NAD+ mediated photoelectrochemical biosensor for histone deacetylase Sirt1 detection based on CuO-BiVO4-AgNCs heterojunction and hybridization chain reaction amplification.

BACKGROUND: Histone deacetylate Sirt1 has been involved in many important biological processes and is closely related to the occurrence and development of many diseases. Therefore, the accurate detection of Sirt1 is of great significance for the diagnosis and treatment of diseases caused by Sirt1 and the development of related drugs. RESULTS: In this work, a photoelectrochemical biosensor was developed for Sirt1 detection based on the NAD + mediated Sirt1 recognition and E. Coli DNA ligase activity. CuO-BiVO4p-n heterojunction was employed as the photoactive material, rolling circle amplification (RCA), hybridization chain reaction (HCR) and AgNCs were used as triple signal amplifications. As a bifunctional cofactor, NAD+ played a crucial role for Sirt1 detection, where the peptide deacetylation catalyzed by Sirt1 consumed NAD+, and the decreased amount of NAD + inhibited the activity of E. Coli DNA ligase, leading to the failure on RCA reaction, and improving the HCR reaction. Finally, AgNCs were generated using C-rich DNA as carrier. The surface plasmon effect of AgNCs and its heterojunction with CuO and BiVO4 accelerated the transfer rate of photogenerated carriers and improved the photocurrent signal. When the detection range was 0.001-200 nM, the detection limit of the biosensor was 0.76 pM (S/N = 3). SIGNIFICANCE: The applicability of the method was evaluated by studying the effects of known inhibitors nicotinamide and environmental pollutant halogenated carbazole on Sirt1 enzyme activity. The results showed that this method can be used as a new platform for screening Sirt1 enzyme inhibitors, and also provided a new biomarker for evaluating the ecotoxicological effects of environmental pollutants.

Activation of SIRT1 ameliorates LPS-induced lung injury in mice via decreasing endothelial tight junction permeability.

The integrity of the endothelial barrier is a determinant of the prognosis of lipopolysaccharide (LPS)-induced acute lung injury (ALI). In this study, we investigated whether and how Sirtuin 1 (SIRT1) maintained the vascular integrity during ALI. An experimental model of ALI was established in mice through intratracheal administration of LPS (10 mg/kg). LPS stimulation significantly increased the pulmonary permeability and decreased the expression of SIRT1 and tight junction proteins (TJs), including occludin, claudin-5, tight junction protein 1 and tight junction protein 2. Morphological studies showed that LPS induced obvious lung injury with inflammatory cell infiltration in the interstitial and alveolar space, hemorrhage, edema, and the thickened alveolar wall compared to the control mice. Intratracheal administration of the selective SIRT1 activator SRT1720 (6.25 mg/kg) significantly attenuated LPS-induced lung injury, lung hyper-permeability and increased TJs expression, whereas intratracheal administration of the selective SIRT1 inhibitor EX527 (6.25 mg/kg) aggravated LPS-induced ALI. Similar protective effects of SIRT1 on pulmonary cellular permeability were observed in primary human pulmonary microvascular endothelial cells treated with LPS (2 mg/mL) in vitro. We further demonstrated that the RhoA/ROCK signaling pathway was activated in SIRT1 regulation of tight junction permeability. The RhoA/ROCK inhibitor Y-27632 (10 µM) increased the expression of TJs and reversed LPS- or EX527-induced hyper-permeability. In conclusion, SIRT1 ameliorates LPS-induced lung injury via decreasing endothelial tight junction permeability, possibly via RhoA/ROCK signaling pathway. This finding may contribute to the development of new therapeutic approaches for lung injury.

Anti-nociceptive effects of caloric restriction on neuropathic pain in rats involves silent information regulator 1.

