STRUCTURE AND FUNCTION OF CTCF--TRANSGENIC MICE STUDIES

描述：（改编自研究者摘要）CTCF是一种 进化保守的11锌指（ZF）转录因子，具有多个 DNA序列特异性。CTCF-靶位点存在于几种转录因子的启动子中。 基因包括c-myc、Polo样激酶和Pim-1癌基因。平时 负调节细胞增殖。CTCF基因定位于 人类染色体16q22.1基因座在一个区域内， 癌症相关缺失我们的CTCF突变分析揭示了几个 肿瘤特异性突变导致不同位置的氨基酸取代 对于ZF形成或DNA碱基识别至关重要的位置。每个 突变选择性地消除CTCF与一些但不是所有靶DNA的结合 位点，这表明突变CTCF蛋白的致癌潜力可能 CTCF调节的靶基因谱的改变。这些 研究结果为CTCF作为候选肿瘤的作用提供了第一个证据 抑制基因位于16 q22。 然而，最有说服力的实验方法来证明一个 CTCF介导的肿瘤表型会增强肿瘤的观察 CTCF缺陷小鼠的易感性。我们的初步结果 证明CTCF（+/-）敲除小鼠易发生肿瘤 与野生型同窝仔相比，因此，根据我们的 p53和p27（Kip 1）缺陷小鼠的经验，我们计划扩大 分析CTCF（+/-）小鼠以研究CTCF的详细作用 单倍型不足对自发性，辐射-，ENU-，DMBA-，和其他 致癌物诱发的肿瘤倾向。似乎没有组织或 对含CTCF的RNA信息呈阴性的细胞系。同源基因敲除 转基因小鼠中的CTCF导致早期胚胎致死。因此，我们认为， 在癌症中CTCF功能的完全丧失是不可能的，因为它可能 与细胞增殖不相容。这一假设将由以下人员进行检验： 分析剩余野生型CTCF等位基因的失活机制 （突变和/或改变的表达）在由不同的 在辐射或致癌物激发的CTCF（+/-）小鼠中的组织中。此外，本发明还提供了一种方法， 我们将测试CTCF无效突变是否会导致植入前死亡 如果TCF具有“细胞自主”的基本和普遍性， 功能我们还预期与其他易患肿瘤的小鼠进行遗传杂交， p53和p27缺陷小鼠揭示遗传途径， CTCF缺陷在正常发育和肿瘤发生中的作用

DESCRIPTION: (Adapted from the investigator's abstract) CTCF is an evolutionarily conserved 11 Zinc finger (ZF) transcription factor with multiple DNA sequence specificity. CTCF-target sites are found in promoters of several genes including c-myc, Polo-like kinase and Pim-1 oncogenes. Normally, it negatively regulates cell proliferation. The CTCF gene is localized at the human chromosome locus 16q22.1 within a region that displays frequent cancer-associated deletions. Our mutational analysis of CTCF revealed several tumor-specific mutations resulting in amino acid substitutions at different positions critical either for ZF formation or for DNA base recognition. Each mutation selectively eliminates CTCF binding to some but not to all target DNA sites, suggesting that the oncogenic potential of mutant CTCF proteins may result from shifting the spectrum of target genes regulated by CTCF. These findings provide the first evidence for role of CTCF as a candidate tumor suppressor gene at 16q22. However, the most convincing experimental approach to demonstrate a CTCF-mediated cancer phenotype would be an observation of enhanced tumor susceptibility in CTCF deficient mice. Our preliminary results conclusively demonstrate that CTCF (+/-) knockout mice are predisposed to tumor development in multiple tissues compared to wild type littermates. Therefore, based on our experience with the p53 and p27 (Kip1) deficient mice, we plan to expand analyses of CTCF(+/-) mice to study in detail effects of CTCF haplo-insufficiency on spontaneous, radiation-, ENU-, DMBA-, and other carcinogens- induced tumor predisposition. There appears to be no tissue or a cell line negative for CTCF-containing RNA message(s). Homologous knockout of CTCF in transgenic mice results in early embryonic lethality. Therefore, complete loss of CTCF function in cancer is unlikely because it may be incompatible with cell proliferation. This hypothesis will be tested by analyzing mechanisms of inactivation of the remaining wild type CTCF allele (mutations and/or altered expression) in tumors developing from different tissues in irradiated or carcinogen- challenged CTCF (+/-) mice. In addition, we will test whether CTCF null mutation results in preimplantation lethality that may be expected if TCF has "cell-autonomous" essential, and universal function. We also anticipate genetic crosses to other tumor-prone mice such as p53 and p27 deficient mice to reveal genetic pathways, which cooperate with CTCF deficiency in normal development and tumorigenesis.