Berberine ameliorates chronic intermittent hypoxia-induced cardiac remodelling by preserving mitochondrial function, role of SIRT6 signalling.

Chronic intermittent hypoxia (CIH) is associated with an increased risk of cardiovascular diseases. Previously, we have shown that berberine (BBR) is a potential cardioprotective agent. However, its effect and mechanism on CIH-induced cardiomyopathy remain uncovered. This study was designed to determine the effects of BBR against CIH-induced cardiac damage and to explore the molecular mechanisms. Mice were exposed to 5 weeks of CIH with or without the treatment of BBR and adeno-associated virus 9 (AAV9) carrying SIRT6 or SIRT6-specific short hairpin RNA. The effect of BBR was evaluated by echocardiography, histological analysis and western blot analysis. CIH caused the inactivation of myocardial SIRT6 and AMPK-FOXO3a signalling. BBR dose-dependently ameliorated cardiac injury in CIH-induced mice, as evidenced by increased cardiac function and decreased fibrosis. Notably, SIRT6 overexpression mimicked these beneficial effects, whereas infection with recombinant AAV9 carrying SIRT6-specific short hairpin RNA abrogated them. Mechanistically, BBR reduced oxidative stress damage and preserved mitochondrial function via activating SIRT6-AMPK-FOXO3a signalling, enhancing mitochondrial biogenesis as well as PINK1-Parkin-mediated mitophagy. Taken together, these data demonstrate that SIRT6 activation protects against the pathogenesis of CIH-induced cardiac dysfunction. BBR attenuates CIH-induced myocardial injury by improving mitochondrial biogenesis and PINK1-Parkin-dependent mitophagy via the SIRT6-AMPK-FOXO3a signalling pathway.

Inhibition of ferroptosis by icariin treatment attenuates excessive ethanol consumption-induced atrial remodeling and susceptibility to atrial fibrillation, role of SIRT1.

Ferroptosis contributes to the pathogenesis of atrial fibrillation (AF), although the mechanisms are still largely uncovered. The current study was designed to explore the pharmacological effects of icariin against ethanol-induced atrial remodeling, if any, and the mechanisms involved with a focus on SIRT1 signaling. Excessive ethanol-treated animals were administered with Ferrostatin-1, Erastin or icariin to evaluate the potential effects of icariin or ferroptosis. Then, the underling mechanisms was further explored in the in vitro experiments using HL-1 atrial myocytes. Excessive ethanol administration caused significant atrial damage as evidenced by increased susceptibility to AF, altered atrial conduction pattern, atrial enlargement, and enhanced fibrotic markers. These detrimental effects were reversed by Ferrostatin-1 or icariin treatment, while Erastin co-administration markedly abolished the beneficial actions conferred by icariin. Mechanistically, ethanol-treated atria exhibited markedly up-regulated pro-ferroptotic protein (PTGS2, ACSL4, P53) and suppressed anti-ferroptotic molecules (GPX4, FTH1). Icariin treatment inhibited ethanol-induced atrial ferroptosis by reducing atrial mitochondrial damage, ROS accumulation and iron overload. Interestingly, the in vivo and in vitro data showed that icariin activated atrial SIRT1-Nrf-2-HO-1 signaling pathway, while EX527 not only reversed these effects, but also abolished the therapeutic effects of icariin. Moreover, the stimulatory effects on GPX4, SLC7A11 and the suppressive effects on ACSL4, P53 conferred by icariin were blunted by EX527 treatment. These data demonstrate that ferroptosis plays a causative role in the pathogenesis of ethanol-induced atrial remodeling and susceptibility to AF. Icariin protects against atrial damage by inhibiting ferroptosis via SIRT1 signaling. Its role as a prophylactic/therapeutic drug deserves further clinical study.

Palmitic acid induces GSDMD-mediated pyroptosis in periodontal ligament cells via the NF-κB pathway.

