1998 Fiscal Year Final Research Report Summary
Extracellular matrix in liver cirrhosis : its abnormality and influence on liver functions.
| Project/Area Number |
09670512
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Gastroenterology
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| Research Institution | University of Tokyo |
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Principal Investigator |
OGATA Itsuro Univ.of Tokyo, fac. of Med., Assistant Professor, 医学部・附属病院, 助手 (80169169)
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| Co-Investigator(Kenkyū-buntansha) |
YANASE Mikio Univ.of Tokyo, fac. of Med., Senior Resident, 医学部・附属病院, 医員
TOMIYA Tomoaki Univ.of Tokyo, fac. of Med., Assistant Professor, 医学部・附属病院, 助手 (90227637)
IKEDA Hitoshi Univ.of Tokyo, fac. of Med., Assistant Professor, 医学部・附属病院, 助手 (80202422)
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| Project Period (FY) |
1997 – 1998
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| Keywords | extracellular matrix / Rho-kinase / cirrgotic liver / phospholylation / Hepatic stellate cell / Rho |
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| Research Abstract |
In cirrhotic liver, abundant extracellular matrices and deranged lobular architecture deteriorate the organ-specific function. Hepatic stellate cells (HSCs) transform into myofibroblast-like cells and play an important role in the hepatic fibrogenesis by producing an excess amount of extracellular matrix proteins and contracting the healing wound. We have cloned a serine/threonine protein kinase from a cDNA library prepared from HSC line derived from a CCI_4 induced cirrhotic rat liver. It is identical to the recently-reported Rho-kinase, one of Rho effectors, through which several actomyosin-based cellular processes such as adhesion, cytokinesis, and contraction are regulatcd. This study mainly aimed to clarify the functions of Rho and Rho-kinase in HSCs.
Immunoblot analysis confirmed the protein expression and auto-phosphorylation of Rho-kinase by HSCs, as well as their regulation by Rho-stimulator lysophosphatidic acid (LPA). Contraction assay using type I collagen lattice showed that LPA induced contraction of HSCs in a dose-dependent manner, and its effect was reduced by the addition of C3 exoenzyme, an inactivator of Rho. Protein expression of alpha-smooth muscle actin, a cytoskeletal protein in activated HSCs, was not affected by addition of LPA or C3 exoenzyme. When HSCs were added with fibronectin-coated beads, the subplasmalemmal assembly of focal adhesion complex and related proteins including Rho and Rho-kinase were observed arround the beads, and C3 exoenzyme abrogated the assembly.
From these data, Rho and Rho-kinase might be involved in the intracellular transduction of the signal from extracellular matrices in HSCs.
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