Ubiquinol-cytochrome C Reductase Core Protein 1 Research Articles

Deregulation of oxidative phosphorylation pathways in embryos derived in vitro from prepubertal and pubertal heifers based on whole-transcriptome sequencing

BackgroundAlthough, oocytes from prepubertal donors are known to be less developmentally competent than those from adult donors it does not restrain their ability to produce full-term pregnancies. The transcriptomic profile of embryos could be used as a predictor for embryo’s individual developmental competence. The aim of the study was to compare transcriptomic profile of blastocysts derived from prepubertal and pubertal heifers oocytes. Bovine cumulus-oocyte complexes (COCs) were obtained by ovum pick- up method from prepubertal and pubertal heifers. After in vitro maturation COCs were fertilized and cultured to the blastocyst stage. Total RNA was isolated from both groups of blastocysts and RNA-seq was performed. Gene ontology analysis was performed by DAVID (Database for Annotation, Visualization and Integrated Discovery).ResultsA higher average blastocyst rate was obtained in the pubertal than in the pre-pubertal group. There were no differences in the quality of blastocysts between the examined groups. We identified 436 differentially expressed genes (DEGs) between blastocysts derived from researched groups, of which 247 DEGs were downregulated in blastocysts derived from pubertal compared to prepubertal heifers oocytes, and 189 DEGs were upregulated. The genes involved in mitochondrial function, including oxidative phosphorylation (OXPHOS) were found to be different in studied groups using Kyoto Encyclopedia of Genes (KEGG) pathway analysis and 8 of those DEGs were upregulated and 1 was downregulated in blastocysts derived from pubertal compared to prepubertal heifers oocytes. DEGs associated with mitochondrial function were found: ATP synthases (ATP5MF-ATP synthase membrane subunit f, ATP5PD- ATP synthase peripheral stalk subunit d, ATP12A- ATPase H+/K + transporting non-gastric alpha2 subunit), NADH dehydrogenases (NDUFS3- NADH: ubiquinone oxidoreductase subunit core subunit S3, NDUFA13- NADH: ubiquinone oxidoreductase subunit A13, NDUFA3- NADH: ubiquinone oxidoreductase subunit A3), cytochrome c oxidase (COX17), cytochrome c somatic (CYCS) and ubiquinol cytochrome c reductase core protein 1 (UQCRC1). We found lower number of apoptotic cells in blastocysts derived from oocytes collected from prepubertal than those obtained from pubertal donors.ConclusionsDespite decreased expression of genes associated with OXPHOS pathway in blastocysts from prepubertal heifers oocytes, the increased level of ATP12A together with the lower number of apoptotic cells in these blastocysts might support their survival after transfer.

Formoterol Acting via β2-Adrenoreceptor Restores Mitochondrial Dysfunction Caused by Parkinson's Disease-Related UQCRC1 Mutation and Improves Mitochondrial Homeostasis Including Dynamic and Transport.

Formoterol, a β2-adrenergic receptor (β2AR) agonist, shows promise in various diseases, but its effectiveness in Parkinson's disease (PD) is debated, with unclear regulation of mitochondrial homeostasis. This study employed a cell model featuring mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) variants associated with familial parkinsonism, demonstrating mitochondrial dysfunction and dynamic imbalance, exploring the therapeutic effects and underlying mechanisms of formoterol. Results revealed that 24-h formoterol treatment enhanced cell proliferation, viability, and neuroprotection against oxidative stress. Mitochondrial function, encompassing DNA copy number, repatriation, and complex III-linked respiration, was comprehensively restored, along with the dynamic rebalance of fusion/fission events. Formoterol reduced extensive hypertubulation, in contrast to mitophagy, by significantly upregulating protein Drp-1, in contrast to fusion protein Mfn2, mitophagy-related protein Parkin. The upstream mechanism involved the restoration of ERK signaling and the inhibition of Akt overactivity, contingent on the activation of β2-adrenergic receptors. Formoterol additionally aided in segregating healthy mitochondria for distribution and transport, therefore normalizing mitochondrial arrangement in mutant cells. This study provides preliminary evidence that formoterol offers neuroprotection, acting as a mitochondrial dynamic balance regulator, making it a promising therapeutic candidate for PD.

