Role of oxidation of excitation-contraction coupling machinery in age-dependent loss of muscle function in .

Age-dependent loss of body wall muscle function and impaired locomotion occur within 2 weeks in ; however, the underlying mechanism has not been fully elucidated. In humans, age-dependent loss of muscle function occurs at about 80 years of age and has been linked to dysfunction of ryanodine receptor (RyR)/intracellular calcium (Ca) release channels on the sarcoplasmic reticulum (SR). Mammalian skeletal muscle RyR1 channels undergo age-related remodeling due to oxidative overload, leading to loss of the stabilizing subunit calstabin1 (FKBP12) from the channel macromolecular complex.

Excess TGF-β mediates muscle weakness associated with bone metastases in mice.

Cancer-associated muscle weakness is a poorly understood phenomenon, and there is no effective treatment. Here we find that seven different mouse models of human osteolytic bone metastases-representing breast, lung and prostate cancers, as well as multiple myeloma-exhibited impaired muscle function, implicating a role for the tumor-bone microenvironment in cancer-associated muscle weakness. We found that transforming growth factor (TGF)-β, released from the bone surface as a result of metastasis-induced bone destruction, upregulated NADPH oxidase 4 (Nox4), resulting in elevated oxidization of skeletal muscle proteins, including the ryanodine receptor and calcium (Ca(2+)) release channel (RyR1).

[THE ENERGY FUNCTION OF RAT CARDIAC MITOCHONDRIA UNDER ARTIFICIAL HYPOBIOSIS].

We investigated the energy activity of mitochondria from rat cardiomyocytes under the artificial carbon dioxide hypobiosis, which led to physiological changes in the organism (the decrease of body temperature, the reduction of heart rate, etc.). The respiratory and phosphorylation activities in mitochondria of cardiomyocytes is reduced when using two oxidation substrates (succinate and malate), which characterize the rate of the oxygen consumption by the mitochondria.

Genetically enhancing mitochondrial antioxidant activity improves muscle function in aging.

Age-related skeletal muscle dysfunction is a leading cause of morbidity that affects up to half the population aged 80 or greater. Here we tested the effects of increased mitochondrial antioxidant activity on age-dependent skeletal muscle dysfunction using transgenic mice with targeted overexpression of the human catalase gene to mitochondria (MCat mice). Aged MCat mice exhibited improved voluntary exercise, increased skeletal muscle specific force and tetanic Ca(2+) transients, decreased intracellular Ca(2+) leak and increased sarcoplasmic reticulum (SR) Ca(2+) load compared with age-matched wild type (WT) littermates.

Stress-induced increase in skeletal muscle force requires protein kinase A phosphorylation of the ryanodine receptor.

Enhancement of contractile force (inotropy) occurs in skeletal muscle following neuroendocrine release of catecholamines and activation of muscle β-adrenergic receptors. Despite extensive study, the molecular mechanism underlying the inotropic response in skeletal muscle is not well understood. Here we show that phosphorylation of a single serine residue (S2844) in the sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor type 1 (RyR1) by protein kinase A (PKA) is critical for skeletal muscle inotropy.

Leaky ryanodine receptors in β-sarcoglycan deficient mice: a potential common defect in muscular dystrophy.

Background: Disruption of the sarcolemma-associated dystrophin-glycoprotein complex underlies multiple forms of muscular dystrophy, including Duchenne muscular dystrophy and sarcoglycanopathies. A hallmark of these disorders is muscle weakness. In a murine model of Duchenne muscular dystrophy, mdx mice, cysteine-nitrosylation of the calcium release channel/ryanodine receptor type 1 (RyR1) on the skeletal muscle sarcoplasmic reticulum causes depletion of the stabilizing subunit calstabin1 (FKBP12) from the RyR1 macromolecular complex.

Ryanodine receptor oxidation causes intracellular calcium leak and muscle weakness in aging.

Age-related loss of muscle mass and force (sarcopenia) contributes to disability and increased mortality. Ryanodine receptor 1 (RyR1) is the skeletal muscle sarcoplasmic reticulum calcium release channel required for muscle contraction. RyR1 from aged (24 months) rodents was oxidized, cysteine-nitrosylated, and depleted of the channel-stabilizing subunit calstabin1, compared to RyR1 from younger (3-6 months) adults.

Zebrafish RNase T2 genes and the evolution of secretory ribonucleases in animals.

Background: Members of the Ribonuclease (RNase) T2 family are common models for enzymological studies, and their evolution has been well characterized in plants. This family of acidic RNases is widespread, with members in almost all organisms including plants, animals, fungi, bacteria and even some viruses. While several biological functions have been proposed for these enzymes in plants, their role in animals is unknown.