Mitochondrial Respiratory Chain Research Articles

Heat stress upregulates arachidonic acid to trigger autophagy in sertoli cells via dysfunctional mitochondrial respiratory chain function

As a key factor in determining testis size and sperm number, sertoli cells (SCs) play a crucial role in male infertility. Heat stress (HS) reduces SCs counts, negatively impacting nutrient transport and supply to germ cells, and leading to spermatogenesis failure in humans and animals. However, how HS affects the number of SCs remains unclear. We hypothesized that changes in SC metabolism contribute to the adverse effects of HS. In this study, we first observed an upregulation of arachidonic acid (AA), an unsaturated fatty acid after HS exposure by LC-MS/MS metabolome detection. By increasing ROS levels, expression of KEAP1 and NRF2 proteins as well as LC3 and LAMP2, 100 µM AA induced autophagy in SCs by activating oxidative stress (OS). We observed adverse effects of AA on mitochondria under HS with a decrease of mitochondrial number and an increase of mitochondrial membrane potential (MMP). We also found that AA alternated the oxygen transport and absorption function of mitochondria by increasing glycolysis flux and decreasing oxygen consumption rate as well as the expression of mitochondrial electron transport chain (ETC) proteins Complex I, II, V. However, pretreatment with 5 mM NAC (ROS inhibitor) and 2 µM Rotenone (mitochondrial ETC inhibitor) reversed the autophagy induced by AA. In summary, AA modulates autophagy in SCs during HS by disrupting mitochondrial ETC function, inferring that the release of AA is a switch-like response, and providing insight into the underlying mechanism of high temperatures causing male infertility.

Fmo induction as a tool to screen for pro-longevity drugs.

Dietary restriction (DR) and hypoxia (low oxygen) extend lifespan in Caenorhabditis elegans through the induction of a convergent downstream longevity gene, fmo-2. Flavin-containing monooxygenases (FMOs) are highly conserved xenobiotic-metabolizing enzymes with a clear role in promoting longevity in nematodes and a plausible similar role in mammals. This makes them an attractive potential target of small molecule drugs to stimulate the health-promoting effects of longevity pathways. Here, we utilize an fmo-2 fluorescent transcriptional reporter in C. elegans to screen a set of 80 compounds previously shown to improve stress resistance in mouse fibroblasts. Our data show that 19 compounds significantly induce fmo-2, and 10 of the compounds induce fmo-2 more than twofold. Interestingly, 9 of the 10 high fmo-2 inducers also extend lifespan in C. elegans. Two of these drugs, mitochondrial respiration chain complex inhibitors, interact with the hypoxia pathway to induce fmo-2, whereas two dopamine receptor type 2 (DRD2) antagonists interact with the DR pathway to induce fmo-2, indicating that dopamine signaling is involved in DR-mediated fmo-2 induction. Together, our data identify nine drugs that each (1) increase stress resistance in mouse fibroblasts, (2) induce fmo-2 in C. elegans, and (3) extend nematode lifespan, some through known longevity pathways. These results define fmo-2 induction as a viable approach to identifying and understanding mechanisms of putative longevity compounds.

#1546 Mitochondrial oxidative phosphorylation in human proximal tubular epithelial cells is impaired by iron deficiency

