Coenzyme Q4 is a functional substitute for coenzyme Q10 and can be targeted to the mitochondria.

Coenzyme Q10 (CoQ10) is an important cofactor and antioxidant for numerous cellular processes, and its deficiency has been linked to human disorders including mitochondrial disease, heart failure, Parkinson's disease, and hypertension. Unfortunately, treatment with exogenous CoQ10 is often ineffective, likely due to its extreme hydrophobicity and high molecular weight. Here, we show that less hydrophobic CoQ species with shorter isoprenoid tails can serve as viable substitutes for CoQ10 in human cells. We demonstrate that CoQ4 can perform multiple functions of CoQ10 in CoQ-deficient cells at markedly lower treatment concentrations, motivating further investigation of CoQ4 as a supplement for CoQ10 deficiencies. In addition, we describe the synthesis and evaluation of an initial set of compounds designed to target CoQ4 selectively to mitochondria using triphenylphosphonium. Our results indicate that select versions of these compounds can successfully be delivered to mitochondria in a cell model and be cleaved to produce CoQ4, laying the groundwork for further development.

A new direction in Chinese herbal medicine ameliorates for type 2 diabetes mellitus: Focus on the potential of mitochondrial respiratory chain complexes.

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetes is a common chronic disease. Chinese herbal medicine (CHM) has a history of several thousand years in the treatment of diabetes, and active components with hypoglycemic effects extracted from various CHM, such as polysaccharides, flavonoids, terpenes, and steroidal saponins, have been widely used in the treatment of diabetes. AIM OF THE STUDY: Research exploring the potential of various CHM compounds to regulate the mitochondrial respiratory chain complex to improve type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: The literature data were primarily obtained from authoritative databases such as PubMed, CNKI, Wanfang, and others within the last decade. The main keywords used include "type 2 diabetes mellitus", "Chinese medicine", "Chinese herbal medicine", "mitochondrial respiratory chain complex", and "mitochondrial dysfunction". RESULTS: Chinese herbal medicine primarily regulates the activity of mitochondrial respiratory chain complexes in various tissues such as liver, adipose tissue, skeletal muscle, pancreatic islets, and small intestine. It improves cellular energy metabolism through hypoglycemic, antioxidant, anti-inflammatory and lipid-modulating effects. Different components of CHM can regulate the same mitochondrial respiratory chain complexes, while the same components of a particular CHM can regulate different complex activities. The active components of CHM target different mitochondrial respiratory chain complexes, regulate their aberrant changes and effectively improve T2DM and its complications. CONCLUSION: Chinese herbal medicine can modulate the function of mitochondrial respiratory chain complexes in various cell types and exert their hypoglycemic effects through various mechanisms. CHM has significant therapeutic potential in regulating mitochondrial respiratory chain complexes to improve T2DM, but further research is needed to explore the underlying mechanisms and conduct clinical trials to assess the safety and efficacy of these medications. This provides new perspectives and opportunities for personalized improvement and innovative developments in diabetes management.

Moxibustion improves hypothalamus Aqp4 polarization in APP/PS1 mice: Evidence from spatial transcriptomics.

Aquaporin-4 (AQP4) is highly polarized to perivascular astrocytic endfeet. Loss of AQP4 polarization is associated with many diseases. In Alzheimer's disease (AD), AQP4 loses its normal location and thus reduces the clearance of amyloid-ß plaques and tau protein. Clinical and experimental studies showed that moxibustion can improve the learning and memory abilities of AD. To explore whether moxibustion can affect the polarization of AQP4 around the blood-brain barrier (BBB), we used spatial transcriptomics (ST) to analyze the expression and polarization of Aqp4 in wild-type mice, APP/PS1 mice, and APP/PS1 mice intervened by moxibustion. The results showed that moxibustion improved the loss of abnormal polarization of AQP4 in APP/PS1 mice, especially in the hypothalamic BBB. Besides, the other 31 genes with Aqp4 as the core have similar depolarization in APP/PS1 mice, most of which are also membrane proteins. The majority of them have been reversed by moxibustion. At the same time, we employed the cerebrospinal fluid circulation gene set, which was found to be at a higher level in the group of APP/PS1 mice with moxibustion treatment. Finally, to further explore its mechanism, we analyzed the mitochondrial respiratory chain complex enzymes closely related to energy metabolism and found that moxibustion can significantly increase the expression of mitochondrial respiratory chain enzymes such as Cox6a2 in the hypothalamus, which could provide energy for mRNA transport. Our research shows that increasing the polarization of hypothalamic Aqp4 through mitochondrial energy supply may be an important target for moxibustion to improve cognitive impairment in APP/PS1 mice.

Methylglyoxal-mediated Gpd1 activation restores the mitochondrial defects in a yeast model of mitochondrial DNA depletion syndrome.

Human MPV17, an evolutionarily conserved mitochondrial inner-membrane channel protein, accounts for the tissue-specific mitochondrial DNA depletion syndrome. However, the precise molecular function of the MPV17 protein is still elusive. Previous studies showed that the mitochondrial morphology and cristae organization are severely disrupted in the MPV17 knockout cells from yeast, zebrafish, and mammalian tissues. As mitochondrial cristae morphology is strictly regulated by the membrane phospholipids composition, we measured mitochondrial membrane phospholipids (PLs) levels in yeast Saccharomyces cerevisiae MPV17 ortholog, SYM1 (Stress-inducible Yeast MPV17) deleted cells. We found that Sym1 knockout decreases the mitochondrial membrane PL, phosphatidyl ethanolamine (PE), and inhibits respiratory growth at 37 ̊C on rich media. Both the oxygen consumption rate and the steady state expressions of mitochondrial complex II and super-complexes are compromised. Apart from mitochondrial PE defect a significant depletion of mitochondrial phosphatidyl-choline (PC) was noticed in the sym1∆ cells grown on synthetic media at both 30 ̊C and 37 ̊C temperatures. Surprisingly, exogenous supplementation of methylglyoxal (MG), an intrinsic side product of glycolysis, rescues the respiratory growth of Sym1 deficient yeast cells. Using a combination of molecular biology and lipid biochemistry, we uncovered that MG simultaneously restores both the mitochondrial PE/PC levels and the respiration by enhancing cytosolic NAD-dependent glycerol-3-phosphate dehydrogenase 1 (Gpd1) enzymatic activity. Further, MG is incapable to restore respiratory growth of the sym1∆gpd1∆ double knockout cells. Thus, our work provides Gpd1 activation as a novel strategy for combating Sym1 deficiency and PC/PE defects.

Quantitative Proteome Analysis Reveals Melissa officinalis Extract Targets Mitochondrial Respiration in Colon Cancer Cells.

Melissa officinalis (MO), known as lemon balm, is a popular ingredient blended in herbal tea. In recent decades, the bioactivities of MO have been studied in sub-health and pathological status, highlighting MO possesses multiple pharmacological effects. We previously showed that hot water MO extract exhibited anticancer activity in colorectal cancer (CRC). However, the detailed mechanisms underlying MO-induced cell death remain elusive. To elucidate the anticancer regulation of MO extract in colon cancer, a data-driven analysis by proteomics approaches and bioinformatics analysis was applied. An isobaric tandem mass tags-based quantitative proteome analysis using liquid chromatography-coupled tandem mass spectrometry was performed to acquire proteome-wide expression data. The over-representation analysis and functional class scoring method were implemented to interpret the MO-induced biological regulations. In total, 3465 quantifiable proteoforms were identified from 24,348 peptides, with 67 upregulated and 54 downregulated proteins in the MO-treated group. Mechanistically, MO impeded mitochondrial respiratory electron transport by triggering a reactive oxygen species (ROS)-mediated oxidative stress response. MO hindered the mitochondrial membrane potential by reducing the protein expression in the electron transport chain, specifically the complex I and II, which could be restored by ROS scavenger. The findings comprehensively elucidate how MO hot water extract activates antitumor effects in colorectal cancer (CRC) cells.

