HER4 receptor activation and phosphorylation of Shc proteins by recombinant heregulin-Fc fusion proteins.
Heregulins (HRGs) are mosaic glycoproteins that bind to and induce the tyrosine phosphorylation of the HER4/p180erbB4 receptor. This work was aimed at studying the biological effects induced by recombinant epidermal growth factor (EGF)-like domains of HRGs as well as identifying intracellular molecules involved in HER4 signaling. To this end, we cloned the EGF-like domains of HRG-alpha, -beta 2, and -beta 3 into a eukaryotic expression vector in frame with sequences encoding a thrombin cleavage site followed by the Fc portion of a human IgG1. These chimeric genes directed the expression of recombinant fusion proteins, rHRGs-T-Fc, which specifically stimulated the phosphorylation of HER4/p180erbB4. We also show that rHRG-alpha-T-Fc bound to human breast cancer cells that express HER4 receptors and induced the expression of intercellular adhesion molecule-1. After thrombin protease cleavage of rHRGs-T-Fc, their EGF-like domains were purified and shown to stimulate protein phosphorylation in HER4-expressing cells. Moreover, the rHRG-beta 2 EGF-like domain markedly induced the phosphorylation of Shc proteins on tyrosine, suggesting a role for these adaptor molecules in HRG-mediated signaling.
Culouscou
J M
JM
Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121, USA.
Carlton
G W
GW
Aruffo
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001943:Breast Neoplasms; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000235:genetics; D066246:ErbB Receptors / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D008969:Molecular Sequence Data; D020880:Neuregulins; D010766:Phosphorylation; D011485:Protein Binding; D066247:Receptor, ErbB-4; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013917:Thrombin / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D006023:Glycoproteins; D007141:Immunoglobulin Fc Fragments; D020880:Neuregulins; D011993:Recombinant Fusion Proteins; D018799:Intercellular Adhesion Molecule-1; D014443:Tyrosine; D004815:Epidermal Growth Factor; C587689:ERBB4 protein, human; D066246:ErbB Receptors; D066247:Receptor, ErbB-4; D013917:Thrombin