Sirtuin 1 Protein Expression Levels Research Articles

Sirtuin 1 is a potential therapeutic candidate gene for fetal growth restriction via insulin-like 4

Objective Insufficient placental development causes various obstetric complications, including fetal growth restriction (FGR). The Sirtuin 1 (SIRT1) and insulin-like 4 (INSL4) protein-coding genes have been demonstrated to play an important role in placental development. However, no treatment for FGR is available due to placental dysfunction. Therefore, this study aimed to examine the potential of the SIRT1–INSL4 axis as a treatment candidate for FGR caused by insufficient placental development. Methods Twenty patients were enrolled, including 10 with FGR and 10 full-term controls. FGR and control placental samples were collected. Quantitative real-time polymerase chain reaction, immunohistochemical analysis, and western blotting were used to analyze INSL4 and SIRT1 expression. An in-vitro loss-of-function approach with the human choriocarcinoma cell line BeWo was applied for functional analyses of SIRT1 in placental development. BeWo cells were differentiated into syncytiotrophoblasts by silencing SIRT1 using small interfering RNA. SIRT1 activator was added during differentiation of SIRT1-knockdown BeWo cells into syncytiotrophoblasts. Results The FGR samples had lower INSL4 and SIRT1 mRNA and protein expression levels than the control samples. Immunohistochemistry showed that both SIRT1 and INSL4 were expressed mainly in syncytiotrophoblasts. In-vitro analyses showed that SIRT1 knockdown decreased INSL4 expression; however, SIRT1 activator restored SIRT1 expression in SIRT1-silenced BeWo cells. Conclusions SIRT1 and INSL4 are downregulated in the placenta of FGR, and INSL4 is regulated by SIRT1. These findings indicate that the SIRT1–INSL4 axis may be a potential therapeutic target for FGR.

Hsa_circ_0093884 bound to RNA-binding protein RPS3 ameliorates hepatocyte inflammation in anti-tuberculosis drug-induced liver injury by competitively activating SIRT1

Anti-tuberculosis drug-induced liver injury (ADLI) is one of the main factors hindering the efficacy of routine chemotherapy against tuberculosis. Understanding the mechanism of ADLI will aid in the effective treatment of patients with tuberculosis. Recently, we found that the expression of hsa_circ_0093884, a circular RNA derived from the NAD-dependent deacetylase, sirtuin-1 (SIRT1), was down-regulated in ADLI. Hsa_circ_0093884 was negatively correlated with the NLR family pyrin domain containing 3 (NLRP3) inflammasome and its overexpression increased the expression levels of NLRP3, interleukin-1β, and caspase-1. Mechanistically, RNA immunoprecipitation and immunofluorescence assays revealed that the ribosomal protein S3 (RPS3) could bind to hsa_circ_0093884 and SIRT1. Additionally, the expression of hsa_circ_0093884 was positively correlated with that of SIRT1, and the upregulation of hsa_circ_0093884 expression was crucial for the upregulation of SIRT1 expression. We confirmed that the mRNA and protein expression levels of SIRT1 were influenced by hsa_circ_0093884 and RPS3. Furthermore, hsa_circ_0093884 recruited RPS3 to increase SIRT1 mRNA and protein levels. Importantly, we found a marked decrease in the upregulating effect of hsa_circ_0093884 on SIRT1 owing to RPS3 depletion. To the best of our knowledge, this study is the first to reveal that hsa_circ_0093884 regulates SIRT1 expression and inhibits the inflammatory response by binding to RPS3 in ADLI, which may be used to develop novel strategies for ADLI treatment.

Sirtuin 1 participates in intervertebral disc degeneration via the nicotinamide phosphoribosyl transferase/nicotinamide adenine dinucleotide/sirtuin 1 pathway responsible for regulating autophagy of nucleus pulposus cells.

