Abstract
Circulating levels of arginine vasopressin (AVP) are elevated during hypovolemia and during cardiac stress. AVP activates arginine vasopressin type 1A (V1A)/Gαq–coupled receptors in the heart and vasculature and V2/Gαs–coupled receptors in the kidney. However, little is known regarding the signaling pathways that influence the effects of V1A receptor (V1AR) activation during cellular injury. Using hypoxia-reoxygenation (H/R) as a cell injury model, we evaluated cell survival and caspase 3/7 activity in H9c2 myoblasts after treatment with AVP. Pretreatment of H9c2 cells with AVP significantly reduced H/R-induced cell death and caspase 3/7 activity, effects that were blocked via both selective V1AR inhibition and mitogen-activated protein kinase (MEK1/2) inhibition. AVP increased extracellular-regulated kinase 1/2 (ERK1/2) phosphorylation in a concentration-dependent manner that was sensitive to MEK1/2 inhibition and V1AR inhibition, but not V1BR or V2R inhibition. Discrete elements of the V1A/Gαq-protein kinase C (PKC) and V1A/G protein–coupled receptor kinase (GRK)/β-arrestin signaling cascades were inhibited to dissect the pathways responsible for the protective effects of V1AR signaling: Gαq (overexpression of Gq-I-ires-green fluorescent protein), PKC (administration of Ro 31-82425; 2-[8-(aminomethyl)-6,7,8,9-tetrahydropyrido[1,2-a]indol-3-yl]-3-(1-methyl-1H-indol-3-yl)maleimide, HCl, bisindolylmaleimide X, HCl), GRK2 [C-terminal GRK2 peptide overexpression and small interfering RNA (siRNA) knockdown], GRK5 (siRNA knockdown), and β-arrestin1 (siRNA knockdown). These studies demonstrated that both Gαq/PKC- and GRK2/β-arrestin1–dependent V1AR signaling were capable of inducing ERK1/2 phosphorylation in response to AVP stimulation. However, AVP-mediated protection against H/R was elicited only via GRK2- and β-arrestin1–dependent signaling. These results suggest that activation of the V1AR in H9c2 cells mediates protective signaling via a GRK2/β−arrestin1/ERK1/2–dependent mechanism that leads to decreased caspase 3/7 activity and enhanced survival under conditions of ischemic stress.
Footnotes
- Received March 15, 2013.
- Accepted May 20, 2013.
This work was supported by the National Institutes of Health National Heart, Lung, and Blood Institute [Grants HL105414 and HL091799].
↵
This article has supplemental material available at molpharm.aspetjournals.org.
- Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|
