title: Protein kinase Czeta mediates insulin-induced glucose transport through actin remodeling in L6 muscle cells.
abstract: Protein kinase C (PKC) zeta has been implicated in insulin-induced glucose uptake in skeletal muscle cell, although the underlying mechanism remains unknown. In this study, we investigated the effect of PKCzeta on actin remodeling and glucose transport in differentiated rat L6 muscle cells expressing myc-tagged glucose transporter 4 (GLUT4). On insulin stimulation, PKCzeta translocated from low-density microsomes to plasma membrane accompanied by increase in GLUT4 translocation and glucose uptake. Z-scan confocal microscopy revealed a spatial colocalization of relocated PKCzeta with the small GTPase Rac-1, actin, and GLUT4 after insulin stimulation. The insulin-mediated colocalization, PKCzeta distribution, GLUT4 translocation, and glucose uptake were inhibited by wortmannin and cell-permeable PKCzeta pseudosubstrate peptide. In stable transfected cells, overexpression of PKCzeta caused an insulin-like effect on actin remodeling accompanied by a 2.1-fold increase in GLUT4 translocation and 1.7-fold increase in glucose uptake in the absence of insulin. The effects of PKCzeta overexpression were abolished by cell-permeable PKCzeta pseudosubstrate peptide, but not wortmannin. Transient transfection of constitutively active Rac-1 recruited PKCzeta to new structures resembling actin remodeling, whereas dominant negative Rac-1 prevented the insulin-mediated PKCzeta translocation. Together, these results suggest that PKCzeta mediates insulin effect on glucose transport through actin remodeling in muscle cells.
authors.affiliation: Department of Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, 100005 Beijing, China.
authors.forename: Li-Zhong
authors.initials: LZ
authors.lastname: Liu
authors.forename: Hai-Lu
authors.initials: HL
authors.lastname: Zhao
authors.forename: Jin
authors.initials: J
authors.lastname: Zuo
authors.forename: Stanley K S
authors.initials: SK
authors.lastname: Ho
authors.forename: Juliana C N
authors.initials: JC
authors.lastname: Chan
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Fu-De
authors.initials: FD
authors.lastname: Fang
authors.forename: Peter C Y
authors.initials: PC
authors.lastname: Tong
mesh_terms: D000199:Actins / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D020559:Monomeric GTP-Binding Proteins / Q000032:analysis / Q000378:metabolism; D032342:Muscle Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D020830:rac1 GTP-Binding Protein / Q000032:analysis / Q000378:metabolism; D000099221:Protein Kinase C zeta
chemical_list: D000199:Actins; D005947:Glucose; D051275:Glucose Transporter Type 4; D007328:Insulin; D020559:Monomeric GTP-Binding Proteins; D011493:Protein Kinase C; D020830:rac1 GTP-Binding Protein; D000099221:Protein Kinase C zeta; C495694:Slc2a4 protein, rat