Project Summary/Abstract
Maintenance of neurovascular health is critical for a properly functioning central nervous system (CNS).
Neurovascular disorders not only affect the CNS vasculature – accompanying damage to CNS tissue can lead
to neurological dysfunction, compromised quality of life, and even death. Brain arteriovenous malformation
(AVM) is a human neurovascular disease characterized by enlarged, tortuous, often tangled vessels that shunt
blood directly from artery to vein and promote abnormally high-velocity and high-pressure blood flow. Effective
clinical treatments for brain AVM are limited to invasive surgical procedures; thus, there is a critical need for
prevention and treatment strategies that can be delivered to patients pharmacologically. Recent sequencing
data from a mouse model of brain AVM and from human brain AVM tissue independently showed increased
Adrenomedullin (encodes a secreted vasodilatory peptide) expression in endothelial cells (ECs) from brain
AVM, as compared to controls. This proposal will test whether inhibition of Adrenomedullin signaling, using a
small molecule inhibitor in vivo and in vitro, can prevent EC abnormalities and features of brain AVM.
We will use in vivo and in vitro approaches to examine whether Adrenomedullin signaling is required for
vascular abnormalities associated with Rbpj-deficient brain AVM in mice and for cellular perturbations caused
by RBPJ deficiency in cultured human brain ECs. The rationale is as follows: (i-ii) using a genetically inducible
mouse model of brain AVM (endothelial deletion of Rbpj from postnatal day (P) 1) and an siRNA based in vitro
system for cultured human brain ECs (si-RBPJ), we recently showed that endothelial Rbpj/RBPJ deficiency
upregulates Adrenomedullin in both mouse (isolated at P14) and human brain ECs; (iii) we showed that Rbpj
occupies chromatin regions mapping to Adrenomedullin, suggesting that Adrenomedullin is a direct binding
target of Rbpj; (iv) published sequencing data from another lab showed increased Adrenomedullin expression
in human brain AVM tissue. We will test the hypothesis that pharmacological inhibition of Adrenomedullin
signaling prevents molecular and cellular abnormalities, including those that contribute to brain AVM, in
Rbpj/RBPJ-deficient brain ECs. This hypothesis will be addressed in two specific aims that will determine
whether inhibition of Adrenomedullin signaling, via in vivo or in vitro administration of the small-molecule
inhibitor NSC16311, (Aim 1) attenuates brain AVM formation in endothelial-Rbpj deficient mice and (Aim 2)
prevents cellular abnormalities in cultured, RBPJ-deficient human brain ECs.
These studies will advance our long-term research objectives, which are to understand molecular and
cellular mechanisms of brain AVM pathogenesis, including how different signaling molecules are involved, and
to identify molecular targets that may lead to new, highly effective, pharmacologically based treatments for
brain AVM. Our hope is to offer therapeutic options that alleviate symptoms of brain AVM, including
neurological complications associated with this neurovascular disease.
