ACTIVATORS OF PROTEIN-KINASE-C STIMULATE ASSOCIATION OF SHC AND THE PEST TYROSINE PHOSPHATASE

Using the yeast two-hybrid system, complementary DNA clones were isola ted from a HeLa cell library encoding proteins that interacted with p5 2(shc). One of these clones encoded the non-catalytic, COOH-terminal h alf of the cytosolic protein tyrosine phosphatase PTP-PEST. Expression of truncated forms of p52(shc) in the two hybrid system revealed that the amino terminal half of p52(shc) was sufficient for interaction wi th PTP-PEST. The p52 and p66 forms of Shc, but not the p46 form, bound to a glutathione S-transferase fusion protein containing the region o f PTP-PEST isolated from the two-hybrid screen. Similarly, when HeLa c ell lysates were immunoprecipitated with PTP-PEST antiserum, p52(shc) and p66(shc) proteins, but not p46(shc), co-precipitated. Shc-PTP-PEST complex formation was stimulated 6-8 fold by the protein kinase C act ivator phorbol 12-myristate 13-acetate, while epidermal growth factor and serum had no effect. Phorbol 12-myristate 13-acetate also stimulat ed phosphorylation of p52(shc) and p66(shc). The muscarinic agonist ca rbachol (also an activator of protein kinase C) stimulated complex for mation 3-5-fold in SH-SY5Y neuroblastoma cells. These results suggest a role for PTP-PEST in G protein receptor signaling and in cross-talk between G protein receptor and tyrosine kinase receptor pathways.