Remifentanil postconditioning ameliorates histone H3 acetylation modification in H9c2 cardiomyoblasts after hypoxia/reoxygenation via attenuating endoplasmic reticulum stress

Management of ROS and Regulatory Cell Death in Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion injury (MIRI) is fatal to patients, leading to cardiomyocyte death and myocardial remodeling. Reactive oxygen species (ROS) and oxidative stress play important roles in MIRI. There is a complex crosstalk between ROS and regulatory cell deaths (RCD) in cardiomyocytes, such as apoptosis, pyroptosis, autophagy, and ferroptosis. ROS is a double-edged sword. A reasonable level of ROS maintains the normal physiological activity of myocardial cells. However, during myocardial ischemia-reperfusion, excessive ROS generation accelerates myocardial damage through a variety of biological pathways. ROS regulates cardiomyocyte RCD through various molecular mechanisms. Targeting the removal of excess ROS has been considered an effective way to reverse myocardial damage. Many studies have applied antioxidant drugs or new advanced materials to reduce ROS levels to alleviate MIRI. Although the road from laboratory to clinic has been difficult, many scholars still persevere. This article reviews the molecular mechanisms of ROS inhibition to regulate cardiomyocyte RCD, with a view to providing new insights into prevention and treatment strategies for MIRI.

A novel histone deacetylase inhibitor Se-SAHA attenuates isoproterenol-induced heart failure via antioxidative stress and autophagy inhibition

Heart failure is associated with histone deacetylase (HDAC) regulation of gene expression, the inhibition of which is thought to be beneficial for heart failure therapy. Here, we explored the cardioprotective effects and underlying mechanism of a novel selenium-containing HDAC inhibitor, Se-SAHA, on isoproterenol (ISO)-induced heart failure. We found that pretreatment with Se-SAHA attenuated ISO-induced cardiac hypertrophy and fibrosis in neonatal rat ventricular myocytes (NRVMs). Se-SAHA significantly attenuated the generation of ISO-induced reactive oxygen species (ROS) and restored the expression levels of superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) in vitro. Furthermore, Se-SAHA pretreatment prevented the accumulation of autophagosomes. Se-SAHA reversed the high expression of HDAC1 and HDAC6 induced by ISO incubation. However, after the addition of the HDAC agonist, the effect of Se-SAHA on blocking autophagy was inhibited. Using ISO-induced mouse models, cardiac ventricular contractile dysfunction, hypertrophy, and fibrosis was reduced treated by Se-SAHA. In addition, Se-SAHA inhibited HDAC1 and HDAC6 overexpression in ISO-treated mice. Se-SAHA treatment significantly increased the activity of SOD2 and improved the ability to eliminate free radicals. Se-SAHA hindered the excessive levels of the microtubule-associated protein 1 light chain 3 (LC3)-II and Beclin-1 in heart failure mice. Collectively, our results indicate that Se-SAHA exerts cardio-protection against ISO-induced heart failure via antioxidative stress and autophagy inhibition.

Targeting the opioid remifentanil: Protective effects and molecular mechanisms against organ ischemia-reperfusion injury

Opioids are widely used in clinical practice by activating opioid receptors (OPRs), but their clinical application is limited by a series of side effects. Researchers have been making tremendous efforts to promote the development and application of opioids. Fortunately, recent studies have identified the additional effects of opioids in addition to anesthesia and analgesia, particularly in terms of organ protection against ischemia-reperfusion (I/R) injury, with unique advantages. I/R injury in vital organs not only leads to cell dysfunction and structural damage but also induces acute and chronic organ failure, even death. Early prevention and appropriate therapeutic targets for I/R injury are crucial for organ protection. Opioids have shown cardioprotective effects for over 20 years, especially remifentanil, a derivative of fentanyl, which is a new ultra-short-acting opioid analgesic widely used in clinical anesthesia induction and maintenance. In this review, we provide current knowledge about the physiological effects related to OPR-mediated organ protection, focusing on the protective effect and mechanism of remifentanil on I/R injury in the heart and other vital organs. Herein, we also explored the potential application of remifentanil in clinical I/R injury. These findings provide a theoretical basis for the use of remifentanil to inhibit or alleviate organ I/R injury during the perioperative period and provide insights for opioid-induced human organ protection and drug development.

