# Membrane potential and Calcium Signaling in Neutrophil Development and Inflammation

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 2024 · $388,750

## Abstract

PROJECT SUMMARY
Neutrophils are essential for host defense against bacteria, however toxic neutrophil mediators such as
reactive oxygen radicals, granule enzymes and neutrophil extracellular traps contribute the pathogenesis of
acute and chronic inflammatory diseases. While the ability of neutrophils to phagocytose and kill pathogens
has been known for over 100 years, our knowledge of the molecular mechanisms guiding neutrophil activation
lags significantly behind that of other immune cells, precluding the development of strategic therapeutic
interventions targeting neutrophils. Our long-term goal is to define the mechanisms by which ion channels and
associated signaling pathways regulate neutrophil activation, and to leverage this knowledge to modify
disease. Calcium signals initiated via store-operated calcium entry (SOCE) are required for neutrophil
activation. The cell membrane potential directly influences influx of positively charged calcium ions. While the
functional role of the cell membrane potential has been extensively studied in excitable cells, little is known
about how the membrane potential modifies cellular processes in neutrophils in the context of development
and inflammation. This proposal is based on four fundamental observations from our laboratory: 1) ORAI1 and
ORAI2 calcium channels are critical for neutrophil SOCE and host defense during infection with S. aureus. 2)
Calcium responses in mouse neutrophils are heterogenous, with the magnitude of the calcium response
modulated in part by differential regulation of the cell membrane potential. 3) Expression of the calcium-
activated potassium channel KCa3.1 (Kcnn4) drives cell hyperpolarization and enhanced SOCE in a subset of
neutrophils. 4) The membrane potential-SOCE relationship is modulated during neutrophil development and
emergency granulopoiesis. Moreover, we have observed that a S. aureus pore-forming toxin manipulates the
neutrophil membrane potential and SOCE. Together these observations illustrate that the membrane potential
is a key modifier of calcium-dependent neutrophil function, and suggest that this pathway is a strategic target
of human pathogenic bacteria that secrete pore-forming cytotoxins to overcome host neutrophil defenses. The
objective of this proposal is to characterize the mechanisms by which membrane potential regulates SOCE
during neutrophil development and inflammation. We will test the central hypothesis that the membrane
potential is a critical modifier of neutrophil calcium signaling in mature neutrophils and homeostatic and
emergency granulopoiesis. In Aims 1 and 2 we will investigate the role of KCa3.1 in neutrophil SOCE and
calcium-dependent activation in mature and developing neutrophils. In Aim 3 we will expand these studies to
investigate how exogenous manipulation of the cell membrane potential by bacterial pore-forming toxins
disrupts calcium-dependent neutrophil function. The insight derived from these studies is anticipated to
engen...

## Key facts

- **NIH application ID:** 10728335
- **Project number:** 5R01AI166793-03
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Regina Clemens
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $388,750
- **Award type:** 5
- **Project period:** 2021-11-19 → 2026-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10728335

## Citation

> US National Institutes of Health, RePORTER application 10728335, Membrane potential and Calcium Signaling in Neutrophil Development and Inflammation (5R01AI166793-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10728335. Licensed CC0.

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