SIRT3 Level Research Articles

Sirtuin3 and Sirtuin7 are promising biomarkers in systemic sclerosis

BackgroundSystemic sclerosis (SSc) is an autoimmune disease that results in micro-vasculopathy, leading to organ dysfunction. Sirtuins are known for their role in cellular processes such as the cell cycle, aging, and inflammation, Sirtuins also play an important role in regulating fibrotic responses, inhibiting collagen production and myofibroblast differentiation, implying that its dysregulation is involved in the pathogenesis of systemic sclerosis. The aim of this study was to determine the circulating Sirtuin3 and Sirtuin7 levels in patients suffering from systemic sclerosis with a focus on how they might be associated with the different clinical features and subsets of the disease.MethodsThis prospective cross-sectional case–control study included 56 participants 41 SSc patients and 15 healthy controls. Demographics, clinical, and laboratory data were analyzed. Quantitative determination of human Sirtuin3 and Sirtuin7 concentrations was done.ResultsAmong systemic sclerosis patients, the age of SSc patients was 42.27 ± 10.46 years. The mean serum levels of Sirtuin3 and Sirtuin7 were significantly lower in SSc patients than in healthy controls (p < 0.001). SIRT3 and SIRT7 levels among SSc patients showed a statistically significant positive correlation (p < 0.001). SIRT7 level was insignificantly decreased in dcSSc (14.16 ± 5.93) than in lcSSc (20.01 ± 8.34). Regarding the SIRT3 level, there was an insignificant difference between dcSSc and lcSSc. Modified Rodnan’s skin score correlated negatively with Sirtuin3 and Sirtuin7 levels. In systemic sclerosis patients with interstitial lung disease (56.1%), there was an insignificant difference in SIRT3 and SIRT7 levels (0.12 ± 0.01and 21.23 ± 8.23) compared with systemic sclerosis patients without interstitial lung disease (0.10 ± 0.01 and 17.47 ± 8.57), with p = 0.408 and 0.258, respectively. The receiver operating characteristic curve for SSc prediction with Sirtuin3 has an accuracy of 83.0%, sensitivity of 85.4%, and specificity of 80.0% and p < 0.001. Regarding Sirtuin7, it has an accuracy of 89.5%, sensitivity of 85.4%, and specificity of 93.3% and p < 0.001.ConclusionSirtuin3 and Sirtuin7 levels were found to have a significant positive correlation in SSc patients. Sirtuin3 and Sirtuin7 levels are both good diagnostic biomarkers for detecting and diagnosing SSc, with Sirtuin7 being more accurate, specific, and predictive of the disease than Sirtuin3. Sirtuin7 is thought to be a new biomarker for SSc disease.

Sex-related differences in SIRT3-mediated mitochondrial dynamics in renal ischemia/reperfusion injury

The prevalence of renal ischemia/reperfusion injury (IRI) in premenopausal women is considerably lower than that in age-matched men. This suggests that sex-related differences in mitochondrial function and homeostasis may contribute to sexual dimorphism in renal injury, though the mechanism remains unclear. Mouse model of unilateral left renal IRI with contralateral kidney enucleation, Ovariectomy in female mice, and a human embryonic kidney (HEK) cell model of hypoxia-reoxygenation were used to study how estrogen affects the sexual dimorphism of renal IRI through SIRT3 in vitro and in vivo, respectively. Here, we demonstrate differential expression of renal SIRT3 may induce sexual dimorphism in IRI using the renal IRI model. Higher SIRT3 level in female mice was associated with E2-induced protection of renal tubular epithelium, reduced mitochondrial reactive oxygen species (ROS), and IRI resistance. In hypoxia-reoxygenated HEK cells, SIRT3 knockdown increased oxidative stress, shifted the interconnected mitochondrial network toward fission, exacerbated hypoxia/reoxygenation-induced endoplasmic reticulum stress (ERS), and abolished the protective effects of E2 on IRI. Mechanistically, the SIRT3 level is E2-dependent and that E2 increases the SIRT3 protein level via estrogen receptor. SIRT3 targeted an i-AAA protease, yeast mitochondrial AAA metalloprotease (YME1L1), and hydrolyzed long optic atrophy 1 (L-OPA) to short-OPA1 (S-OPA1) by deacetylating YME1L1, regulating mitochondrial dynamics toward fusion to reduce oxidative stress and ERS. These findings explored the mechanism by how estrogen alleviates renal IRI and providing a basis for potential therapeutic interventions targeting SIRT3.

Effect of electroacupuncture treatment combined with rehabilitation care on serum sirt3 level and motor function in elderly patients with stroke hemiparesis.

