Mitochondrial Production Research Articles

Development of novel cytoprotective small compounds inhibiting mitochondria-dependent cell death

We identified cytoprotective small molecules (CSMs) by a cell-based high-throughput screening of Bax inhibitors. Through a medicinal chemistry program, M109S was developed, which is orally bioactive and penetrates the blood-brain/retina barriers. M109S protected retinal cells in ocular disease mouse models. M109S directly interacted with Bax and inhibited the conformational change and mitochondrial translocation of Bax. M109S inhibited ABT-737-induced apoptosis both in Bax-only and Bak-only mouse embryonic fibroblasts. M109S also inhibited apoptosis induced by staurosporine, etoposide, and obatoclax. M109S decreased maximal mitochondrial oxygen consumption rate and reactive oxygen species production, whereas it increased glycolysis. These effects on cellular metabolism may contribute to the cytoprotective activity of M109S. M109S is a novel small molecule protecting cells from mitochondria-dependent apoptosis both invitro and invivo. M109S has the potential to become a research tool for studying cell death mechanisms and to develop therapeutics targeting mitochondria-dependent cell death pathway.

Isolation of Latilactobacillus curvatus with Enhanced Nitric Oxide Synthesis from Korean Traditional Fermented Food and Investigation of Its Probiotic Properties.

Nitric oxide (NO) is a free radical associated with physiological functions such as blood pressure regulation, cardiovascular health, mitochondrial production, calcium transport, oxidative stress, and skeletal muscle repair. This study aimed to isolate Latilactobacillus curvatus strains with enhanced NO production from the traditional Korean fermented food, jangajji, and evaluate their probiotic properties for industrial purposes. When cells were co-cultured with various bacterial stimulants, NO production generally increased, and NO synthesis was observed in the range of 20-40 mg/mL. The selected strains of Lat. curvatus were resistant to acid and bile conditions and with variable effectiveness (1-14%) in adhering to Caco-2 cells. Most bacterial strains can inhibit the growth of various pathogens. In addition, they are capable of reducing cholesterol levels via assimilation of cholesterol at 10-50%. Among the selected NO synthases from Lat. curvatus strains, the strain JBCC38 showed the highest capacity to scavenge ABTS (30.1%) and DPPH radicals (39.4%). Moreover, these strains exhibited immunomodulatory properties. The production of TNF-α and IL-6 in the macrophages treated with various bacterial stimulants was induced in all the selected strains.

Partial skeletal muscle-specific Drp1 knockout enhances insulin sensitivity in diet-induced obese mice, but not in lean mice

ObjectiveDynamin-related protein 1 (Drp1) is the key regulator of mitochondrial fission. We and others have reported a strong correlation between enhanced Drp1 activity and impaired skeletal muscle insulin sensitivity. This study aimed to determine whether Drp1 directly regulates skeletal muscle insulin sensitivity and whole-body glucose homeostasis. MethodsWe employed tamoxifen-inducible skeletal muscle-specific heterozygous Drp1 knockout mice (mDrp1+/−). Male mDrp1+/− and wildtype (WT) mice were fed with either a high-fat diet (HFD) or low-fat diet (LFD) for four weeks, followed by tamoxifen injections for five consecutive days, and remained on their respective diet for another four weeks. In addition, we used primary human skeletal muscle cells (HSkMC) from lean, insulin-sensitive, and severely obese, insulin-resistant humans and transfected the cells with either a Drp1 shRNA (shDrp1) or scramble shRNA construct. Skeletal muscle and whole-body insulin sensitivity, skeletal muscle insulin signaling, mitochondrial network morphology, respiration, and H2O2 production were measured. ResultsPartial deletion of the Drp1 gene in skeletal muscle led to improved whole-body glucose tolerance and insulin sensitivity (P < 0.05) in diet-induced obese, insulin-resistant mice but not in lean mice. Analyses of mitochondrial structure and function revealed that the partial deletion of the Drp1 gene restored mitochondrial dynamics, improved mitochondrial morphology, and reduced mitochondrial Complex I- and II-derived H2O2 (P < 0.05) under the condition of diet-induced obesity. In addition, partial deletion of Drp1 in skeletal muscle resulted in elevated circulating FGF21 (P < 0.05) and in a trend towards increase of FGF21 expression in skeletal muscle tissue (P = 0.095). In primary myotubes derived from severely obese, insulin-resistant humans, ShRNA-induced-knockdown of Drp1 resulted in enhanced insulin signaling, insulin-stimulated glucose uptake and reduced cellular reactive oxygen species (ROS) content compared to the shScramble-treated myotubes from the same donors (P < 0.05). ConclusionThese data demonstrate that partial loss of skeletal muscle-specific Drp1 expression is sufficient to improve whole-body glucose homeostasis and insulin sensitivity under obese, insulin-resistant conditions, which may be, at least in part, due to reduced mitochondrial H2O2 production. In addition, our findings revealed divergent effects of Drp1 on whole-body metabolism under lean healthy or obese insulin-resistant conditions in mice.

