LIGAND REQUIREMENTS OF ERBB-2 TO CAUSE CELL TRANSFORMATION

ERBB-2 引起细胞转化的配体要求

• 批准号: 3874778
• 负责人: P P DI FIORE
• 金额: --
• 依托单位: DIVISION OF CANCER EPIDEMIOLOGY AND GENETICS
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3874778
• 关键词: chimeric proteins; epidermal growth factor; genetic manipulation; growth factor receptors; mitogens; monoclonal antibody; oncogenes; protein engineering; protein tyrosine kinase; transfection

The gpl85 erbB-2 receptor-like molecule is tyrosine phosphorylated in vivo in hematopoietic, mammary epithelial and fibroblast cell lines. This phenomenon can be explained by three hypotheses: (1) a ligand is produced by all of these cell lines; (2) a ligand is present in the tissue culture medium: and (3) the gpl85 erbB-2 is constitutively active. These hypotheses were tested studying the phosphorylation status of erbB-2 in a chemically defined medium and the transforming and biochemical activities of a chimeric molecule bearing the extracellular domain of erbB-2 and the intracellular domain of the epidermal growth factor receptor (erbB-2 EC/EGFR IC). This chimeric molecule was engineered by taking advantage of unique restriction sites generated in erbB-2 and EGFR cDNAs at homologous positions. This molecule was shown to be indistinguishable from the parental erbB-2 as assessed by its ability to bind a panel of monoclonal antibodies raised against the protein in its native configuration. Furthermore, it could be biochemically and biologically stimulated in vivo by some of these monoclonal antibodies. increasing its phosphotyrosine content and delivering a mitogenic signal. Nevertheless, this molecule showed no transforming activity in a transfection assay and no tyrosine phosphorylation in vivo when expressed in NIH/3T3 cells at levels comparable to its parental molecules. The erbB-2 molecule, therefore, seems to be endowed with constitutive kinase and biological activities. The use of down-regulating agents in order to achieve reversion of the transformed phenotype seems a rational possibility on the basis of these data.

gpl85 erbB-2 受体样分子在体内被酪氨酸磷酸化 在造血细胞、乳腺上皮细胞和成纤维细胞系中。这 这种现象可以用三个假设来解释：（1）产生配体 由所有这些细胞系； (2) 组织培养物中存在配体 中等：(3) gpl85 erbB-2 具有组成型活性。这些假设 进行了化学测试，研究了 erbB-2 的磷酸化状态 确定的培养基以及a的转化和生化活性 带有 erbB-2 胞外结构域的嵌合分子 表皮生长因子受体 (erbB-2) 的细胞内结构域 EC/EGFR I​​C)。这种嵌合分子是通过利用 在 erbB-2 和 EGFR cDNA 中同源产生独特的限制性位点 职位。该分子被证明与 通过其结合一组单克隆抗体的能力来评估亲本 erbB-2 针对天然构型的蛋白质产生的抗体。 此外，它可以在体内受到生化和生物学刺激 通过其中一些单克隆抗体。增加其磷酸酪氨酸 内容并传递促有丝分裂信号。尽管如此，这个分子 在转染测定中没有表现出转化活性，并且不含酪氨酸 在 NIH/3T3 细胞中表达时的体内磷酸化水平 与其母体分子相当。因此，erbB-2 分子似乎 被赋予组成型激酶和生物活性。用途 下调剂以实现转化的逆转 根据这些数据，表型似乎是合理的可能性。