Acupuncture treatment helps to improve neurological and motor function in elderly patients with stroke hemiplegia. However, the exact mechanism by which electroacupuncture improves stroke hemiparesis is uncertain. The aim of this study was to determine the effect of electroacupuncture care on sirt3 levels in elderly patients with stroke hemiparesis. One hundred and ten elderly patients with hemiplegia after first stroke were divided into an experimental group and a control group (n = 55 in each group). The control group was given conventional rehabilitation care by a rehabilitation therapist. In the experimental group, on the basis of conventional rehabilitation care, electroacupuncture was performed once a day for 28 days. Fugl-Meyer assessment (FMA) and barthel index (BI) scores were significantly higher, while neurologic deficit scale (NDS) and physiological state scores were significantly lower in both groups after 14 and 28 days of intervention compared to preintervention. The Generalized estimating equation (GEE) model also showed that the experimental group showed more favorable improvements in all outcomes at postintervention time points compared to the control group. After the intervention, serum sirt3 levels increased significantly in both groups compared to preintervention, and the increase was more pronounced in the experimental group. Consistently, the GEE model showed that serum sirt3 levels were significantly higher in the experimental group compared to the control group at postintervention time points. Correlation analysis revealed that serum sirt3 levels in the experimental group were negatively correlated with FMA and BI pre- and postintervention, while showing a significant positive correlation with NDS and physiological state scores. Electroacupuncture intervention led to significant improvements in motor function, activities of daily living and neurological function in elderly patients with stroke hemiplegia, which may be associate with increased serum sirt3 levels.

Intermittent cold exposure upregulates regulators of cardiac mitochondrial biogenesis and function in mice.

Hypothermic conditions enhance the incidence of cardiovascular diseases due to increased blood pressure. Cold-induced adaptive thermogenesis increased mitochondrial biogenesis and function in skeletal muscles and adipocytes. Here, we studied the effect of intermittent cold exposure on the regulators of cardiac mitochondrial biogenesis, function, and its regulation by SIRT-3. Intermittent cold exposed mice hearts showed normal histopathology with increased mitochondrial antioxidant and metabolic function, as evidenced by an increase in the activity and expression of MnSOD and SDH. A substantial increase in mitochondrial DNA copy number and increase in the expression of PGC-1α and its downstream targets NRF-1 and Tfam indicated the possibility of enhanced cardiac mitochondrial biogenesis and function on intermittent cold exposure. Increased mitochondrial SIRT-3 level and decreased total protein lysine acetylation indicate increased sirtuin activity in cold exposed mice hearts. Ex vivo cold mimic using norepinephrine showed a significant increase in PGC-1α, NRF-1, and Tfam levels. AGK-7, a SIRT-3 inhibitor, reversed the norepinephrine-induced upregulation of PGC-1α and NRF-1, indicating the role ofSIRT-3 on the production of PGC-1α and NRF-1. Inhibition of PKA with KT5720 in norepinephrine treated cardiac tissue slices indicates the role of PKA in regulating the production of PGC-1α and NRF-1. In conclusion, intermittent cold exposure upregulated the regulators of mitochondrial biogenesis and function through PKA and SIRT-3 mediated pathway. Our results emphasize the role of intermittent cold-induced adaptive thermogenesis in overcoming chronic cold-induced cardiac damage.

Sirtuin3 Alleviated Influenza A Virus-Induced Mitochondrial Oxidative Stress and Inflammation in Lung Epithelial Cells via Regulating Poly (ADP-Ribose) Polymerase 1 Activity

Introduction: Influenza A virus (IAV) infection causes severe lung inflammation and injury, particularly in children. Sirtuin3 (Sirt3) was confirmed to be effective in protecting the lung against injury. This study aims to explore the function and mechanism of Sirt3 on influenza development in children. Methods: The Sirt3 level in serum samples from IAV-infected children and lung epithelial cells were detected using RT-qPCR, ELISA, and Western blot assays. Cell viability and apoptosis were determined by MTT and flow cytometry assays. Virus titration was conducted by determining TCID₅₀. Cell inflammatory response was detected by a battery of inflammatory cytokines. The contents of ROS and ATP, mitochondrial membrane potential level, and oxygen-consumption rate were examined to reflect on oxidative stress and mitochondrial dysfunction. The activity of poly (ADP-ribose) polymerase 1 (PARP-1) was measured by colorimetry. Results: Sirt3 was downregulated in IAV-infected children’s serum samples and BEAS-2B cells. Overexpression of Sirt3 alleviated IAV replication and IAV-induced inflammatory injury, oxidative stress, and mitochondrial dysfunction in lung epithelial cells. Moreover, upregulation of Sirt3 deacetylated SOD2 and PARP-1 and inhibited the PARP-1 activity. Notably, the Sirt3 inhibitor (3-TYP) and PARP-1 activity agonist (nicotinamide) reversed the effects of Sirt3 overexpression on IAV replication and IAV-induced injury. Conclusion: Overexpression of Sirt3 attenuated IAV-evoked inflammatory injury and mitochondrial oxidative stress through the inhibition of PARP-1 activity in lung epithelial cells.

