Essential role of rho kinase in the ca2+ sensitization of prostaglandin F2α-induced contraction of rabbit aortae
| Autor: | Minoru Seto, Yoh Takuwa, Hiromitsu Nagumo, Kazutoshi Shindo, Junji Nakamura, Katsuaki Ito, Erika Shimomura, Mitsuya Shiraishi, Takahiro Iwanaga, Yasuharu Sasaki |
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| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: |
medicine.medical_specialty
Myosin light-chain kinase Indoles Myosin Light Chains Physiology Vasodilator Agents macromolecular substances In Vitro Techniques Protein Serine-Threonine Kinases Dinoprost Dephosphorylation Myosin-Light-Chain Phosphatase Internal medicine 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine medicine Phosphoprotein Phosphatases Animals Vasoconstrictor Agents Enzyme Inhibitors Phosphorylation Rho-associated protein kinase Protein kinase C Aorta Protein Kinase C rho-Associated Kinases Chemistry Kinase Fasudil Intracellular Signaling Peptides and Proteins Original Articles Azepines Cell biology Isoenzymes Molecular Weight Endocrinology Vasoconstriction Calcium Rabbits Vascular smooth muscle contraction |
| Popis: | Inhibition of dephosphorylation of the 20 kDa myosin light chain (MLC(20)) is an important mechanism for the Ca(2+)-induced sensitization of vascular smooth muscle contraction. We investigated whether this mechanism operates in prostaglandin F(2alpha) (PGF(2alpha))-induced contraction of rabbit aortic smooth muscle and, if so, whether protein kinase C (PKC) or rho-associated kinase (rho kinase) contribute to the inhibition of dephosphorylation. In normal medium, PGF(2alpha) (10 microM) increased the phosphorylation of MLC(20) and developed tension. The rho-kinase inhibitors fasudil and hydroxyfasudil inhibited these changes, despite having no effect on a phorbol-ester-induced MLC(20) phosphorylation. After treatment with verapamil or chelation of external Ca(2+) with EGTA, PGF(2alpha) increased the MLC(20) phosphorylation and tension without an increase in [Ca(2+)](i), all of which were sensitive to fasudil and hydroxyfasudil. ML-9, a MLC kinase inhibitor, quickly reversed the KCl-induced MLC(20) phosphorylation and contraction to the resting level. However, fractions of PGF(2alpha)-induced contraction and MLC(20) phosphorylation were resistant to ML-9 but were sensitive to fasudil. Ro31-8220 (10 microM), a PKC inhibitor, did not affect the phosphorylation of MLC(20) and the tension caused by PGF(2alpha), thus excluding the possibility of the involvement of PKC in the PGF(2alpha)-induced MLC(20) phosphorylation. PGF(2alpha) increased phosphorylation at Thr654 of the myosin binding subunit (MBS) of myosin phosphatase, which is a target of rho kinase, and fasudil decreased the phosphorylation. These data suggest that the PGF(2alpha)-induced contraction is accompanied by the inhibition of MLC(20) dephosphorylation through rho kinase-induced MBS phosphorylation, leading to Ca(2+) sensitization of contraction. An actin-associated mechanism may also be involved in the PGF(2alpha)-induced sensitization. |
| Databáze: | OpenAIRE |
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