Sirtuin 1 Functionally and Physically Interacts with Disruptor of Telomeric Silencing-1 to Regulate α-ENaC Transcription in Collecting Duct
Sirtuin 1 Functionally and Physically Interacts with Disruptor of Telomeric Silencing-1 to Regulate α-ENaC Transcription in Collecting Duct
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DOI：
10.1074/jbc.m109.020073
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发表时间：
2009-07-31
影响因子：
4.8
通讯作者：
Kone, Bruce C.
中科院分区：
文献类型：
--
作者：
Zhang, Dongyu;Li, Shiyu;Kone, Bruce C.
醛固酮通过增加集合管主细胞顶膜中表达的上皮Na+通道α-亚单位（α-ENaC）的转录，在很大程度上增加肾小管Na+吸收。我们最近报道了含有端粒沉默-1（Dot 1）的组蛋白H3 K79甲基转移酶破坏物的复合物与小鼠内髓集合管mIMCD 3细胞中的α-ENaC启动子相关并抑制该启动子，并且醛固酮起到破坏该复合物及其抑制作用的作用（Zhang，W.，Xia，X.，Reisenauer，M. R.，Rieg，T.，Lang，F.，Kuhl，D.，Vallon，V.，和Kone，B. C.等人（2007）J. Clin. Invest. 117，773-783）。在这里，我们证明了NAD（+）-依赖性脱乙酰酶sirtuin 1（Sirt 1）功能和物理相互作用与Dot 1，以提高H3 K79甲基化的Dot 1的分布活性，从而抑制a-ENaC在mIMCD 3细胞的转录。令人惊讶的是，Sirt 1过表达以脱乙酰酶非依赖性方式抑制了基础α-ENaC mRNA表达和α-ENaC启动子活性。Sirt 1抑制α-ENaC转录的能力保留在仅表达其N-末端结构域的截短Sirt 1构建体中。相反，Sirt 1敲除增强了α-ENaC mRNA水平和α-ENaC启动子活性，并抑制了与α-ENaC启动子相关的染色质中的H3 K79甲基化，特别是H3 K79三甲基化。Sirt 1和Dot 1共免疫沉淀的mIMCD 3细胞和共定位在细胞核中。Sirt 1从与已知与Dot 1相关的α-ENaC启动子区域相关的染色质中免疫沉淀。醛固酮抑制Sirt 1在其中两个区域的结合以及Sirt 1 mRNA的表达，与诱导alpha-ENaC转录的方式协调。过表达的Sirt 1抑制醛固酮对alpha-ENaC转录的诱导，而不依赖于盐皮质激素受体反式激活的影响。这些数据将Sirt 1鉴定为α-ENaC、Dot 1和醛固酮信号通路的新型调节剂。
Aldosterone increases renal tubular Na+ absorption in large part by increasing transcription of the epithelial Na+ channel alpha-subunit (alpha-ENaC) expressed in the apical membrane of collecting duct principal cells. We recently reported that a complex containing the histone H3K79 methyltransferase disruptor of telomeric silencing-1 (Dot1) associates with and represses the alpha-ENaC promoter in mouse inner medullary collecting duct mIMCD3 cells, and that aldosterone acts to disrupt this complex and its inhibitory effects (Zhang, W., Xia, X., Reisenauer, M. R., Rieg, T., Lang, F., Kuhl, D., Vallon, V., and Kone, B. C. ( 2007) J. Clin. Invest. 117, 773-783). Here we demonstrate that the NAD(+)-dependent deacetylase sirtuin 1 (Sirt1) functionally and physically interacts with Dot1 to enhance the distributive activity of Dot1 on H3K79 methylation and thereby represses alpha-ENaC transcription in mIMCD3 cells. Sirt1 overexpression inhibited basal alpha-ENaC mRNA expression and alpha-ENaC promoter activity, surprisingly in a deacetylase-independent manner. The ability of Sirt1 to inhibit alpha-ENaC transcription was retained in a truncated Sirt1 construct expressing only its N-terminal domain. Conversely, Sirt1 knockdown enhanced alpha-ENaC mRNA levels and alpha-ENaC promoter activity, and inhibited global H3K79 methylation, particularly H3K79 trimethylation, in chromatin associated with the alpha-ENaC promoter. Sirt1 and Dot1 co-immunoprecipitated from mIMCD3 cells and colocalized in the nucleus. Sirt1 immunoprecipitated from chromatin associated with regions of the alpha-ENaC promoter known to associate with Dot1. Aldosterone inhibited Sirt1 association at two of these regions, as well as Sirt1 mRNA expression, in a coordinate manner with induction of alpha-ENaC transcription. Overexpressed Sirt1 inhibited aldosterone induction of alpha-ENaC transcription independent of effects on mineralocorticoid receptor trans-activation. These data identify Sirt1 as a novel modulator of alpha-ENaC, Dot1, and the aldosterone signaling pathway.