Abstract 13621: Genetic and Pharmacological Induction of Endothelial Sirt3 After Onset of Hypertension Rescues Endothelial Function

Endothelial dysfunction plays critical role in the pathogenesis of hypertension and atherosclerosis. These pathological conditions are main risk factors for cardiovascular disease killing 700,000 people every year in US alone. We discovered a new control point with the potential to address this problem. We have shown that Sirt3 level is reduced in essential hypertension and endothelial Sirt3 overexpression attenuates endothelial dysfunction and hypertension. We proposed induction of endothelial Sirt3 after onset of hypertension to rescue endothelial function and reduce hypertension. To test the hypothesis, we used genetic- and pharmacological Sirt3 activation. To genetically induce the expression of endothelial Sirt3 we used Sirt3 flox/flox mice crossed with VeCad-Cre mice treated with low dose of 4-hydroxytamoxifen (4HOT, i.p. 0.3 mg/20 g daily, 5 days) which does not have off-target cardiovascular effects. Mice underwent telemetry placement and ten days later received 4-week osmotic pumps containing vehicle (saline) or angiotensin II (0.7 mg/kg/day). 14-days later half of mice received 4HOT to induce endothelial Sirt3 overexpression. Treatment of mice with 4HOT after onset of hypertension slightly reduced blood pressure but most importantly rescued endothelial-dependent relaxation, normalized mitochondrial O 2 . - and restored endothelial nitric oxide. Second, we tested if pharmacological induction of Sirt3 by hexafluoro (i.p. 8 mg/kg, 4 days) after onset of angiotensin II-induced hypertension improves endothelial function and reduces hypertension. It was found that hexafluoro substantially reduced systolic blood pressure, significantly diminished vascular mitochondrial O 2 . - and improved endothelial nitric oxide. To test the role of endothelial Sirt3 in pharmacological effect of hexafluoro we used endothelial specific Sirt3 knockout mice and angiotensin II model of hypertension. Interestingly, hexafluoro was not effective in endothelial Sirt3 deficient mice supporting specific role of endothelial Sirt3. These studies demonstrate therapeutic potential of genetic and pharmacological endothelial Sirt3 induction after onset of hypertension for treatment of endothelial dysfunction diminishing cardiovascular disease.

Abstract 15464: Mitochondrial Function of Adventitial Fibroblasts in Pulmonary Hypertension is Regulated Through Sirt3 Deacetylase Activity

Introduction: Pulmonary hypertension (PH) is a heterogeneous and life-threatening cardiopulmonary disorder in which mitochondrial dysfunction drive pathogenesis. Although metabolic changes in PH draw attention of extensive investigation, the underlying mechanisms remain unclear. Hypothesis: Decreased Sirt3 mitochondrial deacetylase activity leads to increased mitochondrial enzyme acetylation level and mitochondrial dysfunction in pulmonary artery adventitial fibroblast cells isolated from IPAH patients (PH-Fibs). Methods: 1) qPCR and western blot to examine Sirt3 gene and protein levels in PH-Fibs and CO-Fibs, 2) western blotting of isolated mitochondrial protein acetylation level to examine the Sirt3 deacetylase activity, 3) immunostaining of mitochondrial SOD2 (direct target of Sirt3) acetylation level in lung tissues from PAH patients to examine Sirt3 deacetylase activity in vivo, 4) respiratory analysis and fluorescent lifetime imaging microscopy (FLIM) to analyze the glycolytic and mitochondrial function in cells, 5) overexpressing Sirt3 and supplement NAD + to investigate the therapeutic potential of regulating mitochondrial enzyme acetylation level and mitochondrial function in PH-Fibs. Results: PH-Fibs have decreased Sirt3 mRNA and protein levels compared to CO-Fibs. NAD + , a Sirt3 co-factor, is also decreased in PH-Fibs. Increased mitochondrial protein pan-acetylation levels and mitochondrial specific Sirt3 target (MnSOD2) were identified in cultured PH-Fibs, as well as lung vasculatures of IPAH patients, indicating the decreased mitochondrial deacetylase activity of Sirt3 in vitro and in vivo. We demonstrated increased glycolytic capacity and impaired mitochondrial function in PH-Fibs compared to CO-Fibs. Finally, by overexpressing Sirt3 level and at the same time increase NAD + availability, we proved that Sirt3 and NAD + can serve as therapeutic methods to synergistically improve mitochondrial function by regulating mitochondrial enzyme acetylation level in PH-Fibs. Conclusions: This study demonstrated that the mitochondrial deacetylase activity of Sirt3 as a critical mechanism regulating mitochondrial protein acetylation and mitochondrial function of fibroblast cells in IPAH patients.

