Orai1 and Stim1 regulate normal and hypertrophic growth in cardiomyocytes

Voelkers, Mirko; Salz, Mareen; Herzog, Nicole; Frank, Derk; Dolatabadi, Nima; Frey, Norbert; Gude, Natalie; Friedrich, Oliver; Koch, Walter J.; Katus, Hugo A.; Sussman, Mark A.; Most, Patrick

doi:10.1016/j.yjmcc.2010.01.020

« Previous Next »Journal of Molecular and Cellular Cardiology
Volume 48, Issue 6 , Pages 1329-1334, June 2010

Orai1 and Stim1 regulate normal and hypertrophic growth in cardiomyocytes

Mirko Voelkers
- Department of Internal Medicine III, Laboratory for Molecular and Translational Cardiology, Division of Cardiology, INF 350, University of Heidelberg, 69120 Heidelberg, Germany
- Corresponding authors. M. Voelkers is to be contacted at the Department of Internal Medicine III, University of Heidelberg, 69120 Heidelberg, Germany. P. Most, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Mareen Salz
- Department of Internal Medicine III, Laboratory for Molecular and Translational Cardiology, Division of Cardiology, INF 350, University of Heidelberg, 69120 Heidelberg, Germany
Nicole Herzog
- Department of Internal Medicine III, Laboratory for Molecular and Translational Cardiology, Division of Cardiology, INF 350, University of Heidelberg, 69120 Heidelberg, Germany
Derk Frank
- Department of Internal Medicine III, Laboratory for Molecular and Translational Cardiology, Division of Cardiology, INF 350, University of Heidelberg, 69120 Heidelberg, Germany
Nima Dolatabadi
- San Diego Heart Institute, San Diego State University, San Diego, CA 92182, USA
Norbert Frey
- Department of Cardiology and Angiology, University of Kiel, Schittenhelmstraβe 12, 24105 Kiel, Germany
Natalie Gude
- San Diego Heart Institute, San Diego State University, San Diego, CA 92182, USA
Oliver Friedrich
- Institute of Physiology and Pathophysiology, Medical Biophysics, INF 326, University of Heidelberg, 69120 Heidelberg, Germany
Walter J. Koch
- Center for Translational Medicine, Laboratory for Cardiac Stem Cell and Gene Therapy, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
Hugo A. Katus
- Department of Internal Medicine III, Laboratory for Molecular and Translational Cardiology, Division of Cardiology, INF 350, University of Heidelberg, 69120 Heidelberg, Germany
Mark A. Sussman
- San Diego Heart Institute, San Diego State University, San Diego, CA 92182, USA
Patrick Most
- Department of Internal Medicine III, Laboratory for Molecular and Translational Cardiology, Division of Cardiology, INF 350, University of Heidelberg, 69120 Heidelberg, Germany
- Center for Translational Medicine, Laboratory for Cardiac Stem Cell and Gene Therapy, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
- Corresponding authors. M. Voelkers is to be contacted at the Department of Internal Medicine III, University of Heidelberg, 69120 Heidelberg, Germany. P. Most, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.

Received 9 December 2009; received in revised form 23 January 2010; accepted 28 January 2010. published online 08 February 2010.

Abstract

Cardiac hypertrophy is an independent risk for heart failure (HF) and sudden death. Deciphering signalling pathways dependent on extracellular calcium (Ca²⁺) influx that control normal and pathological cardiac growth may enable identification of novel therapeutic targets. The objective of the present study is to determine the role of the Ca²⁺ release-activated Ca²⁺ (CRAC) channel Orai1 and stromal interaction molecule 1 (Stim1) in postnatal cardiomyocyte store operated Ca²⁺ entry (SOCE) and impact on normal and hypertrophic postnatal cardiomyocyte growth. Employing a combination of siRNA-mediated gene silencing, cultured neonatal rat ventricular cardiomyocytes together with indirect immunofluorescence, epifluorescent Ca²⁺ imaging and site-specific protein phosphorylation and real-time mRNA expression analysis, we show for the first time that both Orai1 and Stim1 are present in cardiomyocytes and required for SOCE due to intracellular Ca²⁺ store depletion by thapsigargin. Stim1-KD but not Orai1-KD significantly decreased diastolic Ca²⁺ levels and caffeine-releasable Ca²⁺ from the sarcoplasmic reticulum (SR). Conversely, Orai1-KD but not Stim1-KD significantly diminished basal NRCM cell size, anp and bnp mRNA levels and activity of the calcineurin (CnA) signalling pathway although diminishing both Orai1 and Stim1 proteins similarly attenuated calmodulin kinase II (CamKII) and ERK1/2 activity under basal conditions. Both Orai1- and Stim1-KD completely abrogated phenylephrine (PE) mediated hypertrophic NRCM growth and enhanced natriuretic factor expression by inhibiting G_q-protein conveyed activation of the CamKII and ERK1/2 signalling pathway. Interestingly, only Orai1-KD but not Stim1-KD prevented Gq-mediated CaN-dependent prohypertrophic signalling. This study shows for the first time that both Orai1 and Stim1 have a key role in cardiomyocyte SOCE regulating both normal and hypertrophic postnatal cardiac growth in vitro.