S1P defects cause a new entity of cataract, alopecia, oral mucosal disorder, and psoriasis-like syndrome.

In this report, we discovered a new entity named cataract, alopecia, oral mucosal disorder, and psoriasis-like (CAOP) syndrome in two unrelated and ethnically diverse patients. Furthermore, patient 1 failed to respond to regular treatment. We found that CAOP syndrome was caused by an autosomal recessive defect in the mitochondrial membrane-bound transcription factor peptidase/site-1 protease (MBTPS1, S1P). Mitochondrial abnormalities were observed in patient 1 with CAOP syndrome. Furthermore, we found that S1P is a novel mitochondrial protein that forms a trimeric complex with ETFA/ETFB. S1P enhances ETFA/ETFB flavination and maintains its stability. Patient S1P variants destabilize ETFA/ETFB, impair mitochondrial respiration, decrease fatty acid ß-oxidation activity, and shift mitochondrial oxidative phosphorylation (OXPHOS) to glycolysis. Mitochondrial dysfunction and inflammatory lesions in patient 1 were significantly ameliorated by riboflavin supplementation, which restored the stability of ETFA/ETFB. Our study discovered that mutations in MBTPS1 resulted in a new entity of CAOP syndrome and elucidated the mechanism of the mutations in the new disease.

Mitochondrial Neurodegeneration.

Mitochondria are cytoplasmic organelles, which generate energy as heat and ATP, the universal energy currency of the cell. This process is carried out by coupling electron stripping through oxidation of nutrient substrates with the formation of a proton-based electrochemical gradient across the inner mitochondrial membrane. Controlled dissipation of the gradient can lead to production of heat as well as ATP, via ADP phosphorylation. This process is known as oxidative phosphorylation, and is carried out by four multiheteromeric complexes (from I to IV) of the mitochondrial respiratory chain, carrying out the electron flow whose energy is stored as a proton-based electrochemical gradient. This gradient sustains a second reaction, operated by the mitochondrial ATP synthase, or complex V, which condensates ADP and Pi into ATP. Four complexes (CI, CIII, CIV, and CV) are composed of proteins encoded by genes present in two separate compartments: the nuclear genome and a small circular DNA found in mitochondria themselves, and are termed mitochondrial DNA (mtDNA). Mutations striking either genome can lead to mitochondrial impairment, determining infantile, childhood or adult neurodegeneration. Mitochondrial disorders are complex neurological syndromes, and are often part of a multisystem disorder. In this paper, we divide the diseases into those caused by mtDNA defects and those that are due to mutations involving nuclear genes; from a clinical point of view, we discuss pediatric disorders in comparison to juvenile or adult-onset conditions. The complementary genetic contributions controlling organellar function and the complexity of the biochemical pathways present in the mitochondria justify the extreme genetic and phenotypic heterogeneity of this new area of inborn errors of metabolism known as 'mitochondrial medicine'.

Graphene oxide (GO)-based nanosheets with combined chemo/photothermal/photodynamic therapy to overcome gastric cancer (GC) paclitaxel resistance by reducing mitochondria-derived adenosine-triphosphate (ATP).