Abstract 046: Induction Of Endothelial Sirt3 After Onset Of Hypertension Rescues Endothelial Function

Endothelial dysfunction plays a key role in the pathogenesis of hypertension and represents a major risk factor for cardiovascular disease. Despite treatment with multiple drugs, only 1 in 4 patients has blood pressure under control. We discovered a new synergistic control point with the potential to address this problem. We have shown that Sirt3 level is reduced in essential hypertension and endothelial Sirt3 overexpression attenuates endothelial dysfunction and hypertension. We proposed that induction endothelial Sirt3 after onset of hypertension rescues endothelial function and reduces hypertension. To test this hypothesis, we used genetic- and pharmacological Sirt3 induction. To genetically induce the expression of endothelial Sirt3 we used Sirt3 flox/flox mice crossed with VeCad-Cre mice treated with low dose of 4-hydroxytamoxifen (4HOT, i.p. 0.3 mg/20 g daily, 5 days) which does not have off-target cardiovascular effects. Mice underwent telemetry placement and ten days later received 4-week osmotic pumps containing vehicle (saline) or angiotensin II (0.7 mg/kg/day). 14-days later half of mice received 4HOT to induce endothelial Sirt3 overexpression. Treatment of mice with 4HOT after onset of hypertension slightly reduced blood pressure but most importantly completely rescued endothelial-dependent relaxation, normalized mitochondrial O 2 . - and restored endothelial nitric oxide. Second, we tested if pharmacological induction of Sirt3 by hexafluoro (i.p. 8 mg/kg, 4 days) after onset of angiotensin II-induced hypertension improves endothelial function and reduces hypertension. It was found that hexafluoro substantially reduced systolic blood pressure, significantly diminished vascular mitochondrial O 2 . - and improved endothelial nitric oxide. To test the role of endothelial Sirt3 in pharmacological effect of hexafluoro we used endothelial specific Sirt3 knockout mice and angiotensin II model of hypertension. Interestingly, hexafluoro was not effective in endothelial Sirt3 deficient mice supporting critical role of endothelial Sirt3. These in vivo studies demonstrate therapeutic potential of genetic and pharmacological endothelial Sirt3 induction after onset of hypertension for treatment of endothelial dysfunction.

Abstract 33: Impaired Mitochondrial Metabolism Contributes To Endothelial Dysfunction And Hypertension Independently From Oxidative Stress

Metabolic disorders contribute to pathogenesis of endothelial dysfunction, and mitochondrial deacetylase Sirt3 is critical in regulation of metabolic and antioxidant functions, but the role of Sirt3 has been largely ignored. We have recently shown that Sirt3 level is reduced in human hypertension. We propose Sirt3 as a novel target to improve the treatment of endothelial dysfunction and hypertension. Oxidative stress promotes metabolic dysregulation while metabolic conditions increase production of reactive oxygen species. In this work we have discerned the pathological role of impaired mitochondrial metabolism and oxidative stress using our new SOD2K68R deacetylation mimic mouse model. SOD2K68R mice are protected from oxidative stress because mutation of lysine 68 to arginine prevents SOD2 inactivation by acetylation. To define the specific role of impaired mitochondrial metabolism in endothelial dysfunction and hypertension, we have crossed SOD2K68R with Sirt3 -/- mice. Resultant SOD2K68R-Sirt3 -/- mice are protected from mitochondrial oxidative stress but have impaired Sirt3-mediated mitochondrial metabolism. We have tested the hypothesis that impaired Sirt3-mediated mitochondrial metabolism in SOD2K68R-Sirt3 -/- mice promotes vascular dysfunction and hypertension. SOD2K68R-Sirt3 -/- mice are protected from AngII-induced superoxide measured by mitoSOX and DHE. Meanwhile, systolic blood pressure in AngII-infused SOD2K68R-Sirt3 -/- mice was substantially higher than in SOD2K68R mice but lower than in Sirt3 -/- mice. To define the role of mitochondrial metabolism in vascular homeostasis we analyzed metabolic, inflammatory, and cellular pathways. LCAD hyperacetylation and increased HIF1α in SOD2K68R-Sirt3 -/- mice indicates impaired mitochondrial fatty acid oxidation and increased glycolysis which were further exacerbated by AngII-infusion and NFkB/ICAM increase promoting vascular inflammation. The loss of VeCAD in SOD2K68R-Sirt3 -/- Sham mice was further aggravated in AngII-infusion supporting alteration of endothelial phenotype in SOD2K68R-Sirt3 -/- mice. These data indicate that impaired mitochondrial metabolism contributes to endothelial dysfunction and hypertension independently from oxidative stress.

Serum levels of SIRT3 and other inflammatory factors are associated with clinical outcomes and prognosis in severe community-acquired pneumonia in adults: A prospective study.

