Sperm motility is one of the major determinants of male fertility. Since sperm need a great deal of energy to support their fast movement by active metabolism, they are thus extremely vulnerable to oxidative damage by the reactive oxygen species (ROS) and other free radicals generated as byproducts in the electron transport chain. The present study is aimed at understanding the impact of a mitochondrial oxidizing/reducing microenvironment in the etiopathology of male infertility. We detected the mitochondrial DNA (mtDNA) 4,977 bp deletion in human sperm. We examined the gene mutation of ATP synthase 6 (ATPase6 m.T8993G) in ATP generation, the gene polymorphisms of uncoupling protein 2 (UCP2, G-866A) in the uncoupling of oxidative phosphorylation, the role of genes such as manganese superoxide dismutase (MnSOD, C47T) and catalase (CAT, C-262T) in the scavenging system in neutralizing reactive oxygen species, and the role of human 8-oxoguanine DNA glycosylase (hOGG1, C1245G) in 8-hydroxy-2'-deoxyguanosine (8-OHdG) repair. We found that the sperm with higher motility were found to have a higher mitochondrial membrane potential and mitochondrial bioenergetics. The genotype frequencies of UCP2 G-866A, MnSOD C47T, and CAT C-262T were found to be significantly different among the fertile subjects, the infertile subjects with more than 50% motility, and the infertile subjects with less than 50% motility. A higher prevalence of the mtDNA 4,977 bp deletion was found in the subjects with impaired sperm motility and fertility. Furthermore, we found that there were significant differences between the occurrences of the mtDNA 4,977 bp deletion and MnSOD (C47T) and hOGG1 (C1245G). In conclusion, the maintenance of the mitochondrial redox microenvironment and genome integrity is an important issue in sperm motility and fertility.

• MeSH
• DNA Glycosylases genetics   metabolism   MeSH
• Gene Frequency MeSH
• Humans MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• DNA, Mitochondrial genetics   metabolism   MeSH
• Mitochondria genetics   metabolism   MeSH
• Sperm Motility physiology   MeSH
• Infertility, Male genetics   pathology   MeSH
• Oxidative Stress drug effects   MeSH
• Hydrogen Peroxide pharmacology   MeSH
• Polymorphism, Genetic MeSH
• Spermatozoa metabolism   physiology   MeSH
• Superoxide Dismutase genetics   metabolism   MeSH
• Uncoupling Protein 2 genetics   metabolism   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH

Molecular dynamics (MD) simulations of uncoupling proteins (UCP), a class of transmembrane proteins relevant for proton transport across inner mitochondrial membranes, represent a complicated task due to the lack of available structural data. In this work, we use a combination of homology modelling and subsequent microsecond molecular dynamics simulations of UCP2 in the DOPC phospholipid bilayer, starting from the structure of the mitochondrial ATP/ADP carrier (ANT) as a template. We show that this protocol leads to a structure that is impermeable to water, in contrast to MD simulations of UCP2 structures based on the experimental NMR structure. We also show that ATP binding in the UCP2 cavity is tight in the homology modelled structure of UCP2 in agreement with experimental observations. Finally, we corroborate our results with conductance measurements in model membranes, which further suggest that the UCP2 structure modeled from ANT protein possesses additional key functional elements, such as a fatty acid-binding site at the R60 region of the protein, directly related to the proton transport mechanism across inner mitochondrial membranes.

