ring and Stabilizes Its Position during Cytokinesis in NIH 3T3 Cells

Sadanori Watanabe^*, Yoshikazu Ando^*, Shingo Yasuda^*, Hiroshi Hosoya, Naoki Watanabe^*, Toshimasa Ishizaki^*, and Shuh Narumiya^*

*Department of Pharmacology, Kyoto University Faculty of Medicine, Kyoto 606-8501, Japan; and Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan

Submitted October 29, 2007; Revised January 25, 2008; Accepted February 7, 2008
Monitoring Editor: Fred Chang

mDia proteins are mammalian homologues of Drosophila diaphanous and belong to the formin family proteins that catalyze actin nucleation and polymerization. Although formin family proteins of nonmammalian species such as Drosophila diaphanous are essential in cytokinesis, whether and how mDia proteins function in cytokinesis remain unknown. Here we depleted each of the three mDia isoforms in NIH 3T3 cells by RNA interference and examined this issue. Depletion of mDia2 selectively increased the number of binucleate cells, which was corrected by coexpression of RNAi-resistant full-length mDia2. mDia2 accumulates in the cleavage furrow during anaphase to telophase, and concentrates in the midbody at the end of cytokinesis. Depletion of mDia2 induced contraction at aberrant sites of dividing cells, where contractile ring components such as RhoA, myosin, anillin, and phosphorylated ERM accumulated. Treatment with blebbistatin suppressed abnormal contraction, corrected localization of the above components, and revealed that the amount of F-actin at the equatorial region during anaphase/telophase was significantly decreased with mDia2 RNAi. These results demonstrate that mDia2 is essential in mammalian cell cytokinesis and that mDia2-induced F-actin forms a scaffold for the contractile ring and maintains its position in the middle of a dividing cell.

Address correspondence to: Shuh Narumiya (snaru{at}mfour.med.kyoto-u.ac.jp)