Stimulus-dependent regulation of nuclear Ca2+ signaling in cardiomyocytes: a role of neuronal calcium sensor-1

PLoS One. 2015 Apr 21;10(4):e0125050. doi: 10.1371/journal.pone.0125050. eCollection 2015.

Abstract

In cardiomyocytes, intracellular calcium (Ca2+) transients are elicited by electrical and receptor stimulations, leading to muscle contraction and gene expression, respectively. Although such elevations of Ca2+levels ([Ca2+]) also occur in the nucleus, the precise mechanism of nuclear [Ca2+] regulation during different kinds of stimuli, and its relationship with cytoplasmic [Ca2+] regulation are not fully understood. To address these issues, we used a new region-specific fluorescent protein-based Ca2+ indicator, GECO, together with the conventional probe Fluo-4 AM. We confirmed that nuclear Ca2+ transients were elicited by both electrical and receptor stimulations in neonatal mouse ventricular myocytes. Kinetic analysis revealed that electrical stimulation-elicited nuclear Ca2+ transients are slower than cytoplasmic Ca2+ transients, and chelating cytoplasmic Ca2+ abolished nuclear Ca2+ transients, suggesting that nuclear Ca2+ are mainly derived from the cytoplasm during electrical stimulation. On the other hand, receptor stimulation such as with insulin-like growth factor-1 (IGF-1) preferentially increased nuclear [Ca2+] compared to cytoplasmic [Ca2+]. Experiments using inhibitors revealed that electrical and receptor stimulation-elicited Ca2+ transients were mainly mediated by ryanodine receptors and inositol 1,4,5-trisphosphate receptors (IP3Rs), respectively, suggesting different mechanisms for the two signals. Furthermore, IGF-1-elicited nuclear Ca2+ transient amplitude was significantly lower in myocytes lacking neuronal Ca2+ sensor-1 (NCS-1), a Ca2+ binding protein implicated in IP3R-mediated pathway in the heart. Moreover, IGF-1 strengthened the interaction between NCS-1 and IP3R. These results suggest a novel mechanism for receptor stimulation-induced nuclear [Ca2+] regulation mediated by IP3R and NCS-1 that may further fine-tune cardiac Ca2+ signal regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aniline Compounds
  • Animals
  • Animals, Newborn
  • Calcium / metabolism*
  • Calcium Signaling
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • Cytoplasm / drug effects
  • Cytoplasm / metabolism
  • Electric Stimulation
  • Fluorescent Dyes
  • Gene Expression Regulation
  • Heart Ventricles / cytology
  • Heart Ventricles / drug effects
  • Heart Ventricles / metabolism
  • Inositol 1,4,5-Trisphosphate Receptors / genetics*
  • Inositol 1,4,5-Trisphosphate Receptors / metabolism
  • Insulin-Like Growth Factor I / pharmacology*
  • Ion Transport
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism*
  • Neuronal Calcium-Sensor Proteins / deficiency
  • Neuronal Calcium-Sensor Proteins / genetics*
  • Neuropeptides / deficiency
  • Neuropeptides / genetics*
  • Primary Cell Culture
  • Ryanodine Receptor Calcium Release Channel / genetics
  • Ryanodine Receptor Calcium Release Channel / metabolism
  • Xanthenes

Substances

  • Aniline Compounds
  • Fluo 4
  • Fluorescent Dyes
  • Inositol 1,4,5-Trisphosphate Receptors
  • Neuronal Calcium-Sensor Proteins
  • Neuropeptides
  • Ryanodine Receptor Calcium Release Channel
  • Xanthenes
  • frequenin calcium sensor proteins
  • insulin-like growth factor-1, mouse
  • Insulin-Like Growth Factor I
  • Calcium

Grants and funding

This work was supported by JSPS KAKENHI, Grant-in-Aid for Young Scientists (B) #25860174 (http://www.jsps.go.jp/j-grantsinaid/03_keikaku/download.html) that SN received, Grant-in-Aid for Scientific Research (C) #24590293 (http://www.jsps.go.jp/j-grantsinaid/03_keikaku/download.html) that TYN received, The Naito Science & Engineering Foundation #J004 (https://www.naito-f.or.jp/jp/joseikn/jo_index.php?data=detail&grant_id=KEN) that TYN received, and by Intramural Research Fund for Cardiovascular Disease of the National Cerebral and Cardiovascular Center #22-2-3 that SW received. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.