Enzymes in the NAD+ salvage pathway regulate SIRT1 activity at target gene promoters.
In mammals, nicotinamide phosphoribosyltransferase (NAMPT) and nicotinamide mononucleotide adenylyltransferase 1 (NMNAT-1) constitute a nuclear NAD(+) salvage pathway which regulates the functions of NAD(+)-dependent 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-dependent regulation of nuclear NAD(+) production, establishes an important pathway for transcription regulation by NAD(+).
Zhang
Tong
T
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
Berrocal
Jhoanna G
JG
Frizzell
Kristine M
KM
Gamble
Matthew J
MJ
DuMond
Michelle E
ME
Krishnakumar
Raga
R
Yang
Tianle
T
Sauve
Anthony A
AA
Kraus
W Lee
WL
D000818:Animals; D045744:Cell Line, Tumor; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D009243:NAD / Q000378:metabolism*; D054409:Nicotinamide Phosphoribosyltransferase / Q000235:genetics* / Q000378:metabolism*; D009612:Nicotinamide-Nucleotide Adenylyltransferase / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D056564:Sirtuin 1; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism*
D016207:Cytokines; D009243:NAD; D054409:Nicotinamide Phosphoribosyltransferase; C085455:nicotinamide phosphoribosyltransferase, human; C484007:NMNAT1 protein, human; D009612:Nicotinamide-Nucleotide Adenylyltransferase; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1; D037761:Sirtuins