# Excitable Networks in Directed Cell Migration

> **NIH NIH R35** · JOHNS HOPKINS UNIVERSITY · 2022 · $1,080,750

## Abstract

We are investigating molecular mechanisms of directed cell migration, a critical process in health and
disease, using Dictyostelium as a discovery tool to inform our studies of neutrophils, macrophages, and
epithelial cells. At the core of our working model are coupled Signal Transduction and Cytoskeletal
Excitable Networks, referred to as STEN and CEN which drive motility. The STEN integrates inputs from
directional sensing and polarity networks to bring about directed migration. In the last grant period, we
found that protrusions are governed by waves of coupled STEN-CEN activities and that manipulation of
negatively charged lipids on the inner face of the membrane can alter network excitability and control cell
behavior. The STEN-CEN concept is conserved in mammalian cells and the networks are hyperactivated
in transformed cells, augmenting motility and macropinocytosis. Since these processes require geranyl
geranylation, statins cause starvation of cancer cells. Finally, we found that vesicles internalized from
retracting protrusions carry “back” components to the rear of the cell contributing to polarity.
How do diverse cellular protrusions depend on the setpoint/threshold of STEN-CEN? We are
combining imaging, synthetic biological, and computational studies to prove that pseudopods,
lamellipods, forming phagosomes, and so on are closely related on a spectrum and interconvertible. We
will show that spatiotemporal patterns of activities and responses to acute molecular perturbations are
consistent across these protrusions and parallel those established in propagating STEN-CEN waves.
What explains the extraordinary coordination of activities in STEN and CEN? Surmising that charge on
the inner leaflet of the membrane is an organizer, we are 1) designing methods to directly monitor charge
in local regions; 2) determining how anionic lipids transiently decrease; 3) manipulating charge locally
with optogenetic systems; 4) examining how the location of key proteins is regulated by surface charge.
Is lowered STEN threshold a general property of transformed cells and can it be exploited? To address
this question, we are 1) comparing threshold indicators, such as propagating waves, with
macropinocytosis and statin sensitivity in a series of increasingly metastatic cell lines and organoids; 2)
identifying the essential geranylgeranylated proteins in STEN; 3) genetically engineering cells to increase
threshold to normalize cancer cells or further decrease threshold to induce cell death.
How does control of STEN and CEN at the cell poles mediate directional sensing and polarity? First,
using a novel suppression assay, we are screening kinase and substrate deficient cells to identify global
inhibitors. Second, we are studying membrane flow in a variety conditions to pursue our “reverse
fountain” model and it reconcile with alternate models that argue membrane flows from front to back.
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## Key facts

- **NIH application ID:** 10399587
- **Project number:** 5R35GM118177-07
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Peter N Devreotes
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $1,080,750
- **Award type:** 5
- **Project period:** 2016-05-01 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10399587

## Citation

> US National Institutes of Health, RePORTER application 10399587, Excitable Networks in Directed Cell Migration (5R35GM118177-07). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10399587. Licensed CC0.

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