BACKGROUND: Paclitaxel (PTX) has been suggested to be a promising front-line drug for gastric cancer (GC), while P-glycoprotein (P-gp) could lead to drug resistance by pumping PTX out of GC cells. Consequently, it might be a hopeful way to combat drug resistance by inhibiting the out-pumping function of P-gp. RESULTS: In this study, we developed a drug delivery system incorporating PTX onto polyethylene glycol (PEG)-modified and oxidized sodium alginate (OSA)-functionalized graphene oxide (GO) nanosheets (NSs), called PTX@GO-PEG-OSA. Owing to pH/thermal-sensitive drug release properties, PTX@GO-PEG-OSA could induced more obvious antitumor effects on GC, compared to free PTX. With near infrared (NIR)-irradiation, PTX@GO-PEG-OSA could generate excessive reactive oxygen species (ROS), attack mitochondrial respiratory chain complex enzyme, reduce adenosine-triphosphate (ATP) supplement for P-gp, and effectively inhibit P-gp's efflux pump function. Since that, PTX@GO-PEG-OSA achieved better therapeutic effect on PTX-resistant GC without evident toxicity. CONCLUSIONS: In conclusion, PTX@GO-PEG-OSA could serve as a desirable strategy to reverse PTX's resistance, combined with chemo/photothermal/photodynamic therapy.

Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA): An Unconventional Mitochondrial Disorder.

Mitochondrial disorders, although heterogeneous, are traditionally described as conditions characterized by encephalomyopathy, hypotonia, and progressive postnatal organ failure. Here, we provide a systematic review of Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA), a rare, unconventional mitochondrial disorder which presents as a developmental disease; its main clinical features include microphthalmia with different degrees of severity, linear skin lesions, and central nervous system malformations. The molecular basis of this disorder has been elusive for several years. Mutations were eventually identified in three X-linked genes, i.e., HCCS, COX7B, and NDUFB11, which are all endowed with defined roles in the mitochondrial respiratory chain. A peculiar feature of this condition is its inheritance pattern: X-linked dominant male-lethal. Only female or XX male individuals can be observed, implying that nullisomy for these genes is incompatible with normal embryonic development in mammals. All three genes undergo X-inactivation that, according to our hypothesis, may contribute to the extreme variable expressivity observed in this condition. We propose that mitochondrial dysfunction should be considered as an underlying cause in developmental disorders. Moreover, LSDMCA should be taken into consideration by clinicians when dealing with patients with microphthalmia with or without associated skin phenotypes.

Mitochondrial Structure and Bioenergetics in Normal and Disease Conditions.

Mitochondria are ubiquitous intracellular organelles found in almost all eukaryotes and involved in various aspects of cellular life, with a primary role in energy production. The interest in this organelle has grown stronger with the discovery of their link to various pathologies, including cancer, aging and neurodegenerative diseases. Indeed, dysfunctional mitochondria cannot provide the required energy to tissues with a high-energy demand, such as heart, brain and muscles, leading to a large spectrum of clinical phenotypes. Mitochondrial defects are at the origin of a group of clinically heterogeneous pathologies, called mitochondrial diseases, with an incidence of 1 in 5000 live births. Primary mitochondrial diseases are associated with genetic mutations both in nuclear and mitochondrial DNA (mtDNA), affecting genes involved in every aspect of the organelle function. As a consequence, it is difficult to find a common cause for mitochondrial diseases and, subsequently, to offer a precise clinical definition of the pathology. Moreover, the complexity of this condition makes it challenging to identify possible therapies or drug targets.

Impaired Brain Mitochondrial Bioenergetics in the Ts65Dn Mouse Model of Down Syndrome Is Restored by Neonatal Treatment with the Polyphenol 7,8-Dihydroxyflavone.

Down syndrome (DS), a major genetic cause of intellectual disability, is characterized by numerous neurodevelopmental defects. Previous in vitro studies highlighted a relationship between bioenergetic dysfunction and reduced neurogenesis in progenitor cells from the Ts65Dn mouse model of DS, suggesting a critical role of mitochondrial dysfunction in neurodevelopmental alterations in DS. Recent in vivo studies in Ts65Dn mice showed that neonatal supplementation (Days P3-P15) with the polyphenol 7,8-dihydroxyflavone (7,8-DHF) fully restored hippocampal neurogenesis. The current study was aimed to establish whether brain mitochondrial bioenergetic defects are already present in Ts65Dn pups and whether early treatment with 7,8-DHF positively impacts on mitochondrial function. In the brain and cerebellum of P3 and P15 Ts65Dn pups we found a strong impairment in the oxidative phosphorylation apparatus, resulting in a deficit in mitochondrial ATP production and ATP content. Administration of 7,8-DHF (dose: 5 mg/kg/day) during Days P3-P15 fully restored bioenergetic dysfunction in Ts65Dn mice, reduced the levels of oxygen radicals and reinstated the hippocampal levels of PGC-1α. No pharmacotherapy is available for DS. From current findings, 7,8-DHF emerges as a treatment with a good translational potential for improving mitochondrial bioenergetics and, thus, mitochondria-linked neurodevelopmental alterations in DS.