The role of HDAC3 and its inhibitors in regulation of oxidative stress and chronic diseases

HDAC3 is a specific and crucial member of the HDAC family. It is required for embryonic growth, development, and physiological function. The regulation of oxidative stress is an important factor in intracellular homeostasis and signal transduction. Currently, HDAC3 has been found to regulate several oxidative stress-related processes and molecules dependent on its deacetylase and non-enzymatic activities. In this review, we comprehensively summarize the knowledge of the relationship of HDAC3 with mitochondria function and metabolism, ROS-produced enzymes, antioxidant enzymes, and oxidative stress-associated transcription factors. We also discuss the role of HDAC3 and its inhibitors in some chronic cardiovascular, kidney, and neurodegenerative diseases. Due to the simultaneous existence of enzyme activity and non-enzyme activity, HDAC3 and the development of its selective inhibitors still need further exploration in the future.

Remifentanil attenuates endoplasmic reticulum stress and inflammatory injury in LPS-induced damage in HK-2 cells

Renal injury is a fatal complication in critically ill patients with sepsis. As an ultrashort-acting synthetic opioid derivative, remifentanil has been reported to mitigate renal injury and sepsis. Nevertheless, whether remifentanil also suppresses sepsis-triggered renal injury is uncertain. The aim of this study was to investigate the effect of remifentanil on endoplasmic reticulum stress (ERS) and inflammatory response in an in vitro lipopolysaccharide (LPS)-stimulated renal tubular epithelial cell (HK-2) model and its mechanism. The viability of HK-2 cells with the absence or presence of LPS treatment was surveyed by cell counting kit-8 assay. Under the condition of LPS treatment, apoptosis was appraised by TUNEL assay and western blot. Levels of inflammatory factors were estimated though corresponding kits. Western blot tested the expression of toll-like receptor 4 (TLR4)/nuclear factor-kappaB (NF-κB) signaling-associated proteins. Also, the expression of ERS-related proteins was detected by western blot. Further, ERS inducer tunicamycin (TM) was added and the aforementioned experiments were conducted again. The results underlined the protective effects of remifentanil on LPS-evoked viability injury, inflammation, activation of TLR4/NF-κB signaling and ERS in HK-2 cells. Moreover, the impacts of remifentanil on the biological events of LPS-insulted HK-2 cells were all reversed by TM administration. To conclude, remifentanil might have a remarkable ameliorative effect on sepsis-induced renal injury, which implied the potential of remifentanil-based drug therapy in sepsis-induced renal injury.

Remifentanil alleviates hypoxic-ischemic brain damage-induced cognitive impairment via BACH1

Hypoxia-ischemia (HI) is among the most frequent causes of death and disability in neonates. We aimed here to examine the neuroprotective effects of Remifentanil (RE) and the underlying mechanisms in a rat model of hypoxic-ischemic brain damage (HIBD). We found that RE improved the learning memory ability, reduced neuronal cell damage and apoptosis, reduced inflammation induced by suppressing the expression of BTB domain and CNC homolog 1 (BACH1) in rats with HIBD. BACH1 attenuated the alleviating effect of RE on cognitive impairment in HIBD rats. Moreover, RE inhibited TRAF3 expression by downregulating BACH1, and TRAF3 attenuated the therapeutic effect of RE on cognitive impairment by activating the NF-κB signaling. In conclusion, our findings demonstrated that RE inhibits the expression of BACH1, which in turn inhibits the NF-κB signaling pathway by suppressing TRAF3. RE may be a promising therapeutic agent to attenuate HIBD-induced cognitive impairment.

Remifentanil Promotes PDIA3 Expression by Activating p38MAPK to Inhibit Intestinal Ischemia/Reperfusion-Induced Oxidative and Endoplasmic Reticulum Stress

Background: Remifentanil protects against intestinal ischemia/reperfusion (I/R) injury; however, its exact mechanism remains to be elucidated. The objective of this study was to investigate the underlying molecular mechanism of remifentanil in intestinal I/R injury in mice.

