Cytochalasin D inhibits nuclear translocation of nonhistone proteins induced by lectin and other agents in lymphocytes.

Cytochalasin D (CD), known to interfere with microfilament activity, inhibits RNA and protein synthesis and the cellular uptake of [3H]actinomycin D in concanavalin A-stimulated lymphocytes. It also inhibits the nuclear translocation of nonhistone proteins (NHP) induced by the lectin. Since NHP mediate RNA and protein synthesis and [3H]actinomycin D binding, inhibited nuclear translocation of NHP can explain the inhibition of the former events. CD also inhibits nuclear translocation of NHP caused by NaF or chloroquine. The mechanism of how CD inhibits nuclear translocation of the NHP is obscure. Since NaF and chloroquine enter cells by diffusion, it would appear that CD acts on an intracellular target, rather than abrogating a cell surface-mediated signal generated by binding of the lectin to a cell surface receptor.