Cell Biology of the Mitochondrion

Mitochondrial dysfunction: the hidden catalyst in chronic kidney disease progression

Chronic kidney disease (CKD) represents a global health epidemic, with approximately one-third of affected individuals ultimately necessitating renal replacement therapy or transplantation. The kidney, characterized by its exceptionally high energy demands, exhibits significant sensitivity to alterations in energy supply and mitochondrial function. In CKD, a compromised capacity for mitochondrial ATP synthesis has been documented. As research advances, the multifaceted roles of mitochondria, extending beyond their traditional functions in oxygen sensing and energy production, are increasingly acknowledged. Empirical studies have demonstrated a strong association between mitochondrial dysfunction and the pathogenesis of fibrosis and cellular apoptosis in CKD. Targeting mitochondrial dysfunction holds substantial therapeutic promise, with emerging insights into its epigenetic regulation in CKD, particularly involving non-coding RNAs and DNA methylation. This article presents a comprehensive review of contemporary research on mitochondrial dysfunction in relation to the onset and progression of CKD. It elucidates the associated molecular mechanisms across various renal cell types and proposes novel research avenues for CKD treatment.

Bioactive peptides PDBSN improve mitochondrial function and suppression the oxidative stress in human adiposity cells

Mitochondria are essential for generating cellular energy and are significant in the pathogenesis of obesity. Human visceral and subcutaneous preadipocytes (HPA-v and HPA-s) were cultured into mature adipocytes. Intracellular triglyceride (TG) content was assessed using oil-red O staining and tissue triglyceride determination. Mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) levels were measured with fluorescent indicators. Gene and protein expression related to mitochondrial biogenesis were analyzed by real-time quantitative PCR and Western blotting. Morphological changes were observed via electron microscopy. Results show that PDBSN significantly increased MMP while decreasing TG and ROS levels. The transcription and protein levels of PGC1-α and MTFA were upregulated, and mitochondrial fusion and fission markers (MFN1, MFN2, NRF1, DRP1) were elevated. Additionally, PDBSN enhanced maximum respiratory capacity and reduced ROS. These findings suggest that PDBSN improves mitochondrial function, providing insights for obesity treatment and metabolic disease management.

The ADCK Kinase Family: Key Regulators of Bioenergetics and Mitochondrial Function and Their Implications in Human Cancers

AarF domain-containing kinases (ADCKs) are a family of putative mitochondrial proteins that have been implicated in various aspects of mitochondrial function and cellular metabolism. Mitochondria play a crucial role in cellular bioenergetics, primarily in adenosine triphosphate (ATP) production, while also regulating metabolism, thermogenesis, apoptosis, and reactive oxygen species (ROS) generation. Evidence suggests that the ADCK family of proteins is involved in maintaining mitochondrial architecture and homeostasis. In detail, these proteins are believed to play a role in processes such as coenzyme Q biosynthesis, energy production, and cellular metabolism. There are five known isoforms of ADCK (ADCK1-ADCK5), some of which have similar activities, and each also has its own unique biological functions. Dysregulation or mutations in specific ADCK isoforms have been linked to several pathological conditions, including multiple human cancers, primary coenzyme Q10 (CoQ10) deficiency, and metabolic disorders. This review surveys the current body of peer-reviewed research on the ADCK protein family, incorporating data from the primary literature, case studies, and experimental studies conducted in both in vitro and in vivo systems. It also draws on existing review articles and known published findings to provide a comprehensive overview of the functional roles, disease associations, and molecular mechanisms of ADCK proteins. Further in-depth research on ADCK proteins has the potential to unlock critical insights into their precise mechanisms. This could pave the way for identifying new therapeutic targets for mitochondrial and metabolic-related diseases, as well as for advancing cancer treatment strategies.

Artemether Improves Aβ1-42-Induced Mitochondrial Dysfunction and Protects Against Blood-Brain Barrier Damage Through Activating the CAMKK2/AMPK/PGC1α Signaling Pathway

Alzheimer's disease (AD) represents the most common manifestation of dementia. Cerebrovascular dysfunction constitutes one of the initial events in the pathogenic process of AD. Recently, our research group has reported that artemether, a first-line antimalarial drug approved by the FDA, exhibits a neuroprotective property. Nevertheless, the impact of artemether on cerebrovascular dysfunction, along with its underlying mechanisms, still awaits comprehensive elucidation. This study systematically investigated the neuroprotective effects of artemether against Aβ1-42-induced injury in brain microvascular endothelial cells and explored the underlying molecular mechanisms. Our findings demonstrate that artemether potently mitigates Aβ1-42-mediated cytotoxicity and endothelial barrier dysfunction in mouse brain microvascular endothelial cells. Moreover, artemether attenuated blood-brain barrier disruption by upregulating tight junction proteins OCLN, CLDN-5, and ZO-1. Further studies revealed that artemether treatment improved elevated ROS levels, the dissipation of mitochondrial membrane potential, and the decrease of ATP content. Immunoblotting analysis demonstrated that artemether stimulated the CAMKK2-AMPK kinase and its downstream target PGC1α. In addition, the blockage of the CAMKK2/AMPK/PGC1α pathway by inhibitor STO-609, Compound C, or knocking down the expression level of PGC1α with sgRNA significantly attenuated the neuroprotective activity of artemether. These results indicate the essential role of the CAMKK2/AMPK/PGC1α pathway in the protective effect of artemether in mouse brain microvascular endothelial cells. Similar results were obtained in Aβ1-42-treated human brain microvascular endothelial cells. In the AD mice model, we found that artemether treatment increased the expression level of ZO-1, CLDN-5, and OCLN of the AD mice model. Collectively, these findings demonstrate that artemether exerts neuroprotection against Aβ1-42-induced injury in brain microvascular endothelial cells through activation of the CAMKK2/AMPK/PGC1α signaling axis, which supports the protective effect of artemether in the prevention and treatment of AD through improving cerebrovascular dysfunction.

Neurotoxicity of Realgar: Crosstalk Between UBXD8-DRP1-Regulated Mitochondrial Fission and PINK1-Parkin-Mediated Mitophagy

Realgar is a toxic mineral medicine containing arsenic that is present in many traditional Chinese medicines. It has been reported that the abuse of drugs containing realgar has potential neurotoxicity, but its mechanism of toxicity has not been fully clarified. In this study, we demonstrated that arsenic in realgar promoted mitochondrial fission via UBXD8-mediated DRP1 translocation to the mitochondria and activated mitophagy via PINK1-Parkin, resulting in mitochondrial dysfunction and nerve cell death in the rat cortex. We used PC12 cells and treated them with inorganic arsenic (iAs). Mdivi-1, a mitochondrial fission inhibitor, and the siRNA UBXD8 or PINK1 were used as interventions to verify the precise mechanism by which arsenic affects realgar-induced mitochondrial instability. The results revealed that the arsenic in realgar accumulated in the brain and led to neurobehavioral abnormalities in the rats. We demonstrated that arsenic in realgar-induced high expression of UBXD8 promoted the translocation of DRP1 to the mitochondria, where it underwent phosphorylation, which led to the over-fission of the mitochondria and mitochondria-mediated apoptosis. Moreover, the over-fission of the mitochondria activates mitophagy, which is self-protective but only partially alleviates apoptosis and mitochondria dysfunction. Our findings revealed the crosstalk between mitochondrial fission and mitophagy in realgar-induced neurotoxicity. These results highlight the role of the transposition of DRP1 by UBXD8 in realgar-induced mitochondrial dysfunction and provide new ideas and data for the study of the mechanism of realgar-induced neurotoxicity.

Natural Selection as the Primary Driver of Codon Usage Bias in the Mitochondrial Genomes of Three Medicago Species

OBJECTIVES

Codon usage bias is a fundamental feature of gene expression that can influence evolutionary processes and genetic diversity. This study aimed to investigate the mitochondrial codon usage characteristics and their driving forces in three Medicago species: Medicago polymorpha, Medicago sativa, and Medicago truncatula.

METHODS

The complete mitochondrial genome sequences of the three species were downloaded from GenBank, and 21 shared coding sequences were screened. Codon usage patterns were analyzed using CodonW 1.4.2 and CUSP software. Key parameters, including the relative synonymous codon usage (RSCU), effective number of codons (ENC), codon adaptation index (CAI), codon bias index (CBI), and frequency of optimal codons (Fop), were calculated. Phylogenetic trees and RSCU clustering maps were constructed to explore evolutionary relationships.

RESULTS

The GC contents of the mitochondrial genomes followed the order of GC1 > GC2 > GC3. ENC values averaged above 35, while CAI, CBI, and Fop values ranged from 0.160 to 0.161, -0.078 to -0.076, and 0.362 to 0.363, respectively, indicating a weak preference for codons ending with A/U. Correlation and neutrality analyses suggested that codon usage bias was influenced by both mutation pressure and natural selection, with natural selection being the dominant factor. Fifteen optimal codons, predominantly ending with A/U, were identified. Phylogenetic analysis confirmed the close relationship among the three Medicago species, consistent with traditional taxonomy, whereas the RSCU clustering did not align with the phylogenetic relationships.

