The DDX5 protein is involved in proliferation and differentiation of human cultured cells

Abstract

Abstract—The expression of the DDX5 protein (RNA helicase p68) in cells correlates with processes of proliferation and differentiation. However, involvement of the protein in these processes has not been proven yet. In this paper, we have studied the effect of DDX5 protein inactivation (with small interfering RNAs) on the proliferation of Jurkat cell line and DDX5 expression dynamics during differentiation of U-937 cells induced by phorbol 12-myristate 13-acetate (PMA). Flow cytometry showed that the content of DDX5 in Jurkat cells in G0 and G1 phases was lower than compared with the G2/M phases. After induction of U-937 cell differentiation, an expression peak was observed during the first 2–3 h, followed by further reduction of the DDX5 concentration (4 h). The number of macrophage surface markers CR3 on the cell membrane increased only 24 h after PMA-induced cell differentiation. Hence, our data suggest that (1) the DDX5 protein is essential for cell proliferation and (2) the DDX5 protein concentration in U-937 cells increases during the first hours after stimulation with PMA followed by its decrease (after 4 ho) long before the macrophage marker appears on the cell surface.