Impaired Mitochondrial Function Research Articles

Dysregulated Mitochondrial Calcium Causes Spiral Artery Remodeling Failure in Preeclampsia.

Calcium deficiency in women is strongly linked to an increased risk of developing preeclampsia. Mitochondrial calcium ([Ca2+]m) homeostasis is essential to regulate vascular smooth muscle cell (VSMC) function. However, the role of [Ca2+]m in preeclampsia development remains largely unknown. To investigate this, human spiral arteries obtained from normotensive and preeclamptic women were collected for vascular function, RNA sequencing, and VSMC studies. N(ω)-nitro-L-arginine methyl ester-induced preeclampsia animal experiments were established to investigate the effects of intervening in [Ca2+]m to improve the outcome for preeclamptic mothers or their infants. Our initial findings revealed compromised vessel function in spiral arteries derived from patients with preeclampsia, as evidenced by diminished vasoconstriction and vasodilation responses to angiotensin II and sodium nitroprusside, respectively. Moreover, the spiral artery VSMCs from patients with preeclampsia exhibited phenotypic transformation and proliferation associated with the disrupted regulatory mechanisms of [Ca2+]m uptake. Subsequent in vitro experiments employing gain- and loss-of-function approaches demonstrated that the mitochondrial Na+/Ca2+ exchanger played a role in promoting phenotypic switching and impaired mitochondrial functions in VSMCs. Furthermore, mtNCLX (mitochondrial Na+/Ca2+ exchanger) inhibitor CGP37157 significantly improved VSMC phenotypic changes and restored mitochondrial function in both patients with preeclampsia-derived VSMCs and the preeclampsia rat model. This study provides comprehensive evidence supporting the disrupted regulatory mechanisms of [Ca2+]m uptake in VSMCs of spiral arteries of patients with preeclampsia and further elucidates its correlation with VSMC phenotypic switching and defective spiral artery remodeling. The findings suggest that targeting mtNCLX holds promise as a novel therapeutic approach for managing preeclampsia.

Navigating the Neurobiology of Parkinson’s: The Impact and Potential of α-Synuclein

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease worldwide; therefore, since its initial description, significant progress has been made, yet a mystery remains regarding its pathogenesis and elusive root cause. The widespread distribution of pathological α-synuclein (αSyn) aggregates throughout the body raises inquiries regarding the etiology, which has prompted several hypotheses, with the most prominent one being αSyn-associated proteinopathy. The identification of αSyn protein within Lewy bodies, coupled with genetic evidence linking αSyn locus duplication, triplication, as well as point mutations to familial Parkinson’s disease, has underscored the significance of αSyn in initiating and propagating Lewy body pathology throughout the brain. In monogenic and sporadic PD, the presence of early inflammation and synaptic dysfunction leads to αSyn aggregation and neuronal death through mitochondrial, lysosomal, and endosomal functional impairment. However, much remains to be understood about αSyn pathogenesis, which is heavily grounded in biomarkers and treatment strategies. In this review, we provide emerging new evidence on the current knowledge about αSyn’s pathophysiological impact on PD, and its presumable role as a specific disease biomarker or main target of disease-modifying therapies, highlighting that this understanding today offers the best potential of disease-modifying therapy in the near future.

Abstract PR-13: Disruption of sulfatide metabolism by targeting UGT8 is an actionable metabolic vulnerability for pancreatic cancer early interception

