SOD2 deficiency in cardiomyocytes defines defective mitochondrial bioenergetics as a cause of lethal dilated cardiomyopathy

Mitochondrial Structure and Function in Human Heart Failure

Despite clinical and scientific advancements, heart failure is the major cause of morbidity and mortality worldwide. Both mitochondrial dysfunction and inflammation contribute to the development and progression of heart failure. Although inflammation is crucial to reparative healing following acute cardiomyocyte injury, chronic inflammation damages the heart, impairs function, and decreases cardiac output. Mitochondria, which comprise one third of cardiomyocyte volume, may prove a potential therapeutic target for heart failure. Known primarily for energy production, mitochondria are also involved in other processes including calcium homeostasis and the regulation of cellular apoptosis. Mitochondrial function is closely related to morphology, which alters through mitochondrial dynamics, thus ensuring that the energy needs of the cell are met. However, in heart failure, changes in substrate use lead to mitochondrial dysfunction and impaired myocyte function. This review discusses mitochondrial and cristae dynamics, including the role of the mitochondria contact site and cristae organizing system complex in mitochondrial ultrastructure changes. Additionally, this review covers the role of mitochondria-endoplasmic reticulum contact sites, mitochondrial communication via nanotunnels, and altered metabolite production during heart failure. We highlight these often-neglected factors and promising clinical mitochondrial targets for heart failure.

Free radicals and oxidative stress: Mechanisms and therapeutic targets: Review article

BACKGROUND

Free radicals are small extremely reactive species that have unpaired electrons. Free radicals include subgroups of reactive species, which are all a product of regular cellular metabolism. Oxidative stress happens when the free radicals production exceeds the capacity of the antioxidant system in the body's cells.

OBJECTIVE

The current review clarifies the prospective role of antioxidants in the inhibition and healing of diseases.

METHODS

Information on oxidative stress, free radicals, reactive oxidant species, and natural and synthetic antioxidants was obtained by searching electronic databases like PubMed, Web of Science, and Science Direct, with articles published between 1987 and 2023 being included in this review.

RESULTS

Free radicals exhibit a dual role in living systems. They are toxic byproducts of aerobic metabolism that lead to oxidative injury and tissue disorders and act as signals to activate appropriate stress responses. Endogenous and exogenous sources of reactive oxygen species are discussed in this review. Oxidative stress is a component of numerous diseases, including diabetes mellitus, atherosclerosis, cardiovascular disease, Alzheimer's disease, Parkinson's disease, and cancer. Although various small molecules assessed as antioxidants have shown therapeutic prospects in preclinical studies, clinical trial outcomes have been inadequate. Understanding the mechanisms through which antioxidants act, where, and when they are active may reveal a rational approach that leads to more tremendous pharmacological success. This review studies the associations between oxidative stress, redox signaling, and disease, the mechanisms through which oxidative stress can donate to pathology, the antioxidant defenses, the limits of their effectiveness, and antioxidant defenses that can be increased through physiological signaling, dietary constituents, and probable pharmaceutical interference. Prospective clinical applications of enzyme mimics and current progress in metal- and non-metal-based materials with enzyme-like activities and protection against chronic diseases have been discussed.

CONCLUSION

This review discussed oxidative stress as one of the main causes of illnesses, as well as antioxidant systems and their defense mechanisms that can be useful in inhibiting these diseases. Thus, the positive and deleterious effects of antioxidant molecules used to lessen oxidative stress in numerous human diseases are discussed. The optimal level of vitamins and minerals is the amount that achieves the best feed benefit, best growth rate, and health, including immune efficiency, and provides sufficient amounts to the body.

Superoxide dismutase 2 scavenges ROS to promote osteogenic differentiation of human periodontal ligament stem cells by regulating Smad3 in alveolar bone-defective rats

BACKGROUND

Osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) is an essential event in alveolar bone regeneration. Oxidative stress may be the main inhibiting factor of hPDLSC osteogenesis. Superoxide dismutase 2 (SOD2) is a key antioxidant enzyme, but its effect on hPDLSC osteogenic differentiation is unclear.

METHODS

Several surface markers were detected by flow cytometry, and the differentiation potential of hPDLSCs was validated by alkaline phosphatase (ALP), Alizarin Red S, and Oil Red O staining. Osteogenic indicators of hPDLSCs were detected by real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and ALP staining. Furthermore, alveolar bone defect rat models were analyzed through micro-CT, hematoxylin and eosin, and Masson staining. The intracellular reactive oxygen species (ROS) level was evaluated by a ROS assay kit. Finally, the expression of SOD2, Smad3, and p-Smad3 in hPDLSCs was detected by RT-qPCR and Western blotting (WB).

RESULTS

SOD2 positively regulated the gene and protein expressions of ALP, BMP6, and RUNX2 in hPDLSCs (p < 0.05). Ideal bone formation and continuous cortical bone were obtained by transplanting LV-SOD2 hPDLSCs (lentivirus vector for overexpressing SOD2 in hPDLSCs) in vivo. Exogenous H2O2 downregulated osteogenic indicators (ALP, BMP6, RUNX2) in hPDLSCs (p < 0.05); this was reversed by overexpression of SOD2. WB results showed that the Smad3 and p-Smad3 signaling pathways participated in the osteogenic process of SOD2 in hPDLSCs.

CONCLUSION

SOD2 positively regulated hPDLSC osteogenic differentiation in vitro and in vivo. Mechanistically, SOD2 promotes hPDLSC osteogenic differentiation by regulating the phosphorylation of Smad3 to scavenge ROS. This work provides a theoretical basis for the treatment of alveolar bone regeneration.

Bioinformatics identifies key genes and potential drugs for energy metabolism disorders in heart failure with dilated cardiomyopathy

Background: Dysfunction in myocardial energy metabolism plays a vital role in the pathological process of Dilated Cardiomyopathy (DCM). However, the precise mechanisms remain unclear. This study aims to investigate the key molecular mechanisms of energy metabolism and potential therapeutic agents in the progression of dilated cardiomyopathy with heart failure. Methods: Gene expression profiles and clinical data for patients with dilated cardiomyopathy complicated by heart failure, as well as healthy controls, were sourced from the Gene Expression Omnibus (GEO) database. Gene sets associated with energy metabolism were downloaded from the Molecular Signatures Database (MSigDB) for subsequent analysis. Weighted Gene Co-expression Network Analysis (WGCNA) and differential expression analysis were employed to identify key modules and genes related to heart failure. Potential biological mechanisms were investigated through Gene Set Enrichment Analysis (GSEA), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and the construction of a competing endogenous RNA (ceRNA) network. Molecular docking simulations were then conducted to explore the binding affinity and conformation of potential therapeutic drugs with hub genes. Results: Analysis of the left ventricular tissue expression profiles revealed that, compared to healthy controls, patients with dilated cardiomyopathy exhibited 234 differentially expressed genes and 2 genes related to myocardial energy metabolism. Additionally, Benzoylaconine may serve as a potential therapeutic agent for the treatment of dilated cardiomyopathy. Conclusion: The study findings highlight the crucial role of myocardial energy metabolism in the progression of Dilated Cardiomyopathy. Notably, Benzoylaconine emerges as a potential candidate for treating Dilated Cardiomyopathy, potentially exerting its therapeutic effects by targeted modulation of myocardial energy metabolism through NRK and NT5.

LncRNA CHKB-DT Downregulation Enhances Dilated Cardiomyopathy Through ALDH2

BACKGROUND

Human cardiac long noncoding RNA (lncRNA) profiles in patients with dilated cardiomyopathy (DCM) were previously analyzed, and the long noncoding RNA CHKB (choline kinase beta) divergent transcript (CHKB-DT) levels were found to be mostly downregulated in the heart. In this study, the function of CHKB-DT in DCM was determined.

METHODS

Long noncoding RNA expression levels in the human heart tissues were measured via quantitative reverse transcription-polymerase chain reaction and in situ hybridization assays. A CHKB-DT heterozygous or homozygous knockout mouse model was generated using the clustered regularly interspaced palindromic repeat (CRISPR)/CRISPR-associated protein 9 system, and the adeno-associated virus with a cardiac-specific promoter was used to deliver the RNA in vivo. Sarcomere shortening was performed to assess the primary cardiomyocyte contractility. The Seahorse XF cell mitochondrial stress test was performed to determine the energy metabolism and ATP production. Furthermore, the underlying mechanisms were explored using quantitative proteomics, ribosome profiling, RNA antisense purification assays, mass spectrometry, RNA pull-down, luciferase assay, RNA-fluorescence in situ hybridization, and Western blotting.

RESULTS

CHKB-DT levels were remarkably decreased in patients with DCM and mice with transverse aortic constriction-induced heart failure. Heterozygous knockout of CHKB-DT in cardiomyocytes caused cardiac dilation and dysfunction and reduced the contractility of primary cardiomyocytes. Moreover, CHKB-DT heterozygous knockout impaired mitochondrial function and decreased ATP production as well as cardiac energy metabolism. Mechanistically, ALDH2 (aldehyde dehydrogenase 2) was a direct target of CHKB-DT. CHKB-DT physically interacted with the mRNA of ALDH2 and fused in sarcoma (FUS) through the GGUG motif. CHKB-DT knockdown aggravated ALDH2 mRNA degradation and 4-HNE (4-hydroxy-2-nonenal) production, whereas overexpression of CHKB-DT reversed these molecular changes. Furthermore, restoring ALDH2 expression in CHKB-DT+/- mice alleviated cardiac dilation and dysfunction.

CONCLUSIONS

CHKB-DT is significantly downregulated in DCM. CHKB-DT acts as an energy metabolism-associated long noncoding RNA and represents a promising therapeutic target against DCM.

Prostaglandin E2 affects mitochondrial function in adult mouse cardiomyocytes and hearts

Prostaglandin E2 (PGE2) signals differently through 4 receptor subtypes (EP1-EP4) to elicit diverse physiologic/pathologic effects. We previously reported that PGE2 via its EP3 receptor reduces cardiac contractility and male mice with cardiomyocyte-specific deletion of the EP4 receptor (EP4 KO) develop dilated cardiomyopathy. The aim of this study was to identify pathways responsible for this phenotype. We performed ingenuity pathway analysis (IPA) and found that genes differentiating WT mice and EP4 KO mice were significantly overrepresented in mitochondrial (adj. p value = 6.28 × 10-26) and oxidative phosphorylation (adj. p value = 1.58 × 10-27) pathways. Electron microscopy from the EP4 KO hearts show substantial mitochondrial disarray and disordered cristae. Not surprisingly, isolated adult mouse cardiomyocytes (AVM) from these mice have reduced ATP levels compared to their WT littermates and reduced expression of key genes involved in the electron transport chain (ETC) in older mice. Moreover, treatment of AVM from C57Bl/6 mice with PGE2 or the EP3 agonist sulprostone resulted in changes of various genes involved in the ETC, measured by the Mitochondrial Energy Metabolism RT2-profiler assay. Lastly, the EP4 KO mice have reduced expression of superoxide dismuatse-2 (SOD2), whereas treatment of AVM with PGE2 or sulprostone increase superoxide production, suggesting increased oxidative stress levels in these EP4 KO mice. Altogether the current study supports the premise that PGE2 acting via its EP4 receptor is protective, while signaling through its other receptors, likely EP3, is deleterious.

miR-20a-5p targeting mfn2-mediated mitochondria-lipid droplet contacts regulated differential changes in hepatic lipid metabolism induced by two Mn sources in yellow catfish

Understanding the hazards of different forms of metal elements provided innovative insights into their toxicity and environmental risk assessment. To date, few studies had been conducted to investigate the differential effects and mechanisms of MnO2 NPs and MnSO4, two widely distributed environmental pollutants, on hepatic toxicity and lipid metabolism since lipid metabolism-relevant parameters were broadly used as biomarkers for risk assessment of hazardous contaminants. Thus, using yellow catfish Pelteobagrus fulvidraco, an ecologically and economically important freshwater fish as the model, the present study investigated the differential effects and mechanisms of MnO2 NPs and MnSO4 influencing hepatic lipid metabolism. Compared to MnSO4, MnO2 NPs increased hepatic Mn content, induced lipotoxicity, up-regulated the mRNA expression of lipogenic genes, increased peridroplet mitochondrial (PDM) contents, intensified the contact between mitochondria and lipid droplets (LDs), and downregulated miR-20a-5p abundance. Importantly, miR-20a-5p targeted mfn2, which mediated the contact between mitochondria and LDs and influenced changes in lipid metabolism induced by MnO2 NPs. Mechanistically, the direct Mfn2-Plin2 binding and Mfn2 GTPase activity promoted the MnO2 NPs-induced interactions between mitochondria and LDs, which in turn influenced MnO2 NPs-induced changes in hepatic lipid metabolism. For the first time, our findings indicated the significant differences between the changes in body metabolism induced by nanoparticles and inorganic elements, which helped to illuminate different mechanisms governing the responses of aquatic vertebrates to hazardous metal pollutants (MnO2 NPs and MnSO4).

Dose-Dependent Effect of Mitochondrial Superoxide Dismutase Gene Overexpression on Radioresistance of HEK293T Cells

Over the last two decades, a multitude of gain-of-function studies have been conducted on genes that encode antioxidative enzymes, including one of the key enzymes, manganese superoxide dismutase (SOD2). The results of such studies are often contradictory, as they strongly depend on many factors, such as the gene overexpression level. In this study, the effect of altering the ectopic expression level of major transcript variants of the SOD2 gene on the radioresistance of HEK293T cells was investigated using CRISPRa technology. A significant increase in cell viability in comparison with the transfection control was detected in cells with moderate SOD2 overexpression after irradiation at 2 Gy, but not at 3 or 5 Gy. A further increase in the level of SOD2 ectopic expression up to 22.5-fold resulted in increased cell viability detectable only after irradiation at 5 Gy. Furthermore, a 15-20-fold increase in SOD2 expression raised the clonogenic survival of cells after irradiation at 5 Gy. Simultaneous overexpression of genes encoding SOD2 and Catalase (CAT) enhanced clonogenic cell survival after irradiation more effectively than separate overexpression of both. In conjunction with the literature data on the suppression of the procarcinogenic effects of superoxide dismutase overexpression by ectopic expression of CAT, the data presented here suggest the potential efficacy of simultaneous overexpression of SOD2 and CAT to reduce oxidative stress occurring in various pathological processes. Moreover, these results illustrate the importance of selecting the degree of SOD2 overexpression to obtain a protective effect.

Induced differentiation of primordial germ cell like cells from SOX9+ porcine skin derived stem cells

Understanding the mechanisms behind porcine primordial germ cell like cells (pPGCLCs) development, differentiation, and gametogenesis is crucial in the treatment of infertility. In this study, SOX9+ skin derived stem cells (SOX9+ SDSCs) were isolated from fetal porcine skin and a high-purity SOX9+ SDSCs population was obtained. The SOX9+ SDSCs were induced to transdifferentiate into PGCLCs during 8 days of cultured. The results of RNA-seq, western blot and immunofluorescence staining verified SDSCs have the potential to transdifferentiate into PGCLCs from aspects of transcription factor activation, germ layer differentiation, energy metabolism, and epigenetic changes. Both adherent and suspended cells were collected. The adherent cells were found to be very similar to early porcine primordial germ cells (pPGCs). The suspended cells resembled late stage pPGCs and had a potential to enter meiotic process. This SDSCs culture-induced in vitro model is expected to provide suitable donor cells for stem cell transplantation in the future.

Age-Related Shift in Cardiac and Metabolic Phenotyping Linked to Inflammatory Cytokines and Antioxidant Status in Mice

Age-related alterations in cardiac function, metabolic, inflammatory and antioxidant profiles are associated with an increased risk of cardiovascular mortality and morbidity. Here, we examined cardiac and metabolic phenotypes in relation to inflammatory status and antioxidant capacity in young, middle-aged and old mice. Real-time reverse transcription-polymerase chain reactions were performed on myocardium and immunoassays on plasma. Left ventricular (LV) structure and function were assessed by echocardiography using high-frequency ultrasound. Middle-aged mice exhibited an altered metabolic profile and antioxidant capacity compared to young mice, whereas myocardial expression of inflammatory factors (TNFα, IL1β, IL6 and IL10) remained unchanged. In contrast, old mice exhibited increased expression of inflammatory cytokines and plasma levels of resistin compared to young and middle-aged mice (p < 0.05). The pro-inflammatory signature of aged hearts was associated with alterations in glutathione redox homeostasis and elevated contents of 4-hydroxynonenal (4-HNE), a marker of lipid peroxidation and oxidative stress. Furthermore, echocardiographic parameters of LV systolic and diastolic functions were significantly altered in old mice compared to young mice. Taken together, these findings suggest age-related shifts in cardiac phenotype encompass the spectrum of metabo-inflammatory abnormalities and altered redox homeostasis.

Mitochondrial Cristae Morphology Reflecting Metabolism, Superoxide Formation, Redox Homeostasis, and Pathology

Significance: Mitochondrial (mt) reticulum network in the cell possesses amazing ultramorphology of parallel lamellar cristae, formed by the invaginated inner mitochondrial membrane. Its non-invaginated part, the inner boundary membrane (IBM) forms a cylindrical sandwich with the outer mitochondrial membrane (OMM). Crista membranes (CMs) meet IBM at crista junctions (CJs) of mt cristae organizing system (MICOS) complexes connected to OMM sorting and assembly machinery (SAM). Cristae dimensions, shape, and CJs have characteristic patterns for different metabolic regimes, physiological and pathological situations. Recent Advances: Cristae-shaping proteins were characterized, namely rows of ATP-synthase dimers forming the crista lamella edges, MICOS subunits, optic atrophy 1 (OPA1) isoforms and mitochondrial genome maintenance 1 (MGM1) filaments, prohibitins, and others. Detailed cristae ultramorphology changes were imaged by focused-ion beam/scanning electron microscopy. Dynamics of crista lamellae and mobile CJs were demonstrated by nanoscopy in living cells. With tBID-induced apoptosis a single entirely fused cristae reticulum was observed in a mitochondrial spheroid. Critical Issues: The mobility and composition of MICOS, OPA1, and ATP-synthase dimeric rows regulated by post-translational modifications might be exclusively responsible for cristae morphology changes, but ion fluxes across CM and resulting osmotic forces might be also involved. Inevitably, cristae ultramorphology should reflect also mitochondrial redox homeostasis, but details are unknown. Disordered cristae typically reflect higher superoxide formation. Future Directions: To link redox homeostasis to cristae ultramorphology and define markers, recent progress will help in uncovering mechanisms involved in proton-coupled electron transfer via the respiratory chain and in regulation of cristae architecture, leading to structural determination of superoxide formation sites and cristae ultramorphology changes in diseases. Antioxid. Redox Signal. 39, 635-683.

The antidepressant drugs vortioxetine and duloxetine differentially and sex-dependently affect animal well-being, cognitive performance, cardiac redox status and histology in a model of osteoarthritis

Osteoarthritis represents a leading cause of disability with limited treatment options. Furthermore, it is frequently accompanied by cardiovascular and cognitive disorders, which can be exacerbated by osteoarthritis or drugs used for its treatment. Here, we examined the behavioral and cardiac effects of the novel antidepressant vortioxetine in an osteoarthritis model, and compared them to duloxetine (an established osteoarthritis treatment). Osteoarthritis was induced in male and female rats with an intraarticular sodium-monoiodoacetate injection. Antidepressants were orally administered for 28 days following induction. During this period the acetone, burrowing and novel-object-recognition tests (NORT) were used to assess the effects of antidepressants on pain hypersensitivity (cold allodynia), animal well-being and cognitive performance, respectively. Following behavioral experiments, heart muscles were collected for assessment of redox status/histology. Antidepressant treatment dose-dependently reduced cold allodynia in rats with osteoarthritis. Duloxetine (but not vortioxetine) depressed burrowing behavior in osteoarthritic rats in a dose-related manner. Osteoarthritis induction reduced cognitive performance in NORT, which was dose-dependently alleviated by vortioxetine (duloxetine improved performance only in female rats). Furthermore, duloxetine (but not vortioxetine) increased oxidative stress parameters in the heart muscles of female (but not male) rats and induced histological changes in cardiomyocytes indicative of oxidative damage. Vortioxetine displayed comparable efficacy to duloxetine in reducing pain hypersensitivity. Furthermore, vortioxetine (unlike duloxetine) dose-dependently improved cognitive performance and had no adverse effect on burrowing behavior (animal surrogate of well-being) and cardiac redox status/histology. Our results indicate that vortioxetine could be a potential osteoarthritis treatment (with better characteristics compared to duloxetine).

Mitochondrial heterogeneity in diseases

As key organelles involved in cellular metabolism, mitochondria frequently undergo adaptive changes in morphology, components and functions in response to various environmental stresses and cellular demands. Previous studies of mitochondria research have gradually evolved, from focusing on morphological change analysis to systematic multiomics, thereby revealing the mitochondrial variation between cells or within the mitochondrial population within a single cell. The phenomenon of mitochondrial variation features is defined as mitochondrial heterogeneity. Moreover, mitochondrial heterogeneity has been reported to influence a variety of physiological processes, including tissue homeostasis, tissue repair, immunoregulation, and tumor progression. Here, we comprehensively review the mitochondrial heterogeneity in different tissues under pathological states, involving variant features of mitochondrial DNA, RNA, protein and lipid components. Then, the mechanisms that contribute to mitochondrial heterogeneity are also summarized, such as the mutation of the mitochondrial genome and the import of mitochondrial proteins that result in the heterogeneity of mitochondrial DNA and protein components. Additionally, multiple perspectives are investigated to better comprehend the mysteries of mitochondrial heterogeneity between cells. Finally, we summarize the prospective mitochondrial heterogeneity-targeting therapies in terms of alleviating mitochondrial oxidative damage, reducing mitochondrial carbon stress and enhancing mitochondrial biogenesis to relieve various pathological conditions. The possibility of recent technological advances in targeted mitochondrial gene editing is also discussed.

Sirtuin 3 controls cardiac energetics and protects against oxidative stress in electromagnetic radiation-induced cardiomyopathy

Electromagnetic radiation can cause injuries to both the structures and functions of the heart. No therapy is currently available to inhibit these untoward effects. Mitochondrial energetic damage and oxidative stress are drivers of electromagnetic radiation-induced cardiomyopathy (eRIC); however, the pathways that mediate these events are poorly defined. Sirtuin 3 (SIRT3) has been emerged as a key target for maintaining mitochondrial redox potential and metabolism, but its role in eRIC remains unknown. Here, Sirt3-KO mice and cardiac-specific SIRT3 transgenic mice were subjected to the investigation of eRIC. We found that Sirt3 protein expression level was down-regulated in eRIC mice model. Sirt3-KO markedly exaggerated decreases in cardiac energetics and increases in oxidative stress in microwave irradiation (MWI)-stressed mice. Conversely, cardiac-specific SIRT3 overexpression protected the hearts from these effects and rescued cardiac malfunction. Mechanistically, Sirt3 maintained AMP-activated protein kinase (AMPK) signaling pathway in MWI-stressed hearts in vivo. In conclusion, electromagnetic radiation repressed SIRT3 expression and disturbed cardiac energetics and redox homeostasis. The increased SIRT3 expression and AMPK activation in vivo prevented eRIC, indicating that SIRT3 will be a potential therapeutic target for curative interventions in eRIC.

Targeting oxidative stress as a preventive and therapeutic approach for cardiovascular disease

Cardiovascular diseases (CVDs) continue to exert a significant impact on global mortality rates, encompassing conditions like pulmonary arterial hypertension (PAH), atherosclerosis (AS), and myocardial infarction (MI). Oxidative stress (OS) plays a crucial role in the pathogenesis and advancement of CVDs, highlighting its significance as a contributing factor. Maintaining an equilibrium between reactive oxygen species (ROS) and antioxidant systems not only aids in mitigating oxidative stress but also confers protective benefits on cardiac health. Herbal monomers can inhibit OS in CVDs by activating multiple signaling pathways, such as increasing the activity of endogenous antioxidant systems and decreasing the level of ROS expression. Given the actions of herbal monomers to significantly protect the normal function of the heart and reduce the damage caused by OS to the organism. Hence, it is imperative to recognize the significance of herbal monomers as prospective therapeutic interventions for mitigating oxidative damage in CVDs. This paper aims to comprehensively review the origins and mechanisms underlying OS, elucidate the intricate association between CVDs and OS, and explore the therapeutic potential of antioxidant treatment utilizing herbal monomers. Furthermore, particular emphasis will be placed on examining the cardioprotective effects of herbal monomers by evaluating their impact on cardiac signaling pathways subsequent to treatment.

