# Protein Disulfide Isomerase as Novel Redox Sensor in VEGF Signaling

> **NIH NIH R01** · AUGUSTA UNIVERSITY · 2020 · $380,000

## Abstract

Reactive oxygen species (ROS), such as H2O2 derived from NADPH oxidase (NOX) act as signaling molecules
to promote VEGF-induced angiogenesis in ECs and post-ischemic neovascularization. Fundamental question
remains “how diffusible H2O2 signal can be efficiently transmitted to promote therapeutic angiogenesis.”
Signaling function of ROS is through oxidation of reactive Cys residues to generate “Cysteine sulfenic acid (Cys-
OH)” which is involved in disulfide bond formation and redox signaling. Protein Disulfide Isomerase (PDI)
functions as oxidase, reductase and isomerase depending on redox environment. “PDIA1” is a major PDI isoform
with four reactive Cys residues in redox active domains. Given redox properties of PDI, PDI may function as
redox sensor in ROS-dependent VEGF signaling to enhance therapeutic angiogenesis and maintain endothelial
metabolic states. Preliminary Data found that PDIA1+/- mice or diabetes mice with reduced PDIA1 expression
show impaired reparative angiogenesis, indicating in vivo significance of PDIA1. In primary ECs, VEGF
stimulation increases Cys-OH formation of various proteins, which was markedly decreased by PDIA1 siRNA.
Experiments using 2D gel assay and searching for binding partner of PDIA1 discovered that PDIA1 functions as
a redox sensor in ROS-dependent VEGF signaling to promote Cys oxidation/activation of AMPK, a key regulator
of cell metabolism and angiogenesis, via disulfide bond formation. Moreover, in quiescent basal ECs, PDIA1
knockdown unexpectedly induced mitochondrial fragmentation and EC senescence without inducing ER stress
via increasing Cys oxidation of Drp1, a key fission GTPase. We thus hypothesize that PDIA1 functions as key
redox adaptor/reductase for Drp1 to maintain mitochondrial dynamics in quiescent ECs as well as redox
sensor when it is Cys oxidized to transduce VEGF-induced H2O2 signal to promote oxidative activation
of AMPK via disulfide bond formation, thereby enhancing endothelial metabolism and angiogenesis in
ECs. This is required for full neovascularization in ischemic vascular disease. Aim 1 will determine the
molecular mechanisms by which PDIA1 senses VEGF-induced H2O2 signal to promote EC metabolism and
angiogenesis via oxidative activation of AMPK, which is impaired in diabetic ECs. Aim2 will examine whether
PDIA1 maintains mitochondrial dynamics via binding to Drp1 to keep it in reduced/inactive state in quiescent
ECs, thereby preventing mitochondrial fragmentation and ECs dysfunction in diabetes. Aim 3 will determine the
in vivo role of endothelial PDIA1 in ROS-dependent reparative neovascularization, which is impaired in diabetes.
We will use biotin-labelled Cys-OH trapping probe; BiFC-based molecular protein interaction imaging;
mitochondrial dynamics imaging; EC-specific PDIA1-/- or diabetic mice; and gene transfer of EC-targeted Cys
oxidation defective mutants of PDIA1, AMPK and Drp1. Our proposal will provide novel insights into Cys
reduced/oxidized proteins and Cys oxida...

## Key facts

- **NIH application ID:** 9838782
- **Project number:** 5R01HL135584-05
- **Recipient organization:** AUGUSTA UNIVERSITY
- **Principal Investigator:** Masuko Ushio-Fukai
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $380,000
- **Award type:** 5
- **Project period:** 2016-12-12 → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9838782

## Citation

> US National Institutes of Health, RePORTER application 9838782, Protein Disulfide Isomerase as Novel Redox Sensor in VEGF Signaling (5R01HL135584-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9838782. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*