A value-added application of eugenol as acaricidal agent: The mechanism of action and the safety evaluation.

Introduction: Eugenol is a major component of essential oils of several plants, it exhibits significant antiparasitic and acaricidal activities, yet its molecular targets remain unknown. Objectives: We aimed to systematically investigate the mechanism of action and the potential targets of eugenol against P. cuniculi, and evaluate the safety for laying the theoretical foundation for clinical application as an acaricide. Methods: Using RNA-Seq analysis, surface plasmon resonance analysis and RNA interference assay, the mode of action of eugenol against Psoroptes cuniculi was investigated. The effect on the mitochondrial membrane potential and complex I of PC12 cells and C6/36 cells was assayed to investigate the species specificity of eugenol in insects and mammals. Finally, a safety evaluation of eugenol in vivo was performed. Results: Eugenol inhibited complex I activity of the mitochondrial respiratory chain in the oxidative phosphorylation pathway by binding to NADH dehydrogenase chain 2 and resulted in the death of mites. The inhibition rates were 37.89% for 50 µg/mL and 60.26% for 100 µg/mL, respectively. Further experiments indicated that the difference in the complex I sequence between insects and mammals led to the different affinity of eugenol to specific peptide, resulting in species specificity. Eugenol exhibited significant inhibitory effects against the mitochondrial membrane potential and complex I in Aedes albopictus C6/36 cells but was not active in rat PC12 cells. Insect cells were particularly sensitive to eugenol. In contrast to the known inhibitor rotenone, eugenol had better safety and did not result in Parkinson's disease or other diseases in rats. Conclusion: This is the first report on acaricidal eugenol targeting complex I of the mitochondrial respiratory chain. This work lays the foundation for the development of eugenol as an environmentally alternative acaricidal agent.

The protective effect of cordyceps sinensis extract on cerebral ischemic injury via modulating the mitochondrial respiratory chain and inhibiting the mitochondrial apoptotic pathway.

Cerebral ischemia is a common refractory brain disease, resulting from a reduction in the blood flow to the brain. Mitochondrial dysfunction leads to ischemic stroke and brain injury. Cordyceps sinensis (CS) is an important traditional Chinese medicine, which has been linked to neuroprotection in recent studies. In this study, we investigated the role of the mitochondrial respiratory chain and the mitochondrial apoptotic pathway on the protective effect of Cordyceps sinensis extract (CSE) against cerebral ischemia injury both in vivo and in vitro. In a murine middle cerebral artery occlusion (MCAO) model, administration of CSE relieved neuronal morphological damage and attenuated the neuronal apoptosis. CSE also reduced neurobehavioral scores and oxygen free radical (OFR), while improving the levels of ATP, cytochrome c oxidase (COX), and mitochondrial complexes I-IV. Furthermore, the mRNA expression of Bax, cytochrome c (Cyt c) and caspase-3 were down-regulated. In brain microvascular endothelial cells (BMECs) exposed to oxygen and glucose deprivation (OGD), CSE prevented OGD-induced cellular apoptosis, and recovered the reduction of mitochondrial membrane potential (MMP). Moreover, CSE treatment induced an increase of Bcl-2 protein expression and a decrease of Bax, Cyt c and caspase-3 protein expression. Meanwhile, the caspase-3, -8, and -9 activities were also inhibited. The results indicate that CSE can relieve cerebral ischemia injury and exhibit protective effects via modulating the mitochondrial respiratory chain and inhibiting the mitochondrial apoptotic pathway.

