Cardiac Metabolism, Reprogramming, and Diseases.

Cardiovascular diseases (CVD) account for the largest bulk of deaths worldwide, posing a massive burden on societies and the global healthcare system. Besides, the incidence and prevalence of these diseases are on the rise, demanding imminent action to revert this trend. Cardiovascular pathogenesis harbors a variety of molecular and cellular mechanisms among which dysregulated metabolism is of significant importance and may even proceed other mechanisms. The healthy heart metabolism primarily relies on fatty acids for the ultimate production of energy through oxidative phosphorylation in mitochondria. Other metabolites such as glucose, amino acids, and ketone bodies come next. Under pathological conditions, there is a shift in metabolic pathways and the preference of metabolites, termed metabolic remodeling or reprogramming. In this review, we aim to summarize cardiovascular metabolism and remodeling in different subsets of CVD to come up with a new paradigm for understanding and treatment of these diseases.

Spatial-temporal proliferation of hepatocytes during pregnancy revealed by genetic lineage tracing.

The maternal liver undergoes dramatic enlargement to adapt to the increased metabolic demands during pregnancy. However, the cellular sources for liver growth during pregnancy remain largely elusive. Here, we employed a proliferation recording system, ProTracer, to examine the spatial-temporal proliferation of hepatocytes during pregnancy. We discovered that during early to late pregnancy, hepatocyte proliferation initiated from zone 1, to zone 2, and lastly to zone 3, with the majority of new hepatocytes being generated in zone 2. Additionally, using single-cell RNA sequencing, we observed that Ccnd1 was highly enriched in zone 2 hepatocytes. We further applied dual-recombinase-mediated genetic lineage tracing to reveal that Ccnd1+ hepatocytes expanded preferentially during pregnancy. Moreover, we demonstrated that estrogen induces liver enlargement during pregnancy, which was abolished in Ccnd1 knockout mice. Our work revealed a unique spatial-temporal hepatocyte proliferation pattern during pregnancy, with Ccnd1+ hepatocytes in zone 2 serving as the major cellular source for hepatic enlargement.

Mitochondrial aldehyde dehydrogenase rescues against diabetic cardiomyopathy through GSK3ß-mediated preservation of Mitochondrial integrity and parkin-mediated mitophagy.

Mitochondrial aldehyde dehydrogenase (ALDH2) offers proven cardiovascular benefit although its impact in diabetes remains elusive. This study examined the effect of ALDH2 overexpression (OE) and knockout (KO) on diabetic cardiomyopathy and mechanism involved with a focus on mitochondrial integrity. ALDH2 OE and KO mice were challenged with streptozotocin (STZ, 200 mg/kg. i.p.) to establish diabetes. Diabetic patients displayed reduced plasma ALDH2 activity, cardiac remodeling and diastolic dysfunction. STZ challenge prompted reduced respiratory exchange ratio (RER), dampened fractional shortening, ejection fraction, increased LV end systolic and diastolic diameters, cardiac remodeling, cardiomyocyte contractile and intracellular Ca2+ defects (depressed peak shortening and maximal velocity of shortening/relengthening, prolonged relengthening, dampened intracellular Ca2+ rise and clearance), myocardial ultrastructural injury, oxidative stress, apoptosis and mitochondrial damage, the effects of which were overtly attenuated and accentuated by ALDH2 OE and KO, respectively. Immunoblotting revealed downregulated mitochondrial proteins PPARγ coactivator 1α (PGC-1α) and UCP-2, Ca2+ regulatory proteins including SERCA and Na+-Ca2+ exchanger, elevated phospholamban, dampened autophagy and mitophagy (LC3B ratio, TOM20, Parkin, FUNDC1 and BNIP3), disrupted phosphorylation of Akt, GSK3ß and Foxo3a, and elevated PTEN phosphorylation, the effect of which was reversed and worsened by ALDH2 OE and KO, respectively (except FUNDC1 and BNIP3). In vivo and in vitro data revealed that novel ALDH2 activator torezolid/Alda-1 protected against STZ or high glucose-induced cardiac anomalies, the effect was nullified by inhibition of Akt, GSK3ß, Parkin and mitochondrial coupling. Our data discerned a vital role for ALDH2 in diabetic cardiomyopathy possibly through regulation of Akt, GSK3ß activation, parkin mitophagy and mitochondrial function.

