# A New Phase of Wnt: Interrogating a Thermodynamic Signaling Node Using Optogenetics

> **NIH NIH F31** · UNIVERSITY OF CALIFORNIA SANTA BARBARA · 2021 · $46,036

## Abstract

Project Summary:
Developing and adult cells are informed of their identity and given behavioral instructions through patterns of
secreted morphogens. The Wnt pathway is an important morphogenic signaling pathway, directing proliferation
and differentiation of stem cells, during both embryogenesis and regeneration of neural and intestinal tissues in
adulthood. Wnt inputs are transduced into behavioral responses via spatiotemporal expression of the
transcription factor β-catenin (β-cat), but the mechanisms for the cell’s regulation of β-cat are unclear. For this
reason, perturbations to the pathway are often unpredictable and no effective therapeutics targeting abnormal
Wnt pathway activation yet exist. β-cat is degraded by an oligomeric membrane-less organelle, the Destruction
Complex (DC), whose function is related to its ability to form mesoscale, liquid protein droplets. Thermodynamic
disruption of DC liquid-liquid phase separation (LLPS)—either dissolution or solidification of droplets—results in
aberrant signaling, suggesting that the DC transduces Wnt input via a change in its material state. Due to a lack
of tools for controlling DC LLPS and measuring its signaling output, the ‘thermodynamic DC’ model of Wnt
signaling remains untested. The objective of this proposal is to determine if and how DC thermodynamic state
transduces Wnt input into β-cat spatiotemporal expression. I will construct an in vivo phase diagram of the DC
using inducible scaffold expression and optogenetic clustering to determine whether DC LLPS changes in
response to Wnt input and/or gates downstream signal output. I will use a photo-switchable tag to track
endogenous β-cat degradation and DC component localization as cells receive Wnt ligand, determining the
timescales and dynamic range of DC output change in response to signaling input. Finally, I will use optogenetic
proximity labeling and exosome secretion to determine how the interactomes of DC scaffolds change in response
to Wnt input. The proposed work will yield an input/output understanding of the intracellular Wnt pathway and
the first effort to directly understand the role of LLPS in live-cell signaling dynamics in general. A model of Wnt
signaling that includes thermodynamic properties of the DC will both inform our understanding of how phase
separation is used to make cell fate decisions and guide future therapeutic strategies leveraging LLPS.

## Key facts

- **NIH application ID:** 10313754
- **Project number:** 1F31HD106900-01A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA SANTA BARBARA
- **Principal Investigator:** Ryan Lach
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $46,036
- **Award type:** 1
- **Project period:** 2021-07-07 → 2024-07-06

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10313754

## Citation

> US National Institutes of Health, RePORTER application 10313754, A New Phase of Wnt: Interrogating a Thermodynamic Signaling Node Using Optogenetics (1F31HD106900-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10313754. Licensed CC0.

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