# Coordination of phase separation and translational control by the RNA helicase DDX3X

> **NIH NIH F30** · CASE WESTERN RESERVE UNIVERSITY · 2021 · $51,036

## Abstract

Project Abstract
DDX3X is an essential translation initiation factor that is conserved from yeast to human. Deregulated DDX3X
expression, DDX3X mutations, or both, are linked to several cancers, including breast, colorectal, lung, oral
squamous cell cancers, and medulloblastoma, a pediatric brain cancer. In medulloblastoma, DDX3X mutations
promote formation of cytoplasmic messenger ribonucleoprotein (mRNP) granules (stress granules), which form
by liquid-liquid phase separation and are associated with global changes in translation. Several lines of evidence
suggest that stress granule formation and global changes in translation occur in other cancers as well, and that
DDX3X plays a key role in linking these processes. How DDX3X coordinates translation initiation and granule
formation is not understood. This proposal directly addresses this problem. Aim 1 combines enzymological
techniques with fluorescence microscopy to define the relationship between DDX3X phase separation and
helicase activity. Preliminary data show that direct interaction with the vaccinia virus protein K7, which binds the
N-terminal intrinsically disordered region of DDX3X, disrupts DDX3X granules and suppresses DDX3X
enzymatic activity. The effect of RNA, ATP, and K7 binding on DDX3X granule dynamics will be characterized
to develop a model for the impact of phase separation on DDX3X helicase activity and to test the ability of K7 to
disrupt cancer-associated DDX3X granules. Aim 2 uses ribosome profiling to characterize the interplay between
DDX3X phase separation and translational control. Translational signatures resulting from DDX3X depletion,
DDX3X granule formation, and the disruption of DDX3X granules by K7 will be compared to identify how DDX3X
phase separation alters translation and whether these changes can be reversed by granule disruption. Expected
data will chart new territory for understanding biochemical and enzymatic aspects of mRNP granule formation.
The work will also provide a roadmap for the mechanistic analysis of other RNA binding proteins that associate
with cytoplasmic granules. Finally, since inhibition of DDX3X catalytic activity promotes granule formation that
may drive tumorigenesis, as is suggested for medulloblastoma, the simultaneous disruption of granules and
suppression of DDX3X activity by K7 or similar effectors may represent a new strategy for the treatment of
cancers linked to DDX3X malfunction.

## Key facts

- **NIH application ID:** 10241287
- **Project number:** 5F30CA247347-02
- **Recipient organization:** CASE WESTERN RESERVE UNIVERSITY
- **Principal Investigator:** Sarah Linn Venus
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $51,036
- **Award type:** 5
- **Project period:** 2020-08-15 → 2024-08-14

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10241287

## Citation

> US National Institutes of Health, RePORTER application 10241287, Coordination of phase separation and translational control by the RNA helicase DDX3X (5F30CA247347-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10241287. Licensed CC0.

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