Redox Profile of Skeletal Muscles: Implications for Research Design and Interpretation.

Mammalian skeletal muscles contain varying proportions of Type I and II fibers, which feature different structural, metabolic and functional properties. According to these properties, skeletal muscles are labeled as 'red' or 'white', 'oxidative' or 'glycolytic', 'slow-twitch' or 'fast-twitch', respectively. Redox processes (i.e., redox signaling and oxidative stress) are increasingly recognized as a fundamental part of skeletal muscle metabolism at rest, during and after exercise. The aim of the present review was to investigate the potential redox differences between slow- (composed mainly of Type I fibers) and fast-twitch (composed mainly of Type IIa and IIb fibers) muscles at rest and after a training protocol. Slow-twitch muscles were almost exclusively represented in the literature by the soleus muscle, whereas a wide variety of fast-twitch muscles were used. Based on our analysis, we argue that slow-twitch muscles exhibit higher antioxidant enzyme activity compared to fast-twitch muscles in both pre- and post-exercise training. This is also the case between heads or regions of fast-twitch muscles that belong to different subcategories, namely Type IIa (oxidative) versus Type IIb (glycolytic), in favor of the former. No safe conclusion could be drawn regarding the mRNA levels of antioxidant enzymes either pre- or post-training. Moreover, slow-twitch skeletal muscles presented higher glutathione and thiol content as well as higher lipid peroxidation levels compared to fast-twitch. Finally, mitochondrial hydrogen peroxide production was higher in fast-twitch muscles compared to slow-twitch muscles at rest. This redox heterogeneity between different muscle types may have ramifications in the analysis of muscle function and health and should be taken into account when designing exercise studies using specific muscle groups (e.g., on an isokinetic dynamometer) or isolated muscle fibers (e.g., electrical stimulation) and may deliver a plausible explanation for the conflicting results about the ergogenic potential of antioxidant supplements.

Saikosaponin A alleviates Staphylococcus aureus-induced mastitis in mice by inhibiting ferroptosis via SIRT1/Nrf2 pathway.

Mastitis is a common and serious bacterial infection of the mammary gland. Saikosaponin A (SSA) is a triterpenoid saponin isolated from Bupleurum falcatum that has the ability to treat various diseases. However, little is known about the role of SSA in achieving mastitis remission. Here, we found that SSA alleviated Staphylococcus aureus (S. aureus)-induced mastitis by attenuating inflammation and maintaining blood-milk barrier integrity. Furthermore, S. aureus activated nuclear factor kappa B (NF-κB) pathway by upregulated p-p65 and p-IκB. S. aureus also induced ferroptosis in mammary gland in mice, mainly characterized by excessive iron accumulation, mitochondrial morphological changes and impaired antioxidant production. However, S. aureus-induced NF-κB activation and ferroptosis were prevented by SSA. Moreover, SAA could upregulate the expression of SIRT1, Nrf2, HO-1 and GPX4. And the inhibitory effects of SAA on inflammation and ferroptosis were reversed by SIRT1 inhibitor EX-527. In conclusion, SAA protected S. aureus-induced mastitis through suppressing inflammation and ferroptosis by activating SIRT1/Nrf2 pathway.

THIAMINE AND HIGH DOSE INSULIN TREATMENT FOR SEPSIS

Sepsis is a major health problem and accounts for 20% of deaths worldwide. It is the most expensive condition treated in United States hospitals at $62 billion per year or about $46,000 per patient. Treatment consisting largely of fluid resuscitation and antibiotics has only a marginal impact. Mortality is about 27% for hospitalised patients and about 42% for patients in intensive care. There are two phases of sepsis – a hyperinflammatory phase and a subsequent hypoinflammatory phase. During the hyperinflammatory phase, the metabolic rate increases, and this is associated with an increase in body temperature and a rapid escalation of immune system functioning including increased numbers of leucocytes and their migration to infected and damaged tissues and increased supply and consumption of glucose to fuel this immune system. During the subsequent hypoinflammatory phase, the metabolic rate decreases, and this is associated with a decrease in body temperature and a generalised decrease in the physiological activity of many organs including the immune system akin to hibernation. The activated immune system has priority for the available glucose over most other organs and physiological functions during such potentially life-threatening circumstances. Thus, adenosine triphosphate (ATP) production by mitochondria (the source of energy at the cellular level for the organism as a whole) also has a lower priority for the available glucose relative to the activated immune system. If glucose availability is threatened, then the mitochondrial production of ATP is partially or substantially suppressed in favour of glycolysis because glycolysis can rapidly produce large quantities of ATP that are necessary for immune cell function in infected, anaerobic, ischaemic, or damaged tissues. However, glycolysis is only a temporary fix as it cannot produce the quantities of ATP necessary on an ongoing basis for the normal functioning of the healthy animal. Mitochondrial production of ATP must be recommenced for full recovery. It appears that the partial or substantial suppression of mitochondrial production of ATP by activation of the immune response becomes relatively fixated in some patients, leading to a substantial ATP deficit. This is the fundamental issue of sepsis. This paper reviews the metabolism of glucose and insulin during sepsis and concludes that high dose insulin with mild hyperglycaemia in conjunction with the intravenous administration of thiamine, an inhibitor of the pyruvate dehydrogenase kinase enzymes, to re-establish physiological ATP production by mitochondria, administered early in the hypometabolic (hypoinflammatory) phase of sepsis, may enhance survival relative to thiamine alone.

Mitochondrial morphology governs ATP production rate.

Life is based on energy conversion. In particular, in the nervous system, significant amounts of energy are needed to maintain synaptic transmission and homeostasis. To a large extent, neurons depend on oxidative phosphorylation in mitochondria to meet their high energy demand. For a comprehensive understanding of the metabolic demands in neuronal signaling, accurate models of ATP production in mitochondria are required. Here, we present a thermodynamically consistent model of ATP production in mitochondria based on previous work. The significant improvement of the model is that the reaction rate constants are set such that detailed balance is satisfied. Moreover, using thermodynamic considerations, the dependence of the reaction rate constants on membrane potential, pH, and substrate concentrations are explicitly provided. These constraints assure that the model is physically plausible. Furthermore, we explore different parameter regimes to understand in which conditions ATP production or its export are the limiting steps in making ATP available in the cytosol. The outcomes reveal that, under the conditions used in our simulations, ATP production is the limiting step and not its export. Finally, we performed spatial simulations with nine 3-D realistic mitochondrial reconstructions and linked the ATP production rate in the cytosol with morphological features of the organelles.

Irreversible HER2 inhibitors overcome resistance to the RSL3 ferroptosis inducer in non-HER2 amplified luminal breast cancer.

Ferroptosis, a form of programed cell death, can be promoted by inhibitors of the xCT transporter (erastin) or GPX4 (RSL3). We found that GPX4, but not the xCT transporter, is selectively elevated in luminal breast cancer. Consistent with this observation, the majority of luminal breast cancer cell lines are exquisitely sensitive to RSL3 with limited sensitivity to erastin. In RSL3-resistant, but not sensitive, luminal breast cancer cell lines, RSL3 induces HER2 pathway activation. Irreversible HER2 inhibitors including neratinib reversed RSL3 resistance in constitutively RSL3-resistant cell lines. Combination treatment with RSL3 and neratinib increases ferroptosis through mitochondrial iron-dependent reactive oxygen species production and lipid peroxidation. RSL3 also activated replication stress and concomitant S phase and G2/M blockade leading to sensitivity to targeting the DNA damage checkpoint. Together, our data support the exploration of RSL3 combined with irreversible HER2 inhibitors in clinical trials.

