Impaired Mitochondrial Function Research Articles

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.

Berberine Attenuates Acetamiprid Exposure-Induced Mitochondrial Dysfunction and Apoptosis in Rats via Regulating the Antioxidant Defense System.

Acetamiprid (ACMP) is a neonicotinoid insecticide that poses a significant threat to the environment and mankind. Oxidative stress and mitochondrial dysfunction are considered prime contributors to ACMP-induced toxic effects. Meanwhile, berberine (BBR) a natural plant alkaloid, is a topic of interest because of its therapeutic and prophylactic actions. Therefore, this study evaluated the effects of BBR on ACMP-mediated alterations in mitochondrial functions and apoptosis in rat liver tissue. Male Wistar rats were divided into four groups: (I) control, (II) BBR-treated, (III) ACMP-exposed, and (IV) BBR+ACMP co-treated groups. The doses of BBR (150 mg/kg b.wt) and ACMP (1/10 of LD50, i.e., 21.7 mg/kg b.wt) were given intragastrically for 21 consecutive days. The results showed that the administration of ACMP diminished mitochondrial complex activity, downregulated complex I (ND1 and ND2) and complex IV (COX1 and COX4) subunit mRNA expression, depleted the antioxidant defense system, and induced apoptosis in rat liver. BBR pre-treatment significantly attenuated ACMP-induced mitochondrial dysfunction by maintaining mitochondrial complex activity and upregulating ND1, ND2, COX1, and COX4 mRNA expression. BBR reversed ACMP-mediated apoptosis by diminishing Bax and caspase-3 and increasing the Bcl-2 protein level. BBR also improved the mitochondrial antioxidant defense system by upregulating mRNA expression of PGC-1α, MnSOD, and UCP-2 in rat liver tissue. This study is the first to evaluate the protective potential of BBR against pesticide-induced mitochondrial dysfunction in liver tissue. In conclusion, BBR offers protection against ACMP-induced impairment in mitochondrial functions by maintaining the antioxidant level and modulating the apoptotic cascade.

Sex Differences in Hepatic Inflammation, Lipid Metabolism, and Mitochondrial Function Following Early Lipopolysaccharide Exposure in Epileptic WAG/Rij Rats.

Among the non-communicable neurological diseases, epilepsy is characterized by abnormal brain activity with several peripheral implications. The role of peripheral inflammation in the relationship between seizure development and nonalcoholic fatty liver disease based on sex difference remains still overlooked. Severe early-life infections lead to increased inflammation that can aggravate epilepsy and hepatic damage progression, both related to increased odds of hospitalization for epileptic patients with liver diseases. Here, we induced a post-natal-day 3 (PND3) infection by LPS (1 mg/kg, i.p.) to determine the hepatic damage in a genetic model of young epileptic WAG/Rij rats (PND45). We evaluated intra- and inter-gender differences in systemic and liver inflammation, hepatic lipid dysmetabolism, and oxidative damage related to mitochondrial functional impairment. First, epileptic rats exposed to LPS, regardless of gender, displayed increased serum hepatic enzymes and altered lipid profile. Endotoxin challenge triggered a more severe inflammatory and immune response in male epileptic rats, compared to females in both serum and liver, increasing pro-inflammatory cytokines and hepatic immune cell recruitment. Conversely, LPS-treated female rats showed significant alterations in systemic and hepatic lipid profiles and reduced mitochondrial fatty acid oxidation. The two different sex-dependent mechanisms of LPS-induced liver injury converge in increased ROS production and related mitochondrial oxidative damage in both sexes. Notably, a compensatory increase in antioxidant defense was evidenced only in female rats. Our study with a translational potential demonstrates, for the first time, that early post-natal infections in epileptic rats induced or worsened hepatic disorders in a sex-dependent manner, amplifying inflammation, lipid dysmetabolism, and mitochondrial impairment.

Evaluation of Unsaponifiable Fraction of Avocado Oil on Liver and Kidney Mitochondrial Function in Rats Fed a High-Fat and High-Carbohydrate Diet.

