# On-demand neuronal condensate interactomes using new optogenomics tools

> **NIH NIH R21** · PRINCETON UNIVERSITY · 2022 · $202,500

## Abstract

PROJECT SUMMARY
Biomolecular condensates (BMCs) are emerging as a ubiquitous feature of compartmentalization
within cells. These structures can form by liquid-liquid phase separation of particular proteins and
RNAs from the rest of the cytoplasm or nucleoplasm and can perform important functions (e.g.
enzymatic reactions, signaling regulation). BMCs of the RNA-binding protein TDP-43 are
hypothesized to nucleate pathological aggregates and lead to neuron death in Amyotrophic
Lateral Sclerosis (ALS). However, BMCs are difficult to characterize with traditional techniques
because they lack membranes and can dissolve upon dilution and, therefore, are challenging (or
impossible) to purify. Additionally, interrogating toxic effects of disease-associated BMCs has
been problematic because of the difficulty of controlled induction of liquid-like or solid-like
condensates within neurons. Here, we propose the development of a new technology platform,
Phase-seq, that combines two approaches from different fields – biophysical in-cellulo
reconstitution of protein condensation and genomic mapping of RNA organization – to address
current methodological limitations for studying BMCs in neurons. This tool combines optogenetic
induction of BMCs in neurons (Corelets) with a cutting-edge genomics approach (SPRITE) to
interrogate the RNA compositions and functions of BMCs. First, we will lay the groundwork for
Phase-seq by establishing SPRITE in primary neurons to create a genome-wide map of RNA-
RNA interactions in these highly specialized cells and confirm that we can identify RNAs within
individual BMCs by inducing stress granules. We will then develop models of early and late stage
ALS pathology by inducing TDP-43 BMCs in neurons with Corelets, a new technology that allows
for controlled optogenetic induction of condensates with tight temporal and spatial resolution.
Finally, we will combine SPRITE and Corelets in neurons to create Phase-seq, a novel platform
for simultaneous induction of BMCs and characterization of their functions by mapping RNA
constituents. These experiments will allow us to gain valuable insight into RNA organization in
neuronal BMCs, determine how TDP-43 condensates may lead to neuron death, and identify
novel therapeutic avenues for ALS. We anticipate that the Phase-seq platform will be broadly
applicable for interrogating the functions of endogenous BMCs in neurons and the consequences
of aberrant BMCs in disease.

## Key facts

- **NIH application ID:** 10489500
- **Project number:** 1R21DA056345-01
- **Recipient organization:** PRINCETON UNIVERSITY
- **Principal Investigator:** Clifford P Brangwynne
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $202,500
- **Award type:** 1
- **Project period:** 2022-09-01 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10489500

## Citation

> US National Institutes of Health, RePORTER application 10489500, On-demand neuronal condensate interactomes using new optogenomics tools (1R21DA056345-01). Retrieved via AI Analytics 2026-06-27 from https://api.ai-analytics.org/grant/nih/10489500. Licensed CC0.

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