Rare variant analysis of UQCRC1 in Chinese patients with early-onset Parkinson’s disease

Mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) gene has been identified as a causative gene for autosomal dominant Parkinson’s disease (PD), with the p.Y314S variant potentially associated with polyneuropathy in PD patients. The objectives of our study were to screen for UQCRC1 variants in Chinese patients with early-onset PD (EOPD) and explore the role of UQCRC1 in EOPD. We investigated the rare variants in 913 EOPD patients in our cohort using whole-exome sequencing, assessing their link to PD at both allele and gene levels. A total of 7 rare variants (minor allele frequency < 0.1%) of UQCRC1 were identified. However, no excessive burden of rare UQCRC1 variants was suggested in the EOPD patients. Further analysis with larger sample size and diverse regions is needed to determine the role of UQCRC1 in PD.

Novel pathogenic UQCRC2 variants in a female with normal neurodevelopment.

Electron transport chain (ETC) disorders are a group of rare, multisystem diseases caused by impaired oxidative phosphorylation and energy production. Deficiencies in complex III (CIII), also known as ubiquinol-cytochrome c reductase, are particularly rare in humans. Ubiquinol-cytochrome c reductase core protein 2 (UQCRC2) encodes a subunit of CIII that plays a crucial role in dimerization. Several pathogenic UQCRC2 variants have been identified in patients presenting with metabolic abnormalities that include lactic acidosis, hyperammonemia, hypoglycemia, and organic aciduria. Almost all previously reported UQCRC2-deficient patients exhibited neurodevelopmental involvement, including developmental delays and structural brain anomalies. Here, we describe a girl who presented at 3 yr of age with lactic acidosis, hyperammonemia, and hypoglycemia but has not shown any evidence of neurodevelopmental dysfunction by age 15. Whole-exome sequencing revealed compound heterozygosity for two novel variants in UQCRC2: c.1189G>A; p.Gly397Arg and c.437T>C; p.Phe146Ser. Here, we discuss the patient's clinical presentation and the likely pathogenicity of these two missense variants.

UQCRC1 variants in early-onset and familial Parkinson's disease in a Taiwanese cohort.

A recent Taiwanese study reported variants of the ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) gene linked to autosomal dominant parkinsonism with polyneuropathy. This study investigated the pathogenicity of UQCRC1 in a Taiwanese cohort of patients with Parkinson's disease (PD). This study involved 107 participants (98 with early-onset PD and nine with familial PD). All UQCRC1 coding exons and exon-intron boundaries were sequenced. The rarity and pathogenicity of the identified variants were analyzed. The carrier frequencies of our cohort and the Taiwan Biobank were compared through a Pearson's χ2 or Fisher's exact test along with Bonferroni corrections. Three missense variants (c.643G > C, p.D215H; c.800C > G, p.P267R, and c.923A > G, p.N308S) and seven rare variants were identified. No significant differences in the missense-variant carrier frequency were noted between our cohort and individuals in the Taiwan Biobank. Furthermore, no significant associations were noted between the variants and the risk of PD. Our study is not supporting a role of UQCRC1 variants in PD.

Long non-coding RNA LINC01133 regulates cementogenic differentiation of human periodontal ligament stem cells by modulating mitochondrial functions

Objective: To investigate the effects of long non-coding RNA (lncRNA) LINC01133 on the cementogenic differentiation of human periodontal ligament stem cells (hPDLSC) and the underlying mechanism. Methods: A total of 12 teeth were harvested from 10 patients aged 17-30 years in the Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University for impacted or orthodontic reasons from September 2021 to January 2022. The hPDLSCs were isolated from the teeth and transfected with small interfering RNA-LINC01133 (si-LINC01133) or small interfering RNA-negative control (si-NC). The si-LINC01133 was regarded as the experimental group, and the si-NC was regarded as the control one. The silencing efficiency of LINC01133 in the hPDLSCs was evaluated by real-time quantitative PCR (RT-qPCR). Western blotting was used to detect the protein expression levels of cementogenic differentiation-related factors including bone sialoprotein (BSP), cementum attachment protein (CAP), and cementum protein-1 (CEMP-1). Mitochondrial reactive oxygen species (mtROS) production was assessed using the MitoSox by flow cytometry. Mitochondrial membrane potential (MMP) was detected by JC-1 fluorescence staining. Mitochondrial respiratory chain complexes proteins including NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 8 (NDUFB8), succinate dehydrogenase complex flavoprotein subunit A (SDHA), ubiquinol-cytochrome c reductase core protein 1 (UQCR1), cytochrome c oxidase subunit 4 isoform 1 (COXⅣ), and ATP synthase F1 subunit alpha (ATP5A) were evaluated by Western blotting. Results: The expression levels of LINC01133 could be suppressed by more than 60% with si-LINC01133 (control group: 1.000±0.000, experimental group: 0.385±0.128) (t=10.72, P<0.01). Suppression of LINC01133 in hPDLSCs decreased the levels of cementogenic differentiation-related proteins including BSP (control group: 1.000±0.000, experimental group: 0.664±0.179) (t=4.62, P<0.01) and CAP (control group: 1.000±0.000, experimental group: 0.736±0.229) (t=2.83, P<0.05). Suppression of LINC01133 in hPDLSCs increased the production of mtROS (control group: 1.000±0.000, experimental group: 1.458±0.185) (t=4.96, P<0.05) and the expression of NDUFB8 (control group: 1.000±0.000, experimental group: 1.683±0.397) (t=3.45, P<0.05), as well as decreased MMP levels (control group: 1.000±0.000, experimental group: 0.209±0.029) (t=53.99, P<0.01) and the expression of SDHA (control group: 1.000±0.000, experimental group: 0.428±0.228) (t=5.02, P<0.05). No significant changes in the UQCR1, COXⅣ, and ATP5A expression levels were found between the control group and exprimental group (P>0.05). Conclusions: LINC01133 regulates the cementogenic differentiation of hPDLSCs possibly via modulating the mitochondrial functions.

Activation of UQCRC2-dependent mitophagy by tetramethylpyrazine inhibits MLKL-mediated hepatocyte necroptosis in alcoholic liver disease

Hepatocyte necroptosis is a core pathogenetic event during alcoholic liver disease. This study was aimed to explore the potential of tetramethylpyrazine (TMP), an active hepatoprotective ingredient extracted from Ligusticum Wallichii Franch, in limiting alcohol-triggered hepatocyte necroptosis and further specify the molecular mechanism. Results revealed that TMP reduced activation of receptor-interacting protein kinase 1 (RIPK1)/RIPK3 necrosome in ethanol-exposed hepatocytes and phosphorylation of mixed-lineage kinase domain-like protein (MLKL), which thereby diminished necroptosis and leakage of damage-associated molecular patterns. Suppression on mitochondrial translocation of p-MLKL by TMP contributed to recovery of mitochondrial function in ethanol-damaged hepatocytes. TMP also disrupted necroptotic signal loop by interrupting mitochondrial reactive oxygen species (ROS)-dependent positive feedback between p-MLKL and RIPK1/RIPK3 necrosome. Further, TMP promoted clearance of impaired mitochondria in ethanol-incubated hepatocytes via restoring PINK1/parkin-mediated mitophagy. Ubiquinol-cytochrome c reductase core protein 2 (UQCRC2) was downregulated in ethanol-exposed hepatocytes, which was restored after TMP treatment. In vitro UQCRC2 knockdown lowered the capacities of TMP in reducing mitochondrial ROS accumulation, relieving mitochondria damage, and enhancing PINK1/parkin-mediated mitophagy in ethanol-exposed hepatocytes. Analogously, systematic UQCRC2 knockdown interrupted the actions of TMP to trigger autophagic signal, repress necroptotic signal, and protect against alcoholic liver injury, inflammation, and ROS overproduction. In conclusion, this work concluded that TMP rescued UQCRC2 expression in ethanol-challenged hepatocytes, which contributed to necroptosis inhibition by facilitating PINK1/parkin-mediated mitophagy. These findings uncovered a potential molecular pharmacological mechanism underlying the hepatoprotective action of TMP and suggested TMP as a promising therapeutic candidate for alcoholic liver disease.

Ubiquinol-cytochrome c reductase core protein 1 contributes to cardiac tolerance to acute exhaustive exercise.

Ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) is an indispensable component of mitochondrial complex III. It plays a key role in cardioprotection and maintaining mitochondrion function. However, the exact role of UQCRC1 in maintaining cardiac function has not been reported by in vivo models. Also, the exact biological functions of UQCRC1 are far from fully understood. UQCRC1+/- mice had decreased both mRNA and protein expression of UQCRC1 in the left ventricular myocardia, and these mice had reduced tolerance to acute exhaustive exercise including decreased time and distance with higher apoptosis rate, higher expression level of cleaved CASPASE 3, and higher ratio of cleaved PARP1 to full-length PARP1. Moreover, UQCRC1 knockdown led to increased LV interventricular septal thicknesses both at systole and diastole, as well as decreased LV volume both at end-systole and end-diastole. Finally, UQCRC1 gene disruption resulted in mitochondrial vacuolation, fibril disarrangement, and more severe morphological and structural changes in mitochondria after acute exhaustive exercise. In conclusion, UQCRC1 contributes to cardiac tolerance to acute exhaustive exercise in mice, and it may be an essential component of complex III, playing a crucial role in maintaining cardiac functions.

