SIRT1 mRNA Research Articles

The reason for the amelioration of N-methyl-N-nitrosourea-induced retinitis pigmentosa in rats by hydrogen-rich saline.

To investigate the effects of hydrogen-rich saline (HRS) on microglia activation and Sirtuin type 1 (Sirt1) in rats with N-methyl-N-nitrosourea (MNU)-induced retinitis pigmentosa (RP). Rats were divided into norm (N) group, model (M) group and HRS (H) group. Rats in M and H groups were given saline and HRS respectively prior to and after administration of MNU. At one day (d1) and d3 afterwards, electroretinogram and histological examination were performed to confirm the effects of HRS on retinal function and structure of MNU-induced RP. Immunofluorescence staining of anti-ionized calcium-binding adapter molecule 1 (Iba1), a maker of microglia cells, was performed, with quantitative real-time polymerase chain reaction (qRT-PCR) for its mRNA quantification. Moreover, Sirt1 mRNA and protein expression in the retinas were detected by Western blot and qRT-PCR. HRS preserved the retinal function and mitigated the reduction of photoreceptor degeneration in MNU-treated retinas. The presence of microglia cells was somewhat more obvious in H group than that in M group at d1. HRS suppressed the further activation of microglia cells, with the number of microglia cells less than that of M group at d3. Results of qRT-PCR of Iba1 were consistent with those of immunofluorescence staining, with the mRNA expression of Iba1 in H group more intensive than that of M group at d1 (P<0.05), while less than that of M group at d3 (P<0.05). Furthermore, the Sirt1 mRNA and protein expression decreased after MNU administration, while HRS mitigated the MNU-induced downregulation of Sirt1. HRS can effectively keep microglia activation induced by MNU to an appropriate extent, while upregulate Sirt1 in MNU-induced RP.

Impact of fasting followed by short-term exposure to interleukin-6 on cytochrome P450 mRNA in mice

The gene expression of the cytochrome P450 (CYP) enzyme family is regulated by numerous factors. Fasting has been shown to induce increased hepatic CYP mRNA in both humans and animals. However, the coordinated regulation of CYP, CYP-regulating transcription factors, and transcriptional co-factors in the liver linking energy metabolism to detoxification has never been investigated. Interleukin-6 (IL-6) has been suggested to be released during fasting and has been shown to regulate CYP expression. The present study investigated the hepatic mRNA content of selected CYP, AhR, CAR, PXR and PPARα in mice fasted for 18h and subsequently exposed to IL-6. Furthermore, the impact of fasting on PGC-1α, HNF-4α, SIRT1 and SIRT3 mRNA was examined. Fasting induced a marked increase in Cyp2b10, Cyp2e1 and Cyp4a10 mRNA, while CYP1a1, Cyp1a2, Cyp2a4 and Cyp3a11 mRNA levels remained unchanged. In accordance, the mRNA levels of CAR and PPARα were also increased with fasting. The PGC-1α, SIRT1 and SIRT3 mRNA levels were also increased after fasting, while the HNF-4α mRNA levels remained unchanged. In mice subjected to IL-6 injection, the fasting-induced PXR, PPARα and PGC-1α mRNA responses were lower than after saline injection. In conclusion, fasting was demonstrated to be a strong inducer of hepatic CYP mRNA as well as selected transcription factors controlling the expression of the investigated CYP. Moreover, the mRNA levels of transcriptional co-factors acting as energy sensors and co-factors for CYP regulation was also increased in the liver, suggesting crosstalk at the molecular level between regulation of energy metabolism and detoxification.

SIRT6 histone deacetylase functions as a potential oncogene in human melanoma.

Melanoma is an aggressive skin cancer that can rapidly metastasize to become fatal, if not diagnosed early. Despite recent therapeutic advances, management of melanoma remains difficult. Therefore, novel molecular targets and strategies are required to manage this neoplasm. This study was undertaken to determine the role of the sirtuin SIRT6 in melanoma. Employing a panel of human melanoma cells and normal human melanocytes, we found significant SIRT6 mRNA and protein upregulation in melanoma cells. Further, using a tissue microarray coupled with quantitative Vectra analysis, we demonstrated significant SIRT6 overexpression in human melanoma tissues. Lentiviral short hairpin RNA-mediated knockdown of SIRT6 in A375 and Hs 294T human melanoma cells significantly decreased cell growth, viability, and colony formation, induced G1-phase arrest and increased senescence-associated beta-galactosidase staining. As autophagy is important in melanoma and is associated with SIRT6, we used a qPCR array to study SIRT6 knockdown in A375 cells. We found significant modulation in several genes and/or proteins (decreases in AKT1, ATG12, ATG3, ATG7, BAK1, BCL2L1, CLN3, CTSB, CTSS, DRAM2, HSP90AA1, IRGM, NPC1, SQSTM1, TNF, and BECN1; increases in GAA, ATG10). Our data suggests that increased SIRT6 expression may contribute to melanoma development and/or progression, potentially via senescence-and autophagy-related pathways.

