Mechanism of carcinogenesis by the mutations of c-kit gene

c-kit基因突变致癌机制

• 批准号: 09670225
• 负责人: TSUJIMURA Tohru
• 金额: $ 2.3万
• 依托单位: Hyogo College of Medicine
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09670225/
• 关键词: c-kit receptor tyrosine kinase; mutation; carcinogenesis; stem cell factor; c-kit レセプターチロシンキナーゼ; 突然変異; c-kitレセプター チロシンキナーゼ

The c-kit receptor tyrosine kinase (KIT) is constitutively activated by naturally occurring mutations in either the juxtamembrane domain or the kinase domain. Although the juxtamembrane domain mutations led to ligand-independent KIT dimerization, the kinase domain mutations (Asp^<814>* Val or Tyr) did not. In an effort to determine if the kinase domain mutant could transfer oncogenic signaling without receptor dimerization, we have constructed the truncated types of c-kit^<wild> and c-kit^<Tyr814>cDNAs (c-kit^<Del-wild> and c-kit^<Del-Try814> cDNAs, respectively), in which ligand-binding and ligand induced dimerization domains were deleted. When c-kit^<Del-wild> and c-kit^<Del-Tyr814> genes were introduced into a murine interleukin (IL)-3-dependent cell line Ba/F3, KIT^<Del-Tyr814> was constitutively phosphorylated on tyrosine and activated., whereas KIT^<Del-wild> was not. In addition, Ba/F3 cells expressing KJT^<Del-Tyr814> (Ba/F3^<Del-Tyr814>) grew in suspension culture wihout the a … More ddition of exogenous growth factor, whereas Ba/F3 cells expressing KIT^<Del-wild> (Ba/F3^<Del-wild>) required IL-3 for growth. To test the possibility that KfIT^<Tyr814> may yield homodimeric and heterodimeric association of KIT not in the extracellular region, 293T cells were transfected with the combinations of various c-kit genes, and then the association of KIT was examined. KIT^<Tyr814> was found to be co-immunoprecipitated with KiT by an ACK2 monoclonal antibody directed against the extracellular domain of KIT.Moreover, KIT was constitutively associated with a chimericFMS/KIT^<Tyr814> receptor containing the ligand-binding and receptor dimerization domain of c-fms receptor (FMS) fused to the transmembrane and cytoplasmic domain of KIT^<Tyr814>, but not with a chimeric EMS/KIT^<wild> receptor even after stimulation with FMS-ligand. These results suggest that constitutively activating mutation of c-kit at the Asp^<814> codon may cause a conformation change that leads to receptor self-association not in the extracellular domain, and that the receptor self-association of the Asp^<814> mutant may be important for activation of downstream effectors that are required for factor-independent growth and tumorigenicity. Less

c-kit受体酪氨酸激酶（KIT）是由质膜结构域或激酶结构域中天然存在的突变组成型激活的。尽管质膜结构域突变导致配体非依赖性KIT二聚化，但激酶结构域突变（Asp^<814>* 瓦尔或Tyr）不会。为了确定激酶结构域突变体是否可以在没有受体二聚化的情况下传递致癌信号，我们构建了截短型c-kit^<wild>和c-kit^<Tyr814>cDNA（分别为c-kit^<Del-wild>和c-kit^<Del-Try814>cDNA），其中缺失了配体结合和配体诱导的二聚化结构域。当c-kit^<Del-wild>和c-kit^<Del-Tyr814>基因被引入鼠白细胞介素（IL）-3依赖性细胞系Ba/F3时，KIT^<Del-Tyr814>在酪氨酸上组成性磷酸化并被激活。而KIT^<Del-wild>不是。此外，表达KJT^<Del-Tyr814>（Ba/F3^<Del-Tyr814>）的Ba/F3细胞在无细胞因子的悬浮培养中生长， ...更多信息 而表达KIT^<Del-wild>（Ba/F3^<Del-wild>）的Ba/F3细胞需要IL-3才能生长。为了测试KfIT α<Tyr814>可以产生不在胞外区中的KIT的同源二聚体和异源二聚体缔合的可能性，用各种c-kit基因的组合转染293 T细胞，然后检查KIT的缔合。此外<Tyr814>，KIT与嵌合FMS/KIT^受体组成性结合，所述嵌合FMS/KIT^<Tyr814>受体含有c-fms受体（FMS）的配体结合和受体二聚化结构域，所述FMS结合和受体二聚化结构域融合到KIT^的跨膜和胞质结构域<Tyr814>，但<wild>即使在用FMS-配体刺激后也不与嵌合EMS/KIT^受体结合。这些结果表明，c-kit在Asp^密码子的组成型激活突变<814>可能导致构象变化，导致受体自缔合不在胞外结构域中，并且Asp^突变体的受体自缔合<814>对于激活因子非依赖性生长和致瘤性所需的下游效应物可能是重要的。少

项目成果

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