AMPK protects against alcohol-induced liver injury through UQCRC2 to up-regulate mitophagy

ABSTRACT Recent reports indicated that mitophagy protects against alcohol-induced liver injury, which helps remove damaged mitochondria to reduce the accumulation of reactive oxygen species (ROS). AMP-activated protein kinase (AMPK) has been recently used in ALD (alcoholic liver disease) and mitochondrial dysfunction research. However, the inner mechanism, whether AMPK can regulate mitophagy in ALD, remains unknown. Here we found that AMPK can significantly reduce alcohol-induced liver injury and enhances hepatocytes’ mitophagy level. Next, we identified that AMPK rescued alcohol-induced low expression of UQCRC2 (ubiquinol-cytochrome c reductase core protein 2). Interestingly, UQCRC2 knockdown (KD) treatment causes impaired mitophagy, whereas UQCRC2 overexpression (OE) can significantly increase mitophagy to attenuate liver injury. Also, we identified that AMPK indirectly upregulates UQCRC2 protein level, and RNA-seq, chromatin immunoprecipitation (ChIP) assay, bioinformatics, and luciferase assays helped us understand that AMPK enhanced UQCRC2 gene transcription through activating NFE2L2/NRF2 (nuclear factor, erythroid 2 like 2). Our results demonstrate that AMPK regulating UQCRC2 is a significant mitochondrial event in mitophagy. It identifies a new signaling axis, AMPK-NFE2L2-UQCRC2, in the regulation of mitophagy levels in the liver, suggesting a possible therapeutic strategy to treat ALD. Abbreviations: AAV: AENO-associated virus; ALD: alcoholic liver disease; AMPK: AMP-activated protein kinase; BUN: blood urea nitrogen; H&E: hematoxylin and eosin; CCCP: carbonyl cyanide 3-chlorophenylhydrazone; ChIP: chromatin immunoprecipitation assay; CO-IP: co-immunoprecipitation; COPD: chronic obstructive pulmonary disease; EM: electron microscope; GOT1/AST: glutamic-oxaloacetic transaminase 1; GPT/ALT: glutamic—pyruvic transaminase; IF: immunofluorescence; IHC: immunohistochemistry; KD: knockdown; MAP1LC3/LC3: microtubule associated protein 1 light chain protein 3; MTDR: MitoTracker Deep Red; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; mtDNA: mitochondrial DNA; MTRC: MitoTracker Red CMXRos; OCR: Oxygen consumption rate; OE: overexpress; PINK1: PTEN induced kinase 1; qRT-PCR: quantitative real-time PCR; ROS: reactive oxygen species; SD: standard deviation; SOD2: superoxide dismutase 2; UQCRC2: ubiquinol-cytochrome c reductase core protein 2; WB: western blot; ΔΨ: mitochondrial membrane potential;

PCSK9 mediates the oxidative low‑density lipoprotein‑induced pyroptosis of vascularendothelialcells via the UQCRC1/ROS pathway.

The present study aimed to explore the role and mechanisms of proprotein convertase subtilisin/kexin type 9 (PCSK9) in the oxidized low-density lipoprotein (oxLDL)-induced pyroptosis of vascular endothelial cells. For this purpose, human umbilical vein endothelial cells (HUVECs) were incubated with oxLDL (100 µg/ml) for 24 h to induce pyroptosis, which was detected using PI/hoechst33342 double staining. The expression of pyroptosis-associated molecules was measured by western blot analysis and RT-qPCR. Reactive oxygen species (ROS) and membrane potential were examined through ROS probe and JC-1 staining, respectively. PCSK9 and mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) protein were knocked down by small interfering RNA (siRNA). PCSK9 was overexpressed by lentivirus. The results revealed that oxLDL induced HUVEC injury, pyroptosis and inflammatory factor release, and upregulated the expression of PCSK9 protein in the HUVECs in a concentration-dependent manner. The silencing of PCSK9 expression with siRNA suppressed the oxLDL-induced damage to HUVECs, the release of inflammatory substances and the occurrence of pyroptosis. In addition, oxLDL inhibited UQCRC1 expression, promoted mitochondrial membrane potential collapse and damaged mitochondrial function; however, these processes were reversed by the silencing of PCSK9. PCSK9 overexpression induced the pyroptosis of HUVECs, the generation of ROS and the disorder of mitochondrial function by inhibiting UQCRC1. Therefore, PCSK9 mediates the oxLDL-induced pyroptosis of vascular endothelial cells via the UQCRC1/ROS pathway.

