Enzymes in the NAD+ Salvage Pathway Regulate SIRT1 Activity at Target Gene Promoters*
Enzymes in the NAD+ Salvage Pathway Regulate SIRT1 Activity at Target Gene Promoters*
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DOI：
10.1074/jbc.m109.016469
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发表时间：
2009-05
期刊：
影响因子：
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通讯作者：
Tong Zhang;Jhoanna G. Berrocal;Kristine M. Frizzell;Matthew J. Gamble;Michelle E. DuMond;Raga Krishnakumar;Tianle Yang;A. Sauve;W. Lee Kraus
中科院分区：
文献类型：
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作者：
Tong Zhang;Jhoanna G. Berrocal;Kristine M. Frizzell;Matthew J. Gamble;Michelle E. DuMond;Raga Krishnakumar;Tianle Yang;A. Sauve;W. Lee Kraus
在哺乳动物中，尼克酰胺磷酸核糖基转移酶（NAMPT）和尼克酰胺单核苷酸腺苷酰转移酶1（NMNAT-1）构成核NAD+补救途径，其调节NAD+依赖性酶如蛋白脱乙酰酶SIRT 1的功能。SIRT 1的主要功能之一是通过修饰染色质相关蛋白来调节靶基因的转录。然而，关于NAD+生物合成酶调节SIRT 1活性以控制细胞核中基因转录的分子机制知之甚少。在这项研究中，我们表明，在MCF-7乳腺癌细胞中，稳定的短发夹RNA介导的NAMPT或NMNAT-1敲低降低了总细胞NAD+水平，并改变了基因表达的整体模式。此外，我们表明SIRT 1在介导NAMPT和NMNAT-1的基因调控作用中起着关键作用。具体来说，我们发现SIRT 1结合到通常由NAMPT，NMNAT-1和SIRT 1调控的基因的启动子上，并且SIRT 1组蛋白脱乙酰酶活性在这些启动子上由NAMPT和NMNAT-1调控。最重要的是，NMNAT-1与SIRT 1相互作用，并被SIRT 1募集到靶基因启动子。总的来说，我们的研究结果揭示了一个机制，直接控制SIRT 1脱乙酰酶活性在一组靶基因启动子的NMNAT-1。这种机制与NAMPT依赖的核NAD+产生调节协同作用，建立了NAD+转录调节的重要途径。
In mammals, nic o tin a mide phosphoribosyltransferase (NAMPT) and nic o tin a mide mononucleotide ad en y lyltransferase 1 (NMNAT-1) constitute a nuclear NAD+ salvage pathway which regulates the functions of NAD+-de pend ent enzymes such as the protein deacetylase SIRT1. One of the major functions of SIRT1 is to regulate target gene transcription through modification of chromatin-associated proteins. However, little is known about the molecular mechanisms by which NAD+ biosynthetic enzymes regulate SIRT1 activity to control gene transcription in the nucleus. In this study we show that stable short hairpin RNA-mediated knockdown of NAMPT or NMNAT-1 in MCF-7 breast cancer cells reduces total cellular NAD+ levels and alters global patterns of gene expression. Furthermore, we show that SIRT1 plays a key role in mediating the gene regulatory effects of NAMPT and NMNAT-1. Specifically, we found that SIRT1 binds to the promoters of genes commonly regulated by NAMPT, NMNAT-1, and SIRT1 and that SIRT1 histone deacetylase activity is regulated by NAMPT and NMNAT-1 at these promoters. Most significantly, NMNAT-1 interacts with, and is recruited to target gene promoters by SIRT1. Collectively, our results reveal a mechanism for the direct control of SIRT1 deacetylase activity at a set of target gene promoters by NMNAT-1. This mechanism, in collaboration with NAMPT-de pend ent regulation of nuclear NAD+ production, establishes an important pathway for transcription regulation by NAD+.