Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Endometrial integrin expression in women with recurrent implantation failure after in vitro fertilization and its relationship to pregnancy outcome.

OBJECTIVE: To determine expression of integrins α₁, α₄, and αVβ₃ in the glandular and luminal epithelium, stroma, and cells in the blood vessel walls of the endometrium from women with recurrent implantation failure (RIF) and to determine if they are of prognostic value in determining pregnancy outcome. DESIGN: Prospective nonrandomized study. SETTING: Department of reproductive medicine. PATIENT(S): Forty-five women with RIF and six healthy fertile women were recruited. RIF was defined as the failure to conceive after the transfer of four good-quality embryos in three or more fresh or frozen cycles. INTERVENTION(S): Endometrial biopsy samples were obtained from women with RIF and control women on days LH+7-LH+9 of the cycle. Expression of integrins α₁, α₄, and αVβ₃ was determined by immunohistochemistry. MAIN OUTCOME MEASURE(S): A semiquantitative measurement of expression of each integrin protein in the luminal and glandular epithelium, stroma, and cells in the blood vessel walls was determined by H-score analysis. RESULT(S): Expression of integrins α₁ and α₄ was greatest in the luminal and glandular epithelial cells and the cells in the blood vessel wall, and significantly higher expression of integrins α₁ and α₄ was seen in the glandular epithelium compared with the luminal epithelium (H-scores: α₁ 293 ± 15 and 180 ± 12, α₄ 287 ± 14 and 191 ± 11, respectively). Expression of αVβ₃ in the epithelium and blood vessels was also greater than in the stroma but there was no significant difference in expression of αVβ₃ in glandular and luminal epithelium. No significant difference in H-scores was seen for α₁, α₄, and αVβ3 expression in any of the endometrial compartments in tissue from women with RIF and control women. No significant difference in α₁, α₄, and αVβ₃ expression in any compartment was observed between those who achieved a clinical pregnancy after subsequent assisted conception treatment (n = 21) and those who were unsuccessful (n = 24). CONCLUSION(S): RIF, when defined as failure to achieve a clinical pregnancy after the transfer of at least four good-quality embryos in three transfer cycles, is not associated with abnormal endometrial integrin expression. In addition, the expression of integrins α₁, α₄, and αVβ₃ appears to have no prognostic value in subsequent IVF treatment

Lipid nanoparticle-encapsulated mRNA therapy corrects serum total bilirubin level in Crigler-Najjar syndrome mouse model

Crigler-Najjar syndrome is a rare disorder of bilirubin metabolism caused by uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1) mutations characterized by hyperbilirubinemia and jaundice. No cure currently exists; treatment options are limited to phototherapy, whose effectiveness diminishes over time, and liver transplantation. Here, we evaluated the therapeutic potential of systemically administered, lipid nanoparticle-encapsulated human UGT1A1 (hUGT1A1) mRNA therapy in a Crigler-Najjar mouse model. Ugt1 knockout mice were rescued from lethal post-natal hyperbilirubinemia by phototherapy. These adult Ugt1 knockout mice were then administered a single lipid nanoparticle-encapsulated hUGT1A1 mRNA dose. Within 24 h, serum total bilirubin levels decreased from 15 mg/dL (256 μmol/L) to <0.5 mg/dL (9 μmol/L), i.e., slightly above wild-type levels. This reduction was sustained for 2 weeks before bilirubin levels rose and returned to pre-treatment levels by day 42 post-administration. Sustained reductions in total bilirubin levels were achieved by repeated administration of the mRNA product in a frequency-dependent manner. We were also able to rescue the neonatal lethality phenotype seen in Ugt1 knockout mice with a single lipid nanoparticle dose, which suggests that this may be a treatment modality appropriate for metabolic crisis situations. Therefore, lipid nanoparticle-encapsulated hUGT1A1 mRNA may represent a potential treatment for Crigler-Najjar syndrome

Bisphenol A induces DSB-ATM-p53 signaling leading to cell cycle arrest, senescence, autophagy, stress response, and estrogen release in human fetal lung fibroblasts

Experimental and/or epidemiological studies suggest that prenatal exposure to bisphenol A (BPA) may delay fetal lung development and maturation and increase the susceptibility to childhood respiratory disease. However, the underlying mechanisms remain to be elucidated. In our previous study with cultured human fetal lung fibroblasts (HFLF), we demonstrated that 24-h exposure to 1 and 100 µM BPA increased GPR30 protein in the nuclear fraction. Exposure to 100 μM BPA had no effects on cell viability, but increased cytoplasmic expression of ERβ and release of GDF-15, as well as decreased release of IL-6, ET-1, and IP-10 through suppression of NFκB phosphorylation. By performing global gene expression and pathway analysis in this study, we identified molecular pathways, gene networks, and key molecules that were affected by 100, but not 0.01 and 1 µM BPA in HFLF. Using multiple genomic and proteomic tools, we confirmed these changes at both gene and protein levels. Our data suggest that 100 μM BPA increased CYP1B1 and HSD17B14 gene and protein expression and release of endogenous estradiol, which was associated with increased ROS production and DNA double-strand breaks, upregulation of genes and/or proteins in steroid synthesis and metabolism, and activation of Nrf2-regulated stress response pathways. In addition, BPA activated ATM-p53 signaling pathway, resulting in increased cell cycle arrest at G1 phase, senescence and autophagy, and decreased cell proliferation in HFLF. The results suggest that prenatal exposure to BPA at certain concentrations may affect fetal lung development and maturation, and thereby affecting susceptibility to childhood respiratory diseases

Exposure to a northern contaminant mixture (NCM) alters hepatic energy and lipid metabolism exacerbating hepatic steatosis in obese JCR rats.

Non-alcoholic fatty liver disease (NAFLD), defined by the American Liver Society as the buildup of extra fat in liver cells that is not caused by alcohol, is the most common liver disease in North America. Obesity and type 2 diabetes are viewed as the major causes of NAFLD. Environmental contaminants have also been implicated in the development of NAFLD. Northern populations are exposed to a myriad of persistent organic pollutants including polychlorinated biphenyls, organochlorine pesticides, flame retardants, and toxic metals, while also affected by higher rates of obesity and alcohol abuse compared to the rest of Canada. In this study, we examined the impact of a mixture of 22 contaminants detected in Inuit blood on the development and progression of NAFLD in obese JCR rats with or without co-exposure to 10% ethanol. Hepatosteatosis was found in obese rat liver, which was worsened by exposure to 10% ethanol. NCM treatment increased the number of macrovesicular lipid droplets, total lipid contents, portion of mono- and polyunsaturated fatty acids in the liver. This was complemented by an increase in hepatic total cholesterol and cholesterol ester levels which was associated with changes in the expression of genes and proteins involved in lipid metabolism and transport. In addition, NCM treatment increased cytochrome P450 2E1 protein expression and decreased ubiquinone pool, and mitochondrial ATP synthase subunit ATP5A and Complex IV activity. Despite the changes in mitochondrial physiology, hepatic ATP levels were maintained high in NCM-treated versus control rats. This was due to a decrease in ATP utilization and an increase in creatine kinase activity. Collectively, our results suggest that NCM treatment decreases hepatic cholesterol export, possibly also increases cholesterol uptake from circulation, and promotes lipid accumulation and alters ATP homeostasis which exacerbates the existing hepatic steatosis in genetically obese JCR rats with or without co-exposure to ethanol

Lipid contents and contaminant levels (ng/g wt) in the liver of obese JCR rats dosed with vehicle or NCM and treated with or without ethanol.

<p><i>n</i> = 7–8, means ± SEM, 2-way ANOVA with Tukey's post-hoc test.</p>a<p>denotes statistically significant difference between vehicle (V) control and high dose (H) groups at p<0.001.</p>b<p>denotes statistically significant difference between OWV and OEV, and between OWH and OEH groups at p<0.001.</p><p>Lipid contents and contaminant levels (ng/g wt) in the liver of obese JCR rats dosed with vehicle or NCM and treated with or without ethanol.</p

NCM exposure increases hepatic creatine kinase activity and total ATPase activity, which is associated with decreases in hepatic ABCA1, CD36, and L-FABP protein expression and circulating levels of cholesterol and triglycerides.

<p><b>A</b>). Measurement of the specific activities of pyruvate kinase, creatine kinase, and total MDR ATPases in liver homogenate. For pyruvate kinase, activities were ascertained by measuring the consumption of NADH. Creatine kinase activities were measured by ADP production. <i>n</i> = 5, means ±SEM. Total MDR ATPases activities were measured using BD Gentest ATPase Assay kit. <b>B</b>) Immunoblot analysis of ABCA1 and ApoB-100 protein levels. Membranes were stripped and probed for GAPDH. Blots were quantified using ImageJ software and values were normalized to GAPDH loading control levels. <i>n</i> = 3, means ±SEM. <b>C</b>) Hepatic CD36 and L-FABP levels were measured using ELISA kits from MyBioSource. <i>n</i> = 6, means±SEM. <b>D</b>) Serum cholesterol and triglycerides levels were measured using the Hitachi Model 917 Multichannel Analyzer. <i>n</i> = 5, means ±SEM. Two-way ANOVA with Tukey's post-hoc test. *, **, and *** denotes P<0.05, 0.01 and 0.001 respectively. * denotes statistical comparison between vehicle control (V) and high dose (H) and ^# denotes statistical comparison between water (W) and ethanol (E) treated groups. OWV; obese water vehicle, OWH; obese water high dose, OEV; obese ethanol vehicle, OEH; obese ethanol high dose.</p

Contaminant levels (ng/g wt) in the sera of obese JCR rats treated with vehicle (V) or high dose (H) NCM with (E) or without (W) co-exposure to ethanol.

<p>n = 7–8, means ±SEM, 2-way ANOVA with Tukey's post-hoc test.</p>a<p>denotes statistically significant difference between vehicle (V) control and high dose (H) groups at p<0.05.</p><p>Contaminant levels (ng/g wt) in the sera of obese JCR rats treated with vehicle (V) or high dose (H) NCM with (E) or without (W) co-exposure to ethanol.</p

Pathways of hepatic cholesterol and Coenzyme Q₁₀ (CoQ10) biosynthesis in liver.

<p>Pathways of hepatic cholesterol and Coenzyme Q₁₀ (CoQ10) biosynthesis in liver.</p