Granulocyte macrophage‐colony stimulating factor stimulates both association and activation of phosphoinositide 3OH‐kinase and src‐related tyrosine kinase(s) in human myeloid derived cells.

Abstract

The signalling pathways used by the GM-CSF receptor are currently unknown. Here we show that in human myeloid derived cells GM-CSF can stimulate; (i) the accumulation of PtdIns(3,4,5)P 3 ; (ii) increases in p53/p56(lyn) and p62(c-yes) directed protein tyrosine kinase activities in anti-lyn and anti-c-yes antibody directed immunoprecipitates, respectively and; (iii) increases in phosphoinositide 3OH-kinase activity in antiphosphotyrosine, anti-p53/p56(lyn) and anti-p62(c-yes) antibody directed immunoprecipitates. These results suggest that GM-CSF can stimulate formation of protein tyrosine kinase co-ordinated signalling complexes, that contain p53/p56(lyn), p62(c-yes) and an activated PtdInsP 2 directed phosphoinositide 3OH-kinase, which can drive the accumulation of the putative second-messenger PtdIns(3,4,5)P 3 .