ACTIN CLEAVAGE BY CPP-32 APOPAIN DURING THE DEVELOPMENT OF APOPTOSIS/

Interleukin-1 beta-converting enzyme (ICE)/ced-3 family proteases play key roles in apoptosis, However, cellular substrates for ICE family p roteases involved in apoptosis are not well understood, We previously showed that actin is cleaved in vitro by an ICE family protease, disti nct from ICE itself, which is activated during VP-16-induced apoptosis , In this report, we demonstrate that the actin-cleaving ICE-family pr otease in the apoptotic cell extract is the activated CPP-32/apopain. CPP-32 effectively cleaves actin protein to 15 kDa and 31 kDa fragment s, Studies with an antibody raised against Gly-Gln-Val-Ile-Thr peptide , the N-terminal sequence of the cleaved 15 kDa actin fragment, showed that actin is also cleaved in vivo during the development of apoptosi s, Moreover, carbonyl-Glu-Val-Asp-CH2OC(O)-2,6,-dichlorobenzene (Z-EVD -CH2-DCB), a selective inhibitor of CPP-32(-like) protease, efficientl y inhibited the cleavage of actin and the apoptosis of VP-16-treated U 937 cells, Our present results indicate that actin is the substrate of CPP-32/apopain(-like) protease both in vitro and ill vivo and suggest the role of actin in the control of cell growth and apoptosis,