The aim of this study was to investigate clinical significance of SIRT3 in severe community-acquired pneumonia (CAP) patients.This prospective observational research enrolled a total of 114 severe CAP patients who went to our hospital during January 2018 to December 2019. Serum SIRT3 and IL-1β, IL-6, and tumor necrosis factor (TNF)-α levels were determined using the enzyme-linked immunosorbent assay (ELISA) method. Demographic data, including age, sex, and body mass index (BMI), as well as clinical symptoms, SOFA and SMART-COP scores were collected. The routine blood test was conducted for all patients and white blood cell (WBC) amount, as well as serum levels of C-reactive protein (CRP), D-Dimer, and procalcitonin (PCT).Among all patients, 55 cases died during the study period. The serum levels of CRP, PCT, IL-1β, and IL-6, as well as SOFA and SMART-COP scores were markedly higher in deceased patients than in the survival patients. The expression of SIRT3 was significantly decreased in severe CAP patients compared with the healthy, especially in the deceased patients. SIRT3 levels were negatively correlated with levels of CRP, PCT, IL-1β, and IL-6. Patients with SIRT3 low expression showed remarkably higher expression of CRP, PCT, IL-1β, and IL-6, as well as high SMART-COP scores, higher 1-month mortality rate, and shorter survival. Only SIRT3 and IL-1β were independent risk factors for 1-month mortality in severe CAP patients.Lower serum SIRT3 level predicts poor clinical outcomes and prognosis in severe CAP patients.

Therapeutic effect of SIRT3 on glucocorticoid-induced osteonecrosis of the femoral head via intracellular oxidative suppression

Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) is a serious complication after long-term or excess administration of clinical glucocorticoids intervention, and the pathogenic mechanisms underlying have not been clarified yet. Oxidative stress is considered as a major cause of bone homeostasis disorder. This study is aimed to explore the potential relevance between SIRT3 and GIONFH, as well as the effect of resveratrol, which has been reported for its role in SIRT3 activation, on dexamethasone-induced oxidative stress and mitochondrial compromise in bone marrow stem cells (BMSCs). In this study, our data showed that SIRT3 level was declined in GIONFH rat femoral head, corresponding to a resultant decrease of SIRT3 expression in dexamethasone-treated BMSCs in vitro. We also found that dexamethasone could result in oxidative injury in BMSCs, and resveratrol treatment reduced this deleterious effect via a SIRT3-dependent manner. Moreover, our results demonstrated that rewarding effect of resveratrol on BMSCs osteogenic differentiation was via activation of AMPK/PGC-1α/SIRT3 axis. Meanwhile, resveratrol administration prevented the occurrence of GIONFH, enhanced SIRT3 expression and reduced oxidative level in GIONFH model rats. Therefore, our study provides basic evidence that SIRT3 may be a promising therapeutic target for GIONFH treatment and resveratrol could be an ideal agent for clinical uses.

Deletion of SIRT3 inhibits osteoclastogenesis and alleviates aging or estrogen deficiency-induced bone loss in female mice.

SIRT3 has been speculated to affect osteoclast activity through its important roles in regulating mitochondrial function. It remains unclear whether SIRT3 affects osteoclast activity in female mice which is relevant to postmenopausal osteoporosis. We hypothesized that deletion of SIRT3 could modulate bone remodeling in female mice under physiological aging process or ovariectomy (OVX)-induced bone loss. We found that SIRT3 level was markedly increased in primary bone marrow-derived macrophages (BMMs) from both 26-month-old aged mice and OVX mice. Knockdown of SIRT3 in vitro inhibited osteoclast differentiation and mitochondrial biogenesis, and deletion of SIRT3 increased trabecular bone mass in female mice due to impaired osteoclastogenesis. The effect of SIRT3 on bone remodeling appears to be age-dependent as revealed by comparing the effect of SIRT3 deletion on 5-week-old, 3-month-old and 6-month-old female mice. Interestingly, Sirt3-/- mice were more resistant to bone loss following estrogen deficiency resulting from OVX. Our findings demonstrated that SIRT3 could play critical roles in bone remodeling and estrogen deficiency-induced bone loss in female mice, suggesting that SIRT3 and its downstream effectors might be potential novel therapeutic targets for the management of postmenopausal osteoporosis.

Mitochondrial function in skeletal myofibers is controlled by a TRF2-SIRT3 axis over lifetime.

Telomere shortening follows a developmentally regulated process that leads to replicative senescence of dividing cells. However, whether telomere changes are involved in postmitotic cell function and aging remains elusive. In this study, we discovered that the level of the TRF2 protein, a key telomere‐capping protein, declines in human skeletal muscle over lifetime. In cultured human myotubes, TRF2 downregulation did not trigger telomere dysfunction, but suppressed expression of the mitochondrial Sirtuin 3 gene (SIRT3) leading to mitochondrial respiration dysfunction and increased levels of reactive oxygen species. Importantly, restoring the Sirt3 level in TRF2‐compromised myotubes fully rescued mitochondrial functions. Finally, targeted ablation of the Terf2 gene in mouse skeletal muscle leads to mitochondrial dysfunction and sirt3 downregulation similarly to those of TRF2‐compromised human myotubes. Altogether, these results reveal a TRF2‐SIRT3 axis controlling muscle mitochondrial function. We propose that this axis connects developmentally regulated telomere changes to muscle redox metabolism.