Disc degeneration is the main cause of discogenic low back pain, disc herniation, degenerative stenosis of spinal canal, lumbar spondylolisthesis and other diseases. In the process of intervertebral disc degeneration, water and extracellular matrix of nucleus pulposus tissues are lost, so the normal tension in the intervertebral disc cannot be maintained, which worsens the living environment of nucleus pulposus cells. Low back pain (LBP), with a high incidence rate of disability, has become an increasing health concern and a social and economic problem. The present study aimed to analyze the action mechanisms of nicotinamide phosphoribosyl transferase (Nampt) and sirtuin 1 (SIRT1) in intervertebral disc degeneration (IVDD). In total 26 patients with lumbar disc herniation who had surgical resection at The Third Affiliated Hospital of Jinzhou Medical University were recruited as the experimental group and their degenerative nucleus pulposus (DNP) tissues of intervertebral disc were collected. In addition, nucleus pulposus tissues of intervertebral disc were collected from 20 patients with burst fracture of lumbar spine at the same hospital (control). Nucleus pulposus cells from primary culturing were separated for subsequent experimentation. LC3 II/I, beclin-1, SIRT1 and NAMPT mRNA and protein expression levels were determined using reverse transcription-quantitative PCR and western blotting, respectively. Nicotinamide adenine dinucleotide (NAD) contents in nucleus pulposus cells was determined by NAD assay kit. The mRNA and protein expression levels of SIRT1 in DNP tissues were reduced compared with the control tissues and decreased with increasing disease severity. The expression of autophagy-associated LC3 II/I and beclin-1 in DNP tissues was reduced compared with control tissues. SIRT1 regulated the LC3 II/I and beclin-1 expression levels in nucleus pulposus cells. Treatment with resveratrol and inhibitor of SIRT1 showed that Nampt/NAD+/SIRT1 pathway participated in the process of IVDD by regulating autophagy of nucleus pulposus cells. SIRT1 serves a role in the process of IVDD through Nampt/NAD+/SIRT1 pathway that regulates autophagy of nucleus pulposus cells. SIRT1 may become a biological target for the treatment of IVDD.

Icariin improves testicular dysfunction via enhancing proliferation and inhibiting mitochondria-dependent apoptosis pathway in high-fat diet and streptozotocin-induced diabetic rats

BackgroundDiabetes mellitus (DM), a chronic metabolic disease, severely impairs male reproductive function. However, the underpinning mechanisms are still incompletely defined, and there are no effective strategies or medicines for these reproductive lesions. Icariin (ICA), the main active component extracted from Herba epimedii, is a flavonoid traditionally used to treat testicular dysfunction. Whether ICA can improve male reproductive dysfunction caused by DM and its underlying mechanisms are still unclear. In this study, by employing metformin as a comparative group, we evaluated the protective effects of ICA on male reproductive damages caused by DM and explored the possible mechanisms.MethodsRats were fed with a high fat diet (HFD) and then intraperitoneally injected with streptozotocin (STZ) to induce diabetes. Diabetic rats were randomly divided into T2DM + saline group, T2DM + metformin group and T2DM + ICA group. Rats without the treatment of HFD and STZ were used as control group. The morphology of testicular tissues was examined by histological staining. The mRNA expression levels were determined by quantitative real-time PCR. Immunostaining detected the protein levels of proliferating cell nuclear antigen (PCNA), hypoxia-inducible factor 1-alpha (HIF-1α) and sirtuin 1 (SIRT1) in testicular tissues. TUNEL assay was performed to determine cell apoptosis in the testicular tissues. The protein expression levels of HIF-1α and SIRT1 in the testicular tissues were determined by western blot assay.ResultsICA effectively improved male reproductive dysfunction of diabetic rats. ICA administration significantly decreased fasting blood glucose (FBG) and insulin resistance index (IRI). In addition, ICA increased testis weight, epididymis weight, sperm number, sperm motility and the cross-sectional area of seminiferous tubule. ICA recovered the number of spermatogonia, primary spermatocytes and Sertoli cells. Furthermore, ICA upregulated the expression of PCNA, activated SRIT1-HIF-1α signaling pathway, and inhibited intrinsic mitochondria dependent apoptosis pathway by upregulating the expression of Bcl-2 and downregulating the expression of Bax and caspase 3.ConclusionThese results suggest that ICA could attenuate male reproductive dysfunction of diabetic rats possibly via increasing cell proliferation and decreasing cell apoptosis of testis. ICA potentially represents a novel therapeutic strategy against DM-induced testicular damages.

MiR-135a-5p inhibitor protects glial cells against apoptosis via targeting SIRT1 in epilepsy.

