# Feedback and Crosstalk in Eukaryotic Chemotaxis

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 2021 · $326,077

## Abstract

Chemotaxis occurs during a number of key physiological events, including angiogenesis, embryonic
development and wound healing. It also contributes to disease progression in pathological conditions such as
cancer metastasis and arthritis. The goal of the current proposal is to reveal how biochemical reactions and
physical phenomena such as membrane deformation interact with one another in regulating chemotaxis.
Specifically, we will focus on elucidating the role of a superfamily of membrane deforming proteins,
Bin/Amphiphysin/Rvs (BAR), in distinct steps of chemotaxis. These steps include sensation of an extracellular
chemical gradient, cellular amplification of the input stimulus, polarization of intracellular signaling events, and
actuation of cell motility. For three BAR proteins that we already shown are involved in cell migration via gain-
and loss-of-function studies, we will precisely determine how each of these BAR proteins is required for
chemotaxis by performing biochemical and cell biological assays along with computational modeling.
 In particular, we execute the loss-of-function studies of the three BAR proteins to determine their role in
any one of the aforementioned steps of chemotaxis, with an emphasis on the polarization process by performing
chemotaxis and chemokinesis assays (Aim 1). We will then reveal the role of these BAR proteins specifically in
one of the core polarization programs, namely a positive feedback loop that is known to consist of several
signaling molecules (Aim 2). This will be achieved by conducting chemotaxis assays using both shallow and
steep chemical gradient, as well as an imaging-based assay we developed to quantitatively measure the extent
of feedback actuation. We also investigate sufficiency of BAR-induced membrane deformation in the positive
feedback using newly established tools that can deform membrane inside living cells within seconds. Collectively,
Aims 1 and 2 will characterize the crosstalk between biochemical and physical factors during the positive
feedback process that drives cell polarization. We will then reveal how BAR proteins mediate the cooperative
actuation of the positive feedback loop at a molecular level (Aim 3). Based both on previous reports and our own
recent findings, we hypothesize that signaling molecules such as PI3K can sense membrane curvature, and
therefore accumulates at local sites on the plasma membrane which have been bent by BAR proteins. To test
this hypothesis, we will perform two experiments: an in vitro liposome binding assay and a cell-based localization
assay. To further elucidate this non-intuitive, cooperative process on a quantitative level, parameters derived
from these wet experiments will be integrated into a computational model.
 Combined, the work outlined here represent powerful means by which we can explore crucial, but often
understudied, aspects of chemotaxis. More specifically, it will reveal the central role that membrane-deforming
proteins play...

## Key facts

- **NIH application ID:** 10207662
- **Project number:** 5R01GM123130-04
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Takanari Inoue
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $326,077
- **Award type:** 5
- **Project period:** 2018-09-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10207662

## Citation

> US National Institutes of Health, RePORTER application 10207662, Feedback and Crosstalk in Eukaryotic Chemotaxis (5R01GM123130-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10207662. Licensed CC0.

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