Oncogenic Kit receptor signaling in vivo

描述(申请人提供)：这项建议的总体目标有两个，1)继续我们体内致癌Kit受体信号的研究，重点是造血作用；2)发展对伊马替尼耐药的GIST小鼠模型。小鼠W基因座编码的Kit受体在造血、配子发生、黑素合成和肠道运动中起作用。Kit受体介导的正常功能包括细胞增殖、细胞存活、细胞黏附、细胞迁移、分泌反应和分化。在人类肿瘤中，Kit的致癌激活在胃肠道间质瘤(GIST)、肥大细胞增多症/肥大细胞白血病、急性髓系白血病、黑色素瘤亚群和生殖细胞肿瘤亚群中发挥作用。KIT受体的功能是通过激酶激活、受体自身磷酸化以及与各种信号分子和信号级联反应来介导的。在胚胎发育和出生后的动物中，受体酪氨酸激酶是如何在不同的细胞类型中介导不同的细胞反应的？在不同类型的细胞中发生致癌转化产生癌症的要求是什么？我们已经培育出了含有Kit受体基因敲击点突变的小鼠，这些突变阻断了Kit介导的PI 3-K激活和信号转导或Src家族激酶、SFK、激活和信号转导。这些小鼠在配子发生和造血方面具有明显不同的表型。我们还研究了PI3-激酶和Src家族激酶信号在Kit介导的骨髓肥大细胞(BMMC)体外增殖、抑制细胞凋亡、细胞黏附、趋化和分泌反应中的作用。Kit介导的PI3K信号在细胞增殖、细胞存活、细胞黏附、趋化和分泌反应中起关键作用，而Kit介导的SFK信号大多具有负调控作用。此外，基因表达谱显示，阻断SFK信号会降低KitL诱导的BMMC中TH2-细胞因子基因的表达。为了研究致癌试剂盒激活试剂盒在肿瘤发生中的作用，我们制造了携带膜旁区域敲入试剂盒突变的小鼠，并复制了人类家族性GIST综合征(Sommer等人，2003年)。在我们提出的部分研究中，我们将试图探讨PI3-激酶、SFK和RAS信号在Kit介导的肿瘤发生中的作用。此外，我们还将培育并鉴定携带伊马替尼耐药Kit等位基因的小鼠。

DESCRIPTION (provided by applicant): The overall objective of this proposal is twofold, 1) to continue our investigations of oncogenic Kit receptor signaling in vivo with emphasis on hematopoiesis and 2) to develop mouse models for imatinib resistant GIST. The Kit receptor encoded at the murine W locus functions in hematopoiesis, gametogenesis, melanogenesis and gut motility. Normal Kit receptor mediated functions include cell proliferation, cell survival, cell adhesion, cell migration, secretory responses and differentiation. In human neoplasia oncogenic activation of Kit has roles in gastrointestinal stromal tumors (GIST), mastocytosis/mast cell leukemia, acute myelogenous leukemia, a subset of melanomas and a subset of germ cell tumors. Kit receptor functions are mediated by kinase activation, receptor autophosphorylation and association with various signaling molecules and signaling cascades. How do receptor tyrosine kinases such as Kit mediate distinct cellular responses in different cell types during embryonic development and in the postnatal animal? And what are the requirements for oncogenic transformation in different cell types to produce cancer. We have produced mice containing knock-in point mutations in the Kit receptor gene in mice which block Kit mediated PI 3-kinase activation and signaling or Src family kinase, SFK, activation and signaling. These mice have distinctly different phenotypes in gametogenesis and hematopoiesis. We have also investigated the role of PI 3-kinase and Src family kinase signaling in Kit mediated cell proliferation, suppression of apoptosis, cell adhesion, chemotaxis and secretory responses in vitro in bone marrow derived mast cells (BMMC). Whereas Kit mediated PI 3-kinase signaling is critical for cell proliferation, cell survival, cell adhesion, chemotaxis and secretory responses, Kit mediated SFK signaling has mostly a negative regulatory role. Furthermore, gene expression profiling indicates that blocking SFK signaling reduces KitL induced expression of TH2-cytokine genes in BMMC. To investigate the role of oncogenic Kit activation Kit in tumorigenesis we have produced mice carrying a juxtamembrane domain knock-in Kit mutation and reproduced human familial GIST syndrome (Sommer et al., 2003). In part our proposed studies will attempt to investigate the role of PI 3-kinase, SFK and Ras signaling in Kit-mediated tumorigenesis. Furthermore we will produce and characterize mice carrying oncogenic imatinib resistant Kit alleles.