Figure 4.

The pleotropic actions of FGF23 in anemia. As a direct consequence, FGF23 reduces the secretion of EPO from the kidney, thereby decreasing the differentiation of erythroid progenitors, such as pro-erythroblasts, to mature erythrocytes. In addition, FGF23 directly reduces the fraction of erythrocytes in the G2/M phase of their cell cycle and enhances erythrocyte apoptosis. As an indirect consequence, FGF23 enhances the inflammatory milieu, which in turn, promotes hepcidin excess and leads to the restriction of iron for erythropoiesis. EPO, erythropoietin; EPOR, erythropoietin receptor.