# Uncovering the Molecular Principles for Microphase Separation by Nuclear Speckle Proteins and RNA Transcripts

> **NIH NIH K99** · WASHINGTON UNIVERSITY · 2024 · $125,000

## Abstract

Project Summary Abstract
Nuclear speckles are an archetypal biomolecular condensates that are essential to either
activating or repressing target gene expression. Unsuccessful control of gene expression
is associated with development and progression of human cancers. Understanding the
mechanism underlying nuclear speckle formation and functions can uncover possible
modes of action for therapeutics.
The main scaffold of nuclear speckles is formed by RNA and RNA binding proteins
(RBPs), which have modular architectures of multiple domains, termed RNA recognition
motifs (RRMs) and intrinsically disordered regions (IDRs). I propose to develop a
comprehensive approach to study the specific arrangement of RRMs and IDRs in RBP
assemblies and how each of RRM or IDR affects nuclear speckle formation and functions.
Typically, RRMs can be readily identified by protein sequence that is evolutionarily
maintained and their functions can be predicted. However, function cannot be easily
predicted for IDRs from their sequences due to a large variability throughout evolution.
Using modern computational analyses, I have identified the distinct molecular architecture
and sequence features of the IDRs in nuclear speckle proteins that are obscured by
variability in sequence. These indicate that the proteins should undergo a specific
arrangement into assemblies with limited size. I will test these predictions by experiments
using isolated proteins and RNA, and in live cells. I will use model nuclear speckle
proteins, the SRSFs. In Aim 1, I will experimentally test how variations in the molecular
architecture contribute to nuclear speckle formation by studying SRSF family proteins that
naturally vary in the number of RRMs and IDR sequence features. Aims 2 and 3 will be
studied during the independent phase of this grant (R00). In Aim 2, I will investigate how
the individual assemblies of SRSF proteins are held together by a core of speckles. In
Aim 3, I will investigate how different nuclear speckle proteins are released and move
outside of nucleus under cellular stress.
This award will support training in computational simulations and advanced experiments.
Together these aims will support the long-term goal of uncovering the molecular
mechanism underlying assembly and functions of nuclear speckles from the distinct
features in the protein sequence.

## Key facts

- **NIH application ID:** 10984809
- **Project number:** 1K99GM152778-01A1
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Min Kyung Shinn
- **Activity code:** K99 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $125,000
- **Award type:** 1
- **Project period:** 2024-08-01 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10984809

## Citation

> US National Institutes of Health, RePORTER application 10984809, Uncovering the Molecular Principles for Microphase Separation by Nuclear Speckle Proteins and RNA Transcripts (1K99GM152778-01A1). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10984809. Licensed CC0.

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