Branched Chain and Aromatic Amino Acids Are Associated With Insulin Resistance During Pubertal Development in Girls

IGF-I deficiency and enhanced insulin sensitivity due to a mutated growth hormone receptor gene in humans

Human size is achieved by the coordinated expression of many genes. From conception to adulthood, a given genomic endowment is modified by highly variable environmental circumstances. During each stage of a person's life, distinct nutritional and hormonal influences continuously shape growing physical features until mature characteristics are attained. Underlying processes depend on precise provision of substrates and energy extracted by insulin action from nutrients, which allows cell proliferation, differentiation, and survival, under the concerted actions of growth hormone and insulin-like growth factor-I (IGF-I). It should be noted that growth and metabolic signaling pathways are interdependent and superimposed at multiple levels. Attainment of a fully developed human phenotype should be considered as a harmonious increment in body size rather than a simple increase in height. From this perspective we herein analyze adult features of individuals with an inactive growth hormone receptor, who consequently have severely diminished concentrations of serum insulin and endocrine IGF-I.

miR-26a Attenuated Bone-Specific Insulin Resistance and Bone Quality in Diabetic Mice

Diabetes mellitus is a prevalent disease result in several complications, including bone problems. Previous studies have shown that microRNA (miR)-26a regulates glucose metabolism and plays a protective role in diabetes. However, whether miR-26a also affects bone quality in diabetes remains unknown. In the present study, we evaluated the potential effects of miR-26a on bone in diabetic mice. We administrated miR-26a in streptozotocin-induced diabetic mice. The metabolic parameters, bone quality, osteoblast and osteoclast markers, and insulin signaling activation were measured. miR-26a ameliorated insulin resistance and glucose tolerance, improved bone microarchitecture and quality, increased osteoblasts and bone formation, decreased osteoclasts, and promoted the insulin signaling pathway in diabetic mice. These effects were abolished in insulin receptor-compromised Col1a1-Insr^+/- mice. In conclusion, miR-26a could ameliorate bone-specific insulin resistance and bone quality in diabetic mice, which depended on the insulin receptors on osteoblasts. Our findings highlight the potential of miR-26a as a therapeutic target for diabetes mellitus-related bone metabolism and diseases.

Animal Protein Intake Is Associated with General Adiposity in Adolescents: The Teen Food and Development Study

Protein plays a crucial role in the growth and development of adolescents. However, being a secondary energy source, protein's role in obesity has been sidelined. We examined whether intake of protein (total, animal, plant), branched-chain (BCAAs), and sulfur-containing (SCAAs) amino acids are associated with general body and central obesity and body composition in a cross-sectional study among healthy adolescents. Students aged 12-18 years old (n = 601) in schools near two major Adventist universities in California and Michigan provided dietary data via a validated web-based food frequency questionnaire (FFQ) and anthropometric data during school visits. Intakes of total, animal, and plant proteins, and BCAAs and SCAAs were derived from FFQ data. We defined general body obesity with body-mass-index-for-age (BMIz) z-scores and central obesity with waist-to-height ratios (WHtR). After full adjustment for covariates, multiple regression analyses showed significant positive associations between intakes of total protein (β = 0.101, 95% CI: 0.041, 0.161), animal protein (β = 0.118, 95% CI: 0.057, 0.178), BCAAs (β = 0.056, 95% CI: 0.025, 0.087), and SCAAs (β = 0.025, 95% CI: 0.012, 0.038) with general body adiposity. Animal protein (β = 0.017, 95% CI: 0.001, 0.033) and SCAAs (β = 0.004, 95% CI: 0.000, 0.008) were also associated with central obesity. Total and animal protein and BCAA and SCAA were also significantly associated with fat mass. Our findings suggest that high protein intake may pose a possible detriment to adolescent health. Longitudinal and safety evaluation studies are recommended.