cyclic-gmp and Muscular-Dystrophies

Satellite cells are myogenic precursors that proliferate, activate, and differentiate on muscle injury to sustain the regenerative capacity of adult skeletal muscle; in this process, they self-renew through the return to quiescence of the cycling progeny. This mechanism, while efficient in physiological conditions does not prevent exhaustion of satellite cells in pathologies such as muscular dystrophy where numerous rounds of damage occur. Here, we describe a key role of nitric oxide, an important signaling molecule in adult skeletal muscle, on satellite cells maintenance, studied ex vivo on isolated myofibers and in vivo using the α-sarcoglycan null mouse model of dystrophy and a cardiotoxin-induced model of repetitive damage. Nitric oxide stimulated satellite cells proliferation in a pathway dependent on cGMP generation. Furthermore, it increased the number of Pax7(+)/Myf5(-) cells in a cGMP-independent pathway requiring enhanced expression of Vangl2, a member of the planar cell polarity pathway involved in the Wnt noncanonical pathway. The enhanced self-renewal ability of satellite cells induced by nitric oxide is sufficient to delay the reduction of the satellite cell pool during repetitive acute and chronic damages, favoring muscle regeneration; in the α-sarcoglycan null dystrophic mouse, it also slowed disease progression persistently. These results identify nitric oxide as a key messenger in satellite cells maintenance, expand the significance of the Vangl2-dependent Wnt noncanonical pathway in myogenesis, and indicate novel strategies to optimize nitric oxide-based therapies for muscular dystrophy.

Topics: Animals; Cell Differentiation; Cell Proliferation; Cells, Cultured; Cyclic GMP; Female; Gene Expression Regulation; Mice; Mice, 129 Strain; Molsidomine; Muscle Development; Muscle, Skeletal; Muscular Dystrophies; Nerve Tissue Proteins; Nitric Oxide; Nitric Oxide Donors; Regeneration; Satellite Cells, Skeletal Muscle; Signal Transduction

Nitric oxide generated by neuronal nitric oxide synthase in contracting skeletal muscle fibers may regulate vascular relaxation via a cGMP-mediated pathway. Neuronal nitric oxide synthase content is greatly reduced in skeletal muscles from mdx mice. cGMP formation increased in contracting extensor digitorum longus muscles in vitro from C57 control, but not mdx mice. The increase in cGMP content was abolished with NG-nitro-L-arginine. Sodium nitroprusside treatment increased cGMP levels in muscles from both C57 and mdx mice. Skeletal muscle contractions also inhibited phenylephrine-induced phosphorylation of smooth muscle myosin regulatory light chain. Arteriolar dilation was attenuated in contracting muscles from mdx but not C57 mice. NO generated in contracting skeletal muscle may contribute to vasodilation in response to exercise.

Topics: Animals; Cyclic GMP; Humans; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Muscle Contraction; Muscle, Skeletal; Muscle, Smooth, Vascular; Muscular Dystrophies; Myosin Light Chains; Myosins; Nitric Oxide; Phosphorylation; Physical Exertion; Vasodilation

Recently, a significant activity of inducible nitric oxide synthase (iNOS) has been reported in biopsies from failing hearts due to idiopathic dilated cardiomyopathy (IDC). Thus, a potential pathophysiological role of iNOS in IDC has been stated. In order to investigate, whether iNOS expression is of pathophysiological relevance in human heart failure, we measured iNOS protein expression and cGMP content in left ventricular myocardium from non-failing and failing human hearts. Immunoblot analysis revealed iNOS protein expression in four out of six failing hearts from septic patients, whereas no iNOS-protein expression was detected in either non-failing human hearts (n = 6) or failing hearts due to IDC (n = 9), ischemic heart disease (IHD, n = 7), Becker muscular dystrophy (BMD, n = 2) and mitoxantrone-induced toxic cardiomyopathy TCM, n = 1). cGMP content was increased by 130% in septic hearts, whereas there was no cGMP increase in hearts with IDC. IHD and BMD compared to non-failing hearts. We conclude, that the induction of iNOS may play a role in contractile dysfunction observed in septic shock, but is unlikely to be of major pathophysiological importance in end-stage heart failure due to IDC, IHD, BMD and TCM.

Topics: Animals; Cardiomyopathies; Cardiomyopathy, Dilated; Cell Line; Cyclic GMP; Gene Expression; Heart Failure; Heart Ventricles; Humans; Isoenzymes; Macrophages; Mice; Mitoxantrone; Muscular Dystrophies; Myocardial Ischemia; Myocardium; Nitric Oxide Synthase; Reference Values; Sepsis

The properties and distribution of basal and cyclic nucleotide stimulated protein kinases have been studied in normal and diseased human muscles. In particulate fraction of muscles from neurogenic atrophy the PK activity is remarkably lower than in control tissues, whereas in the cytosol of the same tissues an increase of enzyme activity was observed. In Duchenne dystrophy the PK activities were slighly lower than in controls both in particulate and in soluble fractions. The authors suggest that the altered subcellular distribution found in neurogenic atrophy might be due to the loss of nerve trophic control.

Topics: Cyclic AMP; Cyclic GMP; Cytosol; Humans; Kinetics; Mitochondria, Muscle; Muscles; Muscular Atrophy; Muscular Diseases; Muscular Dystrophies; Protein Kinases; Subcellular Fractions

The authors radioimmunoassayed cyclic nucleotide concentrations in plasma and biopsied muscles of muscular dystrophy and muscles of chicken embryo. c-AMP concentrations in plasma were significantly lowered in Duchenne-type muscular dystrophy and this lowered degree was correlated with the stage of progression. Plasma c-GMP levels were also depressed in Duchenne-type dystrophy. In biopsied muscles, c-AMP concentrations per milligram of non-collagen protein were within normal limits. Therefore, the decrease of plasma c-AMP concentrations might be an expression of total metabolic changes rather than a pathologic process of the muscle itself. As for the dystrophic chicken embryo, both c-AMP and GMP concentrations were decreasing in the pectoral muscles in parallel with the advancement of hatching stages.

Topics: Animals; Chick Embryo; Cyclic AMP; Cyclic GMP; Humans; Mice; Muscles; Muscular Dystrophies; Muscular Dystrophy, Animal; Radioimmunoassay

Guanylate cyclase activity has been studied in muscle of normal subjects and of patients suffering from muscular and neuromuscular diseases. In normal tissue a guanylate cyclase activity was found in both soluble and particulate fractions of homogenate. We found also that the kinetic analysis of the enzyme of soluble differed from that of particulate fraction. A decrease of guanylate cyclase activity in crude homogenate was observed in muscular dystrophies, in neuromuscular atrophies, and in inflammatory forms of muscle disease.

Topics: Cyclic GMP; Guanylate Cyclase; Humans; Mitochondria, Muscle; Muscles; Muscular Atrophy; Muscular Diseases; Muscular Dystrophies; Myasthenia Gravis; Myositis

Topics: Cyclic AMP; Cyclic GMP; Humans; Muscles; Muscular Diseases; Muscular Dystrophies; Phosphoric Diester Hydrolases

Topics: Adolescent; Adult; Age Factors; Aged; Amyotrophic Lateral Sclerosis; Bulbar Palsy, Progressive; Cyclic AMP; Cyclic GMP; Female; Glucagon; Humans; Male; Middle Aged; Muscular Atrophy; Muscular Dystrophies; Myositis; Neuromuscular Diseases; Nucleotides, Cyclic; Radioimmunoassay