Epilepsy is a common neurological disease that can induce severe physiological brain damage, including nerve cell apoptosis. MicroRNAs (miRs) have been widely investigated in epilepsy therapy. miR-135a-5p expression levels in children with temporal lobe epilepsy were found to be significantly increased. However, whether miR-135a-5p participates in epilepsy-induced cell apoptosis is not completely understood. In the present study, an in vitro model of epilepsy in BV2 microglia cells was induced using 6-µm kainic acid (KA). Reverse-transcription quantitative PCR was performed to analyze miR-135a-5p and sirtuin 1 (SIRT1) mRNA expression levels. Western blotting was performed to measure SIRT1 protein expression levels. BV2 cell proliferation and apoptosis were assessed by performing MTT assays and flow cytometry, respectively. A BCA protein assay kit was used to detect caspase-3 and caspase-9 activities. TargetScan and dual luciferase reporter assays were performed to investigate the interaction between miR-135a-5p and the 3'-untranslated region (UTR) of SIRT1. miR-135a-5p expression was significantly increased in the KA-induced in vitro model of epilepsy in BV2 microglia. miR-135a-5p inhibitor effectively promoted BV2 microglia proliferation and inhibited microglia apoptosis, whereas small interfering RNA targeting SIRT1 significantly repressed BV2 microglia proliferation and induced microglia apoptosis. In addition, the results demonstrated that the 3'-UTR of SIRT1 mRNA was targeted by miR-135a-5p, and SIRT1 knockdown attenuated miR-135a-5p inhibitor-mediated effects on epilepsy. In summary, the results of the present study identified the role of miR-135a-5p inhibitor pretreatment in protecting nerve cells against epilepsy-induced apoptosis and provided a novel strategy for the treatment of neural damage in seizures.

MiR-124-3p combined with miR-506-3p delay hepatic carcinogenesis via modulating sirtuin 1

Objective Our study aimed at exploring whether miR-124-3p and miR-506-3p collaboratively modulated sirtuin 1 (SIRT1) protein expression in liver cancer. Materials and methods: In this study, cell viability, migration and invasion were assessed using CCK8 and transwell assays, respectively. Immunohistochemical (IHC) staining and immunoblotting analysis were performed to evaluate SIRT1 protein expression levels in tissue specimens and cell lines. Moreover, the nude-mouse transplanted tumour model was used to assess liver cancer cell growth in vivo. Results: Our results showed that SIRT1 protein levels were significantly up-regulated in liver cancer tissues and cancerous cell lines. Conversely, miR-124-3p and miR-506-3p were down-regulated in liver cancer tissues and cell lines. The protein expression of SIRT1 was significantly declined in HepG2 and SMMC7721 cells after transfection with miR-124-3p or miR-506-3p mimics. miR-124-3p and miR-506-3p collaboratively caused a marked inhibition of liver cancer cell growth, migration and invasion, while the phenomena were neutralized by overexpression of SIRT1. In vivo experimental measurements also revealed that miR-124-3p and miR-506-3p synergistically inhibited SIRT1 protein expression and tumour growth in the nude-mouse transplanted tumour model. Conclusion: It was observed that miR-124-3p and miR-506-3p could cooperatively retard liver cancer cell growth via co-inhibiting SIRT1 protein expression.

Phosphocreatine Promotes Osteoblastic Activities in H2O2-Induced MC3T3-E1 Cells by Regulating SIRT1/FOXO1/PGC-1α Signaling Pathway.

Osteoporosis, characterized by bone loss, usually occurs with the increased bone resorption and decreased bone formation. H2O2-induced MC3T3-E1 cells are commonly used for the study of osteoblastic activities, which play a crucial role in bone formation. This study aimed to investigate the effects of Phosphocreatine (PCr) on the osteoblastic activities in H2O2-induced MC3T3-E1 cells and elaborate on the possible molecular mechanism. The Osteoprotegerin (OPG)/Receptor Activator of NF-κB Ligand (RANKL) ratio and osteogenic markers were detected to investigate the effects of PCr on osteoblastic activities, and the osteoblastic apoptosis was detected using Hochest staining. Moreover, oxidative stress, Adenosine Triphosphate (ATP) generation and the expression of Sirtuin 1 (SIRT1), Forkhead Box O 1 (FOXO1) and Peroxisome Proliferator-Activated Receptor Γ Coactivator-1α (PGC-1α) were also examined to uncover the possible molecular mechanism in H2O2-induced MC3T3-E1 cells. The results showed that PCr promoted the osteoblastic differentiation by increasing the expression levels of osteogenic markers of Alkaline Phosphatase (ALP) and Runt-related transcription factor 2 (Runx2), as well as increased the OPG/RANKL ratio and suppressed the osteoblastic apoptosis in H2O2-induced MC3T3-E1 cells. Moreover, treatment with PCr suppressed reactive oxygen species (ROS) over-generation and promoted the ATP production as well as increased the PGC-1α, FOXO1 and SIRT1 protein expression levels in H2O2-induced MC3T3-E1 cells. PCr treatment could promote osteoblastic activities via suppressing oxidative stress and increasing the ATP generation in H2O2-induced MC3T3-E1 cells. In addition, the positive effects of PCr on osteoblasts might be regulated by SIRT1/FOXO1/ PGC-1α signaling pathway.

