Mitochondrial Respiratory Chain Research Articles

Endurance exercise attenuates Gαq-RNAi induced hereditary obesity and skeletal muscle dysfunction via improving skeletal muscle Srl/MRCC-I pathway in Drosophila.

G protein alpha q subunit (Gαq) can binds to the G protein-coupled receptor (GPCR) for signaling and is closely related to lipid metabolism. Endurance exercise is an effective means of combating acquired obesity and its complications, but the mechanisms by which endurance exercise modulates hereditary obesity and its complications are unknown. In this study, we achieved knockdown of Gαq in drosophila adipose tissue and skeletal muscle by constructing the Gαq-UAS-RNAi/Ppl-Gal4 and Gαq-UAS-RNAi/Mef2-GAl4 systems. Drosophila were subjected a three-week endurance exercise intervention, and changes in relevant indicators were detected and observed by RT-PCR, ELISA, oil red staining, immunofluorescence staining, and transmission electron microscopy. The results showed that knockdown of Gαq in both adipose tissue and skeletal muscle induced a significant increase in triglycerides accompanied by a decrease in rapid climbing ability, a decrease in Superoxide Dismutase (SOD) activity level, and a decrease in Mitochondrial respiratory chain complexI (MRCC I) content in Drosophila whole body and skeletal muscle, and down-regulated the expression of the G protein alpha q subunit (Gαq), the skeletal muscle myosin heavy chain expression gene (Mhc), mitochondrial biogenesis gene Spargal(the PGC-1alpha homologue in Drosophila). Endurance exercise significantly improved the triglyceride levels in the whole body and skeletal muscle of drosophila with Gαq knockdown in adipose tissue and skeletal muscle, as well as their ability to climb, increased SOD activity level and MRCCI content level, and up-regulated the expression of Gαq, Mhc, and Spargal(Srl). Thus, the present findings suggest that genetic defects in the Gαq gene in adipose and skeletal muscle tissues induce hereditary obesity and skeletal muscle dysfunction, and that endurance exercise attenuates this hereditary obesity and concomitant skeletal muscle dysfunction in drosophila by improving skeletal muscle fiber contractile proteins, mitochondrial function and function, and antioxidant capacity via mediating the Gαq/Mhc, Gαq/Srl/MRCC-I, and Gαq/SOD pathways.

INFLUENCE OF SODIUM GLUTAMATE ON REACTIVE OXYGEN AND NITROGEN SPECIES PRODUCTION IN KIDNEY TISSUES OF RATS UNDER ACUTE DESYNCHRONIZATION AND LIPOPOLYSACCHARIDE-INDUCED SYSTEMIC INFLAMMATORY RESPONSE

The study investigated the effect of sodium glutamate on the production of reactive oxygen and nitrogen species (ROS/RNS) in kidney tissues of rats under conditions of acute desynchronization (AD) and lipopolysaccharide (LPS)-induced systemic inflammatory response (SIR) and, thus, contributed to a deeper understanding of the mechanisms involved in the development of renal dysfunction under these conditions. The experiment was conducted on 21 male Wistar rats (210-230 g), randomly divided into three groups: intact animals, a group exposed to AD modeling under LPS-induced systemic inflammatory response (Group II), and a group (Group 3) exposed to AD modeling under LPS-induced systemic inflammatory response, who received sodium glutamate in a dose of 20 mg/kg. The administration of sodium glutamate significantly increased the generation rate of the superoxide anion radical by 13.8% through microsomal monooxygenases, by 8.7% through the mitochondrial respiratory chain, and by 7.7% through leukocyte NADPH oxidase compared to Group 2. However, sodium glutamate did not affect the total NO synthase activity or the activity of its constitutive and inducible isozymes in the kidney homogenate compared to Group 2. The uncoupling index of constitutive NO synthases in kidney tissues also remained unchanged under the administration of sodium glutamate, but the peroxynitrites were 20.5% higher, and S-nitrosothiols were 11.6% higher, than in group 2. The findings indicate that sodium glutamate significantly increases oxidative-nitrosative stress in rat kidney tissues under AD and LPS-induced SIR, resulting in excessive ROS/RNS formation.

