# Regulation of Chemotactic Signaling

> **NIH NIH R35** · JOHNS HOPKINS UNIVERSITY · 2022 · $409,375

## Abstract

Summary
Chemotactic cell migration underlies embryonic development, wound healing and immune responses.
Furthermore, aberrant chemotaxis leads to chronic inflammatory disease and tumor metastasis. My laboratory
has long been interested in signaling mechanisms that control cell behaviors in chemotaxis. In a chemical
gradient, cells polarize intracellular signaling and migrate toward chemoattractants. Ligand binding to
chemoattractant receptors selectively activates two kinases, TORC2 and PI3K, at the front of cells. TORC2
and PI3K are the master kinases that induce cytoskeletal remodeling to extend pseudopods and function
immediately downstream of chemotactic receptors. Polarized activation of these two kinases is essential
for creating the leading edge of cells that migrate in a chemical gradient. Despite the critical relevance to
basic and medical science, an understanding of the spatial and temporal regulation of TORC2 and PI3K
remains incomplete. An overarching challenge is to decipher how the TORC2 and PI3K signaling pathways
are regulated at the front versus the back of cells in a chemical gradient.
To explore mechanisms that regulate the TORC2 pathway, we will take advantage of our recently developed
biochemical systems. In these systems, chemoattractant-regulated activation and inhibition of TORC2 are
faithfully reconstituted with purified TORC2 and two small GTPases, Rho and Ras. These new assays will
identify the biochemical and biophysical mechanisms that create distinct chemotactic signaling at the leading
and trailing edges of migrating cells. The mechanistic principle that is determined will be tested and translated
in our cellular reconstitution systems using knockout cell lines expressing WT and mutant TORC2 and its
regulatory components. Using live-cell imaging with FRET microscopy and single-molecule microscopy, we will
place the signaling principle in a spatial and temporal context in migrating cells. For the PI3K pathway, we will
analyze proteins that control the localization of the PIP3 phosphatase PTEN to the plasma membrane at the
back of cells. The rear localization of PTEN enables PIP3 signaling activation at the leading edge and its
inhibition at the trailing edge. We will also determine the function of the identified mechanisms that control
PTEN localization in tumorigenesis and metastasis in mouse xenograft models expressing engineered PTEN
molecules with altered localization. These studies will elucidate the fundamental logics by which
polarization of intracellular signaling is established in cells during chemotactic migration and the
physiological importance of this signaling in vivo.

## Key facts

- **NIH application ID:** 10377388
- **Project number:** 5R35GM131768-04
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Miho Iijima
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $409,375
- **Award type:** 5
- **Project period:** 2019-06-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10377388

## Citation

> US National Institutes of Health, RePORTER application 10377388, Regulation of Chemotactic Signaling (5R35GM131768-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10377388. Licensed CC0.

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