In vitro inhibition effects of hepatitis B virus by dandelion and taraxasterol

Hepatitis B virus (HBV) causes hepatitis, which progresses to fatal liver diseases and remains a global health problem. Current treatments for chronic hepatitis B are unable to cure hepatitis. Thus, new antiviral drugs must be developed. In this study, the viral inhibition effects of dandelion and taraxasterol were assessed in HepG2.2.15 cell line. Taraxacum officinale F.H.Wigg. (compositae) with English name dandelion is used as a traditional herb for liver disorders and as a common antiviral agent. Taraxasterol is one of the active compounds of dandelion. The secretion of HBV DNA and HBV surface antigen (HBsAg) and HBeAg was detected using fluorescence quantitative PCR (qPCR) and ELISA, respectively. Intracellular HBsAg was detected by immunofluorescence. In order to demonstrate the potential mechanism of anti-viral activity, the expression levels of host factors polypyrimidine tract binding protein 1 (PTBP1) and sirtuin 1 (SIRT1) were detected with Western blotting and qPCR. Dandelion and taraxasterol effectively reduced the secretion of HBsAg, HBeAg and the HBV DNA in cell supernatants, and significantly reduced the intracellular HBsAg as indicated by immunofluorescence results. Taraxasterol may be one of the main effective components of dandelion. It significantly decreased the protein expression levels of PTBP1 and SIRT1. The present study revealed that dandelion and its component taraxasterol could inhibit HBV and may be a potential anti-HBV drug, whose potential targets were the host factors PTBP1 and SIRT1.

MiR-204 inhibits inflammation and cell apoptosis in retinopathy rats with diabetic retinopathy by regulating Bcl-2 and SIRT1 expressions.

To explore the influences of micro ribonucleic acid (miR)-204 on the rats with diabetic retinopathy by regulating the expressions of B-cell lymphoma 2 (Bcl-2) and sirtuin 1 (SIRT1). A total of 36 Sprague-Dawley rats were randomly assigned into normal group (n=12), model group (n=12), and miR-204 mimics group (n=12). No treatment was performed in the normal group, the diabetic retinopathy model was established in model group, and miR-204 mimics were administered for intervention after modeling in the inhibitor group. After 7 d, materials were sampled for detection. The expressions of Bcl-2 and SIRT1 were detected via immunohistochemistry, and their relative protein expression levels were determined via Western blotting (WB). Quantitative Polymerase Chain Reaction (qPCR) was performed to detect the expression of miR-204, and the content of inflammatory factors interleukin (IL)-6, IL-18, and tumor necrosis factor-α (TNF-α) was measured using enzyme-linked immunosorbent assay (ELISA). Finally, cell apoptosis was evaluated via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Immunohistochemistry results showed that the positive expression levels of Bcl-2 and SIRT1 were substantially lower in the model and miR-204 mimics groups than those in the normal group (p<0.05), and their positive expression levels in miR-204 mimics group were notably higher than those in model group (p<0.05). According to Western blot (WB) results, the relative protein expression levels of Bcl-2 and SIRT1 markedly declined in the other two groups compared with those in the normal group (p<0.05), while miR-204 mimics group exhibited remarkably higher relative protein expression levels of Bcl-2 and SIRT1 than the model group (p<0.05). The results of qPCR revealed that the relative expression level of miR-204 was markedly lowered in model and miR-204 mimics groups compared with that in the normal group (p<0.05), and its relative expression level in miR-204 mimics group was remarkably higher than that in the model group. It was found through enzyme-linked immunosorbent assay (ELISA) that compared with normal group, the other two groups had substantially increased content of IL-6, IL-18, and TNF-α (p<0.05), and the content of IL-6, IL-18, and TNF-α in miR-204 mimics group was markedly lower than that in the model group (p<0.05). According to TUNEL results, the apoptosis rate of cells rose substantially in the other two groups compared with that in the normal group (p<0.05), while was notably lower in the miR-204 mimics group than that in the model group (p<0.05). MiR-204 up-regulates Bcl-2 and SIRT1 expressions to inhibit the inflammation and cell apoptosis in rats with diabetic retinopathy.