Exosomes derived from pericardial adipose tissues attenuate cardiac remodeling following myocardial infarction by Adipsin-regulated iron homeostasis.

As a vital adipokine, Adipsin is closely associated with cardiovascular risks. Nevertheless, its role in the onset and development of cardiovascular diseases remains elusive. This study was designed to examine the effect of Adipsin on survival, cardiac dysfunction and adverse remodeling in the face of myocardial infarction (MI) injury. In vitro experiments were conducted to evaluate the effects of Adipsin on cardiomyocyte function in the face of hypoxic challenge and the mechanisms involved. Our results showed that Adipsin dramatically altered expression of proteins associated with iron metabolism and ferroptosis. In vivo results demonstrated that Adipsin upregulated levels of Ferritin Heavy Chain (FTH) while downregulating that of Transferrin Receptor (TFRC) in peri-infarct regions 1 month following MI. Adipsin also relieved post-MI-associated lipid oxidative stress as evidenced by decreased expression of COX2 and increased GPX4 level. Co-immunoprecipitation and immunofluorescence imaging prove a direct interaction between Adipsin and IRP2. As expected, cardioprotection provided by Adipsin depends on the key molecule of IRP2. These findings revealed that Adipsin could be efficiently delivered to the heart by exosomes derived from pericardial adipose tissues. In addition, Adipsin interacted with IRP2 to protect cardiomyocytes against ferroptosis and maintain iron homeostasis. Therefore, Adipsin-overexpressed exosomes derived from pericardial adipose tissues may be a promising therapeutic strategy to prevent adverse cardiac remodeling following ischemic heart injury.

Exercise alleviates cardiac remodelling in diabetic cardiomyopathy via the miR-486a-5p-Mst1 pathway.

OBJECTIVES: Physical exercise has emerged as an effective therapy to mitigate cardiac remodelling in diabetic cardiomyopathy (DCM). The results of our previous studies revealed mammalian sterile 20-like kinase 1 (Mst1) is a key regulator of the progression of DCM. However, the precise molecular mechanism of physical exercise-induced cardiac protection and its association with Mst1 inhibition remain unclear. MATERIALS AND METHODS: Wildtype and Mst1 transgenic mice were challenged with streptozotocin (STZ) to induce experimental diabetes and were divided into sedentary and exercise groups. The DCM phenotype was evaluated by echocardiography, Masson's trichrome staining, TUNEL and immunoblotting analyses. The exercise-regulated miRNAs targeting Mst1 were predicted by bioinformatic analysis and later confirmed by RT-qPCR, immunoblotting, and dual-luciferase reporter assays. In addition, cultured neonatal mouse cardiomyocytes were subjected to simulate diabetes to elucidate the underlying mechanisms. RESULTS: Compared to the sedentary diabetic control, physical exercise inhibited Mst1 and alleviated cardiac remodelling in mice with DCM, as evidenced by decreases in the left ventricular end-systolic internal dimension (LVESD) and left ventricular end-diastolic internal dimension (LVEDD), increases in the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), attenuation of collagen deposition, and the suppression of apoptosis. Bioinformatic analysis and apoptosis assessments revealed exercise exerted protective effects against DCM through miR-486a-5p release. Moreover, luciferase reporter assays confirmed miR-486a-5p directly suppressed the expression of Mst1, thereby inhibiting the apoptosis of cardiomyocytes subjected to high glucose treatment. CONCLUSION: Physical exercise inhibits cardiac remodelling in DCM, and the mechanism is associated with miR-486a-5p release-induced Mst1 inhibition.

Biodegradable polymer-coated versus durable polymer-coated sirolimus-eluting stents: the final 5-year outcomes of the I-LOVE-IT 2 trial.

AIMS: This analysis presents the final five-year results of the I-LOVE-IT 2 trial, a non-inferiority study comparing a biodegradable polymer (BP) sirolimus-eluting stent (SES) with a durable polymer (DP) SES in patients with coronary artery disease. METHODS AND RESULTS: Overall, 2,737 Chinese patients eligible for coronary stenting were treated with BP-SES or DP-SES in a 2:1 ratio. Patients who were randomised to the BP-SES group were additionally re-randomised to receive either six-month or 12-month dual antiplatelet therapy (DAPT) in a 1:1 ratio. The primary endpoint was 12-month target lesion failure (TLF: cardiac death, target vessel myocardial infarction (MI), or clinically indicated target lesion revascularisation). At five years, the overall follow-up rate was 90.8%, and the cumulative incidence of TLF as the primary endpoint was similar between BP-SES and DP-SES (hazard ratio [HR] 1.01, 95% confidence interval [CI]: 0.79 to 1.28), as was that for the patient-oriented composite endpoint (PoCE: all-cause death, all MI and any revascularisation) (HR 1.03, 95% CI: 0.86 to 1.23), or definite/probable stent thrombosis (ST) (HR 0.91, 95% CI: 0.70 to 1.77). Cumulative events were also similar between the six-month DAPT and 12-month DAPT groups after BP-SES implantation. CONCLUSIONS: I-LOVE-IT 2 showed that the five-year safety and efficacy of BP-SES and DP-SES were similar, as were those between six months and 12 months of DAPT after BP-SES implantation.

MiR-223/NFAT5 signaling suppresses arterial smooth muscle cell proliferation and motility in vitro.

Aberrant proliferation and migration of vascular smooth muscle cells contributes to cardiovascular diseases (CVDs), including atherosclerosis. MicroRNA-223 (miR-223) protects against atherosclerotic CVDs. We investigated the contribution of miR-223 to platelet-derived growth factor-BB (PDGF-BB)-induced proliferation and migration of human aortic smooth muscle cells (HASMCs). We found that miR-223 was downregulated in PDGF-BB-treated HASMCs in a dose- and time-dependent manner, while nuclear factor of activated T cells 5 (NFAT5) was upregulated. Gain- and loss-of-function studies demonstrated that miR-223 treatment reduced PDGF-BB-induced HASMC proliferation and motility, whereas miR-223 inhibitor enhanced these processes. Moreover, NFAT5 was identified as a direct target of miR-223 in HASMC. The inhibitory effects of miR-223 on HASMC proliferation and migration were partly rescued by NFAT5 restoration. Overall, these findings suggest that miR-223 inhibits the PDGF-BB-induced proliferation and motility of HASMCs by targeting NFAT5 and that miR-223 and NFAT5 may be potential therapeutic targets for atherosclerosis.

SHANK3 Co-ordinately Regulates Autophagy and Apoptosis in Myocardial Infarction.

Cardiac remodeling and dysfunction are responsible for the high mortality after myocardial infarction (MI). We assessed the potential for Shank3 to alleviate the post-infarction cardiac dysfunction. The experimental MI mice model was constructed by left anterior descending coronary artery ligation. Shank3 knockout aggravated cardiac dysfunction after MI, while Shank3 overexpression alleviated it. The histological examination showed that the infarct size was significantly increased in the acute phase of MI in the Shank3 knockout group, and the cardiac dysfunction of the Shank3 knockout group was even more severe than the Shank3 overexpression group, revealed by echocardiography analyses. In vitro, cultured neonatal cardiomyocytes were subjected to simulated MI. Shank3 downregulation curbed LC3 expression and autophagosome-lysosome fusion. Furthermore, Shank3 downregulation increased cardiomyocyte apoptosis. In contrast, Shank3 upregulation induced autophagy, and inhibited apoptosis under hypoxia. In vivo, western blot analysis showed decreased levels of Atg7, Beclin1, LC3-II, and Bcl-2 as well as increased expression of p62, cleaved caspase-3, and cleaved caspase-9 in the Shank3 knockout group which suffered from MI. On the other hand, it also revealed that Shank3 overexpression induced autophagy and inhibited apoptosis after MI. Shank3 may serve as a new target for improving cardiac function after MI by inducing autophagy while inhibiting apoptosis.

Mst1 knockdown alleviates cardiac lipotoxicity and inhibits the development of diabetic cardiomyopathy in db/db mice.

Diabetic cardiomyopathy (DCM) accounts for increasing deaths of diabetic patients, and effective therapeutic targets are urgently needed. Myocardial lipotoxicity, which is caused by cardiac non-oxidative metabolic fatty acids and cardiotoxic fatty acid metabolites accumulation, has gained more attention to explain the increasing prevalence of DCM. However, whether mammalian Ste20-like kinase 1 (Mst1) plays a role in lipotoxicity in type 2 diabetes-induced cardiomyopathy has not yet been illustrated. Here, we found that Mst1 expression was elevated transcriptionally in the hearts of type 2 diabetes mellitus mice and palmitic acid-treated neonatal rat ventricular myocytes. Adeno-associated virus 9 (AAV9)-mediated Mst1 silencing in db/db mouse hearts significantly alleviated cardiac dysfunction and fibrosis. Notably, Mst1 knockdown in db/db mouse hearts decreased lipotoxic apoptosis and inflammatory response. Mst1 knockdown exerted protective effects through inactivation of MAPK/ERK kinase kinase 1 (MEKK1)/c-Jun N-terminal kinase (JNK) signaling pathway. Moreover, lipotoxicity induced Mst1 expression through promoting the binding of forkhead box O3 (FoxO3) and Mst1 promoter. Conclusively, we elucidated for the first time that Mst1 expression is regulated by FOXO3 under lipotoxicity stimulation and downregulation of Mst1 protects db/db mice from lipotoxic cardiac injury through MEKK1/JNK signaling inhibition, indicating that Mst1 abrogation may be a potential treatment strategy for DCM in type 2 diabetic patients.

One-year clinical results of the NANO registry: A multicenter, prospective all-comers registry study in patients receiving implantation of a polymer-free sirolimus-eluting stent.

OBJECTIVES: We aimed to evaluate the safety and efficacy of Nano+™ (Lepu Medical, Beijing, China) stent implantation in all-comer patients at the 1-year follow-up. BACKGROUND: The Nano+™ stent is a novel polymer-free sirolimus-eluting stent polymer that employs nanoporous stent surface technology to control drug-delivery. The Nano+™ stent is one of the most widely used drug-eluting stent (DES) in China. METHODS: A total of 2,481 consecutive patients were included in the multicenter and prospective NANO registry. In this study, the primary endpoint was target lesion failure (TLF) at 1-year follow-up, defined as a composite of cardiac death, target vessel nonfatal myocardial infarction (TV-MI), and clinically driven target lesion revascularization (TLR). The safety endpoint was the occurrence of definite or probable stent thrombosis (ST). RESULTS: Up to 40.2% of patients presented with acute myocardial infarction (AMI). A total of 63.9% of the 2,904 lesions were American College of Cardiology/American Heart Association (ACC/AHA) type B2 or C lesions. One-year follow-up data were available for 98.4% of patients. The 1-year rate of TLF was 3.1% with rates of 1.3, 1.8, and 0.4% for clinically driven TLR, cardiac death, and TV-MI, respectively. ST occurred in 0.4% of patients. Diabetes mellitus, AMI, left ventricular ejection fraction <40% and long lesions (>40 mm) were independent predictors of 1-year TLF. CONCLUSIONS: The 1-year clinical outcomes were excellent for Nano+™ polymer-free SES implantation in an all-comer patient population. Follow-up will be extended up to 5 years, to further elucidate the potential long-term clinical benefits. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02929030.

Mst1 Knockout Alleviates Mitochondrial Fission and Mitigates Left Ventricular Remodeling in the Development of Diabetic Cardiomyopathy.

The disruption of mitochondrial dynamics is responsible for the development of diabetic cardiomyopathy (DCM). However, the mechanisms that regulate the balance of mitochondrial fission and fusion are not well-understood. Wild-type, Mst1 transgenic and Mst1 knockout mice were induced with experimental diabetes by streptozotocin injection. In addition, primary neonatal cardiomyocytes were isolated and cultured to simulate diabetes to explore the mechanisms. Echocardiograms and hemodynamic measurements revealed that Mst1 knockout alleviated left ventricular remodeling and cardiac dysfunction in diabetic mice. Mst1 knockdown significantly decreased the number of TUNEL-positive cardiomyocytes subjected to high-glucose (HG) medium culture. Immunofluorescence study indicated that Mst1 overexpression enhanced, while Mst1 knockdown mitigated mitochondrial fission in DCM. Mst1 participated in the regulation of mitochondrial fission by upregulating the expression of Drp1, activating Drp1S616 phosphorylation and Drp1S637 dephosphorylation, as well as promoting Drp1 recruitment to the mitochondria. Furthermore, Drp1 knockdown abolished the effects of Mst1 on mitochondrial fission, mitochondrial membrane potential and mitochondrial dysfunction in cardiomyocytes subjected to HG treatment. These results indicated that Mst1 knockout inhibits mitochondrial fission and alleviates left ventricular remodeling thus prevents the development of DCM.

Sirt6 stabilizes atherosclerosis plaques by promoting macrophage autophagy and reducing contact with endothelial cells.

Sirt6 has been reported to play a protective role in macrophage foam cell formation, but whether Sirt6 controls atherosclerosis plaque stability and whether it can reduce the interaction between endothelial cells and macrophages remains unclear. The aim of this study was to investigate the effect of Sirt6 on atherosclerosis plaque stability and the underlying mechanisms. We used Tie2-Cre transgenic mice as a Cre-lox tool to delete Sirt6 floxed sequences in endothelial cells during adulthood to establish Sirt6-/- mice. ApoE-/-:Sirt6-/- and ApoE-/-:Sirt6Tg mice were used in our investigation. After a 16 week high-fat diet, the mice developed markedly atherosclerotic plaques. Sirt6 knockout exacerbated atherosclerotic plaque progression in both size and stability. In vitro, murine macrophage RAW264.7 cells were treated with ox-low density lipoproteins for 24 h to simulate atherosclerosis. Furthermore, Sirt6 overexpression remarkably increased autophagic flux in macrophages and inhibited macrophage apoptosis. Moreover, Sirt6 overexpression inhibited the expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and platelet selectin (P-selectin), leading to reduced infiltration of macrophages and foam cells. In conclusion, our study indicates a new mechanism-based strategy to therapeutically stimulate atherosclerosis plaque stability.

Essential Role Of High Glucose-Induced Overexpression Of PKCß And PKCδ In GLP-1 Resistance In Rodent Cardiomyocytes.

PURPOSE: Myocardia in diabetic patients exhibit increased vulnerability after ischemia/reperfusion injury (IRI). It has been demonstrated that glucagon-like peptide-1 (GLP-1) has a protective effect on cardiomyocytes. Protein kinase C (PKC) acts as a key regulator of many signaling pathways including oxidative stress and apoptosis. Our hypothesis is that increased vulnerability of myocardia in diabetic patients is partly due to GLP-1 resistance. The aim of this study was to explore the role of PKC in GLP-1 resistance in diabetic cardiomyocytes. METHODS: Cardiac function of diabetic or non-diabetic mice after myocardial IRI was detected with or without administration of GLP-1 analog exendin-4. Impacts of diabetes mellitus on GLP-1R expression in myocardia after IRI were accessed by Western blot. By transfecting PKC isoforms siRNA, in vitro study helped to identify the exact PKC isoforms which contributed to the downregulatio n of GLP-1R or impaired post-receptor signaling pathways in rodent cardiomyocytes (H9C2 cells) cultured by high glucose. RESULTS: The cardioprotective effects of endogenous GLP-1 were impaired in diabetic mice after myocardial IRI and administration of exendin-4 had no significant effects in restoring cardiac function. GLP-1 receptor (GLP-1R) expression decreased in H9C2 cells cultured by high glucose and knockdown of PKCß partly restored GLP-1R expression. Overexpression of PKCδ induced by high glucose in H9C2 cells impaired GLP-1 post-receptor anti-apoptotic signaling pathways by inhibition of Akt phosphorylation. Knockdown of both PKCß and PKCδ significantly restored cardioprotective effects of GLP-1 in H9C2 cells cultured by high glucose. CONCLUSION: Our study found out a new mechanism of GLP-1 resistance that high glucose-induced overexpression of PKCß and PKCδ impaired cardioprotective effects of GLP-1 by downregulation of GLP-1R and inhibition of GLP-1 post-receptor anti-apoptotic signaling pathways, thus provided a new perspective in treating myocardial IRI in diabetic patients.

Preliminary evaluation of 18F­AlF­NOTA­MAL­Cys40­Exendin­4 in rodent heart after myocardial ischemia and reperfusion.

Glucagon­like peptide­1 (GLP­1) and its receptor (GLP­1R) exert cardioprotective effects after myocardial ischemia and reperfusion (MI/R) in animal models and human clinical trials. Receptor imaging with positron emission tomography (PET) provides a non­invasive method for monitoring GLP­1R expression. In the present study, a fluorine­18­labeled aluminum fluoride exendin­4 analog [18F­AlF conjugated with 1,4,7­triazacyclononanetriacetic acid (NOTA)­maleimide (MAL)­Cys40­exendin­4] was synthesized and evaluated in a rat MI/R model for GLP­1R imaging. NOTA­MAL­Cys40­exendin­4 was synthesized by coupling Cys40­exendin­4 with NOTA­MAL. NOTA­MAL­Cys40­exendin­4 was then conjugated with 18F­AlF to obtain 18F­AlF­NOTA­MAL­Cys40­exendin­4. The yield of 18F­AlF­NOTA­MAL­Cys40­exendin­4 was 18.5±3.4% (not decay corrected). The process was completed within ~30 min. In rat MI/R models, the tracer exhibited specific binding to GLP­1R and an appropriate signal­to­noise ratio. At 8 h post­MI/R, tracer uptake reached its peak [0.35±0.053% of injected dose (%ID)/g; n=6] in ischemic myocardium. Localized tracer uptake decreased 1 day (0.20±0.032 %ID/g; n=6) and 3 days (0.16±0.017 %ID/g; n=6) post­MI/R compared with 8 h post­MI/R, but still remained higher compared with sham­operated groups (0.06±0.012 %ID/g; n=6). Pre­injected unlabeled exendin­4 effectively blocked tracer accumulation (0.09±0.041 %ID/g; n=6). In conclusion, 18F­AlF­NOTA­MAL­Cys40­exendin­4 demonstrated favorable characteristics for GLP­1R imaging following MI/R. PET imaging using 18F­AlF­NOTA­MAL­Cys40­exendin­4 in rodent hearts after MI/R revealed a dynamic pattern of GLP­1R upregulation.