Abstract Background and Aims We recently reported that iron deficiency may precede decline in renal function in patients with diabetes who had normal renal function at baseline but had a subsequent annual rate of eGFR decline of 3.3% or more (J Diabetes Investig. 2023;14:874-882.). Mitochondria contain many mitochondrial respiratory chain (MRC) enzymes that require iron as an active center, and consequently iron deficiency is known to impair mitochondrial function. Since the proximal tubular epithelial cells (PTECs) of the kidney are the cells with the greatest number of mitochondria in the body, we investigated whether iron deficiency impairs the mitochondrial capacity of the PTECs. Method Human cultured PTECs were analyzed in ‘control group’, ‘iron-deficient group ‘(co-cultured with deferiprone (DFP), an iron chelator), and ‘rescue group’ (co-cultured with DFP and FeCl3 which saturates the chelating ability of DFP), each with n ≥ 4 (MRC activities n = 4-5, others n ≥ 5). All analyses were performed after 24 hours of incubation. Values are shown as averages ± SEM. Results A Seahorse Extracellular Flux Analyzer showed that the basal oxygen consumption rates (OCRs) of control, iron-deficiency and rescue groups were 30.5 ± 1.2 pmol/min, 11.5 ± 0.7 pmol/min, and 31.1 ± 1.2 pmol/min, respectively, which revealed that basal OCRs of PTECs significantly decreased in the iron-deficient group. In addition, the analyzer also revealed that the activities of MRC for complexes I, II, and III, which have iron-sulfur clusters as their active centers, were significantly decreased in citrate synthase ratio to 77.6 ± 6.2%, 75.1 ± 6.4%, and 72.8 ± 9.3% of the control group, respectively, while complex IV was not significantly different at 84.9% of the control group. These reductions in MRC activities were not observed in the rescue group. Western blotting results also revealed that complex I, II, and III subunit proteins, NDUF9, SDHA, and UQCR2, were significantly reduced in the iron-deficient group (reduced to 38 ± 5.8%, 87 ± 8.8%, and 55 ± 5.7% of the control group, respectively). On the other hand, lactate concentrations in the culture medium of control group, iron-deficient group and rescue group were 1.73 ± 0.13 mmol, 3.01 ± 0.15 mmol and 1.61 ± 0.12 mmol, which revealed that glycolytic system was increased in the iron-deficient group, presumably to compensate for decreased oxidative phosphorylation. In response to intracellular iron deficiency, the iron regulatory protein 2 (IRP2) was shown in Western blotting to be unchanged in the rescue group (123 ± 4.0% of the control group), but increased in the iron-deficient group (170 ± 20% of the control group). The qRT-PCR analyses showed that mRNA expression of iron-sulfur cluster assembly enzyme (ISCU) was significantly decreased in the iron-deficiency group compared with the control group (41.8%), but not in the rescue group (95.1%), which is presumed that IRP2 suppressed ISCU expression, as has been proved previously. These results should indicate that iron deficiency suppressed iron utilization in the mitochondria of PTECs. The number of viable PTECs in the iron-deficient group after 24 hours was 1.99 ± 0.09 × 10^5 cells/well, which was significantly lower than that of the control (3.15 ± 0.15 × 10^5 cells/well) and rescue (2.68 ± 0.18 × 10^5 cells/well) groups. On the other hand, the number of dead PTECs was 0.042 ± 0.019 × 10^5 cells in the iron-deficient group, which was not significantly different from the control (0.023 ± 0.005 × 10^5 cells) and the rescue (0.020 ± 0.011 × 10^5 cells) groups. These data suggest that cell growth should be suppressed by iron deficiency. Conclusion Mitochondrial oxidative phosphorylation through the MRC was impaired by iron deficiency in PTECs. This impairment of mitochondrial capacity in PTECs may lead to PTECs dysfunction, potentially inducing renal damage such as cell death and interstitial injury. Further analysis of the effects of this mitochondrial dysfunction on ATP production capacity and reactive oxygen species production is needed.

Synthetic aporphine alkaloids are potential therapeutics for Leigh syndrome

Mitochondrial diseases are mainly caused by dysfunction of mitochondrial respiratory chain complexes and have a variety of genetic variants or phenotypes. There are only a few approved treatments, and fundamental therapies are yet to be developed. Leigh syndrome (LS) is the most severe type of progressive encephalopathy. We previously reported that apomorphine, an anti- “off” agent for Parkinson’s disease, has cell-protective activity in patient-derived skin fibroblasts in addition to strong dopamine agonist effect. We obtained 26 apomorphine analogs, synthesized 20 apomorphine derivatives, and determined their anti-cell death effect, dopamine agonist activity, and effects on the mitochondrial function. We found three novel apomorphine derivatives with an active hydroxy group at position 11 of the aporphine framework, with a high anti-cell death effect without emetic dopamine agonist activity. These synthetic aporphine alkaloids are potent therapeutics for mitochondrial diseases without emetic side effects and have the potential to overcome the low bioavailability of apomorphine. Moreover, they have high anti-ferroptotic activity and therefore have potential as a therapeutic agent for diseases related to ferroptosis.

Strobilurin X acts as an anticancer drug by inhibiting protein synthesis and suppressing mitochondrial respiratory chain activity

