title: Cardiomyocyte Circadian Oscillations Are Cell-Autonomous, Amplified by β-Adrenergic Signaling, and Synchronized in Cardiac Ventricle Tissue.
abstract: Circadian clocks impact vital cardiac parameters such as blood pressure and heart rate, and adverse cardiac events such as myocardial infarction and sudden cardiac death. In mammals, the central circadian pacemaker, located in the suprachiasmatic nucleus of the hypothalamus, synchronizes cellular circadian clocks in the heart and many other tissues throughout the body. Cardiac ventricle explants maintain autonomous contractions and robust circadian oscillations of clock gene expression in culture. In the present study, we examined the relationship between intrinsic myocardial function and circadian rhythms in cultures from mouse heart. We cultured ventricular explants or dispersed cardiomyocytes from neonatal mice expressing a PER2::LUC bioluminescent reporter of circadian clock gene expression. We found that isoproterenol, a β-adrenoceptor agonist known to increase heart rate and contractility, also amplifies PER2 circadian rhythms in ventricular explants. We found robust, cell-autonomous PER2 circadian rhythms in dispersed cardiomyocytes. Single-cell rhythms were initially synchronized in ventricular explants but desynchronized in dispersed cells. In addition, we developed a method for long-term, simultaneous monitoring of clock gene expression, contraction rate, and basal intracellular Ca2+ level in cardiomyocytes using PER2::LUC in combination with GCaMP3, a genetically encoded fluorescent Ca2+ reporter. In contrast to robust PER2 circadian rhythms in cardiomyocytes, we detected no rhythms in contraction rate and only weak rhythms in basal Ca2+ level. In summary, we found that PER2 circadian rhythms of cardiomyocytes are cell-autonomous, amplified by adrenergic signaling, and synchronized by intercellular communication in ventricle explants, but we detected no robust circadian rhythms in contraction rate or basal Ca2+.
authors.affiliation: Center for Circadian Biology, University of California San Diego, La Jolla, California, United States of America.|Department of Psychiatry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Stephen
authors.initials: S
authors.lastname: Beesley
authors.affiliation: Center for Circadian Biology, University of California San Diego, La Jolla, California, United States of America.|Department of Psychiatry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Takako
authors.identifier: http://orcid.org/0000-0002-0222-7693
authors.initials: T
authors.lastname: Noguchi
authors.affiliation: Center for Circadian Biology, University of California San Diego, La Jolla, California, United States of America.|Department of Psychiatry, University of California San Diego, La Jolla, California, United States of America.|Veterans Affairs San Diego Healthcare System, San Diego, California, United States of America.
authors.forename: David K
authors.initials: DK
authors.lastname: Welsh
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002450:Cell Communication; D002478:Cells, Cultured; D057906:Circadian Clocks / Q000502:physiology*; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism*; D008163:Luminescent Measurements; D051379:Mice; D008822:Mice, Transgenic; D009200:Myocardial Contraction / Q000235:genetics; D032383:Myocytes, Cardiac / Q000378:metabolism*; D056950:Period Circadian Proteins / Q000235:genetics; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015398:Signal Transduction; D016276:Ventricular Function / Q000187:drug effects / Q000235:genetics
chemical_list: D056925:Circadian Rhythm Signaling Peptides and Proteins; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D011943:Receptors, Adrenergic, beta; D002118:Calcium