The anti-adiposity effect of bitter melon seed oil is solely attributed to its fatty acid components

BackgroundObesity is the leading chronic disease affecting people of all ages. The objective of this study was to optimize composition of a bitter melon seed oil (BMSO) product to maximize its anti-adiposity effect.MethodsBleaching oil, saponifiables and non-saponifiables were prepared from BMSO, with α-eleostearic acid (α-ESA) content in BMSO maintained in bleaching oil and saponifiables. C57BL/6 J mice were allocated into five groups (n = 10/group) to receive diet C [30% soybean oil (SBO)], BM [25% SBO + 5% BMSO], BMS, BMNS or BMD. For the three latter diets, saponifiables (hydrolyzed fatty acids from BMSO), non-saponifiables (excluding fatty acids from BMSO) or bleaching oil (excluding pigments from BMSO), respectively, were added in amount equivalent to their content in 5% BMSO and SBO was added to bring total fat to 30%. After 14 wk., indices associated with adiposity and safety, as well as lipid metabolic signaling in white adipose tissue (WAT), were measured.ResultsThe body fat percentage of mice in group BM, BMS, BMNS, and BMD were 90 ± 26, 76 ± 21, 115 ± 30 and 95 ± 17% of that in group C. Based on body fat percentage and plasma leptin concentrations, an anti-adiposity effect was evident in groups BM, BMS and BMD (greatest effect in BMS). Histologically, inguinal fat had smaller adipocytes in groups BM, BMS and BMD (P < 0.05), but not in group BMNS, relative to group C. There were no differences among groups in blood pressure or heart rate. Moreover, Sirt1 mRNA levels in inguinal fat were significantly greater in groups BM, BMS and BMD than group C.ConclusionWe concluded that the anti-adiposity function of BMSO was solely attributed to the fatty acid fraction, with the free fatty acid form having the greatest effect.

SIRT1 is a positive regulator of in vivo bone mass and a therapeutic target for osteoporosis.

Overexpression or pharmacological activation of SIRT1 has been shown to extend the lifespan of mice and protect against aging-related diseases. Here we show that pharmacological activation of SIRT1 protects in two models of osteoporosis. Ovariectomized female mice and aged male mice, models for post-menopausal and aging-related osteoporosis, respectively, show significant improvements in bone mass upon treatment with SIRT1 agonist, SRT1720. Further, we find that calorie restriction (CR) results in a two-fold upregulation of sirt1 mRNA expression in bone tissue that is associated with increased bone mass in CR mice. Reciprocally, SIRT1 whole-body knockout (KO) mice, as well as osteoblast and osteoclast specific KOs, show a low bone mass phenotype; though double knockout mice (containing SIRT1 deleted in both osteoblasts and osteoclasts) do not show a more severe phenotype. Altogether, these findings provide strong evidence that SIRT1 is a positive regulator of bone mass and a promising target for the development of novel therapeutics for osteoporosis.

Sirt1 regulates apoptosis and extracellular matrix degradation in resveratrol-treated osteoarthritis chondrocytes via the Wnt/β-catenin signaling pathways.