High-fat and high-carbohydrate (HF-HC) diets induce metabolic syndrome via mitochondrial dysfunction and oxidative stress. We have previously shown that this may be prevented by avocado oil, a source of bioactive molecules with antioxidant properties. However, it is unknown if these effects are mediated by the unsaponifiable fraction of avocado oil (UFAO). Thus, we tested if this fraction improves glucose metabolism, bioenergetics and oxidative stress in mitochondria from the kidney and liver of rats fed an HF-HC diet. We found that 12 weeks of an HF-HC diet impaired glucose utilization and increased insulin resistance, which was prevented by UFAO administration. The HF-HC diet decreased respiration, membrane potential and electron transport chain (ETC) function in liver and kidney mitochondria. These mitochondrial dysfunctions were prevented by UFAO intake. Unexpectedly, UFAO increased ROS levels in the mitochondria of control animals and did not decrease them in rats with an HF-HC diet; however, UFAO protects liver and kidney mitochondria from iron-induced oxidative stress. These findings suggest that impairments in glucose metabolism and mitochondrial function by an HF-HC diet may be prevented by UFAO, without decreasing ROS generation but protecting mitochondria from oxidative damage.

Abstract Tu112: The Outer Mitochondrial Membrane Protein Mtch2 Regulates Cardiac Metabolic Homeostasis and Body Mass

Introduction: MTCH2 is an outer mitochondrial membrane protein insertase and variants in MTCH2 associate with human heart failure and obesity. Hypothesis: Lower levels of MTCH2 predispose the heart to stress. Methods and Results: Cardiomyocyte-specific Mtch2 KO ( cMtch2 KO) mice were generated and develop systolic dysfunction accompanied by increased fibrosis and elevation of heart failure markers ( n =6). Prior to the development of cardiac dysfunction male cMtch2 KO mice maintain a leaner body mass compared to controls, consistent with the idea that cardiac MTCH2 drives whole body energy utilization. We hypothesize the increased energetic demand of maintaining cardiac function in younger animals shifts energy expenditure and results in lower fat mass. We found that young, pre-cardiomyopathic cMtch2 KO mice were sensitized to stress. When young cMtch2 KO mice were challenged to an acute dosing regimen of isoproterenol, compared to controls, hearts from cMtch2 KO mice failed to respond with physiological hypertrophy and animals could not maintain body mass ( n =7). We assessed mitochondrial function in cMtch2 KO mice. Isolated cMtch2 KO cardiomyocytes loaded with Mitotracker green and TMRE had reduced mitochondrial membrane potential compared to control ( n =20 cells/mouse, 3 mice/group). In the presence of glucose, oxygen consumption rates were reduced in cMtch2 KO heart tissue ( n =6), and targeted metabolomics of cMtch2 KO ventricle exhibited an accumulation of palmitate ( n =4), indicating cMtch2 KO hearts do not efficiently utilize glucose and fatty acids. To identify changes in the mitochondrial proteome we performed mass spectrometry on isolated mitochondria from control and cMtch2 KO mice ( n =4). Overall, proteins associated with fatty acid beta oxidation and pyruvate metabolism were reduced in abundance in cMtch2 KO hearts compared to control. Additionally, three potential insertase target proteins were reduced, confirming a critical role for MTCH2 in mitochondrial health. Conclusion: MTCH2 is vital for maintaining normal mitochondrial function. Reduction of MTCH2 sensitizes the heart to stress, resulting in impaired mitochondrial, sarcomere, and global heart function with effects on body composition.

Research Progress on Mechanisms and Treatment of Sepsis-Induced Myocardial Dysfunction.

Sepsis is a syndrome of organ dysfunction caused by a dysregulated immune response to infection, with high morbidity and mortality. At present, there have been many advances in the study of its pathogenesis, especially the cardiac dysfunction caused by sepsis, namely sepsis-induced myocardial dysfunction, SIMD, which has received widespread attention. The mechanisms of SIMD mainly include excessive release of inflammatory mediators, impaired mitochondrial function, autophagy, apoptosis and myocardial dysfunction. This article reviews the pathogenesis of SIMD and elaborates on the progress in its treatment, aiming to improve the prognosis of patients with SIMD and sepsis.

Two Sides of Triglycerides in Atherogenesis: An Essential Contributor

Atherosclerosis is chronic arterial wall damage, which often results in cardiovascular disease development. Since atherosclerosis is almost asymptomatic, it is difficult to detect this condition, but it is even more difficult to deal with the consequences. The reasons for the development of atherosclerosis are still not completely clear, but the mechanisms involved in atherogenesis are known. Among them, lipid metabolism alterations, oxidative stress, as well as impaired mitochondrial function take pride of place. In our review, we want to dwell in more detail on such a component as lipid metabolism disorders. In particular, triglycerides, their levels, and influence on the development of the disease. Triglycerides provide the second-largest source of energy. In the context of atherosclerosis, the question arises, is an increase in the level of triglycerides in the blood a cause, a biomarker, or a consequence of the processes accompanying atherogenesis?

