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179 results on '"Ishikawa, Ryoki"'

7. Stimulatory effects of arachidonic acid on myosin ATPase activity and contraction of smooth muscle via myosin motor domain

Author

Katayama, Takeshi, Watanabe, Masaru, Tanaka, Hideyuki, Hino, Mizuki, Miyakawa, Takuya, Ohki, Takashi, Ye, Li-Hong, Xie, Ce, Yoshiyama, Shinji, Nakamura, Akio, Ishikawa, Ryoki, Tanokura, Masaru, Oiwa, Kazuhiro, and Kohama, Kazuhiro

Subjects
Arachidonic acid -- Research, Arachidonic acid -- Physiological aspects, Muscle contraction -- Research, Adenosine triphosphatase -- Physiological aspects, Adenosine triphosphatase -- Research, Biological sciences
Abstract

We have been searching for a mechanism to induce smooth muscle contraction that is not associated with phosphorylation of the regulatory light chain (RLC) of smooth muscle myosin (Nakamura A, Xie C, Zhang Y, Gao Y, Wang HH, Ye LH, Kishi H, Okagaki T, Yoshiyama S, Hayakawa K, Ishikawa R, Kohama K. Biochem Biophys Res Commun 369: 135-143, 2008). In this article, we report that arachidonic acid (AA) stimulates ATPase activity of unphosphorylated smooth muscle myosin with maximal stimulation ([R.sub.max]) of 6.84 [+ or -] 0.51 relative to stimulation by the vehicle and with a half-maximal effective concentration ([EC.sub.50]) of 50.3 [+ or -] 4.2 [micro]M. In the presence of actin, [R.sub.max] was 1.72 [+ or -] 0.08 and [EC.sub.50] was 26.3 -+ 2.3 [micro]M. Our experiments with eicosanoids consisting of the AA cascade suggested that they neither stimulated nor inhibited the activity. Under conditions that did not allow RLC to be phosphorylated, AA stimulated contraction of smooth muscle tissue with an [R.sub.max] of 1.45 [+ or -] 0.07 and an [EC.sub.50] of 27.0 +- 4.4 ~M. In addition to the ATPase activities of the myosin, AA stimulated those of heavy meromyosin, subfragment 1 (S 1), S 1 from which the RLC was removed, and a recombinant heavy chain consisting of the myosin head. The stimulatory effects of AA on these preparations were about twofold. The site of AA action was indicated to be the step-releasing inorganic phosphate (P0 from the reaction intermediate of the myosin-ADP-[P.sub.i] complex. The enhancement of [P.sub.i] release by AA was supported by computer simulation indicating that AA docked in the actin-binding cleft of the myosin motor domain. The stimulatory effect of AA was detectable with both unphosphorylated myosin and the myosin in which RLC was fully phosphorylated. The AA effect on both myosin forms was suggested to cause excess contraction such as vasospasm. skinned fiber doi: 10.1152/ajpheart.00577.2009

Published
2010

8. Nonkinase activity of MLCK in elongated filopodia formation and chemotaxis of vascular smooth muscle cells toward sphingosylphosphorylcholine

Author

Wang, Hong Hui, Nakamura, Akio, Matsumoto, Atsushi, Yoshiyama, Shinji, Qin, Xiaoran, Ye, Li-Hong, Xie, Ce, Zhang, Yue, Gao, Ying, Ishikawa, Ryoki, and Kohama, Kazuhiro

Subjects
Muscle cells -- Physiological aspects, Muscle cells -- Research, Protein kinases -- Physiological aspects, Protein kinases -- Research, Actin -- Physiological aspects, Actin -- Research, Myosin -- Physiological aspects, Myosin -- Research, Biological sciences
Abstract

The actin-myosin interaction of vascular smooth muscle cells (VSMCs) is regulated by myosin light chain kinase (MLCK), which is a fusion protein of the central catalytic domain with the N-terminal actin-binding and C-terminal myosin-binding domains. In addition to the regulatory role of kinase activity mediated by the catalytic domain, nonkinase activity that derives from both terminals is able to exert a regulatory role as reviewed by Nakamura et al. (32). We previously showed that nonkinase activity mediated the filopodia upon the stimulation by sphingosylphosphorylcholine (SPC) (25). To explore the regulatory role of nonkinase activity in chemotaxis, we constructed VSMCs where the expression of MLCK was totally abolished by using a lentivirus-mediated RNAi system. We hypothesized that the MLCK-downregulated VSMCs were unable to form filopodia and to migrate upon SPC stimulation and confirmed the hypothesis. We further constructed a kinase-inactive mutant from bovine cDNA coding wild-type (WT) MLCK by mutating the ATP-binding sites located in the catalytic domain, followed by confirming the presence (absence) of the kinase activity of WT (kinase-inactive mutant). We transfected WT and the mutant into MLCK-downregulated VSMCs. We expected that the transfected VSMCs will recover the ability to induce filopodia and chemotaxis toward SPC and found both constructs rescued the ability. Because they share the actin- and myosin-binding domains, we concluded nonkinase activity plays a major role for SPC-induced migration. chemotaxis; myosin light chain kinase

