Emerging Roles of NDUFS8 Located in Mitochondrial Complex I in Different Diseases

Bioinformatics identification of shared signaling pathways and core targets linking Benzo[a]pyrene exposure to HCC progression

With the increasing prevalence of environmental pollutants, there is growing concern about the potential effects of these substances in major diseases such as liver cancer. Previous studies have suggested that various chemicals, such as benzo[a]pyrene(BaP), produced by burning carbon containing fuels, may negatively affect liver health, but the exact mechanisms remain unclear. This study aimed to explore the potential molecular mechanisms of BaP in the progression of liver cancer. Through an exhaustive study of databases such as ChEMBL, SwissTargetPrediction, STITCH and TCGA, we identified 169 potential targets that are closely related to BaP and liver cancer. Next, we conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses using the clusterProfiler package to study the biological functions and important pathways of potential targets induced by BaP, which showed that these targets were associated with mitochondrial function, cellular energy metabolism and REDOX reactions. The protein interaction (PPI) network was constructed using the STRING database and Cytoscape software to identify the core targets UBA52, NDUFS8, CYP1A2, NDUFS1 and CYP3A4. The interaction between BaP and these core proteins was further analyzed via molecular docking using the CB-Dock2 database, demonstrating high binding stability, which suggests their critical role in BaP-induced hepatocellular carcinoma (HCC) toxicity. Subsequently, we found significant differences in the expression of five core genes (UBA52, NDUFS8, CYP1A2, NDUFS1, CYP3A4) in HCC, and significant correlation between UBA52, NDUFS8 and CYP3A4 and survival of HCC patients. Single-cell sequencing analysis showed that the expression of UBA52 gene was particularly pronounced in the three immune cells.

NADH:ubiquinone oxidoreductase core subunit S8 expression and functional significance in non-small cell lung cancer

Hyperfunctional mitochondria provide a growth advantage by supporting the energy-intensive processes essential for non-small cell lung cancer (NSCLC). NADH:ubiquinone oxidoreductase core subunit S8 (NDUFS8) is a key subunit of mitochondrial complex I involved in oxidative phosphorylation (OXPHOS) and cellular energy production. Bioinformatics and local tissue examinations show that NDUFS8 expression is elevated in NSCLC compared to normal lung tissue. Both immortalized and primary human NSCLC cells exhibit higher NDUFS8 levels. Single-cell RNA sequencing confirmed NDUFS8 upregulation in cancerous cells of NSCLC tumor. Silencing NDUFS8 via shRNA or Cas9/sgRNA-mediated knockout (KO) disrupted mitochondrial functions, leading to decreased complex I activity, ATP depletion, mitochondrial depolarization, increased reactive oxygen species (ROS) production, and heightened lipid peroxidation. Furthermore, NDUFS8 silencing/KO triggered apoptosis and significantly reduced Akt-mTOR activation, cell viability, proliferation, and motility in various NSCLC cells. In contrast, ectopic overexpression of NDUFS8 boosted mitochondrial complex I activity and ATP levels, promoting Akt-mTOR activation, and enhancing NSCLC cell proliferation and motility. NDUFS8 also contributes to radioresistance in NSCLC; silencing or KO enhanced ionizing radiation (IR)-induced cytotoxicity, while overexpression mitigated it. Intratumoral injection of NDUFS8 shRNA-expressing adeno-associated virus significantly inhibited growth of primary NSCLC xenografts in nude mice, with observed NDUFS8 silencing, ATP reduction, oxidative damage, proliferation inhibition, Akt-mTOR inactivation and apoptosis in treated tissues. These findings highlight the pivotal pro-tumorigenic role of NDUFS8 in NSCLC.

