Differential expression patterns of beta-actin mRNA in cells undergoing apoptosis.

Microfilaments play an important role in the formation of apoptotic bodies. This study examined expression patterns of beta-actin, a key component of microfilament, during apoptosis. The data suggest that continuous beta-actin expression is not required for formation of apoptotic bodies. beta-actin mRNA levels rapidly declined in HL-60 cells following induction of apoptosis by actinomycin D, but were transiently elevated by two other apoptosis-inducing agents, cycloheximide and ionophore A23187. Furthermore, changes in beta-actin mRNA levels were less marked in U937 cells in which apoptosis was also induced by actinomycin D, as well as in WISH cells which demonstrated no typical apoptotic characteristics following actinomycin D treatment.