Involvement of PI3K[gamma] in the regulation of erythroid differentiation of K562 cells
In the present study, the role of PI3K[gamma] in erythroid differentiation was investigated. PI3K[gamma] expression was found to be inversely correlated with the induced erythroid differentiation of human hematopoietic stem cells and that of K562 cells. Using both antisense and overexpression strategies, a negative role of PI3K[gamma] in the erythroid differentiation of K562 cells was established, and this function of PI3K[gamma] is presumably due to its protein kinase activity. Using immunoprecipitation and subsequent protein kinase assay, two proteins with molecular weight of approximately 70 kDa and 50 kDa were observed to be the in vitro targets for PI3K[gamma] protein kinase activity, and could be the possible candidates that mediate the inhibitory effect of PI3K[gamma] on erythroid differentiation in vitro. The identification of these proteins and the elucidation of their downstream signalling events linked to the erythroid-specific gene(s) expression are the aim of our future investigations.