RHOB regulates megakaryocytic and erythroid differentiation by altering the cell cycle and cytoskeleton

RHOB, a member of the RHO GTPase family, is a target of miR-1915-3p. miR-1915-3p was proven to promote the differentiation of megakaryocytes while inhibiting that of the erythroid lineage. Although RHOB has been shown to be involved in proplatelet production in mice, its role in early haematopoiesis, especially megakaryocytic and erythroid differentiation in humans, has not yet been elucidated. In this study, we demonstrated the function of RHOB by knocking down the gene in progenitor cells and inducing these cells to differentiate into erythroid or megakaryocytic cells. The silencing of RHOB significantly decreased the proportion of erythroid cells and inhibited the expression of related genes during erythroid differentiation while increasing the proportion of megakaryocytic and polyploid cells and promoting the expression of megakaryocytic lineage-specific genes in megakaryocyte-induced cells. RNA sequencing indicated that RHOB is involved in differentiation by regulating the cell cycle and cytoskeleton. Accordingly, we found that RHOB could differentially affect the expression of cyclin-dependent kinases and cyclins to alter the proportions of G₀/G₁-or S-phase cells and affect the expression or aggregation of beta-actin (ACTB) during erythroid or megakaryocytic differentiation. Directly overexpressing RHOA/RHOC in RHOB-downregulated cells showed that the effect of RHOB could be moderately compensated for by its homologs RHOA or RHOC. Taken together, these findings show that RHOB plays an important role in megakaryocytic and erythroid differentiation via the cell cycle and cytoskeleton regulation.