BACKGROUND: Caloric restriction (CR) increases both average and maximum lifespan, retards physiological signs of ageing, and delays the onset of several diseases and may mediate neuropathic pain. Neuropathic pain seriously affects the quality of life of patients. In this study, we investigated whether CR exerts anti-nociceptive effects on neuropathic pain, and probed its potential mechanisms. METHODS: Adult rats were divided into two dietary groups: an ad libitum (AL)-fed group and a CR group, which was provided with 60% of the food intake of AL rats for 6 weeks. The effects of 6-week CR on pain behaviour and neuro-inflammation induced by chronic constriction injury of the sciatic nerve were evaluated. RESULTS: Rats subjected to a CR diet had reduced hypersensitivity to mechanical and thermal stimuli after nerve-constriction injury. CR increased the silent information regulator 1 (SIRT1) expression, and suppressed the nerve-constriction-induced production of mitochondrial-derived reactive oxygen species and activation of nuclear factor kappa B accompanied by suppression of mature interleukin-1ß production in the ipsilateral spinal cord dorsal horn. The inhibition of SIRT1 reversed the effects of caloric restriction on pain behaviours. Moreover, CR decreased the phosphorylation of N-methyl-d-aspartate receptor subunits and the mitogen-activated protein kinase family, decreased the sensory neurone excitability, and inhibited the nerve-constriction-induced glial-cell activation. CONCLUSIONS: These results suggest that the effects of CR on pain behaviours in a rat model of nerve injury are via inhibition of excessive neuro-inflammation induced by the injury. CR may be of benefit in patients with neuropathic pain.

Dihydroartemisinin enhances antitumor effect of 5-fluorouracil against gastric cancer by down-regulating SIRT1 expression / 中国病理生理杂志

AIM:To investigate the effect of dihydroartemisinin ( DHA) adjuvant treatment on enhancing the antitumor effect of 5-fluorouracil (5-FU) against gastric cancer .METHODS:The gastric cancer BGC-823 cells were di-vided into control group , DHA group, 5-FU group, 5-FU+DHA group and 5-FU+DHA+SIRT1 plasmid group.The via-bility of BGC-823 cells treated with DHA and 5-FU was measured by MTT assay .The expression of SIRT1 and NADPH ox-idase, activation of caspase-9 and caspase-3, and phosphorylation of ASK1 and JNK in the BGC-823 cells treated with DHA and 5-FU were determined by Western blot .The production of ROS and the apoptosis of the BGC-823 cells treated with DHA and 5-FU were analyzed by flow cytometry .RESULTS:Dihydroartemisinin significantly inhibited the expression of SIRT1 and increased NADPH oxidase protein level (P<0.05).DHA increased the sensitivity of BGC-823 cells to 5-FU, thus decreasing the IC50 of 5-FU to the gastric cancer cells.However, transfection with SIRT1 plasmid decreased the cytotoxicity of DHA and 5-FU co-treatment to the BGC-823 cells.DHA promoted the production of ROS and phosphoryla-tion of ASK1 and JNK induced by 5-FU in the BGC-823 cells ( P<0.05 ) .However , ROS scavenger N-acetylcysteine ( NAC) or JNK specific inhibitor SP600125 inhibited the cell death and activation of caspase-9 and caspase-3 induced by DHA and 5-FU co-treatment (P<0.05).In addition, NAC significantly inhibited the phosphorylation of JNK in the BGC-823 cells co-treated with DHA and 5-FU.However, treatment with SP600125 did not influence the ROS production in the BGC-823 cells, indicating that JNK was the downstream target of ROS pathway .CONCLUSION: Combination of DHA with 5-FU induces caspase-dependent apoptosis in gastric cancer cells through the SIRT 1/NADPH oxidase/ROS/JNK sig-naling pathway .

Effects of Sirt1 gene knockout on chronic kidney disease induced by 5/6 nephrectomy in mice and VEGF/Flk-1 signaling pathway / 中华肾脏病杂志