PurposeStrobilurins act as antifungal agents by inhibiting the mitochondrial respiratory chain. The cytotoxic activity of strobilurins, focusing on its anticancer activities, has been reported. However, the mechanisms involved in these activities remain unclear.MethodsThe cytotoxic effects of strobilurin X isolated from the mycelium of Mucidula. venosolamellata were examined in human cancer cell lines (A549 and HeLa) and normal fibroblasts (WI-38).ResultsStrobilurin X significantly decreased the viability of A549 and HeLa cells compared to that in the WI-38 cells after 48 h of exposure. The EC50 values for cytotoxicity in the A549, HeLa, and WI-38 cells were 3.4, 5.4, and 16.8 μg/mL, respectively. Strobilurin X inhibited the mitochondrial respiratory chain and enhanced the release of lactate in the A549 cells. The IC50 value of strobilurin X against the mitochondrial respiratory chain complex III activity was 139.8 ng/mL. The cytotoxicity induced by strobilurin X was not completely rescued after adding uridine, methyl pyruvate, or N-acetyl cysteine. Furthermore, pharmacological approaches demonstrated that strobilurin X failed to modulate the mitogen-activated protein kinase family and phosphoinositide 3-kinase-Akt pathways; alternatively, it suppressed protein synthesis independent of uridine.ConclusionStrobilurin X induced cytotoxicity by blocking the mitochondrial respiratory chain and suppressing protein synthesis. These findings may aid in the development of novel anticancer drugs using strobilurins.

Targeting the mitochondrial protein YME1L to inhibit osteosarcoma cell growth in vitro and in vivo

Exploring novel diagnostic and therapeutic biomarkers is extremely important for osteosarcoma. YME1 Like 1 ATPase (YME1L), locating in the mitochondrial inner membrane, is key in regulating mitochondrial plasticity and metabolic activity. Its expression and potential functions in osteosarcoma are studied in the present study. We show that YME1L mRNA and protein expression is significantly elevated in osteosarcoma tissues derived from different human patients. Moreover, its expression is upregulated in various primary and immortalized osteosarcoma cells. The Cancer Genome Atlas database results revealed that YME1L overexpression was correlated with poor overall survival and poor disease-specific survival in sarcoma patients. In primary and immortalized osteosarcoma cells, silencing of YME1L through lentiviral shRNA robustly inhibited cell viability, proliferation, and migration. Moreover, cell cycle arrest and apoptosis were detected in YME1L-silenced osteosarcoma cells. YME1L silencing impaired mitochondrial functions in osteosarcoma cells, causing mitochondrial depolarization, oxidative injury, lipid peroxidation and DNA damage as well as mitochondrial respiratory chain complex I activity inhibition and ATP depletion. Contrarily, forced YME1L overexpression exerted pro-cancerous activity and strengthened primary osteosarcoma cell proliferation and migration. YME1L is important for Akt-S6K activation in osteosarcoma cells. Phosphorylation of Akt and S6K was inhibited after YME1L silencing in primary osteosarcoma cells, but was strengthened with YME1L overexpression. Restoring Akt-mTOR activation by S473D constitutively active Akt1 mitigated YME1L shRNA-induced anti-osteosarcoma cell activity. Lastly, intratumoral injection of YME1L shRNA adeno-associated virus inhibited subcutaneous osteosarcoma xenograft growth in nude mice. YME1L depletion, mitochondrial dysfunction, oxidative injury, Akt-S6K inactivation, and apoptosis were detected in YME1L shRNA-treated osteosarcoma xenografts. Together, overexpressed YME1L promotes osteosarcoma cell growth, possibly by maintaining mitochondrial function and Akt-mTOR activation.

SIRT1 restores mitochondrial structure and function in rats by activating SIRT3 after cerebral ischemia/reperfusion injury

Mitochondrial dysfunction contributes to cerebral ischemia–reperfusion (CI/R) injury, which can be ameliorated by Sirtuin-3 (SIRT3). Under stress conditions, the SIRT3-promoted mitochondrial functional recovery depends on both its activity and expression. However, the approach to enhance SIRT3 activity after CI/R injury remains unelucidated. In this study, Sprague–Dawley (SD) rats were intracranially injected with either adeno-associated viral Sirtuin-1 (AAV-SIRT1) or AAV-sh_SIRT1 before undergoing transient middle cerebral artery occlusion (tMCAO). Primary cortical neurons were cultured and transfected with lentiviral SIRT1 (LV-SIRT1) and LV-sh_SIRT1 respectively before oxygen–glucose deprivation/reoxygenation (OGD/R). Afterwards, rats and neurons were respectively treated with a selective SIRT3 inhibitor, 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP). The expression, function, and related mechanism of SIRT1 were investigated by Western Blot, flow cytometry, immunofluorescence staining, etc. After CI/R injury, SIRT1 expression decreased in vivo and in vitro. The simulation and immune-analyses reported strong interaction between SIRT1 and SIRT3 in the cerebral mitochondria before and after CI/R. SIRT1 overexpression enhanced SIRT3 activity by increasing the deacetylation of SIRT3, which ameliorated CI/R-induced cerebral infarction, neuronal apoptosis, oxidative stress, neurological and motor dysfunction, and mitochondrial respiratory chain dysfunction, promoted mitochondrial biogenesis, and retained mitochondrial integrity and mitochondrial morphology. Meanwhile, SIRT1 overexpression alleviated OGD/R-induced neuronal death and mitochondrial bioenergetic deficits. These effects were reversed by AAV-sh_SIRT1 and the neuroprotective effects of SIRT1 were partially offset by 3-TYP. These results suggest that SIRT1 restores the structure and function of mitochondria by activating SIRT3, offering neuroprotection against CI/R injury, which signifies a potential approach for the clinical management of cerebral ischemia.Graphical 1. SIRT1 is downregulated after cerebral ischemia/reperfusion injury.2. SIRT1 can increase the deacetylation of SIRT3 and enhance the activity of SIRT3 after cerebral ischemia/reperfusion injury.3. SIRT1 enhances the mitochondrial structure repair and functional recovery by activating SIRT3 after cerebral ischemia/reperfusion injury in rats, thereby promoting neurological function.

A Novel <i>NDUFV2</i> Variant in an Asymptomatic Adolescent Girl with Progressive Cavitating Leukoencephalopathy

<b><i>Introduction:</i></b> Pathogenic variants in several genes encoding components of the mitochondrial respiratory chain have been linked to various clinical phenotypes such as progressive cavitating leukoencephalopathy (PCL). The association between PCL, previously linked to numerous gene mutations in the literature, and the <i>NDUFV2</i> gene mutations has emerged as a recent and noteworthy discovery. PCL is generally diagnosed in symptomatic patients during the early years of life, mostly in infancy. <b><i>Case Presentation:</i></b> In a previously healthy 12-year-old Turkish girl, a computed tomography scan taken for minor head trauma incidentally revealed suspicious hypodense areas in the periventricular white matter. Subsequently, a magnetic resonance imaging evaluation was performed. There was no history of motor regression, irritability, or seizures up to the age of 12. The case exhibited normal neurological and cranial nerve examinations. Magnetic resonance imaging detected bilateral periventricular T2/FLAIR hyperintensities with cystic areas suggestive of PCL. Whole-exome sequencing revealed the presence of a homozygous p.R222C missense variant in the <i>NDUFV2</i> gene. Over a 6-year follow-up period, the patient remained asymptomatic, and there were no discernible changes in the magnetic resonance imaging findings. <b><i>Conclusion:</i></b> This case underscores the association between a potentially causal variant at the <i>NDUFV2</i> locus and PCL. It is worth noting that this novel variation in PCL can not only manifest with symptoms in the infantile period but also remain asymptomatic into adolescence.

Acupuncture modulates the AMPK/PGC-1 signaling pathway to facilitate mitochondrial biogenesis and neural recovery in ischemic stroke rats

AimsThe main objective of this study was to investigate the role and mechanism of acupuncture on anti-nerve injury in the acute phase by regulating mitochondrial energy metabolism via monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) axis in rat ischemic stroke.Main methodsMiddle cerebral artery occlusion (MCAO) was established by middle cerebral artery occlusion/reperfusion. One-week of acupuncture was performed during the acute phase of ischemic stroke. The neurological function and brain tissue integrity were evaluated. Mitochondrial function (intracellular ATP level and the activity of mitochondrial respiratory chain complex I) and the level of NADH oxidase (NOX) were detected by enzymatic chemistry. Next, the potential molecular mechanisms were explored by western blotting, fluorescence quantitative PCR and immunohistochemistry method.Key findings(1) Acupuncture treatment for MCAO/R rats showed a significant improvement in the infarcted tissue accompanied by functional recovery in Zea-Longa score and balance beam score outcomes, motor function performances. (2) Acupuncture increased the levels of ATP and mitochondrial respiratory chain complex I, decreased the NOX levels in cerebral ischemia established by suture-occluded method. (3) Acupuncture reduced the necrosis dissolution of neuronal cells and meningeal edema, while promoting angiogenesis. (4) Quantitative immunohistochemical staining results showed acupuncture can increase the expression of AMPK, p-AMPK and the mitochondrial transcription factor PGC-1α, NRF2, TFAM and uncoupling protein 2 (UCP2). Meanwhile, acupuncture treatment up-regulated the expression of the corresponding protein. (5) Subsequently, acupuncture enhanced AMPK phosphorylation as well as the expression of PGC-1α, NRF2, TFAM and UCP2, implicated in mitochondrial synthesis and cellular apoptosis. (6) Finally, injections of AMPK antagonists and activators confirmed AMPK as a therapeutic target for the anti-nerve damage effects of acupuncture.SignificanceAcupuncture intervention relieved ischemic stroke progression in MCAO rats by promoting energy metabolism and mitochondrial biogenesis in the brain and alleviating neuronal apoptosis, which was mediated by eliciting AMPK/PGC-1α axis, among them AMPK is a therapeutic target.