Abstract The existence of asymptomatic precursor lesions that are known to predate invasive pancreatic ductal adenocarcinoma (PDAC) by years provides a compelling rationale for cancer interception efforts. One such precursor is intraductal papillary mucinous neoplasm (IPMN). Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) imaging of metabolites in tissue sections from resected patient IPMN cases (N=23) and from a KrasG12D/GnasR201C mouse model of IPMN, we have made a discovery of long chain hydroxylated sulfatide species as being selectively enriched in IPMN. Spatial transcriptomics analysis of serial sections from the same IPMN tissues confirmed cognate transcripts, including ceramide galactosyltransferase (CGT, also known as UGT8) and galactose-3-O-sulfotransferase (CST, also known as Gal3St1) enzymes that, respectively, catalyze the addition of galactose from UDP-galactose to ceramide and the O-sulfation of the galactose residue on galactosylceramide (GalCer), to also be highly enriched in IPMN. Functional studies using CRISPR/cas9 UGT8 knockout Kras;Gnas IPMN cells demonstrated that loss of UGT8, the key enzyme that produces the sulfatide precursor GalCer, results in attenuation of sulfatide biosynthesis and impaired mitochondrial function, as evidenced by reduced mitochondrial respiration and ATP production. These changes were met with concomitant decreases in proliferation and invasiveness, and increased susceptibility to intrinsic apoptosis. Targeting of sulfatide metabolism using a selective small molecule inhibitor of UGT8 suppressed sulfatide biosynthesis, induced ceramide-mediated compensatory mitophagy, and subsequent apoptosis in Kras;Gnas IPMN cells. In vivo, UGT8 inhibition suppressed tumor growth in an IPMN allograft model. In conclusion, our work identifies enhanced sulfatide metabolism as an early metabolic alteration in cystic pre-cancerous lesions of the pancreas that persists through invasive neoplasia and represents an actionable vulnerability for PDAC early interception. Citation Format: Riccardo Ballarò, Yihui Chen, Fredrik I Thege, Rongzhang Dou, Jimin Min, Michele Yip-Schneider, Jianjun Zhang, Ranran Wu, Ehsan Irajizad, Yuki Makino, Kimal I Rajapakshe, Mark W Hurd, Ricardo A León-Letelier, Edwin Ostrin, Jody Vykoukal, Jennifer B Dennison, Kim-Anh Do, Samir Hanash, Robert A Wolff, Paola A Guerrero, Michael P Kim, C Max Schmidt, Anirban Maitra, Johannes F Fahrmann. Disruption of sulfatide metabolism by targeting UGT8 is an actionable metabolic vulnerability for pancreatic cancer early interception [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-13.

Abstract B004: Targeting Metabolic Vulnerabilities in Pancreatic Cancer: The Synergistic Anti- Tumor Effects of a Ketogenic Diet and IDH1 Inhibition

Abstract Background: A ketogenic diet, characterized by high fat (90% kCal) and low carbohydrates (5% kCal), induces ketosis. Previous research suggests that a ketogenic diet shifts cancer cell metabolism from glycolysis to the tricarboxylic acid (TCA) cycle in the mitochondria. While the overall impact on cancer growth remains uncertain, most studies suggest an anti-cancer effect. We hypothesize that understanding the molecular and biochemical adaptations of pancreatic cancer cells to a ketogenic diet will reveal metabolic vulnerabilities and lead to rational therapeutic strategies that complement the diet. Methods: Mice were fed a ketogenic diet, with control mice on a normal diet. Pancreatic cancer xenografts were monitored for growth and subjected to biochemical analyses. Tumor metabolites were measured using LC/GC-MS, and oxidative stress was assessed by NADP+/NADPH, NAD+/NADH levels, and lipid peroxidation assays. Enzyme expression was determined by Western blot. In vitro, mitochondrial function was analyzed using the Seahorse FX Analyzer, and cell growth was measured by PicoGreen DNA quantitation. Results: A ketogenic diet slowed pancreatic cancer growth in multiple in vivo models, including MIA-PaCa2, KPC, and patient-derived xenografts. TCA metabolites increased in xenografts exposed to the ketogenic diet, with a significant upregulation of TCA cycle-associated enzymes. Specifically, the expression of BDH1 (a ketolytic enzyme), IDH1 (supports antioxidant defense and mitochondrial function), and IDH2 (mitochondrial homolog of IDH1) were elevated. Conversely, the glycolytic enzyme G3P was reduced. Additionally, a ketogenic diet induced oxidative stress in pancreatic cancer in vivo. Combining a ketogenic diet with an IDH1 inhibitor impaired antioxidant defense and mitochondrial function, resulting in significantly reduced tumor proliferation compared to either treatment alone. In vitro studies indicated that low glucose and fatty acids primarily drive the reduced proliferation of pancreatic cancer cells on a ketogenic diet, while exogenous ketone bodies are utilized for energy under glucose deprivation, generally promoting tumor growth. Conclusion: A ketogenic diet exerts a strong anti-tumor effect in multiple pancreatic cancer mouse models, likely due to low glucose and increased fatty acid load. The metabolic shift towards an oxidative phosphorylation (OXPHOS) phenotype makes pancreatic cancer cells particularly vulnerable to antioxidant and mitochondrial inhibitors. Citation Format: Omid Hajihassani, Mehrdad Zarei, Soubhi Tahan, Peter Gallagher, William Beegan, John Speers, James Choi, Aya Murray, Alexander Loftus, Helen Cheng, Anusha Mudigonda, Karen Ji, Jonathan Hue, Hallie Graor, Jordan Winter. Targeting Metabolic Vulnerabilities in Pancreatic Cancer: The Synergistic Anti- Tumor Effects of a Ketogenic Diet and IDH1 Inhibition [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B004.