OBJECTIVE: Obesity can affect periodontal tissues and exacerbate periodontitis. Pyroptosis, a newly identified type of inflammatory cell death, is involved in the development of periodontal inflammation. The saturated fatty acid palmitic acid (PA) is elevated in obese patients. The effect of PA on pyroptosis in periodontal ligament cells (PDLCs) and its underlying mechanisms remain unknown. MATERIALS AND METHODS: Human PDLCs were isolated from healthy individuals and cultured for experiments. The effects of PA on PDLC pyroptosis and the underlying mechanisms were examined by transmission electron microscopy, quantitative real-time PCR and western blotting. RESULTS: The morphology of PDLCs in the PA group indicated pyroptotic characteristics, including swollen cells, plasma membrane rupture and changes in subcellular organelles. PA induced inflammatory responses in PDLCs, as indicated by an increase in IL-1ß in the cell culture supernatant. Furthermore, we found that the pyroptosis-related proteins caspase-1, caspase-4 and GSDMD were involved in PA-induced cell death. GSDMD and caspase-4 inhibitors alleviated pyroptotic death of PDLCs. Moreover, PA promoted NF-κB P65 phosphorylation. A NF-κB inhibitor decreased IL-1ß expression and partly rescued cell death induced by PA. CONCLUSION: PA activated the NF-κB pathway and induced the inflammatory response in PDLCs. Caspase-4/GSDMD mediated PDLC pyroptosis induced by PA.

Pediatric sleep-disordered breathing in Shanghai: characteristics, independent risk factors and its association with malocclusion.

OBJECTIVES: This study aimed to determine the prevalence and independent risk factors of SDB, and explore its association with malocclusion among 6-11-year-old children in Shanghai, China. METHODS: A cluster sampling procedure was adopted in this cross-sectional study. Pediatric Sleep Questionnaire (PSQ) was applied to evaluate the presence of SDB. Questionnaires including PSQ, medical history, family history, and daily habits/environment were completed by parents under instruction, and oral examinations were implemented by well-trained orthodontists. Multivariable logistic regression was applied to identify independent risk factors for SDB. Chi-square tests and Spearman's Rank Correlation were used to estimate the relationship between SDB and malocclusion. RESULTS: A total of 3433 subjects (1788 males and 1645 females) were included in the study. The SDB prevalence was about 17.7%. Allergic rhinitis (OR 1.39, 95% CI 1.09-1.79), adenotonsillar hypertrophy (OR 2.39, 95% CI 1.82-3.19), paternal snoring (OR 1.97, 95% CI 1.53-2.53), and maternal snoring (OR 1.35, 95% CI 1.05-1.73) were independent risk factors for SDB. The SDB prevalence was higher in children with retrusive mandibles than in proper or excessive ones. No significant difference was observed in the correlation between SDB and lateral facial profile, mandible plane angle, constricted dental arch form, the severity of anterior overjet and overbite, degree of crowding and spacing, and the presence of crossbite and open bite. CONCLUSIONS: The prevalence of SDB in primary students in the Chinese urban population was high and highly associated with mandible retrusion. The independent risk factors included Allergic rhinitis, adenotonsillar hypertrophy, paternal snoring, and maternal snoring. More efforts should be made to enhance public education about SDB and related dental-maxillofacial abnormalities.

Advances in Molecular Pathology of Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is a common syndrome that features a complex etiology and set of mechanisms. Here we summarized the molecular pathogenesis of OSA, especially the prospective mechanism of upper? airway dilator fatigue and the current breakthroughs. Additionally, we also introduced the molecular mechanism of OSA in terms of related studies on the main signaling pathways and epigenetics alterations, such as microRNA, long non-coding RNA, and DNA methylation. We also reviewed small molecular compounds, which are potential targets for gene regulations in the future, that are involved in the regulation of OSA. This review will be beneficial to point the way for OSA research within the next decade.

Novel Functions of Endothelial Scavenger Receptor Class B Type I.

PURPOSE OF REVIEW: Scavenger receptor class B type I (SR-BI) serves a key role in the reverse cholesterol transport in the liver as the high-affinity receptor for HDL. SR-BI is abundantly expressed in endothelium, and earlier works indicate that the receptor mediates anti-atherogenic actions of HDL. However, more recent studies uncovered novel functions of endothelial SR-BI as a lipoprotein transporter, which regulates transcellular transport process of both LDL and HDL. This brief review focuses on the unique functions of endothelial SR-BI and how they influence atherogenesis. RECENT FINDINGS: Earlier studies indicate that SR-BI facilitates anti-atherogenic actions of HDL through modulation of intracellular signaling to stimulate endothelial nitric oxide synthase. In vivo studies in global SR-BI knockout mice also showed a strong atheroprotective role of the receptor; however, a contribution of endothelial SR-BI to atherosclerosis process in vivo has not been fully appreciated. Recent studies using cultured endothelial cells and in mice with endothelial-specific deletion of the receptor revealed previously unappreciated pro-atherogenic actions of SR-BI, which relates to its ability to deliver LDL into arteries. On the other hand, SR-BI has also been implicated in transport of HDL to the sub-intimal space as a part of reverse cholesterol transport. SR-BI mediates internalization and transcellular transport of both HDL and LDL, and the cellular and molecular mechanism of the process has just begun to emerge. Harnessing these dual transport functions of the endothelial SR-BI may provide a novel, effective intervention to atherosclerosis.

Melatonin attenuates diabetic cardiomyopathy and reduces myocardial vulnerability to ischemia-reperfusion injury by improving mitochondrial quality control: Role of SIRT6.

Targeting mitochondrial quality control with melatonin has been found promising for attenuating diabetic cardiomyopathy (DCM), although the underlying mechanisms remain largely undefined. Activation of SIRT6 and melatonin membrane receptors exerts cardioprotective effects while little is known about their roles during DCM. Using high-fat diet-streptozotocin-induced diabetic rat model, we found that prolonged diabetes significantly decreased nocturnal circulatory melatonin and heart melatonin levels, reduced the expressions of cardiac melatonin membrane receptors, and decreased myocardial SIRT6 and AMPK-PGC-1α-AKT signaling. 16 weeks of melatonin treatment inhibited the progression of DCM and the following myocardial ischemia-reperfusion (MI/R) injury by reducing mitochondrial fission, enhancing mitochondrial biogenesis and mitophagy via re-activating SIRT6 and AMPK-PGC-1α-AKT signaling. After the induction of diabetes, adeno-associated virus carrying SIRT6-specific small hairpin RNA or luzindole was delivered to the animals. We showed that SIRT6 knockdown or antagonizing melatonin receptors abolished the protective effects of melatonin against mitochondrial dysfunction as evidenced by aggravated mitochondrial fission and reduced mitochondrial biogenesis and mitophagy. Additionally, SIRT6 shRNA or luzindole inhibited melatonin-induced AMPK-PGC-1α-AKT activation as well as its cardioprotective actions. Collectively, we demonstrated that long-term melatonin treatment attenuated the progression of DCM and reduced myocardial vulnerability to MI/R injury through preserving mitochondrial quality control. Melatonin membrane receptor-mediated SIRT6-AMPK-PGC-1α-AKT axis played a key role in this process. Targeting SIRT6 with melatonin treatment may be a promising strategy for attenuating DCM and reducing myocardial vulnerability to ischemia-reperfusion injury in diabetic patients.

Simultaneous adsorption and determination of bisphenol compounds in water medium with a Zr(IV)-based metal-organic framework.

A chemically stable Zr(IV)-based metal-organic framework (BUT-17) has been explored for simultaneous adsorption and determination of bisphenol compounds (BPs) in aqueous medium. The prepared BUT-17 possesses a large surface area (2936 m2 g-1) and excellent fluorescent performance. An adsorption capacity of 111 mg g-1 for bisphenol A (BPA) with a rapid adsorption rate (1.76 g mg-1 min-1) is achieved by BUT-17. The excellent adsorption performance could be attributed to the hydrogen bond interaction between BPs and BUT-17. Furthermore, the fluorescent intensity of BUT-17 was quenched up to 92% due to the formation of complexes between BPs and BUT-17. Thus, a BUT-17-based fluorescent sensing method for the rapid determination of BPs has been established with the limit of detection of 10.0 ng mL-1 for BPA and a linear range from 2.0 to 23.0 µg mL-1. These results indicate that as an outstanding multifunctional platform, BUT-17 is promising for the simultaneous removal and determination of BPs in water medium. Simultaneous removal and detection of BPs with BUT-17.

Megakaryocytic Leukemia 1 Bridges Epigenetic Activation of NADPH Oxidase in Macrophages to Cardiac Ischemia-Reperfusion Injury.

BACKGROUND: Excessive accumulation of reactive oxygen species (ROS), catalyzed by the NADPH oxidases (NOX), is involved in the pathogenesis of ischemia-reperfusion (IR) injury. The underlying epigenetic mechanism remains elusive. METHODS: We evaluated the potential role of megakaryocytic leukemia 1 (MKL1), as a bridge linking epigenetic activation of NOX to ROS production and cardiac ischemia-reperfusion injury. RESULTS: Following IR injury, MKL1-deficient (knockout) mice exhibited smaller myocardial infarction along with improved heart function compared with wild-type littermates. Similarly, pharmaceutical inhibition of MKL1 with CCG-1423 also attenuated myocardial infarction and improved heart function in mice. Amelioration of IR injury as a result of MKL1 deletion or inhibition was accompanied by reduced ROS in vivo and in vitro. In response to IR, MKL1 levels were specifically elevated in macrophages, but not in cardiomyocytes, in the heart. Of note, macrophage-specific deletion (MϕcKO), instead of cardiomyocyte-restricted ablation (CMcKO), of MKL1 in mice led to similar improvements of infarct size, heart function, and myocardial ROS generation. Reporter assay and chromatin immunoprecipitation assay revealed that MKL1 directly bound to the promoters of NOX genes to activate NOX transcription. Mechanistically, MKL1 recruited the histone acetyltransferase MOF (male absent on the first) to modify the chromatin structure surrounding the NOX promoters. Knockdown of MOF in macrophages blocked hypoxia/reoxygenation-induced NOX transactivation and ROS accumulation. Of importance, pharmaceutical inhibition of MOF with MG149 significantly downregulated NOX1/NOX4 expression, dampened ROS production, and normalized myocardial function in mice exposed to IR injury. Finally, administration of a specific NOX1/4 inhibitor GKT137831 dampened ROS generation and rescued heart function after IR in mice. CONCLUSIONS: Our data delineate an MKL1-MOF-NOX axis in macrophages that contributes to IR injury, and as such we have provided novel therapeutic targets in the treatment of ischemic heart disease.

Investigating the repair of alveolar bone defects by gelatin methacrylate hydrogels-encapsulated human periodontal ligament stem cells.

Although various efforts have been made to develop effective treatments for alveolar bone defect, alveolar regeneration has been emerging as the one with the most potential Herein, we investigated the potential of gelatin methacrylate (GelMA) hydrogels-encapsulated human periodontal ligament stem cells (hPDLSCs) to regenerate alveolar bone. The easy, rapid, and cost-effective nature of GelMA hydrogels makes them a promising mode of stem cell-delivery for clinically relevant alveolar bone regeneration. More importantly, GelMA hydrogels provide an optimal niche for hPDLSCs proliferation, migration and osteogenic differentiation, which are critical for alveolar bone regeneration. In this study, we examined the microstructure of GelMA hydrogels, and identified a highly porous and interconnected network. Compressive test of GelMA hydrogels showed that the stress reached a maximum value of 13.67 ± 0.03 kPa when the strain reached 55%. The maximum values of swelling ratio were 700 ± 47% at the fifth hour. The proliferation rate of hPDLSCs in the GelMA hydrogels resembled that in 2D culture and gradually increased. We established a critical-sized rat model of alveolar bone defects, and applied Micro-CT to assess new bone formation. Compared to the control group, there was substantial bone regeneration in the GelMA + hPDLSCs group at both 4 and 8 weeks after the operation. Histological analysis results were consistent with Micro-CT results. Our study demonstrates that the GelMA hydrogels-encapsulated hPDLSCs have a significant alveolar regenerative potential, and may represent a new strategy for the therapy of alveolar bone defects.

Brg1 trans-activates endothelium-derived colony stimulating factor to promote calcium chloride induced abdominal aortic aneurysm in mice.

Endothelial cell derived secretive factors play pivotal roles maintaining the homeostasis by influencing the behaviors of other cells. When dysregulated, these factors may contribute to the disruption of physiological integrity and promote disease genesis in a number of different tissues and organs. In the present study we investigated how targeted deletion of brahma related gene 1 (Brg1), a chromatin remodeling protein, in endothelium might affect the pathogenesis of abdominal aortic aneurysm (AAA) induced by calcium chloride (CaCl2). We report here that compared to the wild type (WT) littermates, endothelial conditional Brg1 knockout (ecKO) mice exhibited an attenuated phenotype of AAA. Immunostaining and quantitative PCR analyses showed that vascular inflammation was suppressed in ecKO mice as opposed to WT mice likely due to diminished recruitment of macrophages. Further examination revealed that Brg1 deficiency led to a reduction in colony stimulating factor 1 (CSF1) levels. In cultured endothelial cells, Brg1 cooperated with histone H3K9 demethylase KDM3A to activate CSF1 transcription and macrophage recruitment thereby perpetuating vascular inflammation. Depletion of BRG1 or KDM3A in endothelial cells dampened CSF1 production and attenuated macrophage chemotaxis. Therefore, our data suggest that epigenetic activation of CSF1 transcription by Brg1 may contribute to AAA pathogenesis.