Irisin inhibits microglial senescence via TFAM-mediated mitochondrial metabolism in a mouse model of tauopathy

BackgroundThe accumulation of senescent microglia has been highlighted as a critical contributor to the progression of tauopathies. Irisin, a muscle-derived hormone produced by the proteolytic cleavage of Fibronectin-domain III containing 5 (FNDC5), mediates the pleiotropic effects of exercise on the physical body. Herein, we investigate the potential role of irisin in microglial senescence in tauopathies.MethodsTo model tauopathies both in vivo and in vitro, we utilized P301S tau transgenic mice and tau K18 fibril-treated microglia BV2 cells, respectively. We first examined the expression of the irisin expression and senescence phenotypes of microglia in tauopathies. Subsequently, we investigated the impact of irisin on microglial senescence and its underlying molecular mechanisms.ResultWe observed a reduction in irisin levels and an onset of premature microglial senescence both in vivo and in vitro. Irisin administration was found to counteract microglial senescence and ameliorate cognitive decline in P301S mice. Mechanistically, irisin effectively inhibited microglial senescence by stimulating the expression of mitochondrial transcription factor A (TFAM), a master regulator of mitochondrial respiratory chain biogenesis, thereby enhancing mitochondrial oxidative phosphorylation (OXPHOS). Silencing TFAM eliminated the inhibitory effect of irisin on microglial senescence as well as the restorative effect of irisin on mitochondrial OXPHOS. Furthermore, the SIRT1/PGC1α signaling pathway appeared to be implicated in irisin-mediated upregulation of TFAM.ConclusionTaken together, our study revealed that irisin mitigated microglial senescence via TFAM-driven mitochondrial biogenesis, suggesting a promising new avenue for therapeutic strategies targeting tauopathies.

Cuproptosis in lung cancer: therapeutic options and prognostic models.

Lung cancer (LC) is a serious threat to mankind. The survival of LC patients is still poor despite the enormous efforts that have been made to develop novel treatments. A copper-dependent cell death termed cuproptosis is distinct from known programmed cell death (PCD). Cuproptosis is induced by the disruption of the binding of copper to lipoylated tricarboxylic acid (TCA) cycle proteins of mitochondrial respiratory chains. Potential approaches for treating LC are inducing cell cuproptosis and targeting cell copper death mechanisms. Thus, in this review, we summarize the systemic and cellular metabolic processes of copper. We highlight the possible therapeutic options of employing copper ionophores and chelators for inducing cuproptosis. Moreover, we summarize the prognostic models based on cuproptosis-related genes (CRGs) to identify promising biomarkers for tumor diagnosis and therapy. This review aims to provide a comprehensive summary of CRGs-based prognostic models and promising therapeutic options for cuproptosis induction in LC.

Time-dependent proteomics and drug response in expanding cancer cells

Cancer cell line is commonly used for discovery and development of anti-cancer drugs. It is generally considered that drug response remains constant for a certain cell line due to the identity of genetics thus protein patterns. Here, we demonstrated that cancer cells continued dividing even after reaching confluence, in that the proteomics was changed continuously and dramatically with strong relevance to cell division, cell adhesion and cell metabolism, indicating time-dependent intrinsically reprogramming of cells during expansion. Of note, the inhibition effect of most anti-cancer drugs was strikingly attenuated in culture cells along with cell expansion, with the strongest change at the third day when cells were still expanding. Profiling of an FDA-approved drug library revealed that attenuation of response with cell expansion is common for most drugs, an exception was TAK165 that was a selective inhibitor of mitochondrial respiratory chain complex I. Finally, we screened a panel of natural products and identified four pentacyclic triterpenes as selective inhibitors of cancer cells under prolonged growth. Taken together, our findings underscore that caution should be taken in evaluation of anti-cancer drugs using culture cells, and provide agents selectively targeting overgrowth cancer cells.

