Erythroid cell differentiation is characterized by nuclear matrix localization and phosphorylation of protein kinases C (PKC) α, δ, and ξ

Protein kinases C (PKC) xi expression and phosphoryation at nuclear level during dimethyl sulfoxide (DMSO)-induced differentiation in Friend erythroleukemia cells have been previously reported, suggesting a possible role of this PKC isoform in the DMSO-related signaling. In order to shed more light on this tantalizing topic, we investigated PKC intracellular and sub-cellular localization and activity during DMSO-induced erythroid differentiation. Results indicated that at least PKC a, C, and 8 are strongly and temporally involved in the DMSO-induced differentiation signals since their expression and phosphorylation, though at different extents were observed during treatments. Intriguingly, while PKC a and associate to the nuclear matrix during the differentiation event; PKC 8 appears to be residentially associated to the nuclear matrix. Furthermore an evident downregulation of the beta-globin gene transcription (differentiation hallmark) was detected upon a progressive inhibition of these PKC isoforms by means of specific inhibitors, indicating, therefore, that PKC a,, and 8 phosphorylation play a crucial role in the control of erythroid differentiation.