Melatonin protects diabetic heart against ischemia-reperfusion injury, role of membrane receptor-dependent cGMP-PKG activation.

It has been demonstrated that the anti-oxidative and cardioprotective effects of melatonin are, at least in part, mediated by its membrane receptors. However, the direct downstream signaling remains unknown. We previously found that melatonin ameliorated myocardial ischemia-reperfusion (MI/R) injury in diabetic animals, although the underlying mechanisms are also incompletely understood. This study was designed to determine the role of melatonin membrane receptors in melatonin's cardioprotective actions against diabetic MI/R injury with a focus on cGMP and its downstream effector PKG. Streptozotocin-induced diabetic Sprague-Dawley rats and high-glucose medium-incubated H9c2 cardiomyoblasts were utilized to determine the effects of melatonin against MI/R injury. Melatonin treatment preserved cardiac function and reduced oxidative damage and apoptosis. Additionally, melatonin increased intracellular cGMP level, PKGIα expression, p-VASP/VASP ratio and further modulated myocardial Nrf-2-HO-1 and MAPK signaling. However, these effects were blunted by KT5823 (a selective inhibitor of PKG) or PKGIα siRNA except that intracellular cGMP level did not changed significantly. Additionally, our in vitro study showed that luzindole (a nonselective melatonin membrane receptor antagonist) or 4P-PDOT (a selective MT2 receptor antagonist) not only blocked the cytoprotective effect of melatonin, but also attenuated the stimulatory effect of melatonin on cGMP-PKGIα signaling and its modulatory effect on Nrf-2-HO-1 and MAPK signaling. This study showed that melatonin ameliorated diabetic MI/R injury by modulating Nrf-2-HO-1 and MAPK signaling, thus reducing myocardial apoptosis and oxidative stress and preserving cardiac function. Importantly, melatonin membrane receptors (especially MT2 receptor)-dependent cGMP-PKGIα signaling played a critical role in this process.

The histone methyltransferase Suv39h2 contributes to nonalcoholic steatohepatitis in mice.

Uncontrolled inflammatory response highlights the central theme of nonalcoholic steatohepatitis (NASH), a growing global pandemic. Hepatocytes and macrophages represent two major sources of hepatic inflammation during NASH pathogenesis, contributing to excessive synthesis of proinflammatory mediators. The epigenetic mechanism that accounts for the activation of hepatocytes and macrophages in this process remains obscure. Here, we report that compared to wild-type littermates, mice with a deficiency in the histone H3K9 methyltransferase suppressor of variegation 39 homolog 2 (Suv39h2, knockout) exhibited a less severe form of NASH induced by feeding with a high-fat, high-carbohydrate diet. Pro-NASH stimuli increased Suv39h2 expression in cell culture, in mice, and in human livers. In hepatocytes, Suv39h2 bound to the Sirt1 gene promoter and repressed Sirt1 transcription. Suv39h2 deficiency normalized Sirt1 expression, allowing nuclear factor kappa B/p65 to become hypoacetylated and thus dampening nuclear factor kappa B-dependent transcription of proinflammatory mediators. In macrophages, Suv39h2-mediated repression of peroxisome proliferator-activated receptor gamma transcription favored a proinflammatory M1 phenotype over an anti-inflammatory M2 phenotype, thereby elevating hepatic inflammation. CONCLUSION: Suv39h2 plays a pivotal role in the regulation of inflammatory response in hepatocytes and macrophages, contributing to NASH pathogenesis. (Hepatology 2017;65:1904-1919).

Angiogenic Factor With G Patch and FHA Domains 1 Is a Novel Regulator of Vascular Injury.