Unveiling the molecular basis of paracetamol-induced hepatotoxicity: Interaction of N-acetyl-p-benzoquinone imine with mitochondrial succinate dehydrogenase

Background and aimN-acetyl-p-benzoquinoneimine (NAPQI), a toxic byproduct of paracetamol (Acetaminophen, APAP), can accumulate and cause liver damage by depleting glutathione and forming protein adducts in the mitochondria. These adducts disrupt the respiratory chain, increasing superoxide production and reducing ATP. The goal of this study was to provide computational proof that succinate dehydrogenase (SDH), a subunit of complex II in the mitochondrial respiratory chain, is a favorable binding partner for NAPQI in this regard. MethodMolecular docking, molecular dynamics simulation, protein-protein interaction networks (PPI), and KEGG metabolic pathway analysis were employed to identify binding characteristics, interaction partners, and their associations with metabolic pathways. A lipid membrane was added to the experimental apparatus to mimic the natural cellular environment of SDH. This modification made it possible to develop a context for investigating the role and interactions of SDH within a cellular ecosystem that was more realistic and biologically relevant. ResultThe molecular binding affinity score for APAP and NAPQI with SDH was predicted −6.5 and −6.7 kcal/mol, respectively. Furthermore, RMSD, RMSF, and Rog from the molecular dynamics simulations study revealed that NAPQI has slightly higher stability and compactness compared to APAP at 100 ns timeframe with mitochondrial SDH. ConclusionThis study serves to predict the mechanistic process of paracetamol toxicity by using different computational approaches. In addition, this study will provide information about the drug target against APAP hepatotoxicity.

Anticancer activity of 8-hydroxyquinoline-triphenylphosphine rhodium(III) complexes targeting mitophagy pathways

Metallodrugs exhibiting distinct mechanisms of action compared with cisplatin hold promise for overcoming cisplatin resistance and improving the efficacy of anticancer drugs. In this study, a new series of rhodium (Rh)(III) complexes containing tris(triphenylphosphine)rhodium(I) chloride [(TPP)3RhCl] (TPP = triphenylphosphine, TPP=O = triphenylphosphine oxide) and 8-hydroxyquinoline derivatives (H-XR1–H-XR4), namely [Rh(XR1)2(TPP)Cl]·(TPP=O) (Yulin Normal University-1a [YNU-1a]), [Rh(XR2)2(TPP)Cl] (YNU-1b), [Rh(XR3)2(TPP)Cl] (YNU-1c), and [Rh(XR4)2(TPP)Cl] (YNU-1d), was synthesized and characterized via X-ray diffraction, mass spectrometry and IR. The cytotoxicity of the compounds YNU-1a–YNU-1d in Hep-G2 and HCC1806 human cancer cell lines and normal HL-7702 cell line was evaluated. YNU-1c exhibited cytotoxicity and selectivity in HCC1806 cells (IC50 = 0.13 ± 0.06 μM, selectivity factor (SF) = 384.6). The compounds YNU-1b and YNU-1c, which were selected for mechanistic studies, induced the activation of apoptotic pathways and mitophagy. In addition, these compounds released cytochrome c, cleaved caspase-3/pro-caspase-3 and downregulated the levels of mitochondrial respiratory chain complexes I/IV (M1 and M4) and ATP. The compound YNU-1c, which was selected for in vivo experiments, exhibited tumor growth inhibition (58.9 %). Importantly, hematoxylin and eosin staining and TUNEL revealed that HCC1806 tumor tissues exhibited significant apoptotic characteristics. YNU-1a–YNU-1d compounds are promising drug candidates that can be used to overcome cisplatin resistance.

Effect of Rotenone on the Neurodegeneration among Different Models.

Rotenone is a naturally occurring plant product used as an insecticide, pesticide and piscicide. It is lipophilic in nature and can cross the blood-brain barrier and induce the degeneration of neurons. It inhibits the mitochondrial respiratory chain complex I and stops the transfer of electrons. It induces ROS generation, which impairs mitochondrial activity. Rotenone is a toxic agent which causes the death of neurons. The present review describes the effect of rotenone on neurodegeneration with an emphasis on behavioral, pathological and neuropathological components carried out on various experimental models such as cell lines, Drosophila melanogaster, mice and rats.

