Calorie Restriction Increases Muscle Mitochondrial Biogenesis in Healthy Humans

BACKGROUND: Caloric restriction without malnutrition extends life span in a range of organisms including insects and mammals and lowers free radical production by the mitochondria. However, the mechanism responsible for this adaptation are poorly understood. METHODS AND FINDINGS: The current study was undertaken to examine muscle mitochondrial bioenergetics in response to caloric restriction alone or in combination with exercise in 36 young (36.8 ± 1.0 y), overweight (body mass index, 27.8 ± 0.7 kg/m(2)) individuals randomized into one of three groups for a 6-mo intervention: Control, 100% of energy requirements; CR, 25% caloric restriction; and CREX, caloric restriction with exercise (CREX), 12.5% CR + 12.5% increased energy expenditure (EE). In the controls, 24-h EE was unchanged, but in CR and CREX it was significantly reduced from baseline even after adjustment for the loss of metabolic mass (CR, −135 ± 42 kcal/d, p = 0.002 and CREX, −117 ± 52 kcal/d, p = 0.008). Participants in the CR and CREX groups had increased expression of genes encoding proteins involved in mitochondrial function such as PPARGC1A, TFAM, eNOS, SIRT1, and PARL (all, p < 0.05). In parallel, mitochondrial DNA content increased by 35% ± 5% in the CR group (p = 0.005) and 21% ± 4% in the CREX group (p < 0.004), with no change in the control group (2% ± 2%). However, the activity of key mitochondrial enzymes of the TCA (tricarboxylic acid) cycle (citrate synthase), beta-oxidation (beta-hydroxyacyl-CoA dehydrogenase), and electron transport chain (cytochrome C oxidase II) was unchanged. DNA damage was reduced from baseline in the CR (−0.56 ± 0.11 arbitrary units, p = 0.003) and CREX (−0.45 ± 0.12 arbitrary units, p = 0.011), but not in the controls. In primary cultures of human myotubes, a nitric oxide donor (mimicking eNOS signaling) induced mitochondrial biogenesis but failed to induce SIRT1 protein expression, suggesting that additional factors may regulate SIRT1 content during CR. CONCLUSIONS: The observed increase in muscle mitochondrial DNA in association with a decrease in whole body oxygen consumption and DNA damage suggests that caloric restriction improves mitochondrial function in young non-obese adults

Regulation of skeletal muscle oxidative capacity and insulin signaling by the Mitochondrial Rhomboid Protease PARL

Type 2 diabetes mellitus (T2DM) and aging are characterized by insulin resistance and impaired mitochondrial energetics. In lower organisms, remodeling by the protease pcp1 (PARL ortholog) maintains the function and lifecycle of mitochondria. We examined whether variation in PARL protein content is associated with mitochondrial abnormalities and insulin resistance. PARL mRNA and mitochondrial mass were both reduced in elderly subjects and in subjects with T2DM. Muscle knockdown of PARL in mice resulted in malformed mitochondrial cristae, lower mitochondrial content, decreased PGC1&alpha; protein levels, and impaired insulin signaling. Suppression of PARL protein in healthy myotubes lowered mitochondrial mass and insulin-stimulated glycogen synthesis and increased reactive oxygen species production. We propose that lower PARL expression may contribute to the mitochondrial abnormalities seen in aging and T2DM.<br /

Maternal Experiences Associated With Optimal Breastfeeding Behavior And The Role Of Breastfeeding In Moderating Child Risk Of Obesity

Background While clearly beneficial, some women do not engage in optimal breastfeeding practices. In addition, the impact of breastfeeding on early obesity development is unclear. The purpose of this research was to gain new insights regarding maternal barriers to exclusive breastfeeding behavior using an innovative mixed methods approach, and to investigate the impact of breastfeeding on infant-weight gain trajectories. Methods Longitudinal data from rural, central New York (N=595), spanning pregnancy through 2 years postpartum were used in this research. Data collection involved medical record audits and mailed survey questionnaires. Analytic methods included writing, coding and interpreting biographies built from survey data, building infant weight-gain trajectories using latent-class modeling techniques, and performing multivariate logistic regression procedures to assess odds of exclusively breastfeeding for 4 months and odds of membership in rising WFL z-score trajectories. Results Exclusive breastfeeding for 4 months was more likely to occur in women who were older, higher income, more flexible, more determined and driven, had more social support, lower early pregnancy BMI, and/or intended to exclusively breastfeed. ! The odds of exclusively breastfeeding for 4 months were higher in women who were older, less career-oriented, and intended to exclusively breastfeed. For less educated women, those with a lower external locus of control were more likely to exclusively breastfeed than those with a higher external locus of control. Children with a rising weight-gain trajectory were more likely to have mothers who were obese in early pregnancy, had a high school education or less, and smoked during pregnancy. In addition, children whose mothers exhibited at least two of these characteristics were more likely to have a rising weight-gain trajectory if they breastfed for less than 2 months when compared to children who breastfed for more than 4 months. Conclusions Breastfeeding occurs during a critical window of child development when infants may be more susceptible to the effects of maternal risk factors for child obesity. Understanding population-specific barriers to optimal breastfeeding behavior is critical, particularly in high-risk populations, for the development of appropriate interventions. Evidence shows longer breastfeeding duration may be protective against accelerated infant growth that increases the risk of future overweight and obesity.