Sustained nicorandil administration reduces the infarct size in ST-segment elevation myocardial infarction patients with primary percutaneous coronary intervention.

OBJECTIVE: Currently, there is still no effective strategy to diminish the infarct size (IS) in patients with ST-segment elevation myocardial infarction (STEMI). According to a previous animal study, nicorandil treatment is a promising pharmaceutical treatment to limit the infarct area. In this study, we aim to investigate the effects of continual nicorandil administration on the IS and the clinical outcomes in patients with STEMI who underwent primary percutaneous coronary intervention (pPCI). METHODS: One hundred seventeen patients with STEMI and undergoing pPCI were randomly divided into the sustained nicorandil group (5 mg, three times daily) or the control group (only single nicorandil before PCI). The primary endpoint was the IS, evaluated by single-photon emission computed tomography (SPECT) 3 months after pPCI. RESULTS: Eighty-five patients completed the IS assessment via SPECT, and 99 participants were available for follow-up after 6 months. Finally, there was a statistical difference in the IS between the nicorandil and control groups {13% [interquartile range (IQR), 8-17] versus 16% [IQR, 12-20.3], p=0.027}. Additionally, we observed that maintained nicorandil administration significantly improved the left ventricular ejection fraction at 3 months and enhanced the activity tolerance (physical limitation and angina stability) at 6 months after PCI. CONCLUSION: Sustained nicorandil treatment reduced the IS and improved the clinical outcomes compared to the single nicorandil administration for patients with STEMI undergoing the pPCI procedure. Continuous cardioprotective therapy may be more beneficial for patients with STEMI.

Mst1 inhibits Sirt3 expression and contributes to diabetic cardiomyopathy through inhibiting Parkin-dependent mitophagy.

Mitochondrial dysfunction contributes to heart failure induced mortality in approximately 80% of diabetic patients. Mitophagy degrades defective mitochondria and maintains a healthy mitochondrial population, which is essential for cardiomyocyte survival in diabetic stress. Herein, we determined whether Mst1 regulated mitophagy and investigated the downstream signaling pathway in the development of diabetic cardiomyopathy (DCM). Mst1 deficiency promoted elimination of dysfunctional mitochondria in diabetic cardiomyopathy without affecting mitochondrial biogenesis. Enhanced mitophagy was observed in Mst1 interfering cardiomyocytes subjected to high glucose treatment using 3-Methyladenine and Chloroquine. Consistent with these results, in vivo and in vitro loss of function experiments indicated that Mst1 participated in the development of DCM by inhibiting Parkin-dependent mitophagy. Mst1 deficiency alleviated the detrimental phenotype of DCM. Interestingly, the protective effects of Mst1 knockout on DCM were compromised in diabetic Parkin-/- mice. Mechanistically, Mst1 knockdown significantly enhanced Parkin expression and translocation to the mitochondria, as evidenced by immunofluorescence study and Western blot analysis. Furthermore, Sirt3 deletion abolished the detrimental effects of Mst1 on DCM. Collectively, Mst1 inhibits Sirt3 expression thus participates in the development of DCM by inhibiting cardiomyocyte mitophagy. The mechanism is associated with Parkin inhibition.

Cardiac-specific Mst1 deficiency inhibits ROS-mediated JNK signalling to alleviate Ang II-induced cardiomyocyte apoptosis.