Skeletal Muscle Involvement in Friedreich Ataxia

Friedreich Ataxia (FRDA) is an inherited neuromuscular disorder triggered by a deficit of the mitochondrial protein frataxin. At a cellular level, frataxin deficiency results in insufficient iron–sulfur cluster biosynthesis and impaired mitochondrial function and adenosine triphosphate production. The main clinical manifestation is a progressive balance and coordination disorder which depends on the involvement of peripheral and central sensory pathways as well as of the cerebellum. Besides the neurological involvement, FRDA affects also the striated muscles. The most prominent manifestation is a hypertrophic cardiomyopathy, which also represents the major determinant of premature mortality. Moreover, FRDA displays skeletal muscle involvement, which contributes to the weakness and marked fatigue evident throughout the course of the disease. Herein, we review skeletal muscle findings in FRDA generated by functional imaging, histology, as well as multiomics techniques in both disease models and in patients. Altogether, these findings corroborate a disease phenotype in skeletal muscle and support the notion of progressive mitochondrial damage as a driver of disease progression in FRDA. Furthermore, we highlight the relevance of skeletal muscle investigations in the development of biomarkers for early-phase trials and future therapeutic strategies in FRDA.

Elevated concentrations of amyloid-β oligomers and their proapoptotic effects on age-related cataract.

Recently, amyloid-β oligomers (AβOs) have been studied as the primary pathogenic substances in Alzheimer's disease (AD). Our previous study revealed that the Aβ expression level is closely related to ARC progression. Here, we demonstrated that the accumulation of AβOs in the lens epithelium of age-related cataract (ARC) patients increased during ARC progression and that this alteration was consistent with the changes in mitochondrial function, oxidative stress, and cellular apoptosis. Invitro, human lens epithelial cells (HLECs) treated with AβOs exhibited Ca2+ dyshomeostasis, impaired mitochondrial function, elevated oxidative stress levels, and increased apoptosis. Moreover, the proapoptotic effect of AβOs was alleviated after the uptake of mitochondrial Ca2+ was inhibited. These results establish that AβOs may promote HLEC apoptosis by inducing mitochondrial Ca2+ overload, thus preliminarily revealing the possible association between the accumulation of AβOs and other pathological processes in ARC.

Unraveling the Mfn2-Warburg effect nexus: a therapeutic strategy to combat pulmonary arterial hypertension arising from catch-up growth after IUGR

BackgroundThe interplay between intrauterine and early postnatal environments has been associated with an increased risk of cardiovascular diseases in adulthood, including pulmonary arterial hypertension (PAH). While emerging evidence highlights the crucial role of mitochondrial pathology in PAH, the specific mechanisms driving fetal-originated PAH remain elusive.Methods and resultsTo elucidate the role of mitochondrial dynamics in the pathogenesis of fetal-originated PAH, we established a rat model of postnatal catch-up growth following intrauterine growth restriction (IUGR) to induce pulmonary arterial hypertension (PAH). RNA-seq analysis of pulmonary artery samples from the rats revealed dysregulated mitochondrial metabolic genes and pathways associated with increased pulmonary arterial pressure and pulmonary arterial remodeling in the RC group (postnatal catch-up growth following IUGR). In vitro experiments using pulmonary arterial smooth muscle cells (PASMCs) from the RC group demonstrated elevated proliferation, migration, and impaired mitochondrial functions. Notably, reduced expression of Mitofusion 2 (Mfn2), a mitochondrial outer membrane protein involved in mitochondrial fusion, was observed in the RC group. Reconstitution of Mfn2 resulted in enhanced mitochondrial fusion and improved mitochondrial functions in PASMCs of RC group, effectively reversing the Warburg effect. Importantly, Mfn2 reconstitution alleviated the PAH phenotype in the RC group rats.ConclusionsImbalanced mitochondrial dynamics, characterized by reduced Mfn2 expression, plays a critical role in the development of fetal-originated PAH following postnatal catch-up growth after IUGR. Mfn2 emerges as a promising therapeutic strategy for managing IUGR-catch-up growth induced PAH.

