# Mechanisms of Genomic Stability by Mammalian Argonaute Proteins

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2024 · $327,600

## Abstract

Project Summary/Abstract
Genome instability increases the rates of mutations, chromosomal rearrangements, and aneuploidy and drives
many age-related human diseases, including cancer. The challenges of replicating our genome and
epigenome with each cell division requires molecular pathways that ensure the propagation of stable genomes
to daughter cells. To date, the roles of mammalian noncoding RNAs (ncRNAs) in the maintenance of genome
stability is incompletely understood. We propose that filling this gap is essential to expand our knowledge of
human development and homeostasis and to identify novel risk factors that contribute to human disease. In
fission yeast, the RNA interference (RNAi) pathway acts during DNA synthesis at the repeats of
pericentromeres via locally produced ncRNAs to establish the heterochromatin needed for genome stability. It
is unclear if similar cell cycle-specific RNAi mechanisms of genome stability are present in mammals. In
preliminary studies, we used mouse stem cell systems to map high-confidence interactions of the RNAi
effector Argonaute (Ago) proteins with ncRNAs. We determined that Ago binds directly to pericentromeric
ncRNAs. Furthermore, we found that pericentromeric ncRNAs are overexpressed during DNA synthesis in
Ago-deficient cells and observed multiple signatures of genomic instability caused by full Ago depletion. In
parallel, previous studies in mouse models have established that overexpression of pericentromeric ncRNA
suffices to cause genomic instability and tumorigenesis. Based on these intriguing findings, we hypothesize
that pericentromeric ncRNA expression, established via cell cycle-specific Ago regulation, is critical for the
maintenance of genomic stability in mammalian cells, analogous to fission yeast. In this RO1 research project,
we examine the potential roles of RNAi in preventing genomic instability caused by accumulating
pericentromeric ncRNA and/or disruption of local heterochromatin structure. We propose to define cell cycle-
specific Ago activities to elucidate the molecular triggers for pericentromere regulation and to determine how
pericentromeric ncRNAs contribute to genome stability. In Aim 1, we will determine how and when Ago
functions at pericentromeres for the establishment of heterochromatin. In Aim 2, we determine the direct
molecular consequence of Ago recruitment to chromatin. Finally, in Aim 3, we will elucidate how ncRNAs
control Ago activity at pericentromeres during cell cycle progression. These innovative studies will answer the
long-standing question of whether the mammalian RNAi pathway contributes to the maintenance of
pericentromere heterochromatin and genome stability and will break new ground in our understanding of RNA-
mediated gene regulation. We predict these studies will drive and yield a framework for future strategies to
modulate pericentromeric ncRNA in disease settings.

## Key facts

- **NIH application ID:** 10874652
- **Project number:** 5R01GM143536-04
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Jesse R. Zamudio
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $327,600
- **Award type:** 5
- **Project period:** 2021-09-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10874652

## Citation

> US National Institutes of Health, RePORTER application 10874652, Mechanisms of Genomic Stability by Mammalian Argonaute Proteins (5R01GM143536-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10874652. Licensed CC0.

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