Angiotensin II regulates brain (pro)renin receptor expression through activation of cAMP response element-binding protein

Abstract

We reported that brain (pro)renin receptor (PRR) expression levels are elevated in DOCA-salt-induced hypertension; however, the underlying mechanism remained unknown. To address whether ANG II type 1 receptor (AT 1R) signaling is involved in this regulation, we implanted a DOCA pellet and supplied 0.9% saline as the drinking solution to C57BL/6J mice. Sham pellet-implanted mice that were provided regular drinking water served as controls. Concurrently, mice were intracerebroventricularly infused with the AT 1R blocker losartan, angiotensin-converting-enzyme inhibitor captopril, or artificial cerebrospinal fluid for 3 wk. Intracerebroventricular infusion of losartan or captopril attenuated DOCA-salt-induced PRR mRNA elevation in the paraventricular nucleus of the hypothalamus, suggesting a role for ANG II/AT 1R signaling in regulating PRR expression during DOCAsalt hypertension. To test which ANG II/AT 1R downstream transcription factors were involved in PRR regulation, we treated Neuro-2A cells with ANG II with or without CREB (cAMP response elementbinding protein) or AP-1 (activator protein-1) inhibitors, or CREB siRNA. CREB and AP-1 inhibitors, as well as CREB knockdown abolished ANG II-induced increases in PRR levels. ANG II also induced PRR upregulation in primary cultured neurons. Chromatin immunoprecipitation assays revealed that ANG II treatment increased CREB binding to the endogenous PRR promoter in both cultured neurons and hypothalamic tissues of DOCA-salt hypertensive mice. This increase in CREB activity was reversed by AT 1R blockade. Collectively, these findings indicate that ANG II acts via AT 1R to upregulate PRR expression both in cultured cells and in DOCA-salt hypertensive mice by increasing CREB binding to the PRR promoter.(pro)renin receptor; CAMP response element-binding protein; central nervous system; renin-angiotensin system; salt-sensitive hypertension THE BRAIN RENIN-ANGIOTENSIN system (RAS) plays an essential role in neurogenic hypertension (4, 21). The (pro)renin receptor (PRR) is a newly discovered component of the RAS that is highly expressed in the brain (16,26). Binding of renin to the PRR increases the catalytic activity of renin by approximately fourfold to fivefold. Prorenin also gains enzymatic activity by binding to the PRR (24). Binding of renin or prorenin to the PRR also directly initiates an intracellular signaling pathway independent of ANG II that increases the synthesis of profibrotic molecules, including plasminogen activator inhibitor-1, fibronectin, collagen, and transforming growth factor-␤ (10, 25, 26).We and others have reported that the PRR is upregulated in the central nervous system (CNS) in different hypertensive models, including spontaneously hypertensive rats (SHR) (27) and human renin-angiotensinogen (RA) double-transgenic hypertensive mice (16). Knocking down PRR in the brain through virus-mediated introduction of small hairpin (inhibitory) RNA against the PRR (PRR-shRNA) attenuates hypertension in both SHR and RA mice. We also recently reported that PR...

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

“…Transgenic rats overexpressing human PRR ubiquitously are normotensive, but show progressive development of nephropathy (454), whereas transgenic rats with smooth muscle specific PRR overexpression are hypertensive at 6 mo of age, which could be due to intra-adrenal ANG II-induced aldosterone generation (103). Likewise, brain PRR is hypothesized to regulate ANG II-dependent hypertensive responses (576,1179). In addition, PRR-dependent, but AT 1 R-indepednent effects have been reported in neuronal cells, including ROS production (814) and iNOS mRNA induction (406).…”

A novel synthetic activator of Nurr1 induces dopaminergic gene expression and protects against 6-hydroxydopamine neurotoxicity in vitro

“…Neuro-2a cells (N2A) and MN9D cells were cultured as previously described [12,4]. N27 cells were cultured in RPMI1640 medium (Life Technologies, Carlsbad, CA) supplemented with 10% FBS and 1X-PSN.…”

“…All cell-lines were undifferentiated with the exception of MN9D cells, which were differentiated by the addition of 1mM sodium butyrate in media (Sigma) for 7 days prior to treatments. Primary dopaminergic neurons were isolated at E18 and cultured as previously described [12]. …”

“…For immunofluorescence staining, N2A cells and primary neurons fixed and stained as previously described [12]. Primary antibodies used: rabbit polyclonal anti-Nurr1 (1:250; Santa Cruz, Dallas, TX), chicken polyclonal anti-Tyrosine Hydroxylase (1:500; Abcam, Cambridge, MA), rabbit polyclonal anti-Flag (1:500; Sigma F-7425).…”

How Is the Brain Renin–Angiotensin System Regulated?

“…49–53 In brain, PRR expression was reported to be increased by deoxycorticosterone acetate (DOCA)-salt through an Ang-II/AT1 receptor-dependent mechanism involving cAMP response element binding protein (CREB) and activator protein-1 (AP1). 54 …”