CONCLUSIONS

This study provides insights into the mitochondrial codon usage patterns and their evolutionary determinants in Medicago species, highlighting the predominant role of natural selection in shaping codon usage bias. The findings offer a foundation for comparative genomic studies and evolutionary analyses and may be beneficial for improving genetic engineering and breeding programs of Medicago species.

Involvement of Oxidative Stress in Mitochondrial Abnormalities During the Development of Heart Disease

Background: Several mitochondrial abnormalities such as defective energy production, depletion of energy stores, Ca2+ accumulation, generation of reactive oxygen species, and impaired intracellular signaling are associated with cardiac dysfunction during the development of different heart diseases. Methods: A narrative review was compiled by a search for applicable literature in MEDLINE via PubMed. Results: Mitochondria generate ATP through the processes of electron transport and oxidative phosphorylation, which is used as energy for cardiac contractile function. Mitochondria, in fact, are the key subcellular organelle for the regulation of intracellular Ca2+ concentration and are considered to serve as a buffer to maintain Ca2+ homeostasis in cardiomyocytes. However, during the development of heart disease, the excessive accumulation of intracellular Ca2+ results in mitochondria Ca2+-overload, which, in turn, impairs mitochondrial energy production and induces cardiac dysfunction. Mitochondria also generate reactive oxygen species (ROS), including superoxide anion radicals and hydroxyl radicals as well as non-radical oxidants such as hydrogen peroxide, which promote lipid peroxidation and the subsequent disturbance of Ca2+ homeostasis, cellular damage, and death. Conclusion: These observations support the view that both oxidative stress and intracellular Ca2+-overload play a critical role in mitochondrial disruption during the pathogenesis of different cardiac pathologies.

Heat shock transcription factor 2 reduces mitochondrial pathway apoptosis in intestinal epithelial cells by inhibiting the increase in mitochondrial membrane permeability in ulcerative colitis

The destruction of intestinal mucosal mechanical barrier homeostasis caused by excessive apoptosis of intestinal epithelial cells (IECs) is an important reason for the occurrence and development of ulcerative colitis (UC). The increase in mitochondrial membrane permeability caused by the opening of the mitochondrial membrane permeability transition pore (mPTP) is a key link in the initiation of mitochondrial pathway apoptosis. Our previous studies revealed that heat shock transcription factor 2 (HSF2), which is highly expressed in the intestinal mucosa of UC patients, can inhibit the expression of the cytochrome C (Cyto-C)/Caspase-9/Caspase-3 proteins in the mitochondrial pathway of apoptosis, but the regulatory mechanism is unknown. It has been reported that heat shock proteins regulated by heat shock transcription factors are closely related to mPTP opening. Therefore, we hypothesized that HSF2 affects mitochondrial pathway apoptosis in IECs by regulating mPTP opening. In this study, we altered the level of HSF2 in Caco-2 cells by lentivirus transfection to explore the changes in the mitochondrial membrane permeability of Caco-2 cells in an inflammatory environment. Subsequently, the mPTP agonist atractylorhizin (Atr) and inhibitor cyclosporine A (CsA) were used to clarify the regulatory effects of HSF2 on mPTP and the Cyto-C/Caspase-9/Caspase-3 pathways. Our study confirmed for the first time that HSF2 plays a protective role in UC by inhibiting mPTP opening, the increase in mitochondrial membrane permeability and the activation of the mitochondrial-mediated apoptosis pathway in IECs.

Identifying blood mitochondrial DNA copy number as a biomarker for development of neurodegenerative diseases: Evidence from Mendelian randomization analysis

Mitochondrial dysfunction has been associated with neurodegenerative diseases (NDDs). This study aimed to explore the association between blood mitochondrial DNA copy number (mtDNA-CN) and development of NDDs. This study was based on two-sample Mendelian randomization (MR) analysis. The genome wide association study (GWAS) data of NDDs including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), age-related macular degeneration (AMD), multiple sclerosis (MS), Parkinson's disease (PD), primary open-angle glaucoma (POAG), and vascular dementia (VD) was obtained from FinnGen consortium. Inverse-variance weighted (IVW) was applied as the primary approach for MR estimation. MR results revealed that blood mtDNA-CN exhibited a significant relationship with the incidence of AD (IVW-P = 0.011, odds ratio [OR] = 0.65) and AMD (IVW-P = 0.038, OR = 0.64). However, there was no significant association observed between blood mtDNA-CN and other NDDs (IVW-P > 0.05). Our findings supported the relationship between mitochondrial dysfunction and development of AD and AMD, and that blood mtDNA-CN may serve as a potential biomarker for the incidence of these two NDDs.

Combined transcriptomics and metabolomics analyses reveal the molecular mechanism of heat tolerance in Pichia kudriavzevii

Introduction

Pichia kudriavzevii is a prevalent non-Saccharomyces cerevisiae yeast in baijiu brewing. The aim of this study was to isolate a high temperature resistant Pichia kudriavzevii strain from the daqu of strong flavor baijiu and to elucidate its molecular mechanism.

Methods

Growth activity was assessed at temperatures of 37°C, 40°C, 45°C, and 50°C. Morphological changes were observed by scanning electron microscopy at 37°C, 45°C, and 50°C. Subsequent analysis of the transcriptomics and metabolomics was undertaken to elucidate the molecular mechanism of heat tolerance.

Results

The strain was able to tolerate high temperature of 50°C, undergoing substantial morphological alterations. Gene ontology (GO) analysis of the transcriptomics revealed that differentially expressed genes (DEGs) were enriched in pathways such as ATP biosynthesis process and mitochondrion; Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that DEGs were up regulated in oxidative phosphorylation. Utilising liquid chromatograph-mass spectrometer, a total of 463 cationic differential metabolites and 352 anionic differential metabolites were detected and screened for differential substances that were closely related to heat tolerance (NAD+ and ADP); KEGG analysis showed that metabolites were up regulated in purine metabolism. Furthermore, correlation analyses of transcriptomics-metabolomics demonstrated a strong positive correlation between the metabolites NAD+ and ADP, and multiple DEGs of the oxidative phosphorylation pathway.

Discussion

These results suggest that the heat tolerant strain can be able to counteract high temperature environment by up regulating energy metabolism (especially oxidative phosphorylation) to increase ATP production.

Mitochondrial Dysfunction-Molecular Mechanisms and Potential Treatment approaches of Hepatocellular Carcinoma

Primary liver cancer (PLC), also known as hepatocellular carcinoma (HCC), is a common type of malignant tumor of the digestive system. Its pathological form has a significant negative impact on the patients' quality of life and ability to work, as well as a significant financial burden on society. Current researches had identified chronic hepatitis B virus infection, aflatoxin B1 exposure, and metabolic dysfunction-associated steatotic liver disease (MASLD) as the main causative factors of HCC. Numerous variables, including inflammatory ones, oxidative stress, apoptosis, autophagy, and others, have been linked to the pathophysiology of HCC. On the other hand, autoimmune regulation, inflammatory response, senescence of the hepatocytes, and mitochondrial dysfunction are all closely related to the pathogenesis of HCC. In fact, a growing number of studies have suggested that mitochondrial dysfunction in hepatocytes may be a key factor in the pathogenesis of HCC. In disorders linked to cancer, mitochondrial dysfunction has gained attention in recent 10 years. As the primary producer of adenosine triphosphate (ATP) in liver cells, mitochondria are essential for preserving cell viability and physiological processes. By influencing multiple pathological processes, including mitochondrial fission/fusion, mitophagy, cellular senescence, and cell death, mitochondrial dysfunction contributes to the development of HCC. We review the molecular mechanisms of HCC-associated mitochondrial dysfunction and discuss new directions for quality control of mitochondrial disorders as a treatment for HCC.

The immune response and autophagy of Macrobrachium rosenbergii against Aeromonas veronii infection

Aeromonas is a bacterial pathogen that causes significant economic losses in the Macrobrachium rosenbergii industry. This study evaluated the transcriptome analysis of M. rosenbergii infected with A. veronii and examined the gene expression patterns associated with immunity in the gills, muscles, intestines, and hepatopancreas. Specifically, 47,988 unigenes and 15,604 differentially expressed genes (DEGs) were identified. The immune-related DEGs were primarily enriched in 20 innate immune signaling pathways, including the NOD-like receptor, Toll-like receptor, and RIG-I-like receptor signaling pathways, etc., as determined by KEGG enrichment analysis. Notably, autophagy-related genes ATG5, ATG12, ATG16L1, and ATG8 were enriched in the NOD-like receptor signaling pathways. Moreover, ATG12, ATG16L1, and ATG8 exhibited significantly up-regulated expression to varying degrees in the hepatopancreas, gills, muscles, and intestines at 12, 24, 36, and 48 h post-infection (hpi). In addition, many autolysosomes were observed in hepatopancreas cells of infected prawns using transmission electron microscopy (TEM). Ultimately, we identified the autophagy-related genes implicated in the immune response of M. rosenbergii, offering a theoretical foundation for elucidating the role of autophagy in the prawn's innate immune mechanisms.