Glutathione peroxidase 3 is essential for countering senescence in adipose remodelling by maintaining mitochondrial homeostasis

Adipose tissue senescence is a precursor to organismal aging and understanding adipose remodelling contributes to discovering novel anti-aging targets. Glutathione peroxidase 3 (GPx3), a critical endogenous antioxidant enzyme, is diminished in the subcutaneous adipose tissue (sWAT) with white adipose expansion. Based on the active role of the antioxidant system in counteracting aging, we investigated the involvement of GPx3 in adipose senescence. We determined that knockdown of GPx3 in adipose tissue by adeno-associated viruses impaired mitochondrial function in mice, increased susceptibility to obesity, and exacerbated adipose tissue senescence. Impairment of GPx3 may cause mitochondrial dysfunction through inner mitochondrial membrane disruption. Adipose reshaping management (cold stimulation and intermittent diet) counteracted the aging of tissues, with an increase in GPx3 expression. Overall metabolic improvement induced by cold stimulation was partially attenuated when GPx3 was depleted. GPx3 may be involved in adipose browning by interacting with UCP1, and GPx3 may be a limiting factor for intracellular reactive oxygen species (ROS) accumulation during stem cell browning. Collectively, these findings emphasise the importance of restoring the imbalanced redox state in adipose tissue to counteract aging and that GPx3 may be a potential target for maintaining mitochondrial homeostasis and longevity.

Exploring the neuroprotective potential of Nrf2-pathway activators against annonacin toxicity

Modulation of the Nrf2 pathway, a master regulator of the antioxidant response and cellular metabolism, has been suggested as a promising therapeutic strategy in tauopathies, a heterogeneous group of neurodegenerative disorders characterized by intracellular proteinaceous inclusions of abnormally phosphorylated tau. Here, we explored the neuroprotective potential of different Nrf2-pathway activators in human immortalized dopaminergic neurons against annonacin-induced toxicity, a mitochondrial inhibitor associated with a PSP-like syndrome and capable of mimicking tauopathy-like features. Interestingly, we observed heterogenous and compound-dependent neuroprotective effects among the different Nrf2-pathway activators. With the exception of Fyn inhibitors, all the selected Nrf2-pathway activators improved cell viability and the oxidative status, and reduced the annonacin-induced tau hyperphosphorylation and neurite degeneration, particularly the p62-activators. However, improvement of the impaired mitochondrial function was only observed by the Bach-1 inhibitor. Surprisingly, we found evidence that ezetimibe, an approved drug for hypercholesterolemia, prevents the transcriptional upregulation of 4R-tau triggered by annonacin insult. Overall, our results suggest that the neuroprotective effects of the Nrf2-pathway activators against annonacin toxicity may rely on the specific mechanism of action, intrinsic to each compound, and possibly on the concomitant modulation of additional signaling pathways. Further research will be needed to fully understand how synergistic modulation of metabolic adaptation and cell survival can be exploit to develop new therapeutical strategies for tauopathies and eventually other neurodegenerative diseases.

Overcoming cisplatin resistance in ovarian cancer: A novel approach via mitochondrial targeting peptide Pal-pHK-pKV

Cisplatin (DDP) resistance in advanced stages of ovarian cancer significantly reduces survival rates. Mitochondria may serve as a potential therapeutic target for ovarian cancer. Pal-pHK-pKV is a mitochondrial targeting peptide synthesized by supramolecular assembly. Our study aims to investigate whether Pal-pHK-pKV serves as a useful strategy to reverse DDP resistance in ovarian cancer. Subcutaneous tumor implantation of the DDP-resistant ovarian cancer cell line A2780CP was conducted in nude mice, and drugs were administered intraperitoneally to compare the inhibitory effects of Pal-pHK-pKV and DDP on A2780CP cells in vivo. Combination index values were calculated for various concentrations of DDP and Pal-pHK-pKV to determine the optimal combination concentration. Mitochondrial membrane potential, cytochrome C distribution and immunofluorescence were also measured. Our studies demonstrated that Pal-pHK-pKV treatment reduced the proliferation, invasion and metastasis of ovarian cancer cells and impaired mitochondrial function. Furthermore, the combination of Pal-pHK-pKV and DDP exhibited a synergistic effect. Mechanistically, Pal-pHK-pKV can impair mitochondrial function, reduce mitochondrial membrane potential and release ROS. On the other hand, Pal-pHK-pKV can affect ERK pathway activation and inhibit tumor development. In conclusion, the mitochondria-specific amphiphilic peptide Pal-pHK-pKV provides a novel approach for treating ovarian cancer and may potentially overcome DDP drug resistance.

MicroRNA 29a alleviates mitochondrial stress in diet-induced NAFLD by inhibiting the MAVS pathway

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder characterized by fat accumulation in the liver. This leads to aggravated hepatocyte inflammation due to impaired mitochondrial function, mitochondrial double-stranded RNA (mt-dsRNA) release, elevated oxidative stress, and reactive oxygen species (ROS) production.MicroRNA-29a (miR-29a) is used to reduce hepatic fibrosis in cases of cholestatic liver damage and lessen the severity of non-alcoholic steatohepatitis in animal studies by influencing mitochondrial protein balance. However, the effectiveness of miR-29a in diminishing mt-dsRNA-induced exacerbation of NAFLD remains poorly understood, particularly in the context of a Western diet (WD). Our results have found that mice with increased miR-29a levels and fed a WD showed notably decreased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, and low-density lipoprotein cholesterol levels. They also experienced less weight gain and lower final body and liver weights. In addition, overexpression of miR-29a reduced the severity of fibrosis, alleviated hepatic oxidative stress, misfolded protein aggregates, and the release of mt-dsRNA. Moreover, miR-29a attenuated the innate immune mitochondrial antiviral-signaling protein (MAVS) pathway response. In vitro, the research using HepG2 cells confirmed that miR-29a reduces MAVS expression and decreases the release of mt-dsRNA and superoxide initiated by palmitic acid (PA). Analysis of luciferase activity further established that the specific binding of miR-29a to the 3′UTR of MAVS led to a repression of its expression. In conclusion, these groundbreaking findings underscore the potential of miR-29a in improving the treatment of NAFLD and liver steatofibrosis by inhibiting the MAVS signaling pathway.

Queuine ameliorates impaired mitochondrial function caused by mt-tRNAAsn variants

BackgroundMitochondrial tRNA (mt-tRNA) variants have been found to cause disease. Post-transcriptional queuosine (Q) modifications of mt-tRNA can promote efficient mitochondrial mRNA translation. Q modifications of mt-tRNAAsn have recently been identified. Here, the therapeutic effectiveness of queuine was investigated in cells from patients with mt-tRNAAsn variants.MethodsSix patients (from four families) carrying mt-tRNAAsn variants were included in the study. Queuine levels were quantified by mass spectrometry. Clinical, genetic, histochemical, biochemical, and molecular analysis was performed on muscle tissues and lymphoblastoid cell lines (LCLs) from patients to investigate the pathogenicity of the novel m.5708 C > T variant. The use of queuine in mitigating mitochondrial dysfunction resulting from the mt-tRNAAsn variants was evaluated.ResultsThe variants included the m.5701 delA, m.5708 C > T, m.5709 C > T, and m.5698 G > A variants in mt-tRNAAsn. The pathogenicity of the novel m.5708 C > T variant was confirmed, as demonstrated by a decreased steady-state level of mt-tRNAAsn, mtDNA-encoded protein levels, oxygen consumption rate (OCR), and the respiratory complex activity. Notably, the serum queuine level was significantly reduced in these patients and in vitro queuine supplementation was found to restore the reductions in mitochondrial protein activities, mitochondrial membrane potential, OCR, and increases in reactive oxygen species.ConclusionsThe study not only confirmed the pathogenicity of the m.5708 C > T variant but also explored the therapeutic potential of queuine in individuals with mt-tRNAAsn variants. The recognition of the novel m.5708 C > T variant’s pathogenic nature contributes to our comprehension of mitochondrial disorders. Furthermore, the results emphasize queuine supplementation as a promising approach to enhance the stability of mt-tRNAAsn and rescue mitochondrial dysfunction caused by mt-tRNAAsn variants, indicating potential implications for the development of targeted therapies for patients with mt-tRNAAsn variants.

IARS2 mutations lead to Leigh syndrome with a combined oxidative phosphorylation deficiency

