# Cell Organization Through Phase Separation:  Mechanisms, Functions and Disease

> **NIH NIH R35** · UT SOUTHWESTERN MEDICAL CENTER · 2022 · $369,000

## Abstract

Biomolecular condensates concentrate select groups of macromolecules into discrete foci in eukaryotic cells
in the absence of a surrounding membrane. Condensates are found throughout eukaryotic cells, and function
in processes ranging from signal transduction to RNA metabolism to gene expression. Aberrant condensates
have been implicated in neurodegeneration, cancer and skin diseases. Our understanding of eukaryotic cell
organization was transformed by the discovery that many condensates appear to form through liquid-liquid
phase separation (LLPS) of multivalent macromolecules. My lab played an important part in this discovery by
establishing key principles, including the essential role of multivalent interactions in promoting biological
LLPS, the regulation of LLPS by covalent modifications, and the ability of LLPS to increase enzymatic
activity. In recent years, we showed that and how LLPS can produce membrane-associated clusters that
increase the specific activity of signaling molecules. We also showed that intrinsically disordered regions of
proteins (IDRs) can undergo LLPS to produce liquid droplets that harden to solids over time, likely due to
formation of amyloid filaments, and that misregulated hardening may contribute to neurodegeneration.
Further, we proposed the first model to explain condensate composition based on a scaffold/client framework.
Most recently, we showed that chromatin has an intrinsic propensity to undergo LLPS, providing a new view
of eukaryotic genome organization. Here, we propose a broad program to address leading questions in the
biomolecular condensate field. We will use microfluidics to assess LLPS of thousands of IDRs in a single
experiment, leading to a predictive model for the sequence determinants of LLPS and amyloid formation by
IDRs. This work will deepen our biophysical understanding of these processes, predict which IDRs are likely
to contribute to specific biological processes (e.g. transcription) through self-assembly, and reveal how IDR
mutations lead to disease through amyloid formation. We will also examine how individual components of
yeast P bodies impact the LLPS threshold and composition of the compartments and how RNA helicase and
RNA decapping activities are modulated within them. This work will lead to a new model of condensate
composition based on the patterns of interaction between components, and will explain how composition and
encapsulation can control enzymatic activities in native condensates. Finally, we will learn how
internucleosome spacing and diverse histone post-translational modifications control chromatin LLPS to
generate biochemically and functionally distinct genomic regions, examine whether NUT carcinoma is caused
by defective LLPS, and develop a new approach to drug design based on targeting small molecules to
condensates. Together, the work will reveal new principles of biological phase separation, explain how phase
separation can be used to control RNA metabolism and geno...

## Key facts

- **NIH application ID:** 10494077
- **Project number:** 5R35GM141736-02
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** Michael K Rosen
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $369,000
- **Award type:** 5
- **Project period:** 2021-09-25 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10494077

## Citation

> US National Institutes of Health, RePORTER application 10494077, Cell Organization Through Phase Separation:  Mechanisms, Functions and Disease (5R35GM141736-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10494077. Licensed CC0.

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