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Members of the CIP4 family of proteins participate in the regulation of platelet‐derived growth factor receptor‐β‐dependent actin reorganization and migration
Author(s) -
Toguchi Marcia,
Richnau Ninna,
Ruusala Aino,
Aspenström Pontus
Publication year - 2010
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1042/bc20090033
Subject(s) - cdc42 , biology , microbiology and biotechnology , formins , platelet derived growth factor receptor , endocytosis , internalization , growth factor , actin , receptor , cell , actin cytoskeleton , biochemistry , cytoskeleton
Background information . The F‐BAR {Fes/CIP4 [Cdc42 (cell division cycle 42)‐interacting protein 4] homology and BAR (Bin/amphiphysin/Rvs)} proteins have emerged as important co‐ordinators of signalling pathways that regulate actin assembly and membrane dynamics. The presence of the F‐BAR domain is the hallmark of this family of proteins and the CIP4 (Cdc42‐interacting protein 4) was one of the first identified vertebrate F‐BAR proteins. There are three human CIP4 paralogues, namely CIP4, FBP17 (formin‐binding protein 17) and Toca‐1 (transducer of Cdc42‐dependent actin assembly 1). The CIP4‐like proteins have been implicated in Cdc42‐dependent actin reorganization and in regulation of membrane deformation events visible as tubulation of lipid bilayers. Results . We performed side‐by‐side analyses of the three CIP4 paralogues. We found that the three CIP4‐like proteins vary in their effectiveness to catalyse membrane tubulation and actin reorganization. Moreover, we show that the CIP4‐dependent membrane tubulation is enhanced in the presence of activated Cdc42. Some F‐BAR members have been shown to have a role in the endocytosis of the EGF (epidermal growth factor) receptor and this prompted us to study the involvement of the CIP4‐like proteins in signalling of the PDGFRβ [PDGF (platelet‐derived growth factor) β‐receptor]. We found that knock‐down of CIP4‐like proteins resulted in a prolonged formation of PDGF‐induced dorsal ruffles, as well as an increased PDGF‐dependent cell migration. This was most likely a consequence of a sustained PDGFRβ activation caused by delayed internalization of the receptor in the cells treated with siRNA (small interfering RNA) specific for the CIP4‐like proteins. Conclusions . Our findings show that CIP4‐like proteins induced membrane tubulation downstream of Cdc42 and that they have important roles in PDGF‐dependent actin reorganization and cell migration by regulating internalization and activity of the PDGFRβ. Moreover, the results suggest an important role for the CIP4‐like proteins in the regulation of the activity of the PDGFRβ.