ABSTRACT
The survival of a cell depends on its ability to meet its energy requirements. We hypothesized that the mitochondrial reserve respiratory capacity (RRC) of a cell is a critical component of its bioenergetics that can be utilized during an increase in energy demand, thereby, enhancing viability. Our goal was to identify the elements that regulate and contribute to the development of RRC and its involvement in cell survival. The results show that activation of metabolic sensors, including pyruvate dehydrogenase and AMP-dependent kinase, increases cardiac myocyte RRC via a Sirt3-dependent mechanism. Notably, we identified mitochondrial complex II (cII) as a target of these metabolic sensors and the main source of RRC. Moreover, we show that RRC, via cII, correlates with enhanced cell survival after hypoxia. Thus, for the first time, we show that metabolic sensors via Sirt3 maximize the cellular RRC through activating cII, which enhances cell survival after hypoxia.
Subject(s)
Electron Transport Complex II/metabolism , Mitochondria/metabolism , Muscle Cells/metabolism , Sirtuin 3/metabolism , Animals , Animals, Newborn , Cell Hypoxia/genetics , Cell Respiration/genetics , Cell Survival , Electron Transport Complex II/genetics , Gene Expression Regulation , Humans , Muscle Cells/cytology , Oxidative Phosphorylation , Phosphotransferases (Phosphate Group Acceptor)/genetics , Phosphotransferases (Phosphate Group Acceptor)/metabolism , Primary Cell Culture , Pyruvate Dehydrogenase Complex/genetics , Pyruvate Dehydrogenase Complex/metabolism , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Rats , Rats, Sprague-Dawley , Signal Transduction , Sirtuin 3/antagonists & inhibitors , Sirtuin 3/geneticsABSTRACT
BACKGROUND: Iron overload may contribute to the pathogenesis of insulin resistance. We aimed to investigate the relationship among iron stores, liver transaminases and components of the metabolic syndrome in healthy teenagers in a cross-sectional study. MATERIAL AND METHODS: We determined body mass index (BMI), waist-to-hip-ratio (WHR), blood pressure, liver ultrasound, serum lipids, insulin, fasting glucose, liver transaminase levels, hsCRP, iron parameters in 325 of 341 (95.3%) students (234 men, 16.7 +/- 1.7 years; 91 women, 16.5 +/- 1.7 years) of one single high school. Male and female study participants were allocated to increasing quartiles of body iron stores as assessed by sTfr/ferritin and alanine aminotranspeptidase (ALT) levels, and the distribution of cardiometabolic risk factors along quartiles was analysed. Regression analysis was performed to confirm the independent relationship between parameters. RESULTS: In male students, BMI, WHR, systolic and diastolic blood pressure, serum triglyceride levels and hsCRP were higher in the top sTfR/ferritin and ALT quartiles compared with the lowest quartiles (P < 0.01 for all parameters). In female students, sTfR/ferritin were not associated with antropomorphic cardiometabolic risk factors but with insulin resistance (HOMA-IR, P = 0.046). Moreover, ALT levels were independently related to BMI, waist and hip circumference, systolic blood pressure, serum triglyceride and insulin concentrations (P < 0.05 for all parameters) in female students. CONCLUSION: These results provide evidence for linkage among body iron stores, transaminase activity and the prevalence of cardiometabolic risk factors in apparently healthy, non-obese adolescents even within the range of normal laboratory and anthropomorphic values and suggest that iron stores should be investigated as a potentially modifiable risk factor in healthy teenagers.
Subject(s)
Cardiovascular Diseases/physiopathology , Ferritins/analysis , Iron/blood , Metabolic Syndrome/physiopathology , Transaminases/blood , Adolescent , Blood Glucose/analysis , Blood Pressure , Body Mass Index , Female , Humans , Insulin/blood , Lipids/blood , Liver/diagnostic imaging , Male , Regression Analysis , Risk Factors , Ultrasonography , Waist-Hip RatioABSTRACT
The advantages of systems with Ag nanoparticles and their assemblies for surface-enhanced resonance Raman scattering (SERRS) spectral investigation, detection and determination of porphyrin species are demonstrated. SERRS spectral detection limits of the testing porphyrin species (including porphyrin aggregates) in these systems are shown to be, on average, 10(2)-10(3) lower than detection limits by resonance Raman scattering (RRS). Systems with Ag nanoparticles modified by anionic organosulfur spacers enable us to obtain SERRS spectra of unperturbed cationic porphyrin species. In the case of thiopheneacetate-modified Ag particles prepared by laser ablation, no negative effect of the spacer on the spectral detection limit of the porphyrin was observed. Systems with isolated Ag nanoparticles allow for obtaining SERRS spectra of porphyrin species upon excitation into the Soret electronic absorption band which leads to at least a 10-fold decrease in the detection limit.