• MeSH
• Adenosine Triphosphate chemistry   metabolism   MeSH
• Ion Transport MeSH
• Protein Conformation * MeSH
• Fatty Acids chemistry   metabolism   MeSH
• Membrane Proteins chemistry   MeSH
• Mitochondrial Proteins chemistry   metabolism   MeSH
• Mice MeSH
• Amino Acid Sequence MeSH
• Molecular Dynamics Simulation * MeSH
• Protein Stability MeSH
• Uncoupling Protein 2 chemistry   metabolism   MeSH
• Protein Binding MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Pancreatic β-cells are vulnerable to oxidative stress due to their low content of redox buffers, such as glutathione, but possess a rich content of thioredoxin, peroxiredoxin, and other proteins capable of redox relay, transferring redox signaling. Consequently, it may be predicted that cytosolic antioxidants could interfere with the cytosolic redox signaling and should not be recommended for any potential therapy. In contrast, mitochondrial matrix-targeted antioxidants could prevent the primary oxidative stress arising from the primary superoxide sources within the mitochondrial matrix, such as at the flavin (IF) and ubiquinone (IQ) sites of superoxide formation within respiratory chain complex I and the outer ubiquinone site (IIIQ) of complex III. Therefore, using time-resolved confocal fluorescence monitoring with MitoSOX Red, we investigated various effects of mitochondria-targeted antioxidants in model pancreatic β-cells (insulinoma INS-1E cells) and pancreatic islets. Both SkQ1 (a mitochondria-targeted plastoquinone) and a suppressor of complex III site Q electron leak (S3QEL) prevented superoxide production released to the mitochondrial matrix in INS-1E cells with stimulatory glucose, where SkQ1 also exhibited an antioxidant role for UCP2-silenced cells. SkQ1 acted similarly at nonstimulatory glucose but not in UCP2-silenced cells. Thus, UCP2 can facilitate the antioxidant mechanism based on SkQ1+ fatty acid anion- pairing. The elevated superoxide formation induced by antimycin A was largely prevented by S3QEL, and that induced by rotenone was decreased by SkQ1 and S3QEL and slightly by S1QEL, acting at complex I site Q. Similar results were obtained with the MitoB probe, for the LC-MS-based assessment of the 4 hr accumulation of reactive oxygen species within the mitochondrial matrix but for isolated pancreatic islets. For 2 hr INS-1E incubations, some samples were influenced by the cell death during the experiment. Due to the frequent dependency of antioxidant effects on metabolic modes, we suggest a potential use of mitochondria-targeted antioxidants for the treatment of prediabetic states after cautious nutrition-controlled tests. Their targeted delivery might eventually attenuate the vicious spiral leading to type 2 diabetes.

• MeSH
• Antioxidants pharmacology   MeSH
• Insulin-Secreting Cells drug effects   metabolism   pathology   MeSH
• Phenanthridines MeSH
• Cells, Cultured MeSH
• Mitochondrial Membranes drug effects   metabolism   pathology   MeSH
• Mitochondria drug effects   metabolism   pathology   MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Organophosphorus Compounds MeSH
• Oxidation-Reduction MeSH
• Oxidative Stress drug effects   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Uncoupling Protein 2 metabolism   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Uncoupling protein-2, discovered in 1997, is the first described homologue of uncoupling protein-1. Uncoupling proteins increase the permeability of inner mitochondrial membrane for protons, decrease the efficiency of energy conversion, inhibit the ATP synthesis and stimulate energy release in form of heat. Uncoupling proteins also increase the substrate oxidation and reduce production of reactive oxygen species in mitochondria. The present study was conducted to assess the effects of acute treatment with triiodothyronine on uncoupling protein-2 mRNA levels in Wistar rats. Intraperitoneal injection of one dose of triiodothyronine (200 μg/kg rat body weight) increased mRNA expression of uncoupling protein-2 in liver tissue almost 2-fold after 12 h. Concentrations of total triiodothyronine and free triiodothyronine in serum were increased 122-fold and 76-fold, respectively. These results suggest that gene coding uncoupling protein-2 is gene inducible in the liver shortly after single administration of T3. Data about the kinetics of T3 mediated induction of UCP-2 mRNA during the first 24 h after treatment were not available in literature so far and therefore constitute our priority findings.

• MeSH
• Energy Metabolism MeSH
• Gene Expression MeSH
• Glycerolphosphate Dehydrogenase MeSH
• Mitochondria, Liver * enzymology   genetics   metabolism   MeSH
• Liver enzymology   metabolism   drug effects   MeSH
• RNA, Messenger isolation & purification   MeSH
• Rats, Wistar MeSH
• Reactive Oxygen Species MeSH
• Triiodothyronine * pharmacokinetics   pharmacology   blood   therapeutic use   MeSH
• Uncoupling Protein 2 * drug effects   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH