Conditional deletion of Rcan1 predisposes to hypertension-mediated intramural hematoma and subsequent aneurysm and aortic rupture

Abstract

Aortic intramural hematoma (IMH) can evolve toward reabsorption, dissection or aneurysm. Hypertension is the most common predisposing factor in IMH and aneurysm patients, and the hypertensive mediator angiotensin-II induces both in mice. We have previously shown that constitutive deletion of Rcan1 isoforms prevents Angiotensin II-induced aneurysm in mice. Here we generate mice conditionally lacking each isoform or all isoforms in vascular smooth muscle cells, endothelial cells, or ubiquitously, to determine the contribution to aneurysm development of Rcan1 isoforms in vascular cells. Surprisingly, conditional Rcan1 deletion in either vascular cell-type induces a hypercontractile phenotype and aortic medial layer disorganization, predisposing to hypertension-mediated aortic rupture, IMH, and aneurysm. These processes are blocked by ROCK inhibition. We find that Rcan1 associates with GSK-3β, whose inhibition decreases myosin activation. Our results identify potential therapeutic targets for intervention in IMH and aneurysm and call for caution when interpreting phenotypes of constitutively and inducibly deficient mice.

Aortic disease in Marfan syndrome is caused by overactivation of sGC-PRKG signaling by NO

“…NO signaling pathway activation dysregulates actin cytoskeleton dynamics in MFS VSMCs. To investigate whether the NO-sGC-PRKG signaling pathway is activated in MFS, we measured VASP-S239 phosphorylation (pVASP-S239) as a readout of PRKG activity 30 in primary aortic VSMCs from wildtype (WT) mice 31,32 and a mouse model of MFS (Fbn1 C1039G/+ mice) 33 cultured in the presence of inhibitors of NOS (L-NAME), sGC (ODQ), and PRKG (KT5823) (Fig. 1a).…”

“…Blood pressure measurements. Arterial blood pressure (BP) was measured in mouse tails using the automated BP-2000 Blood Pressure Analysis System and software (Visitech Systems, Apex, NC, USA) 32,76 . BP measurements were recorded in mice located in a tail-cuff restrainer over a warmed surface (37°C).…”

RCAN1 in cardiovascular diseases: molecular mechanisms and a potential therapeutic target

“…First, AngII induces IMH and contributes to aneurysm formation in the ascending and the abdominal aorta in animal models (Rateri et al 2014 ), while NFAT activation and increased RCAN1.4 expression are induced by AngII in the aorta (Esteban et al 2011 ). Moreover, the conditional deletion of Rcan1 in smooth muscle cells (SMCs) or endothelial cells (ECs) disrupts aortic wall homeostasis, predisposing the aorta to hypertension-induced IMH, and subsequent aneurysm and rupture (Villahoz et al 2018 ). Rho kinase (ROCK)-mediated myosin light chain (MLC) phosphorylation plays important roles in various cellular processes such as cellular morphogenesis, motility, and smooth muscle contraction, thus, ROCK hyper-activation-induced sustained MLC phosphorylation may contribute to the pathogenesis of vascular remodeling-related diseases(Kaneko-Kawano et al 2012 ).…”

“…RCAN1 is proved to inhibit the activity of GSK3β. The loss of GSK3β inhibition in conditional RCAN1 −/− cells promotes ROCK activation and subsequently increases MLC phosphorylation, which further alters aortic wall structure and predisposes to IMH and aortic rupture (Villahoz et al 2018 ). These results indicate that the maintenance of RCAN1 level and activity is beneficial for the prevention or treatment of IMH.…”

“…Mounting evidence indicates that RCAN1 exerts different effect in various CVDs. RCAN1 reduction is beneficial to atherosclerosis (Mendez-Barbero et al 2013 ) whereas RCAN1 protects against myocardial ischemia/reperfusion injury (Rotter et al 2014 ), myocardial hypertrophy (Sussman et al 1998 ) and intramural hematoma /aortic rupture (Villahoz et al 2018 ). Moreover, growing evidence indicates that RCAN1 is dysregulated in CVDs.…”