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

Protein kinases C (PKC) ζ 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 α, ζ, and δ 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 α and ζ associate to the nuclear matrix during the differentiation event, PKC δ appears to be residentially associated to the nuclear matrix. Furthermore, an evident downregulation of the β‐globin gene transcription (differentiation hallmark) was detected upon a progressive inhibition of these PKC isoforms by means of specific inhibitors, indicating, therefore, that PKC α, ζ, and δ phosphorylation play a crucial role in the control of erythroid differentiation. © 2005 Wiley‐Liss, Inc.