Osteoarthritis (OA) has become a major public health problem with the increased aging population. Previous studies have demonstrated that resveratrol (RES) was able to increase the level of sirtuin 1 (Sirt1) in OA chondrocytes. However, further investigations are required to elucidate the precise molecular mechanism of RES and the potential link between Sirt1 and RES. Therefore, the present study used 30 clinical OA chondrocyte to examine chondrocyte viability, apoptosis rate and the mRNA and protein expression levels of Sirt1 and relevant genes implicated in apoptosis, extracellular matrix (ECM) degradation and Wnt/β-catenin signaling pathway. RES and nicotinamide were used as the stimulus and inhibitor, respectively. The results demonstrated that the apoptotic rate reduced as the cell population decreased from 13.83 to 6.55% in response to 10 µM RES. Expression levels of B-cell lymphoma 2 (Bcl-2) associated X protein (Bax), procaspase-3 and -9, matrix metalloproteinase 1 (MMP1), MMP3, MMP13, Wnt3a, Wnt5a, Wnt7a and β-catenin were significantly inhibited (P<0.01), whereas the level of Bcl-2 was significantly increased (P<0.01) in OA chondrocytes treated with 10 µM RES. These observations suggested that Sirt1 may regulate apoptosis and ECM degradation in RES-treated osteoarthritis chondrocytes via the Wnt/β-catenin signaling pathway.

The NAMPT/E2F2/SIRT1 axis promotes proliferation and inhibits p53-dependent apoptosis in human melanoma cells

Melanoma is the most common primary malignant neoplasm in adults, causing more deaths than any other skin cancer, necessitating the development of new target-based approaches. Current evidence suggests SIRT1, the mammalian nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase, and nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting NAD+ biosynthetic enzyme, together comprise a novel systemic regulatory network to play a pivotal role in cell proliferation and apoptosis. Nevertheless, how the regulation of this cofactor interfaces with signal transduction network remains poorly understood in melanoma. Here, we report NAMPT is highly expressed in melanomaassociated with poor overall survival in patients. Pharmacological and genetic inhibition of NAMPT decreased NAD+ levels and melanoma cell proliferation capacity, and NAMPT knockdown induced apoptosis through the activity of the tumor suppressor p53. Next, we demonstrate NAMPT regulates the transcription factor E2F family member 2 (E2F2) in the apoptosis process. Downstream, E2F2 control the mRNA and protein levels of SIRT1. Finally, we find NAMPT mediates the apoptosis resistance of melanoma cells through NAMPT-E2F2-SIRT1 axis, more than NAD+-driven transcriptional program. Accordingly, our results demonstrated that NAMPT is a prognostic marker in melanoma, and the identificationofNAMPT-E2F2-SIRT1 pathway establishes another link between NAMPT and apoptosis events in melanoma, with therapeutic implications for this deadly cancer.

Role of miR-124a in T cell activation and immunity in AIDS patients

The role of microRNA-124a (miR-124a) in the regulation of T cell activation and immunity in patients with AIDS, was studied to provide new insights for the study, diagnosis, alleviation and treatment of AIDS. RT-qPCR technique was used to quantitatively analyze the expression of miR-124a in peripheral blood CD4+ T cells. Dual-luciferase reporter assay system was established to report possible regulatory relations between miR-124a and its potential target gene SIRT1. RT-qPCR and western blot analysis were used to detect the expression level of mRNA and protein of the target genes in T cells. Normal CD4+ T cells from controls were transfected with miR-124a mimics and its negative control, and miR-124a inhibitor and its negative control were transfected into CD4+ T cells from patients with AIDS by T lymphocyte transfection kit to detect the relative expression level of SIRT1 mRNA and protein. The levels of interferon (IFN)-γ, interleukin (IL)-10, transforming growth factor (TGF)-β, IL-2, IL-4 and IL-6 secreted by T helper cells were detected by enzyme-linked immunosorbent assay (ELISA). miR-124a was upregulated in CD4+ T cells of patients with AIDS. The results of firefly luciferase activity detection showed that miR-124a can directly interact with target gene SIRT1 and negatively regulate its expression. miR-124a mimics/inhibitor transfection experiments showed that overexpression of miR-124a in normal CD4+ T cells significantly reduced SIRT1 expression compared with control group, and the expression of miR-124a was positively correlated with IL-10 and TGF-β expression and negatively correlated with IFN-γ expression, but showed no correlation with other cytokines. In AIDS patients, the inhibition of expression of miR-124a in CD4+ T cells significantly increased the expression of SIRT, at the same time, the expression levels of IL-10 and TGF-β were significantly decreased, while the expression level of IFN-γ was significantly increased and no significant difference was found in the expression of other cytokines. The expression of miR-124a in CD4+ T cells of AIDS patients was upregulated and the Th2 type CD4+ T cells are activated by SIRT1 expression inhibition, which in turn enhance the immunity of HIV-infected cells. Our study provides a new molecular target for the diagnosis, alleviation and treatment of AIDS.

