# LRRC8 complex regulation of endothelial function

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 2024 · $555,801

## Abstract

Project Summary
The endothelium responds to a multitude of chemical and mechanical factors in regulating vascular tone,
angiogenesis, blood pressure and blood flow. The endothelial volume regulatory anion channel (VRAC) has
been proposed to be mechano-sensitive, to activate in response to fluid flow/hydrostatic pressure and putatively
regulate vascular reactivity and angiogenesis. We recently reported that the Leucine Rich Repeat Containing
Protein 8a, LRRC8a (LRRC8A) is a required component of the heterohexameric complex that forms VRAC in
human umbilical vein ECs (HUVECs). Endothelial LRRC8A regulates AKT-eNOS and mTOR signaling under
basal conditions, and with stretch and shear-flow stimulation and is required for EC alignment to laminar shear
flow. Endothelium-restricted LRRC8A KO (LRRC8A KO) mice have impaired endothelium-dependent vascular
relaxation, develop hypertension in response to chronic angiotensin II infusion and exhibit impaired retinal blood
flow with both diffuse and focal blood vessel narrowing in the setting of Type 2 diabetes (T2D). These data
demonstrate that LRRC8a regulates AKT-eNOS, and mTOR signaling in endothelium and is required for
maintaining vascular function. There remains a knowledge gap in (a) the molecular identity of specific
LRRC8 heteromers that form VRAC in endothelium, (b) the molecular mechanisms that connect the
endothelial LRRC8 complex to AKT-eNOS and mTOR signaling, (c) the therapeutic potential of small
molecules targeting the LRRC8 complex needs to be evaluated, leading to a novel class of compounds
to improve vascular function and hypertension in metabolic syndrome.
We have biochemical, patch-clamp and imaging evidence that LRRC8 channel complexes are expressed and
functional in lysosomes (Lyso-LRRC8) and have identified a critical channel pore mutation (R103E) that
specifically disrupts LRRC8 channel activity. Given that lysosomes are signaling hubs that integrate nutrient
sensing and AKT-mTOR signaling, we hypothesize LRRC8A/C channels co-regulate plasma membrane
PI3K-AKT signaling and lysosome centered mTOR signaling in endothelium, and that small molecule
LRRC8 complex modulators can restore dysfunctional endothelial LRRC8A/C in diabetes associated
vascular disease and hypertension. To test the above hypotheses, we propose three specific AIMs that
develop endothelial LRRC8 biology from molecular signaling mechanisms to proof of concept in vivo therapeutic:
AIM#1: Delineate the mechanisms of plasma membrane versus lysosomal LRRC8 signaling to AKT-
mTOR signaling in endothelium.
AIM#2: Examine LRRC8 molecular contributions to EC function in vitro, ex vivo and in vivo
AIM#3: Examine the therapeutic efficacy of small molecule LRRC8 modulators to improve vascular
function and blood pressure in diabetes associated hypertension models

## Key facts

- **NIH application ID:** 10817142
- **Project number:** 5R01HL168600-02
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Abhinav Diwan
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $555,801
- **Award type:** 5
- **Project period:** 2023-04-01 → 2027-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10817142

## Citation

> US National Institutes of Health, RePORTER application 10817142, LRRC8 complex regulation of endothelial function (5R01HL168600-02). Retrieved via AI Analytics 2026-06-04 from https://api.ai-analytics.org/grant/nih/10817142. Licensed CC0.

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