NDUFS8-Related Leigh Syndrome Mimicking a Leukodystrophy

Leigh syndrome is a progressive infantile neurodegenerative disorder of mitochondrial metabolism that often leads to decompensation in the setting of metabolic stress. It is genetically heterogenous with varied inheritance patterns. One subtype includes NDUFS8-related autosomal recessive Leigh syndrome. This nuclear gene encodes a complex I subunit of the mitochondrial complex chain. Although Leigh syndrome is typically associated with basal ganglia and brainstem involvement, cases of confluent white matter disease have been described with NDUFS8-related disorders. We present the case of a 6-month-old girl with initial imaging suggestive of a leukodystrophy, later found to have a novel homozygous variant in NDUFS8. In conjunction with the clinical course, a diagnosis of Leigh syndrome was made. This case highlights that mitochondrial disorders should be considered on the differential for confluent cerebral white matter disease in early childhood.

Transcriptomic Analysis of Muscle Satellite Cell Regulation on Intramuscular Preadipocyte Differentiation in Tan Sheep

Intramuscular fat (IMF) content is a key factor influencing meat properties including tenderness, flavor, and marbling. However, the complex molecular mechanisms regulating IMF deposition, especially the interactions between intramuscular preadipocytes (IMAdCs) and skeletal muscle satellite cells (SMSCs), remain unclear. In this study, a direct co-culture system of sheep IMAdCs and SMSCs was used to elucidate their intercellular interactions. RNA sequencing and bioinformatics analyses were performed under monoculture and co-culture conditions for later stages of differentiation. The obtained results showed that SMSCs significantly inhibited the adipogenic capacity of IMAdCs. This was reflected in the co-culture markedly altered gene expression and observations of lipid droplets in our studies, i.e., the PPARG, ACOX2, PIK3R1, FABP5, FYN, ALDOC, PFKM, PFKL, HADH, and HADHB genes were down-regulated in the co-cultured IMAdCs in association with the inhibition of fat deposition, whereas ACSL3, ACSL4, ATF3, EGR1, and IGF1R within the genes upregulated in co-culture IMAdCs were associated with the promotion of lipid metabolism. In addition, GO, KEGG, and ligand-receptor pairing analyses further elucidated the molecular mechanisms of intercellular communication. These findings emphasize the regulatory role of SMSCs on intramuscular preadipocyte differentiation and lipid metabolism, providing a theoretical framework for targeted molecular strategies to improve sheep meat quality.

Leigh Syndrome: A Comprehensive Review of the Disease and Present and Future Treatments

Leigh syndrome (LS) is a severe neurodegenerative condition with an early onset, typically during early childhood or infancy. The disorder exhibits substantial clinical and genetic diversity. From a clinical standpoint, Leigh syndrome showcases a broad range of irregularities, ranging from severe neurological issues to minimal or no discernible abnormalities. The central nervous system is most affected, resulting in psychomotor retardation, seizures, nystagmus, ophthalmoparesis, optic atrophy, ataxia, dystonia, or respiratory failure. Some patients also experience involvement of the peripheral nervous system, such as polyneuropathy or myopathy, as well as non-neurological anomalies, such as diabetes, short stature, hypertrichosis, cardiomyopathy, anemia, renal failure, vomiting, or diarrhea (Leigh-like syndrome). Mutations associated with Leigh syndrome impact genes in both the mitochondrial and nuclear genomes. Presently, LS remains without a cure and shows limited response to various treatments, although certain case reports suggest potential improvement with supplements. Ongoing preclinical studies are actively exploring new treatment approaches. This review comprehensively outlines the genetic underpinnings of LS, its current treatment methods, and preclinical investigations, with a particular focus on treatment.

Comparative physiological, biochemical and transcriptomic analyses to reveal potential regulatory mechanisms in response to starvation stress in Cipangopaludina chinensis

