| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
This study was undertaken to examine the role of MAP kinases and AP-1 in glomerular injury using the gene transfer technique. (1) We examined the possible significance of MAP kinases and AP-1 in the molecular mechanism of growth of cultured mesangial cells. PDGF-BB stimulation significantly activated ERK, JNK and AP-1, followed by the significant increase in DNA synthesis and cell number. Dominant negative mutants of ERK, JNK or c-Jun significantly suppressed the growth of mesangila cells induced by PDGF-BB.These results show that ERK, JNK and AP-1 are involved in mesangial cell growth. (2) Overexpression of TGF-b1 in glomerular cells is shown to be responsible for the development of glomerulosclerosis. We examined the molecular mechanism of TGF-b1 overexpression, by transfecting the promoter gene of TGF-b1 into mesangial cells. PDGF-BB stimulation significantly increased the promoter activity of TGF-b1 in glomerular cells, and this increase was significantly suppressed by dominant negative mutants of ERK or c-Jun. Thus, ERK and AP-1 seem to participate in overexpression of TGF-b1 in glomerular cells. (3) We examined the role of MAP kinases and AP-1 in rat glomerulonephritis induced by anti-thy1 antibody injection. Glomerular ERK, JNK and AP-1 were rapidly and significantly activated in acute glomerulonephritis. Gene transfer of dominant negative mutants of ERK, JNK or c-Jun within the kidney via the renal artery failed to inhibit the increase in glomerular TGF-b1 or extracellular matrix or glomerular cell growth seen in glomerulonephritis. The failure of gene transfer of dominant negative mutants to prevent the development of glomerulonephritis possibly was due to the insufficient suppression of MAP kinase or AP-1 activation by the gene transfer technique. However, our in vitro study using gene transfer technique supports that MAP kinae and AP-1 are involved in the pathophysiology of glomerulosclerosis.
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