title: Oxidative stress decreases microtubule growth and stability in ventricular myocytes.
abstract: Microtubules (MTs) have many roles in ventricular myocytes, including structural stability, morphological integrity, and protein trafficking. However, despite their functional importance, dynamic MTs had never been visualized in living adult myocytes. Using adeno-associated viral vectors expressing the MT-associated protein plus end binding protein 3 (EB3) tagged with EGFP, we were able to perform live imaging and thus capture and quantify MT dynamics in ventricular myocytes in real time under physiological conditions. Super-resolution nanoscopy revealed that EB1 associated in puncta along the length of MTs in ventricular myocytes. The vast (~80%) majority of MTs grew perpendicular to T-tubules at a rate of 0.06μm∗s(-1) and growth was preferentially (82%) confined to a single sarcomere. Microtubule catastrophe rate was lower near the Z-line than M-line. Hydrogen peroxide increased the rate of catastrophe of MTs ~7-fold, suggesting that oxidative stress destabilizes these structures in ventricular myocytes. We also quantified MT dynamics after myocardial infarction (MI), a pathological condition associated with increased production of reactive oxygen species (ROS). Our data indicate that the catastrophe rate of MTs increases following MI. This contributed to decreased transient outward K(+) currents by decreasing the surface expression of Kv4.2 and Kv4.3 channels after MI. On the basis of these data, we conclude that, under physiological conditions, MT growth is directionally biased and that increased ROS production during MI disrupts MT dynamics, decreasing K(+) channel trafficking.
authors.affiliation: Department of Physiology & Biophysics, University of Washington School of Medicine, Seattle, WA 98195, United States.
authors.forename: Benjamin M L
authors.initials: BM
authors.lastname: Drum
authors.affiliation: Department of Physiology & Biophysics, University of Washington School of Medicine, Seattle, WA 98195, United States.
authors.forename: Can
authors.initials: C
authors.lastname: Yuan
authors.affiliation: Department of Physiology & Biophysics, University of Washington School of Medicine, Seattle, WA 98195, United States.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Physiology & Biophysics, University of Washington School of Medicine, Seattle, WA 98195, United States.
authors.forename: Qinghang
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Physiology & Biophysics, University of Washington School of Medicine, Seattle, WA 98195, United States.
authors.forename: Linda
authors.initials: L
authors.lastname: Wordeman
authors.affiliation: Deparment of Physiology & Membrane Biology, University of California School of Medicine, Davis, CA 95616, United States. Electronic address: lfsantana@ucdavis.edu.
authors.forename: L Fernando
authors.initials: LF
authors.lastname: Santana
mesh_terms: D000818:Animals; D006352:Heart Ventricles / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D009203:Myocardial Infarction / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018384:Oxidative Stress; D011485:Protein Binding; D021381:Protein Transport; D014404:Tubulin / Q000378:metabolism
chemical_list: C584107:EB1 protein, mouse; D008869:Microtubule-Associated Proteins; D014404:Tubulin
keywords: Cardiomyocytes; Live imaging; Microtubule dynamics; Myocardial infarction; Oxidative stress; Transient outward current