Deciphering significances of autophagy in the development and metabolism of adipose tissue

The mechanisms of adipose tissue activation and inactivation have been a hot topic of research in the last decade, from which countermeasures have been attempted to be found against obesity as well as other lipid metabolism-related diseases, such as type 2 diabetes mellitus and non-alcoholic fatty liver disease. Autophagy has been shown to be closely related to the regulation of adipocyte activity, which is involved in the whole process including white adipocyte differentiation/maturation and brown or beige adipocyte generation/activation. Dysregulation of autophagy in adipose tissue has been demonstrated to be associated with obesity. On this basis, we summarize the pathways and mechanisms of autophagy involved in the regulation of lipid metabolism and present a review of its pathophysiological roles in lipid metabolism-related diseases, in the hope of providing ideas for the treatment of these diseases.

Quantitation of human mitochondrial DNA and whole mtGenomes sequencing of fingernail/hair shaft samples

The analysis of mitochondrial DNA (mtDNA) is suitable for fingernail/hair shaft samples in forensic science. A successful mtDNA forensic analysis depends on the quantity and quality of the mtDNA. The application of massively parallel sequence techniques to the analysis of mtDNA has the potential to improve the recovery of genetic information from difficult forensic specimens and to increase the discrimination potential of mtDNA by capturing and comparing full mtGenomes. In this study, we constructed mtDNA-specific standard curves using real-time PCR. The 105-base pair target sequence facilitates the amplification of degraded DNA and is minimally homologous to non-human mtDNA. The results indicated that the assay enables the absolute quantification of down to 10 copies of mtDNA and provides a dynamic range of eight orders of magnitude. Whole mtGenome sequencing experiments demonstrated that as few as 2 000 mtDNA copies resulted in a successful full region amplification and sequencing. Moreover, the frequency of point heteroplasmy from one donor showed that hairs from the same donor have been found to differ within and among themselves and from other tissues, which could impact the interpretation of the results obtained in a forensic investigation.

DNA damage response regulator ATR licenses PINK1-mediated mitophagy

Defective DNA damage response (DDR) and mitochondrial dysfunction are a major etiology of tissue impairment and aging. Mitochondrial autophagy (mitophagy) is a mitochondrial quality control (MQC) mechanism to selectively eliminate dysfunctional mitochondria. ATR (ataxia-telangiectasia and Rad3-related) is a key DDR regulator playing a pivotal role in DNA replication stress response and genomic stability. Paradoxically, the human Seckel syndrome caused by ATR mutations exhibits premature aging and neuropathies, suggesting a role of ATR in nonreplicating tissues. Here, we report a previously unknown yet direct role of ATR at mitochondria. We find that ATR and PINK1 (PTEN-induced kinase 1) dock at the mitochondrial translocase TOM/TIM complex, where ATR interacts directly with and thereby stabilizes PINK1. ATR deletion silences mitophagy initiation thereby altering oxidative phosphorylation functionality resulting in reactive oxygen species overproduction that attack cytosolic macromolecules, in both cells and brain tissues, prior to nuclear DNA. This study discloses ATR as an integrated component of the PINK1-mediated MQC program to ensure mitochondrial fitness. Together with its DDR function, ATR safeguards mitochondrial and genomic integrity under physiological and genotoxic conditions.

Mitogenome of Uncaria rhynchophylla: genome structure, characterization, and phylogenetic relationships

BACKGROUND

Uncaria rhynchophylla is listed in the Chinese pharmacopoeia as one of the five botanical sources of the traditional medicine Gou-Teng, which has been utilized for the treatment of mental and cardiovascular disorders. This particular species is well-known in China for its hook-like structures originating from the leaf axils. Despite available reports on its chloroplast genome, there persists a notable lack of understanding concerning the structural variations and evolution of its mitochondrial genome. This knowledge gap hinders our ability to fully comprehend its genetic attributes.

RESULTS

We successfully assembled the mitochondrial genome of U. rhynchophylla by seamlessly integrating Illumina short reads with Nanopore long reads, resulting in a non-circular genome comprising 1 circular contig and 2 linear contigs. The total length of this genome is 421,660 bp, encompassing 36 PCGs. The identification of 4 distinct pairs of repeats has unveiled their pivotal role in repeat-mediated recombination. Of the 28 homologous fragments derived from chloroplasts, the majority were observed to have been transferred from the inverted repeat (IR) regions of the chloroplast genome to the mitochondrial genome. The mitochondrial DNA provides a distinctive resolution for the positioning of several species within the Gentianales phylogenetic framework, which remains unresolved by chloroplast DNA.

CONCLUSION

By utilizing a newly assembled, high-quality mitochondrial genome of U. rhynchophylla, we have elucidated its intricate genomic structure, distinctive sequence characteristics, and potential for phylogenetic analysis. These findings mark significant strides in advancing our comprehension of the genetics of Uncaria.

Anti-Cancer and Pro-Immune Effects of Lauric Acid on Colorectal Cancer Cells

Lauric acid (LAA) is a 12-carbon medium-chain fatty acid that reportedly has antitumor and muscle-protecting effects. However, the details of these antitumor effects remain unclear. Therefore, in this study, we investigated the mechanism underlying the antitumor effects of LAA in CT26 and HT29 colorectal cancer (CRC) cell lines. Our in vitro findings demonstrated that LAA suppressed CRC cell proliferation, induced mitochondrial oxidative stress (reactive oxygen species (ROS)), inhibited oxidative phosphorylation (OXPHOS), and induced apoptosis. Moreover, in vivo analysis of LAA showed a more pronounced antitumor effect in CT26 cells in a syngeneic mouse tumor model than in vitro; therefore, we further investigated its impact on host antitumor immunity. We observed that LAA increased the number of effector T cells in mouse tumors, while in vitro LAA activated mouse splenocytes (SplC) and promoted OXPHOS. In two-dimensional co-culture of SplC and CT26 cells, LAA induced cell death in cancer cells. In three-dimensional co-culture, LAA promoted SplC infiltration and suppressed the formation of tumor spheres. Thus, LAA may exert antitumor effects through increased ROS production in cancer cells and effector T cell activation via increased energy metabolism. These results suggest that LAA, when used in combination with existing anti-cancer drugs, is likely to exhibit sensitizing effects in terms of both antitumor and antitumor immune effects, and future clinical studies are anticipated.

The POLG Variant c.678G>C; p.(Gln226His) Is Associated with Mitochondrial Abnormalities in Fibroblasts Derived from a Patient Compared to a First-Degree Relative

BACKGROUND

The nuclear-encoded enzyme polymerase gamma (Pol-γ) is crucial in the replication of the mitochondrial genome (mtDNA), which in turn is vital for mitochondria and hence numerous metabolic processes and energy production in eukaryotic cells. Variants in the POLG gene, which encodes the catalytic subunit of Pol-γ, can significantly impair Pol-γ enzyme function. Pol-γ-associated disorders are referred to as POLG-spectrum disorders (POLG-SDs) and are mainly autosomal-recessively inherited. Clinical manifestations include muscle weakness and fatigue, and severe forms of the disease can lead to premature death in infancy, childhood, and early adulthood, often associated with seizures, liver failure, or intractable epilepsy. Here, we analyzed fibroblasts from a compound heterozygous patient with the established pathogenic variant c.2419C>T; p.(Arg807Cys) and a previously undescribed variant c.678G>C; p.(Gln226His) with a clinical manifestation compatible with POLG-SDs, sensory ataxic neuropathy, and infantile muscular atrophy. We conducted a battery of functional studies for Pol-γ and mitochondrial dysfunction on the patient's fibroblasts, to test whether the novel variant c.678G>C; p.(Gln226His) may be causative in human disease.

AIMS/METHODS

We analyzed skin-derived fibroblasts in comparison to a first-degree relative (the mother of the patient), an asymptomatic carrier harboring only the established c.2419C>T; p.(Arg807Cys) mutation. Assessments of mitochondrial function included measurements of mtDNA content, mRNA levels of mitochondrial genes, mitochondrial mass, and mitochondrial morphology.

