Function of high-mobility group A proteins in the DNA damage signaling for the induction of apoptosis.
Function of high-mobility group A proteins in the DNA damage signaling for the induction of apoptosis.
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DOI：
10.1038/srep31714
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发表时间：
2016-08-19
影响因子：
4.6
通讯作者：
Hidaka M
中科院分区：
文献类型：
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作者：
Fujikane R;Komori K;Sekiguchi M;Hidaka M
DNA中产生的O 6-甲基鸟嘌呤可以在DNA复制过程中与胸腺嘧啶配对，从而导致G到A的转换突变。为了防止这种结果，细胞窝藏O 6-甲基鸟嘌呤含有错配进行凋亡，需要错配修复（MMR）蛋白复合物的功能。为了确定参与诱导细胞凋亡的基因，我们进行了基因陷阱诱变，并分离出一个克隆的小鼠细胞表现出增加的抗烷化剂，N-甲基-N-亚硝基脲（MNU）的杀伤作用。该突变体携带Hmga 2基因中的插入，该基因属于编码高迁移率A组非组蛋白染色质蛋白的基因家族。为了阐明HMGA蛋白在细胞凋亡途径中的功能，我们将HMGA 1和/或HMGA 2的siRNA引入O 6-甲基鸟嘌呤-DNA甲基转移酶缺陷的人HeLa MR细胞中。与对照相比，HMGA 1和HMGA 2单敲低细胞显示出对MNU的抗性增加，并且HMGA 1/HMGA 2双敲低细胞显示出进一步增加的耐受性。ATR和CHK 1的磷酸化，亚G1群体的出现，以及caspase-9的活化在敲低细胞中被抑制，尽管错配识别复合物的形成不受影响。这些结果表明，HMGA家族蛋白在O 6-甲基鸟嘌呤引发的细胞凋亡过程中的损伤识别步骤之后发挥作用。
O6-Methylguanine produced in DNA can pair with thymine during DNA replication, thus leading to a G-to-A transition mutation. To prevent such outcomes, cells harboring O6-methylguanine-containing mispair undergo apoptosis that requires the function of mismatch repair (MMR) protein complex. To identify the genes involved in the induction of apoptosis, we performed gene-trap mutagenesis and isolated a clone of mouse cells exhibiting an increased resistance to the killing effect of an alkylating agent, N-methyl-N-nitrosourea (MNU). The mutant carries an insertion in the Hmga2 gene, which belongs to a gene family encoding the high-mobility group A non-histone chromatin proteins. To elucidate the function of HMGA proteins in the apoptosis pathway, we introduced siRNAs for HMGA1 and/or HMGA2 into human HeLa MR cells defective in O6-methylguanine-DNA methyltransferase. HMGA1- and HMGA2-single knockdown cells showed an increased resistance to MNU, and HMGA1/HMGA2-double knockdown cells exhibited further increased tolerance compared to the control. The phosphorylation of ATR and CHK1, the appearance of a sub-G1 population, and caspase-9 activation were suppressed in the knockdown cells, although the formation of mismatch recognition complex was unaffected. These results suggest that HMGA family proteins function at the step following the damage recognition in the process of apoptosis triggered by O6-methylguanine.