Methods: We evaluated the intestine-protective effect of remifentanil in adult male mice with 45 min superior mesenteric artery occlusion followed by 4 h reperfusion by determining the following: intestinal Chiu’s scores, diamine oxidase, and intestinal fatty acid binding protein in serum; the apoptotic index, lipid peroxidation product malondialdehyde (MDA), and superoxide dismutase (SOD) activity in the intestinal mucosa; and the intestinal mRNA and protein expressions of Bip, CHOP, caspase-12, and cleaved caspase-3, reflecting endoplasmic reticulum (ER) stress. Furthermore, conditional knockout mice, in which the protein disulfide isomerase A3 (PDIA3) gene was deleted from the intestinal epithelium, and SB203580 (a selective p38MAPK inhibitor) were used to determine the role of PDIA3 and p38MAPK in I/R progression and intestinal protection by remifentanil.

Results: Our data showed that intestinal I/R induced obvious oxidative stress and endoplasmic reticulum stress–related cell apoptosis, as evidenced by an increase in the intestinal mucosal malondialdehyde, a decrease in the intestinal mucosal SOD, and an increase in the apoptotic index and the mRNA and protein expression of Bip, CHOP, caspase-12, and cleaved caspase-3. Remifentanil significantly improved these changes. Moreover, the deletion of intestinal epithelium PDIA3 blocked the protective effects of remifentanil. SB203580 also abolished the intestinal protection of remifentanil and downregulated the mRNA and protein expression of PDIA3.

Conclusion: Remifentanil appears to act via p38MAPK to protect the small intestine from intestinal I/R injury by its PDIA3-mediated antioxidant and anti-ER stress properties.

H3K23/H3K36 hypoacetylation and HDAC1 up-regulation are associated with adverse consequences in obstructive sleep apnea patients

The aim of this study is to determine the roles of global histone acetylation (Ac)/methylation (me), their modifying enzymes, and gene-specific histone enrichment in obstructive sleep apnea (OSA). Global histone modifications, and their modifying enzyme expressions were assessed in peripheral blood mononuclear cells from 56 patients with OSA and 16 matched subjects with primary snoring (PS). HIF-1α gene promoter-specific H3K36Ac enrichment was assessed in another cohort (28 OSA, 8 PS). Both global histone H3K23Ac and H3K36Ac expressions were decreased in OSA patients versus PS subjects. H3K23Ac expressions were further decreased in OSA patients with prevalent hypertension. HDAC1 expressions were higher in OSA patients, especially in those with excessive daytime sleepiness, and reduced after more than 6 months of continuous positive airway pressure treatment. H3K79me3 expression was increased in those with high C-reactive protein levels. Decreased KDM6B protein expressions were noted in those with a high hypoxic load, and associated with a higher risk for incident cardiovascular events or hypertension. HIF-1α gene promoter-specific H3K36Ac enrichment was decreased in OSA patients versus PS subjects. In vitro intermittent hypoxia with re-oxygenation stimuli resulted in HDAC1 over-expression and HIF-1α gene promoter-specific H3K36Ac under-expression, while HDAC1 inhibitor, SAHA, reversed oxidative stress through inhibiting NOX1. In conclusions, H3K23/H3K36 hypoacetylation is associated with the development of hypertension and disease severity in sleep-disordered breathing patients, probably through up-regulation of HDAC1, while H3K79 hypermethylation is associated with higher risk of cardiovascular diseases, probably through down-regulation of KDM6B.

RGFP966 inactivation of the YAP pathway attenuates cardiac dysfunction induced by prolonged hypothermic preservation

