Structural interaction and functional regulation of polycystin-2 by filamin.
Filamins are important actin cross-linking proteins implicated in scaffolding, membrane stabilization and signal transduction, through interaction with ion channels, receptors and signaling proteins. Here we report the physical and functional interaction between filamins and polycystin-2, a TRP-type cation channel mutated in 10-15% patients with autosomal dominant polycystic kidney disease. Yeast two-hybrid and GST pull-down experiments demonstrated that the C-termini of filamin isoforms A, B and C directly bind to both the intracellular N- and C-termini of polycystin-2. Reciprocal co-immunoprecipitation experiments showed that endogenous polycystin-2 and filamins are in the same complexes in renal epithelial cells and human melanoma A7 cells. We then examined the effect of filamin on polycystin-2 channel function by electrophysiology studies with a lipid bilayer reconstitution system and found that filamin-A substantially inhibits polycystin-2 channel activity. Our study indicates that filamins are important regulators of polycystin-2 channel function, and further links actin cytoskeletal dynamics to the regulation of this channel protein.
Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
Qian
Q
Wang
Xiao-Qing
XQ
Dai
Qiang
Q
Li
Zuocheng
Z
Wang
María del Rocío
Mdel R
Cantero
Shu
S
Li
Ji
J
Shen
Jian-Cheng
JC
Tu
Horacio
H
Cantiello
Xing-Zhen
XZ
Chen
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D003285:Contractile Proteins / Q000737:chemistry* / Q000502:physiology; D064448:Filamins; D006801:Humans; D047468:Immunoprecipitation; D008051:Lipid Bilayers; D008840:Microfilament Proteins / Q000737:chemistry* / Q000502:physiology; D020033:Protein Isoforms / Q000378:metabolism; D050396:TRPP Cation Channels / Q000502:physiology*; D020798:Two-Hybrid System Techniques
D015220:Calcium Channels; D003285:Contractile Proteins; D064448:Filamins; D008051:Lipid Bilayers; D008840:Microfilament Proteins; D020033:Protein Isoforms; D050396:TRPP Cation Channels