# Calcium microdomains regulating pulmonary endothelial permeability

> **NIH NIH P01** · UNIVERSITY OF SOUTH ALABAMA · 2020 · $365,347

## Abstract

PROJECT SUMMARY
We have previously identified distinct functional outcomes in lung alveolar septal endothelium on activation of
TRPV4, a Ca channel in the vanilloid transient receptor potential family, or the 1G T-type voltage-gated Ca
2+ 2+
channel. Despite equivalent whole-cell Ca2+ transients in the extremely thin septal endothelium, TRPV4 only
increases endothelial permeability while the T-channel only increases endothelial surface expression of P-
selectin. As a result, we propose a critical paradigm shift, from a global perspective of Ca2+-dependent
signaling to one where Ca2+ microdomains, orchestrated by mitochondrial-dependent Ca2+ buffering, are
organized to yield discrete functional outcomes within lung microvascular endothelial cells. Our preliminary
data suggest discrete localization of these Ca2+channels and distribution of mitochondria even into the
attenuated cell periphery in lung microvascular endothelium in situ. Further, we have documented that
mitochondrial bioenergetic dysfunction leads to loss of domain constraints with greater spread and duration of
TRPV4-mediated Ca2+ transients and increased endothelial permeability in lung microvascular endothelium.
Collectively, these observations led us to the HYPOTHESIS that in lung microvascular endothelium,
mitochondrial Ca2+ buffering constrains Ca2+ influx via TRPV4 or the T-type channel to spatially delimited
cytosolic microdomains yielding specificity of functional outcomes, constraints lost with mitochondrial
dysfunction. Our SPECIFIC AIMS are to: 1) determine the contribution of mitochondria to buffering of the
spatial spread, dynamics and functional specificity of Ca2+ signals on activation of TRPV4 or T-type Ca2+
channels, and 2) determine the extent to which mitochondrial bioenergetic dysfunction decreases the threshold
for and specificity of functional outcomes on activation of TRPV4 or T-type Ca2+ channels. We will utilize
innovative high-speed hyperspectral excitation scanning imaging and novel analytical tools to detect and
interpret signal dynamics with high spatial and temporal resolution. These data will be interpreted in context of
localized functional outcomes, in naïve endothelium, in endothelium after disruption of mitochondrial-
dependent buffering and after initiation of mitochondrial bioenergetic dysfunction in the intact lung with
hyperoxia and Pseudomonas aeruginosa-induced sepsis. We predict that such dysfunction will lead to blurring
of specificity for Ca2+ signaling, altering the set point from which lung endothelium interprets Ca2+ signaling with
mechanical stress. This work will provide the first insight into mechanisms underlying Ca2+ microdomains in
lung microvascular endothelium. To accomplish this, we have assembled an outstanding team with expertise
spanning from structural and functional determinants of endothelial permeability, development and use of novel
tools, and modeling of signaling domains/networks to bioenergetics and sepsis.

## Key facts

- **NIH application ID:** 9962993
- **Project number:** 5P01HL066299-18
- **Recipient organization:** UNIVERSITY OF SOUTH ALABAMA
- **Principal Investigator:** MARY I TOWNSLEY
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $365,347
- **Award type:** 5
- **Project period:** — → —

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9962993

## Citation

> US National Institutes of Health, RePORTER application 9962993, Calcium microdomains regulating pulmonary endothelial permeability (5P01HL066299-18). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9962993. Licensed CC0.

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