Role of adiponectin in human skeletal muscle bioenergetics.

Insulin resistance is associated with impaired skeletal muscle oxidation capacity and reduced mitochondrial number and function. Here, we report that adiponectin signaling regulates mitochondrial bioenergetics in skeletal muscle. Individuals with a family history of type 2 diabetes display skeletal muscle insulin resistance and mitochondrial dysfunction; adiponectin levels strongly correlate with mtDNA content. Knockout of the adiponectin gene in mice is associated with insulin resistance and low mitochondrial content and reduced mitochondrial enzyme activity in skeletal muscle. Adiponectin treatment of human myotubes in primary culture induces mitochondrial biogenesis, palmitate oxidation, and citrate synthase activity, and reduces the production of reactive oxygen species. The inhibition of adiponectin receptor expression by siRNA, or of AMPK by a pharmacological agent, blunts adiponectin induction of mitochondrial function. Our findings define a skeletal muscle pathway by which adiponectin increases mitochondrial number and function and exerts antidiabetic effects.

Isolation of human adipose-derived stem cells from biopsies and liposuction specimens.

Adipose tissue has proven to serve as an abundant, accessible, and rich source of adult stem cells with multipotent properties suitable for tissue engineering and regenerative medical applications. Here, we describe a detailed method for the isolation and expansion of adipose-derived stem cells (ASCs). We present a large scale procedure suitable for processing >100 mL volumes of lipoaspirate tissue specimens and a small scale procedure suitable for processing adipose tissue biopsy specimens of < 0.5 g. Although we have focused on the isolation of ASCs from human adipose tissue, the procedure can be applied to adipose tissues from other species with minimal modifications.

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.

Breastfeeding duration and weight gain trajectory in infancy.

BACKGROUND AND OBJECTIVES: Short breastfeeding duration may exacerbate accelerated early growth, which is linked to higher obesity risk in later life. This study tested the hypothesis that infants at higher risk for obesity were more likely to be members of a rising weight-for-length (WFL) z score trajectory if breastfed for shorter durations. METHODS: This prospective, observational study recruited women from an obstetric patient population in rural central New York. Medical records of children born to women in the cohort were audited for weight and length measurements (n = 595). We identified weight gain trajectories for infants' WFL z scores from 0 to 24 months by using maximum likelihood latent class models. Individual risk factors associated with weight gain trajectories (P ≤ .05) were included in an obesity risk index. Logistic regression analysis was performed to investigate whether the association between breastfeeding duration (<2 months, 2-4 months, >4 months) and weight gain trajectory varied across obesity risk groups. RESULTS: Rising and stable weight gain trajectories emerged. The obesity risk index included maternal BMI, education, and smoking during pregnancy. High-risk infants breastfed for <2 months were more likely to belong to a rising rather than stable weight gain trajectory (odds ratio, 2.55; 95% confidence interval, 1.14-5.72; P = .02). CONCLUSIONS: Infants at the highest risk for rising weight patterns appear to benefit the most from longer breastfeeding duration. Targeting mothers of high-risk infants for breastfeeding promotion and support may be protective against overweight and obesity during a critical window of development.

Associations Between Mothers' and Their Children's Weights at 4 Years of Age.

OBJECTIVES: To examine the importance of maternal weight characteristics as predictors of overweight (BMI ≥85th percentile and <95th percentile) and obesity (BMI ≥ 95th percentile) in offspring at age 4 years. METHODS: Chi-square and logistic regression analyses were conducted on a sample of 321 mother/child pairs from an earlier observational cohort study on mothers' postpartum weight retention. RESULTS: Maternal early pregnancy BMI and infant birth weight were each positively and significantly (p <0.05) associated with increased risk of obesity in offspring at age 4 years. A significant interaction was found between these two variables in predicting children's risk of obesity. It was driven by the high proportion of obese children among obese women who had infants weighing < 3 kg at birth. Net gestational weight gain was not associated with obesity risk in children, but was positively associated with infant birth weight among normal weight and overweight women. CONCLUSIONS: Reducing maternal BMI in the preconception period among overweight and obese women and preventing excessive weight gain in pregnancy for all women appear to be appropriate strategies to address the childhood obesity epidemic.

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 PGC1alpha 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.

Cellular localization and function of the antiviral protein, ovine Mx1 (oMx1): I. Ovine Mx1 is secreted by endometrial epithelial cells via an 'unconventional' secretory pathway.

PROBLEM: Embryonic loss is a major contributor to infertility. Understanding factors contributing to embryonic loss will aid in development of technologies to improve/regulate fertility in animals and humans. METHOD OF STUDY: We tested the hypothesis that the antiviral protein, ovine Mx1 (oMx1), is secreted by uterine epithelial cells. Uterine flushes were obtained from cyclic and early pregnant ewes and examined for levels of oMx1 protein. The pathway for ovine Mx1 secretion in ovine glandular epithelial (oGE) cells was determined using brefeldin A (BFA), an inhibitor of the conventional secretory pathway. Effects of BFA were determined using beta2-microglobulin (beta2MG) as a marker for the conventional secretory pathway, and interferon stimulated gene 15 (ISG15) and Galectin-1 (Gal-1) as markers for the unconventional secretory pathways. RESULTS: Ovine Mx1 protein levels were low in uterine flushes from cyclic ewes and levels increased in pregnant ewes after D 15. Ovine GE cells secreted oMx1 in response to interferon and secretion was not reduced by BFA, suggesting oMx1 was secreted via an unconventional secretory pathway. beta2MG secretion was reduced by BFA, whereas ISG15 and Gal-1 were not. CONCLUSION: This is the first report that the antiviral protein, oMx1, is secreted and provides evidence that secretion occurs via unconventional secretory pathway(s).