Ang(1-7) influences ET-1 signaling through Mas: ETBR interactions: implications in pulmonary hypertension

Hood, K. Y., Yusuf, H., Findlay, J. E., Santos, R. A., Castro, C. H., Baillie, G. S. , MacLean, M. R., Montezano, A. and Touyz, R. M. (2016) Ang(1-7) influences ET-1 signaling through Mas: ETBR interactions: implications in pulmonary hypertension. Journal of Hypertension, 34(Supl 1), e216. (doi: 10.1097/01.hjh.0000500475.07008.db) (PMID:27754060)

Abstract

Objective: Ang(1-7) has been shown to protect against pulmonary hypertension (PH). Mechanisms remain unclear. Considering the importance of ET-1 in PH pathophysiology and endothelial dysfunction, we questioned whether Ang(1-7) influences ET-1 signaling in endothelial cells and whether Ang(1-7) treatment influences the ET-1 system in PH. Design and Method: Human endothelial cells (hEC) were stimulated with ET-1 in absence/presence of Ang(1-7). Mas and ETBR interaction was observed by immunoprecipitation. To characterize physical interactions, we utilized novel technology, employing a library of peptides spanning the MasR sequence, to define sites of ETBR binding. To investigate pathophysiological significance of our findings, we investigated whether Ang(1-7) treatment ameliorates PH. Hypoxia was used to induce PH in mice: normoxic (NV) and hypoxic vehicle (HV), normoxic (NA) and hypoxic PH (HA) treated with Ang(1-7) 30 [mu]g/kg/day. Results: Ang(1-7) increases ET-1 release (125%) and ETBR protein (50%). ET-1-induced increases in VCAM-1 protein (38%) and TNF[alpha] production (30%) were blocked by Ang(1-7). Pro-inflammatory effects were dependent on NO. Ang(1-7) increased NO production (257%) in a Mas and ETBR-dependent manner. Mutagenesis studies identified regions conferring specificity for ETBR binding. Peptide disruptors to prevent Mas/ETBR interaction were used for in vitro validation. We previously demonstrated in hEC that Ang(1-7) stimulates eNOS phosphorylation (180%), an effect inhibited by pre-incubation with peptide disruptors. In HP mice, RVSP (18.7 NV vs. 47.6mmHg HV, p < 0.05) RVH (0.19 NV vs. 0.28 HV, p < 0.01) and ET-1 levels (0.8 NV vs 2.4pg/ml HV, p < 0.05) were increased and blocked by Ang(1-7). Hypercontractility in pulmonary arteries of HV mice was attenuated by Ang(1-7). Conclusions: These findings indicate that vasoprotective effects of Ang(1-7) may be mediated through Mas:ETBR dimerization. In vivo studies support a relationship between Ang(1-7)/Mas and ET-1 systems. In conclusion we have identified a novel link between Ang(1-7) and ET-1 through physical interactions between Mas and ETBR.

• Item Type: Articles
• Additional Information: Conference information: The 26th Scientific Meeting of the International Society of Hypertension (ISH 2016), Seoul, Korea, 24-29 Sept 2016
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacLean, Professor Margaret and Harvey, Dr Katie and Baillie, Professor George and Montezano, Dr Augusto and Findlay, Mrs Jane and Touyz, Professor Rhian
• Authors: Hood, K. Y., Yusuf, H., Findlay, J. E., Santos, R. A., Castro, C. H., Baillie, G. S., MacLean, M. R., Montezano, A., and Touyz, R. M.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Journal of Hypertension
• Publisher: Lippincott Williams & Wilkins
• ISSN: 0263-6352
• ISSN (Online): 1473-5598