Roles of mitogen-activated protein kinase and phosphoinositide 3'-kinase in ErbB2/ErbB3 coreceptor-mediated heregulin signaling

Exp Cell Res. 2003 Apr 1;284(2):291-302. doi: 10.1016/s0014-4827(02)00040-x.


ErbB2/HER2 and ErbB3/HER3, two members of the ErbB/HER family, together constitute a heregulin coreceptor complex that elicits a potent mitogenic and transforming signal. Among known intracellular effectors of the ErbB2/ErbB3 heregulin coreceptor are mitogen-activated protein kinase (MAPK) and phosphoinositide (PI) 3-kinase. Activation of the distinct MAPK and PI 3-kinase signaling pathways by the ErbB2/ErbB3 coreceptor in response to heregulin and their relative contributions to the mitogenic and transformation potentials of the activated coreceptor were investigated here. To this end, cDNAs encoding the wild-type ErbB3 protein (ErbB3-WT) and ErbB3 proteins with amino acid substitutions in either the Shc-binding site (ErbB3-Y1325F), the six putative PI 3-kinase-binding sites (ErbB3-6F), or both (ErbB3-7F) were generated and expressed in NIH-3T3 cells to form functional ErbB2/ErbB3 heregulin coreceptors. While the coreceptor incorporating ErbB3-WT activated both the MAPK and the PI 3-kinase signaling pathways, those incorporating ErbB3-Y1325F or ErbB3-6F activated either PI 3-kinase or MAPK, respectively. The ErbB2/ErbB3-7F coreceptor activated neither. Elimination of either signaling pathway lowered basal and eliminated heregulin-dependent expression of cyclin D1, which was in each case accompanied by an attenuated mitogenic response. Selective elimination of the PI 3-kinase pathway severely impaired the ability of heregulin to transform cells expressing the coreceptor, whereas attenuation of the MAPK pathway had a lesser effect. Thus, while both pathways contributed in a roughly additive manner to the mitogenic response elicited by the activated ErbB2/ErbB3 coreceptor, the PI 3-kinase pathway predominated in the induction of cellular transformation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Animals
  • Cell Transformation, Neoplastic / genetics
  • Cyclin D1 / metabolism
  • Eukaryotic Cells / enzymology*
  • MAP Kinase Signaling System / genetics*
  • Mice
  • Mitosis / genetics
  • Mutation / genetics
  • Neuregulin-1 / genetics
  • Neuregulin-1 / metabolism*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Receptor, ErbB-2 / genetics
  • Receptor, ErbB-2 / metabolism*
  • Receptor, ErbB-3 / genetics
  • Receptor, ErbB-3 / metabolism*
  • Signal Transduction / genetics*


  • Neuregulin-1
  • Cyclin D1
  • Phosphatidylinositol 3-Kinases
  • Receptor, ErbB-2
  • Receptor, ErbB-3