# Mechanisms of Claudin-5 Regulation during Neuroinflammation

> **NIH NS R01** · UNIVERSITY OF SOUTH FLORIDA · 2025 · $158,819

## Abstract

PROJECT SUMMARY
The blood-brain barrier (BBB) is a vital defender of the central nervous system (CNS) that allows for nutrient
exchange while blocking the entry of toxic factors or immune cells. However, its disruption is common in CNS
disorders and can drive their disease progression. As such, our long-term goals are to identify the mechanisms
governing BBB function and evaluate their therapeutic potential to preserve or restore BBB integrity and limit
disease progression. The overarching objective of this proposal is to investigate the role of FoxO1, nmMLCK,
and HDAC6 in BBB dysfunction and disease progression using animal and cell culture models of multiple
sclerosis (MS), a chronic CNS disorder affecting an estimated one million adults in the US. During barrier
maturation, the transcription factors FoxO1 and β-catenin are inactivated and removed from a silencer region in
the Cldn5 promoter. However, we have shown that inflammation-induced BBB-dysfunction requires their
concurrent re-activation and occupancy at the silencer region. This process involves nmMLCK. In a follow-up
study, we defined an insulin receptor (IR)-Akt2-FoxO1 axis that can be targeted with an IR agonist to limit FoxO1
activation, claudin-5 loss, and barrier dysfunction in BBB-ECs and mice induced with experimental autoimmune
encephalomyelitis (EAE), a model of MS. Here, we provide preliminary data showing the importance of nmMLCK
and its regulation by histone deacetylase 6 (HDAC6) in barrier dysfunction. Global knockout mice are resilient to
EAE, including paralysis, BBB dysfunction, and claudin-5 loss. In tandem, we explored mechanisms for nmMLCK
activation and identified that it is robustly deacetylated in IL-1ꞵ-stimulated BBB-ECs. Using inhibitors, we found
that tubastatin A attenuated barrier dysfunction, implying that HDAC6 is responsible. Thus, we hypothesize that
FoxO1 and β-catenin are essential for mediating inflammation-induced claudin-5 repression, driving BBB
dysfunction. To addres

## Key facts

- **NIH application ID:** 11504904
- **Project number:** 7R01NS143814-02
- **Recipient organization:** UNIVERSITY OF SOUTH FLORIDA
- **Principal Investigator:** Richard Scott Beard
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NS
- **Fiscal year:** 2025
- **Award amount:** $158,819
- **Award type:** 7
- **Project period:** 2025-08-01T00:00:00 → 2030-07-31T00:00:00

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11504904

## Citation

> US National Institutes of Health, RePORTER application 11504904, Mechanisms of Claudin-5 Regulation during Neuroinflammation (7R01NS143814-02). Retrieved via AI Analytics 2026-05-19 from https://api.ai-analytics.org/grant/nih/11504904. Licensed CC0.

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