In the present study we have compared the effects of leucine supplementation and its metabolite β-hydroxy-β-methyl butyrate (HMB) on the ubiquitin-proteasome system and the PI3K/Akt pathway during two distinct atrophic conditions, hindlimb immobilization and dexamethasone treatment. Leucine supplementation was able to minimize the reduction in rat soleus mass driven by immobilization. On the ot...

Skeletal muscle is the largest pool of protein in the body. Maintenance of its mass involves a delicate balance between protein synthesis and degradation. The dynamic nature of muscle is evident when one considers that healthy adults turn over 3.5–4.5 g of protein/kg d—stated another way, an average individual synthesizes and degrades approximately 1.0–1.5 kg protein per day (1). Therefore, a s...

Resistance exercise and amino acids are two major factors that influence muscle protein turnover. Here, we examined the effects of resistance exercise and branched-chain amino acids (BCAA), individually and in combination, on the expression of anabolic and catabolic genes in human skeletal muscle. Seven subjects performed two sessions of unilateral leg press exercise with randomized supplementa...

Hormone replacement therapy (HRT) is used in postmenopausal women to relieve symptoms of menopause and prevent osteoporosis. We sought to evaluate changes in mRNA expression of key myogenic factors in postmenopausal women taking and not taking HRT following a high-intensity eccentric resistance exercise. Fourteen postmenopausal women were studied and included 6 control women not using HRT (59 +...

Previously, we reported that mitogen-activated protein kinase kinase 1 (MEK1) activated in the mid-stage of skeletal muscle differentiation promotes myogenic differentiation. To elucidate the molecular mechanism, we investigated an activity of MEK1 for MyoD. Activated MEK1 associates with MyoD in the nucleus of differentiating myoblasts. In vitro kinase assay using active MEK1, a (32)P-labeled ...

Chronic arthritis is a catabolic state associated with an inhibition of the IGF system and a decrease in body weight. Cachexia and muscular wasting is secondary to protein degradation by the ubiquitin-proteasome pathway. The aim of this work was to analyze the effect of adjuvant-induced arthritis on the muscle-specific ubiquitin ligases muscle ring finger 1 (MuRF1) and muscle atrophy F-box (MAF...

BACKGROUND Porcine congenital splayleg (PCS) is the most important congenital condition of piglets, associated with lameness and immobility, of unknown aetiology and pathogenesis, hence the need to better understand the condition by defining, in the first instance, its histopathology and molecular pathology. RESULTS Semitendinosus, longissimus dorsi, and gastrocnemius muscles were removed fro...

Forkhead box O (Foxo) transcription factors induce muscle atrophy by upregulating the muscle-specific E3 ubiquitin ligases MuRF-1 and atrogin-1/MAFbx, but other than Akt, the upstream regulators of Foxos during muscle atrophy are largely unknown. To examine the involvement of the dystrophin glycoprotein complex (DGC) in regulation of Foxo activities and muscle atrophy, we analyzed the expressio...