Abba promotes PDGF-mediated membrane ruffling through activation of the small GTPase Rac1.
Abba is a member of the I-BAR-domain protein family that is characterized by a convex-shaped membrane-binding motif. Overexpression of GFP-tagged Abba in murine fibroblasts potentiated PDGF-mediated formation of membrane ruffles and lamellipodia. Immunofluorescent microscopy and pull-down analysis revealed that GFP-Abba colocalized with an active form of Rac1 in the membrane ruffles and enhanced the Rac GTPase activity in response to PDGF stimulation. Further immunoprecipitation assays demonstrated that GFP-Abba bound to both wild-type and constitutively active Rac1 and that the binding to either of the Rac1 forms was significantly enhanced upon PDGF stimulation. On the other hand, an Abba mutant deficient in Rac1 binding failed to promote membrane ruffling and Rac1 activation in response to PDGF. However, the cells overexpressing a truncated mutant carrying the I-BAR domain alone displayed numerous filopodia-like microspikes in a manner independent of growth factors. Also, the Rac-binding activity of the mutant was not affected by PDGF treatment. Our data indicates that the interaction between full-length Abba and Rac1 is implicated in membrane deformation and subjected to a growth factor-mediated regulation through the C-terminal sequence.
Zheng
Datong
D
Second Hospital, The Second Clinical School, Nanjing Medical University, Jiangjiayuan 121, Nanjing, Jiangsu 210011, China.
Niu
Shuqiong
S
Yu
Dan
D
Zhan
Xiaoguo H
XH
Zeng
Xianchun
X
Cui
Bota
B
Chen
Yanping
Y
Yoon
Jennifer
J
Martin
Stuart S
SS
Lu
Xiang
X
Zhan
Xi
X
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins; D041681:NIH 3T3 Cells; D010982:Platelet-Derived Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
C553801:MTSS2 protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010982:Platelet-Derived Growth Factor; D020830:rac1 GTP-Binding Protein