CaMKII-mediated phosphorylation of the myosin motor Myo1c is required for insulin-stimulated GLUT4 translocation in adipocytes

TY - JOUR

T1 - CaMKII-mediated phosphorylation of the myosin motor Myo1c is required for insulin-stimulated GLUT4 translocation in adipocytes

AU - Yip, Ming Fai

AU - Ramm, Georg

AU - Larance, Mark

AU - Hoehn, Kyle L.

AU - Wagner, Mark C.

AU - Guilhaus, Michael

AU - James, David E.

PY - 2008/11/5

Y1 - 2008/11/5

N2 - The unconventional myosin Myo1c has been implicated in insulin-regulated GLUT4 translocation to the plasma membrane in adipocytes. We show that Myo1c undergoes insulin-dependent phosphorylation at S701. Phosphorylation was accompanied by enhanced 14-3-3 binding and reduced calmodulin binding. Recombinant CaMKII phosphorylated Myo1c in vitro and siRNA knockdown of CaMKIIdelta abolished insulin-dependent Myo1c phosphorylation in vivo. CaMKII activity was increased upon insulin treatment and the CaMKII inhibitors CN21 and KN-62 or the Ca(2+) chelator BAPTA-AM blocked insulin-dependent Myo1c phosphorylation and insulin-stimulated glucose transport in adipocytes. Myo1c ATPase activity was increased after CaMKII phosphorylation in vitro and after insulin stimulation of CHO/IR/IRS-1 cells. Expression of wild-type Myo1c, but not S701A or ATPase dead mutant K111A, rescued the inhibition of GLUT4 translocation by siRNA-mediated Myo1c knockdown. These data suggest that insulin regulates Myo1c function via CaMKII-dependent phosphorylation, and these events play a role in insulin-regulated GLUT4 trafficking in adipocytes likely involving Myo1c motor activity.

AB - The unconventional myosin Myo1c has been implicated in insulin-regulated GLUT4 translocation to the plasma membrane in adipocytes. We show that Myo1c undergoes insulin-dependent phosphorylation at S701. Phosphorylation was accompanied by enhanced 14-3-3 binding and reduced calmodulin binding. Recombinant CaMKII phosphorylated Myo1c in vitro and siRNA knockdown of CaMKIIdelta abolished insulin-dependent Myo1c phosphorylation in vivo. CaMKII activity was increased upon insulin treatment and the CaMKII inhibitors CN21 and KN-62 or the Ca(2+) chelator BAPTA-AM blocked insulin-dependent Myo1c phosphorylation and insulin-stimulated glucose transport in adipocytes. Myo1c ATPase activity was increased after CaMKII phosphorylation in vitro and after insulin stimulation of CHO/IR/IRS-1 cells. Expression of wild-type Myo1c, but not S701A or ATPase dead mutant K111A, rescued the inhibition of GLUT4 translocation by siRNA-mediated Myo1c knockdown. These data suggest that insulin regulates Myo1c function via CaMKII-dependent phosphorylation, and these events play a role in insulin-regulated GLUT4 trafficking in adipocytes likely involving Myo1c motor activity.

KW - Animals

KW - 14-3-3 Proteins

KW - 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine

KW - Myosins

KW - Mice

KW - Glucose Transporter Type 4

KW - Insulin

KW - Calcium-Calmodulin-Dependent Protein Kinase Type 2

KW - Myosin Type I

KW - Phosphorylation

KW - Adipocytes

KW - Cell Line

KW - Protein Transport

KW - Cricetinae

U2 - 10.1016/j.cmet.2008.09.011

DO - 10.1016/j.cmet.2008.09.011

M3 - Article

C2 - 19046570

SN - 1932-7420

VL - 8

SP - 384

EP - 398

JO - Cell Metabolism

JF - Cell Metabolism

IS - 5

ER -