Morris-Blanco Kahlilia C, Chokkalla Anil K, Bertogliat Mario J, Vemuganti Raghu
Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA.
Department of Research, William S. Middleton Veterans Administration Hospital, Madison, WI, USA.
J Cereb Blood Flow Metab. 2021 Mar;41(3):590-603. doi: 10.1177/0271678X20912965. Epub 2020 May 7.
The 5-hydroxymethylcytosine (5hmC) epigenetic modification is highly enriched in the CNS and a critical modulator of neuronal function and development. We found that cortical 5hmC was enhanced from 5 min to three days of reperfusion following focal ischemia in adult mice. Blockade of the 5hmC-producing enzyme ten-eleven translocase 3 (TET3) increased edema, infarct volume, and motor function impairments. To determine the mechanism by which TET3 provides ischemic neuroprotection, we assessed the genomic regions where TET3 modulates 5hmC. Genome-wide sequencing analysis of differentially hydroxymethylated regions (DhMRs) revealed that focal ischemia robustly increased 5hmC at the promoters of thousands of genes in a TET3-dependent manner. TET3 inhibition reduced 5hmC at the promoters of neuroprotective genes involved in cell survival, angiogenesis, neurogenesis, antioxidant defense, DNA repair, and metabolism demonstrating a role for TET3 in endogenous protection against stroke. The mRNA expression of several genes with known involvement in ischemic neuroprotection were also reduced with TET3 knockdown in both male and female mice, establishing a correlation between decreased promoter 5hmC levels and decreased gene expression. Collectively, our results indicate that TET3 globally increases 5hmC at regulatory regions and overwhelmingly modulates 5hmC in several neuroprotective pathways that may improve outcome after ischemic injury.
5-羟甲基胞嘧啶（5hmC）表观遗传修饰在中枢神经系统中高度富集，是神经元功能和发育的关键调节因子。我们发现，成年小鼠局灶性缺血再灌注后5分钟至三天，皮质5hmC增强。阻断产生5hmC的酶——10-11易位酶3（TET3）会增加水肿、梗死体积和运动功能障碍。为了确定TET3提供缺血性神经保护的机制，我们评估了TET3调节5hmC的基因组区域。对差异羟甲基化区域（DhMRs）的全基因组测序分析表明，局灶性缺血以TET3依赖的方式显著增加了数千个基因启动子处的5hmC。TET3抑制降低了参与细胞存活、血管生成、神经发生、抗氧化防御、DNA修复和代谢的神经保护基因启动子处的5hmC，表明TET3在内源性中风保护中发挥作用。在雄性和雌性小鼠中，TET3基因敲低也降低了几种已知参与缺血性神经保护的基因的mRNA表达，建立了启动子5hmC水平降低与基因表达降低之间的相关性。总的来说，我们的结果表明，TET3在全局上增加了调控区域的5hmC，并在几种可能改善缺血性损伤后结局的神经保护途径中压倒性地调节5hmC。
