Angiotensin II regulates ACE and ACE2 in neurons through p38 mitogen-activated protein kinase and extracellular signal-regulated kinase 1/2 signaling

Abstract

Brain ANG II plays an important role in modulating sympathetic function and homeostasis. The generation and degradation of ANG II are carried out, to a large extent, through the angiotensin-converting enzyme (ACE) and ACE2, respectively. In disease states, such as hypertension and chronic heart failure, central expression of ACE is upregulated and ACE2 is decreased in central sympathoregulatory neurons. In this study, we determined the expression of ACE and ACE2 in response to ANG II in a neuronal cell culture and the subsequent signaling mechanism(s) involved. A mouse catecholaminergic neuronal cell line (CATH.a) was treated with ANG II (30, 100, and 300 nM) for 24 h, and protein expression was determined by Western blot analysis. ANG II induced a significant dose-dependent increase in ACE and decrease in ACE2 mRNA and protein expression in CATH.a neurons. This effect was abolished by pretreatment of the cells with the p38 MAPK inhibitor SB-203580 (10 M) 30 min before administration of ANG II or the ERK1/2 inhibitor U-0126 (10 M). These data suggest that ANG II increases ACE and attenuates ACE2 expression in neurons via the ANG II type 1 receptor, p38 MAPK, and ERK1/2 signaling pathways.angiotensin; converting enzyme; signaling THE RENIN-ANGIOTENSIN SYSTEM (RAS) in the brain plays an important role in the regulation of blood pressure, water balance, and endocrine secretion. Functional studies have clearly established that augmented ANG II and ANG II type 1 receptor (AT 1 R) signaling in the central nervous system plays an essential role in the sympathoexcitation in disease states such as hypertension and chronic heart failure in various animal models (43). Elevated plasma ANG II can directly activate neurons in the circumventricular organs, which lack a tight blood-brain barrier (6). On the other hand, other brain regions, such as the presympathetic neurons in the paraventricular nucleus (PVN) and rostral ventrolateral medulla, do not have direct access to systemic ANG II but have also been associated with an upregulation of local ANG II signaling in disease states (44).The conversion of bioactive angiotensin peptides is mainly carried out by two angiotensin-converting enzymes: angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2). ACE catalyzes the conversion from ANG I to the major sympathoexcitatory peptide ANG II, while ACE2 primarily metabolizes ANG II to form ANG-(1-7). ANG-(1-7) exhibits effects that are counter to the effects of ANG II through activation of the Mas receptor (30,32). ACE also mediates the degradation of ANG-(1-7) to form the nonactive peptide ANG-(1-5) (7). Therefore, a balance between ACE and ACE2 expression and activity may contribute to the control of sympathetic nerve activity. Reciprocal changes in ACE and ACE2 expression in brain autonomic regions have been shown in studies using different models of heart failure (13, 34). Similarly, an increase in the ratio of ACE to ACE2 has been observed in the brain (1) and kidneys (36) in hypertensive patients and anim...

Activation of the Neuroprotective Angiotensin-Converting Enzyme 2 in Rat Ischemic Stroke

“…It has been reported that Ang II levels are increased in the stroke cortex one day after stroke 23 , and others have shown Ang II to upregulate ACE, AT1R, and TACE, and decrease ACE2 expression 24, 25 , which might account for some of the changes that we have observed one day post-stroke (Fig. 1C, Fig.…”

Pirfenidone controls the feedback loop of the AT1R/p38 MAPK/renin-angiotensin system axis by regulating liver X receptor-α in myocardial infarction-induced cardiac fibrosis

“…AT1R/p38 MAPK, an important signalling pathway, is involved in pancreatic fibrosis, renal tubulointerstitial fibrosis, and peritoneal fibrosis. Moreover, previous studies have reported that activation of the AT1R/p38 MAPK pathway induces an imbalance in the ACE/ACE2 ratio in HK-2 cells and neurons78.…”

“…Recent studies have suggested the involvement of the AT1R/p38 MAPK pathway in pancreatic fibrosis5, renal tubulointerstitial fibrosis6, and peritoneal fibrosis7. Importantly, the AT1R/p38 MAPK pathway also affects the RAS by modulation of the ACE/ACE2 ratio8. These findings indicate a regulatory mechanism that operates between the AT1R/p38 MAPK pathway and RAS in the development of fibrotic disease.…”

Brain-Targeted Angiotensin-Converting Enzyme 2 Overexpression Attenuates Neurogenic Hypertension by Inhibiting Cyclooxygenase-Mediated Inflammation

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