Electroacupuncture reduces obesity by improving metabolism and up-regulating expression of hypothalamic Sirtuin 1 and proopiomelanocortin in obese rats

To observe the effect of electroacupuncture (EA) on expression of hypothalamic sirtuin 1(SIRT1) and proopiomelanocortin (POMC), and body weight, food-intake, blood glucose, and blood lipid levels in obese rats, so as to explore its mechanisms underlying improvement of obesity. Forty male Wistar rats were randomly divided into normal, model, EA, and sham EA groups (n＝10 rats in each group). The obesity model was established by feeding the rats with high fat diet. EA (2 Hz, 1 mA) was applied to "Zusanli" (ST36), "Zhongwan" (CV12), "Guanyuan" (CV4) and "Fenglong" (ST40) or sham acupoints (about 5 mm beside each acupoint, shallow needling) for 20 min, once every other day for 8 weeks. The rats' body weight and food-intake were recorded. The blood glucose (fasting plasma glucose: FPG, postprandial plasma glucose: PPG) and blood lipids (triglyceride: TG, total cholesterol: TC, non esterified fatty acid: NEFA) were assayed by using an automatic biochemical analyzer. The protein and mRNA expression levels of SIRT1 and POMC in the hypothalamus were detected by Western blot and quantitative real-time PCR, respectively. In comparison with the normal group, the body weight, food-intake, blood lipids, and PPG levels were significantly increased (P<0.05，P<0.01), and the expression levels of SIRT1 protein and mRNA in the hypothalamus were significantly doun-regulated in the model group (P<0.05). Following EA, the body weight, food-intake, blood lipids, and PPG levels were considerably down-regulated (P<0.01，P<0.05), and the expression levels of SIRT1 and POMC protein and mRNA in the hypothalamus were significantly up-regulated in the EA group rather than those in the sham EA and the model groups (P<0.05)．. EA can reduce the obese rats' body weight, food-intake, blood lipids and blood glucose, which may be associated with its effect in up-regulating the SIRT1 and POMC expression of hypothalamus.

SIRT1 inhibits apoptosis in invivo and invitro models of spinal cord injury via microRNA-494.

The aim of the present study was to investigate the function and mechanism of sirtuin 1 (SIRT1) in spinal cord injury (SCI). Reverse transcription-quantitative polymerase chain reaction was used to measure the expression levels of microRNA (miR)-494. MTT assay, lactate dehydrogenase activity assay and flow cytometry were used to analyze the effects of miR-494 on cell growth and apoptosis in a model of SCI. The present study demonstrated that SIRT1 expression was reduced; whereas miR-494 expression was increased in a rat model of SCI. Overexpression of miR-494 suppressed the protein expression levels of SIRT1, and induced p53 protein expression. Conversely, knockdown of miR-494 induced SIRT1 protein expression in an in vitro model of SCI. Furthermore, overexpression of miR-494 promoted cell apoptosis and decreased cell growth in an in vitro model of SCI; however, miR-494 knockdown enhanced cell growth and inhibited cell apoptosis. Administration of a SIRT1 agonist reduced the effects of miR-494 overexpression on cell apoptosis in an SCI model, whereas treatment with a p53 agonist reduced the effects of miR-494 knockdown on cell apoptosis in an SCI model. Together, these findings suggested that SIRT1 may inhibit apoptosis of SCI in vivo and in vitro through the p53 signaling pathway, whereas miR-494 suppressed SIRT1 and induced apoptosis.

Down-Regulation of SIRT1 Expression by mir-23b Contributes to Lipid Accumulation in HepG2 Cells.

Non-alcoholic fatty liver disease is one of the main causes of chronic liver disease and therefore is currently considered a major public health problem. Sirtuin 1 (SIRT1) is an NAD-dependent deacetylase enzyme that contributes in the regulation of metabolic processes and protects against lipid accumulation in hepatocytes. Its expression is potentially regulated by microRNAs which attach to the 3' untranslated region (3'-UTR) of their target mRNA. HepG2 cells were incubated by glucose to induce lipid accumulation and were subsequently transfected with mir-23b mimic and inhibitor. Real-time PCR was used for measuring the expression of mir-23b and SIRT1 mRNA. Cell survival assay and intracellular triglyceride measurement were performed using colorimetric methods. Determination of SIRT1 protein level and activity were done by western blot and fluorometric analysis, respectively. The interaction of miR-23b with 3'-UTR of SIRT1 mRNA was confirmed by dual luciferase. miR-23b mimic inhibited gene and protein expression of SIRT1, while the inhibitor of miR-23b significantly elevated the expression levels of SIRT1 mRNA and protein. The results showed that the 3'-UTR of SIRT1 mRNA is a direct target for miR-23b. The intracellular triglyceride level was increased following the inhibition of SIRT1 in transfected HepG2 cell by miR-23b mimic. Cell viability was decreased in response to miR-23b upregulation compared to control cells. miR-23b reduces the expression and activity of SIRT1 and therefore may be a causative factor in the enhancement of lipid accumulation in HepG2 cells.

