GENE-TRANSFER OF METALLOPROTEINASE TRANSIN INDUCES ABERRANT BEHAVIOR OF CULTURED MESANGIAL CELLS

The aim of the present study is to clarify whether the cellular expres sion of a matrix-degrading metalloproteinase, transin, alters the beha vior of cultured mesangial cells (MCs). The cDNA encoding rat transin was introduced into rat MCs and transcribed under the control of a Rou s sarcoma virus promoter. The resulting transfectants were then invest igated for cell shape, migration, proliferation, and expression of gen es associated with matrix metabolism. Northern blot analysis routinely detected the transin transcript in two separate transfectants, MeTRN2 and MeTRN5. Transin expression was strong in MeTRN2, moderate in MeTR N5, but absent in mock transfectants. Immunoblot analysis revealed tha t these transin transfectants synthesized 59 and 62 kDa molecules, whi ch correspond to transin gene products. Casein digestion assay detecte d enhanced proteolytic activity in MeTRN2 and MeTRNS. Microscopically, the transfected cells were somewhat elongated with accentuated margin s compared with mock transfectants. [H-3]-thymidine uptake studies rev ealed accelerated growth of the transfectants on a plastic substratum as well as within gel matrix. The migration of the transfectants into gel matrix was also significantly enhanced compared with that of mock transfectants. No obvious alteration, however, was found in transcript s of procollagen alpha 1(IV), laminin B-2, or the metalloproteinase in hibitor TIMP. We hypothesize that the metalloproteinase transin has a potential for affecting the behavior of MCs and contributing to the pa thogenesis of glomerular injury.