1. Flightless-I (Fli-I) regulates the actin assembly activity of diaphanous-related formins (DRFs) Daam1 and mDia1 in cooperation with active Rho GTPase.
- Author
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Higashi T, Ikeda T, Murakami T, Shirakawa R, Kawato M, Okawa K, Furuse M, Kimura T, Kita T, and Horiuchi H
- Subjects
- Actins chemistry, Actins genetics, Adaptor Proteins, Signal Transducing chemistry, Adaptor Proteins, Signal Transducing genetics, Animals, Biological Transport physiology, Cell Movement physiology, Formins, Guanosine Triphosphate chemistry, Guanosine Triphosphate genetics, Humans, Mice, Microfilament Proteins chemistry, Microfilament Proteins genetics, NIH 3T3 Cells, Receptors, Cytoplasmic and Nuclear chemistry, Receptors, Cytoplasmic and Nuclear genetics, Trans-Activators, rho GTP-Binding Proteins chemistry, rho GTP-Binding Proteins genetics, Actins metabolism, Adaptor Proteins, Signal Transducing metabolism, Guanosine Triphosphate metabolism, Microfilament Proteins metabolism, Receptors, Cytoplasmic and Nuclear metabolism, rho GTP-Binding Proteins metabolism
- Abstract
Eukaryotic cells dynamically reorganize the actin cytoskeleton to regulate various cellular activities, such as cell shape change, cell motility, cytokinesis, and vesicular transport. Diaphanous-related formins (DRFs), such as Daam1 and mDia1, play central roles in actin dynamics through assembling linear actin filaments. It has been reported that the GTP-bound active Rho binds directly to DRFs and partially unleashes the intramolecular autoinhibition of DRFs. However, whether proteins other than Rho involve the regulation of the actin assembly activity of DRFs has been unclear. Here, we show that Flightless-I (Fli-I), a gelsolin family protein essential for early development, binds directly to Daam1 and mDia1. Fli-I enhances the intrinsic actin assembly activity of Daam1 and mDia1 in vitro and is required for Daam1-induced actin assembly in living cells. Furthermore, Fli-I promotes the GTP-bound active Rho-mediated relief of the autoinhibition of Daam1 and mDia1. Thus, Fli-I is a novel positive regulator of Rho-induced linear actin assembly mediated by DRFs.
- Published
- 2010
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