Mitochondrial OXPHOS is involved in the protective effects of L-arginine against heat-induced low sperm motility of boar.

The present study aimed to analyze the time- and temperature-responses of boar sperm and clarify the mechanism underlying the protective effects of L-arginine on heat-induced low sperm motility. Mature boar sperm was used to evaluate the effects of temperature, exposure time, L-arginine level and their interactions on sperm motility, respectively. Results showed increasing exposure time resulted in the decreased total motility and rate of rapid progressive sperm, and the increased rates of the immotile sperm and the sperm shaking in place at 38 and 39 °C, respectively (P < 0.05). L-arginine supplementation at the dose of 1.0 mM increased total motility and decreased rate of immotile sperm (P < 0.05). Heat at 39 °C decreased total motile and rate of rapid progressive sperm (P < 0.05), increased the level of sperm reactive oxygen species (ROS) (P < 0.05), reduced mitochondrial membrane potential (ΔΨm), ATP content and the activities of mitochondrial respiratory chain complexes (MRCC) ΙΙΙ and V (P < 0.05), which were attenuated by L-arginine supplementation. There were significant increases in the relative mRNA expression of nuclear respiratory factor 1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha in heat-exposed group without L-arginine supplementation. In conclusion, the rising temperatures impacted boar sperm motility in a time-dependent manner. In vitro addition of L-arginine to boar semen had a dose-dependent effect on sperm motility and sperm incubated with 1.0 mM L-arginine showed elevated motility. L-arginine supplementation can ameliorate heat-induced increase in ROS level and decreases in MRCC activities, which further maintain mitochondrial oxidative phosphorylation function, ATP synthesis and boar sperm motility.

Effects of new tetrahydroquinoline-isoxazole hybrids on bioenergetics of hepatocarcinoma Hep-G2 cells and rat liver mitochondria.

New molecular hybrids were synthesized by combining tetrahydroquinoline (THQ) and isoxazole (ISX) scaffolds, in search for chemical structures with improved pharmacological properties. Our tetrahydroquinoline (THQ) and isoxazole (ISX) hybrids differ in the X and Y substituents: FM53 (X = H; Y= H), FM49 (X = CH3; Y= OCH3), FM50 (X = Cl; Y= H) and FM48 (X = Cl; Y= OCH3). Aiming at exploring their bioactivity in liver cancer cells, in this paper we report the effect of four THQ-ISX hybrids on viability, respiration and oxidative stress in Hep-G2 human hepatoma cells. In addition, we measured the alterations induced by these compounds on oxygen uptake and respiratory chain enzymes in isolated mitochondria. Cell viability assay indicated that these THQ-ISX hybrids displayed antiproliferative activity on Hep-G2 cells. Among these, FM50 (IC50 = 5.2 ±â€¯1.9 µM) and FM53 (IC50 = 6.8 ±â€¯0.7 µM) had the highest cytotoxicity. These four hybrids also inhibited the Hep-G2 cells respiration in the uncoupled state, with FM50 decreasing all respiratory states (basal, leak, uncoupled). While only FM49 and FM53 altered the Hep-G2 cells redox function. In terms of mitochondrial bioenergetics, THQ-ISX hybrids decreased the oxygen consumption in state 3 (via complex I and II), and also inhibited NADH oxidase and NADH cytochrome c reductase enzyme activities. In these experiments, the structural homologues FM50 and FM53 had a remarkable inhibitory effect (~50%) with respect to FM49 and FM48. These results show that THQ-ISX hybrids are promising compounds for hepatoma cancer treatment and that the phenyl substituent (Y= H) in the ISX scaffold intensifies both, the cytotoxicity in Hep-G2 cells and, inhibition of electron transport through complex I of the mitochondrial respiratory chain.