Activated PI3K/AKT Signaling Pathway Associates with Oxidative Stress and Impaired Developmental Potential of Vitrified-Thawed Oocytes.

It was suggested that the compromised developmental potential of vitrified-thawed oocytes was due to the oxidative stress occurred during the process. PI3K/AKT signaling pathway is important in response to stress. The present study aimed to investigate the role of PI3K/AKT played in oocyte vitrification and thawing. The results revealed that the fertilization rate, cleavage rate, as well as the blastocyst formation rate were significantly lower in the vitrified-thawed oocytes than that of the control counterparts [63.81 ± 7.19 vs. 82.00 ± 4.21% (P < 0.05), 58.89 ± 8.39 vs. 78.92 ± 2.78% (P < 0.05), and 59.37 ± 7.03 vs. 74.56 ± 5.06% (P < 0.05), respectively]. Significantly increased reactive oxygen species (ROS) level (P < 0.01), decreased mitochondrial membrane potential (P < 0.01), and declined SIRT3 expression level (P < 0.01) were observed in vitrified-thawed oocytes compared with that of the fresh group. In addition, enhanced PIK3CA was quantified (P < 0.05), and the protein expression levels of PIK3CA (P < 0.05) and P-AKT (P < 0.01) were increased in vitrified-thawed oocytes compared to the fresh ones. Also, decreased SIRT3 level was observed after vitrification/thawing (P < 0.01). In conclusion, our data demonstrated a link between activated PI3K/AKT signaling pathway in response to oxidative stress and compromised developmental potential in vitrified-thawed oocytes.

Role of AMPK/SIRT1-SIRT3 signaling pathway in affective disorders in unpredictable chronic mild stress mice

ObjectivesTo explore the role of 5′ adenosine monophosphate-activated protein kinase/sirtuin1-sirtuin3 (AMPK/SIRT1-SIRT3) signaling pathway in behavioral and neuroinflammation/oxidative stress alterations in unpredictable chronic mild stress (UCMS) model mice. MethodsMale ICR mice weighing 20–22 g were used in this study. Behavior performance was evaluated from the 14th day of drug treatment. Expression levels of AMPK, SIRT1, SIRT3, and NF-κBp65 were tested by immuno-blot analysis. Contents of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β) and interleukin 6 (IL-6) were detected by enzyme linked immunosorbent assay (ELISA). Reactive oxygen species (ROS), superoxide dismutase (SOD) and glutathione (GSH) expressions were tested by neurochemical and biochemical assays. ResultsBehavioral disorders and decreases of AMPK, SIRT1 and SIRT3 induced by UCMS were all reversed by AICA Riboside (AICAR) treatment. These effects were correlated with alterations of oxidative stress (ROS, GSH, SOD) and inflammation (pNF-κBp65, TNF-α, IL-1β, IL-6) status. Co-treatment with SIRT3 inhibitor (3-TYP) in addition to AICAR abolished AICAR's effects on behavior and expression level of inflammation/oxidative stress-related factors of mice, without affecting the content of SIRT1. Contrarily, combining use of AICAR and SIRT1 inhibitor (Sirtinol or EX-527) increased SIRT3 level, which led to better alleviation of behavioral disorders, compared with single AICAR treatment. Interestingly, in normal or UCMS mice, up or down regulation of SIRT1 did not affect SIRT3 level. ConclusionProvided that AMPK is activated, SIRT1 inhibition could induce the increase of SIRT3, and SIRT3 exerts more beneficial function in alleviation of consequences of chronic stress than SIRT1.

Mitochondrial Deacetylase Sirt3 Reduces Vascular Dysfunction and Hypertension While Sirt3 Depletion in Essential Hypertension Is Linked to Vascular Inflammation and Oxidative Stress.

