Unpolymerized nuclear actin is involved in the activation of CSF-1 gene transcription.

Nuclear actin is a nuclear component in many kinds of eukaryotic cells but its function is still not clear. In this study, we overexpressed actin in nuclei and found that it promoted transcription of the CSF-1 gene, both exogenous and endogenous, approximately two-fold. Cytochalasin B did not affect this function of nuclear actin. Our results suggest that nuclear actin plays a role in regulating CSF-1 gene transcription, and this role does not depend on actin polymerization.