Apoptosis is associated with various myocardial diseases. Angiotensin II (Ang II) plays a central role in the pathogenesis of RAAS-triggered cardiac apoptosis. Our previous studies showed that mammalian Ste20-like kinase 1 (Mst1) aggravates cardiac dysfunction in cardiomyocyte under pathological conditions, but its role in Ang II-mediated cardiomyocyte apoptosis is not known. We addressed this in the present study by investigating whether cardiac-specific Mst1 knockout can alleviate Ang II-induced cardiomyocyte apoptosis along with the underlying mechanisms. In vitro and in vivo experiments showed that Ang II increased intracellular reactive oxygen species (ROS) production and cardiomyocyte apoptosis; these were reversed by administration of the ROS scavenger N-acetylcysteine and by Mst1 deficiency, which suppressed c-Jun N-terminal kinase (JNK) phosphorylation and downstream signaling. Interestingly, Mst1 knockout failed to alleviate Ang II-induced phosphorylation of extracellular signal-regulated kinase 1/2, and inactivated apoptosis signal-regulating kinase1 (ASK1) by promoting its association with thioredoxin (Trx), which reversed the Ang II-induced activation of the ASK1-JNK pathway and suppressed Ang II-induced cardiomyocyte apoptosis. Thus, cardiac-specific Mst1 knockout inhibits ROS-mediated JNK signalling to block Ang II-induced cardiomyocyte apoptosis, suggesting Mst1 as a potential therapeutic target for treatment of RAAS-activated heart failure.

Association of serum adropin with the presence of atrial fibrillation and atrial remodeling.

OBJECTIVE: Adropin, a newly identified regulatory protein encoded by Enho gene, suppressed tumor necrosis factor α-induced THP1 monocyte adhesion to human umbilical vein endothelial cells. In addition, inflammation is demonstrated to be involved in the mechanism of atrial fibrillation (AF). Atrial remodeling is correlated with the persistence and progression of AF. Adropin is hypothesized to correlated with AF and atrial remodeling. This study aims to determine the correlation of serum adropin and the presence of AF and remodeling. METHODS: This study consisted of 344 AF patients and 210 healthy controls. AF patients were then divided into three subgroups of paroxysmal AF, persistent AF, and permanent AF. Serum adropin concentrations were examined using enzyme-linked immunosorbent assay method. Left atrial diameter (LAD) was measured to evaluate atrial remodeling. RESULTS: Decreased serum adropin concentrations were found in AF patients compared with healthy controls. Logistic regression analysis confirmed that serum adropin was inversely associated with the presence of AF (OR 0.218, 95% CI 0.15-0.316; P < 0.001). Permanent AF patients had significantly reduced serum adropin concentrations compared with persistent and paroxysmal AF patients. There were decreased serum adropin concentrations in persistent AF group than those in paroxysmal AF group. Simple linear regression analyses showed that serum adropin in AF patients were negatively correlated with BMI, SBP, and LAD. Multiple stepwise regression analysis showed that LAD remained to be inversely associated with serum adropin (ß = 0.2, P = 0.010). CONCLUSION: Serum adropin concentrations are inversely correlated with the presence of AF and atrial remodeling.

Simvastatin Protects Heart from Pressure Overload Injury by Inhibiting Excessive Autophagy.

Cardiac hypertrophy is an independent predictor of cardiovascular morbidity and mortality. To identify the mechanisms by which simvastatin inhibits cardiac hypertrophy induced by pressure overload, we determined effects of simvastatin on 14-3-3 protein expression and autophagic activity. Simvastatin was administered intragastrically to Sprague-Dawley (SD) rats before abdominal aortic banding (AAB). Neonatal rat cardiomyocytes (NRCs) were treated with simvastatin before angiotensin II (AngII) stimulation. 14-3-3, LC3, and p62 protein levels were determined by western blot. Autophagy was also measured by the double-labeled red fluorescent protein-green fluorescent protein autophagy reporter system. Simvastatin alleviated excessive autophagy, characterized by a high LC3II/LC3I ratio and low level of p62, and blunted cardiac hypertrophy while increasing 14-3-3 protein expression in rats that had undergone AAB. In addition, it increased 14-3-3 expression and inhibited excessive autophagy in NRCs exposed to AngII. Our study demonstrated that simvastatin may inhibit excessive autophagy, increase 14-3-3 expression, and finally exert beneficial effects on cardioprotection against pressure overload.