CASE PRESENTATION AND RESULTS

A 13-year-old male presented with symptoms starting at three years of age, including muscle weakness and atrophy in the lower extremities and facial muscles, which later extended to the upper limbs, voice, and back muscles, without further progression. The patient also reported fatigue and muscle pain after physical activity, with no sensory deficits. Extensive diagnostic tests such as electromyography, nerve conduction studies, muscle biopsy, and MRI were unremarkable. Exome sequencing revealed that he carried the compound heterozygous variants in POLG c.678G>C; p.(Gln226His) and c.2419C>T; p.(Arg807Cys), but no other potential genetic pathogenic causes. In comparison to a first-degree relative (his mother) who only carried the c.2419C>T; p.(Arg807Cys) pathogenic mutation, in vitro analyses revealed a significant reduction in mtDNA content (~50%) and mRNA levels of mtDNA-encoded proteins. Mitochondrial mass was reduced by approximately 20%, and mitochondrial interconnectivity within cells was impaired, as determined by fluorescence microscopy and mitochondrial staining.

CONCLUSIONS

Our findings suggest that the c.678G>C; p.(Gln226His) variant, in conjunction with the c.2419C>T; p.(Arg807Cys) mutation, may compromise mtDNA replication and mitochondrial function and could result in clinically significant mitochondriopathy. As this study is based on one patient compared to a first-degree relative (but with an identical mitochondrial genome), the pathogenicity of c.678G>C; p.(Gln226His) of POLG should be confirmed in future studies, in particular, in conjunction with other POLG-variants.

Celastrol ameliorates lipopolysaccharide (LPS)-induced acute lung injury by improving mitochondrial function through AMPK/PGC-1α/Nrf1-dependent mechanism

Acute lung injury (ALI) is a devastating clinical syndrome without effective therapy. Celastrol, as a natural anti-inflammatory compound, has showed therapeutic potential against inflammatory diseases. In this study, we have investigated the potential effect of Celastrol on lipopolysaccharide (LPS)-induced ALI. C57BL/6J mice, Nrf1-knockout mice and A549 (human alveolar epithelial cell line) cells were used to investigate the protective role of Celastrol in LPS-induced ALI. Our data showed that administration of Celastrol significantly alleviated lung pathologic injury and increased the survival rate, which was associated with the improvement of mitochondrial function in the injured lung. Moreover, Celastrol enhanced phosphorylation of AMP-activated protein kinase (AMPK) and expression of peroxisome proliferator-activated receptor coactivator protein-1α (PGC-1α), thereby increasing the nuclear translocation of nuclear respiratory factor 1 (Nrf1) and subsequent up-regulation of its downstream mitochondria electron transport chain complex I (NDUF) gene expression, which induced an increase in mitochondrial complex Ⅰ activity. The beneficial effects of Celastrol on regulation of Nrf1 were abolished by inhibition of AMPK and PGC-1α. Finally, in Nrf1 deficient mice, the protective effects of Celastrol on LPS-induced ALI were largely vanished. Our data indicated that Celastrol can prevent LPS-induced ALI by improving mitochondrial function through AMPK/PGC-1α/Nrf1-dependent mechanism, suggesting that Celastrol may represent a novel therapeutic potential for LPS-induced ALI.

Mitochondria at the crossroad of dysregulated inflammatory and metabolic processes in bipolar disorders

In last few decades, considerable evidence has emphasized the significant involvement of mitochondria, often referred to as the "powerhouse of the cell," in the pathophysiology of bipolar disorder (BD). Given crucial mitochondrial functions in cellular metabolism and inflammation, both of which are compromised in BD, this perspective review examines the central role of mitochondria in inflammation and metabolism within the context of this disorder. We first describe the significance of mitochondria in metabolism before presenting the dysregulated inflammatory and metabolic processes. Then, we present a synthetic and hypothetical model of the importance of mitochondria in those dysfunctional pathways. The article also reviews different techniques for assessing mitochondrial function and discuss diagnostic and therapeutic implications. This review aims to improve the understanding of the inflammatory and metabolic comorbidities associated with bipolar disorders along with mitochondrial alterations within this context.

Research progress of mitochondrial dysfunction induced pyroptosis in acute lung injury

Acute lung injury (ALI) is a common critical respiratory disease in clinical practice, especially in the ICU, with a high mortality rate. The pathogenesis of ALI is relatively complex, mainly involving inflammatory response imbalance, oxidative stress, cell apoptosis, and other aspects. However, currently, the treatment measures taken based on the above mechanisms have not had significant effects. Recent research shows that mitochondrial dysfunction and pyroptosis play an important role in ALI, but there is not much analysis on the relationship between mitochondrial dysfunction and pyroptosis at present. This article reviews the situation of mitochondrial dysfunction in ALI, pyroptosis in ALI, whether mitochondrial dysfunction is related to pyroptosis in ALI, and how to do so, and further analyzes the relationship between them in ALI. This review describes how to alleviate mitochondrial dysfunction, and then suppress the associated immunological pyroptosis, providing new ideas for the clinical treatment of ALI.

Mitochondrial HKDC1 suppresses oxidative stress and apoptosis by regulating mitochondrial function in goose fatty liver

Different from human non-alcoholic fatty liver disease (NAFLD), goose fatty liver is physiological with no inflammation. Consistently, mitochondrial dysfunction, oxidative stress and apoptosis are rarely seen in goose fatty liver. Hexokinase domain-containing protein 1 (HKDC1) is involved in maintaining systemic glucose homeostasis, and its absence causes mitochondrial dysfunction. Here, we demonstrated that mitochondrial outer membrane-bound HKDC1 (mHKDC1) had an expression pattern different from that of whole-cell HKDC1 (wHKDC1). Data indicated that the protein level of whole-cell HKDC1 (wHKDC1) was increased but mHKDC1 was decreased in mouse fatty liver. Interestingly, both the protein levels of wHKDC1 and mHKDC1 were significantly increased in goose fatty liver. Treatment of goose or mouse hepatocytes with fatty liver-related factors could influence the expression of wHKDC1 and mHKDC1, but the influence on wHKDC1 was not identical to mHKDC1. HKDC1 overexpression in goose hepatocytes increased wHKDC1 and mHKDC1 expression, mitochondrial membrane potential (MMP), mitochondrial respiratory chain activity, and suppressed reactive oxygen species (ROS) generation, apoptosis and cytokine-cytokine receptor signaling pathway. In addition, mutations in mitochondrial signal peptide or activation domain of HKDC1 altered MMP or ROS levels. In conclusion, HKDC1, particularly mHKDC1, may protect goose fatty liver by regulating mitochondrial function, ROS generation, apoptosis, and inflammation-related pathways.

Mitochondrial Quality Control in Alzheimer's Disease: Insights from Caenorhabditis elegans Models

Alzheimer's disease (AD) is a complex neurodegenerative disorder that is classically defined by the extracellular deposition of senile plaques rich in amyloid-beta (Aβ) protein and the intracellular accumulation of neurofibrillary tangles (NFTs) that are rich in aberrantly modified tau protein. In addition to aggregative and proteostatic abnormalities, neurons affected by AD also frequently possess dysfunctional mitochondria and disrupted mitochondrial maintenance, such as the inability to eliminate damaged mitochondria via mitophagy. Decades have been spent interrogating the etiopathogenesis of AD, and contributions from model organism research have aided in developing a more fundamental understanding of molecular dysfunction caused by Aβ and toxic tau aggregates. The soil nematode C. elegans is a genetic model organism that has been widely used for interrogating neurodegenerative mechanisms including AD. In this review, we discuss the advantages and limitations of the many C. elegans AD models, with a special focus and discussion on how mitochondrial quality control pathways (namely mitophagy) may contribute to AD development. We also summarize evidence on how targeting mitophagy has been therapeutically beneficial in AD. Lastly, we delineate possible mechanisms that can work alone or in concert to ultimately lead to mitophagy impairment in neurons and may contribute to AD etiopathology.

Protein kinase 2 of the giant sarcomeric protein UNC-89 regulates mitochondrial morphology and function

UNC-89 is a giant sarcomeric M-line protein required for sarcomere organization and optimal muscle function. UNC-89 contains two protein kinase domains, PK1 and PK2, separated by an elastic region. Here we show that PK2 is a canonical kinase expected to be catalytically active. C. elegans expressing UNC-89 with a lysine to alanine (KtoA) mutation to inactivate PK2 have normally organized sarcomeres and SR, and normal muscle function. PK2 KtoA mutants have fragmented mitochondria, correlated with more mitochondrially-associated DRP-1. PK2 KtoA mutants have increased ATP levels, increased glycolysis and altered levels of electron transport chain complexes. Muscle mitochondria show increased complex I and decreased complex II basal respiration, each of which cannot be uncoupled. This suggests that mutant mitochondria are already uncoupled, possibly resulting from an increased level of the uncoupling protein, UCP-4. Our results suggest signaling from sarcomeres to mitochondria, to help match energy requirements with energy production.