Duodenal-Jejunal Bypass Surgery Stimulates the Expressions of Hepatic Sirtuin1 and 3 and Hypothalamic Sirtuin1.

BackgroundSirtuins mediate metabolic responses to nutrient availability and slow aging and accompanying decline in health. This study was designed to assess the expressions of sirtuin1 (SIRT1) and sirtuin3 (SIRT3) in the liver and hypothalamus after duodenal-jejunal bypass (DJB) surgery in rats.MethodsA total of 38 rats were randomly assigned to either sham group (n=8) or DJB group (n=30). DJB group was again divided into three groups according to the elapsed time after surgery (10 weeks, DJB10; 16 week, DJB16; 28 week, DJB28). The mRNA and protein expressions of SIRT1 and SIRT3 in the liver and hypothalamus were measured by reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry analyses. NAD+/NADH ratio was also measured.ResultsWe found increased mRNA and protein expression levels of SIRT1 in the liver of DJB16 and DJB28 groups compared with those of sham group. The mRNA and protein expressions of SIRT3 in the liver of DJB group increased proportionally to the elapsed time after DJB surgery. The mRNA expression levels of SIRT1 in the hypothalamus increased in DJB16 and DJB28 groups and protein expression levels of SIRT1 in the hypothalamus increased in DJB10, DBJ16, and DJB28 groups compared with sham group. We observed that mRNA and protein levels of SIRT3 in the hypothalamus of DJB group were not changed.ConclusionThis study proves that DJB increases SIRT1 and SIRT3 expressions in the liver and SIRT1 expression in the hypothalamus. These results suggest the possibility of sirtuins being involved in bypass surgery-induced metabolic changes.

Hypermethylation of the HIC1 promoter and aberrant expression of HIC1/SIRT1 contribute to the development of thyroid papillary carcinoma.

Hypermethylation leading to the loss of hypermethylated in cancer-1 (HIC1) gene expression occurs in many different types of human cancer. HIC1 is a transcriptional repressor that directly binds to the promoter region of NAD-dependent deacetylase sirtuin-1 (SIRT1). SIRT1 functions in cell growth, is anti-apoptotic, protect neurons, functions in senescence, and regulates energy restriction. Epigenetic modification and dysregulation affecting the HIC1/SIRT1 axis is potentially important for the development of malignancies. However, the importance of HIC1 expression in the development of papillary thyroid carcinoma, especially in Chinese patients, is uncertain. Therefore, we assessed the level of methylation in the HIC1 promoter and the mRNA and protein expression levels of HIC1 and SIRT1 in human thyroid papillary carcinoma and tumor adjacent control tissues. The demethylation reagent 5-aza-2′-deoxyctidine (5-aza-dc) and an HIC1 overexpression plasmid were used to manipulate the HIC1/SIRT1 pathway, and the effects on cell senescence, apoptosis, and cell cycle progression were assessed. Compared to normal thyroid tissue, thyroid tumors had lower expression of HIC1 and higher SIRT1 expression. The level of HIC1 methylation was also higher in thyroid carcinoma tissues than adjacent tissues. HIC1 expression was closely correlated with patient age and tumor progression. Restoration of HIC1 expression through an overexpression plasmid or 5-aza-dC treatment reduced SIRT1 expression and cell proliferation, and led to senescence, cell cycle arrest, and apoptosis. Aberrant expression of HIC1/SIRT1 and hypermethylation of the HIC1 promoter may be critical for the development and progression of papillary thyroid cancer.

Qing'E formula alleviates the aging process in D-galactose-induced aging mice.