Hypoxia induces pyroptosis and inflammation in the liver of fat greenling (Hexagrammos otakii)

In fisheries, hypoxia stress is one of the most common environmental stresses that often cause significant harm and losses to the aquaculture industry. The liver is the most important metabolic organ of the body, which is involved in energy metabolism, synthesizes various physiologically active substances, and is an important target organ for hypoxia in fish. This study investigated how acute hypoxia stress induces liver injury and mortality of Hexagrammos otakii. During the hypoxia treatment, reactive oxygen species (ROS), a metabolic intermediary made by the mitochondrial respiratory chain, are highly accumulated, the level of lipid peroxidation increased significantly in the liver tissue. The vacuolation of liver histiocyte is enhanced due to hypoxia. The downstream gene hypoxia-inducible factor (HIF)-1 can react to the elevated ROS in liver tissue. HIF-1α expression levels greatly increase when hypoxia is applied, which prompts the activation of the nlrp3/caspase-1/il-1β and caspase-3/gsdme pathway and encourages the inflammation and pyroptosis of the liver. After reoxygenation, nlrp3/caspase-1/il-1β pathway are reactivated and cause liver damage in H. otakii. In conclusion, it has been shown that hypoxia-stress modulates the expression of HIF-1 through an increase in ROS production, which then encourages the activation of the nlrp3/caspase-1/il-1β and caspase-3/gsdme pathway to cause liver injury. This research sheds fresh light on the mechanism of hypoxia-induced pyroptosis and demonstrates the usefulness of the ROS-HIF-1 signaling pathway as a possible therapeutic target to halt the progression of hypoxia-induced illnesses.

Mitochondrial citrate transporters Ctp1-Yhm2 and respiratory chain: A coordinated functional connection in Saccharomyces cerevisiae metabolism

The mitochondrial inner membrane contains some hydrophobic proteins that mediate the exchange of metabolites between the mitochondrial matrix and the cytosol. Ctp1 and Yhm2 are two carrier proteins in the yeast Saccharomyces cerevisiae responsible for the transport of citrate, a tricarboxylate involved in several metabolic pathways.Since these proteins also contribute to respiratory metabolism, in this study we investigated for the first time whether changes in citrate transport can affect the structural organization and functional properties of respiratory complexes.Through experiments in yeast mutant cells in which the gene encoding Ctp1 or Yhm2 was deleted, we found that in the absence of either mitochondrial citrate transporter, mitochondrial respiration was impaired. Structural analysis of the respiratory complexes III and IV revealed different expression levels of the catalytic and supernumerary subunits in the Δctp1 and Δyhm2 strains. In addition, Δyhm2 mitochondria appeared to be more sensitive than Δctp1 to the oxidative damage.Our results provide the first evidence for a coordinated modulation of mitochondrial citrate transport and respiratory chain activity in S. cerevisiae metabolism.

N-Butylphthalide Potentiates the Effect of Fluconazole Against Drug-Resistant Candida glabrata and Candida tropicalis. Evidence for Its Mechanism of Action.

To define the antifungal activity of n-butylphthalide alone or in combination with fluconazole in Candida glabrata and Candida tropicalis. The antifungal activity of n-butylphthalide alone and in combination with fluconazole was investigated by the classical broth microdilution method and the time-killing curve method. The QRT-PCR method was used to determine gene expressions changes of mitochondrial respiratory chain enzymes, drug efflux pumps and drug target enzymes in Candida glabrata and Candida tropicalis after n-butylphthalide treatment. The MIC values of n-butylphthalide against Candida glabrata and Candida tropicalis ranged from 16 to 64 μg·mL-1. The FICI value of the combination of n-butylphthalide and fluconazole against drug-resistant Candida glabrata and Candida tropicalis ranged from 0.5001 to 0.5315 with partial synergism. Time-killing curves showed that 256 μg·mL-1 n-butylphthalide significantly inhibited the growth of drug-resistant colonies of Candida glabrata and Candida tropicalis, and 128 μg·mL-1 n-butylphthalide combined with 1 μg·mL-1 fluconazole had an additive effect. N-butylphthalide could alter the expression of mitochondrial respiratory chain enzymes COX1, COX2, COX3, and CYTB genes in Candida glabrata and Candida tropicalis (P< 0.05) and downregulate the expression of the drug efflux pump genes CDR1 and CDR2 in drug-resistant Candida glabrata to 3.36% and 3.65%, respectively (P<0.001), but did not affect the drug target enzyme ERG11 in drug-resistant Candida tropicalis. N-butylphthalide had antifungal activity against Candida glabrata and Candida tropicalis. N-butylphthalide improved the activity of fluconazole against drug-resistant Candida glabrata by affecting the expression of mitochondrial respiratory chain enzyme genes and reversing the high expression of drug efflux pump genes CDR1 and CDR2.