OBJECTIVE: Phenotypic modulation of vascular smooth muscle cells represents a hallmark event in vascular injury. The underlying mechanism is not completely sorted out. We investigated the involvement of angiogenic factor with G patch and FHA domains 1 (Aggf1) in vascular injury focusing on the transcriptional regulation of vascular smooth muscle cell signature genes. APPROACH AND RESULTS: We report here that Aggf1 expression was downregulated in several different cell models of phenotypic modulation in vitro and in the vessels after carotid artery ligation in mice. Adenovirus-mediated Aggf1 overexpression dampened vascular injury and normalized vascular smooth muscle cell signature gene expression. Mechanistically, Aggf1 interacted with myocardin and was imperative for the formation of a serum response factor-myocardin complex on gene promoters. In response to injurious stimuli, kruppel-like factor 4 was recruited to the Aggf1 promoter and enlisted histone deacetylase 11 to repress Aggf1 transcription. In accordance, depletion of kruppel-like factor 4 or histone deacetylase 11 restored Aggf1 expression and abrogated vascular smooth muscle cell phenotypic modulation. Finally, treatment of a histone deacetylase 11 inhibitor attenuated vascular injury in mice. CONCLUSIONS: Therefore, we have unveiled a previously unrecognized role for Aggf1 in regulating vascular injury.

Runx2/DICER/miRNA Pathway in Regulating Osteogenesis.

DICER is the central enzyme that cleaves precursor microRNAs (miRNAs) into 21-25 nucleotide duplex in cell lineage differentiation, identity, and survival. In the current study, we characterized the specific bone metabolism genes and corresponding miRNAs and found that DICER and Runt-related transcription factor 2 (Runx2) expressions increased simultaneously during osteogenic differentiation. Luciferase assay showed that Runx2 significantly increased the expression levels of DICER luciferase promoter reporter. Our analysis also revealed weaker DICER expression in embryos of Runx2 knock out mice (Runx2 -/-) compared with that of Runx2 +/- and Runx2 +/+ mice. We further established the calvarial bone critical-size defect (CSD) mouse model. The bone marrow stromal cells (BMSCs) transfected with siRNA targeting DICER were combined with silk scaffolds and transplanted into calvarial bone CSDs. Five weeks post-surgery, micro-CT analysis revealed impaired bone formation, and repairing in calvarial defects with the siRNA targeting DICER group. In conclusion, our results suggest that DICER is specifically regulated by osteogenic master gene Runx2 that binds to the DICER promoter. Consequently, DICER cleaves precursors of miR-335-5p and miR-17-92 cluster to form mature miRNAs, which target and decrease the Dickkopf-related protein 1 (DKK1), and proapoptotic factor BIM levels, respectively, leading to an enhanced Wnt/ß-catenin signaling pathway. These intriguing results reveal a central mechanism underlying lineage-specific regulation by a Runx2/DICER/miRNAs cascade during osteogenic differentiation and bone development. Our study, also suggests a potential application of modulating DICER expression for bone tissue repair and regeneration. J. Cell. Physiol. 232: 182-191, 2017. © 2016 Wiley Periodicals, Inc.

Diallyl trisulfide ameliorates myocardial ischemia-reperfusion injury by reducing oxidative stress and endoplasmic reticulum stress-mediated apoptosis in type 1 diabetic rats: role of SIRT1 activation.

Diallyl trisulfide (DATS) protects against apoptosis during myocardial ischemia-reperfusion (MI/R) injury in diabetic state, although the underlying mechanisms remain poorly defined. Previously, we and others demonstrated that silent information regulator 1 (SIRT1) activation inhibited oxidative stress and endoplasmic reticulum (ER) stress during MI/R injury. We hypothesize that DATS reduces diabetic MI/R injury by activating SIRT1 signaling. Streptozotocin (STZ)-induced type 1 diabetic rats were subjected to MI/R surgery with or without perioperative administration of DATS (40 mg/kg). We found that DATS treatment markedly improved left ventricular systolic pressure and the first derivative of left ventricular pressure, reduced myocardial infarct size as well as serum creatine kinase and lactate dehydrogenase activities. Furthermore, the myocardial apoptosis was also suppressed by DATS as evidenced by reduced apoptotic index and cleaved caspase-3 expression. However, these effects were abolished by EX527 (the inhibitor of SIRT1 signaling, 5 mg/kg). We further found that DATS effectively upregulated SIRT1 expression and its nuclear distribution. Additionally, PERK/eIF2α/ATF4/CHOP-mediated ER stress-induced apoptosis was suppressed by DATS treatment. Moreover, DATS significantly activated Nrf-2/HO-1 antioxidant signaling pathway, thus reducing Nox-2/4 expressions. However, the ameliorative effects of DATS on oxidative stress and ER stress-mediated myocardial apoptosis were inhibited by EX527 administration. Taken together, these data suggest that perioperative DATS treatment effectively ameliorates MI/R injury in type 1 diabetic setting by enhancing cardiac SIRT1 signaling. SIRT1 activation not only upregulated Nrf-2/HO-1-mediated antioxidant signaling pathway but also suppressed PERK/eIF2α/ATF4/CHOP-mediated ER stress level, thus reducing myocardial apoptosis and eventually preserving cardiac function.