Cipangopaludina chinensis, as a financially significant species in China, represents a gastropod in nature which frequently encounters starvation stress owing to its limited prey options. However, the underlying response mechanisms to combat starvation have not been investigated in depth. We collected C. chinensis under several times of starvation stress (0, 7, 30, and 60 days) for nutrient, biochemical characteristics and transcriptome analyses. The results showed that prolonged starvation stress (> 30 days) caused obvious fluctuations in the nutrient composition of snails, with dramatic reductions in body weight, survival and digestive enzyme activity (amylase, protease, and lipase), and markedly enhanced the antioxidant enzyme activities of the snails. Comparative transcriptome analyses revealed 3538 differentially expressed genes (DEGs), which were significantly associated with specific starvation stress-responsive pathways, including oxidative phosphorylation and alanine, aspartate, and glutamate metabolism. Then, we identified 40 candidate genes (e.g., HACD2, Cp1, CYP1A2, and GPX1) response to starvation stress through STEM and WGCNA analyses. RT-qPCR verified the accuracy and reliability of the high-throughput sequencing results. This study provides insights into snail overwintering survival and the potential regulatory mechanisms of snail adaptation to starvation stress.

Cellular signatures in human blood track bone mineral density in postmenopausal women

Osteoclasts are the sole bone-resorbing cells and are formed by the fusion of osteoclast precursor cells (OCPs) derived from myeloid lineage cells. Animal studies reveal that circulating OCPs (cOCPs) in blood travel to bone and fuse with bone-resident osteoclasts. However, the characteristics of human cOCPs and their association with bone diseases remain elusive. We have identified and characterized human cOCPs and found a positive association between cOCPs and osteoclast activity. Sorted cOCPs have a higher osteoclastogenic potential than other myeloid cells and effectively differentiate into osteoclasts. cOCPs exhibit distinct morphology and transcriptomic signatures. The frequency of cOCPs in the blood varies among treatment-naive postmenopausal women and has an inverse correlation with lumbar spine bone density and a positive correlation with serum CTX, a bone resorption marker. The increased cOCPs in treatment-naive patients with osteoporosis were significantly diminished by denosumab, a widely used antiresorptive therapy. Our study reveals the distinctive identity of human cOCPs and the potential link between the dynamic regulation of cOCPs and osteoporosis and its treatment. Taken together, our study enhances our understanding of human cOCPs and highlights a potential opportunity to measure cOCPs through a simple blood test, which could potentially identify high-risk individuals.

Revealing the potential role of hub metabolism-related genes and their correlation with immune cells in acute ischemic stroke

OBJECTIVES

Acute ischemic stroke (AIS) is caused by cerebral ischemia due to thrombosis in the blood vessel. The purpose of this study is to identify key genes related to metabolism to aid in the mechanism research and management of AIS.

MATERIALS AND METHODS

Gene expression data were downloaded from the Gene Expression Omnibus database. Weighted gene co-expression network analysis, Gene Ontology and kyoto encyclopedia of genes and genomes analysis were used to identify metabolism-related genes that may be involved in the regulation of AIS. A protein protein interaction network was mapped using Cytoscape based on the STRING database. Subsequently, hub metabolism-related genes were identified based on Cytoscape-CytoNCA and Cytoscape-MCODE plug-ins. Least absolute shrinkage and selection operator algorithm and differential expression analysis. In addition, drug prediction, molecular docking, ceRNA network construction, and correlation analysis with immune cell infiltration were performed to explore their potential molecular mechanisms of action in AIS. Finally, the expression of hub gene was verified by real-time PCR.

RESULTS

Metabolism-related genes FBL, HEATR1, HSPA8, MTMR4, NDUFC1, NDUFS8 and SNU13 were identified. The AUC values of FBL, HEATR1, HSPA8, MTMR4, NDUFS8 and SNU13 were all greater than 0.8, suggesting that they had good diagnostic accuracy. Correlation analysis found that their expression levels were also related to the infiltration levels of multiple immune cells, such as Activated.CD8.T.cell and Activated.dendritic.cell. It was found that only HSPA8 was successfully matched to drugs with literature support, and these drugs were acetaminophen, bupivacaine, dexamethasone, gentamicin, tretinoin and cisplatin. Moreover, it was also identified that the ENSG000000218510-hsa-miR-330-3p-HEATR1 axis may be involved in regulating AIS.

CONCLUSIONS

The identification of FBL, HEATR1, HSPA8, MTMR4, NDUFC1, NDUFS8 and SNU13 provides a new research direction for exploring the molecular mechanisms of AIS, which can help in clinical management and diagnosis.

