As a member of the Sirtuins family in mammals, SIRT7 locates in nucleus and is a highly specific H3K18Ac (acetylated lysine 18 of histone H3) deacetylase. Recent studies showed that SIRT7 could participate in the ribosomal RNA transcription, cell metabolism, cell stress and DNA damage repair through various signaling pathways. In addition, SIRT7 is also closely related with aging, heart disease and fatty liver. In particular, SIRT7 plays important roles in the regulation of initiation and development of various tumors, such as liver cancer, gastric cancer, breast cancer, bladder cancer, colorectal cancer, and head/neck squamous cell carcinoma. This review describes the cellular and molecular functions of SIRT7, and systematically summarizes recent progress of SIRT7 in human disease.
Animals ; Histones ; Humans ; Lysine ; Neoplasms ; Signal Transduction ; Sirtuins ; metabolism

Animals ; Bacterial Infections/metabolism* ; Glucose/metabolism* ; Homeostasis ; Insulin Secretion ; Mice ; Mice, Knockout ; Sirtuins/metabolism*

Ketone bodies have beneficial metabolic activities, and the induction of plasma ketone bodies is a health promotion strategy. Dietary supplementation of sodium butyrate (SB) is an effective approach in the induction of plasma ketone bodies. However, the cellular and molecular mechanisms are unknown. In this study, SB was found to enhance the catalytic activity of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a rate-limiting enzyme in ketogenesis, to promote ketone body production in hepatocytes. SB administrated by gavage or intraperitoneal injection significantly induced blood ß-hydroxybutyrate (BHB) in mice. BHB production was induced in the primary hepatocytes by SB. Protein succinylation was altered by SB in the liver tissues with down-regulation in 58 proteins and up-regulation in 26 proteins in the proteomics analysis. However, the alteration was mostly observed in mitochondrial proteins with 41% down- and 65% up-regulation, respectively. Succinylation status of HMGCS2 protein was altered by a reduction at two sites (K221 and K358) without a change in the protein level. The SB effect was significantly reduced by a SIRT5 inhibitor and in Sirt5-KO mice. The data suggests that SB activated HMGCS2 through SIRT5-mediated desuccinylation for ketone body production by the liver. The effect was not associated with an elevation in NAD⁺/NADH ratio according to our metabolomics analysis. The data provide a novel molecular mechanism for SB activity in the induction of ketone body production.
Mice ; Animals ; Butyric Acid/metabolism* ; Ketone Bodies/metabolism* ; Liver/metabolism* ; Hydroxybutyrates/metabolism* ; Down-Regulation ; Sirtuins/metabolism* ; Hydroxymethylglutaryl-CoA Synthase/metabolism*

Circadian clocks regulate behavioral, physiological and biochemical processes in a day/night cycle. Circadian oscillators have an essential role in the coordination of physiological processes with the cyclic changes in the physical environment. Such mammalian circadian clocks composed of the positive components (BMAL1 and CLOCK) and the negative components (CRY and PERIOD (PER)) are regulated by a negative transcriptional feedback loop in which PER is rate-limiting for feedback inhibition. In addition, posttranslational modification of these components is critical for setting or resetting the circadian oscillation. Circadian regulation of metabolism is mediated through reciprocal signaling between the clock and metabolic regulatory networks. AMP-activated protein kinase (AMPK) in the brain and peripheral tissue is a crucial cellular energy sensor that has a role in metabolic control. AMPK-mediated phosphorylation of CRY and Casein kinases I regulates the negative feedback control of circadian clock by proteolytic degradation. AMPK can also modulate the circadian rhythms through nicotinamide adenine dinucleotide-dependent regulation of silent information regulator 1. Growing evidence elucidates the AMPK-mediated controls of circadian clock in metabolic diseases such as obesity and diabetes. In this review, we summarize the current comprehension of AMPK-mediated regulation of the circadian rhythms. This will provide insight into understanding how their components regulate the metabolism.
AMP-Activated Protein Kinases/*metabolism ; Animals ; Casein Kinase I/metabolism ; *Circadian Clocks ; Cryptochromes/metabolism ; Humans ; *Metabolism ; Sirtuins/metabolism

As a member of the sirtuins family, also called Class III histone deacetylases (HDACs), SIRT6 has many catalytic enzyme activities and plays a pivotal role in biological processes including anti-aging, chromatin regulation, transcriptional control, glucose and lipid metabolism, and DNA damage repair. Recently, increasing evidences indicated that SIRT6 was related to initiation and development of tumors, such as hepatic cancer, lung cancer, breast cancer and genital system tumors. However, SIRT6 might play a dual role in tumorigenesis and progression. SIRT6 often acted as a tumor suppressor, but might play an oncogenic role. Based on our current study, we depicted the essential roles of SIRT6 in the initiation and progression of various tumors, and summarized its mode of actions, which might provide clues for cancer therapy.
Carcinogenesis ; Gene Expression Regulation, Neoplastic ; Genes, Tumor Suppressor ; Humans ; Neoplasms ; genetics ; pathology ; Oncogenes ; Sirtuins ; genetics ; metabolism

