MUTATIONAL AND FUNCTIONAL ANALYSIS OF THE P53 TUMOR SUPPRESSOR GENE

P53 肿瘤抑制基因的突变和功能分析

• 批准号: 6289169
• 负责人: CURTIS HARRIS
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 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/6289169
• 关键词: DNA binding protein; DNA damage; apoptosis; carcinogenesis; flow cytometry; frameshift mutation; gene deletion mutation; gene mutation; helicase; human genetic material tag; human tissue; microinjections; molecular oncology; neoplasm /cancer genetics; protein sequence; protein structure function; stainings; tumor suppressor genes

We are investigating the molecular mechanisms of p53-mediated apoptosis. Our previous studies have identified a novel pathway of apoptosis involving the functional and physical interaction of p53 with DNA helicases, XPB and XPD. We have extended these studies to other members of the RecQ helicase family, BLM and WRN, that are linked to cancer predisposition syndromes, Bloom and Werner, respectively. Germline mutations in WRN are found in patients with the premature aging and cancer susceptibility syndrome known as Werner syndrome (WS). p53 binds to the WRN protein in vivo and in vitro through its carboxyl terminus. WS fibroblasts have an attenuated p53-mediated apoptotic response, and this deficiency can be rescued by expression of wild-type WRN. These data support the hypothesis that p53 can induce apoptosis through the modulation of specific DExH-containing DNA helicases and may have implications for the cancer predisposition observed in WS patients.Bloom syndrome (BS) is an autosomal recessive genomic instability syndrome characterized by growth retardation, immune deficiency and cancer predisposition. Similar to cells from XPB, XPD or WS individuals who have an attenuated p53-dependent apoptotic pathway, p53-mediated apoptosis also is defective in BS fibroblasts. This apoptotic pathway can be functionally rescued by the expression of the wild-type (wt) BLM gene. Lymphoblastoid cell lines (LCLs) derived from BS donors are resistant to either gamma-radiation or adriamycin-induced cell killing, and also can be rescued by the wt BLM. In contrast, BS cells have a normal Fas-mediated apoptosis, and a normal DNA damage- induced p53 accumulation and G1-S and G2-M cell cycle checkpoints. BLM localizes in nuclear foci identified as PML nuclear bodies (NBs), a structure that also contains the promyelocytic leukemia protein (PML), Rb, SUMO-1 and others, and may be involved in apoptosis. Cells from Li- Fraumeni syndrome (LFS) patients carrying p53 germline mutations have a decreased number of BLM foci. The induction of p53 increased the number of BLM foci, but did not alter either BLM levels or the number of NBs. These results indicate a novel function of p53 and are consistent with the hypothesis that, nuclear trafficking of BLM to NBs mediated by p53, contributes to its apoptotic activity. - Apoptosis, DNA repair, p, , Tumor Suppressor, - Human Tissues, Fluids, Cells, etc.

我们正在研究p53介导的细胞凋亡的分子机制。我们之前的研究已经发现了一种新的凋亡途径，涉及p53与DNA解旋酶、XPB和XPD的功能和物理相互作用。我们已经将这些研究扩展到RecQ解旋酶家族的其他成员，BLM和WRN，它们分别与癌症易感性综合征有关，Bloom和Werner。WRN的种系突变见于被称为Werner综合征（WS）的早衰和癌症易感综合征患者。p53通过其羧基末端在体内和体外与WRN蛋白结合。WS成纤维细胞具有减弱的p53介导的凋亡反应，这种缺陷可以通过野生型WRN的表达来弥补。这些数据支持了p53可以通过调节特定的含dexh的DNA解旋酶诱导细胞凋亡的假设，并可能与WS患者观察到的癌症易感性有关。Bloom综合征（BS）是一种常染色体隐性基因组不稳定综合征，以生长迟缓、免疫缺陷和癌症易感性为特征。与来自XPB， XPD或WS个体的细胞具有减弱的p53依赖性凋亡途径类似，p53介导的凋亡在BS成纤维细胞中也存在缺陷。野生型（wt） BLM基因的表达可以在功能上挽救这一凋亡途径。来自BS供体的淋巴母细胞样细胞系（LCLs）对γ辐射或阿霉素诱导的细胞杀伤具有抗性，并且也可以被wt BLM拯救。相比之下，BS细胞有正常的fas介导的凋亡，正常的DNA损伤诱导的p53积累和G1-S和G2-M细胞周期检查点。BLM定位于被称为PML核体（NBs）的核灶，该结构还含有早幼粒细胞白血病蛋白（PML）、Rb、SUMO-1等，可能参与细胞凋亡。Li- Fraumeni综合征（LFS）患者携带p53种系突变的细胞BLM灶数量减少。p53的诱导增加了BLM灶的数量，但没有改变BLM水平或nb的数量。这些结果表明了p53的一种新功能，并与p53介导的BLM向NBs的核运输有助于其凋亡活性的假设相一致。-细胞凋亡，DNA修复，p，肿瘤抑制，-人体组织，液体，细胞等