Objective To investigate the effect of Sirt1 gene knockout on chronic kidney disease induced by 5/6 nephrectomy in mice and vascular endothelial growth factor (VEGF)/fetal liver kinase-1 (Flk-1) signaling pathway.Methods Twenty four male Sirt1 +/+ and Sirt1 +/-mice wererandomly divided into four groups:Sirt1+/+ mice with sham-operation (WT-Sham,n=6),Sirt1+/-mice with sham-operation (KO-Sham,n=6),Sirt1 +/+ mice with 5/6 nephrectomy (WT-Nx,n=6) and Sirt1 +/-mice with 5/6 nephrectomy (KO-Nx,n=6).Proteinuria was determined by urine collection from 8:00 to 8:00 the next day at 20 weeks.Serum creatinine (Scr),urea nitrogen (BUN) and the renal pathological changes were measured after 20 weeks.Expressions of Sirt1,collagen Ⅰ and transforming growth factor β(TGF-β) were used to analyze the changes of renal fibrosis by immunohistochemistry staining.Real-time PCR and Western blotting were used to measure the mRNA and protein expressions of Sirt1,fibronectin,collagen Ⅰ,VEGF and Flk-1 in kidney.Results Sirt1 expressed in glomernlar endothelial cells,podocytes,mesangial cells and renal tubular epithelial cells in Sirt1 +/+ mice,while Sirt1 expression intensity was significantly reduced in Sirt1 +/-mice.Compared with the WT-Sham group,WT-Nx group had increased proteinuria,BUN,Scr,glomernlar sclerosis index and tubulointerstitial fibrosis index at 12 weeks after operation (all P ＜ 0.01),and KO-Nx group had exacerbated the above up-regulations (all P ＜ 0.01).Compared with those in WT-Sham group,the expressions of fibronectin,collagen Ⅰ and TGF-β were up-regulated in WT-Nx group (all P ＜ 0.01),and were significantly augmented in KO-Nx group (all P ＜ 0.01).Compared with those in WT-Sham group,renal mRNA and protein expressions of VEGF and Flk-1 were decreased in WT-Nx group,and KO-Nx group aggravated their down-regulation (all P ＜ 0.01).Conclusions Sirt1 gene knockout can increase proteinuria and Scr,and aggravate renal pathology and renal fibrosis in 5/6 nephrectomized mice,which is associated with the inhibition of VEGF/Flk-1 signaling pathway.It is suggested that Sirt1 may be a potential therapeutic target of chronic kidney disease.

Monocrotaline-Induced Pulmonary Hypertension Involves Downregulation of Antiaging Protein Klotho and eNOS Activity.

The objective of this study is to investigate whether stem cell delivery of secreted Klotho (SKL), an aging-suppressor protein, attenuates monocrotaline-induced pulmonary vascular dysfunction and remodeling. Overexpression of SKL in mesenchymal stem cells (MSCs) was achieved by transfecting MSCs with lentiviral vectors expressing SKL-green fluorescent protein (GFP). Four groups of rats were treated with monocrotaline, whereas an additional group was given saline (control). Three days later, 4 monocrotaline-treated groups received intravenous delivery of nontransfected MSCs, MSC-GFP, MSC-SKL-GFP, and PBS, respectively. Ex vivo vascular relaxing responses to acetylcholine were diminished in small pulmonary arteries (PAs) in monocrotaline-treated rats, indicating pulmonary vascular endothelial dysfunction. Interestingly, delivery of MSCs overexpressing SKL (MSC-SKL-GFP) abolished monocrotaline-induced pulmonary vascular endothelial dysfunction and PA remodeling. Monocrotaline significantly increased right ventricular systolic blood pressure, which was attenuated significantly by MSC-SKL-GFP, indicating improved PA hypertension. MSC-SKL-GFP also attenuated right ventricular hypertrophy. Nontransfected MSCs slightly, but not significantly, improved PA hypertension and pulmonary vascular endothelial dysfunction. MSC-SKL-GFP attenuated monocrotaline-induced inflammation, as evidenced by decreased macrophage infiltration around PAs. MSC-SKL-GFP increased SKL levels, which rescued the downregulation of SIRT1 (Sirtuin 1) expression and endothelial NO synthase (eNOS) phosphorylation in the lungs of monocrotaline-treated rats. In cultured endothelial cells, SKL abolished monocrotaline-induced downregulation of eNOS activity and NO levels and enhanced cell viability. Therefore, stem cell delivery of SKL is an effective therapeutic strategy for pulmonary vascular endothelial dysfunction and PA remodeling. SKL attenuates monocrotaline-induced PA remodeling and PA smooth muscle cell proliferation, likely by reducing inflammation and restoring SIRT1 levels and eNOS activity.

Age-Associated Sirtuin 1 Reduction in Vascular Smooth Muscle Links Vascular Senescence and Inflammation to Abdominal Aortic Aneurysm.

