2001 Fiscal Year Final Research Report Summary
Molecular and cellular physiological studies on the intracellular signal transduction causing abnormal vascular contraction
| Project/Area Number |
11470012
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | Yamaguchi University |
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Principal Investigator |
KOBAYASHI Sei Yamaguchi University, School of Medicine, Professor, 医学部, 教授 (80225515)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUKAMI Yoichi Yamaguchi University, School of Medicine, Associate Professor, 医学部, 助教授 (80274158)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Signal Transduction / Cytosolic Calcium Ion / Vascular Smooth Muscle / Rho-kinase / Ca2 + -independent contraction |
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| Research Abstract |
The following results were obtained : 1. FIRST YEAR : We performed the screening for on the signal molecule(s) which may mediate signal transduction from the cell membrane to cytosolic messenger, Rho-kinase. We identified a sphingolipid, sphingosylphosphorylcholine (SPC) as a novel messenger for the Ca2 + -independent contraction of vascular smooth muscle (VSM) mediated by Ryo-kinase. In addition, we found that SPC induces Ca2 + -independent contraction in the absence of cytosolic GTP in permeabilized VSM strips, which was blocked by a Rho-kinase inhibitor, suggesting that sphingolipid-induced contraction is mediated by Rho-kinase, Fluorometry of fura-2 revealed that sphingolipids induced large contraction without elevation of cytosolic Ca2 + concentration ([Ca2 +]i) in cerebral arteries, supporting the role of sphingolipid as a mediator for the Ca2 + -independent contraction.
2. SECOND YEAR : In order to confirm the involvement of Rho-kinase in the SPC-induced Ca2 + -independent contra
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ction of VSM, dominant negative Rho-kinase was introduced into the cytosol of the peremeabilized VSM strips, and it completely abolished the Ca2 + -independent contraction induced by SPC. In addition, pseudosubstrate peptide of conventional and novel protein kinase C (PKC) had no effect on the SPC-induced contraction , whereas it abolished the Ca2 + -independent contraction induced by a PKC activator, phorbol ester. These results indicate that SPC induces Ca2 + -independent contraction of VSM which is mediated by Rho-kinase, but not by PKC.
3. THIRD YEAR : We started to investigate the Ca2 + -independent contraction of human and mammalian VSM strips. Sphingolipid induced very small contraction obtained from patients or rabbit whose cholesterol levels are normal, but induced large contraction of the strips obtained from patients or rabbit whose cholesterol levels are high. In addition, the SPC-induced contraction depended on the tissue content of cholesterol in VSM. These finding suggest that a sphingoliopid/Rho-kinase pathway plays an important role in the development of abnormal VSM contraction which was frequently associated with hyperlipidemia. Less
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