Melatonin rescues cardiac thioredoxin system during ischemia-reperfusion injury in acute hyperglycemic state by restoring Notch1/Hes1/Akt signaling in a membrane receptor-dependent manner.

Stress hyperglycemia is commonly observed in patients suffering from ischemic heart disease. It not only worsens cardiovascular prognosis but also attenuates the efficacies of various cardioprotective agents. This study aimed to investigate the protective effect of melatonin against myocardial ischemia-reperfusion (MI/R) injury in acute hyperglycemic state with a focus on Notch1/Hes1/Akt signaling and intracellular thioredoxin (Trx) system. Sprague Dawley rats were subjected to MI/R surgery and high-glucose (HG, 500 g/L) infusion (4 mL/kg/h) to induce temporary hyperglycemia. Rats were treated with or without melatonin (10 mg/kg/d) during the operation. Furthermore, HG (33 mmol/L)-incubated H9c2 cardiomyoblasts were treated in the presence or absence of luzindole (a competitive melatonin receptor antagonist), DAPT (a γ-secretase inhibitor), LY294002 (a PI3-kinase/Akt inhibitor), or thioredoxin-interacting protein (Txnip) adenoviral vectors. We found that acute hyperglycemia aggravated MI/R injury by suppressing Notch1/Hes1/Akt signaling and intracellular Trx activity. Melatonin treatment effectively ameliorated MI/R injury by reducing infarct size, myocardial apoptosis, and oxidative stress. Moreover, melatonin also markedly enhanced Notch1/Hes1/Akt signaling and rescued intracellular Trx system by upregulating Notch1, N1ICD, Hes1, and p-Akt expressions, increasing Trx activity, and downregulating Txnip expression. However, these effects were blunted by luzindole, DAPT, or LY294002. Additionally, Txnip overexpression not only decreased Trx activity, but also attenuated the cytoprotective effect of melatonin. We conclude that impaired Notch1 signaling aggravates MI/R injury in acute hyperglycemic state. Melatonin rescues Trx system by reducing Txnip expression via Notch1/Hes1/Akt signaling in a membrane receptor-dependent manner. Its role as a prophylactic/therapeutic drug deserves further clinical study.

Melatonin ameliorates myocardial ischemia reperfusion injury through SIRT3-dependent regulation of oxidative stress and apoptosis.

Sirtuins are a family of highly evolutionarily conserved nicotinamide adenine nucleotide-dependent histone deacetylases. Sirtuin-3 (SIRT3) is a member of the sirtuin family that is localized primarily to the mitochondria and protects against oxidative stress-related diseases, including myocardial ischemia/reperfusion (MI/R) injury. Melatonin has a favorable effect in ameliorating MI/R injury. We hypothesized that melatonin protects against MI/R injury by activating the SIRT3 signaling pathway. In this study, mice were pretreated with or without a selective SIRT3 inhibitor and then subjected to MI/R operation. Melatonin was administered intraperitoneally (20 mg/kg) 10 minutes before reperfusion. Melatonin treatment improved postischemic cardiac contractile function, decreased infarct size, diminished lactate dehydrogenase release, reduced the apoptotic index, and ameliorated oxidative damage. Notably, MI/R induced a significant decrease in myocardial SIRT3 expression and activity, whereas the melatonin treatment upregulated SIRT3 expression and activity, and thus decreased the acetylation of superoxide dismutase 2 (SOD2). In addition, melatonin increased Bcl-2 expression and decreased Bax, Caspase-3, and cleaved Caspase-3 levels in response to MI/R. However, the cardioprotective effects of melatonin were largely abolished by the selective SIRT3 inhibitor 3-(1H-1,2,3-triazol-4-yl)pyridine (3-TYP), suggesting that SIRT3 plays an essential role in mediating the cardioprotective effects of melatonin. In vitro studies confirmed that melatonin also protected H9c2 cells against simulated ischemia/reperfusion injury (SIR) by attenuating oxidative stress and apoptosis, while SIRT3-targeted siRNA diminished these effects. Taken together, our results demonstrate for the first time that melatonin treatment ameliorates MI/R injury by reducing oxidative stress and apoptosis via activating the SIRT3 signaling pathway.