CARM1 phosphorylation at S595 by p38γ MAPK drives ROS-mediated cellular senescence

CARM1 is predominantly localized in the nucleus and plays a pivotal role in maintaining mitochondrial homeostasis by regulating gene expression. It suppresses mitochondrial biogenesis by downregulating PGC-1α and TFAM expression, while promoting mitochondrial fission through increased DNM1L expression. Under oxidative stress, CARM1 translocates to the cytoplasm, where it directly methylates DRP1 and accelerates mitochondrial fission, enhancing reactive oxygen species (ROS) production. Cytoplasmic localization of CARM1 is facilitated by its phosphorylation at S595 by ROS-activated p38γ MAPK, creating a positive feedback loop. Consequently, cytoplasmic CARM1 contributes to cellular senescence by altering mitochondrial dynamics and increasing ROS levels. This observation was supported by the increased cytoplasmic CARM1 levels and disrupted mitochondrial dynamics in the transformed 10T1/2 cells. Moreover, CARM1 inhibitors not only inhibit the proliferation of cancer cells but also induce apoptotic death in senescent cells. These findings highlight the potential of CARM1 inhibitors, particularly those targeting cytoplasmic functions, as novel strategies for eliminating cancer and senescent cells.

Synthesis and anti-proliferative effect of novel 4-Aryl-1, 3-Thiazole-TPP conjugates via mitochondrial uncoupling process

With the advent of mitochondrial targeting moiety such as triphenlyphosphonium cation (TPP+), targeting mitochondria in cancer cells has become a promising strategy for combating tumors. Herein, a series of novel 4-aryl-1,3-thiazole derivatives linked to TPP+ moiety were designed and synthesized. The cytotoxicity against a panel of four cancer cell lines was evaluated by CCK-8 assay. Most of these compounds exhibited moderate to good inhibitory activity over HeLa, PC-3 and HCT-15 cells while MCF-7 cells were less sensitive to most compounds. Among them, compound 12a exhibited a significant anti-proliferative activity against HeLa cells, and prompted for further investigation. Specifically, 12a decreased mitochondrial membrane potential and enhanced levels of reactive oxygen species (ROS). The flow cytometry analysis revealed that compound 12a could induce apoptosis and cell cycle arrest at G0/G1 phase in HeLa cells. In addition, mitochondrial bioenergetics assay revealed that 12a displayed mild mitochondrial uncoupling effect. Taken together, these findings suggest the therapeutic potential of compound 12a as an antitumor agent targeting mitochondria.

Therapeutic Potential of Terpenoids in Cancer Treatment: Targeting Mitochondrial Pathways

BACKGROUND

In recent decades, natural compounds have been considered a significant source of new antitumor medicines due to their unique advantages. Several in vitro and in vivo studies have focused on the effect of terpenoids on apoptosis mediated by mitochondria in malignant cells.

RECENT FINDINGS

In this review article, we focused on six extensively studied terpenoids, including sesquiterpenes (dihydroartemisinin and parthenolide), diterpenes (oridonin and triptolide), and triterpenes (betulinic acid and oleanolic acid), and their efficacy in targeting mitochondria to induce cell death. Terpenoid-induced mitochondria-related cell death includes apoptosis, pyroptosis, necroptosis, ferroptosis, autophagy, and necrosis caused by mitochondrial permeability transition. Apoptosis and autophagy interact in meaningful ways. In addition, in view of several disadvantages of terpenoids, such as low stability and bioavailability, advances in research on combination chemotherapy and chemical modification were surveyed.

CONCLUSION

This article deepens our understanding of the association between terpenoids and mitochondrial cell death, presenting a hypothetical basis for the use of terpenoids in anticancer management.

The Mitochondrial Distribution and Morphology Family 33 Gene FgMDM33 Is Involved in Autophagy and Pathogenesis in Fusarium graminearum

The mitochondrial distribution and morphology family 33 gene (MDM33) regulates mitochondrial homeostasis by mediating the mitochondrial fission process in yeast. The wheat head blight Fusarium graminearum contains an FgMdm33 protein that is orthologous to Saccharomyces cerevisiae Mdm33, albeit its function remains unknown. We have reported here the roles of FgMdm33 in regulating fungal morphogenesis, mitochondrial morphology, autophagy, apoptosis, and fungal pathogenicity. The ΔFgmdm33 mutants generated through a homologous recombination strategy in this study exhibited defects in terms of mycelial growth, conidia production, and virulence. Hyphal cells lacking FgMDM33 displayed elongated mitochondria and a dispensable respiratory-deficient growth phenotype, indicating the possible involvement of FgMDM33 in mitochondrial fission. The ΔFgmdm33 mutants displayed a remarkable reduction in the proteolysis of GFP-FgAtg8, whereas the formation of autophagic bodies in the hyphal cells of mutants was recorded under the induction of mitophagy. In addition, the transcriptional expression of the apoptosis-inducing factor 1 gene (FgAIF1) was significantly upregulated in the ΔFgmdm33 mutants. Cumulatively, these results indicate that FgMDM33 is involved in mitochondrial fission, non-selective macroautophagy, and apoptosis and that it regulates fungal growth, conidiation, and pathogenicity of the head blight pathogen.

Severe Allergy as a Chronic Inflammatory Condition From a Systems Biology Perspective

Persistent and unresolved inflammation is a common underlying factor observed in several and seemingly unrelated human diseases, including cardiovascular and neurodegenerative diseases. Particularly, in atopic conditions, acute inflammatory responses such as those triggered by insect venom, food or drug allergies possess also a life-threatening potential. However, respiratory allergies predominantly exhibit late immune responses associated with chronic inflammation, that can eventually progress into a severe phenotype displaying similar features as those observed in other chronic inflammatory diseases, as is the case of uncontrolled severe asthma. This review aims to explore the different facets and systems involved in chronic allergic inflammation, including processes such as tissue remodelling and immune cell dysregulation, as well as genetic, metabolic and microbiota alterations, which are common to other inflammatory conditions. Our goal here was to deepen on the understanding of an entangled disease as is chronic allergic inflammation and expose potential avenues for the development of better diagnostic and intervention strategies.

7-amino carboxycoumarin 2 inhibits lactate induced epithelial-to-mesenchymal transition via MPC1 in oral and breast cancer cells

Lactate is an oncometabolite that play important role in tumor aggressiveness. Lactate from the tumor microenvironment (TME) is taken up by cancer cells as an energy resource via mitochondrial oxidative phosphorylation (or OXPHOS). In the present study, by using an online meta-analysis tool we demonstrated that in oral squamous cancer cells (OSCCs) glycolytic and OXPHOS governing genes are overexpressed, like in breast cancer. For experimental demonstration, we treated the OSCC cell line (SCC4) and breast cancer cells (MDA-MB-231) with sodium L-lactate and analyzed its effects on changes in EMT and migration. For the therapeutic intervention of lactate metabolism, we used AZD3965 (an MCT1 inhibitor), and 7ACC2 (an MPC inhibitor). Like breast cancer, oral cancer tissues showed increased transcripts of 12 genes that were previously shown to be associated with glycolysis and OXPHOS. We experimentally demonstrated that L-lactate treatment induced mesenchymal markers and migration of cancer cells, which was significantly neutralized by MPC inhibitor that is, 7ACC2. Such an effect on EMT status was not observed with AZD3965. Furthermore, we showed that lactate treatment increases the MPC1 expression in both cancer cells, and this might be the reason why cancer cells in the high lactate environment are more sensitive to 7ACC2. Overall, our present findings demonstrate that extracellular lactate positively regulates the MPC1 protein expression in cancer cells, thereby putting forward the notion of using 7ACC2 as a potential therapeutic alternative to inhibit malignant oxidative cancers. Future preclinical studies are warranted to validate the present findings.