The requirement of the mitochondrial protein NDUFS8 for angiogenesis

Mitochondria are important for the activation of endothelial cells and the process of angiogenesis. NDUFS8 (NADH:ubiquinone oxidoreductase core subunit S8) is a protein that plays a critical role in the function of mitochondrial Complex I. We aimed to investigate the potential involvement of NDUFS8 in angiogenesis. In human umbilical vein endothelial cells (HUVECs) and other endothelial cell types, we employed viral shRNA to silence NDUFS8 or employed the CRISPR/Cas9 method to knockout (KO) it, resulting in impaired mitochondrial functions in the endothelial cells, causing reduction in mitochondrial oxygen consumption and Complex I activity, decreased ATP production, mitochondrial depolarization, increased oxidative stress and reactive oxygen species (ROS) production, and enhanced lipid oxidation. Significantly, NDUFS8 silencing or KO hindered cell proliferation, migration, and capillary tube formation in cultured endothelial cells. In addition, there was a moderate increase in apoptosis within NDUFS8-depleted endothelial cells. Conversely, ectopic overexpression of NDUFS8 demonstrated a pro-angiogenic impact, enhancing cell proliferation, migration, and capillary tube formation in HUVECs and other endothelial cells. NDUFS8 is pivotal for Akt-mTOR cascade activation in endothelial cells. Depleting NDUFS8 inhibited Akt-mTOR activation, reversible with exogenous ATP in HUVECs. Conversely, NDUFS8 overexpression boosted Akt-mTOR activation. Furthermore, the inhibitory effects of NDUFS8 knockdown on cell proliferation, migration, and capillary tube formation were rescued by Akt re-activation via a constitutively-active Akt1. In vivo experiments using an endothelial-specific NDUFS8 shRNA adeno-associated virus (AAV), administered via intravitreous injection, revealed that endothelial knockdown of NDUFS8 inhibited retinal angiogenesis. ATP reduction, oxidative stress, and enhanced lipid oxidation were detected in mouse retinal tissues with endothelial knockdown of NDUFS8. Lastly, we observed an increase in NDUFS8 expression in retinal proliferative membrane tissues obtained from human patients with proliferative diabetic retinopathy. Our findings underscore the essential role of the mitochondrial protein NDUFS8 in regulating endothelial cell activation and angiogenesis.

Advancing In-Depth N-Terminomics Detection with a Cleavable 2-Pyridinecarboxyaldehyde Probe

Proteolysis, an irreversible post-translational modification catalyzed by proteases, plays a crucial role in various biological processes. Exploring abnormally hydrolyzed proteins in pathological tissues is a valuable approach for elucidating the mechanisms underlying disease development. Herein, we have developed a cleavable 2-pyridinecarboxyaldehyde probe (2PCA-Probe) that enables efficient and in-depth N-terminomics detection, addressing limitations of previous methods. Furthermore, we unexpectedly discovered a new marker capable of identifying N-terminal chemical labeling with the 2PCA-Probe and elucidated the reaction mechanism. Using this probe, we identified 4686 N-terminal peptides in colorectal cancer and adjacent tissues, significantly expanding the depth of the N-terminome and revealing the potential role of abnormal protein hydrolysis in colorectal cancer development.

Mitochondrial complex I subunit NDUFS8.2 modulates responses to stresses associated with reduced water availability

