Mechanisms of apoptotic cell death caused by radiation-induced perturbation in checkpoint regulations.

为了阐明辐射诱导的有丝分裂检查点调控引起的染色体不稳定和凋亡的机制，我们分离了调节有丝分裂细胞分裂的丝氨酸/苏氨酸蛋白激酶，并分析了它们与凋亡细胞死亡相关的特性。近3年的研究成果总结如下：在有丝分裂期间，组蛋白H3 Ser-10位点的磷酸化是维持适当的染色体动力学所必需的。我们发现，在体外培养的哺乳动物细胞中，外源性过表达Aurora-B激酶AIM-1会导致有丝分裂时Ser-10磷酸化增加，并伴随有丝分裂时染色体滞后，并且AIM-1过表达的细胞在体内表现为染色体数目不稳定和肿瘤侵袭性增加。这些数据表明，AIM-1过表达导致的H3组蛋白磷酸化增加是染色体不稳定的主要诱发因素，因此可能在癌变中起作用。2 .更多。为了分析各种哺乳动物细胞在电离辐射照射下延迟凋亡的机制，我们研究了γ或紫外线辐射对细胞凋亡的诱导作用，并比较了线粒体信号通路的激活。结果表明，细胞凋亡的延迟或快速形式强烈依赖于辐射类型，可能是由于调节线粒体释放细胞色素c的细胞质因子的存在，该因子在细胞凋亡信号通路的上游起作用。由于极光激酶- a的过表达和野生型p53功能的丧失会导致类似的染色体不稳定，这在恶性转化过程中很常见，我们分析了极光激酶- a磷酸化与p53活性的关系。我们的数据表明，过表达Aurora-A导致p53降解增加，导致检查点反应通路下调，对凋亡细胞死亡产生耐受性。少

To elucidate the mechanisms of chromosome instability and apoptosis caused by radiation-induced perturbations in mitotic checkpoint regulations, we have isolated serin/threonine protein kinases that regulate mitotic cell division and analyzed their properties associated with apoptotic cell death. The results obtained for the past 3 years can be summarized as follows:1. Phosphorylation of histone H3 at Ser-10 is required for maintenance of proper chromosome dynamics during mitosis. We found that exogenous overexpression of Aurora-B kinase AIM-1 in cultured mammalian cells caused increased mitotic Ser-10 phosphorylation with concomitant of lagging chromosomes during mitosis, and that chromosome number instability and increased tumor invasiveness were noted AIM-1 overexpression cell in vivo. These data suggest that increased H3 histone phosphorylation as a result of AIM-1 overexpression is a major precipitating factor of chromosome instability and, thus may play a role in carcinogenesis.2 … More . To analyze the mechanism of delayed form of apoptosis that is a common feature of various mammalian cells when irradiated with ionizing radiation, we examined the induction of apoptosis by γ or UV radiation and compared the activation of mitochondrial signaling pathways. The results indicate that delayed or rapid form of apoptosis strongly depend on types of radiation and might be due to the existence of cytosolic factors regulating release of cytochrome c from mitochondria, which functions at the upstream of apoptosis signaling pathways.3. Since overexpression of Aurora kinase-A and loss of wild-type of p53 function induce similar chromosome instability, which commonly appears in the process of malignant transformation, we have analyzed the relationship between the phosphorylation of Aurora-A and p53 activity. Our data suggest that overexpression of Aurora-A lead to increased degradation of p53, causing downregulation of checkpoint-response pathways and tolerance to apoptotic cells death. Less