2,3,5,4'-Tetrahydroxystilbene-2-O-ß-D-glucoside protects murine hearts against ischemia/reperfusion injury by activating Notch1/Hes1 signaling and attenuating endoplasmic reticulum stress.

2,3,5,4'-Tetrahydroxystilbene-2-O-ß-D-glucoside (TSG) is a water-soluble active component extracted from Polygonum multiflorum Thunb. A number of studies demonstrate that TSG exerts cardioprotective effects. Since endoplasmic reticulum (ER) stress plays a key role in myocardial ischemia/reperfusion (MI/R)-induced cell apoptosis, we sought to determine whether modulation of the ER stress during MI/R injury was involved in the cardioprotective action of TSG. Male mice were treated with TSG (60 mg·kg-1·d-1, ig) for 2 weeks and then were subjected to MI/R surgery. Pre-administration of TSG significantly improved post-operative cardiac function, and suppressed MI/R-induced myocardial apoptosis, evidenced by the reduction in the myocardial apoptotic index, serum levels of LDH and CK after 6 h of reperfusion. TSG (0.1-1000 µmol/L) did not affect the viability of cultured H9c2 cardiomyoblasts in vitro, but pretreatment with TSG dose-dependently decreased simulated ischemia/reperfusion (SIR)-induced cell apoptosis. Furthermore, both in vivo and in vitro studies revealed that TSG treatment activated the Notch1/Hes1 signaling pathway and suppressed ER stress, as evidenced by increasing Notch1, Notch1 intracellular domain (NICD), Hes1, and Bcl-2 expression levels and by decreasing p-PERK/PERK ratio, p-eIF2α/eIF2α ratio, and ATF4, CHOP, Bax, and caspase-3 expression levels. Moreover, the protective effects conferred by TSG on SIR-treated H9c2 cardiomyoblasts were abolished by co-administration of DAPT (the Notch1 signaling inhibitor). In summary, TSG ameliorates MI/R injury in vivo and in vitro by activating the Notch1/Hes1 signaling pathway and attenuating ER stress-induced apoptosis.

A2b adenosine signaling represses CIITA transcription via an epigenetic mechanism in vascular smooth muscle cells.

Chronic inflammation plays a major role in the pathogenesis of atherosclerosis. Vascular smooth muscle cells (VSMC), by expressing and presenting major histocompatibility complex II (MHC II) molecules, help recruit T lymphocyte and initiate the inflammatory response within the vasculature. We have previously shown that VSMCs isolated from mice with deficient adenosine A2b receptor (A2b-null) exhibit higher expression of class II transactivator (CIITA), the master regulator of MHC II transcription, compared to wild type littermates. Here we report that activation of A2b adenosine signaling suppresses CIITA expression in human aortic smooth muscle cells. Down-regulation of CIITA expression was largely attributable to transcriptional repression of type III and IV promoters. Chromatin immunoprecipitation (ChIP) analyses revealed that A2b signaling repressed CIITA transcription by attenuating specific histone modifications on the CIITA promoters in a STAT1-dependent manner. STAT1 interacted with PCAF/GCN5, histone H3K9 acetyltransferases, and WDR5, a key component of the mammalian H3K4 methyltransferase complex, to activate CIITA transcription. A2b signaling prevented recruitment of PCAF/GCN5 and WDR5 to the CIITA promoters in a STAT1-dependent manner. In conclusion, our data suggest that adenosine A2b signaling represses CIITA transcription in VSMCs by manipulating the interaction between STAT1 and the epigenetic machinery.