Functional p85 gene is required for normal murine fetal erythropoiesis

In vitro studies suggest that activation of class IA phosphatidylinositol 3 (PI-3) kinase is necessary for normal erythroid cell development. However, when class IA PI-3 kinase–deficient mice were generated by a targeted deletion of the p85 regulatory subunit, fetal erythropoiesis was reportedly unaffected. Given the discrepancies between these studies, we performed a more detailed in vivo analysis of class IA PI-3 kinase–deficient embryos. Day-14.5 p85 / embryos are pale with a marked reduction of mature erythrocytes in their peripheral blood. Further, the absolute number and frequency of both early (erythroid burst-forming unit [BFU-E]) and late erythroid progenitors (erythroid colony-forming unit [CFU-E]) are reduced in p85 / fetal livers compared with wild-type controls, which is associated with reduced proliferation. Taken together, these data establish an important role for p85 and class IA PI-3 kinase in regulating the development of both early and late erythroid progenitors in fetal liver. (Blood. 2003;102:142-145)