Pike tyrosine phosphorylation regulates its apoptotic cleavage during programmed cell death

Growth factors provoke PIKE to enhance PI 3-kinase/Akt signaling cascade, and emerging evidence supports that PIKE robustly promotes cell survival. In the present study, we have discovered that PIKE is potently phosphorylated on tyrosine residues, leading to its resistance against the apoptotic cleavage by the cell-free apoptotsome. EGF triggers PIKE-A phosphorylation on both Y774 and Y682 residues. Diminishing tyrosine phosphorylation on PIKE-A by mutating either Y774 or 682 into F makes PIKE-A susceptible to apoptotic degradation. Moreover, growth factor pretreatment also attenuates the apoptotic cleavage of PIKE-A in human cancer cells. Thus, tyrosine phosphorylation may suppress proteolytic cleavage of PIKE-A and protect its anti-apoptotic activity, promoting cell survival. © 2006 Elsevier Ltd. All rights reserved.