Membrane localization of v-ErbB is required but not sufficient for ligand-independent transformation

• Published in: Experimental cell research Vol. 296; no. 2; pp. 285 - 293
• Main Authors: Danielsen, Andrew J, Christensen, Trace A, Lovejoy, Courtney A, Adelsman, Margaret A, Connolly, Denise C, Maihle, Nita J
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10-06-2004
• Subjects: AEV; Animals; Animals, Newborn; Cell Line; Cell Membrane - metabolism; Cell Transformation, Neoplastic; Chick Embryo; Chickens; EGF/ErbB receptors; Fibroblasts; Ligands; Mutagenesis, Site-Directed; Mutation; Neoplasms - etiology; Nuclear localization; Oncogene Proteins v-erbB - administration & dosage; Oncogene Proteins v-erbB - metabolism; Oncogene Proteins v-erbB - physiology; Protein Transport; Transformation, Genetic; Transmembrane domain; v-ErbB; AEV; v-ErbB; Nuclear localization; CEF; Transmembrane domain; EGF/ErbB receptors; EGFR
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2004.01.023

The v-ErbB retroviral oncogene is a transduced, mutated copy of the avian EGF receptor gene, and its expression is sufficient to induce tumor formation in vivo. The structural alterations that release the oncogenic potential of the v-ErbB oncogene are similar to EGFR gene mutations described in human tumors. Thus, the study of v-ErbB tumor biology offers a useful model through which we can gain insight into the mechanism of EGFR-induced malignancies. Despite years of study, however, questions remain regarding the domains of v-ErbB required for oncogenicity. We sought to clarify the role of the transmembrane domain of v-ErbB during transformation using S3-v-ErbB, an acutely transforming retroviral oncogene isolated from avian sarcomas. Infection of primary fibroblasts with a retroviral vector containing S3-v-ErbB results in the formation of a transformation-associated phosphoprotein signaling complex, soft agar colony formation, and the rapid induction of highly vascularized sarcomas in vivo. To address contribution of the transmembrane domain of S3-v-ErbB during these processes, we constructed a mutant version of this oncogene with a precise deletion in this domain. Specifically, the S3-v-ErbB-TM
− mutant was created through an in-frame deletion of the entire transmembrane domain. Primary fibroblasts expressing this S3-v-ErbB-TM
− mutant fail to form a characteristic transformation-associated phosphoprotein complex and do not grow in an anchorage-independent manner. In addition, day-old chicks injected with a helper-independent retrovirus expressing the S3-v-ErbB-TM
− mutant exhibit only limited tumor formation in vivo. These results demonstrate that the transmembrane domain and, consequently membrane localization, are essential for S3-v-ErbB-mediated transformation.