Isomaculosidine facilitates NLRP3 inflammasome activation by promoting mitochondrial reactive oxygen species production and causes idiosyncratic liver injury

Ethnopharmacological relevanceDictamnus dasycarpus Turcz. (Dictamni Cortex, DC), a Chinese herbal medicine, is commonly used for treating chronic dermatosis and rheumatism, but can also cause herb-induced liver injury (HILI). Our study has demonstrated that DC can induce idiosyncratic HILI, but the mechanism remains unknown. The NLRP3 inflammasome has become a major target for addressing many diseases. The activation of NLRP3 inflammasome is responsible for many liver-related inflammatory diseases, including idiosyncratic HILI. Aim of the studyThe objective of our study was to demonstrate the mechanism underlying the idiosyncratic HILI induced by DC and clarify the susceptible component in DC. Materials and methodsBone marrow-derived macrophages (BMDMs) and THP1 cells were selected to assess the effect of isomaculosidine (IMD) on NLRP3 inflammasome activation in vitro. Western blot, ELISA and Caspase-Glo® 1 Inflammasome Assay, flow cytometry and Immunofluorescence were employed to detect the mechanism of IMD on NLRP3 inflammasome activation. To assess the efficacy of IMD in vivo, mice were intravenously administrated with LPS and then IMD were injected intraperitoneally for 6 h. ResultsThe results of our in vitro studies demonstrate that IMD, the major constituent of DC, specifically promoted ATP- and nigericin-induced activation of NLRP3 inflammasome, but not NLRC4 and AIM2 inflammasomes. Additionally, IMD promoted nigericin-induced ASC oligomerization. Notably, synergistic induction of mtROS played a key role on the activation of NLRP3 inflammasome. IMD increased the mtROS production in the activation of NLRP3 inflammasome induced by nigericin. In addition, the results of our in vivo study showed that the combination of nonhepatotoxic doses of LPS and IMD can increase the levels of ALT, AST, and DBIL, leading to liver injury. ConclusionsIMD specifically facilitated the activation of NLRP3 inflammasome induced by nigericin and ATP, which is responsible for DC-induced idiosyncratic HILI.

The Developmental Implications of Muscle-Targeted Magnetic Mitohormesis: A Human Health and Longevity Perspective.

Muscle function reflects muscular mitochondrial status, which, in turn, is an adaptive response to physical activity, representing improvements in energy production for de novo biosynthesis or metabolic efficiency. Differences in muscle performance are manifestations of the expression of distinct contractile-protein isoforms and of mitochondrial-energy substrate utilization. Powerful contractures require immediate energy production from carbohydrates outside the mitochondria that exhaust rapidly. Sustained muscle contractions require aerobic energy production from fatty acids by the mitochondria that is slower and produces less force. These two patterns of muscle force generation are broadly classified as glycolytic or oxidative, respectively, and require disparate levels of increased contractile or mitochondrial protein production, respectively, to be effectively executed. Glycolytic muscle, hence, tends towards fibre hypertrophy, whereas oxidative fibres are more disposed towards increased mitochondrial content and efficiency, rather than hypertrophy. Although developmentally predetermined muscle classes exist, a degree of functional plasticity persists across all muscles post-birth that can be modulated by exercise and generally results in an increase in the oxidative character of muscle. Oxidative muscle is most strongly correlated with organismal metabolic balance and longevity because of the propensity of oxidative muscle for fatty-acid oxidation and associated anti-inflammatory ramifications which occur at the expense of glycolytic-muscle development and hypertrophy. This muscle-class size disparity is often at odds with common expectations that muscle mass should scale positively with improved health and longevity. Brief magnetic-field activation of the muscle mitochondrial pool has been shown to recapitulate key aspects of the oxidative-muscle phenotype with similar metabolic hallmarks. This review discusses the common genetic cascades invoked by endurance exercise and magnetic-field therapy and the potential physiological differences with regards to human health and longevity. Future human studies examining the physiological consequences of magnetic-field therapy are warranted.

Mitochondrial pannexin1 controls cardiac sensitivity to ischaemia/reperfusion injury.