Circular RNA hsa_circ_0000751 serves as a microRNA-488 sponge to suppress gastric cancer progression via ubiquinol-cytochrome c reductase core protein 2 regulation

ABSTRACT Circular RNAs (circRNAs) are RNA molecules that do not encode proteins but are known to regulate tumor progression. This study was designed to explore the underlying mechanism driving circRNA-mediated modulation of gastric cancer (GC). Bioinformatics analysis of gene chip GSE83521 was used to identify multiple circRNAs that were differentially regulated in matched GC and adjacent normal tissues. The circRNA with the largest variation in expression (hsa_circ_0000751) was selected for further examination. The expression profile of hsa_circ_0000751 and its target-specific interactions with microRNAs (miRNAs) and downstream gene transcripts were determined using quantitative real-time polymerase chain reaction, luciferase reporter assays, and rescue assays in human tissues and cells. The relationship between hsa_circ_0000751 expression and the clinicopathological parameters of 25 GC patients was analyzed. Furthermore, ubiquinol-cytochrome c reductase core protein 2 (UQCRC2), a GC suppressor, was detected via western blot analysis. The results showed that hsa_circ_0000751 levels were markedly downregulated in GC tissues and cell lines, which were also inversely proportional to the stage of tumor-node-metastasis (TNM) classification, tumor volume, and lymph node metastasis in GC patients. Conversely, hsa_circ_0000751 overexpression suppressed tumor progression, migration, and invasion in vitro and in vivo. From our results, we showed that hsa_circ_0000751 may serve as a miRNA sponge to suppress the activity of miR-488, thereby increasing the expression of the miR-488-target gene, UQCRC2, and limiting GC progression. Given its negative regulation of oncogenic miRNAs, the hsa_circ_0000751/miR-488/UQCRC2 axis may be crucial in the development of novel GC therapies.

Melatonin inhibits vascular endothelial cell pyroptosis by improving mitochondrial function via up-regulation and demethylation of UQCRC1.

Atherosclerosis (AS) is a chronic inflammatory disease that involves cell death and endothelial dysfunction. Melatonin is an endocrine hormone with anti-inflammatory and anti-AS effects. However, the underlying molecular mechanisms for the anti-AS effects of melatonin are unknown. A previous study has shown that pyroptosis plays a detrimental role in the development of AS, therefore, this study was designed to investigate the anti-pyroptotic effects and potential mechanisms of melatonin in atherosclerotic endothelium. Our results show that melatonin attenuated the expression of genes related to pyroptosis, including NLRP3, caspase-1, and IL-1β, in human umbilical vein endothelial cells treated with oxidized low-density lipoprotein. Furthermore, melatonin up-regulated the expression of ten-eleven translocation 2 (TET2), inhibited the methylation of ubiquinol-cytochrome c reductase core protein 1 (UQCRC1), and reduced pyroptosis. The up-regulation of UQCRC1 by melatonin improved mitochondrial function, thereby inhibiting oxidative stress and endothelial cell pyroptosis. Collectively, our results indicate that melatonin prevents endothelial cell pyroptosis by up-regulating TET2 to inhibit the methylation of UQCRC1 and improving mitochondrial function.

