# Actin gating of crosstalk between Rho GTPases in cell migration

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2024 · $226,623

## Abstract

PROJECT SUMMARY/ABSTRACT
Persistent cell migration is fundamental for immune responses, development, and the dissemination of cancer
cells. This migration requires the establishment and maintenance of stable cell polarity, even while a cell
integrates noisy heterogeneous cues from its environment. To achieve this, Rho family GTPases act as central
hubs that organize signaling cascades and cytoskeletal rearrangements into subcellular domains. Feedback and
crosstalk connections are thought to be central to this pattern-forming ability. However, the wiring of this circuit
is still incompletely understood, and there are major gaps in our understanding of how negative regulators limit
and separate spatial domains. Determining these molecular connections in migrating leukocytes would identify
new therapeutic targets for treating inflammation and would be broadly relevant for understanding Rho GTPase
function in many cell types and biological processes. Major obstacles to progress have been the fast timescale
and inherently spatial nature of the signaling system. To address these challenges, we have developed new
molecular tools that allow us to control the activity of individual key components with light while measuring the
response of a second component with subcellular resolution in live single cells. Our preliminary results indicate
that in addition to acting as outputs to move the cell, different actin assemblies are intimately involved in the
biochemical wiring of Rho GTPase crosstalk. We have identified an “actin-gated” crosstalk connection between
RhoA and Cdc42, and we have identified the protein Arhgap30 as a previously unappreciated primary regulator
of Cdc42 that is critical for polarization and migration in leukocytes. We hypothesize that different actin
assemblies act as scaffolds to localize regulators of Rho GTPase crosstalk, creating subcellular zones with
distinct signal wiring to promote stable cell polarity. Specifically, we aim to 1) determine how branched actin
assembly regulates Cdc42 and RhoA activities in leukocyte cells, 2) determine how the local actin network
structure controls crosstalk between RhoA and Cdc42, and 3) determine the regulation and role of Arhgap30 in
crosstalk and polarity signaling. Our approach will combine new tool sets for optical control of signaling and
cytoskeletal components with simultaneous measurement of actin assemblies and Rho GTPase activities in
single cells. In combination, we will use chemical perturbations, mutational analysis, and biochemical
approaches to characterize molecular connections. Our long-term goals are to determine how reciprocal
regulation between actin and Rho GTPases creates robust polarity in multiple cell types, including leukocytes
and disseminating cancer cells. The proposed research will advance our basic understanding of how biochemical
signaling pathways both generate and stabilize subcellular domains to control behaviors such as cell migration.

## Key facts

- **NIH application ID:** 11036033
- **Project number:** 3R01GM148769-01A1S1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Sean Ryan Collins
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $226,623
- **Award type:** 3
- **Project period:** 2023-07-25 → 2027-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11036033

## Citation

> US National Institutes of Health, RePORTER application 11036033, Actin gating of crosstalk between Rho GTPases in cell migration (3R01GM148769-01A1S1). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/11036033. Licensed CC0.

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