Institute of Cardiovascular Regeneration, Internal Medicine III, University of Frankfurt, Germany.
Circ Res. 2011 Nov 11;109(11):1219-29. doi: 10.1161/CIRCRESAHA.111.247304. Epub 2011 Oct 6.
Proangiogenic hematopoietic and endothelial progenitor cells (EPCs) contribute to postnatal neovascularization, but the mechanisms regulating differentiation to the endothelial lineage are unclear.
To elucidate the epigenetic control of endothelial gene expression in proangiogenic cells and EPCs.
Here we demonstrate that the endothelial nitric oxide synthase (eNOS) promoter is epigenetically silenced in proangiogenic cells (early EPCs), CD34(+) cells, and mesoangioblasts by DNA methylation and prominent repressive histone H3K27me3 marks. In order to reverse epigenetic silencing to facilitate endothelial commitment, we used 3-deazaneplanocin A, which inhibits the histone methyltransferase enhancer of zest homolog 2 and, thereby, reduces H3K27me3. 3-Deazaneplanocin A was not sufficient to increase eNOS expression, but the combination of 3-deazaneplanocin A and the histone deacetylase inhibitor Trichostatin A augmented eNOS expression, indicating that the concomitant inhibition of silencing histone modification and enhancement of activating histone modification facilitates eNOS expression. In ischemic tissue, hypoxia plays a role in recruiting progenitor cells. Therefore, we examined the effect of hypoxia on epigenetic modifications. Hypoxia modulated the balance of repressive to active histone marks and increased eNOS mRNA expression. The reduction of repressive H3K27me3 was associated with an increase of the histone demethylase Jmjd3. Silencing of Jmjd3 induced apoptosis and senescence in proangiogenic cells and inhibited hypoxia-mediated up-regulation of eNOS expression in mesoangioblasts.
These findings provide evidence that histone modifications epigenetically control the eNOS promoter in proangiogenic cells.
促血管生成的造血和内皮祖细胞（EPC）有助于出生后的新血管生成，但调节向内皮谱系分化的机制尚不清楚。
阐明促血管生成细胞和 EPC 中内皮基因表达的表观遗传控制。
我们在此证明，内皮型一氧化氮合酶（eNOS）启动子在促血管生成细胞（早期 EPC）、CD34+细胞和成肌细胞中通过 DNA 甲基化和明显的抑制性组蛋白 H3K27me3 标记被表观遗传沉默。为了逆转表观遗传沉默以促进内皮细胞的定向分化，我们使用了 3-去氮杂胞苷 A，它抑制组蛋白甲基转移酶增强子的同系物 2，从而减少 H3K27me3。3-去氮杂胞苷 A不足以增加 eNOS 的表达，但 3-去氮杂胞苷 A 和组蛋白去乙酰化酶抑制剂 Trichostatin A 的组合增强了 eNOS 的表达，表明同时抑制沉默的组蛋白修饰和增强激活的组蛋白修饰促进了 eNOS 的表达。在缺血组织中，缺氧在募集祖细胞中起作用。因此，我们研究了缺氧对表观遗传修饰的影响。缺氧调节了抑制性和激活性组蛋白标记的平衡，并增加了 eNOS mRNA 的表达。抑制性 H3K27me3 的减少与组蛋白去甲基酶 Jmjd3 的增加有关。促血管生成细胞中 Jmjd3 的沉默诱导细胞凋亡和衰老，并抑制成肌细胞中缺氧介导的 eNOS 表达上调。
这些发现为组蛋白修饰在促血管生成细胞中表观遗传控制 eNOS 启动子提供了证据。