No effective therapy is available in clinics to protect the heart from ischaemia/reperfusion (I/R) injury. Endothelial cells are activated after I/R, which may drive the inflammatory response by releasing ATP through pannexin1 (Panx1) channels. Here, we investigated the role of Panx1 in cardiac I/R. Panx1 was found in cardiac endothelial cells, neutrophils, and cardiomyocytes. After in vivo I/R, serum Troponin-I, and infarct size were less pronounced in Panx1-/- mice, but leukocyte infiltration in the infarct area was similar between Panx1-/- and wild-type mice. Serum Troponin-I and infarct size were not different between mice with neutrophil-specific deletion of Panx1 and Panx1fl/fl mice, suggesting that cardioprotection by Panx1 deletion rather involved cardiomyocytes than the inflammatory response. Physiological cardiac function in wild-type and Panx1-/- hearts was similar. The time to onset of contracture and time to maximal contracture were delayed in Panx1-/- hearts, suggesting reduced sensitivity of these hearts to ischaemic injury. Moreover, Panx1-/- hearts showed better recovery of left ventricle developed pressure, cardiac contractility, and relaxation after I/R. Ischaemic preconditioning failed to confer further protection in Panx1-/- hearts. Panx1 was found in subsarcolemmal mitochondria (SSM). SSM in WT or Panx1-/- hearts showed no differences in morphology. The function of the mitochondrial permeability transition pore and production of reactive oxygen species in SSM was not affected, but mitochondrial respiration was reduced in Panx1-/- SSM. Finally, Panx1-/- cardiomyocytes had a decreased mitochondrial membrane potential and an increased mitochondrial ATP content. Panx1-/- mice display decreased sensitivity to cardiac I/R injury, resulting in smaller infarcts and improved recovery of left ventricular function. This cardioprotective effect of Panx1 deletion seems to involve cardiac mitochondria rather than a reduced inflammatory response. Thus, Panx1 may represent a new target for controlling cardiac reperfusion damage.

Six Functions of Respiration: Isn't It Time to Take Control over ROS Production in Mitochondria, and Aging Along with It?

Cellular respiration is associated with at least six distinct but intertwined biological functions. (1) biosynthesis of ATP from ADP and inorganic phosphate, (2) consumption of respiratory substrates, (3) support of membrane transport, (4) conversion of respiratory energy to heat, (5) removal of oxygen to prevent oxidative damage, and (6) generation of reactive oxygen species (ROS) as signaling molecules. Here we focus on function #6, which helps the organism control its mitochondria. The ROS bursts typically occur when the mitochondrial membrane potential (MMP) becomes too high, e.g., due to mitochondrial malfunction, leading to cardiolipin (CL) oxidation. Depending on the intensity of CL damage, specific programs for the elimination of damaged mitochondria (mitophagy), whole cells (apoptosis), or organisms (phenoptosis) can be activated. In particular, we consider those mechanisms that suppress ROS generation by enabling ATP synthesis at low MMP levels. We discuss evidence that the mild depolarization mechanism of direct ATP/ADP exchange across mammalian inner and outer mitochondrial membranes weakens with age. We review recent data showing that by protecting CL from oxidation, mitochondria-targeted antioxidants decrease lethality in response to many potentially deadly shock insults. Thus, targeting ROS- and CL-dependent pathways may prevent acute mortality and, hopefully, slow aging.

Endocrine disruptors and arterial hypertension: A developing story

Endocrine disrupting Chemicals (EDCs) are substances that interfere with hormones by several mechanisms including receptor activation or antagonism, changes in gene and protein expression, modification of signal transduction, and/or epigenetic modifications in hormone-producing cells. A survey conducted by the European Union in a Northern Italian region led to the discovery of a large environmental contamination of drinking water by perfluoroalkyl substances (PFAS). As the exposed population showed a high prevalence of arterial hypertension and cardiovascular disease, we decided to investigate if PFAS could enhance the biosynthesis of aldosterone. To this aim, we exposed human adrenocortical carcinoma HAC15 cells to PFAS and found that PFAS markedly increased aldosterone synthase (CYP11B2) gene expression and aldosterone secretion. Moreover, we found that they promoted reactive oxygen species (ROS) production in mitochondria, the organelles where aldosterone biosynthesis takes place. PFAS also enhanced the effects of the aldosterone secretagogue angiotensin II (Ang II) on CYP11B2 gene expression and aldosterone secretion. We also found that not only PFAS but also polychlorinated biphenyl 126 (PCB126), a chemical compound belonging to a different category of EDCs, can increase CYP11B2 gene expression and aldosterone secretion in adrenocortical cells. This novel information needs to be considered in the context of a widespread exposure to the most common EDC, that is excess Na+ intake, whose detrimental effects on human health occur in the setting of aldosterone production exceeding the physiological needs and lead to high blood pressure, congestion, and cardiovascular and renal damage.