Proteomic analysis of oxidized proteins in the brain and liver of the Nile tilapia (Oreochromis niloticus) exposed to a water-accommodated fraction of Maya crude oil.

Crude oil (CO) is a super mixture of chemical compounds whose toxic effects are reported in fish species according to international guidelines. In the current study a proteomic analysis of oxidized proteins (ox) was performed on the brain and liver of Nile tilapia exposed to WAF obtained from relevant environmental loads (0.01, 0.1 and 1.0 g/L) of Maya CO. Results have shown that oxidation of specific proteins was a newly discovered organ-dependent process able to disrupt key functions in Nile tilapia. In control fish, enzymes involved on aerobic metabolism (liver aldehyde dehydrogenase and brain dihydrofolate reductase) and liver tryptophan--tRNA ligase were oxidized. In WAF-treated liver specimens, fructose-bisphosphate aldolase (FBA), ß-galactosidase (ß-GAL) and dipeptidyl peptidase 9 (DPP-9) were detected in oxidized form. oxDPP-9 could be favorable by reducing the risk associated with altered glucose metabolism, the opposite effects elicited by oxFBA and oxß-GAL. oxTrypsin showed a clear adverse effect by reducing probably the hepatocyte capacity to achieve proteolysis of oxidized proteins as well as for performing the proper digestive function. Additionally, enzyme implicated in purine metabolism adenosine (deaminase) was oxidized. Cerebral enzymes of mitochondrial respiratory chain complex (COX IV, COX5B), of glycosphingolipid biosynthesis (ß-N-acetylhexosaminidase), involved in catecholamines degradation (catechol O-methyltransferase), and microtubule cytoskeleton (stathmin) were oxidized in WAF-treated specimens. This response suggests, in the brain, an adverse scenario for the mitochondrial respiration process and for ATP provision as for ischemia/reoxygenation challenges. Proteomic analysis of oxidized proteins is a promising tool for monitoring environmental quality influenced by hydrocarbons dissolved in water.

Ethanolamine ameliorates mitochondrial dysfunction in cardiolipin-deficient yeast cells.

Cardiolipin (CL) is a signature phospholipid of the mitochondria required for the formation of mitochondrial respiratory chain (MRC) supercomplexes. The destabilization of MRC supercomplexes is the proximal cause of the pathology associated with the depletion of CL in patients with Barth syndrome. Thus, promoting supercomplex formation could ameliorate mitochondrial dysfunction associated with CL depletion. However, to date, physiologically relevant small-molecule regulators of supercomplex formation have not been identified. Here, we report that ethanolamine (Etn) supplementation rescues the MRC defects by promoting supercomplex assembly in a yeast model of Barth syndrome. We discovered this novel role of Etn while testing the hypothesis that elevating mitochondrial phosphatidylethanolamine (PE), a phospholipid suggested to overlap in function with CL, could compensate for CL deficiency. We found that the Etn supplementation rescues the respiratory growth of CL-deficient Saccharomyces cerevisiae cells in a dose-dependent manner but independently of its incorporation into PE. The rescue was specifically dependent on Etn but not choline or serine, the other phospholipid precursors. Etn improved mitochondrial function by restoring the expression of MRC proteins and promoting supercomplex assembly in CL-deficient cells. Consistent with this mechanism, overexpression of Cox4, the MRC complex IV subunit, was sufficient to promote supercomplex formation in CL-deficient cells. Taken together, our work identifies a novel role of a ubiquitous metabolite, Etn, in attenuating mitochondrial dysfunction caused by CL deficiency.

An infant case of diffuse cerebrospinal lesions and cardiomyopathy caused by a BOLA3 mutation.

