Neuregulin-1beta1 rapidly modulates nitric oxide synthesis and calcium handling in rat cardiomyocytes.
OBJECTIVE
The ErbB-neuregulin-1β1 (Nrg1β1) pathway is required for cardiac development and exerts chronic effects on the postnatal adult heart. Long-term application of Nrg1β1 results in hypertrophy and protection against oxidative stress and cytotoxic agents. We performed experiments with acute Nrg1β1 treatment to find evidence for a further protective role due to rapid modulation of adult cardiomyocyte function.


RESULTS
In confocal fluorimetric measurements, Nrg1β1 induced a calcium-independent increase in nitric oxide (NO) production in isolated adult rat ventricular myocytes (ARVCMs) that was blocked by the phosphoinositide-3-kinase (PI3K) inhibitor Wortmannin. Western blot analysis showed enhancement of endothelial nitric oxide synthase phosphorylation in Nrg1β1-treated ARVCMs, which was attenuated by Wortmannin. Nrg1β1 induced a significant increase in calcium transient amplitude (indo-1 ratiometric measurement) and accelerated the recovery of cytosolic calcium in the sarcoplasmic reticulum without affecting whole-cell L-type calcium current. Wortmannin or the protein kinase G inhibiting peptide (DT-2) abolished the increase in calcium transient amplitude and the acceleration of calcium recovery induced by Nrg1β1 treatment. Immunofluorescence analysis revealed that Nrg1β1 treatment increased phospholamban phosphorylation, and the effect was blocked by PI3K and protein kinase G inhibition. Caffeine-releasable sarcoplasmic reticulum calcium content was also higher during Nrg1β1 administration.


CONCLUSIONS
Rapid activation of PI3K, endothelial nitric oxide synthase and protein kinase G and a consequent improvement in diastolic calcium can be added to established Nrg1 protective roles.
Brero
Alessia
A
Department of Animal and Human Biology, University of Turin, Via Accademia Albertina 13, 10123, Turin, Italy.
Ramella
Roberta
R
Fitou
Amandine
A
Dati
Claudio
C
Alloatti
Giuseppe
G
Gallo
Maria Pia
MP
Levi
Renzo
R
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005260:Female; D005452:Fluoresceins / Q000494:pharmacology; D023421:Models, Animal; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D020890:Neuregulin-1 / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D000077191:Wortmannin; D000099211:Phospholamban
D000730:Androstadienes; D002118:Calcium; D002135:Calcium-Binding Proteins; D017869:Cyclic GMP-Dependent Protein Kinases; D005452:Fluoresceins; D020890:Neuregulin-1; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D010446:Peptide Fragments; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D000077191:Wortmannin; D000099211:Phospholamban; C513505:DT-2 compound; C117467:neuregulin beta