TY - JOUR
T1 - Characterization and function of MYPT2, a target subunit of myosin phosphatase in heart
AU - Okamoto, Ryuji
AU - Kato, Takaaki
AU - Mizoguchi, Akira
AU - Takahashi, Nobuaki
AU - Nakakuki, Tetsuya
AU - Mizutani, Hideo
AU - Isaka, Naoki
AU - Imanaka-Yoshida, Kyoko
AU - Kaibuchi, Kozo
AU - Lu, Zhaojiang
AU - Mabuchi, Katsuhide
AU - Tao, Terenc
AU - Hartshorne, David J.
AU - Nakano, Takeshi
AU - Ito, Masaaki
N1 - Funding Information:
This work was supported in part by grants-in-aid for Scientific Research from the Ministry of Education, Science, Technology, Sports and Culture, Japan (to M.I.), and by Grant HL23615 (D.J.H.) and P01 AR41637 (T.T.) from the National Institute of Health. We also thank Dr. Hiroki Aoki and Dr. Nobuyuki Moriki for helpful comments.
PY - 2006/9
Y1 - 2006/9
N2 - Characterization of cardiac MYPT2 (an isoform of the smooth muscle phosphatase [MP] target subunit, MYPT1) is described. Several features of MYPT2 and MYPT1 were similar, including: a specific interaction with the catalytic subunit of type 1 phosphatase, δ isoform (PP1cδ); interaction of MYPT2 with the small heart-specific MP subunit; interaction of the C-terminal region of MYPT2 with the active form of RhoA; phosphorylation by Rho-kinase at an inhibitory site, Thr646 and thiophosphorylation at Thr646 inhibited activity of the MYPT2-PP1cδ complex. MYPT2 activated PP1cδ activity, using light chains from smooth and cardiac muscle, by reducing Km and increasing kcat. The extent of activation (kcat) was greater than for MYPT1 and could reflect distinct N-terminal sequences in the two MYPT isoforms. Adenovirus-mediated gene transfer of MYPT2 and PP1cδ reduced the phosphorylation level of cardiac light chains following stimulation with A23187. Overexpression of MYPT2 and PP1cδ blocked the angiotensin II-induced sarcomere organization in cultured cardiomyocytes. Electron microscopy indicated locations of MYPTs, at, or close to, the Z-line, the A band and mitochondria. Similarity of the two MYPT isoforms suggests common enzymatic mechanisms and regulation. Cardiac myosin is a substrate for the MYPT2 holoenzyme, but the Z-line location raises the possibility of other substrates.
AB - Characterization of cardiac MYPT2 (an isoform of the smooth muscle phosphatase [MP] target subunit, MYPT1) is described. Several features of MYPT2 and MYPT1 were similar, including: a specific interaction with the catalytic subunit of type 1 phosphatase, δ isoform (PP1cδ); interaction of MYPT2 with the small heart-specific MP subunit; interaction of the C-terminal region of MYPT2 with the active form of RhoA; phosphorylation by Rho-kinase at an inhibitory site, Thr646 and thiophosphorylation at Thr646 inhibited activity of the MYPT2-PP1cδ complex. MYPT2 activated PP1cδ activity, using light chains from smooth and cardiac muscle, by reducing Km and increasing kcat. The extent of activation (kcat) was greater than for MYPT1 and could reflect distinct N-terminal sequences in the two MYPT isoforms. Adenovirus-mediated gene transfer of MYPT2 and PP1cδ reduced the phosphorylation level of cardiac light chains following stimulation with A23187. Overexpression of MYPT2 and PP1cδ blocked the angiotensin II-induced sarcomere organization in cultured cardiomyocytes. Electron microscopy indicated locations of MYPTs, at, or close to, the Z-line, the A band and mitochondria. Similarity of the two MYPT isoforms suggests common enzymatic mechanisms and regulation. Cardiac myosin is a substrate for the MYPT2 holoenzyme, but the Z-line location raises the possibility of other substrates.
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U2 - 10.1016/j.cellsig.2005.11.001
DO - 10.1016/j.cellsig.2005.11.001
M3 - Article
C2 - 16431080
AN - SCOPUS:33744794364
VL - 18
SP - 1408
EP - 1416
JO - Cellular Signalling
JF - Cellular Signalling
SN - 0898-6568
IS - 9
ER -