MiR-181b regulates steatosis in nonalcoholic fatty liver disease via targeting SIRT1

Non-alcoholic fatty liver diseases (NAFLD) is one of the leading cause of chronic liver diseases in the world. However, the pathogenesis of NAFLD is still unclear. Emerging studies have demonstrated that microRNAs (miRs) are profoundly involved in NAFLD and related metabolic diseases. Here, we investigated the mechanisms by which miR-181b influences NAFLD via direct targeting SIRT1. The expression of miR181b was up-regulated while SIRT1 was down-regulated in both human NAFLD patients and high fat diet (HFD) induced NAFDL mice model. And palmitic acid (PA) treatment increased the miR-181b expression while decreased SIRT1 expression in HepG2 cells. Further, we identified that SIRT1 is a direct downstream target of miR-181b. Ectopic expression of miR-181b significantly repressed the 3′-UTR reporter activities of SIRT1 in a dose-dependent manner, while the effect of miR-181b was interrupted when the binding site of miR-181b within the SIRT1 3′-UTR was mutated. And overexpression of miR-181b reduced both the mRNA and protein levels of SIRT1 in HepG2 cells. We also found that inhibition of miR-181b expression alleviates hepatic steatosis both in vitro and in vivo. And the effect of miR-181b on steatosis was blocked by SIRT1 overexpression. Taken together, our data indicated that increased expression of miR-181b potentially contributes to altered lipid metabolism in NAFLD. Downregulation of miR-34a may be a therapeutic strategy against NAFLD by regulating its target SIRT1.

Association of sirtuins with clinicopathological parameters and overall survival in gastric cancer.

To evaluate the associations of sirtuins (SIRT1-7) with clinicopathological parameters in gastric cancer, sirtuins expression profile in NCBI GEO datasets, GSE62254 and GSE15459, was integrated and analyzed. The results suggested that SIRT4, SIRT6, and SIRT7 were associated with Lauren classification and SIRT3-5 were associated with pStage in gastric cancer. Then an online database derived from 1,065 gastric cancer cases, Kaplan-Meier plotter, was used to explore the associations of the mRNA levels of sirtuins with overall survival in gastric cancer. Survival curves generated from Kaplan-Meier plotter suggested that high expression of SIRT1 mRNA was favorable for overall survival in gastric cancer (SIRT1: HR = 0.64, 95% CI = 0.54–0.76, P = 2.2E-07), high expressions of SIRT2-4 and SIRT6-7 were poor for overall survival (SIRT2: HR = 2.31, 95% CI = 1.87–2.87, P = 3.6E-15; SIRT3: HR = 1.99, 95% CI = 1.62–2.45, P = 2.6E-11; SIRT4: HR = 1.41, 95% CI = 1.19–1.68, P = 6.6E-05; SIRT6: HR = 2.02, 95% CI = 1.66–2.47, P = 1.7E-12; SIRT7: HR = 1.96, 95% CI = 1.63–2.35, P = 2.7E-13), whereas no significant association existed between SIRT5 mRNA expression and overall survival. Further analyses stratified by gender, stages, Lauren classification, differentiation, treatment, and HER2 status were also performed. In summary, high SIRT1 mRNA level was associated with better overall survival, SIRT2-4 and 6–7 were associated with poor overall survival, whereas SIRT5 did not show significant association with overall survival in gastric cancer.

Targeting Sirt1 in a rat model of high-fat diet-induced non-alcoholic fatty liver disease: Comparison of Gegen Qinlian decoction and resveratrol.

