title: Oxidative stress and ca(2+) release events in mouse cardiomyocytes.
abstract: Cellular oxidative stress, associated with a variety of common cardiac diseases, is well recognized to affect the function of several key proteins involved in Ca(2+) signaling and excitation-contraction coupling, which are known to be exquisitely sensitive to reactive oxygen species. These include the Ca(2+) release channels of the sarcoplasmic reticulum (ryanodine receptors or RyR2s) and the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Oxidation of RyR2s was found to increase the open probability of the channel, whereas CaMKII can be activated independent of Ca(2+) through oxidation. Here, we investigated how oxidative stress affects RyR2 function and SR Ca(2+) signaling in situ, by analyzing Ca(2+) sparks in permeabilized mouse cardiomyocytes under a broad range of oxidative conditions. The results show that with increasing oxidative stress Ca(2+) spark duration is prolonged. In addition, long and very long-lasting (up to hundreds of milliseconds) localized Ca(2+) release events started to appear, eventually leading to sarcoplasmic reticulum (SR) Ca(2+) depletion. These changes of release duration could be prevented by the CaMKII inhibitor KN93 and did not occur in mice lacking the CaMKII-specific S2814 phosphorylation site on RyR2. The appearance of long-lasting Ca(2+) release events was paralleled by an increase of RyR2 oxidation, but also by RyR-S2814 phosphorylation, and by CaMKII oxidation. Our results suggest that in a strongly oxidative environment oxidation-dependent activation of CaMKII leads to RyR2 phosphorylation and thereby contributes to the massive prolongation of SR Ca(2+) release events.
authors.affiliation: Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey. Electronic address: nshiroko@njms.rutgers.edu.
authors.forename: Natalia
authors.initials: N
authors.lastname: Shirokova
authors.affiliation: Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey.
authors.forename: Chifei
authors.initials: C
authors.lastname: Kang
authors.affiliation: Department of Physiology, University of Bern, Bern, Switzerland.
authors.forename: Miguel
authors.initials: M
authors.lastname: Fernandez-Tenorio
authors.affiliation: Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas.
authors.forename: Qiongling
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas.
authors.forename: Xander H T
authors.initials: XHT
authors.lastname: Wehrens
authors.affiliation: Department of Physiology, University of Bern, Bern, Switzerland. Electronic address: niggli@pyl.unibe.ch.
authors.forename: Ernst
authors.initials: E
authors.lastname: Niggli
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D002478:Cells, Cultured; D051379:Mice; D008810:Mice, Inbred C57BL; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018384:Oxidative Stress; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
chemical_list: D019837:Ryanodine Receptor Calcium Release Channel; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2