UQCRC1 Engages Cytochrome C for Neuronal Apoptotic Cell Death

Human Ubiquinol-Cytochrome C Reductase Core Protein 1 (UQCRC1) is an evolutionarily conserved core subunit of mitochondrial respiratory chain complex III. We recently identified the disease-associated variants of UQCRC1 from patients with familial Parkinsonism, while its function remains unclear. Here we investigate the endogenous function of UQCRC1 in human neuronal cell line and Drosophila nervous system. Flies with neuronal knockdown of uqcrc1 exhibited age-dependent parkinsonism-resembling defects, including dopaminergic neuron reduction and locomotor decline, were ameliorated by UQCRC1 expression. Lethality of uqcrc1-KO was also rescued by neuron-expression of UQCRC1 but not the disease-causing variant, providing a platform to discern the pathogenicity of this mutation. Furthermore, UQCRC1 associated with the apoptosis trigger cytochrome c (cyt-c), and uqcrc1 deficiency increased cytoplasmic fraction of cyt-c and activated the caspase cascade. RNAi of cyt-c or expression of the anti-apoptotic P35 ameliorated uqcrc1-mediated neurodegeneration. Our findings thus identify a novel role of UQCRC1 in regulating cyt-c-induced apoptosis.

Mitochondrial UQCRC1 mutations cause autosomal dominant parkinsonism with polyneuropathy

Parkinson's disease is a neurodegenerative disorder with a multifactorial aetiology. Nevertheless, the genetic predisposition in many families with multi-incidence disease remains unknown. This study aimed to identify novel genes that cause familial Parkinson's disease. Whole exome sequencing was performed in three affected members of the index family with a late-onset autosomal-dominant parkinsonism and polyneuropathy. We identified a novel heterozygous substitution c.941A>C (p.Tyr314Ser) in the mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) gene, which co-segregates with disease within the family. Additional analysis of 699 unrelated Parkinson's disease probands with autosomal-dominant Parkinson's disease and 1934 patients with sporadic Parkinson's disease revealed another two variants in UQCRC1 in the probands with familial Parkinson's disease, c.931A>C (p.Ile311Leu) and an allele with concomitant splicing mutation (c.70-1G>A) and a frameshift insertion (c.73_74insG, p.Ala25Glyfs*27). All substitutions were absent in 1077 controls and the Taiwan Biobank exome database from healthy participants (n = 1517 exomes). We then assayed the pathogenicity of the identified rare variants using CRISPR/Cas9-based knock-in human dopaminergic SH-SY5Y cell lines, Drosophila and mouse models. Mutant UQCRC1 expression leads to neurite degeneration and mitochondrial respiratory chain dysfunction in SH-SY5Y cells. UQCRC1 p.Tyr314Ser knock-in Drosophila and mouse models exhibit age-dependent locomotor defects, dopaminergic neuronal loss, peripheral neuropathy, impaired respiratory chain complex III activity and aberrant mitochondrial ultrastructures in nigral neurons. Furthermore, intraperitoneal injection of levodopa could significantly improve the motor dysfunction in UQCRC1 p.Tyr314Ser mutant knock-in mice. Taken together, our in vitro and in vivo studies support the functional pathogenicity of rare UQCRC1 variants in familial parkinsonism. Our findings expand an additional link of mitochondrial complex III dysfunction in Parkinson's disease.

Ubiquinol-cytochrome c reductase core protein 1 overexpression protects H9c2 cardiac cells against mimic ischemia/reperfusion injury through PI3K/Akt/GSK-3β pathway

Ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) plays a key role in influencing mitochondrial function. Increasing evidence supports that UQCRC1 overexpression takes part in cardioprotection. However, it remains unclear about the signaling pathway mediating the protective role of UQCRC1 overexpression. Thus, the current study aimed to investigate the signaling pathway. Inhibition of PI3K completely abolished the protective effects of UQCRC1 overexpression on cell viability and mitochondrial membrane potential after OGD or hydrogen peroxide injury in H9c2 cardiac cells, while inhibition of ERK only partially abolished these effects. Moreover, UQCRC1 overexpression dramatically increased the phosphorylation of PI3K downstream signal molecules including Akt and GSK-3β. Finally, UQCRC1 overexpression upregulated the expression of antiapoptotic protein Bcl-2, downregulated the expression of proapoptotic protein Bax, decreased active caspase 3 expression and cell apoptosis, which were completely abolished by inhibition of PI3K. In conclusion, UQCRC1 overexpression protects H9c2 cardiac cells against mimic ischemia/reperfusion injury through mediating PI3K/Akt/GSK-3β pathway to regulate apoptosis-related proteins.

Older Adults with Physical Frailty and Sarcopenia Show Increased Levels of Circulating Small Extracellular Vesicles with a Specific Mitochondrial Signature.

