title: Nuclear Ca2+ sparks and waves mediated by inositol 1,4,5-trisphosphate receptors in neonatal rat cardiomyocytes.
abstract: Dynamic nuclear Ca(2+) signals play pivotal roles in diverse cellular functions including gene transcription, cell growth, differentiation, and apoptosis. Here we report a novel nuclear Ca(2+) regulatory mechanism mediated by inositol 1,4,5-trisphosphate receptors (IP(3)Rs) around the nucleus in developing cardiac myocytes. Activation of IP(3)Rs by alpha(1)-adrenergic receptor (alpha(1)AR) stimulation or by IP(3) application (in saponin-permeabilized cells) increases Ca(2+) spark frequency preferentially in the region around the nucleus in neonatal rat ventricular myocytes. A nuclear enrichment of IP(3)R distribution supports the higher responsiveness of Ca(2+) release in this particular region. Strikingly, we observed "nuclear Ca(2+)waves" that engulf the entire nucleus without spreading into the bulk cytosol. alpha(1)AR stimulation enhances the occurrence of nuclear Ca(2+) waves and confers them the ability to trigger cytosolic Ca(2+) waves via IP(3)R-dependent pathways. This finding accounts, at least partly, for a profound frequency-dependent modulation of global Ca(2+) oscillations during alpha(1)AR stimulation. Thus, IP(3)R-mediated Ca(2+) waves traveling in the nuclear region provide active, autonomous regulation of nuclear Ca(2+) signaling, which provides for not only the local signal transduction, but also a pacemaker to drive global Ca(2+) transient in the context of alpha(1)AR stimulation in developing cardiac myocytes.
authors.affiliation: Department of Pharmacology, School of Chemical Biology & Pharmaceutical Sciences, Capital Medical University, Beijing 100069, China. luodl@bjmu.edu.cn
authors.forename: Dali
authors.initials: D
authors.lastname: Luo
authors.forename: Dongmei
authors.initials: D
authors.lastname: Yang
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Lan
authors.forename: Kaitao
authors.initials: K
authors.lastname: Li
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.forename: Ju
authors.initials: J
authors.lastname: Chen
authors.forename: Youyi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Rui-Ping
authors.initials: RP
authors.lastname: Xiao
authors.forename: Qide
authors.initials: Q
authors.lastname: Han
authors.forename: Heping
authors.initials: H
authors.lastname: Cheng
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D020013:Calcium Signaling / Q000502:physiology*; D002463:Cell Membrane Permeability; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000187:drug effects / Q000502:physiology*; D018613:Microscopy, Confocal; D032383:Myocytes, Cardiac / Q000502:physiology*; D009685:Nuclear Envelope / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology
chemical_list: D000316:Adrenergic alpha-Agonists; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine