CD44 clustering is involved in monocyte differentiation.

Differentiation of monocytes into macrophages is an important process under physiological and pathological conditions, but the underlying mechanism of monocyte differentiation is not completely clear. Some adhesion molecules have been reported to play an important role in cell differentiation. CD44 is an important adhesion molecule that mediates cell-cell and cell-matrix interaction, and participates in a wide variety of cellular functions. As CD44 has been reported to show different activated states between monocytes and macrophages, we propose that CD44 may be involved in monocyte differentiation. In this study, we explored the role of CD44 in monocyte differentiation and further studied the mechanisms that were involved in. THP-1 cells (human monocytic leukemia cell line) were induced with phorbol 12-myristate 13-acetate (PMA) to establish the model of monocyte differentiation in vitro. It was found that CD44 expression and binding capacity to hyaluronic acid were increased significantly, and the distribution of CD44 was converted into clusters during differentiation. The PMA-induced CD44 clustering and CD44 high expression were suppressed by blocking CD44, which resulted in the inhibition of CD14 expression. PMA-induced phosphorylation of ERK1/2 signal was also suppressed by blocking CD44. Our results suggested that CD44 was involved in monocyte differentiation. The mechanisms of monocyte differentiation following CD44 activation may include CD44 high expression and clustering which in turn lead to phosphorylation of ERK1/2.