Retinol dehydrogenase 10 reduction mediated retinol metabolism disorder promotes diabetic cardiomyopathy in male mice.

Diabetic cardiomyopathy is a primary myocardial injury induced by diabetes with complex pathogenesis. In this study, we identify disordered cardiac retinol metabolism in type 2 diabetic male mice and patients characterized by retinol overload, all-trans retinoic acid deficiency. By supplementing type 2 diabetic male mice with retinol or all-trans retinoic acid, we demonstrate that both cardiac retinol overload and all-trans retinoic acid deficiency promote diabetic cardiomyopathy. Mechanistically, by constructing cardiomyocyte-specific conditional retinol dehydrogenase 10-knockout male mice and overexpressing retinol dehydrogenase 10 in male type 2 diabetic mice via adeno-associated virus, we verify that the reduction in cardiac retinol dehydrogenase 10 is the initiating factor for cardiac retinol metabolism disorder and results in diabetic cardiomyopathy through lipotoxicity and ferroptosis. Therefore, we suggest that the reduction of cardiac retinol dehydrogenase 10 and its mediated disorder of cardiac retinol metabolism is a new mechanism underlying diabetic cardiomyopathy.

Targeting ACSL1 promotes cardiomyocyte proliferation and cardiac regeneration.

BACKGROUND: Neonatal hearts have considerable regenerative potential within 7 days post birth (P7), but the rate of regeneration is extremely low after P7. Interestingly, lipid metabolism increases dramatically after P7. The similarities in these age profiles suggests a possible link between cardiac regeneration and lipid metabolism. Acyl CoA synthase long chain family member 1 (ACSL1) is the key enzyme that regulates lipid metabolism. The aim of this study was to identify the role of ACSL1 in the regeneration of cardiomyocytes. METHODS AND RESULTS: The uptake of fatty acids in hearts increased after P7; however, myocardial regeneration was decreased. We profiled an RNA-sequence array of hearts from mice of different ages, including E10.5 (embryonic stage)-, 3-, 7-, 21-, 30-, and 60-day-old mice, and found that the expression of ACSL1 was significantly increased after P7. By establishing ACSL1 knockdown mice with adeno-associated virus (AAV9). Then, we verified that knockdown of ACSL1 enhanced the capacity for myocardial regeneration both in mice and in primary cardiomyocytes. Indeed, ACSL1 knockdown in primary cardiomyocytes promoted the cell cycle progression from G0 to G2 phase by regulating specific factors, which may correlate with the activation of AKT by ACSL1 and withdrawal of FOXO1 from the nucleus. In vivo, knockdown of ACSL1 effectively restored cardiac function and myocardial regeneration in adult mice with myocardial infarction (MI). CONCLUSIONS: ACSL1 possibly induces the loss of the myocardial regenerative potential beginning at P7 in mice, and inhibition of ACSL1 effectively promoted myocardial repair after MI in mice.

Hsp90 inhibitor induces KG-1a cell differentiation and apoptosis via Akt/NF-κB signaling.

Heat-shock protein 90 (Hsp 90) acts as a molecular chaperone that maintains protein stability and regulates cell proliferation, survival, differentiation and apoptosis. The present study investigated the effect of Hsp90 inhibition on human acute myeloid leukemia (AML) cells using the novel small-molecule inhibitor SNX-2112. We found that SNX-2112 more potently inhibited KG-1a cell growth than the classical Hsp90 inhibitor 17-(2-dimethylaminoethyl)amino­17-demethoxygeldanamycin as determined by CCK-8 assay. Flow cytometry was used to examine the cell cycle, differentiation, and apoptosis, and western blotting and qRT-PCR were used to analyze the underlying mechanism. The results revealed that low concentrations of SNX-2112 arrested the cells in the G2/M phase and induced their differentiation and apoptosis, possibly by suppressing Akt and inhibitor of κB kinase, a component of the nuclear factor (NF)-κB signaling pathway. We also found that SNX-2112 increased the expression of the differentiation transcription factors PU.1 and CCAAT­enhancer-binding protein-α. Thus, SNX-2112 induced KG-1a cell differentiation, cell cycle arrest and apoptosis via modulation of Akt and NF-κB signaling, suggesting that it is a promising therapeutic agent for the treatment of AML.

Inhibition of glycogen synthase kinase 3beta ameliorates triptolide-induced acute cardiac injury by desensitizing mitochondrial permeability transition.

Triptolide (TP), a diterpene triepoxide, is a major active component of Tripterygium wilfordii extracts, which are prepared as tablets and has been used clinically for the treatment of inflammation and autoimmune disorders. However, TP's therapeutic potential is limited by severe adverse effects. In a previous study, we reported that TP induced mitochondria dependent apoptosis in cardiomyocytes. Glycogen synthase kinase-3ß (GSK-3ß) is a multifunctional serine/threonine kinase that plays important roles in the necrosis and apoptosis of cardiomyocytes. Our study aimed to investigate the role of GSK-3ß in TP-induced cardiotoxicity. Inhibition of GSK-3ß activity by SB 216763, a potent and selective GSK-3 inhibitor, prominently ameliorated the detrimental effects in C57BL/6J mice with TP administration, which was associated with a correction of GSK-3ß overactivity. Consistently, in TP-treated H9c2 cells, SB 216763 treatment counteracted GSK-3ß overactivity, improved cell viability, and prevented apoptosis by modulating the expression of Bcl-2 family proteins. Mechanistically, GSK-3ß interacted with and phosphorylated cyclophilin F (Cyp-F), a key regulator of mitochondrial permeability transition pore (mPTP). GSK-3ß inhibition prevented the phosphorylation and activation of Cyp-F, and desensitized mPTP. Our findings suggest that pharmacological targeting of GSK-3ß could represent a promising therapeutic strategy for protecting against cardiotoxicity induced by TP.

Tanshinone IIA protects against acetaminophen-induced hepatotoxicity via activating the Nrf2 pathway.

BACKGROUND: Tanshinone IIA (Tan), the main active component of Salvia miltiorrhiza, has been demonstrated to have antioxidant activity. Acetaminophen (APAP), a widely used antipyretic and analgesic, can cause severe hepatotoxicity and liver failure when taken overdose. Oxidative stress has been reported to be involved in APAP-induced liver failure. PURPOSE: This study aimed to investigate the effect of Tan on APAP-induced hepatotoxicity and the underlying mechanisms involved. STUDY DESIGN: C57BL/6J mice were divided into six groups: (1) control, (2) APAP group, (3) APAP+Tan (30mg/kg) group, (4) Tan (30mg/kg) group, (5) APAP+Tan (10mg/kg) group, (6) Tan (10mg/kg) group. Mice in group 3 and 5 were pre-treated with specified dose of Tan by gavage and subsequently injected with an overdose of APAP intraperitoneally (i.p., 300mg/kg). The effect of Tan on Nrf2 pathway was investigated in HepG2 cells and mice. METHODS: Plasma aspartate transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), liver glutathione (GSH), glutathione transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) levels were determined after mice were sacrificed. Lipid peroxidation and histological examination were performed. The effect of Tan on the Nrf2 pathway was detected by western blotting and qRT-PCR. RESULTS: Tan pretreatment reduced APAP-induced liver injury. Tan was able to activate Nrf2 and increase the expression levels of Nrf2 target genes, including glutamate-cysteine ligase catalytic subunit (GCLC), NAD(P)H:quinine oxidoreductase 1 (NQO1) and hemeoxygenase-1 (HO-1), in a dose-dependent manner in HepG2 cells. Consistent with our observations in HepG2 cells, Tan increased nuclear Nrf2 accumulation and upregulated mRNA and protein levels of the Nrf2 target genes GCLC, NQO1 and HO-1 in C57BL/6J mice compared with mice treated with APAP alone. CONCLUSIONS: Our results demonstrate that Tan pretreatment could protect the liver from APAP-induced hepatic injury by activating the Nrf2 pathway. Tan may provide a new strategy for the protection against APAP-induced liver injury.

Activation of the farnesoid X receptor attenuates triptolide-induced liver toxicity.

BACKGROUND: Triptolide, an active ingredient extracted from the Chinese herb Tripterygium wilfordii Hook f., has multiple pharmacological properties, including anti-inflammatory, immune-modulatory, and anti-proliferative activities. However, the hepatotoxicity of triptolide always limits its clinical applications. HYPOTHESIS/PURPOSE: Farnesoid X receptor (FXR) is a ligand-activated transcription factor that plays a key role in hepatoprotection through the maintenance of liver metabolism homeostasis. This study explored the role of FXR in triptolide-induced cytotoxicity and investigated whether activation of FXR can protect against triptolide-induced liver injury. STUDY DESIGN: The role of FXR in triptolide-induced cytotoxicity was investigated in HepG2 cells. In addition, the protective effect of the selective FXR agonist GW4064 on triptolide-induced hepatotoxicity was explored in BALB/c mice. METHODS: HepG2 cells were transient transfected with FXR expression plasmid or FXR-siRNA. The cytotoxicity was compared using the MTT assay. The extent of liver injury was assessed by histopathology and serum aminotransferases. The expression of FXR and its target genes were detected by Western blot and qRT-PCR. RESULTS: The transient overexpression of FXR protected against triptolide-induced cell death, whereas FXR knockdown with a specific small interfering RNA resulted in increased cytotoxicity. In BALB/c mice, treatment with the FXR agonist GW4064 attenuated triptolide-induced liver dysfunction, structural damage, glutathione depletion and lipid peroxidation. Moreover, the livers of GW4064-treated mice showed increased expression of FXR and several related target genes involved in phase II and phase III xenobiotic metabolism. CONCLUSION: Taken together, these results indicate that activation of FXR attenuates triptolide-induced hepatotoxicity and provide direct implications for the development of novel therapeutic strategies against triptolide-induced hepatotoxicity.

Activation of Nrf2 protects against triptolide-induced hepatotoxicity.

Triptolide, the major active component of Tripterygium wilfordii Hook f. (TWHF), has a wide range of pharmacological activities. However, the toxicities of triptolide, particularly the hepatotoxicity, limit its clinical application. The hepatotoxicity of triptolide has not been well characterized yet. The aim of this study was to investigate the role of NF-E2-related factor 2 (Nrf2) in triptolide-induced toxicity and whether activation of Nrf2 could protect against triptolide-induced hepatotoxicity. The results showed that triptolide caused oxidative stress and cell damage in HepG2 cells, and these toxic effects could be aggravated by Nrf2 knockdown or be counteracted by overexpression of Nrf2. Treatment with a typical Nrf2 agonist, sulforaphane (SFN), attenuated triptolide-induced liver dysfunction, structural damage, glutathione depletion and decrease in antioxidant enzymes in BALB/C mice. Moreover, the hepatoprotective effect of SFN on triptolide-induced liver injury was associated with the activation of Nrf2 and its downstream targets. Collectively, these results indicate that Nrf2 activation protects against triptolide-induced hepatotoxicity.