INTRODUCTION: Mitochondrial dysfunction results in a wide range of organ disorders through diverse genetic abnormalities. We herein present the detailed clinical course of an infant admitted for extensive, rapidly progressing white matter lesions and hypertrophic cardiomyopathy due to a BOLA3 gene mutation. CASE: A 6-month-old girl with no remarkable family or past medical history until 1 month prior presented with developmental regression and feeding impairment. Ultrasound cardiography and brain magnetic resonance imaging (MRI) respectively disclosed the presence of hypertrophic cardiomyopathy and symmetrical deep white matter lesions. She was transferred to our hospital at age 6 months. High lactate levels in her cerebrospinal fluid suggested mitochondrial dysfunction. Despite vitamin supplementation therapy followed by a ketogenic diet, the patient began exhibiting clusters of myoclonic seizures and respiratory failure. Brain and spinal cord MRI revealed rapid progression of the white matter lesions. She died at 10 months of age. Fibroblasts obtained pre-mortem displayed low mitochondrial respiratory chain complex I and II activity. A homozygous H96R (c. 287 A > G) mutation was identified in the BOLA3 gene. DISCUSSION: No reported case of a homozygous BOLA3 gene mutation has survived past 1 year of life. BOLA3 appears to play a critical role in the electron transport system and production of iron-sulfur clusters that are related to lipid metabolism and enzyme biosynthesis.

COX16 is required for assembly of cytochrome c oxidase in human cells and is involved in copper delivery to COX2.

Cytochrome c oxidase (COX), complex IV of the mitochondrial respiratory chain, is comprised of 14 structural subunits, several prosthetic groups and metal cofactors, among which copper. Its biosynthesis involves a number of ancillary proteins, encoded by the COX-assembly genes that are required for the stabilization and membrane insertion of the nascent polypeptides, the synthesis of the prosthetic groups, and the delivery of the metal cofactors, in particular of copper. Recently, a modular model for COX assembly has been proposed, based on the sequential incorporation of different assembly modules formed by specific subunits. We have cloned and characterized the human homologue of yeast COX16. We show that human COX16 encodes a small mitochondrial transmembrane protein that faces the intermembrane space and is highly expressed in skeletal and cardiac muscle. Its knockdown in C. elegans produces COX deficiency, and its ablation in HEK293 cells impairs COX assembly. Interestingly, COX16 knockout cells retain significant COX activity, suggesting that the function of COX16 is partially redundant. Analysis of steady-state levels of COX subunits and of assembly intermediates by Blue-Native gels shows a pattern similar to that reported in cells lacking COX18, suggesting that COX16 is required for the formation of the COX2 subassembly module. Moreover, COX16 co-immunoprecipitates with COX2. Finally, we found that copper supplementation increases COX activity and restores normal steady state levels of COX subunits in COX16 knockout cells, indicating that, even in the absence of a canonical copper binding motif, COX16 could be involved in copper delivery to COX2.

Assessing the anthelmintic activity of pyrazole-5-carboxamide derivatives against Haemonchus contortus.

BACKGROUND: In this study, we tested five series of pyrazole-5-carboxamide compounds (n = 55) for activity against parasitic stages of the nematode Haemonchus contortus (barber's pole worm), one of the most pathogenic parasites of ruminants. METHODS: In an optimised, whole-organism screening assay, using exsheathed third-stage (xL3) and fourth-stage (L4) larvae, we measured the inhibition of larval motility and development of H. contortus. RESULTS: Amongst the 55 compounds, we identified two compounds (designated a-15 and a-17) that reproducibly inhibit xL3 motility as well as L4 motility and development, with IC50 values ranging between ~3.4 and 55.6 µM. We studied the effect of these two 'hit' compounds on mitochondrial function by measuring oxygen consumption. This assessment showed that xL3s exposed to each of these compounds consumed significantly less oxygen and had less mitochondrial activity than untreated xL3s, which was consistent with specific inhibition of complex I of the respiratory electron transport chain in arthropods. CONCLUSIONS: The present findings provide a sound basis for future work, aimed at identifying the targets of compounds a-15 and a-17 and establishing the modes of action of these chemicals in H. contortus.