Microbial energy metabolism fuels an intestinal macrophage niche in solitary isolated lymphoid tissues through purinergic signaling.

Maintaining macrophage (MΦ) heterogeneity is critical to ensure intestinal tissue homeostasis and host defense. The gut microbiota and host factors are thought to synergistically guide intestinal MΦ development, although the exact nature, regulation, and location of such collaboration remain unclear. Here, we report that microbial biochemical energy metabolism promotes colony-stimulating factor 2 (CSF2) production by group 3 innate lymphoid cells (ILC3s) within solitary isolated lymphoid tissues (SILTs) in a cell-extrinsic, NLRP3/P2X7R-dependent fashion in the steady state. Tissue-infiltrating monocytes accumulating around SILTs followed a spatially constrained, distinct developmental trajectory into SILT-associated MΦs (SAMs). CSF2 regulated the mitochondrial membrane potential and reactive oxygen species production of SAMs and contributed to the antimicrobial defense against enteric bacterial infections. Collectively, these findings identify SILTs and CSF2-producing ILC3s as a microanatomic niche for intestinal MΦ development and functional programming fueled by the integration of commensal microbial energy metabolism.

Abstract GS.101: Cardiomyocyte DCHS2 Inhibition Protects Against Heart Failure

Loss of cardiomyocytes (CMs) and impaired mitochondrial function are major causes of heart failure (HF). We recently found that cardiac Dachsous Cadherin-Related 2 (DCHS2) is induced in pathological hypertrophy and HF but inhibited by exercise. CM DCHS2 expression in vivo causes pathological hypertrophy while its deletion induces physiological hypertrophy and increases markers of cardiomyogenesis. Whether and how DCHS2 inhibition protects against pathological hypertrophy or HF are unknown. CAS9 knock-in mice were injected with AAV9 carrying scrambled (control) or guide RNA1 (gRNA1) targeting DCHS2 exon 2 together with troponin T-driven Cre and subjected to transverse aortic construction (TAC). 10 weeks after TAC, DCHS2 knockdown (KD) in CMs reduced heart (HW) and lung weight / tibial length (TL) ratios (HW/TL: 11.14±0.76 vs 13.72±0.72 mg/mm, p=0.04, n=6/group), increased fractional shortening (40.67±3.65% vs 28.80±3.51%, p=0.04, n=6/group) and decreased CM size. DCHS2 KD in CMs increased markers of CM proliferation (Ki67 and pHH3, PCM1 double positive cells, all p&lt;0.05) and expression of mitochondrial respiratory chain complexes I-V protein and PGC1α mRNA (all p&lt;0.05) while attenuating TAC-induced disruption of mitochondrial structure and reactive oxygen species production measured by DHE staining. In primary CMs, DCHS2 gene KD by siRNA increased CM proliferation (13.93±1.09% vs 10.11±0.14%, p=0.03, n=6) which was prevented by Yap1 KD (13.93±1.09% in DCHS2 KD vs 7.45±0.89 in DCHS2/Yap1 double KD, p&lt;0.01, n=6). DCHS2 KD also increased mitochondrial oxygen consumption (354.8±25.86 vs 248.2±10.42 pmol/min, p&lt;0.01, n=6) and enhanced expression of mitochondrial biogenesis-related genes as well as mtDNA copy number (all p&lt;0.05). These DCHS2 KD-induced changes were not affected by Yap1 KD but were canceled by KD of either PGC1α or Acadvl, which is essential for very long chain fatty acids oxidation (all p&lt;0.05). DCHS2 pulldown demonstrated that Acadvl directly bound DHCS2 in CMs. In conclusion, DCHS2 inhibition protects against HF through Yap1-dependent cardiomyogenesis and Acadvl-dependent mitochondrial effects.

