[The effect of intracellular protease inhibitors on DNA synthesis in fibroblasts from the NIH 3T3 mouse strain].
The enhancement of catabolic reactions of cell macromolecules, primarily proteins, raises the question about the role of active proteolysis and particular kinds of proteases in the process leading to cell proliferation retardation. The application of highly specific inhibitors of intracellular proteases helps to answer this question even in part. It has been shown that a short-term (2-6 h) treatment of resting cells of line NIH 3T3 with inhibitors of lysosomal cysteinous proteases--cystatine or leupeptin, as well as with inhibitors of non-lysosomal Ca(2+)-activated cystein proteases--L-cystamine and L-cystin--enhances the cell proliferative response on the serum and even stimulates tritiated thymidine incorporation in the cells cultured in the medium with a low (0.2%) serum content. Unlike, the treatment of resting cells with the lysosomotropic agent chloroquin, known to shut down all lysosomal hydrolases, reduces the cell proliferative response of the serum. In the experiments of fusing the resting and stimulated cells, it was found that the pretreatment of the former with inhibitors of lysosomal proteases enhanced the index of labeled nuclei in the latter, while observed in dikaryons, compared to the control, although failed to remove totally the effect of DNA synthesis inhibition in heterokaryons (Setkov et al., 1984; Setkov, Kazakov, 1989). A conclusion is made that the short-term metabolic shift in resting cells towards anabolism may result in that resting cells commit a cycle, and that an enhanced activity of cystein proteases is one of specific metabolic processes in resting cells leading to proliferation retardation.
Setkov
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D016475:3T3 Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002250:Carbon Radioisotopes; D002455:Cell Division / Q000187:drug effects; D002459:Cell Fusion / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects*; D051379:Mice; D011480:Protease Inhibitors / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors
D002250:Carbon Radioisotopes; D003470:Culture Media; D011480:Protease Inhibitors; D004247:DNA; D013936:Thymidine