2000 Fiscal Year Final Research Report Summary
Involvement of Chemokines and vasoactive peptides in pressure-induced mesangial cells proliferation-Study with monocyte chemoattractant peptide (MCP)-1 and adrenomedullin-
| Project/Area Number |
11671065
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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 |
Kidney internal medicine
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| Research Institution | University of Occupational and Environmental Health |
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Principal Investigator |
OSAJIMA Akihiko UOEH, School of Medicine, Assistant professor, 医学部, 講師 (50248564)
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| Co-Investigator(Kenkyū-buntansha) |
OKAZAKI Masahiro UOEH, School of Medicine, Assistant professor, 医学部, 講師 (40233316)
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| Project Period (FY) |
1999 – 2000
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| Keywords | mesangial cells / glomerular hypertension / pressure / MCP-1 / adrenomedullin / MAP kinase / cAMP / transfection |
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| Research Abstract |
<Background> In glomerular hypertension, glomerular mesangial cells (MC) are subjected to high pressure. We previously reported that pressure by itself induced MC proliferation through activation of PKC and tyrosine kinases (Am. J.Physiol. 277 : F105, 1999). Furthermore, we have shown that adrenomedullin (AM) inhibited pressure-induced MC proliferation through activation of PKA (Nephron 83 : 352, 1999). In 5/6 nephrectomized rat, monocyte chemoattractant protein (MCP)-1 is expressed in glomeruli, suggesting the possible role of MCP-1 in the pathogenesis of glomerular sclerosis. In the present study, we examined the effects of pressure on MCP-1 expression in MC and the signal transduction patyways that lead to MCP-1 expression. In addition, we examined whether AM affects the pressure-induced MCP-1 expression in MC.
<Methods> Pressure was applied to MC by instilling compressed helium gas into sealed plates. MCP-1 mRNA and its protein levels were detected by RT-PCR or Western blotting, res
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pectively. MAP kinase activity was measured with the catalytic activity of p42/p44 MAP kinase and anti-phospho p42/p44 MAP kinase antibody. A transient transfection assay that specifically modulates MAP kinase kinase (MEK) activity was carried out.
<Results> 1. MC subjected to external pressure expressed MCP-1 mRNA rapidly and transiently with the peak level noted at 10 min and 80 mmHg pressure. MCP-1 protein levels in cell lysates and culture medium also significantly increased after pressure loading. Pressure rapidly increased the phosphorylation level and activity of p42/p44 MAP kinase. Treatment of MC with MEK inhibitor, PD98059, suppressed levels of both pressure-induced MAP kinase activities and MCP-1 mRNA expression. The constitutively activated type of MEK1 induced MCP-1 expression even in non-pressurized MC.
2. AM clearly inhibited pressure-induced both MCP-1 expression and its protein in a concentration-dependent manner. Forskolin and dibutyryl cAMP mimicked the inhibitory effect of AM.The PKA inhibitor H-89 significantly attenuated the effect of AM.AM inhibited pressure-induced MAP kinase activities.
<Conclusin> Our results suggest that glomerular hypertension might be involved in the progression of MCP-1 in MC.AM may play a protective role against MCP-1 expression in MC in glomerular hypertension. Less
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