METALLOPROTEINASE GENERATION BY HUMAN GLOMERULAR EPITHELIAL-CELLS

In the present study cultured human glomerular epithelial cells (HGEC) were used to examine the potential role for these cells in the turnover of the glomerular basement membrane (GBM) through the secretion of matrix metalloproteinases. The cells were shown by substrate gel electrophoresis to secrete gelatinase activity of molecular weights 72 kDa and 92 kDa. The gelatinolytic activity was inhibited by EDTA (10 mM), and by both TIMP-I and TIMP-II, but was hot inhibited by PMSF (2.5 mM), indicating that th enzymes belonged tb the metalloproteinase family. The identity of the enzymes was confirmed by the use of specific antisera to gelatinase A and gelatinase B. In addition, reverse transcription polymerase chain reaction (RT PCR) amplification of HGEC mRNA using specific primers to the two enzymes yielded single bands of amplified DNA and served to verify the identity of the enzymes: In supplementary experiments using both specific antiserum and PCR primers it was shown that HGEC express message and secrete bath the specific metalloprotein ase inhibitors TIMP-I and TIMP-II. These results indicate that the synthesis and secretion of degradative enzymes and their controlling inhibitors by HGEC have the potential to be involved in the turnover of the extracellular matrix.