RATIONALE: Uncontrolled growth of abdominal aortic aneurysms (AAAs) is a life-threatening vascular disease without an effective pharmaceutical treatment. AAA incidence dramatically increases with advancing age in men. However, the molecular mechanisms by which aging predisposes individuals to AAAs remain unknown. OBJECTIVE: In this study, we investigated the role of SIRT1 (Sirtuin 1), a class III histone deacetylase, in AAA formation and the underlying mechanisms linking vascular senescence and inflammation. METHODS AND RESULTS: The expression and activity of SIRT1 were significantly decreased in human AAA samples. SIRT1 in vascular smooth muscle cells was remarkably downregulated in the suprarenal aortas of aged mice, in which AAAs induced by angiotensin II infusion were significantly elevated. Moreover, vascular smooth muscle cell-specific knockout of SIRT1 accelerated angiotensin II-induced formation and rupture of AAAs and AAA-related pathological changes, whereas vascular smooth muscle cell-specific overexpression of SIRT1 suppressed angiotensin II-induced AAA formation and progression in Apoe-/- mice. Furthermore, the inhibitory effect of SIRT1 on AAA formation was also proved in a calcium chloride (CaCl2)-induced AAA model. Mechanistically, the reduction of SIRT1 was shown to increase vascular cell senescence and upregulate p21 expression, as well as enhance vascular inflammation. Notably, inhibition of p21-dependent vascular cell senescence by SIRT1 blocked angiotensin II-induced nuclear factor-κB binding on the promoter of monocyte chemoattractant protein-1 and inhibited its expression. CONCLUSIONS: These findings provide evidence that SIRT1 reduction links vascular senescence and inflammation to AAAs and that SIRT1 in vascular smooth muscle cells provides a therapeutic target for the prevention of AAA formation.

Altered expression of micro-RNA 199a and increased levels of cardiac SIRT1 protein are associated with the occurrence of atrial fibrillation after coronary artery bypass graft surgery.

BACKGROUND: Postoperative atrial fibrillation (POAF) is a potentially life-threatening complication after coronary artery bypass graft (CABG) surgery. The expression of the cardioprotective SIRT1 protein with its antioxidant activity is increased in cardiac tissue of patients suffering from POAF. So far, information is lacking about the relationship between SIRT1 regulating micro RNAs (miRs), SIRT1 protein and the occurrence of POAF. METHODS: A total of 63 patients undergoing CABG were recruited, and biopsies were obtained from the right atrial appendage during cannulation. Postoperative, all patients were rhythm-monitored until discharge and randomized to POAF (n=20) or sinus rhythm (n=43). The expression of the micro RNAs miR-199a and miR-195 was quantified by real-time PCR. SIRT1 protein was detected by western blot analysis. RESULTS: The relative expression of miR-199a in the POAF group was significantly decreased compared to the control group (0.77±0.27 vs. 1.11±0.69, P=.022) Accordingly, SIRT 1 protein was significantly induced in tissue probes of patients with POAF (P<.001). CONCLUSION: Altered expression of the SIRT1 protein regulating miR-199a in human atrial tissue was found to be related to the occurrence of POAF, indicating its usefulness as a biomarker for cardiac surgery management.

Forkhead Transcription Factor FOXO1 Inhibits Angiogenesis in Gastric Cancer in Relation to SIRT1.

PURPOSE: We previously reported that forkhead transcription factors of the O class 1 (FOXO1) expression in gastric cancer (GC) was associated with angiogenesis-related molecules. However, there is little experimental evidence for the direct role of FOXO1 in GC. In the present study, we investigated the effect of FOXO1 on the tumorigenesis and angiogenesis in GC and its relationship with SIRT1. MATERIALS AND METHODS: Stable GC cell lines (SNU-638 and SNU-601) infected with a lentivirus containing FOXO1 shRNA were established for animal studies as well as cell culture experiments. We used xenograft tumors in nude mice to evaluate the effect of FOXO1 silencing on tumor growth and angiogenesis. In addition, we examined the association between FOXO1 and SIRT1 by immunohistochemical tissue array analysis of 471 human GC specimens and Western blot analysis of xenografted tumor tissues. RESULTS: In cell culture, FOXO1 silencing enhanced hypoxia inducible factor-1α (HIF-1α) expression and GC cell growth under hypoxic conditions, but not under normoxic conditions. The xenograft study showed that FOXO1 downregulation enhanced tumor growth, microvessel areas, HIF-1α activation and vascular endothelial growth factor (VEGF) expression. In addition, inactivated FOXO1 expression was associated with SIRT1 expression in human GC tissues and xenograft tumor tissues. CONCLUSION: Our results indicate that FOXO1 inhibits GC growth and angiogenesis under hypoxic conditions via inactivation of the HIF-1α-VEGF pathway, possibly in association with SIRT1. Thus, development of treatment modalities aiming at this pathway might be useful for treating GC.

