# Protein Regulation and Cytoskeletal Dynamics of Pulmonary Endothelial Barrier Function

> **NIH NIH K08** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2020 · $179,755

## Abstract

ABSTRACT
 Loss of pulmonary endothelial barrier function is responsible for the leakage of protein rich fluid from
the vascular space into the normally air filled alveoli which leads to hypoxemia, respiratory failure and
significant morbidity and mortality in patients with acute respiratory distress syndrome (ARDS). A major
determinant of this barrier function is cytoskeletal rearrangement and force generation which in turn alters cell
shape and membrane dynamics leading to intracellular gap formation. This proposal will mechanistically
characterize the functional roles of 3 critical cytoskeletal proteins that integrate to determine lung
endothelial cell (EC) permeability: non-muscle myosin light chain kinase (MLCK), an effector of
cytoskeletal rearrangement and force generation through its catalytic action in the ratcheting of actin-myosin
bonds; cortactin (CTTN), a multifunctional adapter and scaffolding protein which serves a regulatory role in
many dynamic cytoskeletal processes and is known to form a stable association with MLCK in areas of
peripheral actin polymerization and rearrangement in response to barrier protective stimuli; and the actin
related protein complex Arp 2/3, a key effector of actin polymerization and branching at these peripheral
sites that is known to interact with cortactin. The specific roles of these proteins and their interactions as part of
a complex in cytoskeletal dynamics are not yet fully characterized. Furthermore the consequence of
cytoskeletal dynamics on membrane kinetics and ultimately barrier integrity remains ill-defined in the
endothelium particularly in the lung vasculature. We hypothesize that CTTN, MLCK and Arp2/3 form
integrated complexes which regulate pulmonary EC cytoskeletal structure and membrane dynamics to
determine barrier function. This proposal will use complementary and sophisticated molecular, biochemical,
and imaging techniques to characterize the roles of these proteins and their interactions in regulating actin
structure. Specific Aim 1 will characterize the integrated roles of MLCK, CTTN and Arp 2/3 in generating
critical actin structures that regulate permeability in lung EC under conditions of barrier enhancement or
disruption. Specific Aim 2 will explore the functional consequences of these structures on membrane
dynamics and barrier integrity, employing novel MLCK constructs, mutated at the putative site of cortactin
binding as well as protein inhibitors and silencing RNA. Specific Aim 3 will use these novel reagents to
translate our observations to a pre-clinical model by characterizing the integrated functional effects of MLCK,
CTTN, and Arp2/3 in a murine model of LPS-induced acute lung injury (ALI). These studies will provide novel
mechanistic insights and an improved understanding of the cellular mechanisms of ALI/ARDS which will aid in
the development of new therapeutic targets to reverse or lessen the impact of these devastating pathologic
conditions on patients who suffer ...

## Key facts

- **NIH application ID:** 9851925
- **Project number:** 5K08HL135318-04
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** Patrick Belvitch
- **Activity code:** K08 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $179,755
- **Award type:** 5
- **Project period:** 2017-01-01 → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9851925

## Citation

> US National Institutes of Health, RePORTER application 9851925, Protein Regulation and Cytoskeletal Dynamics of Pulmonary Endothelial Barrier Function (5K08HL135318-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9851925. Licensed CC0.

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