Neuronal A2A receptor exacerbates synapse loss and memory deficits in APP/PS1 mice.

Early pathological upregulation of adenosine A2A receptors (A2ARs), one of the caffeine targets, by neurons is thought to be involved in the development of synaptic and memory deficits in Alzheimer's disease (AD) but mechanisms remain ill-defined. To tackle this question, we promoted a neuronal upregulation of A2AR in the hippocampus of APP/PS1 mice developing AD-like amyloidogenesis. Our findings revealed that the early upregulation of A2AR in the presence of an ongoing amyloid pathology exacerbates memory impairments of APP/PS1 mice. These behavioural changes were not linked to major change in the development of amyloid pathology but rather associated with increased phosphorylated tau at neuritic plaques. Moreover, proteomic and transcriptomic analyses coupled with quantitative immunofluorescence studies indicated that neuronal upregulation of the receptor promoted both neuronal and non-neuronal autonomous alterations, i.e. enhanced neuroinflammatory response but also loss of excitatory synapses and impaired neuronal mitochondrial function, presumably accounting for the detrimental effect on memory. Overall, our results provide compelling evidence that neuronal A2AR dysfunction, as seen in the brain of patients, contributes to amyloid-related pathogenesis and underscores the potential of A2AR as a relevant therapeutic target for mitigating cognitive impairments in this neurodegenerative disorder.

Avermectin induced vascular damage in zebrafish larvae: association with mitochondria-mediated apoptosis and VEGF/Notch signaling pathway

Avermectin is a highly effective insecticide that has been widely used in agriculture since the 1990s. In recent years, the safety of avermectin for non-target organisms has received much attention. The vasculature is important organs in the body and participate in the composition of other organs. However, studies on the vascular safety of avermectin are lacking. The vasculature of zebrafish larvae is characterized by ease of observation and it is a commonly used model for vascular studies. Therefore, zebrafish larvae were used to explore the potential risk of avermectin on the vasculature. The results showed that avermectin induced vascular damage throughout the body of zebrafish larvae, including the head, eyes, intestine, somite, tail and other vasculature. The main forms of damage are reduction in vascular diameter, vascular area and vascular abundance. Meanwhile, avermectin induced a decrease in the number of endothelial cells and apoptosis within the vasculature. In addition, vascular damage may be related to impairment of mitochondrial function and mitochondria-mediated apoptosis. Finally, exploration of the molecular mechanisms revealed abnormal alterations in the expression of genes related to the VEGF/Notch signaling pathway. Therefore, the VEGF/Notch signaling pathway may be an important mechanism for avermectin-induced vascular damage in zebrafish larvae. This study demonstrates the vascular toxicity of avermectin in zebrafish larvae and reveals the possible molecular mechanism, which would hopefully draw more attention to the safety of avermectin in non-target organisms.

Impairment of Renal and Hematopoietic Stem/Progenitor Cell Compartments in Frailty Syndrome: Link with Oxidative Stress, Plasma Cytokine Profiles and Nuclear DNA Damage.

Frailty is an age-related syndrome that drives multiple physiological system impairments in some older adults, and its pathophysiological mechanisms remain unclear. We evaluated whether frailty-related biological processes could impair stem cell compartments, specifically the renal stem compartment, given that kidney dysfunctions are frequent in frailty. A well-characterized in vitro nephrosphere model of human adult renal stem/progenitor cells has been instrumental to and was appropriate for verifying this hypothesis in our current research. Evaluating the effects of plasma from older individuals with frailty (frail plasma) on allogeneic renal stem/progenitor cells, we showed significant functional impairment and nuclear DNA damage in the treated cells of the renal stem compartment. The analysis of the frail plasma revealed mitochondrial functional impairment associated with the activation of oxidative stress and a unique inflammatory mediator profile in frail individuals. In addition, the plasma of frail subjects also contained the highest percentage of DNA-damaged autologous circulating hematopoietic progenitor/stem cells. The integration of both molecular and functional data obtained allowed us to discern patterns associated with frailty status, irrespective of the comorbidities present in the frail individuals. The data obtained converged toward biological conditions that in frailty caused renal and hematopoietic impairment of stem cells, highlighting the possibility of concomitant exhaustion of several stem compartments.

SPAG7 deletion causes intrauterine growth restriction, resulting in adulthood obesity and metabolic dysfunction.