Shock wave-pretreated ADMSCs of cell-sheet scaffold (CSS) patched on left ventricular wall (LVW) inhibited LVW remodeling in mini-pig MI ---role CSS on counteracting Laplace's Law of LVW stress: Experimental study.

We investigated whether shock wave (SW)-pretreated autologous adipocyte-derived mesenchymal stem cells (ADMSCs) seeded in the cell-sheet scaffold (CSS) could inhibit left ventricular (LV) remodeling and improve LV ejection fraction (LVEF) in old myocardial infarction (MI). Mini-pigs (n=20) were divided into group 1 (sham-operated control), group 2 (old MI), group 3 (old MI + autologous ADMSCs/1.0×107 in CSS on LV myocardium), and group 4 [old MI + SW (0.12mJ/mm2 for total 140 shots)-pretreated ADMSCs in CSS on LV myocardium]. Treatments started on day 28 after MI induction. In vivo and in vitro studies were conducted. Cell viability/relative mitochondria DNA expression/mitochondrial cytochrome C/adenosine triphosphate concentration in ADMCSs and protein expressions of angiogenesis factors (vascular endothelial growth factor [VEGF]/stromal cell-derived factor-1 [SDF-1])/mitochondrial respiratory chain complexes I-IV/oxygen consumption rate were higher in group 4 than in group 3 (P<0.001). By day 180, LVEF and small vessel numbers in the peri-infarct or infarct area were highest in group 1, lowest in group 2, and significantly lower in group 3 than in group 4. In contrast, the LV dimension was opposite to the pattern of change in LVEF in all groups (P<0.0001). The basal/middle/apical infarct and fibrotic areas were inversely related to LVEF in all groups (all P<0.0001). Protein levels of angiogenetic markers (SDF-1α/C-X-C chemokine receptor type 4/VEGF/angiopoietin-1) were significantly and persistently increased from groups 1 to 4. In contrast, protein levels of endothelial-cell markers (von Willebrand factor or endothelial nitric oxide synthase) showed an identical pattern to LVEF in all groups (all P<0.0001). SW pretreatment of ADMSCs seeded in CSS offered significant benefits in preserving LV performance and ameliorating LV remodeling in mini-pigs with old MI.

Sex Differences in Response to Diet Enriched with Glutathione Precursors in the Aging Heart.

Common features of the aging heart are dysregulated metabolism, inflammation, and fibrosis. Elevated oxidative stress is another hallmark of cardiac aging that can exacerbate each of these conditions. We hypothesize that by increasing natural antioxidant levels (glutathione), we will improve cardiac function. Twenty-one-month-old mice were fed Glycine and N-Acetyl Cysteine (GlyNAC) (glutathione precursors)-supplemented or control diets for 12 weeks. Heart function was monitored longitudinally, and the exercise performance was determined at the end of the study. We found that the GlyNAC diet was beneficial for old male but not old female mice, leading to an increase of Ndufb8 expression (a subunit of the mitochondrial respiratory chain complex), and higher enzymatic activity for CPT1b and CrAT, two carnitine acyltransferases that are critical to cardiomyocyte metabolism. Although no quantifiable change of collagen turnover was detected, hearts from GlyNAC-fed old males exhibited a slight but significant enrichment in Fmod, a protein that can inhibit collagen fibril formation, possibly reducing extracellular matrix (ECM) stiffness and thus improving diastolic function. Cardiac diastolic function was modestly improved in males but not females, and surprisingly GlyNAC-fed female mice showed a decline in exercise performance. In summary, our work supports the concept that aged male and female hearts are phenotypically different. These basic differences may affect the response to pharmacological and diet interventions, including antioxidants.

A promising drug repurposing approach for Alzheimer's treatment: Givinostat improves cognitive behavior and pathological features in APP/PS1 mice.

