Abstract
Abstract in English, Chinese DNA2, a multifunctional enzyme with structure-specific nuclease, 5 '-to-3 ' helicase, and DNA-dependent ATPase activities, plays a pivotal role in the cellular response to DNA damage. However, its involvement in cerebral ischemia/reperfusion (I/R) injury remains to be elucidated. This study investigated the involvement of DNA2 in cerebral I/R injury using conditional knockout (cKO) mice ( Nestin-Cre) subjected to middle cerebral artery occlusion (MCAO), an established model of cerebral I/R. Results demonstrated a gradual up-regulation of DNA2 expression, peaking at 72 h post-MCAO. Notably, DNA2 cKO mice exhibited more pronounced brain injury, neurological deficits, and neuronal apoptosis within the penumbra following MCAO. Additionally, DNA2 expression was elevated in an oxygen-glucose deprivation/reoxygenation (OGD/R) cell culture model, and DNA2 knockdown (KD) exacerbated neuronal apoptosis and oxidative stress. Transcriptome analysis of ischemic penumbra tissues via RNA sequencing revealed significant down-regulation of Homer1 in DNA2 cKO mice. Furthermore, in vitro experiments demonstrated that overexpression of Homer1a ameliorated DNA2 KD-induced neuronal apoptosis. Collectively, these findings demonstrate that DNA2 deficiency exacerbates cerebral I/R injury through the down-regulation of Homer1a, highlighting a novel regulatory axis in ischemic neuroprotection. DNA2是一种多功能酶，在冈崎片段加工、端粒维护、DNA双链断裂修复以及DNA复制叉处理等过程中发挥关键作用，对基因组稳定性至关重要。然而，DNA2在脑缺血/再灌注（Ischemia/reperfusion，I/R）损伤中的作用尚未明确。该研究利用 DNA2条件性敲除（Conditional knockout，cKO）小鼠，通过建立大脑中动脉闭塞（Middle cerebral artery occlusion，MCAO）模型探讨其功能。结果显示，MCAO后DNA2表达逐渐上调，并在72小时达到峰值。值得注意的是，cKO小鼠在MCAO后表现出显著的神经功能缺损和半暗带神经元凋亡。此外，在氧糖剥夺/复氧（Oxygen-glucose deprivation/reoxygenation，OGD/R）细胞模型中， DNA2敲低（Knockdown，KD）加剧了神经元凋亡和氧化应激反应。为进一步探究 DNA2在脑I/R损伤中的机制，我们对缺血半暗带组织进行了全转录组测序（Transcriptome sequencing，RNA-seq），结果发现，cKO小鼠的 Homer1表达显著下调。此外， Homer1a过表达能够改善 DNA2 KD引起的神经元凋亡。综上所述，该研究表明， DNA2敲除通过下调 Homer1a表达加剧脑I/R损伤。.