Alpha-actinin associates with polycystin-2 and regulates its channel activity

Hum Mol Genet. 2005 Jun 15;14(12):1587-603. doi: 10.1093/hmg/ddi167. Epub 2005 Apr 20.


Polycystin-2 (PC2) is the product of the PKD2 gene, which is mutated in 10-15% patients of autosomal dominant polycystic kidney disease (ADPKD). PC2 is an integral transmembrane protein and acts as a calcium-permeable cation channel. The functional modulation of this channel by other protein partners remains largely unknown. In the present study, using a yeast two-hybrid approach, we discovered that both intracellular N- and C-termini of PC2 associate with alpha-actinins, actin-binding and actin-bundling proteins important in cytoskeleton organization, cell adhesion, proliferation and migration. The PC2-alpha-actinin association was confirmed by in vitro glutathione S-transferase pull-down and dot blot overlay assays. In addition, the in vivo interaction between endogenous PC2 and alpha-actinins was demonstrated by co-immunoprecipitation in human embryonic kidney 293 and Madin-Darby canine kidney (MDCK) cells, rat kidney and heart tissues and human syncytiotrophoblast (hST) apical membrane vesicles. Immunofluorescence experiments showed that PC2 and alpha-actinin were partially co-localized in epithelial MDCK and inner medullary collecting duct cells, NIH 3T3 fibroblasts and hST vesicles. We studied the functional modulation of PC2 by alpha-actinin in a lipid bilayer electrophysiology system using in vitro translated PC2 and found that alpha-actinin substantially stimulated the channel activity of reconstituted PC2. A similar stimulatory effect of alpha-actinin on PC2 was also observed when hST vesicles were reconstituted in lipid bilayer. Thus, physical and functional interactions between PC2 and alpha-actinin may play an important role in abnormal cell adhesion, proliferation and migration observed in ADPKD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinin / metabolism*
  • Actins / metabolism*
  • Animals
  • Biotinylation
  • Calcium Channels / metabolism*
  • Cells, Cultured
  • Glutathione Transferase / genetics
  • Glutathione Transferase / metabolism
  • Humans
  • Immunoprecipitation
  • Kidney / metabolism
  • Lipid Bilayers
  • Membrane Proteins / metabolism*
  • Mice
  • Polycystic Kidney, Autosomal Dominant / metabolism
  • Protein Transport
  • Saccharomyces cerevisiae / genetics
  • Subcellular Fractions
  • TRPP Cation Channels
  • Two-Hybrid System Techniques


  • Actins
  • Calcium Channels
  • Lipid Bilayers
  • Membrane Proteins
  • TRPP Cation Channels
  • polycystic kidney disease 2 protein
  • Actinin
  • Glutathione Transferase