Alzheimer’s disease (AD) is the most common neurodegenerative disease, characterized by memory loss, speech and motor defects, personality changes, and psychological disorders. The exact cause of AD remains unclear. Current treatments focus on maintaining neurotransmitter levels or targeting β-amyloid (Aβ) protein, but these only alleviate symptoms and do not reverse the disease. Developing new drugs is time-consuming, costly, and has a high failure rate. Utilizing multi-omics for drug repositioning has emerged as a new strategy. Based on transcriptomic perturbation data of over 40,000 drugs in human cells from the LINCS-L1000 database, our study employed the Jaccard index and hypergeometric distribution test for reverse transcriptional feature matching analysis, identifying Givinostat as a potential treatment for AD. Our research found that Givinostat improved cognitive behavior and brain pathology in models and enhanced hippocampal synaptic plasticity. Transcriptome sequencing revealed increased expression of mitochondrial respiratory chain complex proteins in the brains of APP/PS1 mice after Givinostat treatment. Functionally, Givinostat restored mitochondrial membrane potential, reduced reactive oxygen species, and increased ATP content in Aβ-induced HT22 cells. Additionally, it improved mitochondrial morphology and quantity in the hippocampus of APP/PS1 mice and enhanced brain glucose metabolic activity. These effects are linked to Givinostat promoting mitochondrial biogenesis and improving mitochondrial function. In summary, Givinostat offers a promising new strategy for AD treatment by targeting mitochondrial dysfunction.

Mitochondrial inhibitors reveal roles of specific respiratory chain complexes in CRY-dependent degradation of TIM

Drosophila Cryptochrome (CRY) is an essential photoreceptor that mediates the resetting of the circadian clock by light. in vitro studies demonstrated a critical role of redox cycling of the FAD cofactor for CRY activation by light. However, it is unknown if CRY responds to cellular redox environment to modulate the circadian clock. We report here that the mitochondrial respiratory chain impinges on CRY activity. Inhibition of complex III and V blocks CRY-mediated degradation of TIMELESS (TIM) in response to light, and also blocks light-induced CRY degradation. On the other hand, inhibition of complex I facilitates TIM degradation even in the dark. Mutations of critical residues of the CRY C-terminus promote TIM degradation in the dark, even in the presence of complex III and V inhibitors. We propose that complex III and V activities are important for activation of CRY in response to light. Interestingly, we found that transcriptional repressor functions of Drosophila and mammalian CRY proteins are not affected by mitochondrial inhibitors. Together these data suggest that the two functions of CRY have different sensitivity to disruptions of the mitochondrial respiratory chain: one is sensitive to mitochondrial activities that enable resetting, the other is insensitive so as to sustain the molecular oscillator.

Distinct Essentiality of the Mitochondrial Respiratory Chain in Proliferating Cells in Vivo

Mitochondrial respiratory chain (RC) activity is essential for in vivo cell proliferation, particularly in cancer, CD4+ and CD8+ T cells, and endothelial cells involving ATP production and biosynthesis. The RC is essential for the oxidative tricarboxylic acid (TCA) cycle to produce intermediates that funnel into anabolic pathways to synthesize lipids, proteins, and nucleotides. By contrast, mitochondrial respiration has a distinct role in other proliferating cells including regulatory T cells (Tregs) and stem cells whereby mitochondria are dispensable for in vivo cell proliferation but determine cell fate and function through several signaling mechanisms. In this review, we discuss how the mitochondrial RC is an anabolic engine that supports the proliferation of cancer cells, CD4+ and CD8+ T cells, and endothelial cells while mitochondria serve as central hubs that integrate metabolic signals to control Treg and stem cell fate and function in vivo.

Alda-1 Ameliorates Oxidative Stress-Induced Cardiomyocyte Damage by Inhibiting the Mitochondrial ROS/TXNIP/NLRP3 Pathway.

Alda-1 functions as an agonist of aldehyde dehydrogenase (ALDH2) within the mitochondria, contributing to the preservation of mitochondrial structure and function. This study aimed to determine whether Alda-1 inhibited the accumulation of mitochondrial reactive oxygen species (mtROS) and improved cardiomyocyte damage under oxidative stress. Cardiomyocytes derived from human induced pluripotent embryonic stem cells (iPSC-CMs) and human AC16 cardiomyocytes were chosen for the experiments. Oxidative stress was induced in both cardiomyocyte types using hydrogen peroxide (H2O2), a commonly employed agent. The mtROS accumulation and mitochondrial functional status were assessed by measuring the ROS content, mitochondrial membrane potential, and mitochondrial respiratory chain function. Co-IP experiments were used to analyze whether mtROS promoted protein interactions between TXNIP and NLRP3 and induced NLRP3 inflammasome activation. The results showed that Alda-1 mitigated damage to mitochondrial structure and function under oxidative stress, concurrently reducing the accumulation of mtROS. Co-IP experiments revealed that elevated mtROS levels attenuated the protein interaction between TXNIP and TRX while intensifying the interaction between TXNIP and NLRP3. Consequently, this triggers activation of the NLRP3 inflammasome, leading to cardiomyocyte damage. In contrast, TXNIP knockdown inhibited H2O2-induced myocardial injury and enhanced the therapeutic effects of Alda-1. Collectively, the results show that, in an H2O2 environment, Alda-1 increased the production of ALDH2 activity in cardiomyocytes, hindered the production of mtROS, disrupted the interaction between TXNIP and NLRP3, and alleviated myocardial damage during oxidative stress.

