title: Reversible oxidation of vicinal-thiols motif in sarcoplasmic reticulum calcium regulatory proteins is involved in muscle fatigue mechanism.
abstract: The mechanism underlying fatigue in skeletal muscle (SM) related to the redox-potential hypothesis, ranges from a direct effect of oxygen reactive species, to a number of other free radical intermediates targeting specific amino acids in the Ca(2+)-regulatory proteins of the sarcoplasmic reticulum (SR). In the present study, we investigate the selective oxidation/reduction of the protein motif Cys-(Xn=2-6)-Cys, known as a vicinal thiol group (VTG), present in the SR Ca(2+)-ATPase (SERCA) and in the Ca(2+)-channel ryanodine receptor (RyR) which are modified during muscle fatigue in SM. Selective oxidation of VTG with phenyl arsine oxide (PAO) increases fatigue in rat isolated SM and fatigue is prevented when muscle is previously incubated with a VTG selective reducing agent, 2,3-dimercaptopropanol (British anti-Lewisite (BAL)). In isolated SR membranes, PAO [<0.1mM] modifies SERCA conformation and inhibits ATPase activity but does not affect Ca(2+)-release. However, PAO at [>0.1mM] inhibits SERCA and RyR activities in a reversible manner by selectively reducing them. Interestingly, as observed by differential scanning calorimetry, the conformation of SERCA from fatigued muscle changed in a similar manner as when SERCA VTG where oxidized. The addition of BAL to fatigued muscle restored the structural conformation and activity of SERCA with full recovery of muscle force production after fatigue. We conclude that VTG reversible oxidation of SR Ca(2+) regulatory proteins are involved in muscle contraction/relaxation and are a molecular mechanism to be considered for muscle fatigue.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico; Department of Toxicology and Pharmacology, Faculty of Chemistry, Universidad Autónoma del Estado de México, Mexico; Grenoble Institut des Neurosciences, Université Joseph Fourier, LabEx Ion Channel Science and Therapeutics, France.
authors.forename: Pável
authors.initials: P
authors.lastname: Vázquez
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico.
authors.forename: Aldo
authors.initials: A
authors.lastname: Tirado-Cortés
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico.
authors.forename: Rocío
authors.initials: R
authors.lastname: Álvarez
authors.affiliation: Grenoble Institut des Neurosciences, Université Joseph Fourier, LabEx Ion Channel Science and Therapeutics, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Ronjat
authors.affiliation: Department of Toxicology and Pharmacology, Faculty of Chemistry, Universidad Autónoma del Estado de México, Mexico.
authors.forename: Araceli
authors.initials: A
authors.lastname: Amaya
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico; Department of Biochemistry, National Institute of Perinatology, Mexico. Electronic address: aortega@unam.mx.
authors.forename: Alicia
authors.initials: A
authors.lastname: Ortega
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D013438:Sulfhydryl Compounds; D003545:Cysteine; D002118:Calcium
keywords: Fatigue; Redox; Ryanodine receptor; SERCA; Skeletal muscle; Vicinal thiols