# Regulation of piRNA pathway by the Nuclear Pore Complex

> **NIH NIH R01** · MEDICAL UNIVERSITY OF SOUTH CAROLINA · 2021 · $313,950

## Abstract

Project Summary/Abstract
 Transposable elements (TEs), also known as jumping genes are mobile DNA elements that move from
one genomic location to the other in the genome. The activity of TEs can cause major changes in genome
structure and must be restricted to prevent developmental defects, aging, neurodegenerative diseases and
cancer. TE mobility is silenced during germline development to prevent genome changes from being passed
on to the progeny. In the germline, piRNA pathway silences transposons. The primary function of the piRNA
pathway is mediated by PIWI clade proteins which in Drosophila are represented by Piwi, Aubergine (Aub) and
Argonaute 3 (Ago3) proteins. These proteins bind piRNAs (~26 nucleotides in length) and target TEs through
sequence-specific complementarity. All three proteins have non-redundant function in silencing TE. TE
silencing in the germline is compartmentalized. Piwi is nuclear and is needed for transcriptional silencing of
TEs. Aub and Ago3 are cytoplasmic and are needed for post-transcriptional silencing of TEs. Majority of
piRNAs are made by Aub and Ago3 involved ping-pong amplification that occurs in the nuage, a RNA-rich
perinuclear granule. In the germline cells, Aub and Ago3 participate in ping-pong cycle to produce piRNAs and
these piRNAs are loaded onto Piwi; however, neither the mechanism nor the proteins involved in coupling
piRNA biogenesis with piRNA loading onto Piwi are known. Aub and Ago3 need to interact for piRNA
biogenesis; however the mechanism by which Aub and Ago3 interact is not known. A seamless network needs
to exist between the nuclear pore complex (NPC) and the nuage to ensure that Piwi-piRNA complexes
assembled in the nuage translocate into the nucleus and silence transposons; however the mechanism by
which the NPC might regulate Piwi nuclear function is elusive. Our preliminary data shows for the first time that
Nup358, a key component of cytoplasmic filaments of the NPC, interacts with Piwi and is required for a) Piwi's
entry into the nucleus, b) TE silencing, c) loading of piRNAs onto Piwi, d) piRNA biogenesis, and e) Aub-Ago3
interaction. These data suggest that Nup358 is a key player in piRNA pathway and by characterizing how
Nup358 regulates piRNA pathway, we will reveal significant insights into how the NPC promotes piRNA
biogenesis, TE silencing and genome stability. The scientific premise of this proposal is that there is sufficient
evidence that Nup358 is a key player in piRNA pathway, but the mechanism by which Nup358 achieves the
same is elusive. Based on the preliminary data, we hypothesize that Nup358 recruits Piwi to the nuclear
membrane and couples piRNA biogenesis with piRNA loading onto Piwi. To test this hypothesis, we will
biochemically define Piwi-Nup358 interaction (Aim I) and unravel the mechanism by which Nup358 couples
piRNA biogenesis with piRNA loading onto Piwi (Aim II).

## Key facts

- **NIH application ID:** 10153819
- **Project number:** 5R01GM130846-03
- **Recipient organization:** MEDICAL UNIVERSITY OF SOUTH CAROLINA
- **Principal Investigator:** VAMSI GANGARAJU
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $313,950
- **Award type:** 5
- **Project period:** 2019-08-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10153819

## Citation

> US National Institutes of Health, RePORTER application 10153819, Regulation of piRNA pathway by the Nuclear Pore Complex (5R01GM130846-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10153819. Licensed CC0.

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