Subcomplex Iλ Specifically Controls Integrated Mitochondrial Functions in Caenorhabditis elegans

Complex I dysfunction is a common, heterogeneous cause of human mitochondrial disease having poorly understood pathogenesis. The extensive conservation of complex I composition between humans and Caenorhabditis elegans permits analysis of individual subunit contribution to mitochondrial functions at both the whole animal and mitochondrial levels. We provide the first experimentally-verified compilation of complex I composition in C. elegans, demonstrating 84% conservation with human complex I. Individual subunit contribution to mitochondrial respiratory capacity, holocomplex I assembly, and animal anesthetic behavior was studied in C. elegans by RNA interference-generated knockdown of nuclear genes encoding 28 complex I structural subunits and 2 assembly factors. Not all complex I subunits directly impact respiratory capacity. Subcomplex Iλ subunits along the electron transfer pathway specifically control whole animal anesthetic sensitivity and complex II upregulation, proportionate to their relative impairment of complex I-dependent oxidative capacity. Translational analysis of complex I dysfunction facilitates mechanistic understanding of individual gene contribution to mitochondrial disease. We demonstrate that functional consequences of complex I deficiency vary with the particular subunit that is defective

Mitochondrial DNA quantity changes in leucocytes of cancer patients on cisplatin and 5-fluorouracil regimen

Purpose: Cisplatin and 5-Fluorouracil are the critical components of therapeutic regimen in a broad range of malignancies. Their therapeutic efficacy is limited due to the development of toxic side effects and drug resistance by the cancer cells. Cisplatin toxic side effects are usually associated with mitochondrial injury in vivo and in vitro. In vitro evidence indicates that cisplatin decreases mitochondrial DNA (mtDNA) copy number. There is limited information on the effect of cisplatin on human mtDNA quantity. In order to clarify the effects of cisplatin and 5-FU on mtDNA in human, this study focused on the changes of mtDNA quantitation in cancer patients who were treated with cisplatin-based regimens. Methods: 24 blood samples from head and neck cancer patients were collected before chemotherapy and after second cycle of chemotherapy. Total DNA was extracted from peripheral blood leukocytes by salting out method. Validation of primer pairs were done by conventional PCR and checked by gel electrophoresis. The relative changes of mtDNA quantity were determined by quantitative PCR targeting Cyt-B genes normalizing with the nuclear gene PARL. Result: Comparing 24 samples, there was an increased mtDNA level after second cycle of chemotherapy, though it did Wilcoxon signed ranked test). However, 58% of the total patients had relatively increased mtDNA amount while 42% of the total patients showed decreased mtDNA amount after second cycle of chemotherapy (P<0.05, paired t-test). Conclusion: Overall, Cisplatin-based chemotherapy can affect mtDNA quantity changes in leucocytes of head and neck cancer patients

Antioxidant-Enhancing Property of the Polar Fraction of Mangosteen Pericarp Extract and Evaluation of Its Safety in Humans

Crude extract from the pericarp of the mangosteen (mangosteen extract [ME]) has exhibited several medicinal properties in both animal models and human cell lines. Interestingly, the cytotoxic activities were always observed in nonpolar fraction of the extract whereas the potent antioxidant was often found in polar fraction. Although it has been demonstrated that the polar fraction of ME exhibited the antioxidant activity, the safety of the polar fraction of ME has never been thoroughly investigated in humans. In this study, we investigated the safety of oral administration of the polar fraction of ME in 11 healthy Thai volunteers. During a 24-week period of the study, only minor and tolerable side effects were reported; no serious side effects were documented. Blood chemistry studies also showed no liver damage or kidney dysfunction in all subjects. We also demonstrated antioxidant property of the polar fraction of ME both in vitro and in vivo. Interestingly, oral administration of the polar fraction of ME enhanced the antioxidant capability of red blood cells and decreased oxidative damage to proteins within red blood cells and whole blood

A Drosophila model of mitochondrial disease caused by a complex I mutation that uncouples proton pumping from electron transfer

