BACKGROUND The Sirtuin family is widely distributed from archaea and eubacteria to eukaryotes and seven different homologous proteins are found in the humans that show a central highly conserved region, defined as the catalytic core. In comparison to other proteins of the family, SIRT1 presents two large regions, i.e. the amino and carboxyl terminals that are missing in all the other sirtuins. SIRT1 is a NAD+-dependent deacetylase closely related to yeast Sir2, the first gene discovered in sirtuin family, which has NAD+ dependent class III histone deacetylase activity. Sites of phosphorylation and SUMOylation consensus were recently found also in the amino- and in carboxyl-terminal regions, and these were proposed having regulation and localization functions.1
Experimental data support the SIRT1 implication in processes including chromatin remodelling, transcriptional silencing, chromosomal stability, cell cycle progression, apoptosis, autophagy, metabolism, growth suppression, inflammation, and stress response. In fact, the SIRT1 regulation activity occurs through the deacetylation reaction of various and different substrates such as p53, forkhead box class O (FOXO) transcription factors, peroxisome proliferator activated receptor (PPAR)g co-activator 1a (PGC-1α), nuclear factor (NF)-kB and others, which are closely linked to some age-related diseases. Also SIRT1 stimulates eNOS activity and increases the endothelial NO. Moreover, it was seen that SIRT1 is a negative modulator of adipogenesis by docking with the nuclear receptor co-repressor (NcoR) and induces a decrease of pro-inflammatory cytokine release and a promotion of carcinogenesis by the negative control of Nuclear factor-kB (NF-kB). Because SIRT1 deacetylates non histone proteins, including various transcription factors, it is involved in the control of important biological mechanisms. Through its catalytic activity, it exhibits diversified functions in cell type-specific manner, which have pathophysiological implications in cancer, obesity, inflammation and neurodegenerative diseases. Its modulation leads an increase in mitochondrial biogenesis, and an improvement of glucose metabolism in mitochondria but also in skeletal muscle and adipose tissues. In yeast, Sir2 participates in heterochromatic silencing at mating-type loci. Sir2 extends the life span of yeast by suppressing recombination in the rDNA region and consequently reducing the formation of extrachromosomal rDNA circles, a cause of senescence. Caloric restriction extends the life span in organisms ranging from yeast to mammals, and the Sir2 family plays an essential role in this effect.2 In addition, the neuronal protection effect of SIRT1 may be independent of its enzyme activity.3
Because SIRT1 deacetylates histones and various transcription factors, its subcellular localization must affect its function. It has been demonstrated that the subcellular localization of SIRT1 differs in various tissues and cells. Differentiation affects the cellular distribution of SIRT1 in cardiomyocytes. Additionally, PI-3 kinase-Akt pathway affects the subcellular localization of SIRT1. It was also found that novel co-activators of SIRT1 such as AROS and HIC1 and a co-repressor, DBC1, promote or inhibit SIRT1-mediated deacetylation of its targets. Moreover, it was shown that phosphorylation by cell cycle dependent kinases may be a major mechanism controlling the level and function of SIRT1.4 Also human SIRT1 was phosphorylated by JNK1 on three sites: Ser27, Ser47, and Thr530 and this phosphorylation of SIRT1 increased its nuclear localization and enzymatic activity.5
1. Haigis, M.C. & Guarente,L.P.: Gene Dev. 20:2913-21, 2006
2. Brooks, C.L. & Gu, W.: Nature Rev. Cancer 9:123-8, 2009
3. Pfister,J.A. et al: PLoS ONE 3:e4090, 2008
4. Sasaki, T. et al: PLoS ONE 3:e4020, 2008
5. Nasrin, N. et al: PLoS ONE 4:e8414, 2009
Products are for research use only. They are not intended for human, animal, or diagnostic applications.
Purified recombinant human SIRT1/Sir2 fragments expressed in E. coli.
Species & predicted
reactivity ( ):
Human, Mouse, Rat
IHC 1:50 - 1:200
ICC 1:50 - 1:200
FACS 1:50 - 1:200
Weight of protein:
Detects SIRT1/Sir2 proteins without cross-reactivity with other related proteins.
Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles.
*Optimal working dilutions must be determined by end user.