From a forward mutagenetic screen to discover mutations associated with obesity, we identified mutations in the Spag7 gene linked to metabolic dysfunction in mice. Here, we show that SPAG7 KO mice are born smaller and develop obesity and glucose intolerance in adulthood. This obesity does not stem from hyperphagia, but a decrease in energy expenditure. The KO animals also display reduced exercise tolerance and muscle function due to impaired mitochondrial function. Furthermore, SPAG7-deficiency in developing embryos leads to intrauterine growth restriction, brought on by placental insufficiency, likely due to abnormal development of the placental junctional zone. This insufficiency leads to loss of SPAG7-deficient fetuses in utero and reduced birth weights of those that survive. We hypothesize that a 'thrifty phenotype' is ingrained in SPAG7 KO animals during development that leads to adult obesity. Collectively, these results indicate that SPAG7 is essential for embryonic development and energy homeostasis later in life.

Dysfunction of Mitochondrial Dynamics Induces Endocytosis Defect and Cell Damage in Drosophila Nephrocytes.

Mitochondria are crucial for cellular ATP production. They are highly dynamic organelles, whose morphology and function are controlled through mitochondrial fusion and fission. The specific roles of mitochondria in podocytes, the highly specialized cells of the kidney glomerulus, remain less understood. Given the significant structural, functional, and molecular similarities between mammalian podocytes and Drosophila nephrocytes, we employed fly nephrocytes to explore the roles of mitochondria in cellular function. Our study revealed that alterations in the Pink1-Park (mammalian PINK1-PRKN) pathway can disrupt mitochondrial dynamics in Drosophila nephrocytes. This disruption led to either fragmented or enlarged mitochondria, both of which impaired mitochondrial function. The mitochondrial dysfunction subsequently triggered defective intracellular endocytosis, protein aggregation, and cellular damage. These findings underscore the critical roles of mitochondria in nephrocyte functionality.

Combined inhibition of EZH2 and CDK4/6 perturbs endoplasmic reticulum-mitochondrial homeostasis and increases antitumor activity against glioblastoma

Here, we show that combined use of the EZH2 inhibitor GSK126 and the CDK4/6 inhibitor abemaciclib synergistically enhances antitumoral effects in preclinical GBM models. Dual blockade led to HIF1α upregulation and CalR translocation, accompanied by massive impairment of mitochondrial function. Basal oxygen consumption rate, ATP synthesis, and maximal mitochondrial respiration decreased, confirming disrupted endoplasmic reticulum-mitochondrial homeostasis. This was paralleled by mitochondrial depolarization and upregulation of the UPR sensors PERK, ATF6α, and IRE1α. Notably, dual EZH2/CDK4/6 blockade also reduced 3D-spheroid invasion, partially inhibited tumor growth in ovo, and led to impaired viability of patient-derived organoids. Mechanistically, this was due to transcriptional changes in genes involved in mitotic aberrations/spindle assembly (Rb, PLK1, RRM2, PRC1, CENPF, TPX2), histone modification (HIST1H1B, HIST1H3G), DNA damage/replication stress events (TOP2A, ATF4), immuno-oncology (DEPDC1), EMT-counterregulation (PCDH1) and a shift in the stemness profile towards a more differentiated state. We propose a dual EZH2/CDK4/6 blockade for further investigation.

The predictive value of peripheral blood cell mitochondrial gene expression in identifying the prognosis in pediatric sepsis at preschool age.

