title: Interaction of cofilin with triose-phosphate isomerase contributes glycolytic fuel for Na,K-ATPase via Rho-mediated signaling pathway.
abstract: We reported previously that cofilin, an actin-binding protein, interacts with Na,K-ATPase and enhances its activity (Lee, K., Jung, J., Kim, M., and Guidotti, G. (2001) Biochem. J. 353, 377-385). To understand the nature of this interaction and the role of cofilin in the regulation of Na,K-ATPase activity, we searched for cofilin-binding proteins in the rat skeletal muscle cDNA library using the yeast two-hybrid system. Several cDNA clones were isolated, some of which coded for triose-phosphate isomerase, a glycolytic enzyme. The interaction of cofilin with triose-phosphate isomerase as well as Na,K-ATPase was confirmed by immunoprecipitation and confocal microscopy in HeLa cells. Cofilin was translocated to the plasma membrane along with triose-phosphate isomerase by the Rho activator lysophosphatidic acid but not by the p160 Rho-associated kinase inhibitor Y-27632, suggesting that the phosphorylated form of cofilin bound to TPI interacts with Na,K-ATPase. Ouabain-sensitive (86)Rb(+) uptake showed that Na,K-ATPase activity was increased by the overexpression of cofilin and lysophosphatidic acid treatment, but not by the overexpression of mutant cofilin S3A and Y-27632 treatment. Pretreatment with the glycolytic inhibitor iodoacetic acid caused a remarkable reduction of Na,K-ATPase activity, whereas pretreatment with the oxidative inhibitor carbonyl cyanide m-chlorophenylhydrazone caused no detectable changes, suggesting that the phosphorylated cofilin is involved in feeding glycolytic fuel for Na,K-ATPase activity. These findings provide a novel molecular mechanism for the regulation of Na,K-ATPase activity and for the nature of the functional coupling of cellular energy transduction.
mesh_terms: D051339:Actin Depolymerizing Factors; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D017931:DNA Primers; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006019:Glycolysis; D006367:HeLa Cells; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D051381:Rats; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014305:Triose-Phosphate Isomerase / Q000378:metabolism*
chemical_list: D051339:Actin Depolymerizing Factors; D017931:DNA Primers; D008840:Microfilament Proteins; D019204:GTP-Binding Proteins; D014305:Triose-Phosphate Isomerase; D000254:Sodium-Potassium-Exchanging ATPase