| Project/Area Number |
03454116
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General anatomy (including Histology/Embryology)
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
SAKAI Masahiro (1992) Kyoto Univ., Anatomy, Instructor, 医学部, 助手 (40183363)
小川 和朗 (1991) 京都大学, 医学部, 教授 (20077556)
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| Co-Investigator(Kenkyū-buntansha) |
NODA Toru Kyoto Univ., Anatomy, Instructor, 医学部, 助手 (50156204)
FUJIMOTO Kazushi Kyoto Univ., Anatomy, Lecturer, 医学部, 講師 (50159125)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1991: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | Gap junctions / Protein kinase C / Phorbol ester / Hepatocytes / Freeze-fracture / Immunocytochemistry / Na-K-ATPase / ギャップ結果 / プロテインキナーゼC / 眼房水産生 / 免疫電顕細胞化学 / プロティンキナ-ゼC / ホルボ-ルエステル |
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| Research Abstract |
Agonists and/or antagonists of cAMP-dependent protein kinase, protein kinase C (PKC), calmodulin/Ca++-dependent protein kinase, and several tyrosine kinases modulate gap junctional communication in various cell systems. Takeda et al. (1987) have determined that a major liver gap junction protein, connexin 32, is phosphorylated in vitro by PKC. They also showed that the addition of phorbol ester (PMA), an activator of PKC, to intact hepatocytes rapidly increased connexin 32 phosphorylation at serine residues. In this project, we have demonstrated that the addition of PMA to intact hepatocytes leads to marked decreases in gap junction areas (within 20 min.) by freeze-fracture electron microscopy. Furthermore, immuno-localization of PKC by electron microscopy with two monoclonal antibodies against type 2 and type 3 PKCs showed that both epitopes are associated with the gap junctional membranes in PMA treated hepatocytes. Our results suggest that PMA induced phosphorylation of connexin 32 causes breakdown of the gap junction. In fact, we detected internalization of the gap junctional membrane and annular gap junctions, which is one sequential step in the breakdown of the gap junction, in PMA treated hepatocytes.
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