Oxidative stress and apoptosis are the key factors that limit the hypothermic preservation time of donor hearts to within 4-6 h. The aim of this study was to investigate whether the histone deacetylase 3 (HDAC3) inhibitor RGFP966 could protect against cardiac injury induced by prolonged hypothermic preservation. Rat hearts were hypothermically preserved in Celsior solution with or without RGFP966 for 12 h followed by 60 min of reperfusion. Hemodynamic parameters during reperfusion were evaluated. The expression and phosphorylation levels of mammalian STE20-like kinase-1 (Mst1) and Yes-associated protein (YAP) were determined by western blotting. Cell apoptosis was measured by the terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) method. Addition of RGFP966 in Celsior solution significantly inhibited cardiac dysfunction induced by hypothermic preservation. RGFP966 inhibited the hypothermic preservation-induced increase of the phosphorylated (p)-Mst1/Mst1 and p-YAP/YAP ratios, prevented a reduction in total YAP protein expression, and increased the nuclear YAP protein level. Verteporfin (VP), a small molecular inhibitor of YAP-transcriptional enhanced associate domain (TEAD) interaction, partially abolished the protective effect of RGFP966 on cardiac function, and reduced lactate dehydrogenase activity and malondialdehyde content. RGFP966 increased superoxide dismutase, catalase, and glutathione peroxidase gene and protein expression, which was abolished by VP. RGFP966 inhibited hypothermic preservation-induced overexpression of B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax) and cleaved caspase-3, increased Bcl-2 mRNA and protein expression, and reduced cardiomyocyte apoptosis. The antioxidant and anti-apoptotic effects of RGFP966 were cancelled by VP. The results suggest that supplementation of Celsior solution with RGFP966 attenuated prolonged hypothermic preservation-induced cardiac dysfunction. The mechanism may involve inhibition of oxidative stress and apoptosis via inactivation of the YAP pathway.

Globular adiponectin alleviates chronic intermittent hypoxia-induced H9C2 cardiomyocytes apoptosis via ER-phagy induction

This study evaluated the effects of endoplasmic reticulum autophagy (ER-phagy) and globular adiponectin (gAPN) on chronic intermittent hypoxia (CIH)-induced H9C2 cardiomyocytes injury while investigating potential mechanisms of action. The CIH model of H9C2 cardiomyocytes was established in this study. CCK-8 assay was used to determine cell viability post-exposure to various CIH times and gAPN concentrations. Flow cytometry was used to observe H9C2 cardiomyocytes apoptosis and immunofluorescence was used to measure ER-phagy and SEC62 activation. Western blot was used to observe ER stress and AMPK pathway. Results indicated that ER stress was activated in H9C2 cardiomyocytes exposed to CIH. Inhibition of ER stress reduced CIH-induced cell apoptosis. gAPN attenuated CIH-induced ER stress and H9C2 cardiomyocytes apoptosis. ER-phagy and SEC62 protein level were induced by CIH, while gAPN highly enhanced these changes. Inhibition of SEC62 expression reduced ER-phagy and increased ER stress and H9C2 cardiomyocytes apoptosis. Moreover, gAPN induced AMPK expression. Inhibition of AMPK expression reduced SEC62-mediated ER-phagy and increased the H9C2 cardiomyocytes apoptosis. Altogether, our study suggested that gAPN upregulated SEC62-mediated ER-phagy to extenuate ER stress, and mitigated H9C2 cardiomyocytes apoptosis induced by CIH through AMPK activation.

Endoplasmic reticulum stress-mediated mitochondrial dysfunction in aged hearts

Aging impairs the mitochondrial electron transport chain (ETC), especially in interfibrillar mitochondria (IFM). Mitochondria are in close contact with the endoplasmic reticulum (ER). Induction of ER stress leads to ETC injury in adult heart mitochondria. We asked if ER stress contributes to the mitochondrial dysfunction during aging. Subsarcolemmal mitochondria (SSM) and IFM were isolated from 3, 18, and 24 mo. C57Bl/6 mouse hearts. ER stress progressively increased with age, especially in 24 mo. mice that manifest mitochondrial dysfunction. OXPHOS was decreased in 24 mo. IFM oxidizing complex I and complex IV substrates. Proteomic analysis showed that the content of multiple complex I subunits was decreased in IFM from 24 mo. hearts, but remained unchanged in in 18 mo. IFM without a decrease in OXPHOS. Feeding 24 mo. old mice with 4-phenylbutyrate (4-PBA) for two weeks attenuated the ER stress and improved mitochondrial function. These results indicate that ER stress contributes to the mitochondrial dysfunction in aged hearts. Attenuation of ER stress is a potential approach to improve mitochondrial function in aged hearts.