Arginase 2 Promotes Cisplatin-Induced Acute Kidney Injury by the Inflammatory Response of Macrophages

Acute kidney injury (AKI) is a complex clinical syndrome with a rapid decrease in renal function caused by several different etiologies, including sepsis, ischemia, and the administration of nephrotoxic drugs. Tubular arginase 2 (ARG2), an arginine-metabolic enzyme, is a potential therapeutic target for AKI, but it has not been confirmed under various AKI conditions. The aim of this study was to investigate ARG2 as a therapeutic target for cisplatin-induced AKI. Cisplatin-treated mice with a genetic deficiency in Arg2 had significant amelioration of renal dysfunction, characterized by decreased acute tubular damage and apoptosis. In contrast, cisplatin-induced tubular toxicity was not ameliorated in proximal tubule cells derived from Arg2-deficient mice. Immunohistochemical analysis demonstrated the increased infiltration of ARG2-positive macrophages in kidneys damaged by cisplatin. Importantly, cisplatin-treated Arg2 knockout mice exhibited a significant reduction in kidney inflammation, characterized by the decreased infiltration of inflammatory macrophages and reduced gene expression of interleukin (IL)-6 and IL-1β. The secretion of IL-6 and IL-1β induced by lipopolysaccharides was decreased in bone marrow–derived macrophages isolated from Arg2-deficient mice. Furthermore, the lipopolysaccharide-induced elevation of mitochondrial membrane potential and production of reactive oxygen species were reduced in bone marrow–derived macrophages lacking Arg2. These findings indicate that ARG2 promotes the inflammatory responses of macrophages through mitochondrial reactive oxygen species, resulting in the exacerbation of AKI. Therefore, targeting ARG2 in macrophages may constitute a promising therapeutic approach for AKI.

FAM210A regulates mitochondrial translation and maintains cardiac mitochondrial homeostasis.

Mitochondria play a vital role in cellular metabolism and energetics and support normal cardiac function. Disrupted mitochondrial function and homeostasis cause a variety of heart diseases. Fam210a (family with sequence similarity 210 member A), a novel mitochondrial gene, is identified as a hub gene in mouse cardiac remodelling by multi-omics studies. Human FAM210A mutations are associated with sarcopenia. However, the physiological role and molecular function of FAM210A remain elusive in the heart. We aim to determine the biological role and molecular mechanism of FAM210A in regulating mitochondrial function and cardiac health in vivo. Tamoxifen-induced αMHCMCM-driven conditional knockout of Fam210a in the mouse cardiomyocytes induced progressive dilated cardiomyopathy and heart failure, ultimately causing mortality. Fam210a deficient cardiomyocytes exhibit severe mitochondrial morphological disruption and functional decline accompanied by myofilament disarray at the late stage of cardiomyopathy. Furthermore, we observed increased mitochondrial reactive oxygen species production, disturbed mitochondrial membrane potential, and reduced respiratory activity in cardiomyocytes at the early stage before contractile dysfunction and heart failure. Multi-omics analyses indicate that FAM210A deficiency persistently activates integrated stress response, resulting in transcriptomic, translatomic, proteomic, and metabolomic reprogramming, ultimately leading to pathogenic progression of heart failure. Mechanistically, mitochondrial polysome profiling analysis shows that FAM210A loss of function compromises mitochondrial mRNA translation and leads to reduced mitochondrial-encoded proteins, followed by disrupted proteostasis. We observed decreased FAM210A protein expression in human ischaemic heart failure and mouse myocardial infarction tissue samples. To further corroborate FAM210A function in the heart, AAV9-mediated overexpression of FAM210A promotes mitochondrial-encoded protein expression, improves cardiac mitochondrial function, and partially rescues murine hearts from cardiac remodelling and damage in ischaemia-induced heart failure. These results suggest that FAM210A is a mitochondrial translation regulator to maintain mitochondrial homeostasis and normal cardiomyocyte contractile function. This study also offers a new therapeutic target for treating ischaemic heart disease.

Melatonin Alleviates Lipopolysaccharide-Induced Endometritis by Inhibiting the Activation of NLRP3 Inflammasome through Autophagy.