The present study aimed to explore the mechanism of action of Gegen Qinlian decoction (GGQLD) in experimental non-alcoholic fatty liver disease (NAFLD). A total of 30 rats were randomly divided into five groups: The chow, model, high- and low-dose GGQLD (GGQLD-H and GGQLD-L, respectively) and resveratrol (Resl) groups, and were treated with saline, GGQLD and Resl when a model of high-fat diet (HFD)-induced NAFLD was established. Blood lipid and liver enzymes were detected following treatment for 8 weeks and liver tissue pathology was observed using Oil Red O and haematoxylin and eosin staining. Furthermore, the liver protein and mRNA expression of sirtuin (Sirt)1, peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) were measured using western blotting and reverse transcription-quantitative polymerase chain reaction. Compared with the chow group, the model group demonstrated significantly increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels (P<0.01). GGQLD doses and Resl attenuated the elevated serum ALT and AST levels. GGQLD-H and Resl significantly increased the serum high-density lipoprotein cholesterol level compared with that in the model group (P<0.01), while GGQLD-L and Resl significantly decreased serum low-density lipoprotein cholesterol levels (P<0.01). The GGQLDs and Resl groups revealed an evident improvement in Sirt1 protein and mRNA expression. Although GGQLD and Resl significantly decreased NF-κB gene expression compared with the model group (P<0.01), the effect on NF-κB protein expression was not significant. Furthermore, the PGC-1α gene and protein expression in the HFD rat group slightly decreased compared to the levels in the chow group, but the decrease was insignificant. However, an evident increase in PGC-1α mRNA expression was observed in the GGQLD-H group compared with the model group (P<0.01). Histological staining revealed that GGQLD and Resl decreased the lipid droplets in hepatocytes and normalized steatosis in rats fed with a HFD. The results indicated that GGQLD treatment may be a potent strategy for managing NAFLD by managing lipid metabolism and inflammatory and histological abnormalities by triggering the Sirt1 pathway.

A study of Sirt1 regulation and the effect of resveratrol on synoviocyte invasion and associated joint destruction in rheumatoid arthritis.

The aim of the current study was to investigate the role and mechanism of sirtuin 1 (Sirt1) in the regulation of synovial cell invasion and joint destruction in rheumatoid arthritis (RA). The Sirt1 protein and mRNA levels in fibroblast-like synoviocytes (FLS) isolated from RA synovial tissues were compared with normal tissues by western blot and reverse transcription-polymerase chain reaction. RA FLS were then treated with the Sirt1 agonist resveratrol (1, 3 and 10 µg/ml) for 48 h, and their invasiveness and expression of matrix metalloproteinase (MMP) 1 and MMP13 protein and mRNA were measured. Furthermore, a collagen-induced arthritis (CIA) rat model was established and the rats were divided into a model group, and low- and high-dose resveratrol (2.5 and 10 mg/kg/day) groups to receive an intraperitoneal injection of resveratrol for 42 consecutive days. The joint morphology, arthritis index (AI), and MMP1 and MMP13 expression in synovial tissues was monitored. The Sirt1 protein and mRNA levels in RA FLS were significantly lower compared with normal FLS (P<0.01). The resveratrol treatment significantly inhibited the invasive ability of RA FLS (P<0.01) and reduced MMP1 and MMP13 expression (P<0.01). The AI in low- and high-dose groups was significantly lower compared with the model group from day 28 (P<0.01). Resveratrol also reduced the swelling and damage and decreased MMP1 and MMP13 expression levels in CIA rats (P<0.01). The resveratrol-induced upregulation of Sirt1 in RA FLS may significantly inhibit the invasion of these cells and reduce the degree of joint damage, which may be mediated through the inhibition of MMP1 and MMP13 expression. The present results suggested a regulatory role for Sirt1 in RA pathogenesis, and demonstrated the beneficial effects of resveratrol, which may have potential as an alternative therapeutic strategy for the treatment of patients with RA.

P53 inhibits the upregulation of sirtuin 1 expression induced by c-Myc.

Sirtuin 1 (Sirt1), a conserved NAD+ dependent deacetylase, is a mediator of life span by calorie restriction. However, Sirt1 may paradoxically increase the risk of cancer. Accordingly, the expression level of Sirt1 is selectively elevated in numerous types of cancer cell; however, the mechanisms underlying the differential regulation remain largely unknown. The present study demonstrated that oncoprotein c-Myc was a direct regulator of Sirt1, which accounts for the upregulation of Sirt1 expression only in the cells without functional p53. In p53 deficient cells, the overexpression of c-Myc increased Sirt1 mRNA and protein expression levels as well as its promoter activity, whereas the inhibitor of c-Myc, 10058-F4, induced decreased Sirt1 basal mRNA and protein expression levels. Deletion/mutation mapping analyses revealed that c-Myc bound to the conserved E-box[-189 to -183 base pair (bp)] of the Sirt1 promoter. In addition, p53 and c-Myc shared at least response element and the presence of p53 may block the binding of c-Myc to the Sirt1 promoter, thus inhibit the c-Myc mediated upregulation of Sirt1 promoter activity. The present study indicated that the expression level of Sirt1 was tightly regulated by oncoprotein c-Myc and tumor suppressor p53, which aids an improved understanding of its expression regulation and tumor promoter role in certain conditions.

