Induction and inhibition of the pan-nuclear gamma-H2AX response in resting human peripheral blood lymphocytes after X-ray irradiation.
Induction and inhibition of the pan-nuclear gamma-H2AX response in resting human peripheral blood lymphocytes after X-ray irradiation.
复制标题
X射线照射后静息人外周血淋巴细胞全核γ-H2AX反应的诱导和抑制
DOI：
10.1038/cddiscovery.2016.11
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发表时间：
2016
影响因子：
7
通讯作者：
Chen H
中科院分区：
文献类型：
--
作者：
Ding D;Zhang Y;Wang J;Zhang X;Gao Y;Yin L;Li Q;Li J;Chen H
人外周血淋巴细胞（hbls）是人体内对电离辐射（IR）最敏感的细胞之一，而IR引起的hbls DNA损伤和功能损伤是电离辐射事故的不良后果，也是放疗的主要副作用。磷酸化的H2AX （γH2AX）是DNA双链断裂的敏感标记物，但IR后泛核γH2AX反应在hbls中的作用和调控尚不清楚。我们在此证明了泛核γ - h2ax信号以时间和剂量依赖的方式增加，与> - 94%的TUNEL凋亡染色共定位，并且在低LET x射线IR后静息的hbls中表现出典型的凋亡模式。此外，x辐射诱导的泛核p-ATM和p-DNA-PKcs反应也发生在静止的hbls中，分别与92-95%的TUNEL染色和97-98%的泛核γ - h2ax信号共定位，在照射后6 h达到最大值，但在照射后24 h消失。此外，ATM/DNA-PKcs抑制剂KU55933、p53抑制剂PFT-μ和泛caspase抑制剂ZVAD-fmk显著降低x照射诱导的泛核γ - h2ax信号和TUNEL染色，保护hbls免于凋亡，但降低x照射下hbls对丝裂原的增殖反应。值得注意的是，KU55933和PFT-μ通过抑制p-ATM、p-DNA-PKcs和γ - h2ax灶的形成，增加了ir诱导的染色体断裂和错误修复事件，而ZVAD-fmk没有增加ir诱导的染色体不稳定性。综上所述，我们的数据表明，泛核γ - h2ax反应是一种凋亡信号，是由瞬时泛核ATM和DNA-PKcs激活触发的，在x照射的hbls中，p53和泛caspase介导，caspase抑制剂比ATM/DNA-PKcs抑制剂和p53抑制剂更能阻断泛核γ - h2ax反应/凋亡，保护hbls免受IR伤害。
Human peripheral blood lymphocytes (HPBLs) are one of the most sensitive cells to ionizing radiation (IR) in the human body, and IR-induced DNA damage and functional impairment of HPBLs are the adverse consequences of IR accidents and major side effects of radiotherapy. Phosphorylated H2AX (γH2AX) is a sensitive marker for DNA double-strand breaks, but the role and regulation of the pan-nuclear γH2AX response in HPBLs after IR remain unclear. We herein demonstrated that the pan-nuclear γH2AX signals were increased in a time-and dose-dependent manner, colocalized with> 94% of TUNEL apoptotic staining, and displayed a typical apoptotic pattern in resting HPBLs after low LET X-ray IR. In addition, the X-irradiation-induced pan-nuclear p-ATM and p-DNA-PKcs responses also occurred in resting HPBLs, and were colocalized with 92–95% of TUNEL staining and 97–98% of the pan-nuclear γH2AX signals, respectively, with a maximum at 6 h post irradiation, but disappeared at 24 h post irradiation. Moreover, ATM/DNA-PKcs inhibitor KU55933, p53 inhibitor PFT-μ and pan-caspase inhibitor ZVAD-fmk significantly decreased X-irradiation-induced pan-nuclear γH2AX signals and TUNEL staining, protected HPBLs from apoptosis, but decreased the proliferative response to mitogen in X-irradiated HPBLs. Notably, whereas both KU55933 and PFT-μ increased the IR-induced chromosome breaks and mis-repair events through inhibiting the formation of p-ATM, p-DNA-PKcs and γH2AX foci in X-irradiated HPBLs, the ZVAD-fmk did not increase the IR-induced chromosomal instability. Taken together, our data indicate that pan-nuclear γH2AX response represents an apoptotic signal that is triggered by the transient pan-nuclear ATM and DNA-PKcs activation, and mediated by p53 and pan-caspases in X-irradiated HPBLs, and that caspase inhibitors are better than ATM/DNA-PKcs inhibitors and p53 inhibitors to block pan-nuclear γH2AX response/apoptosis and protect HPBLs from IR.