COX5A Alleviates Doxorubicin-Induced Cardiotoxicity by Suppressing Oxidative Stress, Mitochondrial Dysfunction and Cardiomyocyte Apoptosis

Doxorubicin (DOX) as a chemotherapeutic agent can cause mitochondrial dysfunction and heart failure. COX5A has been described as an important regulator of mitochondrial energy metabolism. We investigate the roles of COX5A in DOX-induced cardiomyopathy and explore the underlying mechanisms. C57BL/6J mice and H9c2 cardiomyoblasts were treated with DOX, and the COX5A expression was assessed. An adeno-associated virus serum type 9 (AAV9) and lenti-virus system were used to upregulate COX5A expression. Echocardiographic parameters, morphological and histological analyses, transmission electron microscope and immunofluorescence assays were used to assess cardiac and mitochondrial function. In a human study, we found that cardiac COX5A expression was dramatically decreased in patients with end-stage dilated cardiomyopathy (DCM) compared to the control group. COX5A was significantly downregulated following DOX stimulation in the heart of mice and H9c2 cells. Reduced cardiac function, decreased myocardium glucose uptake, mitochondrial morphology disturbance, reduced activity of mitochondrial cytochrome c oxidase (COX) and lowered ATP content were detected after DOX stimulation in mice, which could be significantly improved by overexpression of COX5A. Overexpression of COX5A effectively protected against DOX-induced oxidative stress, mitochondrial dysfunction and cardiomyocyte apoptosis in vivo and in vitro. Mechanistically, the phosphorylation of Akt (Thr308) and Akt (Ser473) were also decreased following DOX treatment, which could be reserved by the upregulation of COX5A. Furthermore, PI3K inhibitors abrogated the protection effects of COX5A against DOX-induced cardiotoxicity in H9c2 cells. Thus, we identified that PI3K/Akt signaling was responsible for the COX5A-mediated protective role in DOX-induced cardiomyopathy. These results demonstrated the protective effect of COX5A in mitochondrial dysfunction, oxidative stress, and cardiomyocyte apoptosis, providing a potential therapeutic target in DOX-induced cardiomyopathy.

Linagliptin exacerbates heart failure due to energy deficiency via downregulation of glucose utilization and absorption in a mouse model

Use of dipeptidyl peptidase-4 (DPP4) inhibitor in some clinical trials might have caused heart failure (HF), leading to increased hospitalizations. The aim of the present study was to determine whether linagliptin has any effect on chronic dilated HF, and its underlying mechanisms. Physiologic and pathologic studies were conducted on heart/muscle-specific manganese superoxide dismutase-deficient mice, which exhibited dilated cardiomyopathy, and were randomized to receive a low dose (1 mg/kg, HF-L group) or high dose (10 mg/kg, HF-H group) mixed with food, or normal food (HF group), for 8 weeks. Linagliptin increased mortality and heart/body weight ratio in mice with HF. Cardiac contractility and fibrosis worsened, whereas hepatic glycogen content and individual carbohydrate consumption decreased significantly in the HF-H group, when compared with the HF control group. Therefore, we performed a complementary experiment by supplementing glucose to the mice treated with high-dose linagliptin (HF-HG group). Adequate glucose supplementation reduced heart/body weight ratio and cardiac fibrosis, and improved cardiac contractility, without changing mortality. Following oral administration of 13C glucose, the respiratory 13C decreased in the HF-H and HF-HG groups, when compared with that in the HF group; the fecal 13C increased, suggesting that linagliptin inhibited glucose absorbance in the intestine. In addition, the expression of GLUT2, a glucose transporter was downregulated in the small intestine. Linagliptin treatment exacerbated HF, which increased mortality, cardiac function, and fibrosis. DPP4 inhibitors might boost cardiac cachexia and exacerbate HF, at least in part, through the modification of glucose utilization and absorption.

Integrative multi-omics deciphers the spatial characteristics of host-gut microbiota interactions in Crohn's disease

Dysregulated host-microbial interactions play critical roles in initiation and perpetuation of gut inflammation in Crohn's disease (CD). However, the spatial distribution and interaction network across the intestine and its accessory tissues are still elusive. Here, we profile the host proteins and tissue microbes in 540 samples from the intestinal mucosa, submucosa-muscularis-serosa, mesenteric adipose tissues, mesentery, and mesenteric lymph nodes of 30 CD patients and spatially decipher the host-microbial interactions. We observe aberrant antimicrobial immunity and metabolic processes across multi-tissues during CD and determine bacterial transmission along with altered microbial communities and ecological patterns. Moreover, we identify several candidate interaction pairs between host proteins and microbes associated with perpetuation of gut inflammation and bacterial transmigration across multi-tissues in CD. Signature alterations in host proteins (e.g., SAA2 and GOLM1) and microbes (e.g., Alistipes and Streptococcus) are further imprinted in serum and fecal samples as potential diagnostic biomarkers, thus providing a rationale for precision diagnosis.

Genetics of myocardial interstitial fibrosis in the human heart and association with disease

Myocardial interstitial fibrosis is associated with cardiovascular disease and adverse prognosis. Here, to investigate the biological pathways that underlie fibrosis in the human heart, we developed a machine learning model to measure native myocardial T1 time, a marker of myocardial fibrosis, in 41,505 UK Biobank participants who underwent cardiac magnetic resonance imaging. Greater T1 time was associated with diabetes mellitus, renal disease, aortic stenosis, cardiomyopathy, heart failure, atrial fibrillation, conduction disease and rheumatoid arthritis. Genome-wide association analysis identified 11 independent loci associated with T1 time. The identified loci implicated genes involved in glucose transport (SLC2A12), iron homeostasis (HFE, TMPRSS6), tissue repair (ADAMTSL1, VEGFC), oxidative stress (SOD2), cardiac hypertrophy (MYH7B) and calcium signaling (CAMK2D). Using a transforming growth factor β1-mediated cardiac fibroblast activation assay, we found that 9 of the 11 loci consisted of genes that exhibited temporal changes in expression or open chromatin conformation supporting their biological relevance to myofibroblast cell state acquisition. By harnessing machine learning to perform large-scale quantification of myocardial interstitial fibrosis using cardiac imaging, we validate associations between cardiac fibrosis and disease, and identify new biologically relevant pathways underlying fibrosis.

Characterization of cuproptosis identified immune microenvironment and prognosis in acute myeloid leukemia

BACKGROUND

Recent studies have reported that cuproptosis, a novel cell death pathway, strongly correlates with mitochondrial metabolism. In addition, the studies reported that cuproptosis plays a role in the development of several cancers and is regulated by protein lipoylation. During cuproptosis, copper binds to the lipoylated proteins and mediates cancer progression. However, the role of cuproptosis in acute myeloid leukemia (AML) patients is yet to be explored.

METHODS

This study curated seven cuproptosis-related-genes (CRGs): FDX1, DLAT, PDHB, PDHA1, DLD, LIAS, and LIPT1 to determine cuproptosis modification patterns and the CRGs signature in AML. The CIBERSORT and ssGSEA algorithms were utilized to evaluate the infiltration levels of different immune cell subtypes. A cuproptosis score system based on differentially expressed genes (DEGs) was constructed using the least absolute shrinkage and selection operator (LASSO) regression analysis. The developed cuproptosis score system was validated using two immunotherapy datasets, IMvigor210 and GSE78220.

RESULTS

Three distinct cuproptosis regulation patterns were identified using the Beat AML cohort. The results demonstrated that the three cuproptosis regulation patterns were correlated with various biological pathways and clinical outcomes. Tumor microenvironment (TME) characterization revealed that the identified cuproptosis regulation patterns were consistent with three immune profiles: immune-desert, immune-inflamed, and immune-excluded. The AML patients were grouped into low- and high-score groups based on the cuproptosis score system abstracted from 486 cuproptosis-related DEGs. Patients with lower cuproptosis scores were characterized by longer survival time and attenuated immune infiltration. It was found that lower cuproptosis scores were strongly correlated with lower somatic mutation frequency. Moreover, patients with lower cuproptosis scores presented more favorable immune responses and dual clinical benefits among external validation cohorts.

CONCLUSIONS

Cuproptosis phenotypes are significantly correlated with immune microenvironment complexity and variety. Cuprotopsis regulates the response of cancer cells to the immune system. Quantitatively assessing cuproptosis phenotypes in AML improves the understanding and knowledge regarding immune microenvironment characteristics and promotes the development of therapeutic interventions.

Prohibitin1 maintains mitochondrial quality in isoproterenol-induced cardiac hypertrophy in H9C2 cells

BACKGROUND INFORMATION

Various types of stress initially induce a state of cardiac hypertrophy (CH) in the heart. But, persistent escalation of cardiac stress leads to progression from an adaptive physiological to a maladaptive pathological state. So, elucidating molecular mechanisms that can attenuate CH is imperative in developing cardiac therapies. Previously, we showed that Prohibitin1 (PHB1) has a protective role in CH-induced oxidative stress. Nevertheless, it is unclear how PHB1, a mitochondrial protein, has a protective role in CH. Therefore, we hypothesized that PHB1 maintains mitochondrial quality in CH. To test this hypothesis, we used Isoproterenol (ISO) to induce CH in H9C2 cells overexpressing PHB1 and elucidated mitochondrial quality control pathways.

