Angiotensin II up-regulates Angiotensin I-Converting Enzyme (ACE), but down-regulates ACE2 via the AT1-ERK/p38 MAP kinase pathway

Vijay Koka, Ru Huang Xiao, Arthur C.K. Chung, Wansheng Wang, Luan Truong, Hui Yao Lan

Research output: Contribution to journalArticle

177 Scopus citations

Abstract

The recent discovery of the angiotensin II (Ang II)-breakdown enzyme, angiotensin I converting enzyme (ACE) 2, suggests the importance of Ang II degradation in hypertension. The present study explored the signaling mechanism by which ACE2 is regulated under hypertensive conditions. Real-time PCR and immunohistochemistry showed that ACE2 mRNA and protein expression levels were high, whereas ACE expression levels were moderate in both normal kidney and heart. In contrast, patients with hypertension showed marked ACE up-regulation and ACE2 down-regulation in both hypertensive cardiopathy and, particularly, hypertensive nephropathy. The inhibition of ACE2 expression was shown to be associated with ACE up-regulation and activation of extracellular regulated (ERK)1/2 and p38 mitogen-activated protein (MAP) kinases. In vitro, Ang II was able to upregulate ACE and down-regulate ACE2 in human kidney tubular cells, which were blocked by an angiotensin II (AT)1 receptor antagonist (losartan), but not by an AT2 receptor blocker (PD123319). Furthermore, blockade of ERK1/2 or p38 MAP kinases by either specific inhibitors or a dominant-negative adenovirus was able to abolish Ang II-induced ACE2 down-regulation in human kidney tubular cells. In conclusion, Ang II is able to up-regulate ACE and down-regulate ACE2 expression levels under hypertensive conditions both in vivo and in vitro. The AT1 receptor-mediated ERK/p38 MAP kinase signaling pathway may be a key mechanism by which Ang II down-regulates ACE2 expression, implicating an ACE/ACE2 imbalance in hypertensive cardiovascular and renal damage.

Original languageEnglish (US)
Pages (from-to)1174-1183
Number of pages10
JournalAmerican Journal of Pathology
Volume172
Issue number5
DOIs
StatePublished - May 2008

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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