# Purinergic Regulation of Veinous Endothelial Permeability

> **NIH NIH R01** · UNIVERSITY OF VIRGINIA · 2021 · $512,408

## Abstract

|| ABSTRACT
Breakdown of the endothelial cell barrier is considered a defining pathological hallmark of multiple diseases.
Indeed, sepsis accounts for more hospital deaths per year than any other condition in the United States, and
the disease is currently devoid of any targeted pharmacological intervention. Critical to understanding how
inflammation affects vascular barrier function is that endothelial cells throughout the circulatory system are not
homogenous. Inflammation specifically affects vascular permeability through effects on the venous
endothelium, whereas the arterial endothelium is not susceptible to inflammation-induced permeability and
instead primarily regulates blood pressure and angiogenesis. Thus, a mechanistic view of how venous
endothelial barrier function is regulated is essential to human health and disease. Our current understanding
of vascular barrier function does not account for endothelial heterogeneity and the unique cell adhesion and
signaling pathways specific to each endothelial cell type. Purinergic signaling has been identified as a key
regulator of endothelial permeability; however the means by which purine nucleotides are brought into and
affect the local environment has never been identified. We hypothesize that venous endothelial barrier
function is regulated by a localized purinergic signaling cascade that controls the stability and expression of
tight junction proteins. We will use three aims to test this concept. In Aim 1, we will determine roles for
Pannexin 1 in regulating venous endothelial permeability. This aim will use novel methods for ex vivo vein
isolation and measure transendothelial resistance and dye movement from endothelial cell specific Panx1
knockout mice and endothelial cell specific Panx1 over-expressing mice, as well in vivo testing using the cecal
ligation puncture (CLP) septic model. In Aim 2, we will measure the relative contributions of different
Adenosine Receptors (ARs) on endothelial barrier function. We will determine the differential role of
CD39 and CD73 on adenosine receptor activation, using endothelial cell specific A2A and A2B floxed mice, as
well as the relative contribution of PKA or PKC upon activation. Lastly, in Aim 3, we will define roles for
claudin-11 in venous endothelial barrier function and as a target for TRPV4-mediated disruption of
tight junctions. This aim will utilize state of the art calcium imaging to determine a role for TRPV4 in
regulation of claudin-11 production, trafficking, assembly and stability. Claudin-11 is a novel claudin isoform
whose role in barrier function is only beginning to be elucidated. Molecular manipulation of claudins will be
used to demonstrate that claudin-11 is required for veins to be sensitive to calcium fluxes because it has the
unique capacity to bind calmodulin, whereas claudin-5 does not. The feasibility of accomplishing these aims is
underscored by all proposed knockout mice being in hand, an IRB in place for human samples,...

## Key facts

- **NIH application ID:** 10111551
- **Project number:** 5R01HL137112-04
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **Principal Investigator:** Brant E Isakson
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $512,408
- **Award type:** 5
- **Project period:** 2018-02-18 → 2022-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10111551

## Citation

> US National Institutes of Health, RePORTER application 10111551, Purinergic Regulation of Veinous Endothelial Permeability (5R01HL137112-04). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10111551. Licensed CC0.

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