Hypertension represents a major risk factor for stroke, myocardial infarction, and heart failure and affects 30% of the adult population. Mitochondrial dysfunction contributes to hypertension, but specific mechanisms are unclear. The mitochondrial deacetylase Sirt3 (Sirtuin 3) is critical in the regulation of metabolic and antioxidant functions which are associated with hypertension, and cardiovascular disease risk factors diminish Sirt3 level. We hypothesized that reduced Sirt3 expression contributes to vascular dysfunction in hypertension, but increased Sirt3 protects vascular function and decreases hypertension. To test the therapeutic potential of targeting Sirt3 expression, we developed new transgenic mice with global Sirt3OX (Sirt3 overexpression), which protects from endothelial dysfunction, vascular oxidative stress, and hypertrophy and attenuates Ang II (angiotensin II) and deoxycorticosterone acetate-salt induced hypertension. Global Sirt3 depletion in Sirt3-/- mice results in oxidative stress due to hyperacetylation of mitochondrial superoxide dismutase (SOD2), increases HIF1α (hypoxia-inducible factor-1), reduces endothelial cadherin, stimulates vascular hypertrophy, increases vascular permeability and vascular inflammation (p65, caspase 1, VCAM [vascular cell adhesion molecule-1], ICAM [intercellular adhesion molecule-1], and MCP1 [monocyte chemoattractant protein 1]), increases inflammatory cell infiltration in the kidney, reduces telomerase expression, and accelerates vascular senescence and age-dependent hypertension; conversely, increased Sirt3 expression in Sirt3OX mice prevents these deleterious effects. The clinical relevance of Sirt3 depletion was confirmed in arterioles from human mediastinal fat in patients with essential hypertension showing a 40% decrease in vascular Sirt3, coupled with Sirt3-dependent 3-fold increases in SOD2 acetylation, NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activity, VCAM, ICAM, and MCP1 levels in hypertensive subjects compared with normotensive subjects. We suggest that Sirt3 depletion in hypertension promotes endothelial dysfunction, vascular hypertrophy, vascular inflammation, and end-organ damage. Our data support a therapeutic potential of targeting Sirt3 expression in vascular dysfunction and hypertension.

Abstract P3018: Sirt3 Depletion in Human Essential Hypertension is Linked to Vascular Inflammation and Oxidative Stress While Endothelial Specific Sirt3 Depletion in Mice Promotes Vascular Dysfunction and Increases Hypertension

Hypertension represents a major risk factor for stroke, myocardial infarction, and heart failure and affects 30% of adult population. Vascular dysfunction is crucial in hypertension pathophysiology and exhibits bidirectional relationship. Metabolic disorders and oxidative stress contribute to vascular dysfunction, and mitochondrial deacetylase Sirt3 is critical in the regulation of metabolic and antioxidant functions. We hypothesized that reduced Sirt3 expression contributes to vascular dysfunction and essential hypertension. We studied Sirt3 in arterioles from human mediastinal fat in patients with essential hypertension compared with normotensive subjects. Pathophysiological role of vascular Sirt3 depletion was studied in mice with tamoxifen-inducible endothelial specific Sirt3 depletion (Ec Sirt3KO ). For the first time, we showed a 40% decrease in vascular Sirt3 level and 400% increase in SOD2 acetylation in hypertensive subjects which was linked to increased oxidative stress measured by superoxide overproduction and vascular inflammation due to elevated NfKB activity, VCAM, ICAM and MCP-1 levels. Interestingly, global Sirt3 depletion in mice increases blood pressure, inactivates key mitochondrial antioxidant SOD2 due to acetylation, increases vascular p65, VCAM, ICAM and MCP1, and increased T cell infiltration in kidney, induces cell-senescence and promotes vascular aging while global Sirt3 overexpression prevents these deleterious effects. We tested if Ec Sirt3KO mice have vascular dysfunction and hypertension. Both basal and angiotensin II-induced blood pressure was increased in Ec Sirt3KO mice accompanied by endothelial dysfunction and vascular O 2 • overproduction. Treatment of Ec Sirt3KO mice with SOD2-mimetic mitoTEMPO reduced vascular inflammation, markers of cell-senescence and vascular aging to the wild-type control levels while treatment of Ang II-infused Ec Sirt3KO mice partially rescues from vascular inflammation and attenuates accelerated vascular aging. We suggest that Sirt3 depletion in hypertension promotes both endothelial oxidative stress and metabolic dysfunction. Our data support a therapeutic potential of targeting Sirt3 expression in vascular dysfunction and hypertension.

Crosstalk Between Mitochondrial Hyperacetylation and Oxidative Stress in Vascular Dysfunction and Hypertension.

