Journal
HYPERTENSION
Volume 64, Issue 6, Pages 1368-U438Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1161/HYPERTENSIONAHA.114.03743
Keywords
autonomic nervous system; hypertension; proteasome endopeptidase complex; renin-angiotensin system
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Funding
- National Institutes of Health [P20-GM103514, R01-HL093178]
- American Heart Association
- LSU Research Enhancement Fund
- Howard University
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Angiotensin-converting enzyme type 2 (ACE2) is a pivotal component of the renin-angiotensin system, promoting the conversion of angiotensin II (Ang-II) to Ang-(1-7). We previously reported that decreased ACE2 expression and activity contributes to the development of Ang-II-mediated hypertension in mice. The present study aimed to investigate the mechanisms involved in ACE2 downregulation during neurogenic hypertension. In ACE2-transfected Neuro-2A cells, Ang-II treatment resulted in a significant attenuation of ACE2 enzymatic activity. Examination of the subcellular localization of ACE2 revealed that Ang-II treatment leads to ACE2 internalization and degradation into lysosomes. These effects were prevented by both the Ang-II type 1 receptor (AT(1)R) blocker losartan and the lysosomal inhibitor leupeptin. In contrast, in HEK293T cells, which lack endogenous AT(1)R, Ang-II failed to promote ACE2 internalization. Moreover, this effect could be induced after AT(1)R transfection. Furthermore, coimmunoprecipitation experiments demonstrated that AT(1)R and ACE2 form complexes, and these interactions were decreased by Ang-II treatment, which also enhanced ACE2 ubiquitination. In contrast, ACE2 activity was not changed by transfection of AT(2) or Mas receptors. In vivo, Ang-II-mediated hypertension was blunted by chronic infusion of leupeptin in wildtype C57Bl/6, but not in ACE2 knockout mice. Overall, this is the first demonstration that elevated Ang-II levels reduce ACE2 expression and activity by stimulation of lysosomal degradation through an AT(1)R-dependent mechanism.
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