title: A novel pathway from phosphorylation of tyrosine residues 239/240 of Shc, contributing to suppress apoptosis by IL-3.
abstract: Interleukin 3 (IL-3) not only induces DNA synthesis of haematopoietic cells but also maintains their viability by suppressing apoptosis. IL-3 stimulates tyrosine phosphorylation of the Shc adaptor protein and thereby formation of a complex of Shc with Grb2 at phosphorylated tyrosine (Y) residue 317-Shc. This pathway is implicated in Ras/mitogen-activated protein kinase (MAPK) activation towards c-fos gene expression. We examined the possible involvement of Shc in the antiapoptotic activity of IL-3. Conditional overexpression of the Shc SH2 domain, a dominant-negative mutant of Shc, was found to induce apoptosis of IL-3-dependent Ba/F3 cells along with a reduction of c-myc gene expression. Apoptosis was rescued by the exogenously introduced c-myc gene. Since we identify novel tyrosine phosphorylation sites of Shc: Y239 and Y240, their role on cell survival was tested by mutational analysis. Ba/F3 cells expressing mutant Shc Y317F, which is unable to stimulate efficiently the Ras pathway, still showed resistance to apoptosis. However, cells expressing Shc Y239/240F, which is able to stimulate the Ras pathway, were sensitive to apoptosis. In these cells, induction of the c-myc gene was reduced. These findings suggest that a new signalling pathway for cell survival is generated from Y239/240 of Shc to the nuclei involving c-myc gene expression.
authors.affiliation: Department of Genetics, Institute of Medical Science, University of Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Gotoh
authors.forename: A
authors.initials: A
authors.lastname: Tojo
authors.forename: M
authors.initials: M
authors.lastname: Shibuya
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000235:genetics; D016259:Genes, myc / Q000235:genetics; D007377:Interleukin-3 / Q000494:pharmacology*; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D014162:Transfection / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism*; D018909:src Homology Domains / Q000235:genetics*
chemical_list: D007377:Interleukin-3; D010748:Phosphopeptides; D014443:Tyrosine