Elucidation of the mechanisms by which regulate DNA damage checkpoints in mammals

阐明哺乳动物 DNA 损伤检查点的调节机制

• 批准号: 13470027
• 负责人: NAKANISHI Makoto
• 金额: $ 9.28万
• 依托单位: Nagoya City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13470027/
• 关键词: Cell cycle; checkpoints; Cdc25; Chk1; Chk2; Cdc2; apoptosis; DNA damage; 細胞分裂; DNA障害

The mammalian Chk2 kinase is thought to mediate ATM-dependent signaling in response to DNA damage. The physiological role of mammalian Chk2 has now been investigated by the generation of Chk2-deficient mice. Although Chk2(-/-) mice appeared normal, they were resistant to ionizing radiation (IR) as a result of the preservation of splenic lymphocytes. Thymocytes and neurons of the developing brain were also resistant to IR-induced apoptosis. The IR-induced G(1)/S cell cycle checkpoint, but not the G(2)/M or S phase checkpoints, was impaired in embryonic fibroblasts derived from Chk2(-/-) mice. IR-induced stabilization of p53 in Chk2(-/-)cells was 50-70% of that in wild-type cells. Caffeine further reduced p53 accumulation, suggesting the existence of an ATM/ATR-dependent but Chk2-independent pathway for p53 stabilization. In spite of p53 protein stabilization and phosphorylation of Ser23, p53-dependent transcriptional induction of target genes, such as p21 and Noxa, was not observed in Chk2(-/-) cells. Our results show that Chk2 plays a critical role in p53 function in response to IR by regulating its transcriptional activity as well as its stability.

哺乳动物Chk 2激酶被认为介导响应于DNA损伤的ATM依赖性信号传导。哺乳动物Chk 2的生理作用现在已经通过Chk 2缺陷小鼠的产生来研究。虽然Chk 2（-/-）小鼠表现正常，但由于保留了脾淋巴细胞，它们对电离辐射（IR）具有抵抗力。胸腺细胞和神经元的发育中的大脑也抵抗IR诱导的凋亡。在Chk 2（-/-）小鼠胚胎成纤维细胞中，IR诱导的G（1）/S细胞周期检查点受损，而G（2）/M或S期检查点未受损。IR诱导的Chk 2（-/-）细胞中p53的稳定性是野生型细胞中的50-70%。咖啡因进一步减少p53的积累，这表明存在一个ATM/ATR依赖性，但Chk 2独立的p53稳定途径。尽管p53蛋白的稳定和Ser 23的磷酸化，但在Chk 2（-/-）细胞中未观察到靶基因（如p21和Noxa）的p53依赖性转录诱导。我们的研究结果表明，Chk 2在p53功能中起着至关重要的作用，通过调节其转录活性以及其稳定性，以响应IR。

项目成果

Burgers, P.M.: "Eukaryotic DNA polymerases : proposal for a revised nomenclature"J. Biol. Chem.. 274. 43487-43490 (2001)

Burgers, P.M.：“真核 DNA 聚合酶：修订命名法的提案”J.

Kobayashi, Y.: "Hydrocephalus, situs inversus, Chronic sinusitis, and male infertileity in DNA polymerase lambda-deficient mice : possible implication for the pathogenesis of immotile cilia syndrome"Mol. Cell. Biol.. 22. 2769-2776 (2002)

Kobayashi, Y.：“DNA 聚合酶 lambda 缺陷小鼠的脑积水、内脏逆位、慢性鼻窦炎和男性不育：对不动纤毛综合征发病机制的可能影响”Mol。

Li, S.F.: "Genomic structure and characterization of the promoter region of the human NAK gene"Gene. 304. 57-64 (2003)

Li，S.F.：“人类 NAK 基因启动子区域的基因组结构和特征”基因。

Ishimi, Y: "Identification of MCM4 as a Target of the DNA Replication block Checkpoint System"J. Biol. Chem.. in press.

Ishimi, Y：“鉴定 MCM4 作为 DNA 复制块检查点系统的靶标”J。

Hashimoto, Y.: "Identification and characterization of Nek6 protein kinase, a potential human homolog of NIMA"Biochem, Biophys. Res. Commun.. 293. 753-758 (2002)

Hashimoto, Y.：“Nek6 蛋白激酶（NIMA 的潜在人类同源物）的鉴定和表征”Biochem、Biophys。