A novel regulatory mechanism of myosin light chain phosphorylation via binding of 14-3-3 to myosin phosphatase.
Myosin II phosphorylation-dependent cell motile events are regulated by myosin light-chain (MLC) kinase and MLC phosphatase (MLCP). Recent studies have revealed myosin phosphatase targeting subunit (MYPT1), a myosin-binding subunit of MLCP, plays a critical role in MLCP regulation. Here we report the new regulatory mechanism of MLCP via the interaction between 14-3-3 and MYPT1. The binding of 14-3-3beta to MYPT1 diminished the direct binding between MYPT1 and myosin II, and 14-3-3beta overexpression abolished MYPT1 localization at stress fiber. Furthermore, 14-3-3beta inhibited MLCP holoenzyme activity via the interaction with MYPT1. Consistently, 14-3-3beta overexpression increased myosin II phosphorylation in cells. We found that MYPT1 phosphorylation at Ser472 was critical for the binding to 14-3-3. Epidermal growth factor (EGF) stimulation increased both Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase inhibitor inhibited the EGF-induced Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase specific siRNA also decreased EGF-induced Ser472 phosphorylation correlated with the decrease in MLC phosphorylation. The present study revealed a new RhoA/Rho-kinase-dependent regulatory mechanism of myosin II phosphorylation by 14-3-3 that dissociates MLCP from myosin II and attenuates MLCP activity.
Koga
Yasuhiko
Y
Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
Ikebe
Mitsuo
M
D048948:14-3-3 Proteins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006801:Humans; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D018994:Myosin Light Chains / Q000378:metabolism*; D024462:Myosin Type II / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism*; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D054645:Protein Phosphatase 1 / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D022502:Stress Fibers / Q000201:enzymology; D020798:Two-Hybrid System Techniques
D048948:14-3-3 Proteins; D018994:Myosin Light Chains; C482982:YWHAB protein, human; D010768:Phosphoserine; C499850:Ppp1r12a protein, rat; D054645:Protein Phosphatase 1; D043263:Myosin-Light-Chain Phosphatase; D024462:Myosin Type II