RESULTS

We found that overexpressing PHB1 attenuates ISO-induced CH and restores mitochondrial morphology in H9C2 cells. In addition, PHB1 blocks the pro-hypertrophic IGF1R/AKT pathway and restores the mitochondrial membrane polarization in ISO-treated cells. We observed that overexpressing PHB1 promotes mitochondrial biogenesis, improves mitochondrial respiratory capacity, and triggers mitophagy.

CONCLUSION

We conclude that PHB1 maintains mitochondrial quality in ISO-induced CH in H9C2 cells.

SIGNIFICANCE

Based on our results, we suggest that small molecules that induce PHB1 in cardiac cells may prove beneficial in developing cardiac therapies.

Introducing Intermolecular Interaction to Strengthen the Stability of MnSOD Dimer

Manganese superoxide dismutase from Staphylococcus equorum (MnSODSeq) maintains its activity upon treatments like a wide range of pH, addition of detergent and denaturing agent, exposure to ultraviolet light, and heating up to 50 °C. The enzyme dimer dissociates at 52-55 °C, while its monomer unfolds at 63-67 °C. MnSOD dimeric form is indispensable for the enzyme activity; therefore, strengthening the interactions between the monomers is the most preferred strategy to improve the enzyme stability. However, to date, modification of MnSODSeq at the dimer interface has been unfruitful despite excluding the inner and outer sphere regions that are important to the enzyme activity. Here, a new strategy was developed and K38R-A121E/Y double substitutions were proposed. These mutants displayed similar enzyme activity to the wild type. K38R-A121E dimer was thermally more stable and its monomer stability was similar to the wild type. The thermal stability of K38R-A121Y dimer was similar to the wild type but its monomer was thermally less stable. In addition, the structure of the previously reported L169W mutant was also elucidated. The L169W mutant structure showed that intramolecular modification can decrease flexibility of the MnSODSeq monomer and leads to a less stable enzyme with similar activity to the wild type. Thus, while the enzyme activity depends on arrangement of residues in the dimer interface, the stability appears to depend more on its monomeric architecture. Furthermore, in the L169W structure in complex with azide, which is a specific inhibitor for MnSOD, one of the azide molecules was present in the dimer interface region that previously has been identified to involve in the enzymatic reaction. Nevertheless, the present results show that an MnSODSeq mutant with better thermal stability has been obtained.

Proteome changes in a human retinal pigment epithelial cell line during oxidative stress and following antioxidant treatment

Age related macular degeneration (AMD) is the most common cause of blindness in the elderly. Oxidative stress contributes to retinal pigment epithelium (RPE) dysfunction and cell death thereby leading to AMD. Using improved RPE cell model systems, such as human telomerase transcriptase-overexpressing (hTERT) RPE cells (hTERT-RPE), pathophysiological changes in RPE during oxidative stress can be better understood. Using this model system, we identified changes in the expression of proteins involved in the cellular antioxidant responses after induction of oxidative stress. Some antioxidants such as vitamin E (tocopherols and tocotrienols) are powerful antioxidants that can reduce oxidative damage in cells. Alpha-tocopherol (α-Toc or αT) and gamma-tocopherol (γ-Toc or γT) are well-studied tocopherols, but signaling mechanisms underlying their respective cytoprotective properties may be distinct. Here, we determined what effect oxidative stress, induced by extracellularly applied tBHP in the presence and absence of αT and/or γT, has on the expression of antioxidant proteins and related signaling networks. Using proteomics approaches, we identified differential protein expression in cellular antioxidant response pathways during oxidative stress and after tocopherol treatment. We identified three groups of proteins based on biochemical function: glutathione metabolism/transfer, peroxidases and redox-sensitive proteins involved in cytoprotective signaling. We found that oxidative stress and tocopherol treatment resulted in unique changes in these three groups of antioxidant proteins indicate that αT and γT independently and by themselves can induce the expression of antioxidant proteins in RPE cells. These results provide novel rationales for potential therapeutic strategies to protect RPE cells from oxidative stress.

Deciphering the disturbance mechanism of BaP on the symbiosis of Montipora digitata via 4D-Proteomics approach

The coral holobiont is mainly composed of coral polyps, zooxanthellae, and coral symbiotic microorganisms, which form the basis of coral reef ecosystems. In recent years, the severe degradation of coral reefs caused by climate warming and environmental pollution has aroused widespread concern. Benzo(a)pyrene (BaP) is a widely distributed pollutant in the environment. However, the underlying mechanisms of coral symbiosis destruction due to the stress of BaP are not well understood. In this study, diaPASEF proteomics and 16S rRNA amplicon pyrosequencing technology were used to reveal the effects of 50 μg/L BaP on Montipora digitate. Data analysis was performed from the perspective of the main symbionts of M. digitata (coral polyps, zooxanthellae, and coral symbiotic microorganisms). The results showed that BaP impaired cellular antioxidant capacity by disrupting the GSH/GSSG cycle, and sustained stress causes severe impairment of energy metabolism and protein degradation in coral polyps. In zooxanthellae, BaP downregulated the protein expression of SOD2 and mtHSP70, which then resulted in oxidative free radical accumulation and apoptosis. For coral symbiotic microorganisms, BaP altered the community structure of microorganisms and decreased immunity. Coral symbiotic microorganisms adapted to the stress of BaP by adjusting energy metabolism and enhancing extracellular electron transfer. BaP adversely affected the three main symbionts of M. digitata via different mechanisms. Decreased antioxidant capacity is a common cause of damages to coral polyps and zooxanthellae, whereas coral symbiotic microorganisms are able to appropriately adapt to oxidative stress. This study assessed the effects of BaP on corals from a symbiotic perspective, which is more comprehensive and reliable. At the same time, data from the study supports new directions for coral research and coral reef protection.

Alteration of Cellular Energy Metabolism through LPAR2-Axin2 Axis in Gastric Cancer

Lysophosphatidic acid (LPA), a multifunctional endogenous phospholipid, plays a vital role in cellular homeostasis and the malignant behavior of cancer cells through G-protein-coupled receptors. However, the role of LPA in β-catenin-mediated gastric cancer is unknown. Here, we have noted the high expression of LPAR2 in human gastric cancer tissues, and that LPA treatment significantly increased the proliferation, migration, and invasion of human gastric cancer cells. Results from our biochemical experiments showed that an LPA exposure increased the expression of β-catenin and its nuclear localization, increased the phosphorylation of glycogen synthase kinase 3β (GSK-3β), decreased the expression of Axin2, and increased the expression of the target genes of the β-catenin signaling pathway. The LPA2 receptor (LPAR2) antagonist significantly reduced the LPA-induced nuclear localization of β-catenin, the primary signaling event. The knockdown of LPAR2 in the gastric cancer cell lines robustly reduced the LPA-induced β-catenin activity. An LPA exposure increased the ATP production by both oxidative phosphorylation and glycolysis, and this effect was abrogated with the addition of an LPAR2 antagonist and XAV393, which stabilizes the Axin and inhibits the β-catenin signaling pathway. Based on our findings, the possibility that LPA contributes to gastric cancer initiation and progression through the β-catenin signaling pathway as well as by the dysregulation of the energy metabolism via the LPAR2 receptor and Axin2, respectively, provides a novel insight into the mechanism of and possible therapeutic targets of gastric cancer.

A novel mechanism for the protection against acute lung injury by melatonin: mitochondrial quality control of lung epithelial cells is preserved through SIRT3-dependent deacetylation of SOD2

The mitochondrial quality control of lung epithelial cells is disturbed during sepsis, which contributes to abnormal mitochondrial function and acute lung injury. Melatonin is one of the primary hormones secreted by the pineal gland, displaying favorable antioxidative actions in sepsis and cardiopulmonary disease. However, the potential roles and molecular basis of melatonin in lipopolysaccharide (LPS)-treated lung epithelial cells have not been explored and reported. Herein, we investigated whether melatonin could protect against sepsis-induced acute lung injury (ALI) and LPS-treated lung epithelial cells through the mitochondrial quality control as well as its possible molecular targets. Wild type and Sirt3 knockout mice were intratracheally instilled with LPS for 12 h to construct an in vivo acute lung injury model. Both A549 lung epithelial cells and primary alveolar type II (AT-II) cells were used to explore the possible roles of melatonin in vitro by incubating with small interfering RNA against Sirt3. To determine the involvement of the melatonin receptor, cells and mice were treated with si Mtnr1b and luzindole. Melatonin pretreatment significantly inhibited pathological injury, inflammatory response, oxidative stress, and apoptosis in LPS-treated lung tissues and LPS-treated lung epithelial cells. Furthermore, melatonin also shifted the dynamic course of mitochondria from fission to fusion, inhibited mitophagy and fatty acid oxidation in LPS-treated lung epithelial cells in vitro and in vivo. However, SIRT3 inhibition abolished the protective roles of melatonin in acute lung injury. Mechanistically, we found that melatonin increased the activity and expression of SIRT3, which further promoted the deacetylation of SOD2 at K122 and K68. More importantly, melatonin exerted pulmonary protection by activating MTNR1B but not MTNR1A during ALI. Collectively, melatonin could preserve the mitochondrial quality control of lung epithelial cells through the deacetylation of SOD2 in a SIRT3-dependent manner, which eventually alleviated sepsis-induced injury, inflammation, oxidative stress, and apoptosis. Thus, melatonin may serve as a promising candidate against ALI in the future.

