Exercise-induced mitochondrial p53 repairs mtDNA mutations in mutator mice.

Background: Human genetic disorders and transgenic mouse models have shown that mitochondrial DNA (mtDNA) mutations and telomere dysfunction instigate the aging process. Epidemiologically, exercise is associated with greater life expectancy and reduced risk of chronic diseases. While the beneficial effects of exercise are well established, the molecular mechanisms instigating these observations remain unclear.

Effects of age and unaccustomed resistance exercise on mitochondrial transcript and protein abundance in skeletal muscle of men.

Mitochondrial dysfunction may contribute to age-associated muscle atrophy. Previous data has shown that resistance exercise (RE) increases mitochondrial gene expression and enzyme activity in older adults; however, the acute response to RE has not been well characterized. To characterize the acute mitochondrial response to unaccustomed RE, healthy young (21 ± 3 yr) and older (70 ± 4 yr) men performed a unilateral RE bout for the knee extensors.

The unfolded protein response is triggered following a single, unaccustomed resistance-exercise bout.

Endoplasmic reticulum (ER) stress results from an imbalance between the abundance of synthesized proteins and the folding capacity of the ER. In response, the unfolded protein response (UPR) attempts to restore ER function by attenuating protein synthesis and inducing chaperone expression. Resistance exercise (RE) stimulates protein synthesis; however, a postexercise accumulation of unfolded proteins may activate the UPR.

Elevated mitochondrial oxidative stress impairs metabolic adaptations to exercise in skeletal muscle.

Mitochondrial oxidative stress is a complex phenomenon that is inherently tied to energy provision and is implicated in many metabolic disorders. Exercise training increases mitochondrial oxidative capacity in skeletal muscle yet it remains unclear if oxidative stress plays a role in regulating these adaptations. We demonstrate that the chronic elevation in mitochondrial oxidative stress present in Sod2 (+/-) mice impairs the functional and biochemical mitochondrial adaptations to exercise.

Oxidative stress and Nrf2 signaling in McArdle disease.

McArdle disease (MD) is a metabolic myopathy due to myophosphorylase deficiency, which leads to a severe limitation in the rate of adenosine triphosphate (ATP) resynthesis. Compensatory flux through the myoadenylate deaminase > > xanthine oxidase pathway should result in higher oxidative stress in skeletal muscle; however, oxidative stress and nuclear factor erythroid 2-related factor 2 (Nrf2) mediated antioxidant response cascade in MD patients have not yet been examined. We show that MD patients have elevated muscle protein carbonyls and 4-hydroxynonenal (4-HNE) in comparison with healthy, age and activity matched controls (P < 0.

Supplementation with α-lipoic acid, CoQ10, and vitamin E augments running performance and mitochondrial function in female mice.

Antioxidant supplements are widely consumed by the general public; however, their effects of on exercise performance are controversial. The aim of this study was to examine the effects of an antioxidant cocktail (α-lipoic acid, vitamin E and coenzyme Q10) on exercise performance, muscle function and training adaptations in mice. C57Bl/J6 mice were placed on antioxidant supplement or placebo-control diets (n = 36/group) and divided into trained (8 wks treadmill running) (n = 12/group) and untrained groups (n = 24/group).

Monocarboxylate transporters and mitochondrial creatine kinase protein content in McArdle disease.

McArdle disease (MD) is a metabolic myopathy due to myophosphorylase deficiency. We examined monocarboxylate transporters (MCT) and creatine kinase (CK) protein content in skeletal muscle from MD patients and age-matched controls to evaluate potential cellular adaptations that compensate for the loss of glycogenolysis. Our findings of higher MCT1 and mitochondrial CK suggest that proteins related to extra-muscular fuel uptake and intra-muscular energy transduction are up-regulated without change in mitochondrial mass in MD patients.

Elevated SOCS3 and altered IL-6 signaling is associated with age-related human muscle stem cell dysfunction.

Aging is associated with increased circulating interleukin-6 (IL-6) and a reduced myogenic capacity, marked by reduced muscle stem cell [satellite cell (SC)] activity. Although IL-6 is important for normal SC function, it is unclear whether elevated IL-6 associated with aging alters SC function. We hypothesized that mild chronically elevated IL-6 would be associated with a blunted SC response through altered IL-6 signaling and elevated suppressor of cytokine signaling-3 (SOCS3) in the elderly.

Myostatin is associated with age-related human muscle stem cell dysfunction.

Human aging is accompanied by a progressive loss of muscle mass (sarcopenia). We tested the hypothesis that older males (OMs, 70±4 yr, n=9) would have a blunted myogenic response to a physiological stimulus compared to younger controls (21±3 yr, n=9). Subjects completed an acute bout of intense unilateral muscle loading.

Effects of creatine and exercise on skeletal muscle of FRG1-transgenic mice.

Background: The FRG1-transgenic mouse displays muscle dysfunction and atrophy reminiscent of fascioscapulohumeral muscular dystrophy (FSHD) and could provide a model to determine potential therapeutic interventions.

Methods: To determine if FRG1 mice benefit from treatments that improve muscle mass and function, mice were treated with creatine alone (Cr) or in combination with treadmill exercise (CrEX).

Results: The CrEx treatment increased quadriceps weight, mitochondrial content (cytochome c oxidase (COX) activity, COX subunit one and four protein), and induced greater improvements in grip strength and rotarod fall speed.

Massage therapy attenuates inflammatory signaling after exercise-induced muscle damage.

Massage therapy is commonly used during physical rehabilitation of skeletal muscle to ameliorate pain and promote recovery from injury. Although there is evidence that massage may relieve pain in injured muscle, how massage affects cellular function remains unknown. To assess the effects of massage, we administered either massage therapy or no treatment to separate quadriceps of 11 young male participants after exercise-induced muscle damage.

Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice.

A causal role for mitochondrial DNA (mtDNA) mutagenesis in mammalian aging is supported by recent studies demonstrating that the mtDNA mutator mouse, harboring a defect in the proofreading-exonuclease activity of mitochondrial polymerase gamma, exhibits accelerated aging phenotypes characteristic of human aging, systemic mitochondrial dysfunction, multisystem pathology, and reduced lifespan. Epidemiologic studies in humans have demonstrated that endurance training reduces the risk of chronic diseases and extends life expectancy. Whether endurance exercise can attenuate the cumulative systemic decline observed in aging remains elusive.

Effects of exercise and muscle type on BDNF, NT-4/5, and TrKB expression in skeletal muscle.

Muscle-derived neurotrophins are thought to contribute to the adaptation of skeletal muscle to exercise, but the effects of brief exercise interventions on BDNF, NT-4/5, and trkB are not understood. RNA was extracted for RT-PCR from soleus and medial gastrocnemius of Sprague-Dawley rats exercised on a treadmill at speeds up to 20 m/min at 5% incline for 5 or 10 days. BDNF expression was elevated in soleus following 5 days (184%, P < 0.