Qing'E formula (QEF) is a clinically used prescription with four ingredients, Eucommiae Cortex, Psoraleae Fructus, Juglandis Semen and Garlic Rhizoma, from the Song dynasty (10th century CE). The present study aimed to investigate the anti-aging effect and mechanisms of QEF on D-galactose-induced aging mice. A mouse subacute aging model was established by subcutaneous injection of D-galactose at the neck consecutively for 8 weeks. Motor activity and memory impairment of the mice were evaluated by the rotarod test and passive avoidance test, respectively. Serum and liver parameters were analyzed with biochemical kits. Hippocampal mRNA and protein expression levels were examined by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. QEF administration significantly ameliorated the impaired motor and memory of aging mice. In the serum, QEF reduced blood urea nitrogen, creatinine, nitric oxide (NO) and malondialdehyde (MDA) levels, and inhibited alanine aminotransferase and aspartate aminotransferase activities. In the liver, QEF increased the glutathione level, enhanced total antioxidant capacity and catalase activity, deceased NO and MDA production, and reduced NO synthase activity. In the hippocampus, QEF elevated gene expression levels of Klotho, sirtuin 1 (SIRT1), forkhead box transcription factor O3, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), insulin-like growth factor-1 and peroxiredoxin-3. QEF increased protein expression levels of Klotho and SIRT1, and decreased that of PGC-1α in the hippocampus. In conclusion, QEF attenuated the aging process in D-galactose-treated mice, which may be mediated through enhancing the antioxidants in the body, protecting renal and hepatic health, and balancing hippocampal expression levels of the longevity-related genes.

Resveratrol attenuates inflammatory hyperalgesia by inhibiting glial activation in mice spinal cords.

The present study aimed to investigate the effect of resveratrol on inflammatory pain. Mice were injected intraperitoneally with lipopolysaccharide (LPS) for 5consecutive days to induce subacute systemic inflammation. Acetic acid‑induced writhing tests and tail‑flick tests were performed following the final LPS injection. Glial fibrillary acidic protein (GFAP; an astrocyte‑specific activation marker), ionized calcium binding adapter molecule1 (Iba‑1; a microglia‑specific activation marker) and sirtuin1 (SIRT1) protein expression levels were detected using immunohistochemistry analysis or western blotting. Following administration of LPS for 5days, the number of writhes increased and the tail‑flick latency decreased. Resveratrol (10 or 20mg/kg) partly inhibited LPS‑induced hyperalgesia and prevented the increase in tumor necrosis factor‑α and interleukin6 levels induced by LPS. LPS injection reduced the SIRT1 protein expression and increased the number of GFAP‑positive and Iba‑1‑positive cells in the spinal cord. Resveratrol increased the SIRT1 protein expression levels and decreased the number of GFAP‑positive and Iba‑1‑positive cells in LPS‑treated mice. The protective effect of resveratrol was partly blocked by a selective SIRT1 inhibitor, EX‑257. Results from the present study suggest that subacute treatment with LPS induced the activation of glial cells and hyperalgesia. Resveratrol was demonstrated to inhibit the activation of glial cells and attenuate inflammatory hyperalgesia in a SIRT1‑dependent manner.

Sirtuin 1 regulates lipid metabolism associated with optic nerve regeneration.

Injury to the optic nerve may lead to axonal degeneration, followed by the gradual death of retinal ganglion cells (RGCs), which results in irreversible vision loss. In the present study the mechanism of optic nerve injury, and the following regeneration and repair processes associated with sirtuin 1 (SIRT1)‑regulated lipid metabolism were analyzed. In addition, the treatment of optic nerve injury using resveratrol was investigated. A rat model of optic nerve damage was prepared, and rats were divided into control, model and resveratrol groups. The model rats (with optic nerve damage) were treated with phosphate‑buffered saline or resveratrol once a day for seven, 14 and 21 days. The rats were then sacrificed and the optic nerve was dissected. The expression levels of SIRT1, sterol regulatory element‑binding protein 2 (SREBP‑2) and 3‑hydroxy‑3‑methylglutaryl‑CoA reductase (HMGCR) mRNA in the optic nerve were measured by reverse transcription‑quantitative polymerase chain reaction, and the protein expression of SIRT1, SREBP2 and HMGCR was evaluated by western blotting. In addition, the cholesterol level of the optic nerve was assessed. The retina was excised and the surviving RGCs were observed and counted. The morphology of the RGCs in the rat model of optic nerve injury changed; however, the degree of damage in rats treated with resveratrol was relatively small. The number of surviving RGCs and the cholesterol level in the RGCs from the model rats was observed to be restored by treatment with resveratrol following optic nerve damage. Additionally, the expression levels of SIRT1, SREBP‑2 and HMGCR mRNA and protein were restored by resveratrol treatment in the rats with optic nerve damage. Thus, resveratrol reversed certain features of the optic nerve injury damage via SIRT1 and SREBP‑2‑associated signaling pathways and the downstream regulated gene, HMGCR. Furthermore, resveratrol promoted cholesterol synthesis in, and repair of, RGCs. Therefore, SIRT1 may serve as a promising novel target for the treatment of optic nerve damage.