Butyrate alleviates oxidative stress by regulating NRF2 nuclear accumulation and H3K9/14 acetylation via GPR109A in bovine mammary epithelial cells and mammary glands

Oxidative stress consistently affects lactation length and quality in dairy cows. Oxidative stress in the mammary gland of high-yielding dairy cows is a serious problem. Therefore, we studied the role of butyrate in dairy cow oxidative stress and further elucidated the mechanism of the antioxidative action of mammary epithelial cells in dairy cows. Oxidative stress and activated GPR109A were present in high-yielding dairy cows. Then, bovine mammary epithelial cells (BMECs) were isolated, and oxidative stress-related protein expression was measured, confirming that sodium butyrate (NaB) exerted antioxidant effects through GPR109A, NRF2 and H3K9/14 acetylation. To further study the antioxidative mechanism of butyrate in dairy cows, we also confirmed that butyrate promoted NRF2 nuclear accumulation and H3K9/14 acetylation through the AMPK signaling pathway by western blotting. Additionally, we preliminarily clarified the interaction between NRF2 and H3K9/14 acetylation by Co-IP and ChIP. Butyrate activated the AMPK signaling pathway through GPR109A to promote NRF2 nuclear accumulation and H3K9/14 acetylation, subsequently exerting antioxidant effects through the synergistic functions of these two processes. Then, we studied the effect of butyrate on oxidative stress in dairy cows in vivo, and the results were consistent with those in vitro. Therefore, butyrate played an antioxidant and antiapoptotic role through the GPR109A/AMPK/NRF2 signaling pathway, while H3K9/14 acetylation could promote NRF2 transcription and enhance the antioxidant capacity of BMECs.

Acetylation in cardiovascular diseases: Molecular mechanisms and clinical implications

Acetylation belongs to a class of post-translational modification (PTM) processes that epigenetically regulate gene expression and gene transcriptional activity. Reversible histone acetylation on lysine residues governs the interactions between DNA and histones to mediate chromatin remodeling and gene transcription. Non-histone protein acetylation complicates cellular function whereas acetylation of key mitochondrial enzymes regulates bioenergetic metabolism. Acetylation and deacetylation of functional proteins are essential to the delicated homeostatic regulation of embryonic development, postnatal maturation, cardiomyocyte differentiation, cardiac remodeling and onset of various cardiovascular diseases including obesity, diabetes mellitus, cardiometabolic diseases, ischemia-reperfusion injury, cardiac remodeling, hypertension, and arrhythmias. Histone acetyltransferase (HATs) and histone deacetylases (HDACs) are essential enzymes mainly responsible for the regulation of lysine acetylation levels, thus providing possible drugable targets for therapeutic interventions in the management of cardiovascular diseases.

HDAC3 Mediates Cardioprotection of Remifentanil Postconditioning by Targeting GSK-3β in H9c2 Cardiomyocytes in Hypoxia/Reoxygenation Injury

BACKGROUND

Remifentanil postconditioning (RPC) confers robust cardioprotection against ischemia/reperfusion (I/R) injury. We recently determined that HDAC3 was involved in RPC-induced cardioprotection. However, the role of HDAC3 and its possible mechanisms in RPC-induced cardioprotection are unknown, which we aimed to evaluate in an in vitro hypoxia/reoxygenation (HR) model.

METHODS

Myocardium I/R injury was established after HR with H9c2 cardiomyoblasts. Cell viability and apoptosis were evaluated usingCCK-8 and flow cytometry of HR-injured cardiomyoblasts treated with or without RPC. Furthermore, effects of RPC on HDAC3 protein and mRNA expression were evaluated with Western blot and quantitative real-time PCR analyses, whereas GSK-3β expression was measured with Western blot.

RESULTS

RPC increased cell viability and reduced cell apoptosis (P < 0.05) in H9c2 cardiomyoblasts subjected to HR injury. In addition, RPC promoted the phosphorylation of GSK-3β at Ser9 site (P < 0.05) and suppressed the protein and mRNA expression of HDAC3 (P < 0.05). Lentiviral-transduced overexpression of HDAC3 had no significant effects on HR injury while attenuating the cardioprotective effects of RPC on cell viability and apoptosis (P < 0.05), GSK-3β phosphorylation (P < 0.05) in H9c2 cardiomyoblasts.