Mutations affecting mitochondrial complex I, a multi-subunit assembly that couples electron transfer to proton pumping, are the most frequent cause of heritable mitochondrial diseases. However, the mechanisms by which complex I dysfunction results in disease remain unclear. Here, we describe a Drosophila model of complex I deficiency caused by a homoplasmic mutation in the mitochondrial-DNA-encoded NADH dehydrogenase subunit 2 (ND2) gene. We show that ND2 mutants exhibit phenotypes that resemble symptoms of mitochondrial disease, including shortened lifespan, progressive neurodegeneration, diminished neural mitochondrial membrane potential and lower levels of neural ATP. Our biochemical studies of ND2 mutants reveal that complex I is unable to efficiently couple electron transfer to proton pumping. Thus, our study provides evidence that the ND2 subunit participates directly in the proton pumping mechanism of complex I. Together, our findings support the model that diminished respiratory chain activity, and consequent energy deficiency, are responsible for the pathogenesis of complex-I-associated neurodegeneration

PCR-Based Diagnosis of Neoscytalidium dimidiatum Infection Using Internal Transcribed Spacer 1 Region of Ribosomal DNA Primers

Objective: To develop N. dimidiatum-specific single PCR-based identification with DNA sequences of nuclear ribosomal internal transcribed spacer (ITS) 1 region primers to facilitate the rapid and accurate detection of N. dimidiatum. Methods: N. dimidiatum-specific PCR primers were designed based on the sequence of the internal transcribed spacer 1 region, which is located between 18S and 5.8S nuclear rDNA. Fungal DNA extracted from common causative species for superficial fungal infection including: 2 strains of N. dimidiatum, 9 species of dermatophyte (DMP) and 25 species of non-dermatophyte (NDM) colonies grown on culture plates were used for PCR analysis. Also, 30 clinical specimens collected from 30 patients clinically diagnosed with fungal nail and feet infection who attended Dermatology clinic Siriraj Hospital during October 2015 to November 2015 were used for PCR assay. Results: Using N. dimidiatum-specific PCR primers, the PCR product was amplified from two standard strains of N. dimidiatum, and there was no amplification from other DMP or NDM species. Regarding sensitivity as lower limit of detection, this PCR method was able to detect 10 pg of N. dimidiatum DNA with ethidium bromide staining and could detect N. dimidiatum in clinical samples. Conclusion: This newly developed N. dimidiatum-specific PCR identification system is rapid, sensitive, and specific. This diagnostic method will facilitate early and accurate diagnosis and accelerate appropriate treatment in patients with N. dimidiatum infection

Genome-wide linkage scan and association study of PARL to the expression of LHON families in Thailand

Leber hereditary optic neuropathy (LHON) is the most common mitochondrially inherited disease causing blindness, preferentially in young adult males. Most of the patients carry the G11778A mitochondrial DNA (mtDNA) mutation. However, the marked incomplete penetrance and the gender bias indicate some additional genetic and/or environmental factors to disease expression. Herein, we first conducted a genome-wide linkage scan with 400 microsatellite markers in 9 large Thai LHON G11778A pedigrees. Using an affecteds-only nonparametric linkage analysis, 4 regions on chromosomes 3, 12, 13 and 18 showed Zlr scores greater than 2 (P2 in 10 of 16 allele sharing models tested) was then expanded to include the region 3q26.2-3q28 covering SLC7A14 (3q26.2), MFN1 (3q26.32), MRPL47 (3q26.33), MCCC1 (3q27.1), PARL (3q27.1) and OPA1 (3q28-q29). All of these candidate genes were selected from the Maestro database and had known to be localized in mitochondria. Sixty tag SNPs were genotyped in 86 cases, 211 of their relatives and 32 unrelated Thai controls, by multiplex-PCR-based Invader assay. Analyses using a powerful association testing tool that adjusts for relatedness (the MQLS statistic) showed the most evidence of association between two SNPs, rs3749446 and rs1402000 (located in PARL presenilins-associated rhomboid-like) and LHON expression (both P = 8.8x10-5). The mitochondrial PARL protease has been recently known to play a role with a dynamin-related OPA1 protein in preventing apoptotic events by slowing down the release of cytochrome c out of mitochondrial cristae junctions. Moreover, PARL is required to activate the intramembranous proteolyses resulting in the degradation of an accumulated proapoptotic protein in the outer mitochondrial membrane. Under these circumstances, variants of PARL are suggested to influence cell death by apoptosis which has long been believed to intrigue the neurodegeneration of LHON