TI - High glucose increases phosphocofilin via phosphorylation of LIM kinase due to Rho/Rho kinase activation in cultured pig proximal tubular epithelial cells . AB - In proximal tubular epithelial cells ( PTECs ) , depolymerization of actin by cofilin plays a crucial role in maintaining polarity and function . Cofilin is inactivated when phosphorylated by p-Lin-11/Isl-1/Mec-3 kinase ( LIMK ) to give p-cofilin . LIMK is phosphorylated by phosphorylated p21-activated kinase ( PAK ) , a downstream signal of phosphoinositide 3-kinase ( PI3K ) , or by Rho kinase ( ROCK ) , and is dephosphorylated by slingshot ( SSH ) . However , in PTECs the signaling pathways regulating phosphorylation and dephosphorylation of cofilin , and the influence of high glucose ( HG ) on these pathways remain to be elucidated . Here , we show that HG in cultured porcine PTECs (LLC-PK1) increases p-cofilin and p-LIMK1 beyond 6h and that the simultaneous presence of phlorizin reverses the increase . HG did not influence the levels of PI3K-p85 , downstream signals to SSH1 and p-PAK1 , and mRNA of cofilin , LIMK1 and SSH1 . On the other hand , wortmannin and LY294002 markedly increased p-cofilin and p-LIMK1 without influencing on the level of SSH1 protein . HG -activated RhoA and ROCK2 beyond 3h , and phlorizin attenuated this activation . GF109203X inhibited HG -induced increase in membranous RhoA and ROCK2 , and phorbol ester increased these proteins . Y27632 ( a ROCK inhibitor ) reversed HG -induced increases of p-cofilin and p-LIMK1 . We conclude that HG increases p-cofilin by phosphorylating LIMK1 through activation of Rho/Rho kinase , probably due to diacylglycerol-sensitive PKC activation resulting from increased glucose influx . HG did not alter PI3K or its downstream signals , even though PI3K has a physiological role in maintaining the cofilin level by activating SSH1 .