CONCLUSIONS

RPC attenuates apoptosis in H9c2 cardiomyoblasts after HR injury by downregulating HDAC3-mediated phosphorylation of GSK-3β. Our findings suggest that HDAC3, and its cross talk function with GSK-3β, may be a promising target for myocardium I/R injury.

Suberoylanilide hydroxamic acid upregulates histone acetylation and activates endoplasmic reticulum stress to induce apoptosis in HepG2 liver cancer cells

Suberoylanilide hydroxamic acid (SAHA) is a histone deacetylase inhibitor that has demonstrated clinical activity against various solid tumors. The aim of the present study was to explore the effects of SAHA on the apoptosis of HepG2 liver cancer cells, as well as the potential mechanisms involved in histone acetylation and endoplasmic reticulum (ER) stress. HepG2 cells were treated with various doses of SAHA (0, 1, 6 and 12 µM), and apoptosis was measured by flow cytometry. The levels of ER stress-associated molecules, including 78 kDa glucose-regulated protein (GRP78), PRKR-like endoplasmic reticulum kinase (PERK), phosphorylated (p)-PERK, activating transcription factor 4 (ATF4) and C/EBP-homologous protein (CHOP), were quantitated by western blot analysis and reverse transcription-quantitative PCR assay. The expression levels of acetylated histone H4 (acH4, acH4 lysine (K)5 and acH4K12) were detected by western blot analysis. The effects of SAHA on the acetylation of H4 in the promoter regions of GRP78, ATF4 and CHOP were evaluated by chromatin immunoprecipitation assays. Following treatment with higher doses of SAHA (6 and 12 µM) for 48 h, the proliferation of HepG2 cells was significantly suppressed. SAHA induced dose-dependent apoptosis and increased both protein and mRNA expression levels of GRP78, ATF4 and CHOP in HepG2 cells. The protein expression of PERK was markedly decreased by treatment with SAHA, whereas the p-PERK expression level was notably increased, which resulted in increased p-PERK/PERK ratio. Furthermore, the acetylation levels of H4 in the promoter regions of GRP78, ATF4 and CHOP were significantly increased in HepG2 cells exposed to 6 µM SAHA for 36 h. Thus, SAHA induces apoptosis in HepG2 cells by activating the ER stress-mediated apoptotic signaling pathway, at least partially by enhancing the acetylation of histone H4 on the promoter regions of ER-stress associated genes, including GRP78, ATF4 and CHOP.

HDAC inhibition induces autophagy and mitochondrial biogenesis to maintain mitochondrial homeostasis during cardiac ischemia/reperfusion injury

AIMS

The FDA-approved histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA, Vorinostat) has been shown to induce cardiomyocyte autophagy and blunt ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, the precise mechanisms underlying the cardioprotective activity of SAHA are unknown. Mitochondrial dysfunction and oxidative damage are major contributors to myocardial apoptosis during I/R injury. We hypothesize that SAHA protects the myocardium by maintaining mitochondrial homeostasis and reducing reactive oxygen species (ROS) production during I/R injury.

METHODS

Mouse and cultured cardiomyocytes (neonatal rat ventricular myocytes and human embryonic stem cell-derived cardiomyocytes) I/R models were used to investigate the effects of SAHA on mitochondria. ATG7 knockout mice, ATG7 knockdown by siRNA and PGC-1α knockdown by adenovirus in cardiomyocytes were used to test the dependency of autophagy and PGC-1α-mediated mitochondrial biogenesis respectively.