MiR-200a-3p promotes b-Amyloid-induced neuronal apoptosis through down-regulation of SIRT1 in Alzheimer's disease.

The aberrantly expressed microRNAs (miRNAs) including miR-200a-3p have been reported in the brains of Alzheimer's disease (AD) patients in recent researches. Nevertheless, the role of miR-200a-3p in AD has not been characterized. The purpose of this study was to examine whether miR-200a-3p regulated β-Ameyloid (A β)-induced neuronal apoptosis by targeting SIRT1, a known anti-apoptotic protein. An increased level of miR-200a-3p and a decreased level of SIRT1 in the hippocampus of APPswe/PS delta E9 mice (a model for AD) were observed. To construct an in vitro cell model of AD, PC12 cells were cultured in presence of A β 25-35. The results of flow cytometry analysis showed that the apoptosis rate and cleaved-caspase-3 expression in PC12 cells exposed to A β 25-35 were remarkably increased, but the apoptosis rate and cleaved-caspase-3 activity were decreased when cells were transfected with anti-miR-200a-3p. On the other hand, MTT assay showed that the cell survival rate was increased in the A β 25-35 + anti-miR-200a-3p group compared with the A β 25-35 + anti-miR-NC group. Dual-luciferase reporter gene assay validated the predicted miR-200a-3p binding sites in the 3'- UTR of SIRT1 mRNA. In addition, downregulation of SIRT1 promoted A β25-35-induced neuronal apoptosis and cleavedcaspase- 3 level in PC12 cells, whereas anti-miR-200a-3p reversed these effects. Knockdown of SIRT1 decreased the inhibitory effect of A β 25-35 on cell viability, while anti-miR-200a-3p attenuated this effect. Overall, the results suggest that suppression of miR-200a-3p attenuates A β 25-35-induced apoptosis in PC12 cells by targeting SIRT1. Thus, miR-200a-3p may be a potential therapeutic target for treatment of AD.

Nicotinamide mononucleotide requires SIRT3 to improve cardiac function and bioenergetics in a Friedreich's ataxia cardiomyopathy model.

Increasing NAD+ levels by supplementing with the precursor nicotinamide mononucleotide (NMN) improves cardiac function in multiple mouse models of disease. While NMN influences several aspects of mitochondrial metabolism, the molecular mechanisms by which increased NAD+ enhances cardiac function are poorly understood. A putative mechanism of NAD+ therapeutic action exists via activation of the mitochondrial NAD+-dependent protein deacetylase sirtuin 3 (SIRT3). We assessed the therapeutic efficacy of NMN and the role of SIRT3 in the Friedreich's ataxia cardiomyopathy mouse model (FXN-KO). At baseline, the FXN-KO heart has mitochondrial protein hyperacetylation, reduced Sirt3 mRNA expression, and evidence of increased NAD+ salvage. Remarkably, NMN administered to FXN-KO mice restores cardiac function to near-normal levels. To determine whether SIRT3 is required for NMN therapeutic efficacy, we generated SIRT3-KO and SIRT3-KO/FXN-KO (double KO [dKO]) models. The improvement in cardiac function upon NMN treatment in the FXN-KO is lost in the dKO model, demonstrating that the effects of NMN are dependent upon cardiac SIRT3. Coupled with cardio-protection, SIRT3 mediates NMN-induced improvements in both cardiac and extracardiac metabolic function and energy metabolism. Taken together, these results serve as important preclinical data for NMN supplementation or SIRT3 activator therapy in Friedreich's ataxia patients.

MiR-34a and miR-9 are overexpressed and SIRT genes are downregulated in peripheral blood mononuclear cells of aging humans.

