LPS-induced signals in activation of a caspase-3-like protease, a key enzyme regulating apoptotic cell damage into a macrophage-like cell line, J774.1, in the presence of cycloheximide

The earliest observed apoptotic change in a macrophage-like cell Line, J774 .1, treated with lipopolysaccharide (LPS) in the presence of cycloheximide (CHX) was a selective increase in caspase-3-like activity. The addition of polymyxin B, TPCK, herbimycin A, or genistein, all of which inhibited LPS-i nduced tumor necrosis factor alpha (TNF-alpha) production by macrophages, s uppressed the activation of the caspase-3-like protease in these macrophage s treated simultaneously with CHX, However, SB202190 and SB203580, inhibito rs of MAP kinase, and PD98059, an inhibitor of MAP-kinase kinase (MEK), sho wed no effect on the activation of the caspase-3-like protease or on the ce ll damage of the macrophages treated with LPS and CHX, whereas they inhibit ed LPS-induced TNF-alpha production. These results suggest that some of the early signals in LPS-treated macrophages are common to the subsequent path ways for TNF-a production and caspase-3-like protease activation, but the l ater signals, like MAP-kinase kinase or MAP-kinase, are not involved in the pathways for caspase-3-like protease activation.