RESULTS

Intact and total mitochondrial DNA (mtDNA) content and mitochondrial mass were significantly increased in cardiomyocytes by SAHA pretreatment before simulated I/R. In vivo, I/R induced >50% loss of mtDNA content in the border zones of mouse hearts, but SAHA pretreatment and reperfusion treatment alone reverted mtDNA content and mitochondrial mass to control levels. Moreover, pretreatment of cardiomyocytes with SAHA resulted in a 4-fold decrease in I/R-induced loss of mitochondrial membrane potential and a 25%-40% reduction in cytosolic ROS levels. However, loss-of-function of ATG7 in cardiomyocytes or mouse myocardium abolished the protective effects of SAHA on ROS levels, mitochondrial membrane potential, mtDNA levels, and mitochondrial mass. Lastly, PGC-1α gene expression was induced by SAHA in NRVMs and mouse heart subjected to I/R, and loss of PGC-1α abrogated SAHA's mitochondrial protective effects in cardiomyocytes.

CONCLUSIONS

SAHA prevents I/R induced-mitochondrial dysfunction and loss, and reduces myocardial ROS production when given before or after the ischemia. The protective effects of SAHA on mitochondria are dependent on autophagy and PGC-1α-mediated mitochondrial biogenesis.

β-hydroxybutyrate attenuates renal ischemia-reperfusion injury through its anti-pyroptotic effects

Ketone bodies including β-hydroxybutyrate (β-OHB) have been shown to protect against ischemic tissue injury when present at low concentrations. We evaluated the impact of β-OHB on renal ischemia/reperfusion injury (IRI). Mice were treated with a continuous infusion of β-OHB using an osmotic mini-pump before and after IRI. We also tested the effects of increasing endogenous serum β-OHB levels by fasting. Renal IRI was attenuated by β-OHB treatment compared to saline control, with similar results in the fasting condition. β-OHB treatment reduced the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and increased expression of forkhead transcription factor O3 (FOXO3), an upstream regulator of pyroptosis. Although β-OHB treatment did not impact markers of apoptosis, it decreased the expression of caspase-1 and proinflammatory cytokines, indicating that β-OHB blocked pyroptosis. In a human proximal tubular cell line exposed to hypoxia and reoxygenation, β-OHB reduced cell death in a FOXO3-dependent fashion. Histone acetylation was decreased in kidneys exposed to IRI and in proximal tubular cells exposed to hypoxia and reoxygenation, and this effect was ameliorated by β-OHB through the inactivation of histone deacetylases. In vitro, β-OHB treatment restored histone acetylation at the FOXO3 promoter. Consistent with epigenetic molecular effects, the renoprotective effects of β-OHB were still observed when the continuous infusion was stopped at the time of IRI. Thus, β-OHB attenuates renal IRI through anti-pyroptotic effects, likely mediated by an epigenetic effect on FOXO3 expression.

Astragaloside IV ameliorates endoplasmic reticulum stress‑induced apoptosis of Aβ25‑35‑treated PC12 cells by inhibiting the p38 MAPK signaling pathway

Endoplasmic reticulum stress (ERS) serves a vital role in the pathological development of Alzheimer's disease (AD). ERS can promote programmed cell death (apoptosis) during AD; however, the specific molecular mechanisms that lead to ERS remain unclear. It is very important that a drug for the treatment of AD is identified. Our previous studies indicated that astragaloside IV (AST IV) has anti-inflammatory effects and helps cells resist oxidative stress. In the present study, western blotting and reverse transcription semi-quantitative polymerase chain reaction were used to detect protein and mRNA expression levels, flow cytometry was used to measure intracellular reactive oxygen species (ROS) levels, and superoxide dismutase (SOD) and malondialdehyde (MDA) activity was detected using commercially available kits. The results demonstrated that SOD activity was decreased, and MDA content, ROS levels, and the expression levels of p38 mitogen-activated protein kinase (MAPK) and ERS-associated proteins, including binding immunoglobulin protein/glucose-regulated protein and growth arrest- and DNA damage -inducible gene 153/C/EBP homologous protein, were increased in amyloid β (Aβ)_25-35-treated PC12 cells. Furthermore, to investigate the role of p38 MAPK and the effects of AST IV in an in vitro model of AD, SB203580, a p38 MAPK signaling pathway inhibitor, and AST IV were administered to Aβ_25-35-treated PC12 cells. The results revealed that AST IV protected the cells against AD. This effect may be caused by decreases in ROS levels, which may inhibit the p38 MAPK signaling pathway and thereby suppress ERS in Aβ_25-35-treated PC12 cells.