Published
2009

9. Blebbistatin inhibits the chemotaxis of vascular smooth muscle cells by disrupting the myosin II-actin interaction

Author

Wang, Hong Hui, Tanaka, Hideyuki, Qin, Xiaoran, Zhao, Tiejun, Ye, Li-Hong, Okagaki, Tuyoshi, Katayama, Takeshi, Nakamura, Akio, Ishikawa, Ryoki, Thatcher, Sean E., Wright, Gary L., and Kohama, Kazuhiro

Subjects
Cell membranes -- Properties, Chemotaxis -- Evaluation, Vascular smooth muscle -- Medical examination, Muscle cells -- Properties, Myosin -- Properties, Biological sciences
Abstract

Blebbistatin is a myosin II-specific inhibitor. However, the mechanism and tissue specificity of the drug are not well understood. Blebbistatin blocked the chemotaxis of vascular smooth muscle cells (VSMCs) toward sphingosylphosphorylcholine (I[C.sub.50] = 26.1 [+ or -] 0.2 and 27.5 [+ or -] 0.5 [micro]M for GbaSM-4 and A7r5 cells, respectively) and platelet-derived growth factor BB (I[C.sub.50] = 32.3 [+ or -] 0.9 and 31.6 [+ or -] 1.3 [micro]M for GbaSM-4 and A7r5 cells, respectively) at similar concentrations. Immunofluorescence and fluorescent resonance energy transfer analysis indicated a blebbistatin-induced disruption of the actin-myosin interaction in VSMCs. Subsequent experiments indicated that blebbistatin inhibited the [Mg.sup.2+]-ATPase activity of the unphosphorylated (I[C.sub.50] = 12.6 [+ or -] 1.6 and 4.3 [+ or -] 0.5 [micro]M for gizzard and bovine stomach, respectively) and phosphorylated (I[C.sub.50] = 15.0 [+ or -] 0.6 [micro]M for gizzard) forms of purified smooth muscle myosin II, suggesting a direct effect on myosin II motor activity. It was further observed that the [Mg.sup.2+]-ATPase activities of gizzard myosin II fragments, heavy meromyosin (I[C.sub.50] = 14.4 [+ or -] 1.6 [micro]M) and subfragment 1 (I[C.sub.50] = 5.5 [+ or -] 0.4 [micro]M), were also inhibited by blebbistatin. Assay by in vitro motility indicated that the inhibitory effect of blebbistatin was reversible. Electron-microscopic evaluation showed that blebbistatin induced a distinct conformational change (i.e., swelling) of the myosin II head. The results suggest that the site of blebbistatin action is within the S1 portion of smooth muscle myosin II. Boyden chamber; fluorescence resonance energy transfer; ATPase; in vitro motility assay; electron microscopy

Published
2008

14. Mitosis-specific phosphorylation causes 83K non-muscle caldesmon to dissociate from microfilaments

Author

Yamashiro, Shigeki, Yamakita, Yoshihiko, Ishikawa, Ryoki, and Matsumura, Fumio

Subjects
Biochemistry -- Research, Mitosis -- Research, Proteins -- Physiological aspects, Cytoplasmic filaments -- Physiological aspects, Eukaryotic cells -- Growth, Phosphorylation -- Physiological aspects, Environmental issues, Science and technology, Zoology and wildlife conservation
Published
1990

31. 1P306 Drebrin-A, a spine specific actin-binding protein in neurons, inhibits the activities of ADF/cofilin, caldesmon, and myosin-V(10. Cytoskeleton,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

Author

Ishikawa, Ryoki, primary, Katoh, Kaoru, additional, Takahashi, Ayumi, additional, Xie, Ce, additional, Oseki, Koushi, additional, Watanabe, Michitoshi, additional, Igarashi, Michihiro, additional, Nakamura, Akio, additional, and Kohama, Kazuhiro, additional

Published
2006
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32. Myosin-Va Regulates Exocytosis through the Submicromolar Ca2+-dependent Binding of Syntaxin-1A

Author

Watanabe, Michitoshi, primary, Nomura, Kazushige, additional, Ohyama, Akihiro, additional, Ishikawa, Ryoki, additional, Komiya, Yoshiaki, additional, Hosaka, Kohei, additional, Yamauchi, Emiko, additional, Taniguchi, Hisaaki, additional, Sasakawa, Nobuyuki, additional, Kumakura, Konosuke, additional, Ushiki, Tatsuo, additional, Sato, Osamu, additional, Ikebe, Mitsuo, additional, and Igarashi, Michihiro, additional

Published
2005
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40. Stable transformants of smooth muscle cell line lacking myosin light chain kinase, and their characterization with respect to actomyosin system

Author

Kishi, Hiroko, primary, Mikawa, Takashi, additional, Seto, Minoru, additional, Sasaki, Yasuharu, additional, Kanayasu-Toyoda, Toshie, additional, Yamaguchi, Teruhide, additional, Imamura, Michihiro, additional, Itoh, Masaaki, additional, Nakamura, Akio, additional, Ishikawa, Ryoki, additional, and Kohama, Kazuhiro, additional

Published
1998
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