FABP3 Induces Mitochondrial Autophagy to Promote Neuronal Cell Apoptosis in Brain Ischemia-Reperfusion Injury

This study elucidates the molecular mechanisms by which FABP3 regulates neuronal apoptosis via mitochondrial autophagy in the context of cerebral ischemia-reperfusion (I/R). Employing a transient mouse model of middle cerebral artery occlusion (MCAO) established using the filament method, brain tissue samples were procured from I/R mice. High-throughput transcriptome sequencing on the Illumina CN500 platform was performed to identify differentially expressed mRNAs. Critical genes were selected by intersecting I/R-related genes from the GeneCards database with the differentially expressed mRNAs. The in vivo mechanism was explored by infecting I/R mice with lentivirus. Brain tissue injury, infarct volume ratio in the ischemic penumbra, neurologic deficits, behavioral abilities, neuronal apoptosis, apoptotic factors, inflammatory factors, and lipid peroxidation markers were assessed using H&E staining, TTC staining, Longa scoring, rotation experiments, immunofluorescence staining, and Western blot. For in vitro validation, an OGD/R model was established using primary neuron cells. Cell viability, apoptosis rate, mitochondrial oxidative stress, morphology, autophagosome formation, membrane potential, LC3 protein levels, and colocalization of autophagosomes and mitochondria were evaluated using MTT assay, LDH release assay, flow cytometry, ROS/MDA/GSH-Px measurement, transmission electron microscopy, MitoTracker staining, JC-1 method, Western blot, and immunofluorescence staining. FABP3 was identified as a critical gene in I/R through integrated transcriptome sequencing and bioinformatics analysis. In vivo experiments revealed that FABP3 silencing mitigated brain tissue damage, reduced infarct volume ratio, improved neurologic deficits, restored behavioral abilities, and attenuated neuronal apoptosis, inflammation, and mitochondrial oxidative stress in I/R mice. In vitro experiments demonstrated that FABP3 silencing restored OGD/R cell viability, reduced neuronal apoptosis, and decreased mitochondrial oxidative stress. Moreover, FABP3 induced mitochondrial autophagy through ROS, which was inhibited by the free radical scavenger NAC. Blocking mitochondrial autophagy with sh-ATG5 lentivirus confirmed that FABP3 induces mitochondrial dysfunction and neuronal apoptosis by activating mitochondrial autophagy. In conclusion, FABP3 activates mitochondrial autophagy through ROS, leading to mitochondrial dysfunction and neuronal apoptosis, thereby promoting cerebral ischemia-reperfusion injury.

Exposure to 6-PPD quinone causes damage on mitochondrial complex I/II associated with lifespan reduction in Caenorhabditis elegans

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ) is an emerging pollutant transformed from 6-PPD. However, the effect of 6-PPDQ exposure on mitochondrion and underlying mechanism remains largely unclear. Using Caenorhabditis elegans as animal model, exposed to 6-PPDQ at 0.1-10 μg/L was performed form L1 larvae to adult day-1. Exposure to 6-PPDQ (1 and 10 μg/L) could increase oxygen consumption rate and decease adenosine 5'-triphosphate (ATP) content, suggesting induction of mitochondrial dysfunction. Activities of NADH dehydrogenase (complex I) and succinate dehydrogenase (complex II) were inhibited, accompanied by a decrease in expressions of gas-1, nuo-1, and mev-1. RNAi of gas-1 and mev-1 enhanced mitochondrial dysfunction and reduced lifespan of 6-PPDQ exposed nematodes. GAS-1 and MEV-1 functioned in parallel to regulate 6-PPDQ toxicity to reduce the lifespan. Insulin peptides and the insulin signaling pathway acted downstream of GAS-1 and MEV-1 to control the 6-PPDQ toxicity on longevity. Moreover, RNAi of sod-2 and sod-3, targeted genes of daf-16, caused susceptibility to 6-PPDQ toxicity in reducing lifespan and in causing reactive oxygen species (ROS) production. Therefore, 6-PPDQ at environmentally relevant concentrations (ERCs) potentially caused mitochondrial dysfunction by affecting mitochondrial complexes I and II, which was associated with lifespan reduction by affecting insulin signaling in organisms.

Astragaloside IV protects against autoimmune myasthenia gravis in rats via regulation of mitophagy and apoptosis

Astragaloside IV (AS‑IV) has various pharmacological effects, including antioxidant and immunoregulatory properties, which can improve myasthenia gravis (MG) symptoms. However, the potential mechanism underlying the effects of AS‑IV on MG remains to be elucidated. The present study aimed to investigate whether AS‑IV has a therapeutic effect on MG and its potential mechanism of action. By subcutaneously immunizing rats with R97‑116 peptide, an experimental autoimmune (EA) MG rat model was established. AS‑IV (40 or 80 mg/kg/day) treatment was then applied for 28 days after modeling. The results demonstrated that AS‑IV significantly ameliorated the weight loss, Lennon score and pathological changes in the gastrocnemius muscle of EAMG rats compared with the model group. Additionally, the levels of acetylcholine receptor antibody (AChR‑Ab) were significantly decreased, whereas mitochondrial function [ATPase and cytochrome c (Cyt‑C) oxidase activities] and ultrastructure were improved in the AS‑IV treated rats. Moreover, the mRNA and protein expression levels of phosphatase and tensin homolog‑induced putative kinase 1, Parkin, LC3II and Bcl‑2, key signaling molecules for mitophagy and apoptosis, were upregulated, whereas the mRNA and protein expression levels of p62, Cyt‑C, Bax, caspase 3 and caspase 9 were downregulated following AS‑IV intervention. In conclusion, AS‑IV may protect against EAMG in a rat model by modulating mitophagy and apoptosis. These findings indicated the potential mechanism underlying the effects of AS‑IV on MG and provided novel insights into treatment strategies for MG.

2,4,6-trinitrotoluene causes mitochondrial toxicity in Caenorhabditis elegans by affecting electron transport

As a typical energetic compound widely used in military activities, 2,4,6-trinitrotoluene (TNT) has attracted great attention in recent years due to its heavy pollution and wide distribution in and around the training facilities, firing ranges, and demolition sites. However, the subcellular targets and the underlying toxic mechanism of TNT remain largely unknown. In this study, we explored the toxic effects of TNT biological reduction on the mitochondrial function and homeostasis in Caenorhabditis elegans (C. elegans). With short-term exposure of L4 larvae, 10-1000 ng/mL TNT reduced mitochondrial membrane potential and adenosine triphosphate (ATP) content, which was associated with decreased expression of specific mitochondrial complex involving gas-1 and mev-1 genes. Using fluorescence-labeled transgenic nematodes, we found that fluorescence expression of sod-3 (muls84) and gst-4 (dvls19) was increased, suggesting that TNT disrupted the mitochondrial antioxidant defense system. Furthermore, 10 ng/mL TNT exposure increased the expression of the autophagy-related gene pink-1 and activated mitochondrial unfolded protein response (mt UPR), which was indicated by the increased expression of mitochondrial stress activated transcription factor atfs-1, ubiquitin-like protein ubl-5, and homeobox protein dve-1. Our findings demonstrated that TNT biological reduction caused mitochondrial dysfunction and the development of mt UPR protective stress responses, and provided a basis for determining the potential risks of energetic compounds to living organisms.

Mitochondrial Dysfunction and Fatigue in Sjögren's Disease

Objectives

Sjögren's disease (SjD) is a common exocrine disorder typified by chronic inflammation and dryness, but also profound fatigue, suggesting a pathological basis in cellular bioenergetics. In healthy states, damaged or dysfunctional mitochondrial components are broken down and recycled by mitophagy, a specialized form of autophagy. In many autoimmune disorders, however, evidence suggests that dysfunctional mitophagy allows poorly functioning mitochondria to persist and contribute to a cellular milieu with elevated reactive oxygen species. We hypothesized that mitophagic processes are dysregulated in SjD and that dysfunctional mitochondria contribute to overall fatigue. We sought to link fatigue with mitochondrial dysfunction directly in SjD, heretofore unexamined, and further sought to assess the pathogenic extent and implications of dysregulated mitophagy in SjD.

Methods

We isolated pan T cells via negative selection from the peripheral blood mononuclear cells of 17 SjD and 8 age-matched healthy subjects, all of whom completed fatigue questionnaires prior to phlebotomy. Isolated T cells were analyzed for mitochondrial oxygen consumption rate (OCR) and glycolysis using Seahorse, and linear correlations with fatigue measures were assessed. A mitophagy transcriptional signature in SjD was identified by reanalysis of whole-blood microarray data from 190 SjD and 32 healthy subjects. Differential expression analyses were performed by case/control and subgroup analyses comparing SjD patients by mitophagy transcriptional cluster against healthy subjects followed by bioinformatic interpretation using gene set enrichment analysis.

Results

Basal OCR, ATP-linked respiration, maximal respiration, and reserve capacity were significantly lower in SjD compared to healthy subjects with no observed differences in non-mitochondrial respiration, basal glycolysis, or glycolytic stress. SjD lymphocytic mitochondria show structural alterations compared to healthy subjects. Fatigue scores related to pain/discomfort in SjD correlated with the altered OCR. Results from subgroup analyses by mitophagic SjD clusters revealed highly variable inter-cluster differentially expressed genes (DEGs) and expanded the number of SjD-associated gene targets by tenfold within the same dataset.

Conclusion

Mitochondrial dysfunction, associated with fatigue, is a significant problem in SjD and warrants further investigation.