Forkhead Transcription Factor FOXO1 Inhibits Angiogenesis in Gastric Cancer in Relation to SIRT1 / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: We previously reported that forkhead transcription factors of the O class 1 (FOXO1) expression in gastric cancer (GC) was associated with angiogenesis-related molecules. However, there is little experimental evidence for the direct role of FOXO1 in GC. In the present study, we investigated the effect of FOXO1 on the tumorigenesis and angiogenesis in GC and its relationship with SIRT1. MATERIALS AND METHODS: Stable GC cell lines (SNU-638 and SNU-601) infected with a lentivirus containing FOXO1 shRNA were established for animal studies as well as cell culture experiments. We used xenograft tumors in nude mice to evaluate the effect of FOXO1 silencing on tumor growth and angiogenesis. In addition, we examined the association between FOXO1 and SIRT1 by immunohistochemical tissue array analysis of 471 human GC specimens and Western blot analysis of xenografted tumor tissues. RESULTS: In cell culture, FOXO1 silencing enhanced hypoxia inducible factor-1alpha (HIF-1alpha) expression and GC cell growth under hypoxic conditions, but not under normoxic conditions. The xenograft study showed that FOXO1 downregulation enhanced tumor growth, microvessel areas, HIF-1alpha activation and vascular endothelial growth factor (VEGF) expression. In addition, inactivated FOXO1 expression was associated with SIRT1 expression in human GC tissues and xenograft tumor tissues. CONCLUSION: Our results indicate that FOXO1 inhibits GC growth and angiogenesis under hypoxic conditions via inactivation of the HIF-1alpha-VEGF pathway, possibly in association with SIRT1. Thus, development of treatment modalities aiming at this pathway might be useful for treating GC.

MicroRNA-mediated epigenetic silencing of sirtuin1 contributes to impaired angiogenic responses.

RATIONALE: Transforming growth factor (TGF)-ß was linked to abnormal vessel function and can mediate impairment of endothelial angiogenic responses. Its effect on microRNAs and downstream targets in this context is not known. OBJECTIVE: To study the role of microRNAs in TGF-ß-mediated angiogenic activity. METHODS AND RESULTS: MicroRNA profiling after TGF-ß treatment of endothelial cells identified miR-30a-3p, along with other members of the miR-30 family, to be strongly silenced. Supplementation of miR-30a-3p restored function in TGF-ß-treated endothelial cells. We identified the epigenetic factor methyl-CpG-binding protein 2 (MeCP2) to be a direct and functional target of miR-30a-3p. Viral overexpression of MeCP2 mimicked the effects of TGF-ß, suggesting that derepression of MeCP2 after TGF-ß treatment may be responsible for impaired angiogenic responses. Silencing of MeCP2 rescued detrimental TGF-ß effects on endothelial cells. Microarray transcriptome analysis of MeCP2-overexpressing endothelial cells identified several deregulated genes important for endothelial cell function including sirtuin1 (Sirt1). In vivo experiments using endothelial cell-specific MeCP2 null or Sirt1 transgenic mice confirmed the involvement of MeCP2/Sirt1 in the regulation of angiogenic functions of endothelial cells. Additional experiments identified that MeCP2 inhibited endothelial angiogenic characteristics partly by epigenetic silencing of Sirt1. CONCLUSIONS: TGF-ß impairs endothelial angiogenic responses partly by downregulating miR-30a-3p and subsequent derepression of MeCP2-mediated epigenetic silencing of Sirt1.