Astragalus polysaccharides affect insulin resistance by regulating the hepatic SIRT1-PGC-1α/PPARα-FGF21 signaling pathway in male Sprague Dawley rats undergoing catch-up growth.

The present study investigated the effects of Astragalus polysaccharides (APS) on insulin resistance by modulation of hepatic sirtuin 1 (SIRT1)-peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)-1α/PPARα-fibroblast growth factor (FGF)21, and glucose and lipid metabolism. Thirty male Sprague Dawley rats were divided into three groups: A normal control group, a catch-up growth group and an APS-treated (APS-G) group. The latter two groups underwent food restriction for 4 weeks, prior to being provided with a high fat diet, which was available ad libitum. The APS-G group was orally treated with APS for 8 weeks, whereas the other groups were administered saline. Body weight was measured and an oral glucose tolerance test (OGTT) was conducted after 8 weeks. The plasma glucose and insulin levels obtained from the OGTT were assayed, and hepatic morphology was observed by light and transmission electron microscopy. In addition, the mRNA expression levels of PGC-1α/PPARα, and the protein expression levels of SIRT1, FGF21 and nuclear factor-κB were quantified in the liver and serum. APS treatment suppressed abnormal glycolipid metabolism and insulin resistance following 8 weeks of catch-up growth by improving hepatic SIRT1-PPARα-FGF21 intracellular signaling and reducing chronic inflammation, and by partially attenuating hepatic steatosis. The suppressive effects of APS on liver acetylation and glycolipid metabolism-associated molecules contributed to the observed suppression of insulin resistance. However, the mechanism underlying the effects of APS on insulin resistance requires further research in order to be elucidated. Rapid and long-term treatment with APS may provide a novel, safe and effective therapeutic strategy for type 2 diabetes.

Resveratrol relieves ischemia-induced oxidative stress in the hippocampus by activating SIRT1.

Resveratrol, a naturally occurring phytoalexin, acts as an activator of sirtuin 1 (SIRT1) and has been shown to have a neuroprotective role in various models. Healthy adult male Sprague-Dawley rats were subjected to cerebral ischemia in order to study the protective effect of resveratrol on the brain following ischemia, and to investigate the effects of SIRT1 activation on the hippocampus. Untreated and resveratrol-treated rats were anesthetized prior to undergoing surgery to induce middle cerebral artery occlusion followed by reperfusion. SIRT1 expression was evaluated by immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction, and SIRT1 activity was also evaluated. In addition, terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) and Nissl staining assays were conducted and the levels of reactive oxygen species were determined. It was observed that resveratrol significantly decreased the number of TUNEL-positive cells and increased the expression of SIRT1 mRNA in a dose-dependent manner. This was accompanied by increases in SIRT1 protein expression levels and SIRT1 activity. The results demonstrate the neuroprotective and antioxidant effects of resveratrol against ischemia-induced apoptosis in the rat hippocampus.

Differential Telomere Shortening in Blood versus Arteries in an Animal Model of Type 2 Diabetes.

Vascular dysfunction is an early feature of diabetic vascular disease, due to increased oxidative stress and reduced nitric oxide (NO) bioavailability. This can lead to endothelial cell senescence and clinical complications such as stroke. Cells can become senescent by shortened telomeres and oxidative stress is known to accelerate telomere attrition. Sirtuin 1 (SIRT1) has been linked to vascular health by upregulating endothelial nitric oxide synthase (eNOS), suppressing oxidative stress, and attenuating telomere shortening. Accelerated leukocyte telomere attrition appears to be a feature of clinical type 2 diabetes (T2D) and therefore the telomere system may be a potential therapeutic target in preventing vascular complications of T2D. However the effect of T2D on vascular telomere length is currently unknown. We hypothesized that T2D gives rise to shortened leukocyte and vascular telomeres alongside reduced vascular SIRT1 expression and increased oxidative stress. Accelerated telomere attrition was observed in circulating leukocytes, but not arteries, in T2D compared to control rats. T2D rats had blunted arterial SIRT1 and eNOS protein expression levels which were associated with reduced antioxidant defense capacity. Our findings suggest that hyperglycemia and a deficit in vascular SIRT1 per se are not sufficient to prematurely shorten vascular telomeres.