Electrophilic Aldehyde 4-Hydroxy-2-Nonenal Mediated Signaling and Mitochondrial Dysfunction

Reactive oxygen species (ROS), a by-product of aerobic life, are highly reactive molecules with unpaired electrons. The excess of ROS leads to oxidative stress, instigating the peroxidation of polyunsaturated fatty acids (PUFA) in the lipid membrane through a free radical chain reaction and the formation of the most bioactive aldehyde, known as 4-hydroxynonenal (4-HNE). 4-HNE functions as a signaling molecule and toxic product and acts mainly by forming covalent adducts with nucleophilic functional groups in proteins, nucleic acids, and lipids. The mitochondria have been implicated as a site for 4-HNE generation and adduction. Several studies clarified how 4-HNE affects the mitochondria's functions, including bioenergetics, calcium homeostasis, and mitochondrial dynamics. Our research group has shown that 4-HNE activates mitochondria apoptosis-inducing factor (AIFM2) translocation and facilitates apoptosis in mice and human heart tissue during anti-cancer treatment. Recently, we demonstrated that a deficiency of SOD2 in the conditional-specific cardiac knockout mouse increases ROS, and subsequent production of 4-HNE inside mitochondria leads to the adduction of several mitochondrial respiratory chain complex proteins. Moreover, we highlighted the physiological functions of HNE and discussed their relevance in human pathophysiology and current discoveries concerning 4-HNE effects on mitochondria.

The underlying pathological mechanism of ferroptosis in the development of cardiovascular disease

Cardiovascular diseases (CVDs) have been attracting the attention of academic society for decades. Numerous researchers contributed to figuring out the core mechanisms underlying CVDs. Among those, pathological decompensated cellular loss posed by cell death in different kinds, namely necrosis, apoptosis and necroptosis, was widely regarded to accelerate the pathological development of most heart diseases and deteriorate cardiac function. Recently, apart from programmed cell death revealed previously, ferroptosis, a brand-new cellular death identified by its ferrous-iron-dependent manner, has been demonstrated to govern the occurrence and development of different cardiovascular disorders in many types of research as well. Therefore, clarifying the regulatory function of ferroptosis is conducive to finding out strategies for cardio-protection in different conditions and improving the prognosis of CVDs. Here, molecular mechanisms concerned are summarized systematically and categorized to depict the regulatory network of ferroptosis and point out potential therapeutic targets for diverse cardiovascular disorders.

Mitochondrial PKM2 deacetylation by procyanidin B2-induced SIRT3 upregulation alleviates lung ischemia/reperfusion injury

Apoptosis is a critical event in the pathogenesis of lung ischemia/reperfusion (I/R) injury. Sirtuin 3 (SIRT3), an important deacetylase predominantly localized in mitochondria, regulates diverse physiological processes, including apoptosis. However, the detailed mechanisms by which SIRT3 regulates lung I/R injury remain unclear. Many polyphenols strongly regulate the sirtuin family. In this study, we found that a polyphenol compound, procyanidin B2 (PCB2), activated SIRT3 in mouse lungs. Due to this effect, PCB2 administration attenuated histological lesions, relieved pulmonary dysfunction, and improved the survival rate of the murine model of lung I/R injury. Additionally, this treatment inhibited hypoxia/reoxygenation (H/R)-induced A549 cell apoptosis and rescued Bcl-2 expression. Using Sirt3-knockout mice and specific SIRT3 knockdown in vitro, we further found that SIRT3 strongly protects against lung I/R injury. Sirt3 deficiency or enzymatic inactivation substantially aggravated lung I/R-induced pulmonary lesions, promoted apoptosis, and abolished PCB2-mediated protection. Mitochondrial pyruvate kinase M2 (PKM2) inhibits apoptosis by stabilizing Bcl-2. Here, we found that PKM2 accumulates and is hyperacetylated in mitochondria upon lung I/R injury. By screening the potential sites of PKM2 acetylation, we found that SIRT3 deacetylates the K433 residue of PKM2 in A549 cells. Transfection with a deacetylated mimic plasmid of PKM2 noticeably reduced apoptosis, while acetylated mimic transfection abolished the protective effect of PKM2. Furthermore, PKM2 knockdown or inhibition in vivo significantly abrogated the antiapoptotic effects of SIRT3 upregulation. Collectively, this study provides the first evidence that the SIRT3/PKM2 pathway is a protective target for the suppression of apoptosis in lung I/R injury. Moreover, this study identifies K433 deacetylation of PKM2 as a novel modification that regulates its anti-apoptotic activity. In addition, PCB2-mediated modulation of the SIRT3/PKM2 pathway may significantly protect against lung I/R injury, suggesting a novel prophylactic strategy for lung I/R injury.

Modulation of Reactive Oxygen Species Homeostasis as a Pleiotropic Effect of Commonly Used Drugs

Age-associated diseases represent a growing burden for global health systems in our aging society. Consequently, we urgently need innovative strategies to counteract these pathological disturbances. Overwhelming generation of reactive oxygen species (ROS) is associated with age-related damage, leading to cellular dysfunction and, ultimately, diseases. However, low-dose ROS act as crucial signaling molecules and inducers of a vaccination-like response to boost antioxidant defense mechanisms, known as mitohormesis. Consequently, modulation of ROS homeostasis by nutrition, exercise, or pharmacological interventions is critical in aging. Numerous nutrients and approved drugs exhibit pleiotropic effects on ROS homeostasis. In the current review, we provide an overview of drugs affecting ROS generation and ROS detoxification and evaluate the potential of these effects to counteract the development and progression of age-related diseases. In case of inflammation-related dysfunctions, cardiovascular- and neurodegenerative diseases, it might be essential to strengthen antioxidant defense mechanisms in advance by low ROS level rises to boost the individual ROS defense mechanisms. In contrast, induction of overwhelming ROS production might be helpful to fight pathogens and kill cancer cells. While we outline the potential of ROS manipulation to counteract age-related dysfunction and diseases, we also raise the question about the proper intervention time and dosage.

α-Lipoic acid ameliorates inflammation state and oxidative stress by reducing the content of bioactive lipid derivatives in the left ventricle of rats fed a high-fat diet

Lipid mediators derived from arachidonic acid (AA) are implicated with the occurrence of inflammation and oxidative stress. The current knowledge of AA metabolism focuses on searching for the therapeutic strategy to subvert affected AA metabolism. The aim of our study was to evaluate the potential protective effect of chronic α-lipoic acid (α-LA) supplementation on myocardial inflammation state and oxidative stress in obesity-related cardiovascular dysfunction. The experiment was carried out on male Wistar rats receiving a standard or a high-fat diets with intragastric α-LA administration for 8 weeks. Plasma and myocardial AA concentration was determined using gas-liquid chromatography (GLC). The Western blot technique was used to examine the expression of proteins from the inflammatory pathway. The content of selected cytokines, inflammatory mediators, and oxidative stress indicators was detected by ELISA, colorimetric, and multiplex assay kits. Our results revealed that α-LA caused a notable reduction in AA content, mainly in the phospholipid fraction with a simultaneous diminishment in the synthesis of pro-inflammatory mediators, i.e., prostaglandin E2, leukotrienes B4 and C4 by decreasing the expression of COX-2 and 5-LOX. α-LA also augmented the level of antioxidative SOD2 and GSH and decreased the level of lipid peroxidation products, which improved oxidative system impairment in the left ventricle tissue. The data clearly showed that α-lipoic acid has a significant role in inflammation and oxidative stress development ameliorating the risk of cardiac obesity induced by high-fat feeding.