Multi-omics landscape and molecular basis of radiation tolerance in a tardigrade.

Tardigrades are captivating organisms known for their resilience in extreme environments, including ultra-high-dose radiation, but the underlying mechanisms of this resilience remain largely unknown. Using genome, transcriptome, and proteome analysis of Hypsibius henanensis sp. nov., we explored the molecular basis contributing to radiotolerance in this organism. A putatively horizontally transferred gene, DOPA dioxygenase 1 (DODA1), responds to radiation and confers radiotolerance by synthesizing betalains-a type of plant pigment with free radical-scavenging properties. A tardigrade-specific radiation-induced disordered protein, TRID1, facilitates DNA damage repair through a mechanism involving phase separation. Two mitochondrial respiratory chain complex assembly proteins, BCS1 and NDUFB8, accumulate to accelerate nicotinamide adenine dinucleotide (NAD+) regeneration for poly(adenosine diphosphate-ribosyl)ation (PARylation) and subsequent poly(adenosine diphosphate-ribose) polymerase 1 (PARP1)-mediated DNA damage repair. These three observations expand our understanding of mechanisms of tardigrade radiotolerance.

Neonatal Hemochromatosis Secondary to an Inborn Error of Metabolism (Mitochondrial Disorder): Post- mortem Diagnosis in the Fetus of a Young Primipara

Abstract Introduction/Objective Neonatal hemochromatosis (NH), an extremely rare congenital phenotype of acute hepatic failure with hepatic and extrahepatic siderosis, is primarily (98%) caused by gestational alloimmune liver disease (GALD) and, rarely (2%), by infection, metabolic disorders, bile acid defects, and mitochondrial hepatopathy. This report presents an extremely rare case of NH caused by an inborn error of metabolism (suspected mitochondrial dysfunction). This low-birth-weight female was born with acute liver failure, metabolic acidosis, multisystem failure, and progressive lactate acidosis, and expired on day 7. On autopsy, liver was less than 50% of normal size and without nodularity. Microscopic architecture was preserved with erythropoiesis, canalicular bile plugs, microvesicular steatosis (oil red O stain) and abundant coarsely granular siderosis (iron stain). GALD was unlikely because of the absence of the typical hepatocytic injury, fibrosis or biliary destruction, and the negative immunohistochemistry for MAC (C5b-C9). Extrahepatic siderosis was demonstrated in thyroid follicles, thymic Hassall corpuscles, myocardium, and adenohypophysis. Sanger sequencing and deletion testing of mitochondrial genome on a maternal buccal biopsy identified a homoplasmic variant (m.15482 T&amp;gt;C p.(S246P) in maternal MT-CYB gene but without molecular diagnosis of a mitochondrial DNA disorder. Infant plasma had increased C6DC, C5, C12-OH acylcarnitine, alanine, and proline. Urine contained elevated organic acids (lactate/pyruvate, 2-ketoacids, 3-methylglutarate, 3-methylglutaconate), concerning acute mitochondrial respiratory chain dysfunction. Methods/Case Report: Case Study Results (if a Case Study enter NA) NA Conclusion Diagnosis of NH warrants exclusion of the most common etiology, GALD. Mitochondrial genetic mutations are the most difficult to diagnosis because of heterogeneity and typically undiagnosed maternal defects. This is the first report of NH with a homoplasmic maternal variant of uncertain significance. Neonatal lactic acidosis is the strongest clinical clue for mitochondrial dysfunction and should trigger phenotyping, maternal mitochondrial genetic variants (mtDNA, nuDNA), functional, biochemical, and genetic studies.

Hepatocyte-derived Igκ promotes HCC progression by stabilizing electron transfer flavoprotein subunit α to facilitate fatty acid β-oxidation

BackgroundLipid metabolism dysregulation is a key characteristic of hepatocellular carcinoma (HCC) onset and progression. Elevated expression of immunoglobulin (Ig), especially the Igκ free light chain with a unique Vκ4-1/Jκ3 rearrangement in cancer cells, is linked to increased malignancy and has been implicated in colon cancer tumorigenesis. However, the role of Igκ in HCC carcinogenesis remains unclear. The aim of this study was to elucidate the pivotal roles of hepatocyte-derived Igκ in HCC development.MethodsThe rearrangement sequence and expression level of hepatocyte-derived Igκ in HCC cells were determined via RT-PCR, Sanger sequencing, immunohistochemistry, and western blot analysis. The function of Igκ in HCC tumorigenesis was assessed by silencing Igκ using siRNA or gRNA in various HCC cell lines. To assess the role of Igκ in HCC pathogenesis in vivo, a mouse model with hepatocyte-specific Igκ knockout and diethylnitrosamine (DEN) and carbon tetrachloride (CCL4)-induced HCC was utilized. The molecular mechanism by which Igκ affects HCC tumorigenesis was investigated through multiomics analyses, quantitative real-time PCR, immunoprecipitation, mass spectrometry, immunofluorescence, and metabolite detection.ResultsWe confirmed that Igκ, especially Vκ4-1/Jκ3-Igκ, is highly expressed in human HCC cells. Igκ depletion inhibited HCC cell proliferation and migration in vitro, and hepatocyte-specific Igκ deficiency ameliorated HCC progression in mice with DEN and CCL4-induced HCC in vivo. Mechanistically, Vκ4-1/Jκ3-Igκ interacts with electron transfer flavoprotein subunit α (ETFA), delaying its protein degradation. Loss of Igκ led to a decrease in the expression of mitochondrial respiratory chain complexes III and IV, resulting in aberrant fatty acid β-oxidation (FAO) and lipid accumulation, which in turn inhibited HCC cell proliferation and migration.ConclusionOur findings indicate that the Igκ/ETFA axis deregulates fatty acid β-oxidation, contributing to HCC progression, which suggests that targeting fatty acid metabolism may be an effective HCC treatment strategy. The results of this study suggest that hepatocyte-derived Vκ4-1/Jκ3-Igκ may serve as a promising therapeutic target for HCC.

Growth, Morphology and Respiratory Cost Responses to Salinity in the Mangrove Plant Rhizophora Stylosa Depend on Growth Temperature.

Mangrove plants, which have evolved to inhabit tidal flats, may adjust their physiological and morphological traits to optimize their growth in saline habitats. Furthermore, the confined distribution of mangroves within warm regions suggests that warm temperature is advantageous to their growth in saline environments. We analyzed growth, morphology and respiratory responses to moderate salinity and temperature in a mangrove species, Rhizophora stylosa. The growth of R. stylosa was accelerated in moderate salinity compared with its growth in fresh water. Under warm conditions, the increased growth is accompanied by increased specific leaf area (SLA) and specific root length. Low temperature resulted in a low relative growth rate due to a low leaf area ratio and small SLA, regardless of salinity. Salinity lowered the ratio of the amounts of alternative oxidase to cytochrome c oxidase in the mitochondrial respiratory chain in leaves. Salinity enhanced the leaf respiration rate for maintenance, but under warm conditions this enhancement was compensated by a low leaf respiration rate for growth. In contrast, salinity enhanced overall leaf respiration rates at low temperature. Our results indicate that under moderate saline conditions R. stylosa leaves require warm temperatures to grow with a high rate of resource acquisition without enhancing respiratory cost.

7086 Disrupted Mitochondrial Function in Alström Syndrome- A Monogenic Model of Insulin Resistance and Obesity

Abstract Disclosure: S. Ali: None. S. Heising: None. V. Veeranna: None. A. Vincent: None. G.S. Xavier: None. T. Geberhiwot: None. Alström syndrome (ALMS) is a rare monogenic disease typified by severe insulin resistance (IR) and obesity. IR and obesity are cardinal features of metabolic syndrome. The metabolic effects of insulin at key target tissues leads to metabolic haemostasis by promoting glucose and lipid uptake and metabolism to generate energy in cells. Although insulin is a major regulator of fuel metabolism, its effects on mitochondrial ATP production in severe insulin resistance are unclear. RNASeq data from adipose tissue (AT) from patients with ALMS show downregulation of the expression of genes associated with mitochondrial respiratory chain function, pointing towards possible altered mitochondrial function in ALMS. We therefore undertook a detailed assessment of mitochondrial oxidative phosphorylation capacity (OXPHOS) in skeletal muscle (SM) in ALMS. We performed SM biopsy in 10 ALMS and 10 healthy control volunteers that were age, gender and Body Mass Index matched. The SM was subjected to high resolution respirometry, the gold standard method to quantify mitochondrial function ex vivo, using OROBOROS Oxygraph -2k (O2k) system. Overall OXPHOS was higher in control SM compared to ALMS, with maximal respiration of 62.96±19.2 and 44.24 ± 12.53 pmol/(s*mg), respectively (p&amp;lt;0.05).Reduced oxygen influx was observed in ALMS SM in comparison to controls for fatty acid ß oxidation (6.7±5.96 vs 7.87±2.7 pmol/(s*mg);p&amp;lt;0.05, at complex I (19.4 ± 8.98 vs 29.7 ±5.3 pmol/(s*mg);p&amp;lt;0.05, and at complex II (34.98 ±11.75 vs 53.52± 13.2 pmol/(s*mg) ;p&amp;lt;0.05. Mitochondrial membrane integrity was unaffected during these experiments. Therefore, our analysis unveils a consistent reduction in mitochondrial respiration across all the electron transport pathway. This noteworthy finding suggests impairment in respiratory function and the electron transport chain in mitochondria, a crucial aspect of cellular energy metabolism. Several studies have previously linked IR with mitochondrial dysfunction, where insulin-resistant rodents and humans have shown blunted mitochondrial response to ATP generation. Our results align with this body of evidence emphasizing the significance of investigating the underlying mechanism contributing to this phenomenon. These findings could pave the way to exploring potential mitochondrial-targeted therapies to restore mitochondrial function and therefore, improve insulin sensitivity to tackle IR in ALMS. Presentation: 6/2/2024

Systemic messenger RNA replacement therapy is effective in a novel clinically relevant model of acute intermittent porphyria developed in non-human primates

ObjectiveAcute intermittent porphyria (AIP) is a rare metabolic disorder caused by haploinsufficiency of hepatic porphobilinogen deaminase (PBGD), the third enzyme of the heme biosynthesis. Individuals with AIP experience neurovisceral attacks...

Synergistic Gas Therapy and Targeted Interventional Ablation With Size-Controllable Arsenic Sulfide (As2S3) Nanoparticles for Effective Elimination of Localized Cancer Pain.

The elimination of localized cancer pain remains a globally neglected challenge. A potential solution lies in combining gas therapy with targeted interventional ablation therapy. In this study, HA-As2S3 nanoparticles with controlled sizes are synthesized using different molecular weights of sodium hyaluronate (HA) as a supramolecular scaffold. Initially, HA co-assembles with arsenic ions (As3+) via coordinate bonds, forming HA-As3+ scaffold intermediates. These intermediates, varying in size, then react with sulfur ions to produce size-controlled HA-As2S3 particles. This approach demonstrates that different molecular weights of HA enable precise control over the particle size of arsenic sulfide, offering a straightforward and environmentally friendly method for synthesizing metal sulfide particles. In an acidic environment, HA-As2S3 nanoparticles release hydrogen sulfide(H2S) gas and As3+. The released As3+ directly damage tumor mitochondria, leading to substantial reactive oxygen species (ROS) production from mitochondria. Concurrently, the H2S gas inhibits the activity of catalase (CAT) and complex IV, preventing the beneficial decomposition of ROS and disrupting electron transfer in the mitochondrial respiratory chain. Consequently, it is found that H2S gas significantly enhances the mitochondrial damage induced by arsenic nanodrugs, effectively killing local tumors and ultimately eliminating cancer pain in mice.

