Inhibition of Transcription Induces Phosphorylation of YB-1 at Ser102 and Its Accumulation in the Nucleus

Abstract : The Y‐box binding protein 1 (YB‐1) is an RNA/DNA‐binding protein regulating gene expression in the cytoplasm and the nucleus. Although mostly cytoplasmic, YB‐1 accumulates in the nucleus under stress conditions. Its nuclear localization is associated with aggressiveness and multidrug resistance of cancer cells, which makes the understanding of the regulatory mechanisms of YB‐1 subcellular distribution essential. Here, we report that inhibition of RNA polymerase II (RNAPII) activity results in the nuclear accumulation of YB‐1 accompanied by its phosphorylation at Ser102. The inhibition of kinase activity reduces YB‐1 phosphorylation and its accumulation in the nucleus. The presence of RNA in the nucleus is shown to be required for the nuclear retention of YB‐1. Thus, the subcellular localization of YB‐1 depends on its post‐translational modifications (PTMs) and intracellular RNA distribution.