Rotenone-Induced 4-HNE Aggresome Formation and Degradation in HL-1 Cardiomyocytes: Role of Autophagy Flux

Reactive oxygen species (ROS) cause oxidative stress by generating reactive aldehydes known as 4-hydroxynonenal (4-HNE). 4-HNE modifies protein via covalent adduction; however, little is known about the degradation mechanism of 4-HNE-adducted proteins. Autophagy is a dynamic process that maintains cellular homeostasis by removing damaged organelles and proteins. In this study, we determined the role of a superoxide dismutase (SOD) mimetic MnTnBuOE-2-PyP⁵⁺ (MnP, BMX-001) on rotenone-induced 4-HNE aggresome degradation in HL-1 cardiomyocytes. A rotenone treatment (500 nM) given for 24 h demonstrated both increased ROS and 4-HNE aggresome accumulation in HL-1 cardiomyocytes. In addition, cardiomyocytes treated with rotenone displayed an increase in the autophagy marker LC3-II, as shown by immunoblotting and immunofluorescence. A pre-treatment with MnP (20 µM) for 24 h attenuated rotenone-induced ROS formation. An MnP pre-treatment showed decreased 4-HNE aggresomes and LC3-II formation. A rotenone-induced increase in autophagosomes was attenuated by a pre-treatment with MnP, as shown by fluorescent-tagged LC3 (tfLC3). Rotenone increased tubulin hyperacetylation through the ROS-mediated pathway, which was attenuated by MnP. The disruption of autophagy caused HL-1 cell death because a 3-methyladenine inhibitor of autophagosomes caused reduced cell death. Yet, rapamycin, an inducer of autophagy, increased cell death. These results indicated that a pre-treatment with MnP decreased rotenone-induced 4-HNE aggresomes by enhancing the degradation process.

Mitochondrial Sirtuin-3 (SIRT3) Prevents Doxorubicin-Induced Dilated Cardiomyopathy by Modulating Protein Acetylation and Oxidative Stress

BACKGROUND

High doses of doxorubicin put cancer patients at risk for developing dilated cardiomyopathy. Previously, we showed that doxorubicin treatment decreases SIRT3 (sirtuin 3), the main mitochondrial deacetylase and increases protein acetylation in rat cardiomyocytes. Here, we hypothesize that SIRT3 expression can attenuate doxorubicin induced dilated cardiomyopathy in vivo by preventing the acetylation of mitochondrial proteins.

METHODS

Nontransgenic, M3-SIRT3 (truncated SIRT3; short isoform), and M1-SIRT3 (full-length SIRT3; mitochondrial localized) transgenic mice were treated with doxorubicin for 4 weeks (8 mg/kg body weight per week). Echocardiography was performed to assess cardiac structure and function and validated by immunohistochemistry and immunofluorescence (n=4-10). Mass spectrometry was performed on cardiac mitochondrial peptides in saline (n=6) and doxorubicin (n=5) treated hearts. Validation was performed in doxorubicin treated primary rat and human induced stem cell derived cardiomyocytes transduced with adenoviruses for M3-SIRT3 and M1-SIRT3 and deacetylase deficient mutants (n=4-10).

RESULTS

Echocardiography revealed that M3-SIRT3 transgenic mice were partially resistant to doxorubicin induced changes to cardiac structure and function whereas M1-SIRT3 expression prevented cardiac remodeling and dysfunction. In doxorubicin hearts, 37 unique acetylation sites on mitochondrial proteins were altered. Pathway analysis revealed these proteins are involved in energy production, fatty acid metabolism, and oxidative stress resistance. Increased M1-SIRT3 expression in primary rat and human cardiomyocytes attenuated doxorubicin-induced superoxide formation, whereas deacetylase deficient mutants were unable to prevent oxidative stress.

CONCLUSIONS

Doxorubicin reduced SIRT3 expression and markedly affected the cardiac mitochondrial acetylome. Increased M1-SIRT3 expression in vivo prevented doxorubicin-induced cardiac dysfunction, suggesting that SIRT3 could be a potential therapeutic target for mitigating doxorubicin-induced dilated cardiomyopathy.

Mitochondrial-Targeted Therapies Require Mitophagy to Prevent Oxidative Stress Induced by SOD2 Inactivation in Hypertrophied Cardiomyocytes

Heart failure, mostly associated with cardiac hypertrophy, is a major cause of illness and death. Oxidative stress causes accumulation of reactive oxygen species (ROS), leading to mitochondrial dysfunction, suggesting that mitochondria-targeted therapies could be effective in this context. The purpose of this work was to determine whether mitochondria-targeted therapies could improve cardiac hypertrophy induced by mitochondrial ROS. We used neonatal (NCMs) and adult (ACMs) rat cardiomyocytes hypertrophied by isoproterenol (Iso) to induce mitochondrial ROS. A decreased interaction between sirtuin 3 and superoxide dismutase 2 (SOD2) induced SOD2 acetylation on lysine 68 and inactivation, leading to mitochondrial oxidative stress and dysfunction and hypertrophy after 24 h of Iso treatment. To counteract these mechanisms, we evaluated the impact of the mitochondria-targeted antioxidant mitoquinone (MitoQ). MitoQ decreased mitochondrial ROS and hypertrophy in Iso-treated NCMs and ACMs but altered mitochondrial structure and function by decreasing mitochondrial respiration and mitophagy. The same decrease in mitophagy was found in human cardiomyocytes but not in fibroblasts, suggesting a cardiomyocyte-specific deleterious effect of MitoQ. Our data showed the importance of mitochondrial oxidative stress in the development of cardiomyocyte hypertrophy. We observed that targeting mitochondria by MitoQ in cardiomyocytes impaired the metabolism through defective mitophagy, leading to accumulation of deficient mitochondria.

FGF6 promotes cardiac repair after myocardial infarction by inhibiting the Hippo pathway

OBJECTIVES

Myocardial infarction (MI) commonly occurs in patients with coronary artery disease and have high mortality. Current clinical strategies for MI still limited to reducing the death of myocardial cells but failed to replace these cells. This study aimed to investigate the role of fibroblast growth factor 6 (FGF6) in enhancing the proliferative potential of cardiomyocytes (CMs) after ischemic injury via the Hippo pathway.

MATERIALS AND METHODS

Expression of FGF6 protein was analysed in mice with MI induced by ligation of the left anterior descending coronary artery. Activation of the Hippo pathway and the proliferation potential were examined in ischemic CMs, treated with FGF6 protein or transfected with an adeno-virus carrying FGF6 sh-RNA. Immunofluorescence staining and western blotting were performed to assess the relationship between FGF6 and the Hippo pathway.

RESULTS

We found that FGF6 expression was significantly increased in the MI mouse model. Knockdown of FGF6 synthesis resulted in poorer heart function after MI. By contrast, treatment with recombinant human FGF6 protein improved heart function, reduced infarct size, and promoted cardiac repair. Additionally, FGF6 restrains the activation of the Hippo pathway and subsequently promotes nuclear accumulation of YAP. This was largely counteracted by treatment with extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor U0126.

CONCLUSION

FGF6 inhibits the Hippo pathway via ERK1/2, and facilitates nuclear translocation of YAP, and thereby promotes cardiac repair after MI.

Superoxide Radicals in the Execution of Cell Death

Superoxide is a primary oxygen radical that is produced when an oxygen molecule receives one electron. Superoxide dismutase (SOD) plays a primary role in the cellular defense against an oxidative insult by ROS. However, the resulting hydrogen peroxide is still reactive and, in the presence of free ferrous iron, may produce hydroxyl radicals and exacerbate diseases. Polyunsaturated fatty acids are the preferred target of hydroxyl radicals. Ferroptosis, a type of necrotic cell death induced by lipid peroxides in the presence of free iron, has attracted considerable interest because of its role in the pathogenesis of many diseases. Radical electrons, namely those released from mitochondrial electron transfer complexes, and those produced by enzymatic reactions, such as lipoxygenases, appear to cause lipid peroxidation. While GPX4 is the most potent anti-ferroptotic enzyme that is known to reduce lipid peroxides to alcohols, other antioxidative enzymes are also indirectly involved in protection against ferroptosis. Moreover, several low molecular weight compounds that include α-tocopherol, ascorbate, and nitric oxide also efficiently neutralize radical electrons, thereby suppressing ferroptosis. The removal of radical electrons in the early stages is of primary importance in protecting against ferroptosis and other diseases that are related to oxidative stress.

Identification of Resolvin D1 and Protectin D1 as Potential Therapeutic Agents for Treating Kidney Stones

Intrarenal calcium oxalate (CaOx) crystals induce renal tubular epithelial cell (TEC) inflammatory and oxidative injury. This study is aimed at exploring potential therapeutic lipid components in kidney stones because lipids are involved in the development of several diseases and indicate the risk of kidney stones. Serum specimens were collected from 35 kidney stone patients and 35 normal controls. The lipid components in serum were measured, and differences were analyzed. The documented biological importance was comprehensively reviewed to identify lipids that differed significantly between the two groups to find potential agents associated with kidney stones. CaOx nephrocalcinosis mouse model was established to examine the therapeutic effects of specific lipids on CaOx deposition and CaOx-induced oxidative renal injury. Several lipids with significantly different levels were present in the serum of patients with stones and normal controls. Resolvin D1 (RvD1) (4.93-fold change, P < 0.001) and protectin D1 (PD1) (5.06-fold change, P < 0.001) were significantly decreased in the serum of patients with kidney stones, and an integrative review suggested that these factors might be associated with inflammatory responses, which is a crucial mechanism associated with stone damage. The administration of RvD1 and PD1 significantly inhibited kidney CaOx deposition and suppressed CaOx-induced renal tubular cell inflammatory injury and necrosis in a CaOx nephrocalcinosis mouse model. Furthermore, RvD1 and PD1 facilitated the expression of the oxidative indicator superoxide dismutase 2 (SOD2), inhibited NADPH oxidase 2 (NOX2) expression, and diminished intracellular reactive oxygen species (ROS) levels. This study preliminarily elucidated the role of lipids in kidney stones. The inhibitory effects of RvD1 and PD1 on oxidative damage induced by CaOx deposition provide a promising perspective for kidney stone treatment strategies.

Endothelial superoxide dismutase 2 is decreased in sickle cell disease and regulates fibronectin processing

Sickle cell disease (SCD) is a genetic red blood cell disorder characterized by increased reactive oxygen species (ROS) and a concordant reduction in antioxidant capacity in the endothelium. Superoxide dismutase 2 (SOD2) is a mitochondrial-localized enzyme that catalyzes the dismutation of superoxide to hydrogen peroxide. Decreased peripheral blood expression of SOD2 is correlated with increased hemolysis and cardiomyopathy in SCD. Here, we report for the first time that endothelial cells exhibit reduced SOD2 protein expression in the pulmonary endothelium of SCD patients. To investigate the impact of decreased SOD2 expression in the endothelium, SOD2 was knocked down in human pulmonary microvascular endothelial cells (hPMVECs). We found that SOD2 deficiency in hPMVECs results in endothelial cell dysfunction, including reduced cellular adhesion, diminished migration, integrin protein dysregulation, and disruption of permeability. Furthermore, we uncover that SOD2 mediates changes in endothelial cell function via processing of fibronectin through its inability to facilitate dimerization. These results demonstrate that endothelial cells are deficient in SOD2 expression in SCD patients and suggest a novel pathway for SOD2 in regulating fibronectin processing.

The Interplay of Hypoxia Signaling on Mitochondrial Dysfunction and Inflammation in Cardiovascular Diseases and Cancer: From Molecular Mechanisms to Therapeutic Approaches

Simple Summary

The regulation of hypoxia has recently emerged as having a central impact in mitochondrial function and dysfunction in various diseases, including the major disorders threatening worldwide: cardiovascular diseases and cancer. Despite the studies in this matter, its effective role in protection and disease progression even though its direct molecular mechanism in both disorders is still to be elucidated. This review aims to cover the current knowledge about the effect of hypoxia on mitochondrial function and dysfunction, and inflammation, in cardiovascular diseases and cancer, and reports further therapeutic strategies based on the modulation of hypoxic pathways.

Abstract

Cardiovascular diseases (CVDs) and cancer continue to be the primary cause of mortality worldwide and their pathomechanisms are a complex and multifactorial process. Insufficient oxygen availability (hypoxia) plays critical roles in the pathogenesis of both CVDs and cancer diseases, and hypoxia-inducible factor 1 (HIF-1), the main sensor of hypoxia, acts as a central regulator of multiple target genes in the human body. Accumulating evidence demonstrates that mitochondria are the major target of hypoxic injury, the most common source of reactive oxygen species during hypoxia and key elements for inflammation regulation during the development of both CVDs and cancer. Taken together, observations propose that hypoxia, mitochondrial abnormality, oxidative stress, inflammation in CVDs, and cancer are closely linked. Based upon these facts, this review aims to deeply discuss these intimate relationships and to summarize current significant findings corroborating the molecular mechanisms and potential therapies involved in hypoxia and mitochondrial dysfunction in CVDs and cancer.

Extracellular Superoxide Dismutase (EC-SOD) Regulates Gene Methylation and Cardiac Fibrosis During Chronic Hypoxic Stress

Chronic hypoxic stress induces epigenetic modifications mainly DNA methylation in cardiac fibroblasts, inactivating tumor suppressor genes (RASSF1A) and activating kinases (ERK1/2) leading to fibroblast proliferation and cardiac fibrosis. The Ras/ERK signaling pathway is an intracellular signal transduction critically involved in fibroblast proliferation. RASSF1A functions through its effect on downstream ERK1/2. The antioxidant enzyme, extracellular superoxide dismutase (EC-SOD), decreases oxidative stress from chronic hypoxia, but its effects on these epigenetic changes have not been fully explored. To test our hypothesis, we used an in-vitro model: wild-type C57B6 male mice (WT) and transgenic males with an extra copy of human hEC-SOD (TG). The studied animals were housed in hypoxia (10% O₂) for 21 days. The right ventricular tissue was studied for cardiac fibrosis markers using RT-PCR and Western blot analyses. Primary C57BL6 mouse cardiac fibroblast tissue culture was used to study the in-vitro model, the downstream effects of RASSF-1 expression and methylation, and its relation to ERK1/2. Our findings showed a significant increase in cardiac fibrosis markers: Collagen 1, alpha smooth muscle actin (ASMA), and SNAIL, in the WT hypoxic animals as compared to the TG hypoxic group (p < 0.05). The expression of DNA methylation enzymes (DNMT 1&3b) was significantly increased in the WT hypoxic mice as compared to the hypoxic TG mice (p < 0.001). RASSF1A expression was significantly lower and ERK1/2 was significantly higher in hypoxia WT compared to the hypoxic TG group (p < 0.05). Use of SiRNA to block RASSF1A gene expression in murine cardiac fibroblast tissue culture led to increased fibroblast proliferation (p < 0.05). Methylation of the RASSF1A promoter region was significantly reduced in the TG hypoxic group compared to the WT hypoxic group (0.59 vs. 0.75, respectively). Based on our findings, we can speculate that EC-SOD significantly attenuates RASSF1A gene methylation and can alleviate cardiac fibrosis induced by hypoxia.

Exploration the Mechanism of Doxorubicin-Induced Heart Failure in Rats by Integration of Proteomics and Metabolomics Data

Heart failure is a common systemic disease with high morbidity and mortality worldwide. Doxorubicin (DOX) is a commonly used anthracycline broad-spectrum antitumor antibiotic with strong antitumor effect and definite curative effect. However, cardiotoxicity is the adverse reaction of drug dose cumulative toxicity, but the mechanism is still unclear. In this study, proteomics and metabonomics techniques were used to analyze the tissue and plasma of DOX-induced heart failure (HF) in rats and to clarify the molecular mechanism of the harmful effects of DOX on cardiac metabolism and function in rats from a new point of view. The results showed that a total of 278 proteins with significant changes were identified by quantitative proteomic analysis, of which 118 proteins were significantly upregulated and 160 proteins were significantly downregulated in myocardial tissue. In the metabonomic analysis, 21 biomarkers such as L-octanoylcarnitine, alpha-ketoglutarate, glutamine, creatine, and sphingosine were detected. Correlation analysis showed that DOX-induced HF mainly affected phenylalanine, tyrosine, and tryptophan biosynthesis, D-glutamine and D-glutamate metabolism, phenylalanine metabolism, biosynthesis of unsaturated fatty acids, and other metabolic pathways, suggesting abnormal amino acid metabolism, fatty acid metabolism, and glycerol phospholipid metabolism. It is worth noting that we have found the key upstream target of DOX-induced HF, PTP1B, which inhibits the expression of HIF-1α by inhibiting the phosphorylation of IRS, leading to disorders of fatty acid metabolism and glycolysis, which together with the decrease of Nrf2, SOD, Cytc, and AK4 proteins lead to oxidative stress. Therefore, we think that PTP1B may play an important role in the development of heart failure induced by doxorubicin and can be used as a potential target for the treatment of heart failure.