Effects of microbe-derived antioxidants on growth performance, hepatic oxidative stress, mitochondrial function and cell apoptosis in weaning piglets

BackgroundWeaning causes redox dyshomeostasis in piglets, which leads to hepatic oxidative damage. Microbe-derived antioxidants (MA) have great potential for anti-oxidation. This study aimed to investigate changes in hepatic redox system, mitochondrial function and apoptosis after weaning, and effects of MA on growth performance and liver health in weaning piglets.MethodsThis study consisted of 2 experiments. In the both experiments, piglets were weaned at 21 days of age. In Exp. 1, at 21 (W0), 22 (W1), 25 (W4), 28 (W7), and 35 (W14) days of age, 6 piglets were slaughtered at each timepoint. In Exp. 2, piglets were divided into 2 groups: one received MA gavage (MA) and the other received saline gavage (CON). At 25 days of age, 6 piglets from each group were sacrificed.ResultsIn Exp. 1, weaning caused growth inhibition and liver developmental retardation from W0 to W4. The mRNA sequencing between W0 and W4 revealed that pathways related to “regulation of apoptotic process” and “reactive oxygen species metabolic process” were enriched. Further study showed that weaning led to higher hepatic content of reactive oxygen species (ROS), H2O2 and O2−. Weaning enhanced mitochondrial fission and suppressed their fusion, activated mitophagy, thus triggering cell apoptosis. In Exp. 2, MA improved growth performance of piglets with higher average daily gain (ADG) and average daily feed intake (ADFI). The hepatic ROS, as well as products of oxidative damage malonaldehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) in the MA group decreased significantly than that of the CON group. The MA elevated mitochondrial membrane potential, increased activity of mitochondrial respiratory chain complexes (MRC) I and IV, enhanced mitochondrial fusion and reduced mitophagy, thus decreasing cell apoptosis.ConclusionsThe present study showed that MA improved the growth performance of weaning piglets and reversed weaning-induced oxidative damage, mitochondrial dysfunction, and apoptosis. Our results suggested that MA had promising prospects for maintaining liver health in weaning piglets and provided a reference for studies of liver diseases in humans.Graphical

The tolerable upper intake level of manganese alleviates Parkinson-like motor performance and neuronal loss by activating mitophagy

Manganese (Mn2+) is among the indispensable trace elements required by the human body, but high-dose Mn2+ exposure can lead to Mn poisoning. Therefore, the tolerable upper intake level (UL) for Mn2+ has been established for normal individuals in different countries. However, whether the UL of Mn2+ is suitable for the patients of Parkinson's disease (PD) is unclear.Here, we found unexpectedly that the dietary UL of Mn2+ supplement enhanced mitophagy through the PINK1/parkin-mediated ubiquitin-dependent pathway in MPTP- induced mice and cells. Mn2+ promoted mitochondrial biogenesis and dynamics, thereby increased the activity of the mitochondrial respiratory chain with restored mitochondrial function. Additionally, Mn2+ directly elevated the activity of mitochondrial superoxide dismutase (MnSOD), which contributed to the clearance of reactive oxygen species (ROS), restored dopaminergic and motor functions in the MPTP-induced PD mouse model. Similar results were also observed in SH-SY5Y cells, whereas knockdown parkin using siRNA or application of mitophagy inhibitors (Mdivi-1 or cyclosporine A), abolished the neuroprotective effects of Mn2+.These findings demonstrate that the dietary UL of Mn2+ is protective for the MPTP-induced Parkinson-like lesions with the mechanisms involving the activation of mitophagy, suggesting potential intervention of PD by moderately increasing dietary Mn2+ intake.

Isovalerylspiramycin I suppresses small cell lung cancer proliferation via ATR/CHK1 mediated DNA damage response and PERK/eIF2α/ATF4/CHOP mediated ER stress

