Cytosolic accumulation of γH2AX is associated with tropomyosin-related kinase A-induced cell death in U2OS cells
Cytosolic accumulation of γH2AX is associated with tropomyosin-related kinase A-induced cell death in U2OS cells
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DOI：
10.3858/emm.2008.40.3.276
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发表时间：
2008-06-30
影响因子：
12.8
通讯作者：
Kim, Deok Ryong
中科院分区：
文献类型：
--
作者：
Jung, Eun Joo;Kim, Choong Won;Kim, Deok Ryong
原肌球蛋白相关激酶A（TrkA）在各种神经元和非神经元细胞类型的细胞存活、分化和凋亡中起重要作用。在这里，我们表明，TrkA过表达的Tet-On系统模仿神经生长因子（NGF）刺激的情况下，在U2 OS细胞中的NGF介导的激活途径。此外，p53上调DNA损伤后，抑制TrkA，和p21上调TrkA在p53非依赖性的方式。TrkA过表达通过中断细胞周期进程引起细胞死亡，并且TrkA诱导的细胞死亡在其特异性抑制剂GW 441756的存在下减少。有趣的是，在不存在DNA损伤诱导剂的情况下，TrkA介导的细胞死亡与γ H2 AX产生和聚（ADP-核糖）聚合酶切割密切相关。在这项研究中，我们还发现TrkA产生γ H2 AX被TrkA激酶抑制剂K-252 a和GW 441756阻断，并且它也被JNK抑制剂SP 600125显著抑制。此外，TrkA引起的细胞活力降低被SP 600125处理强烈抑制，表明JNK在TrkA诱导的细胞死亡中起关键作用。我们还发现，γ H2 AX和TrkA共定位在细胞质中的DNA损伤的情况下，和核定位的γ H2 AX诱导的DNA损伤的TrkA过表达部分改变到细胞质。我们的研究结果表明，γ H2 AX的异常胞质积累涉及在没有DNA损伤的情况下TrkA诱导的细胞死亡。
Tropomyosin-related kinase A (TrkA) plays an important role in cell survival, differentiation, and apoptosis in various neuronal and nonneuronal cell types. Here we show that TrkA overexpression by the Tet-On system mimics NGF-mediated activation pathways in the absence of nerve growth factor (NGF) stimulation in U2OS cells. In addition, p53 upregulation upon DNA damage was inhibited by TrkA, and p21 was upregulated by TrkA in a p53-independent manner. TrkA overexpression caused cell death by interrupting cell cycle progression, and TrkA-induced cell death was diminished in the presence of its specific inhibitor GW441756. Interestingly, TrkA-mediated cell death was strongly related to gamma H2AX production and poly (ADP-ribose) polymerase cleavage in the absence of DNA damage inducer. In this study, we also reveal that gamma H2AX production by TrkA is blocked by TrkA kinase inhibitors K-252a and GW441756, and it is also significantly inhibited by JNK inhibitor SP600125. Moreover, reduction of cell viability by TrkA was strongly suppressed by SP600125 treatment, suggesting a critical role of JNK in TrkA-induced cell death. We also found that gamma H2AX and TrkA were colocalized in cytosol in the absence of DNA damage, and the nuclear localization of gamma H2AX induced by DNA damage was partly altered to cytosol by TrkA overexpression. Our results suggest that the abnormal cytosolic accumulation of gamma H2AX is implicated in TrkA-induced cell death in the absence of DNA damage.