Mitochondrial dysfunction and systemic inflammation are major factors in the development of sarcopenia, but the molecular determinants linking the two mechanisms are only partially understood. The study of extracellular vesicle (EV) trafficking may provide insights into this relationship. Circulating small EVs (sEVs) from serum of 11 older adults with physical frailty and sarcopenia (PF&S) and 10 controls were purified and characterized. Protein levels of three tetraspanins (CD9, CD63, and CD81) and selected mitochondrial markers, including adenosine triphosphate 5A (ATP5A), mitochondrial cytochrome C oxidase subunit I (MTCOI), nicotinamide adenine dinucleotide reduced form (NADH):ubiquinone oxidoreductase subunit B8 (NDUFB8), NADH:ubiquinone oxidoreductase subunit S3 (NDUFS3), succinate dehydrogenase complex iron sulfur subunit B (SDHB), and ubiquinol-cytochrome C reductase core protein 2 (UQCRC2) were quantified by Western immunoblotting. Participants with PF&S showed higher levels of circulating sEVs relative to controls. Protein levels of CD9 and CD63 were lower in the sEV fraction of PF&S older adults, while CD81 was unvaried between groups. In addition, circulating sEVs from PF&S participants had lower amounts of ATP5A, NDUFS3, and SDHB. No signal was detected for MTCOI, NDUFB8, or UQCRC2 in either participant group. Our findings indicate that, in spite of increased sEV secretion, lower amounts of mitochondrial components are discarded through EV in older adults with PF&S. In-depth analysis of EV trafficking might open new venues for biomarker discovery and treatment development for PF&S.

Mitochondrial Signatures in Circulating Extracellular Vesicles of Older Adults with Parkinson’s Disease: Results from the EXosomes in PArkiNson’s Disease (EXPAND) Study

Systemic inflammation and mitochondrial dysfunction are involved in neurodegeneration in Parkinson’s disease (PD). Extracellular vesicle (EV) trafficking may link inflammation and mitochondrial dysfunction. In the present study, circulating small EVs (sEVs) from 16 older adults with PD and 12 controls were purified and characterized. A panel of circulating inflammatory biomolecules was measured by multiplex immunoassay. Protein levels of three tetraspanins (CD9, CD63, and CD81) and selected mitochondrial markers [adenosine triphosphate 5A (ATP5A), mitochondrial cytochrome C oxidase subunit I (MTCOI), NADH:ubiquinone oxidoreductase subunit B8 (NDUFB8), NADH:ubiquinone oxidoreductase subunit S3 (NDUFS3), succinate dehydrogenase complex iron sulfur subunit B (SDHB), and ubiquinol‐cytochrome C reductase core protein 2 (UQCRC2)] were quantified by immunoblotting. Relative to controls, PD participants showed a greater amount of circulating sEVs. Levels of CD9 and CD63 were lower in the sEV fraction of PD participants, while those of CD81 were similar between groups. Lower levels of ATP5A, NDUFS3, and SDHB were detected in sEVs from PD participants. No signal was retrieved for UQCRC2, MTCOI, or NDUFB8 in either participant group. To identify a molecular signature in circulating sEVs in relationship to systemic inflammation, a low level‐fused (multi‐platform) partial least squares ‐ discriminant analysis was applied. The model correctly classified 94.2±6.1% PD participants and 66.7±5.4% controls, and identified as relevant seven biomolecules (CD9, NDUFS3, C‐reactive protein, fibroblast growth factor 21, interleukin 9, macrophage inflammatory protein 1b, and tumor necrosis factor alpha). In conclusion, a mitochondrial signature was identified in circulating sEVs from older adults with PD, in association with a specific inflammatory profile. In‐depth characterization of sEV trafficking may allow identifying new biomarkers for PD and possible targets for personalized interventions.Support or Funding InformationInnovative Medicine Initiative‐Joint Undertaking (IMI‐JU #115621)

Mitochondrial Signatures in Circulating Extracellular Vesicles of Older Adults with Parkinson's Disease: Results from the EXosomes in PArkiNson's Disease (EXPAND) Study.