BackgroundLeigh syndrome (LS) is a common mitochondrial disease caused by mutations in both mitochondrial and nuclear genes. Isoleucyl-tRNA synthetase 2 (IARS2) encodes mitochondrial isoleucine-tRNA synthetase, and variants in IARS2 have been reported to cause LS. However, the pathogenic mechanism of IARS2 variants is still unclear.MethodsTwo unrelated patients, a 4-year-old boy and a 5-year-old boy diagnosed with LS, were recruited, and detailed clinical data were collected. The DNA of the patients and their parents was isolated from the peripheral blood for the identification of pathogenic variants using next-generation sequencing and Sanger sequencing. The ClustalW program, allele frequency analysis databases (gnomAD and ExAc), and pathogenicity prediction databases (Clinvar, Mutation Taster and PolyPhen2) were used to predict the conservation and pathogenicity of the variants. The gene expression level, oxygen consumption rate (OCR), respiratory chain complex activity, cellular adenosine triphosphate (ATP) production, mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (ROS) levels were measured in patient-derived lymphocytes and IARS2-knockdown HEK293T cells to evaluate the pathogenicity of the variants.ResultsWe reported 2 unrelated Chinese patients manifested with LS who carried biallelic IARS2 variants (c.1_390del and c.2450G > A from a 4-year-old boy, and c.2090G > A and c.2122G > A from a 5-year-old boy), of which c.1_390del and c.2090G > A were novel. Functional studies revealed that the patient-derived lymphocytes carrying c.1_390del and c.2450G > A variants exhibited impaired mitochondrial function due to severe mitochondrial complexes I and III deficiencies, which was also found in IARS2-knockdown HEK293T cells. The compensatory experiments in vitro cell models confirmed the pathogenicity of IARS2 variants since re-expression of wild-type IARS2 rather than mutant IARS2 could rescue complexes I and III deficiency, oxygen consumption, and cellular ATP content in IARS2 knockdown cells.ConclusionOur results not only expand the gene mutation spectrum of LS, but also reveal for the first time the pathogenic mechanism of IARS2 variants due to a combined deficiency of mitochondrial complexes I and III, which is helpful for the clinical diagnosis of IARS2 mutation-related diseases.

The deubiquitinase USP15 drives malignant progression of gastric cancer through glucose metabolism remodeling

BackgroundUbiquitin-specific protease 15 (USP15) exhibits amplifications in various tumors, including gastric cancer (GC), yet its biological function and mechanisms in GC progression remain elusive.MethodsHere, we established stable USP15 knockdown or overexpression GC cell lines and explored the potential mechanism of USP15 in GC. Besides, we also identified interacting targets of USP15.ResultsUSP15 knockdown significantly impeded cell proliferation, invasion, epithelial-mesenchymal transition, and distal colonization in xenograft models, while enhancing oxaliplatin's antitumor effect. USP15 was involved in ubiquitination modification of glycolytic regulators. Silencing of USP15 suppressed glycolytic activity and impaired mitochondrial functions. Interference with USP15 expression reversed tumor progression and distal colonization in vivo. HKDC1 and IGF2BP3 were found as core interacting targets of USP15, and HKDC1 was identified as a substrate for ubiquitination modification by USP15, whereby USP15 regulated glucose metabolism activity by inhibiting the ubiquitination degradation of HKDC1.ConclusionsOur study unveiled aberrantly high expression of USP15 in GC tissues, correlating with malignant progression and nonresponse to neoadjuvant therapy. USP15 inhibitors, if developed, could be effective in promoting chemotherapy through glucose metabolism remodeling.

Sodium Selenite Induces Autophagy and Apoptosis in Cervical Cancer Cells via Mitochondrial ROS-Activated AMPK/mTOR/FOXO3a Pathway.

Selenium (Se) is an essential trace element known for its significant role in maintaining human health and mitigating disease progression. Selenium and its compounds exhibit high selective cytotoxicity against tumor cells. However, their anti-cervical cancer (CC) effects and underlying mechanisms have not been fully explored. This study found that sodium selenite (SS) inhibits the viability of HeLa and SiHa cells in a dose- and time-dependent manner. Intraperitoneal injection of 3 and 6 mg/kg SS for 14 days in female nude mice significantly inhibited the growth of HeLa cell xenografts without evident hepatotoxicity or nephrotoxicity. RNA sequencing results indicated that the AMP-activated protein kinase (AMPK), Forkhead box protein O (FOXO), and apoptosis signaling pathways are key regulatory pathways in SS's anti-CC effects, and SS's inhibition of HeLa cell proliferation may be related to autophagy and ROS-induced apoptosis. Further research has revealed that SS induces cell autophagy and apoptosis through the AMPK/mTOR/FOXO3a pathway, characterized by the upregulation of p-AMPK/AMPK, FOXO3a, LC3-II, cleaved-caspase3, and cleaved-PARP and the downregulation of p-mTOR/mTOR and p62. Additionally, SS impaired mitochondrial function, including decreased mitochondrial membrane potential, mitochondrial Ca2+ overload, and accumulation of mitochondrial reactive oxygen species (mtROS). Pretreatment with Mitoquinone mesylate (Mito Q) and compound C partially reversed SS-induced apoptosis, autophagy, and proliferation inhibition. Pretreatment with 3-methyladenine (3-MA) enhances SS-induced apoptosis and proliferation inhibition in HeLa cells but reverses these effects in SiHa cells. In summary, SS induces apoptosis, autophagy, and proliferation inhibition in HeLa and SiHa cells through the activation of the AMPK/mTOR/FOXO3a signaling pathway via mtROS. Autophagy activation may be a major risk factor for SS-induced apoptosis in SiHa cells but can protect HeLa cells from SS-induced apoptosis. These findings provide new evidence for understanding the molecular mechanisms underlying SS in potential new drug development for CC.

