title: Cardiac endothelial cells regulate reactive oxygen species-induced cardiomyocyte apoptosis through neuregulin-1beta/erbB4 signaling.
abstract: Neuregulin (NRG)-1beta has a prosurvival effect on cardiac myocytes via the phosphatidylinositol-3-kinase/Akt pathway, but the physiological regulators of this system in the intact heart are unknown. In this study, we tested the hypothesis that reactive oxygen species regulate NRG/erbB signaling. We used isolated adult rat ventricular myocytes (ARVMs) or cardiac microvascular endothelial cells (CMECs) in monoculture, or together in coculture. H2O2 induced NRG-1beta release from CMECs in a concentration-dependent manner, and conditioned medium from H2O2-treated CMEC activated ARVM erbB4. NRG-1beta release occurred via proteolytic cleavage of 115-kDa transmembrane NRG-1beta and was inhibited by the metalloproteinase inhibitor 1,10-phenanthroline. In myocyte monoculture, H2O2 induced erbB4-dependent, but NRG-independent, activation of Akt. To elucidate the bioactivity of CMEC-derived NRG-1beta on ARVMs, we examined H2O2-induced myocyte apoptosis in co-culture using an antibody to NRG-1beta. The percentages of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells were significantly higher in the anti-NRG-1beta group than in the control group. The change in apoptosis induced by anti-NRG-1beta in co-culture was similar in magnitude to the protection of myocytes by addition of recombinant NRG-1beta to ARVM monocultures. Activation of NRG/erbB paracrine signaling was also seen in the intact heart subjected to oxidative stress by ischemia-reperfusion injury. Isolated perfused mouse hearts subjected to 15 min of ischemia, followed by 30 min of reperfusion, showed complete proteolytic cleavage of 115-kDa NRG-1beta, with concomitant erbB4 phosphorylation. These results demonstrate that reactive oxygen species activate NRG-1beta/erbB4 paracrine signaling in the heart and suggest that this system is involved in cardiac adaptation to oxidative stress.
authors.affiliation: Center of Molecular Stress Response, Whitaker Cardiovascular Institute, Department of Medicine, Boston University Medical Center, Boston, Massachusetts 02118, USA.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kuramochi
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Cote
authors.forename: Xinxin
authors.initials: X
authors.lastname: Guo
authors.forename: Nathan K
authors.initials: NK
authors.lastname: Lebrasseur
authors.forename: Lei
authors.initials: L
authors.lastname: Cui
authors.forename: Ronglih
authors.initials: R
authors.lastname: Liao
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Sawyer
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D018920:Coculture Techniques; D003432:Cross-Linking Reagents / Q000494:pharmacology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D047468:Immunoprecipitation; D020287:In Situ Nick-End Labeling; D051379:Mice; D008833:Microcirculation; D009206:Myocardium / Q000378:metabolism*; D020890:Neuregulin-1 / Q000378:metabolism*; D010477:Perfusion; D010618:Phenanthrolines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins / Q000737:chemistry; D015427:Reperfusion Injury; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D003432:Cross-Linking Reagents; D017077:Culture Media, Conditioned; D006861:Hydrogen Peroxide; D020890:Neuregulin-1; D010618:Phenanthrolines; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; C494918:AKT1 protein, human; C494920:Akt1 protein, rat; C025205:1,10-phenanthroline