Bovine endometritis is characterized by reduced milk production and high rates of infertility. Prior research has indicated that melatonin may possess anti-inflammatory and antioxidant properties that can counteract the progression of inflammatory diseases. In this research, we attempted to elucidate the protective effects of melatonin on LPS-induced endometritis. The results obtained from enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR (qRT-PCR) revealed that melatonin effectively reduced the production and release of pro-inflammatory cytokines in an LPS-induced bovine endometrial epithelial cell line (BEND cells). Furthermore, western blotting demonstrated that melatonin treatment reduced the expression levels of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome-related proteins, including NLRP3, activated caspase-1, and cleaved IL-1β. Importantly, we further demonstrated that the anti-inflammatory effect of melatonin on BEND cells was related to autophagy by western blotting. Moreover, we used western blotting to detect autophagy-related proteins, MitoSOX to detect mitochondrial reactive oxygen species production (mtROS), and mitochondrial membrane potential (MMP) assay to detect mitochondrial membrane potential. The administration of melatonin demonstrated a significant enhancement in autophagy within BEND cells, leading to the effective elimination of impaired mitochondria. This process resulted in a reduction in the generation of reactive oxygen species within the mitochondria, restoration of mitochondrial membrane potential, and inhibition of the NLRP3 inflammasome activation. Moreover, in a mouse model of LPS-induced endometritis, melatonin treatment repressed the expression of pro-inflammatory cytokines by ELISA and qRT-PCR, alleviated pathological changes by hematoxylin-eosin staining (H&E), and inhibited myeloperoxidase (MPO) activity. In conclusion, our study showed that melatonin inhibited the activation of the NLRP3 inflammasome in BEND cells through autophagy, which may provide a novel therapeutic strategy for bovine endometritis.

Glycation derived AuNPs bioconjugated novel herbal drug isoferulic acid: As a potential anti-glycation, anti-diabetic and antineoplastic agent

Based on the significance and impact of serum protein glycation and the possibility that AGEs play a role in diabetes-related complications and cancer, this study examined the anti-glycation, anti-cancer, and α-amylase inhibition activities of isoferulic acid (IFA) and its gold nanoparticle (IFA-AuNPs) bioconjugated formulations. In comparison to the control (glycated) samples, IFA and IFA-AuNPs were found to show a significant reduction in the KM moieties, carbonyl content, and HMF content that were produced during the glycation, demonstrating that the glycation reaction generated less superoxide radicals, had fewer intermediates, and did not cause as many structural perturbations to BSA. The IFA and IFA-AuNPs treated samples had a higher proportion of unreacted lysine and arginine deposits than the control (glycated) samples, suggesting that the inhibitors prevented the association of negatively charged arginine deposits with 2′-Deoxyribose. Purified IFA (IC50 = 4.3 mM) decreased α-amylase activity insignificantly compared to acarbose (IC50 = 0.118 mM). Therefore, IFA may not be suited for targeting α-amylase. However, IFA and its analogs have been reported to inhibit several malignancies, including leukemia, breast, colon, and lung cancer. Therefore, the cytotoxicity study was conducted using human keratinocytes (HaCat cells), and the IC50 values for IFA and IFA-AuNPs were determined to be 6062.4 µM and 151.6 µM, respectively. Their cytotoxic effects on human lung cancer epithelial cells (A549), however, were estimated to be 5593 µM and 117.5 µM. Our study confirmed that IFA-treated A549 cells at a greater concentration (5593 µM) caused less disruption of mitochondrial membrane potential (ΔΨm) and production of ROS burst than IFA-AuNPs at a significantly lower concentration (117,5 µM). When ΔΨm was disrupted, Cyt-c-mediated apoptosis was elicited, which then allowed IFA and AuNPs to work synergistically to degrade DNA. It was discovered that IFA-AuNPs target cancer cells through different pathways, with AuNPs potentiating the effect of IFA.

In vivo measurement of mitochondrial ROS production in mouse models of photoreceptor degeneration

Retinitis pigmentosa (RP) is a disease characterised by photoreceptor cell death. It can be initiated by mutations in a number of different genes, primarily affecting rods, which will die first, resulting in loss of night vision. The secondary death of cones then leads to loss of visual acuity and blindness. We set out to investigate whether increased mitochondrial reactive oxygen species (ROS) formation, plays a role in this sequential photoreceptor degeneration. To do this we measured mitochondrial H2O2 production within mouse eyes in vivo using the mass spectrometric probe MitoB. We found higher levels of mitochondrial ROS that preceded photoreceptor loss in four mouse models of RP: Pde6brd1/rd1; Prhp2rds/rds; RPGR−/−; Cln6nclf. In contrast, there was no increase in mitochondrial ROS in loss of function models of vision loss (GNAT−/−, OGC), or where vision loss was not due to photoreceptor death (Cln3). Upregulation of Nrf2 transcriptional activity with dimethylfumarate (DMF) lowered mitochondrial ROS in RPGR−/− mice. These findings have important implications for the mechanism and treatment of RP.