Small cell lung cancer (SCLC) urgently needs new therapeutic approaches. We found that the antibiotic-derived compound Isovalerylspiramycin I (ISP-I) has potent anti-tumor activity against SCLC cell lines H1048 and DMS53 both in vitro and in vivo. ISP-I induced apoptosis, G2/M phase cell cycle arrest, and mitochondrial respiratory chain dysfunction in both cell lines. Comprehensive RNA sequencing revealed that the anti-SCLC effects of ISP-I were primarily attributed to ATR/CHK1-mediated DNA damage response and PERK/eIF2α/ATF4/CHOP-mediated ER stress. Importantly, the induction of DNA damage, ER stress, and apoptosis by ISP-I was mitigated by the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC), underscoring the critical role of ROS in the anti-SCLC mechanism of ISP-I. Moreover, ISP-I treatment induced immunogenic cell death (ICD) in SCLC cells, as evidenced by increased adenosine triphosphate (ATP) secretion, elevated release of high-mobility group box 1 (HMGB1), and enhanced exposure of calreticulin (CRT) on the cell surface. Additionally, network pharmacology analysis, combined with cellular thermal shift assay (CETSA) and cycloheximide (CHX) chase experiments, demonstrated that ISP-I acted as a ligand for apurinic/apyrimidinic endonuclease 1 (APEX1) and promoted its degradation, leading to the accumulation of ROS. In conclusion, our findings elucidate the multifaceted mechanisms underlying the anti-cancer effects of ISP-I, highlighting its potential as a promising therapeutic candidate for SCLC treatment.

FGF21 inhibits ferroptosis caused by mitochondrial damage to promote the repair of peripheral nerve injury.

Ferroptosis is a new type of cell death characterized by lipid peroxidation and iron dependency, representing an emerging disease regulation mechanism. The limited understanding of ferroptosis in peripheral nerve injury (PNI) complicates the management of such injuries. Mitochondrial dysfunction, which contributes to ferroptosis, further exacerbates the challenges of peripheral nerve repair. In this study, we established an in vitro model of Schwann cells model treated with TBHP and an in vivo sciatic nerve crush injury model in rats. These models were used to investigate the effects of fibroblast growth factor 21 (FGF21) on PNI, both in vitro and in vivo, and to explore the potential mechanisms linking injury-induced ferroptosis and mitochondrial dysfunction. Our findings reveal that PNI triggers abnormal accumulation of lipid reactive oxygen species (ROS) and inactivates mitochondrial respiratory chain complex III, leading to mitochondrial dysfunction. This dysfunction catalyzes the oxidation of excessive polyunsaturated fatty acids, resulting in antioxidant imbalance and loss of ferroptosis suppressor protein 1 (FSP1), which drives lipid peroxidation. Additionally, irregular iron metabolism, defective mitophagy, and other factors contribute to the induction of ferroptosis. Importantly, we found that FGF21 attenuates the abnormal accumulation of lipid ROS, restores mitochondrial function, and suppresses ferroptosis, thus promoting PNI repair. Notably, glutathione peroxidase 4 (GPX4), a downstream target of nuclear factor E2-related factor 2 (Nrf2), and the ERK/Nrf2 pathway are involved in the regulation of ferroptosis by FGF21. FGF21 promotes peripheral nerve repair by inhibiting ferroptosis caused by mitochondrial dysfunction. Therefore, targeting mitochondria and ferroptosis represents a promising therapeutic strategy for effective PNI repair.

Characterization of Shy1, the Schizosaccharomyces pombe homolog of human SURF1

Cytochrome c oxidase (complex IV) is the terminal enzyme in the mitochondrial respiratory chain. As a rare neurometabolic disorder caused by mutations in the human complex IV assembly factor SURF1, Leigh Syndrome (LS) is associated with complex IV deficiency. In this study, we comprehensively characterized Schizosaccharomyces pombe Shy1, the homolog of human SURF1. Bioinformatics analysis revealed that Shy1 contains a conserved SURF1 domain that links to the biogenesis of complex IV and shares high structural similarity with its homologs in Saccharomyces cerevisiae and humans. Our study showed that Shy1 is required for the expression of mtDNA-encoded genes and physically interacts with structural subunits and assembly factors of complex IV. Interestingly, Rip1, the subunit of ubiquinone-cytochrome c oxidoreductase or cytochrome bc1 complex (complex III), can also co-immunoprecipitate with Shy1, suggesting Shy1 may be involved in the assembly of the mitochondrial respiratory chain supercomplexes. This conclusion is further corroborated by our BN-PAGE analysis. Unlike its homologs, deletion of shy1 does not critically disrupt respiratory chain assembly, indicating the presence of the compensatory mechanism(s) within S. pombe that ensure mitochondrial functionality. Collectively, our investigation elucidates that Shy1 plays a pivotal role in the sustainability of the regular function of mitochondria by participating in the assembly of complex IV in S. pombe.