|Budget Amount *help
¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
Transforming growth factor (TGF)-beta is an important modulator in the initiation and progression of several types of glomerulonephritis. However, signal transduction mechanism of TGF-beta is not fully understood. To elucidate whether effect of TGF-beta is mediated GTP-binding protein (G-protein), we used G-protein recognizing peptides in cultured rat mesangial cells stimulated by TGF-beta. TGF-beta stimulated the accumulations of extracellular matrix such as fibronectin (FN) and collagen (COL) type IV in a dose-dependent manner. Goalpha recognizing peptide inhibited the accumulations of FN and COL type IV, but G-protein recognizing peptides against Gi, Gq and Gs did not. It was however difficult to make sure whether G-protein recognizing peptides pass through cell membrane. We then used Galphas chimeras consisting of the Galphas residues 1-389, which lacks the original five residues of Gas at the C-terminus of each known Galpha. Transient transfection of cDNA consisting of Galphas wild type, Galphas/alphai, Galphas/alphao, Galphas/alphaz and Galphas/alphaq was performed by the lipofectin method in cultured rat mesangial cells. Cells were then stimulated by 100 pM TGF-b and FN accumulation in the supernatant using ELISA.Galphas/alphao inhibited FN and COL type IV accumulations, but Galphas wild type, Galphas/alphai, Galphas/alphaz and Galphas/alphaq did not. These results suggest that signal transduction of TGF-beta in the regulation of extracellular matrix is mediated through Go.