title: Activation of a CPP32-like protease during L1210 cell apoptosis induced by thiol deprivation.
abstract: Reduced thiols (e.g., cysteine) are important in the maintenance of lymphocyte cell viability and growth. L1210 monocytic leukaemia cells were known to have a limited ability to uptake cystine, and they require cysteine for cell growth. L1210 cells underwent apoptosis when cultured without thiol-bearing and dithiol-cleaving compounds, adding thiols suppressed the apoptosis and promoted cell growth. A specific inhibitor of interleukin-1 beta-converting enzyme (ICE)-like and CPP32-like proteases could suppress L1210 cell apoptosis induced by thiol deprivation. The cell lysates of apoptotic L1210 cells exhibited protease activity that could cleave DEVD-AMC, but not YVAD-AMC, and so CPP32-like proteases, but not ICE-like proteases, were activated and participated in apoptosis. The addition of thiols could suppress CPP32-like protease activation. Although the cell death-suppressor bcl-2-family proteins (bcl-2 and bcl-XL) were recently found to suppress the activation of CPP32-like proteases, the expression levels of death-suppressor bcl-2-family proteins did not change when thiols were added. These results suggest that reduced thiols maintain L1210 cell survival by inhibiting the activation of CPP32-like proteases without changing the anti-apoptotic bcl-2-family protein expression.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: N
authors.initials: N
authors.lastname: Fujita
authors.forename: T
authors.initials: T
authors.lastname: Tsuruo