6PPD induced cardiac dysfunction in zebrafish associated with mitochondrial damage and inhibition of autophagy processes

The compound 6PPD is widely acknowledged for its antioxidative properties; however, concerns regarding its impact on aquatic organisms have spurred comprehensive investigations. In our study, we advanced our comprehension by revealing that exposure to 6PPD could induce cardiac dysfunction, myocardial injury and DNA damage in adult zebrafish. Furthermore, our exploration unveiled that the exposure of cardiomyocytes to 6PPD resulted in apoptosis and mitochondrial injury, as corroborated by analyses using transmission electron microscopy and flow cytometry. Significantly, our study demonstrated the activation of the autophagy pathway in both the heart of zebrafish and cardiomyocytes, as substantiated by transmission electron microscopy and immunofluorescent techniques. Importantly, the increased the expression of P62 in the heart and cardiomyocytes suggested an inhibition of the autophagic process. The reduction in autophagy flux was also verified through in vivo experiments involving the infection of mCherry-GFP-LC3. We further identified that the fusion of autophagosomes and lysosomes was impaired in the 6PPD treatment group. In summary, our findings indicated that the impaired fusion of autophagosomes and lysosomes hampered the autophagic degradation process, leading to apoptosis and ultimately resulting in cardiac dysfunction and myocardial injury. This study discovered the crucial role of the autophagy pathway in regulating 6PPD-induced cardiotoxicity. SYNOPSIS: 6PPD exposure inhibited the autophagic degradation process and induced mitochondrial injury and apoptosis in the heart of adult zebrafish.

Intermembrane space-localized TbTim15 is an essential subunit of the single mitochondrial inner membrane protein translocase of trypanosomes

All mitochondria import >95% of their proteins from the cytosol. This process is mediated by protein translocases in the mitochondrial membranes, whose subunits are generally highly conserved. Most eukaryotes have two inner membrane protein translocases (TIMs) that are specialized to import either presequence-containing or mitochondrial carrier proteins. In contrast, the parasitic protozoan Trypanosoma brucei has a single TIM complex consisting of one conserved and five unique subunits. Here, we identify candidates for new subunits of the TIM or the presequence translocase-associated motor (PAM) using a protein-protein interaction network of previously characterized TIM and PAM subunits. This analysis reveals that the trypanosomal TIM complex contains an additional trypanosomatid-specific subunit, designated TbTim15. TbTim15 is associated with the TIM complex, lacks transmembrane domains, and localizes to the intermembrane space. TbTim15 is essential for procyclic and bloodstream forms of trypanosomes. It contains two twin CX9C motifs and mediates import of both presequence-containing and mitochondrial carrier proteins. While the precise function of TbTim15 in mitochondrial protein import is unknown, our results are consistent with the notion that it may function as an import receptor for the non-canonical trypanosomal TIM complex.

Linking triphenylphosphonium cation to a bicyclic hydroquinone improves their antiplatelet effect via the regulation of mitochondrial function

Platelets are the critical target for preventing and treating pathological thrombus formation. However, despite current antiplatelet therapy, cardiovascular mortality remains high, and cardiovascular events continue in prescribed patients. In this study, first results were obtained with ortho-carbonyl hydroquinones as antiplatelet agents; we found that linking triphenylphosphonium cation to a bicyclic ortho-carbonyl hydroquinone moiety by a short alkyl chain significantly improved their antiplatelet effect by affecting the mitochondrial functioning. The mechanism of action involves uncoupling OXPHOS, which leads to an increase in mitochondrial ROS production and a decrease in the mitochondrial membrane potential and OCR. This alteration disrupts the energy production by mitochondrial function necessary for the platelet activation process. These effects are responsive to the complete structure of the compounds and not to isolated parts of the compounds tested. The results obtained in this research can be used as the basis for developing new antiplatelet agents that target mitochondria.

Lymphocyte antigen 96: A new potential biomarker and immune target in Parkinson's disease

BACKGROUND

Lymphocyte antigen 96 (LY96) plays an important role in innate immunity and has been reported to be associated with various neurological diseases. However, its role in Parkinson's disease (PD) remains unclear.

METHODS

Transcriptome data from a total of 49 patients with PD and 34 healthy controls were downloaded from the Gene Expression Omnibus (GEO) database to analyse the expression pattern of LY96 and its relationship with gene function and immune-related markers. In addition, peripheral blood samples were collected from clinical patients to validate LY96 mRNA expression levels. Finally, an in vitro cell model of PD based on highly differentiated SH-SY5Y cells was constructed, with small interfering RNA-silenced LY96 expression, and LY96 mRNA level, cell viability, flow cytometry, and mitochondrial membrane potential assays were performed.

RESULTS

The results of the analyses of the GEO database and clinical samples revealed significantly abnormally high LY96 expression in patients with PD compared with healthy controls. The results of cell experiments showed that inhibiting LY96 expression alleviated adverse cellular effects by increasing cell viability, reducing apoptosis, and reducing oxidative stress. Gene set enrichment analysis showed that LY96 was positively correlated with T1 helper cells, T2 helper cells, neutrophils, natural killer T cells, myeloid-derived suppressor cells, macrophages, and activated CD4 cells, and may participate in PD through natural killer cell-mediated cytotoxicity pathways and extracellular matrix receptor interaction pathways.

CONCLUSION

These findings suggested that LY96 might be a novel potential biomarker for PD, and offer insights into its immunoregulatory role.

Ferroptosis and hepatocellular carcinoma: the emerging role of lncRNAs

Hepatocellular carcinoma is the most common form of primary liver cancer and poses a significant challenge to the medical community because of its high mortality rate. In recent years, ferroptosis, a unique form of cell death, has garnered widespread attention. Ferroptosis, which is characterized by iron-dependent lipid peroxidation and mitochondrial alterations, is closely associated with the pathological processes of various diseases, including hepatocellular carcinoma. Long non-coding RNAs (lncRNAs), are a type of functional RNA, and play crucial regulatory roles in a variety of biological processes. In this manuscript, we review the regulatory roles of lncRNAs in the key aspects of ferroptosis, and summarize the research progress on ferroptosis-related lncRNAs in hepatocellular carcinoma.

PRR34-AS1 promotes mitochondrial division and glycolytic reprogramming in hepatocellular carcinoma cells through upregulation of MIEF2

LncRNA PRR34-AS1 overexpression promotes the proliferation and invasion of hepatocellular carcinoma (HCC) cells, but whether it affects HCC energy metabolism remains unclear. Mitochondrial division and glycolytic reprogramming play important roles in tumor development. In this study, the differential expression of PRR34-AS1 is explored via TCGA analysis, and higher levels of PRR34-AS1 are detected in patients with liver cancer than in healthy individuals. A series of experiments, such as CCK-8, PCR, and immunofluorescence staining, reveal that the proliferation, invasion, glycolysis, and mitochondrial division of PRR34-AS1-overexpressing hepatoma cells are significantly promoted. TCGA analysis and immunohistochemistry reveal high expression of the mitochondrial dynamin MIEF2 in liver cancer tissues. Dual-luciferase reporter assays confirm that miR-498 targets and binds to mitochondrial elongation factor 2 (MIEF2). In addition, we show that PRR34-AS1 can sponge miR-498. Therefore, we further investigate the effects of the lncRNA PRR34-AS1/miR-498/MIEF2 axis on the growth, glucose metabolism, and mitochondrial division in hepatocellular carcinoma cells. A series of experiments are performed on hepatocellular carcinoma cells after different treatments. The results show that the proliferative activity, invasive ability, and glycolytic level of hepatocellular carcinoma cells are decreased in HCC cells with low PRR34-AS1 expression, and the miR-498 expression level is increased in these cells. Inhibition of miR-498 or overexpression of MIEF2 restored the proliferative activity, invasive ability, glycolysis, and mitochondrial division in hepatocellular carcinoma cells. Thus, PRR34-AS1 regulates MIEF2 by sponging miR-498, thereby promoting mitochondrial division, mediating glycolytic reprogramming and ultimately driving the growth and invasion of HCC cells. Furthermore, in vivo mouse experiments yield results similar to those of the in vitro experiments, verifying the above results.

Redox signaling and skeletal muscle adaptation during aerobic exercise

Redox regulation is a fundamental physiological phenomenon related to oxygen-dependent metabolism, and skeletal muscle is mainly regarded as a primary site for oxidative phosphorylation. Several studies have revealed the importance of reactive oxygen and nitrogen species (RONS) in the signaling process relating to muscle adaptation during exercise. To date, improving knowledge of redox signaling in modulating exercise adaptation has been the subject of comprehensive work and scientific inquiry. The primary aim of this review is to elucidate the molecular and biochemical pathways aligned to RONS as activators of skeletal muscle adaptation and to further identify the interconnecting mechanisms controlling redox balance. We also discuss the RONS-mediated pathways during the muscle adaptive process, including mitochondrial biogenesis, muscle remodeling, vascular angiogenesis, neuron regeneration, and the role of exogenous antioxidants.