Significance: Vascular dysfunction plays a key role in the development of arteriosclerosis, heart disease, and hypertension, which causes one-third of deaths worldwide. Vascular oxidative stress and metabolic disorders contribute to vascular dysfunction, leading to impaired vasorelaxation, vascular hypertrophy, fibrosis, and aortic stiffening. Mitochondria are critical in the regulation of metabolic and antioxidant functions; therefore, mitochondria-targeted treatments could be beneficial. Recent Advances: Vascular dysfunction is crucial in hypertension pathophysiology and exhibits bidirectional relationship. Metabolic disorders and oxidative stress contribute to the pathogenesis of vascular dysfunction and hypertension, which are associated with mitochondrial impairment and hyperacetylation. Mitochondrial deacetylase Sirtuin 3 (Sirt3) is critical in the regulation of metabolic and antioxidant functions. Clinical studies show that cardiovascular disease risk factors reduce Sirt3 level and Sirt3 declines with age, paralleling the increased incidence of cardiovascular disease and hypertension. An imbalance between mitochondrial acetylation and reduced Sirt3 activity contributes to mitochondrial dysfunction and oxidative stress. We propose that mitochondrial hyperacetylation drives a vicious cycle between metabolic disorders and mitochondrial oxidative stress, promoting vascular dysfunction and hypertension. Critical Issues: The mechanisms of mitochondrial dysfunction are still obscure in human hypertension. Mitochondrial hyperacetylation and oxidative stress contribute to mitochondrial dysfunction; however, regulation of mitochondrial acetylation, the role of GCN5L1 (acetyl-CoA-binding protein promoting acetyltransferase protein acetylation) acetyltransferase, Sirt3 deacetylase, and acetylation of specific proteins require further investigations. Future Directions: There is an urgent need to define molecular mechanisms and the pathophysiological role of mitochondrial hyperacetylation, identify novel pharmacological targets, and develop therapeutic approaches to reduce this phenomenon.

Abstract 16961: KLF15 Regulates the Circadian Susceptibility to Ischemia Reperfusion Injury in the Heart

The onset and the injury of heart attacks show a circadian rhythmicity with a peak during the sleep to active transition. Studies using cell type specific clock mutant demonstrated the intrinsic varying susceptibility of the cardiomyocytes to the ischemia reperfusion (I/R) injury, however, the molecular mechanisms remain unclear. Recently, we show that transcription factor KLF15 coordinates the diurnal expression of catabolic genes in the heart during the active phase. Here we show that cardiomyocyte specific KLF15 deficient mice have exaggerated I/R injury in vivo during the sleep to active transition but not the active to sleep transition, demonstrating its critical role in governing the circadian rhythmicity of myocardial injury. We found acute KLF15 deficiency in the primary cardiomyocytes is associated with increased ROS and exaggerated susceptibility to oxidative stress, which can be rescued by a MnSOD mimetic Tempol. We further demonstrate that KLF15 deficiency in the cardiomyocytes in vitro and in vivo are both associated with increased acetylation of MnSOD K122 , which leads to reduced MnSOD activity. There is no change in mitochondrial sirtuin SIRT3 level, the main deacetylase for MnSOD K122 , however its co-enzyme NAD + level and NAD + /NADH ratio are drastically reduced with KLF15 deficiency. We show that NAD + precursor NMN rescues the increased susceptibility to ROS in KLF15 deficient cardiomyocytes in vitro in a SIRT3 dependent fashion and rescues the increased cardiac I/R injury of KLF15 deficient mice specifically at ZT14. We show that KLF15 directly regulates nicotinamide phosphoribosyltransferase (NAMPT), the rate limiting enzyme of NAD + salvage pathway and the NAD + determinant in the heart. We found a strong circadian rhythmicity of NAD + level and mitochondrial acetylation in the heart. The beginning of the active phase is associated with increased expression of KLF15, NAMPT, NAD + , and reduced acetylation at MnSOD K122 . Collectively, our results demonstrate that KLF15 coordinates cardiac metabolism and ROS clearance in a circadian fashion through mitochondrial NAD + ; loss of KLF15 expression in ischemic cardiomyopathy likely contributes to an enhanced susceptibility to additional I/R insult in a time-of-the-day dependent fashion.

SirT3 regulates diabetogenic effects caused by arsenic: An implication for mitochondrial complex II modification

BackgroundA large body of evidence indicates that accumulation of oxidative stress originated from impaired mitochondrial respiratory chain is the main cause for the development of numerous diseases including diabetes and cancer. Arsenic exposure is a potential risk factor for type 2 diabetes development which, by disrupting mitochondrial respiration and SirT3 enzyme activity, enhances reactive oxygen species (ROS) level and evokes oxidative stress. In this study the impact of arsenic exposure on the mitochondrial function and SirT3 from rat's liver were examined in the presence or absence of metformin and berberine. MethodsSerum glucose and insulin levels were assessed in rats exposed to the diabetogenic concentration of arsenic. Isolated hepatocytes and mitochondria were then further evaluated to determine any deleterious consequences. ResultsDiabetogenesis triggered by arsenic contributed to the mitochondrial ROS overproduction, impaired complex II activity, glucose homeostasis, glucose tolerance and insulin sensitivity. An increased SirT3 level indicated the compensatory mechanism to deal with this condition. Protective effect of metformin and berberine against these toxic insults were found to be associated with the mitochondrial SirT3 pathway. This pathway through the regulation of mitochondria-associated ROS production and glucose homeostasis in the liver may play a crucial role against the diabetogenic effect of arsenic.