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Abstract As modern genomic tools are developed for ecologically compelling models, field manipulation experiments will become important for establishing the role of functional genomic variation in physiological acclimation and evolutionary adaptation along environmental clines. High-altitude habitats expose individuals to hypoxic and thermal stress, necessitating physiological acclimation, which may result in evolutionary adaptation. We assayed skeletal muscle transcriptomic profiles of rufous-collared sparrows (Zonotrichia capensis) distributed along an altitudinal gradient on the Pacific slope of the Peruvian Andes. Nearly 200 unique transcripts were differentially expressed between high-altitude [4100 m above sea level (a.s.l.)] and low-altitude (2000 m a.s.l.) populations in their native habitats. Gene ontology and network analyses revealed that these transcripts are primarily involved in oxidative phosphorylation, protein biosynthesis, signal transduction and oxidative stress response pathways. To assess the plasticity in gene expression differences between populations, we performed a &apos;common garden&apos; experiment in which high-and low-altitude individuals were transferred to a common low-altitude site (~150 m). None of the genes that were differentially expressed between populations at the native altitudes remained significantly different between populations in the common garden. The role of gene expression variation in adaptation and acclimation to environmental stress is largely unexplored in natural populations of birds. These results demonstrate substantial plasticity in the biochemical pathways that underpin cold and hypoxia compensation in Z. capensis, which may mechanistically contribute to enabling the broad altitudinal distribution of the species

Statistical Dot Plots Showing the Effects of DETA-NO and Adiponectin Treatment on Mitochondrial Content and SIRT1 Protein in Primary Human Myotubes

<div><p>(A–C) Effects of 96 h of 50 μM DETA-NO treatment on mitochondrial content (using MitoTracker Green, <i>p</i> = 0.002) (A), electron transport chain activity (COX, <i>p</i> = 0.018) (B), and mitochondrial membrane potential (TMRE, <i>n</i> = 6, <i>p</i> = 0.042) (C). Treatment effect was determined using independent sample t-test. OD, optical density.</p> <p>(D) Effects of 50 μM DETA-NO on SIRT1 and β-actin protein (top blots); effects of 0.5 μg/ml of globular adiponectin (gAD) and adiponectin receptor R1- and R2-siRNA on SIRT1 and β-actin protein expression (bottom blots). Immunoblotting was undertaken in three participants and data are shown as a representative blot. Means are denoted by the solid black bars.</p></div

The Effects of Caloric Restriction on Mitochondrial Bionenergetics

<p>(A and B) Each box plot shows the distribution of expression levels from 25th to 75th percentile and the lines inside the boxes denote the medians. The whiskers denote the interval between the 10th and 90th percentiles. The filled circles mark the data points outside the 10th and 90th percentiles. (A) Caloric deficit–induced mitochondrial biogenesis in the CR group (35% ± 5%, ^*<i>p</i> = 0.005) and the CREX group (21% ± 4%, ^#<i>p</i> < 0.004), with no change in the control group (2% ± 2%). The y-axis represents the relative change from baseline in mtDNA for each study group. (B) Analysis of mitochondrial enzyme activity; β-HAD (β-oxidation); CS (TCA cycle), and COX (electron transport chain). The y-axis represents the relative change from baseline in mitochondrial enzyme activity for each study group. (C) Linear correlation between the change from baseline in <i>SIRT1</i> and <i>PPARGC1A</i> mRNAs from baseline in control (○), <i>r</i> = 0.83, <i>p</i> < 0.05; CR (□), <i>r</i> = 0.95, <i>p</i> < 0.01; and CREX participants (▵), <i>r</i> = 0.76, <i>p</i> < 0.05). The linear correlation between the change in <i>SIRT1</i> mRNA and <i>PPARGC1A</i> mRNA from baseline in the CR group (□) remained significant after exclusion of the outlier (<i>r</i> = 0.81, <i>p</i> < 0.01). Changes from baseline to month 6 were analyzed by analysis of variance with baseline values included as covariates.</p

Changes in Skeletal Muscle Gene Expression for Key Mitochondrial Proteins

<div><p>(A) TFAM: ^*CR, <i>p</i> = 0.001; ^#CREX, <i>p</i> = 0.014.</p> <p>(B) PPARGC1A: ^*CR, <i>p</i> = 0.004; ^#CREX, <i>p</i> = 0.002.</p> <p>(C) SIRT1: ^*CR, <i>p</i> = 0.016; ^#CREX, <i>p</i> = 0.023.</p> <p>(D) eNOS: ^*CR, <i>p</i> = 0.002; ^#CREX, <i>p</i> = 0.039.</p> <p>Graphs show six-month changes in enzyme expression in response to each intervention. The y-axis represents the relative gene expression change from baseline for each study group. Each box plot shows the distribution of expression levels from 25th to 75th percentile, and the lines inside the boxes denote the medians. The whiskers denote the interval between the 10th and 90th percentiles. The filled circles mark the data points outside the 10th and 90th percentiles. Molecular analysis was performed in 11 of 12 volunteers per group from whom there was sufficient pre- and postintervention sample for this determination. Changes from baseline to month 6 were analyzed by analysis of variance with baseline values included as covariates.</p></div