Loss of DNA glycosylases improves health and cognitive function in a C. elegans model of human tauopathy.

Alzheimer's disease (AD) is a neurodegenerative disorder representing a major burden on families and society. Some of the main pathological hallmarks of AD are the accumulation of amyloid plaques (Aβ) and tau neurofibrillary tangles. However, it is still unclear how Aβ and tau aggregates promote specific phenotypic outcomes and lead to excessive oxidative DNA damage, neuronal cell death and eventually to loss of memory. Here we utilized a Caenorhabditis elegans (C. elegans)model of human tauopathy to investigate the role of DNA glycosylases in disease development and progression. Transgenic nematodes expressing a pro-aggregate form of tau displayed altered mitochondrial content, decreased lifespan, and cognitive dysfunction. Genetic ablation of either of the two DNA glycosylases found in C. elegans, NTH-1 and UNG-1, improved mitochondrial function, lifespan, and memory impairment. NTH-1 depletion resulted in a dramatic increase of differentially expressed genes, which was not apparent in UNG-1 deficient nematodes. Our findings clearly show that in addition to its enzymatic activity, NTH-1 has non-canonical functions highlighting its modulation as a potential therapeutic intervention to tackle tau-mediated pathology.

Excessive Daytime Sleepiness, Inflammation, and Platelet Energy Metabolism in Chronic Stroke Survivors: A Pilot Study.

Excessive daytime sleepiness is a prevalent and sustained symptom that contributes to untoward physiologic and psychologic outcomes among stroke survivors. Mechanisms of excessive daytime sleepiness post-stroke are not fully understood. Chronic systemic inflammation may contribute to impaired mitochondrial functioning and thereby reduce cellular energy metabolism which may contribute to symptoms of excessive daytime sleepiness in stroke survivors. This pilot study aimed to assess the relationship between systemic inflammation and cellular energy metabolism to post-stroke excessive daytime sleepiness. This descriptive pilot study explored the relationship between excessive daytime sleepiness, systemic inflammation, and aerobic energy metabolism of platelets in 22 chronic stroke survivors. The Epworth Sleepiness Scale was used to measure excessive daytime sleepiness. Systemic inflammation was measured by assessing pro-inflammatory cytokines IL-6, IL-1β and TNF-α and the inflammatory marker C-reactive protein. Aerobic energy metabolism was measured by assessing oxygen consumption rates of platelets. Simple linear regression was used to test the influence of oxygen consumption rates and inflammation on excessive daytime sleepiness. Correlations were analyzed using Spearman rho correlation coefficients. Excessive daytime sleepiness was recognized in 27.3% of the sample. Systemic inflammation was associated with excessive daytime sleepiness in women but not men. We found no significant relationship between excessive daytime sleepiness and energy metabolism of platelets. However, all oxygen consumption rates were numerically higher in persons with excessive daytime sleepiness. Systemic inflammation may be related to excessive daytime sleepiness symptoms with a notable effect among women. Future larger studies are needed to further explore the sexually dimorphic relationship of post-stroke excessive daytime sleepiness to systemic inflammation. Numerically higher platelet oxygen consumption rates may indicate higher energy demands for stroke survivors with excessive daytime sleepiness.

Age-related mitophagy regulates orthodontic tooth movement by affecting PDLSCs mitochondrial function and RANKL/OPG.

A thorough comprehension of age-related variances in orthodontic tooth movement (OTM) and bone remodeling response to mechanical force holds significant implications for enhancing orthodontic treatment. Mitophagy plays a crucial role in bone metabolism and various age-related diseases. However, the impact of mitophagy on the bone remodeling process during OTM remains elusive. Using adolescent (6 weeks old) and adult (12 months old) rats, we established OTM models and observed that orthodontic force increased the expression of the mitophagy proteins PTEN-induced putative kinase 1 (PINK1) and Parkin, as well as the number of tartrate-resistant acid phosphatase-positive osteoclasts and osteocalcin-positive osteoblasts. These biological changes were found to be age-related. Invitro, compression force loading promoted PINK1/Parkin-dependent mitophagy in periodontal ligament stem cells (PDLSCs) derived from adolescents (12-16 years old) and adults (25-35 years old). Furthermore, adult PDLSCs exhibited lower levels of mitophagy, impaired mitochondrial function, and a decreased ratio of RANKL/OPG compared to young PDLSCs after compression. Transfection of siRNA confirmed that inhibition of mitophagy in PDLSC resulted in decreased mitochondrial function and reduced RANKL/OPG ratio. Application of mitophagy inducer Urolithin A enhanced bone remodeling and accelerated OTM in rats, while the mitophagy inhibitor Mdivi-1 had the opposite effect. These findings indicate that force-stimulated PDLSC mitophagy contributes to alveolar bone remodeling during OTM, and age-related impairment of mitophagy negatively impacts the PDLSC response to mechanical stimulus. Our findings enhance the understanding of mitochondrial mechanotransduction and offer new targets to tackle current clinical challenges in orthodontic therapy.

THP1-based cybrid cells with various mtDNA mutations differ by the ability to form inflammatory response

Most age-related human diseases are accompanied by chronic inflammation. Modern research is aimed at studying the principles of the formation of the immune response. The reasons why the local inflammatory reaction cannot be resolved and becomes a sluggish chronic form are still unknown. Immune cells secrete cytokines in response to pathogens. To avoid cell death as a result of high concentrations of cytokines and resulting tissue damage, there is a mechanism of innate immune tolerance. Innate immune tolerance involves a decrease in the secretion of proinflammatory cytokines in response to repeated exposure to a pathogen. It is known that mitochondria play an important role in the formation of the immune response. Consequently, impaired mitochondrial function can lead to impaired immune response. To control the quality of mitochondria in the cell, there is a mechanism – mitophagy. Previously, we have created cybrid lines based on the monocytic cell line THP-1. Cybrids were obtained by fusion of THP-1 cells (mitochondria were removed) with platelets from patients. Each of the cybrid lines had the THP-1 nuclear genome and an individual patient’s mitochondrial genome. In our study, we decided to study the ability of cells carrying different mitochondrial genomes to generate a proinflammatory response, as well as to form tolerance in the future. For this purpose, we chose a model of ecdotoxin tolerance. Thus, we stimulated the cybrid lines twice with lipopolysaccharide and then assessed the secretion of the cytokines TNFα, IL-1β, IL-6, IL-8, and CCL2 using ELISA. The cybrids demonstrated two levels of proinflammatory response: high and low. Moreover, cybrids with a high proinflammatory response either did or did not develop tolerance upon repeated stimulation. In our study, cells that differed from each other only in mitochondrial genome demonstrated three types of reactions upon the induction of immune tolerance to LPS. Future studies will improve our understanding of the mechanisms of mitochondrial involvement in pathological processes. It is likely that studies of deficient mitophagy and the role of certain mtDNA mutations in its development will yield promising results.

Irisin-Encapsulated Mitochondria-Targeted Biomimetic Nanotherapeutics for Alleviating Acute Kidney Injury.

Acute kidney injury (AKI) is the sudden decrease in renal function that can be attributed to dysregulated reactive oxygen species (ROS) production and impaired mitochondrial function. Irisin, a type I membrane protein secreted by skeletal muscles in response to physical activity, has been reported to alleviate kidney damage through regulation of mitochondrial biogenesis and oxidative metabolism. In this study, a macrophage membrane-coated metal-organic framework (MCM@MOF) is developed as a nanocarrier for encapsulating irisin to overcome the inherent characteristics of irisin, including a short circulation time, limited kidney-targeting ability, and low membrane permeability. The engineered irisin-mediated biomimetic nanotherapeutics have extended circulation time and enhanced targeting capability toward injured kidneys due to the preservation of macrophage membrane proteins. The irisin-encapsulated biomimetic nanotherapeutics effectively mitigate acute ischemia-reperfusion injury by protecting mitochondrial function and modulating SOD2 levels in renal tubular epithelial cells. The present study provides novel insights to advance the development of irisin as a potential therapeutic approach for AKI.