Increased expression of sirtuins lowers the risk of age-related diseases, while their role in the regulation of longevity is not firmly established. Since aging is associated with immunosenescence, we tested whether sirtuin expression was modified in peripheral blood mononuclear cells (PBMC) in an age-related manner and whether this might result from altered expression of the selected miRNAs. The expression of seven SIRT genes and of SIRT1 mRNA-interacting miR-9, miR-34a, miR-132, and miR-199a-5p was evaluated by real-time PCR in PBMC originating from young (Y, n = 57, mean age 27 ± 4.3 years), elderly (E, n = 52, 65 ± 3.4 years), and long-lived (L, n = 56, 94 ± 3.5 years) individuals. Older age was associated with a decreased expression of the majority of the SIRT genes. Most severely affected were median expressions of SIRT1 ( P = 0.000001 for the whole studied group, Y vs. E: P < 0.000001, Y vs. L: P < 0.000001), and of SIRT3 ( P = 0.000001, Y vs. E: P = 0.000004, Y vs. L: P = 0.000028). Older age was also associated with the increased median expression of miR-34a ( P = 0.000001, Y vs. E: P = 0.001, Y vs. L: P = 0.000004) and of miR-9 ( P = 0.05, Y vs. L: P = 0.054). In functional studies, miR-9 interacted with the 3'UTR of SIRT1 mRNA. The SIRT1 mRNA level negatively correlated with the expression of miR-34a ( r = -0.234, P = 0.003). In conclusion, age-related decrease of SIRT1 expression in PBMC might in part result from overexpression of miR-34a and miR-9. In addition, the sustained expression of the SIRT genes in PBMC is not a prerequisite to longevity in humans but might be one of the reasons for the immune system dysfunction in the elderly. Impact statement High expression of sirtuins, particularly SIRT1, lowers the risk of age-related diseases and probably slows down the rate of aging; therefore, their sustained expression should be one of the features of longevity. However, in this work we show that in peripheral blood mononuclear cells (PBMC) of long-lived individuals, expression of majority of the SIRT genes is significantly lower than in cells of young study subjects. In long-lived individuals, downregulation of SIRT1 coexists with upregulation of SIRT1 mRNA-interacting miR-34a and miR-9, indicating the role of epigenetic drift in age-dependent deregulation of SIRT1 expression. Such constellation of SIRT1, miR-34a, and miR-9 expression in PBMC of successfully aging long-lived individuals indicates that, at least in these individuals, it is not a risk factor for morbidity and mortality. It might however affect the function of the immune system and, therefore, aging individuals can profit from interventions increasing the level of SIRT1.

SIRT1 signaling pathway mediated the protective effects on myocardium of rats after endurance training and acute exhaustive exercise

Objective: To detect the expression of SIRT1 and Ac-FOXO1 in rats after endurance training and acute exhaustive exercise, and explicit the myocardial protective effect of SIRT1. Methods: Rats were randomly divided into four groups: control group(n=20), exhaustive exercise group (E group, n=20), exhaustive exercise group + endurance training (TE group, n=18), exhaustive exercise group + endurance training + selective SIRT1 inhibitor (TSE group, n=17). The Control and E groups were fed routinely for 5 weeks. The TE and TSE groups were subjected to swimming exercise for 5 weeks for endurance exercising. The TSE group was intraperitoneally injected with selective SIRT1 inhibitor Sirtinol(2 mg/kg) at 30 minutes before endurance exercising. The E, TE and TSE groups were subjected to exhaustive exercise. The myocardial tissues of rats were collected after exhaustive exercise. Real-time polymerase chain reaction (PCR) and Western blot analysis were performed to detect the myocardial mRNA and protein expressions of SIRT1 and Ac-FOXO1. The myocardial protein expression of Bax and Bcl-2 was also detected by Western blot. Terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) assay was used to assess the apoptosis of myocardial cells. Results: Compared with Control group, the SIRT1 and Bcl-2 expression in the myocardial tissue was obviously decreased, while the Ac-FOXO1, Bax, and the myocardial cell apoptosis were significantly increased in E group (all P<0.01). Compared with E group, the expression of SIRT1 and Bcl-2 was obviously up-regulated (both P<0.01), while the Ac-FOXO, Bax and the myocardial cell apoptosis was significantly reduced in TE group (all P<0.01). Compared with TE group, the SIRT1 and Bcl-2 expression was obviously lower (both P<0.01), while Ac-FOXO1, Bax, and the cell apoptosis were significantly higher in group TSE (all P<0.01). Conclusion: Endurance training could protect myocardium by reducing the myocardial oxidative stress injury and apoptosis via activating SIRT1 signaling pathway, up-regulating the myocardial expression of SIRT1 and regulating the deacetylation of FOXO1.

Changes in sirtuin 2 and sirtuin 3 mRNA expressions in rheumatoid arthritis.