Sepsis represents a severe manifestation of infection often accompanied by metabolic disorders and mitochondrial dysfunction. Notably, mitochondrial DNA copy number (mtDNA-CN) and the expression of specific mitochondrial genes have emerged as sensitive indicators of mitochondrial function. To investigate the utility of mitochondrial gene expression in peripheral blood cells for distinguishing severe infections and predicting associated outcomes, we conducted a prospective cohort study. We established a prospective cohort comprising 74 patients with non-sepsis pneumonia and 67 cases of sepsis induced by respiratory infections, aging from 2 to 6 years old. We documented corresponding clinical data and laboratory information and collected blood samples upon initial hospital admission. Peripheral blood cells were promptly isolated, and both total DNA and RNA were extracted. We utilized absolute quantification PCR to assess mtDNA-CN, as well as the expression levels of mt-CO1, mt-ND1, and mt-ATP6. Subsequently, we extended these comparisons to include survivors and non-survivors among patients with sepsis using univariate and multivariate analyses. Receiver operating characteristic (ROC) curves were constructed to assess the diagnostic potential. The mtDNA-CN in peripheral blood cells was significantly lower in the sepsis group. Univariate analysis revealed a significant reduction in the expression of mt-CO1, mt-ND1, and mt-ATP6 in patients with sepsis. However, multivariate analysis did not support the use of mitochondrial function in peripheral blood cells for sepsis diagnosis. In the comparison between pediatric sepsis survivors and non-survivors, univariate analysis indicated a substantial reduction in the expression of mt-CO1, mt-ND1, and mt-ATP6 among non-survivors. Notably, total bilirubin (TB), mt-CO1, mt-ND1, and mt-ATP6 levels were identified as independent risk factors for sepsis-induced mortality. ROC curves were then established for these independent risk factors, revealing areas under the curve (AUCs) of 0.753 for TB (95% CI 0.596-0.910), 0.870 for mt-CO1 (95% CI 0.775-0.965), 0.987 for mt-ND1 (95% CI 0.964-1.000), and 0.877 for mt-ATP6 (95% CI 0.793-0.962). MtDNA-CN and mitochondrial gene expression are closely linked to the severity and clinical outcomes of infectious diseases. Severe infections lead to impaired mitochondrial function in peripheral blood cells. Notably, when compared to other laboratory parameters, the expression levels of mt-CO1, mt-ND1, and mt-ATP6 demonstrate promising potential for assessing the prognosis of pediatric sepsis.

Targeting Mitochondrial Dysfunction and Reactive Oxygen Species for Neurodegenerative Disease Treatment.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases, and they affect millions of people worldwide, particularly older individuals. Therefore, there is a clear need to develop novel drug targets for the treatment of age-related neurodegenerative diseases. Emerging evidence suggests that mitochondrial dysfunction and reactive oxygen species (ROS) generation play central roles in the onset and progression of neurodegenerative diseases. Mitochondria are key regulators of respiratory function, cellular energy adenosine triphosphate production, and the maintenance of cellular redox homeostasis, which are essential for cell survival. Mitochondrial morphology and function are tightly regulated by maintaining a balance among mitochondrial fission, fusion, biogenesis, and mitophagy. In this review, we provide an overview of the main functions of mitochondria, with a focus on recent progress highlighting the critical role of ROS-induced oxidative stress, dysregulated mitochondrial dynamics, mitochondrial apoptosis, mitochondria-associated inflammation, and impaired mitochondrial function in the pathogenesis of age-related neurodegenerative diseases, such as AD and PD. We also discuss the potential of mitochondrial fusion and biogenesis enhancers, mitochondrial fission inhibitors, and mitochondria-targeted antioxidants as novel drugs for the treatment of these diseases.

PDZK1 protects against mechanical overload-induced chondrocyte senescence and osteoarthritis by targeting mitochondrial function

Mechanical overloading and aging are two essential factors for osteoarthritis (OA) development. Mitochondria have been identified as a mechano-transducer situated between extracellular mechanical signals and chondrocyte biology, but their roles and the associated mechanisms in mechanical stress-associated chondrocyte senescence and OA have not been elucidated. Herein, we found that PDZ domain containing 1 (PDZK1), one of the PDZ proteins, which belongs to the Na+/H+ Exchanger (NHE) regulatory factor family, is a key factor in biomechanically induced mitochondrial dysfunction and chondrocyte senescence during OA progression. PDZK1 is reduced by mechanical overload, and is diminished in the articular cartilage of OA patients, aged mice and OA mice. Pdzk1 knockout in chondrocytes exacerbates mechanical overload-induced cartilage degeneration, whereas intraarticular injection of adeno-associated virus-expressing PDZK1 had a therapeutic effect. Moreover, PDZK1 loss impaired chondrocyte mitochondrial function with accumulated damaged mitochondria, decreased mitochondrion DNA (mtDNA) content and increased reactive oxygen species (ROS) production. PDZK1 supplementation or mitoubiquinone (MitoQ) application alleviated chondrocyte senescence and cartilage degeneration and significantly protected chondrocyte mitochondrial functions. MRNA sequencing in articular cartilage from Pdzk1 knockout mice and controls showed that PDZK1 deficiency in chondrocytes interfered with mitochondrial function through inhibiting Hmgcs2 by increasing its ubiquitination. Our results suggested that PDZK1 deficiency plays a crucial role in mediating excessive mechanical load-induced chondrocyte senescence and is associated with mitochondrial dysfunction. PDZK1 overexpression or preservation of mitochondrial functions by MitoQ might present a new therapeutic approach for mechanical overload-induced OA.