Increased Farnesoid X Receptor agonism in frontal cortex is associated with neuronal loss in a pig model of pediatric non-alcoholic fatty liver disease

Clinical studies suggest a link between non-alcoholic fatty liver disease (NAFLD) and neurodegeneration, but the mechanisms connecting both pathologies remain unknown. Rodent models of liver failure have shown neurological decline to be associated with increased bile acid (BA) levels and BA-activated farnesoid X receptor (FXR) signaling in the brain, which may disrupt brain’s cholesterol metabolism and promote neuronal death. We have previously established a pediatric animal model of NAFLD by feeding juvenile Iberian pigs a diet high in fat and fructose (HFF) for 10 weeks. The aim of this study was to determine whether BAs and FXR gene expression were increased in the frontal cortex (FC) of NAFLD pigs, and whether these changes were associated with neuronal loss. Eighteen 15-day-old Iberian pigs were assigned to receive for 10 weeks either a control (CON) or a HFF diet. FC was collected for immunohistochemistry, metabolomics, and transcriptomics analyses. Functional enrichment analyses were performed on differentially expressed genes to identify Gene Ontology (GO) terms using the Database for Annotation, Visualization, and Integrated Discovery. All HFF-fed pigs developed NAFLD. Immunostaining of mature neurons with NeuN was lower in FC of HFF compared with CON (P ≤ 0.05), whereas total BA levels increased (P ≤ 0.05) in FC of HFF-fed pigs. Brain levels of cholic and conjugated deoxycholic acids, which are FXR agonists, increased ( P ≤ 0.05) in HFF compared with CON. Conversely, tauroursodeoxycholic acid, which has strong FXR-antagonistic effect and has been shown to exert neuroprotective functions, was decreased (P ≤ 0.001) in HFF and was positively correlated with NeuN staining intensity (R2 = 0.623; P ≤ 0.001). Expression of FC genes encoding FXR, BA synthetic enzymes sterol 24- and 27-hydroxylases, and BA transporters Na+-taurocholate cotransporting polypeptide, organic anion transporting polypeptide, and organic solute transporters alpha and beta did not differ between groups. GO terms associated with Wnt/β-catenin pathway, which promotes neuronal survival and neurogenesis, were downregulated in HFF-fed pigs ( P ≤ 0.05), whereas mitochondrial respiratory chain complex and mitochondrion increased in HFF compared with CON ( P ≤ 0.01). In conclusion, increased BA levels and FXR agonism in frontal cortex of NAFLD pigs was associated with dysregulated Wnt/β-catenin signaling pathway and neuronal loss. California State University Agriculture Research Institute (grants 58873 and 58913), California Polytechnic State University internal funding programs Baker/Koob, RSCA, Frost, BiOWiSH Technologies, Hilmar Ingredients, and Acorn Seekers. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Intrauterine Hyperglycemia Induces SIRT3-mediated Mitochondrial Dysfunction: The Fetal Origin Pathogenesis of Precocious Osteoarthritis

Diabetes and other metabolic and inflammatory comorbidities are highly associated with osteoarthritis. However, whether early-life hyperglycemia exposure affects susceptibility to long-term osteoarthritis is still unknown. The purpose of this study was to explore the fetal origins of osteoarthritis and provide insights into early-life safeguarding for individual health. This study utilized STZ to induce intrauterine hyperglycemia and performed DMM surgery on the knee joints of the offspring mice to induce accelerated osteoarthritis. Cartilage degeneration-related markers, as well as the expression levels of mitochondrial respiratory chain complexes and mitophagy genes in the adult offspring mice, were investigated. In vitro, mitochondrial function and mitophagy of chondrocyte C28/I2 cells stimulated under high glucose conditions were also evaluated. The methylation levels of the sirt3 gene promoter region in the articular cartilage of intrauterine hyperglycemia-exposed offspring mice were further analyzed. In this study, we found that the intrauterine hyperglycemic environment could lead to an increase in individual susceptibility to osteoarthritis in late adulthood, mainly due to persistently low levels of Sirt3 expression. Downregulation of Sirt3 causes impaired mitophagy in chondrocytes and abnormal mitochondrial respiratory function due to a failure to clear aged and damaged mitochondria in a timely manner. Overexpressing Sirt3 at the cellular level or using Sirt3 agonists like Honokiol in mouse models can partially rescue mitophagy disorders caused by the hyperglycemic environment and thus alleviate the progression of osteoarthritis. Our study revealed a significantly increased susceptibility to OA in the GDM offspring, which is partly attributed to exposure to adverse factors in utero and ultimately to the onset of disease via epigenetic modulation. All data are available from the corresponding authors upon reasonable request.