Mitochondria are important sources of energy in plants and are implicated in coordination of a number of metabolic and physiological processes including stabilization of redox balance, synthesis and turnover of a number of metabolites, and control of programmed cell death. Mitochondrial electron transport chain (mETC) is the backbone of the energy producing process which can influence other processes as well. Accumulating evidence suggests that mETC can affect responses to environmental stimuli and modulate tolerance to extreme conditions such as drought or salinity. Screening for stress responses of 13 Arabidopsis mitochondria-related T-DNA insertion mutants, we identified ndufs8.2-1 which has an increased ability to withstand osmotic and oxidative stresses compared to wild type plants. Insertion in ndufs8.2-1 disrupted the gene that encodes the NADH dehydrogenase [ubiquinone] fragment S subunit 8 (NDUFS8) a component of Complex I of mETC. ndufs8.2-1 tolerated reduced water availability, retained photosynthetic activity and recovered from severe water stress with higher efficiency compared to wild type plants. Several mitochondrial functions were altered in the mutant including oxygen consumption, ROS production, ATP and ADP content as well as activities of genes encoding alternative oxidase 1A (AOX1A) and various alternative NAD(P)H dehydrogenases (ND). Our results suggest that in the absence of NDUFS8.2 stress-induced ROS generation is restrained leading to reduced oxidative damage and improved tolerance to water deficiency. mETC components can be implicated in redox and energy homeostasis and modulate responses to stresses associated with reduced water availability.

Western diet-induced obesity results in brain mitochondrial dysfunction in female Ossabaw swine

Diet-induced obesity is implicated in the development of a variety of neurodegenerative disorders. Concurrently, the loss of mitochondrial Complex I protein or function is emerging as a key phenotype across an array of neurodegenerative disorders. Therefore, the objective of this study was to determine if Western diet (WD) feeding in swine [carbohydrate = 40.8% kCal (17.8% of total calories from high fructose corn syrup), protein = 16.2% kcal, fat = 42.9% kCal, and 2% cholesterol] would result in Complex I syndrome pathology. To characterize the effects of WD-induced obesity on brain mitochondria in swine, high resolution respirometry measurements from isolated brain mitochondria, oxidative phosphorylation Complex expression, and indices of oxidative stress and mitochondrial biogenesis were assessed in female Ossabaw swine fed a WD for 6-months. In line with Complex I syndrome, WD feeding severely reduced State 3 Complex I, State 3 Complex I and II, and uncoupled mitochondrial respiration in the hippocampus and prefrontal cortex (PFC). State 3 Complex I mitochondrial respiration in the PFC inversely correlated with serum total cholesterol. WD feeding also significantly reduced protein expression of oxidative phosphorylation Complexes I-V in the PFC. WD feeding significantly increased markers of antioxidant defense and mitochondrial biogenesis in the hippocampi and PFC. These data suggest WD-induced obesity may contribute to Complex I syndrome pathology by increasing oxidative stress, decreasing oxidative phosphorylation Complex protein expression, and reducing brain mitochondrial respiration. Furthermore, these findings provide mechanistic insight into the clinical link between obesity and mitochondrial Complex I related neurodegenerative disorders.

Dose- and Time-Dependent Effects of Radiofrequency Electromagnetic Field on Adipose Tissue: Implications of Thermoregulation and Mitochondrial Signaling

Recent studies have shed light on the effects of low-intensity radiofrequency (RF) fields on thermoregulation and adipose tissue metabolism. The present study aims to further explore these effects by analyzing the expression of thermoregulatory genes and investigating the involvement of mitochondria in adipose tissue metabolism. Male mice (n = 36 C57BL/6J) were assigned to either exposed or control groups. The exposed groups were subjected to RF fields at 900 MHz, with specific absorption rates (SAR) of 0.1 W/kg or 0.4 W/kg, either for three or seven consecutive days. The findings indicate that RF exposure leads to changes in adipose tissue markers, with some effects being dose-dependent and time-dependent. In brown adipose tissue (BAT), after 3 days of RF exposure, thermogenesis is reduced, mitochondrial activity in BAT decreases, and an increase in gene expression, responsible for balancing the regulatory and damaging effects of reactive oxygen species (ROS), was observed. This effect was partially compensated after 7 days of exposure. In white adipose tissue (WAT), RF exposure results in reduced fatty acid oxidation, impaired energy production, and hindered adipocyte differentiation. Notably, no effects of RF on mitochondrial biogenesis in WAT were observed. These findings contribute to understanding the effects of RF exposure on adipose tissue metabolism and thermoregulation, highlighting dose-dependent and time-dependent responses.