Ezh2 Inhibits Replicative Senescence of Atrial Fibroblasts Through Promotion of H3K27me3 in the Promoter Regions of CDKN2a and Timp4 Genes.
Ezh2 Inhibits Replicative Senescence of Atrial Fibroblasts Through Promotion of H3K27me3 in the Promoter Regions of CDKN2a and Timp4 Genes.
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Ezh2 通过促进 CDKN2a 和 Timp4 基因启动子区的 H3K27me3 抑制心房成纤维细胞的复制衰老
DOI：
10.2147/jir.s374951
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发表时间：
2022
影响因子：
4.5
通讯作者：
中科院分区：
文献类型：
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在大多数细胞类型中，复制性衰老（RS）被认为是衰老的主要原因。心房纤维化的病理特征是心房成纤维细胞（AF）增殖和细胞外基质蛋白过度积聚，是老年人心房颤动（Afib）最常见的基质。然而，房颤RS是否发生在老年和纤维化的左心房（LA），如果是的话，什么是房颤RS发病机制的关键调节因子仍然是未知的。我们从年轻（6-8周龄）和老年（24月龄）C57 BL/6雄性小鼠获得左心房组织。使用RNA-seq结果的比较分析进行差异基因的筛选和验证。细胞传代后，在原代AF中检查复制衰老。进一步进行功能获得和功能丧失实验，以探讨AF RS进展的调节。在本研究中，我们证明了在老年和纤维化的LA中存在相当程度的AF ' RS。转录组筛选显示，Ezh 2（增强子zeste同源物2）在老年小鼠的LA组织中显著下调。Ezh 2是一种组蛋白甲基转移酶，催化H3 K27 me 3并介导转录沉默。我们证实Ezh 2在分离的纯衰老AF中下调。通过siRNA敲低Ezh 2或GSK-126和GSK-343抑制Ezh 2甲基转移酶活性可加速AF早期传代中的RS，而其过表达可减缓AF晚期传代中的RS。在机制上，Ezh 2通过在其启动子区形成典型的H3 K27 me 3修饰来抑制CDKN 2a（p16，p19）和Timp 4基因的转录。此外，AF中TIMP 4和MMP 8之间的功能平衡可能会因Ezh 2表达的变化而崩溃。因此，这些结果表明Ezh 2是AF ' RS的关键调节因子，并且这项工作可能为老年人心房纤维化的未来治疗提供基础。
In most cell types, replicative senescence (RS) is supposed to be a principle causative factor for aging. Atrial fibrosis, pathologically characterized by proliferation of atrial fibroblasts (AFs) and excessive accumulation of extracellular matrix proteins, is the most common substrate of atrial fibrillation (Afib) in the elderly. However, whether AFs’ RS develops in the aged and fibrotic left atrium (LA) and, if yes, what is the key regulator for the pathogenesis of AFs’ RS remain largely unknown. We obtained the left atrial tissues from young (6–8 weeks old) and aged (24 months old) C57BL/6 male mice. Screening and validation of differential genes were performed using comparative analysis of RNA-seq results. Replicative senescence was examined in primary AFs after cell passage. Further gain-of-function and loss-of-function experiments were performed to explore the regulation of the AFs’ RS progression. In the present study, we demonstrated that there was a considerable extent of AFs’ RS in the aged and fibrotic LA. Transcriptome screening showed that Ezh2 (Enhancer of zeste homolog 2) was significantly downregulated in the LA tissue of aged mice. Ezh2 is a histone methyltransferase that catalyzes H3K27me3 and mediates transcriptional silencing. We confirmed that Ezh2 was downregulated in the isolated pure senescent AFs. Knockdown of Ezh2 by siRNA or inhibition of Ezh2ʹs methyltransferase activities by GSK-126 and GSK-343 accelerated RS in the early passage of AFs, while its overexpression deaccelerated RS in the late passage of AFs. Mechanistically, Ezh2 suppressed CDKN2a (p16, p19) and Timp4 gene transcription by forming canonical H3K27me3 modifications in their promoter regions. Furthermore, the functional balance between Timp4 and MMP8 in AFs could be collapsed by changes in Ezh2 expression. These results thus indicate that Ezh2 is a key regulator of AFs’ RS and this work may provide a basis for future treatments for atrial fibrosis in the elderly.