Expression of SIRT1 and DBC1 in Gastric Adenocarcinoma.

BACKGROUND: Sirtuin 1 (SIRT1) and deleted in breast cancer 1 (DBC1) are known as tumor suppressor or promoter genes. This may be due to their diverse functions and interaction with other proteins. Gastric adenocarcinoma is one of the most common malignancies, but little is known about its carcinogenesis. Therefore, we investigated the association of immunohistochemical expression of SIRT1, DBC1, p53, and ß-catenin and their variable clinicopathological characteristics. METHODS: We obtained samples from 452 patients who underwent gastrectomy. Tissue microarray blocks were constructed and immonohistochemical staining was performed. RESULTS: Expression of DBC1 and SIRT1 was associated with lower histologic grade, intestinal type of Lauren classification, and lower pT (p<0.001) and pN stage (DBC1, p=0.002; SIRT1, p<0.001). Association between absence of lymphatic invasion, and SIRT1 (p=0.001) and DBC1 (p=0.004) was observed. Cytoplasmic ß-catenin expression was associated with lower histologic grade, pT, pN, tumor-node-metastasis (TNM) stage, DBC1 (p<0.001), and SIRT1 (p=0.001). Expression of SIRT1 and DBC1 was not associated with p53 (p=0.063 and p=0.060). DBC1 was an independent good prognostic factor in multivariate analysis (p=0.012). CONCLUSIONS: SIRC1 and DBC1 can be considered to be good prognostic factors in gastric adenocarcinoma.

Expression of SIRT1 and DBC1 in Gastric Adenocarcinoma

BACKGROUND: Sirtuin 1 (SIRT1) and deleted in breast cancer 1 (DBC1) are known as tumor suppressor or promoter genes. This may be due to their diverse functions and interaction with other proteins. Gastric adenocarcinoma is one of the most common malignancies, but little is known about its carcinogenesis. Therefore, we investigated the association of immunohistochemical expression of SIRT1, DBC1, p53, and beta-catenin and their variable clinicopathological characteristics. METHODS: We obtained samples from 452 patients who underwent gastrectomy. Tissue microarray blocks were constructed and immonohistochemical staining was performed. RESULTS: Expression of DBC1 and SIRT1 was associated with lower histologic grade, intestinal type of Lauren classification, and lower pT (p<0.001) and pN stage (DBC1, p=0.002; SIRT1, p<0.001). Association between absence of lymphatic invasion, and SIRT1 (p=0.001) and DBC1 (p=0.004) was observed. Cytoplasmic beta-catenin expression was associated with lower histologic grade, pT, pN, tumor-node-metastasis (TNM) stage, DBC1 (p<0.001), and SIRT1 (p=0.001). Expression of SIRT1 and DBC1 was not associated with p53 (p=0.063 and p=0.060). DBC1 was an independent good prognostic factor in multivariate analysis (p=0.012). CONCLUSIONS: SIRC1 and DBC1 can be considered to be good prognostic factors in gastric adenocarcinoma.

SIRT1 promotes DNA repair activity and deacetylation of Ku70

Human SIRT1 controls various physiological responses including cell fate, stress, and aging, through deacetylation of its specific substrate protein. In processing DNA damage signaling, SIRT1 attenuates a cellular apoptotic response by deacetylation of p53 tumor suppressor. The present study shows that, upon exposure to radiation, SIRT1 could enhance DNA repair capacity and deacetylation of repair protein Ku70. Ectopically over-expressed SIRT1 resulted in the increase of repair of DNA strand breakages produced by radiation. On the other hand, repression of endogenous SIRT1 expression by SIRT1 siRNA led to the decrease of this repair activity, indicating that SIRT1 can regulate DNA repair capacity of cells with DNA strand breaks. In addition, we found that SIRT1 physically complexed with repair protein Ku70, leading to subsequent deacetylation. The dominant-negative SIRT1, a catalytically inactive form, did not induce deacetylation of Ku70 protein as well as increase of DNA repair capacity. These observations suggest that SIRT1 modulates DNA repair activity, which could be regulated by the acetylation status of repair protein Ku70 following DNA damage.