Open AccessDistinct Tyrosine Autophosphorylation Sites Negatively and Positively Modulate Neu-Mediated Transformation
Author(s) -
David Dankort,
Zhixiang Wang,
Valerie Blackmore,
Michael F. Moran,
William J. Muller
Publication year - 1997
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.17.9.5410
Subject(s) - autophosphorylation , biology , tyrosine , receptor tyrosine kinase , tyrosine phosphorylation , phosphorylation , tyrosine kinase , microbiology and biotechnology , immunoreceptor tyrosine based activation motif , receptor protein tyrosine kinases , grb2 , erbb , signal transduction , sh2 domain , ror1 , biochemistry , platelet derived growth factor receptor , receptor , protein kinase a , growth factor
A number of cytoplasmic signaling molecules are thought to mediate mitogenic signaling from the activated Neu receptor tyrosine kinase through binding specific phosphotyrosine residues located within the intracellular portion of Neu/c-ErbB-2. An activated neu oncogene containing tyrosine-to-phenylalanine substitutions at each of the known autophosphorylation sites was generated and assessed for its specific transforming potential in Rat1 and NIH 3T3 fibroblasts. Mutation of these sites resulted in a dramatic impairment of the transforming potential of neu. To assess the role of these tyrosine phosphorylation sites in cellular transformation, the transforming potential of a series of mutants in which individual tyrosine residues were restored to this transformation-debilitated neu mutant was evaluated. Reversion of any one of four mutated sites to tyrosine residues restored wild-type transforming activity. While each of these transforming mutants displayed Ras-dependent signaling, the transforming activity of two of these mutants was correlated with their ability to bind either the GRB2 or SHC adapter molecules that couple receptor tyrosine kinases to the Ras signaling pathway. By contrast, restoration of a tyrosine residue located at position 1028 completely suppressed the basal transforming activity of this mutated neu molecule or other transforming neu molecules which possessed single tyrosine residues. These data argue that the transforming potential of activated neu is mediated both by positive and negative regulatory tyrosine phosphorylation sites.