The long journey of actin and actin-associated proteins from genes to polysomes.

During gene expression, multiple regulatory steps make sure that alterations of chromatin structure are synchronized with RNA synthesis, co-transcriptional assembly of ribonucleoprotein complexes, transport to the cytoplasm and localized translation. These events are controlled by large multiprotein complexes commonly referred to as molecular machines, which are specialized and at the same time display a highly dynamic protein composition. The crosstalk between these molecular machines is essential for efficient RNA biogenesis. Actin has been recently proposed to be an important factor throughout the entire RNA biogenesis pathway as a component of chromatin remodeling complexes, associated with all eukaryotic RNA polymerases as well as precursor and mature ribonucleoprotein complexes. The aim of this review is to present evidence on the involvement of actin and actin-associated proteins in RNA biogenesis and propose integrative models supporting the view that actin facilitates coordination of the different steps in gene expression.