Sirtuins (SIRTs) play a prominent role in metabolism, apoptosis, aging, inflammation, and epigenetics. Inflammation, apoptosis, and epigenetics are pathogenic issues in rheumatoid arthritis (RA). This study aimed to evaluate SIRT2 and SIRT3 mRNA expressions in patients with RA. Fifty-four patients with RA and 26 healthy controls were enrolled. Disease activity was determined using the disease activity score (DAS) 28-erythrocyte sedimentation rate (ESR) (score of >2.6 was considered to be active). SIRT2 and SIRT3 mRNA expressions in the extracellular plasma were investigated by real-time PCR. SIRT3 mRNA expression was higher in the RA group than in the healthy control group (4.64 fold, p<0.001), whereas SIRT2 mRNA expression was relatively lower in the RA group than in the healthy control group (0.55 fold, p=0.109). However, SIRT2 (1.73 fold, p=0.065) and SIRT3 (3.58 fold, p=0.051) mRNA expressions were relatively higher in patients with active RA than in those with inactive RA. In RA, SIRT3 mRNA expression is increased, whereas SIRT2 mRNA expression is decreased. Conversely, SIRT2 and SIRT3 mRNA expressions increase in active RA. Therefore, the fate of each SIRT may differ in RA.

Comparison of Sirtuin 3 Levels in ALS and Huntington's Disease-Differential Effects in Human Tissue Samples vs. Transgenic Mouse Models.

Neurodegenerative diseases are characterized by distinct patterns of neuronal loss. In amyotrophic lateral sclerosis (ALS) upper and lower motoneurons degenerate whereas in Huntington’s disease (HD) medium spiny neurons in the striatum are preferentially affected. Despite these differences the pathophysiological mechanisms and risk factors are remarkably similar. In addition, non-neuronal features, such as weight loss implicate a dysregulation in energy metabolism. Mammalian sirtuins, especially the mitochondrial NAD+ dependent sirtuin 3 (SIRT3), regulate mitochondrial function and aging processes. SIRT3 expression depends on the activity of the metabolic master regulator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a modifier of ALS and HD in patients and model organisms. This prompted us to systematically probe Sirt3 mRNA and protein levels in mouse models of ALS and HD and to correlate these with patient tissue levels. We found a selective reduction of Sirt3 mRNA levels and function in the cervical spinal cord of end-stage ALS mice (superoxide dismutase 1, SOD1G93A). In sharp contrast, a tendency to increased Sirt3 mRNA levels was found in the striatum in HD mice (R6/2). Cultured primary neurons express the highest levels of Sirt3 mRNA. In primary cells from PGC-1α knock-out (KO) mice the Sirt3 mRNA levels were highest in astrocytes. In human post mortem tissue increased mRNA and protein levels of Sirt3 were found in the spinal cord in ALS, while Sirt3 levels were unchanged in the human HD striatum. Based on these findings we conclude that SIRT3 mediates the different effects of PGC-1α during the course of transgenic (tg) ALS and HD and in the human conditions only partial aspects Sirt3 dysregulation manifest.

A 7-day high protein hypocaloric diet promotes cellular metabolic adaptations and attenuates lean mass loss in healthy males

Summary Mitochondrial quantity and density are associated with increased oxidative metabolism. It has been demonstrated that a hypocaloric high fat/low carbohydrate (HF/LC) diet can up-regulate transcriptional markers of mitochondrial biogenesis; this was yet to be explored in vivo subsequent to a high protein/low carbohydrate (HP/LC) diet. Thus the aims of the study were to explore such diets on transcriptional markers or mitochondrial biogenesis, body composition and resting metabolic rate (RMR). Forty-five healthy male participants were randomly assigned one of four intervention diets: eucaloric high protein low carbohydrate (PRO-EM), hypocaloric high protein low carbohydrate (PRO-ER), eucaloric high carbohydrate (CHO-EM) or hypocaloric high carbohydrate (CHO-ER). The macronutrient ratio of the high protein diet and high carbohydrate diets was 40:30:30% and 10:60:30% (PRO:CHO:FAT) respectively. Energy intake for the hypocaloric diets were calculated to match resting metabolic rate. Participants visited the laboratory on 3 occasions each separated by 7 days. On each visit body composition, resting metabolic rate and a muscle biopsy from the vastus lateralis was collected. Prior to visit 1 and 2 habitual diet was consumed which was used as a control, between visit 2 and 3 the intervention diet was consumed continuously for 7-days. No group × time effect was observed, however in the PRO-ER group a significant increase in AMPK, PGC-1α, SIRT1 and SIRT3 mRNA expression was observed post diet intervention groups (p