Mitochondrial Genomic Evidence of Selective Constraints in Small-Bodied Terrestrial Cetartiodactyla

Body size may drive the molecular evolution of mitochondrial genes in response to changes in energy requirements across species of different sizes. In this study, we perform selection pressure analysis and phylogenetic independent contrasts (PIC) to investigate the association between molecular evolution of mitochondrial genome protein-coding genes (mtDNA PCGs) and body size in terrestrial Cetartiodactyla. Employing selection pressure analysis, we observe that the average non-synonymous/synonymous substitution rate ratio (ω) of mtDNA PCGs is significantly reduced in small-bodied species relative to their medium and large counterparts. PIC analysis further confirms that ω values are positively correlated with body size (R2 = 0.162, p = 0.0016). Our results suggest that mtDNA PCGs of small-bodied species experience much stronger purifying selection as they need to maintain a heightened metabolic rate. On the other hand, larger-bodied species may face less stringent selective pressures on their mtDNA PCGs, potentially due to reduced relative energy expenditure per unit mass. Furthermore, we identify several genes that undergo positive selection, possibly linked to species adaptation to specific environments. Therefore, despite purifying selection being the predominant force in the evolution of mtDNA PCGs, positive selection can also occur during the process of adaptive evolution.

The Emerging Role of Microglial Hv1 as a Target for Immunomodulation in Myelin Repair

In the central nervous system (CNS), the myelin sheath ensures efficient interconnection between neurons and contributes to the regulation of the proper function of neuronal networks. The maintenance of myelin and the well-organized subtle process of myelin plasticity requires cooperation among myelin-forming cells, glial cells, and neural networks. The process of cooperation is fragile, and the balance is highly susceptible to disruption by microenvironment influences. Reactive microglia play a critical and complicated role in the demyelination and remyelination process. Recent studies have shown that the voltage-gated proton channel Hv1 is selectively expressed in microglia in CNS, which regulates intracellular pH and is involved in the production of reactive oxygen species, underlying multifaceted roles in maintaining microglia function. This paper begins by examining the molecular mechanisms of demyelination and emphasizes the crucial role of the microenvironment in demyelination. It focuses specifically on the role of Hv1 in myelin repair and its therapeutic potential in CNS demyelinating diseases.

Varespladib mitigates acute liver injury via suppression of excessive mitophagy on Naja atra envenomed mice by inhibiting PLA2

Snakebite envenomation often leads to severe visceral injuries, including acute liver injury (ALI). However, the toxicity mechanism remains unclear. Moreover, varespladib can directly inhibit phospholipase A2 (PLA2) in snake venom, but its protective effect on snakebite-induced ALI and the mechanism have not been clarified. Previous studies have shown that snake venom PLA2 leads to neuron cell death via reactive oxygen species (ROS), one of the initial factors related to the mitophagy pathway. The present study group also found that ROS accumulation occurred after Naja atra envenoming. Hematoxylin and eosin (H/E) staining and immunohistochemistry (IHC) were performed to identify the expression of inflammatory factors in the liver tissue, and flow cytometry and immunofluorescence were used to detect ROS levels and mitochondrial function. Immunofluorescence and western blotting were also used for detecting mitophagy pathway-related proteins. The results showed that N. atra bite induced ALI by activating mitophagy and inducing inflammation and that varespladib had a protective effect. Collectively, these results showed the pathological mechanism of ALI caused by N. atra bite and revealed the protective effect of varespladib.

Ceramides and mitochondrial homeostasis

Lipotoxicity arises from the accumulation of lipid intermediates in non-adipose tissue, precipitating cellular dysfunction and death. Ceramide, a toxic byproduct of excessive free fatty acids, has been widely recognized as a primary contributor to lipotoxicity, mediating various cellular processes such as apoptosis, differentiation, senescence, migration, and adhesion. As the hub of lipid metabolism, the excessive accumulation of ceramides inevitably imposes stress on the mitochondria, leading to the disruption of mitochondrial homeostasis, which is typified by adequate ATP production, regulated oxidative stress, an optimal quantity of mitochondria, and controlled mitochondrial quality. Consequently, this review aims to collate current knowledge and facts regarding the involvement of ceramides in mitochondrial energy metabolism and quality control, thereby providing insights for future research.

Nanoplastics Penetrate Human Bronchial Smooth Muscle and Small Airway Epithelial Cells and Affect Mitochondrial Metabolism

Micro- and nanoplastic particles, including common forms like polyethylene and polystyrene, have been identified as relevant pollutants, potentially causing health problems in living organisms. The mechanisms at the cellular level largely remain to be elucidated. This study aims to visualize nanoplastics in bronchial smooth muscle (BSMC) and small airway epithelial cells (SAEC), and to assess the impact on mitochondrial metabolism. Healthy and asthmatic human BSMC and SAEC in vitro cultures were stimulated with polystyrene nanoplastics (PS-NPs) of 25 or 50 nm size, for 1 or 24 h. Live cell, label-free imaging by holotomography microscopy and mitochondrial respiration and glycolysis assessment were performed. Furthermore, 25 and 50 nm NPs were shown to penetrate SAEC, along with healthy and diseased BSMC, and they impaired bioenergetics and induce mitochondrial dysfunction compared to cells not treated with NPs, including changes in oxygen consumption rate and extracellular acidification rate. NPs pose a serious threat to human health by penetrating airway tissues and cells, and affecting both oxidative and glycolytic metabolism.

Up-regulation of MIC19 promotes growth and metastasis of hepatocellular carcinoma by activating ROS/NF-κB signaling

BACKGROUND

Mitochondrial malfunction has been well-recognized as a critical step in the pathogenesis of many types of diseases, including cancer. MIC19 is a core a subunit of the MICOS complex that plays a critical role in maintaining the normal function of mitochondria. However, the biological functions of MIC19 in human hepatocellular carcinoma (HCC) remain unclear.

METHODS

The expression level of MIC19 in HCC was evaluated by bioinformatics analysis, quantitative real-time PCR and immunohistochemistry staining assays. Cell growth and metastasis experiments were used to assess the biological functions of MIC19 in HCC cells.

FINDINGS

MIC19 expression was frequently upregulated in both human HCC specimens and cell lines, and its upregulation is closely associated with patients' survival. Results from loss-of-function and gain-of-function experiments demonstrated that knockdown of MIC19 significantly attenuated, while overexpression of MIC19 enhanced, the proliferation, colony formation, migration and invasion abilities of HCC cells. Mechanistically, we found that MIC19 has no effect on mitochondrial energy production, while activated ROS/NF-κB signaling, which was required for MIC19-promoted HCC growth and metastasis.

INTERPRETATION

Our findings suggest that MIC19 play a critical oncogenic role in HCC, implying that MIC19 may serve as a potential therapeutic target in the treatment of HCC.

Effects of CuSO4 on hepatic mitochondrial function, biogenesis and dynamics in mice

Copper is an essential trace element for animal. Excessive intake of copper will cause a large accumulation of copper in the body, especially in the liver, and induce hepatotoxicity, however, there are few studies on the effects of copper on hepatic mitochondrial biogenesis and mitochondrial dynamics. In this study, mice were treated with different doses of CuSO4 (0, 10, 20, and 40 mg/kg) for 21 and 42 days by gavage. The results verified that CuSO4 decreased the content of mitochondrial respiratory chain complexes I-IV in mouse liver. CuSO4 treatment resulted the decrease in the protein and mRNA expression levels of PGC-1α, TFAM, and NRF1, which were the mitochondrial biogenesis regulator proteins. Meanwhile, the proteins involved in mitochondrial fusion were reduced by CuSO4 , such as Mfn1 and Mfn2, however, mitochondrial fission proteins Drip1 and Fis1 were significantly increased. Abovementioned results show that CuSO4 could induce mitochondria damage in the liver of mice, and mitochondrial biogenesis and mitochondrial dynamics are involved in the molecular mechanism of CuSO4 -induced hepatotoxicity.

Characterization and function of PTEN-induced putative kinase 1 (PINK1) in process of Zinc alleviates hepatic lipid deposition of yellow catfish (Pelteobagrus fulvidraco)

PTEN-induced putative kinase 1 (PINK1) is a key regulator of mitophagy, however, the relevant information remains poorly understood on aquatic animals. Here, a PINK1 gene was cloned, characterized and functionally studied in yellow catfish. PINK1 encoded a protein containing 570 amino acids, 2 functional domains. High fat (15.66%) fed fish showed a downregulation trend of liver PINK1 expression than that of normal fat (10.14%) group, and was reversed by the addition of Zn. In the in vitro study, high fat (HF) can increase lipid deposition and decrease by addition Zn (HFZ) in hepatocytes, whereas above phenomena reversed by overexpression/interference of PINK1, respectively. In addition, the addition of Zn can significantly affect mitochondrial activity, increase mitophagy, and improve the antioxidant activity of hepatocytes. Together, these findings illustrated that yellow catfish PINK1 is conserve, and it participated in mitochondria control of fish. These findings indicate Zn could alleviate high fat-induced hepatic lipid deposition of fish by activating PINK1-mediated mitophagy and provide basis for further exploring new approach for decreasing lipid deposition in fish products during aquaculture.