Systemic inflammation and mitochondrial dysfunction are involved in neurodegeneration in Parkinson’s disease (PD). Extracellular vesicle (EV) trafficking may link inflammation and mitochondrial dysfunction. In the present study, circulating small EVs (sEVs) from 16 older adults with PD and 12 non-PD controls were purified and characterized. A panel of serum inflammatory biomolecules was measured by multiplex immunoassay. Protein levels of three tetraspanins (CD9, CD63, and CD81) and selected mitochondrial markers (adenosine triphosphate 5A (ATP5A), mitochondrial cytochrome C oxidase subunit I (MTCOI), nicotinamide adenine dinucleotide reduced form (NADH):ubiquinone oxidoreductase subunit B8 (NDUFB8), NADH:ubiquinone oxidoreductase subunit S3 (NDUFS3), succinate dehydrogenase complex iron sulfur subunit B (SDHB), and ubiquinol-cytochrome C reductase core protein 2 (UQCRC2)) were quantified in purified sEVs by immunoblotting. Relative to controls, PD participants showed a greater amount of circulating sEVs. Levels of CD9 and CD63 were lower in the sEV fraction of PD participants, whereas those of CD81 were similar between groups. Lower levels of ATP5A, NDUFS3, and SDHB were detected in sEVs from PD participants. No signal was retrieved for UQCRC2, MTCOI, or NDUFB8 in either participant group. To identify a molecular signature in circulating sEVs in relationship to systemic inflammation, a low level-fused (multi-platform) partial least squares discriminant analysis was applied. The model correctly classified 94.2% ± 6.1% PD participants and 66.7% ± 5.4% controls, and identified seven biomolecules as relevant (CD9, NDUFS3, C-reactive protein, fibroblast growth factor 21, interleukin 9, macrophage inflammatory protein 1β, and tumor necrosis factor alpha). In conclusion, a mitochondrial signature was identified in circulating sEVs from older adults with PD, in association with a specific inflammatory profile. In-depth characterization of sEV trafficking may allow identifying new biomarkers for PD and possible targets for personalized interventions.

The miR-370/UQCRC2 axis facilitates tumorigenesis by regulating epithelial-mesenchymal transition in Gastric Cancer.

Ubiquinol-cytochrome c reductase core protein 2 (UQCRC2) is an important mitochondrial complex III subunit. This study investigated the role of UQCRC2 in gastric cancer (GC) and its upstream regulatory microRNAs (miRNAs). UQCRC2 expression levels were lower in GC tissues than non-carcinoma tissues. Furthermore, UQCRC2 levels were negatively correlated with lymph node metastasis, relapse, and tumor grade. Bioinformatics analysis predicted UQCRC2 as the target gene for miR-370, and this was verified in luciferase reporter assays. MiR-370 levels were inversely correlated with UQCRC2 levels in GC. UQCRC2 overexpression suppressed GC cell migration and invasion in vitro and in vivo, whereas up-regulating miR-370 reversed these effects. Western blotting analysis showed that miR-370 targeted UQCRC2 and positively regulated the epithelial-mesenchymal transition (EMT) signaling pathway in GC cells. Therefore, the miR-370/UQCRC2 axis may regulate EMT signaling pathways to affect tumor proliferation and metastasis and is, thus, a potential target for GC treatment.

Tryptophan Oxidation in the UQCRC1 Subunit of Mitochondrial Complex III (Ubiquinol-Cytochrome C Reductase) in a Mouse Model of Myodegeneration Causes Large Structural Changes in the Complex: A Molecular Dynamics Simulation Study

Muscle diseases display mitochondrial dysfunction and oxidative damage. Our previous study in a cardiotoxin model of myodegeneration correlated muscle damage with mitochondrial dysfunction, which in turn entailed altered mitochondrial proteome and oxidative damage of mitochondrial proteins. Proteomic identification of oxidized proteins in muscle biopsies from muscular dystrophy patients and cardiotoxin model revealed specific mitochondrial proteins to be targeted for oxidation. These included respiratory complexes which displayed oxidative modification of Trp residues in different subunits. Among these, Ubiquinol-Cytochrome C Reductase Core protein 1 (UQCRC1), a subunit of Ubiquinol-Cytochrome C Reductase Complex or Cytochrome b-c1 Complex or Respiratory Complex III displayed oxidation of Trp395, which could be correlated with the lowered activity of Complex III. We hypothesized that Trp395 oxidation might contribute to altered local conformation and overall structure of Complex III, thereby potentially leading to altered protein activity. To address this, we performed molecular dynamics simulation of Complex III (oxidized at Trp395 of UQCRC1 vs. non-oxidized control). Molecular dynamic simulation analyses revealed local structural changes in the Trp395 site. Intriguingly, oxidized Trp395 contributed to decreased plasticity of Complex III due to significant cross-talk among the subunits in the matrix-facing region and subunits in the intermembrane space, thereby leading to impaired electron flow from cytochrome C.