SIRT6, a member of the silencing information regulatory protein family, is a nicotinamide adenine dinucleotide-dependent histone deacetylase and an ADP-ribose transferase enzyme. It plays an important role in fundamental physiological and pathological processes, including lipid metabolism, inflammation, oxidative stress and fibrosis, and is considered as a potential therapeutic target for metabolic syndrome. SIRT6 knockout mice displayed severe fatty liver, and the expression of SIRT6 in the liver of nonalcoholic steatohepatitis (NASH) mice was significantly lower than that of normal mice. Overexpression of SIRT6 significantly ameliorated NASH-induced liver damage. It is suggested that SIRT6 may play a key role in protecting against NASH. In this paper, we review the important regulatory functions of SIRT6 in the occurrence and development of NASH.
Animals ; Liver ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Non-alcoholic Fatty Liver Disease/metabolism* ; Oxidative Stress ; Sirtuins/metabolism*

This study was aimed to determine the effect of acute cerebral ischemia on the protein expression level of silent mating type information regulator 2 homolog 3 (Sirt3) in the neurons and clarify the pathological role of Sirt3 in acute cerebral ischemia. The mice with middle cerebral artery occlusion (MCAO) and primary cultured rat hippocampal neurons with oxygen glucose deprivation (OGD) were used as acute cerebral ischemia models in vivo and in vitro, respectively. Sirt3 overexpression was induced in rat hippocampal neurons by lentivirus transfection. Western blot was utilized to measure the changes in Sirt3 protein expression level. CCK8 assay was used to detect cell viability. Immunofluorescent staining was used to detect mitochondrial function. Transmission electron microscope was used to detect mitochondrial autophagy. The results showed that, compared with the normoxia group, hippocampal neurons from OGD1 h/reoxygenation 2 h (R2 h) and OGD1 h/R12 h groups exhibited down-regulated Sirt3 protein expression levels. Compared with contralateral normal brain tissue, the ipsilateral penumbra region from MCAO1 h/reperfusion 24 h (R24 h) and MCAO1 h/R72 h groups exhibited down-regulated Sirt3 protein expression levels, while there was no significant difference between the Sirt3 protein levels on both sides of sham group. OGD1 h/R12 h treatment damaged mitochondrial function, activated mitochondrial autophagy and reduced cell viability in hippocampal neurons, whereas Sirt3 over-expression attenuated the above damage effects of OGD1 h/R12 h treatment. These results suggest that acute cerebral ischemia results in a decrease in Sirt3 protein level. Sirt3 overexpression can alleviate acute cerebral ischemia-induced neural injuries by improving the mitochondrial function. The current study sheds light on a novel strategy against neural injuries caused by acute cerebral ischemia.
Animals ; Brain Ischemia ; Down-Regulation ; Infarction, Middle Cerebral Artery ; Mice ; Mitochondria ; Neurons/metabolism* ; Rats ; Reperfusion Injury ; Sirtuin 3/metabolism* ; Sirtuins

Aging ; genetics ; metabolism ; Animals ; Diabetes Mellitus ; enzymology ; metabolism ; Humans ; Longevity ; genetics ; physiology ; Neoplasms ; enzymology ; metabolism ; Neurodegenerative Diseases ; enzymology ; metabolism ; Obesity ; enzymology ; metabolism ; Sirtuins ; genetics ; metabolism

OBJECTIVETo study the regulatory role of SirT7, one of class histone deacetylases, on the proliferation of mouse embryonal carcinoma cell line P19.

METHODSWe used an expression plasmid of SirT7 (151-402 amino acid residues) and its vector respectively to establish a stably expressed SirT7 and its control P19 cell lines. Recombinant DNA techniques, Western blot, cell growth curve, and flow cytometry were used in this paper.

RESULTSCompared with the control cells, the P19 cells had significantly lower growth rate in stably expressed SirT7. G1 to S cell cycle arrests were only seen in the SirT7 over-expressed cell line.

CONCLUSIONSirT7 play a dominant role in the grow inhibition of the P19 cells.

Animals ; Cell Cycle ; physiology ; Cell Line, Tumor ; Cell Proliferation ; Genetic Vectors ; Mice ; Plasmids ; genetics ; Sirtuins ; genetics ; metabolism ; Transfection

Cerebral ischemia-reperfusion injury(CIRI) is a complex cascade process and seriously hinders the recovery of patients with acute ischemic stroke, which has become an urgent public health issue to be addressed. Silent information regulators(SIRTs) are a family of nicotinamide adenine dinucleotide(NAD~+)-dependent deacetylases, capable of deacylating the histone and non-histone lysine groups. Accumulating evidence has demonstrated that SIRTs are able to regulate the pathological processes such as oxidative stress, inflammatory response, mitochondrial dysfunction, and programmed cell death of CIRI through post-translational deacetylation, and exert the neuroprotection function. In this study, we reviewed the papers about the role and regulatory mechanisms of SIRTs in the pathological process of CIRI published in the past decade. Further, we summarized the research advance in the prevention and treatment of CIRI with Chinese medicine targeting SIRTs and the related signaling pathways. This review will provide new targets and theoretical support for the clinical application of Chinese medicine in treating CIRI during the occurrence of ischemic stroke.
Humans ; Brain Ischemia/therapy* ; Ischemic Stroke/therapy* ; Medicine, Chinese Traditional ; Oxidative Stress ; Reperfusion Injury/therapy* ; Sirtuins/metabolism*