# ARS2, a Cofactor of CBC, Promotes Meiotic Silencing by Unpaired DNA

## TL;DR

ARS2, a protein that works with CBC, helps silence unpaired DNA during meiosis in Neurospora crassa and supports other cellular processes.

## Contribution

ARS2 is identified as a new cofactor involved in meiotic silencing by unpaired DNA (MSUD) through interactions with CBC and NCBP3.

## Key findings

- ARS2 interacts with CBC and NCBP3 to mediate meiotic silencing by unpaired DNA.
- ARS2 is essential for vegetative growth and sexual sporulation in Neurospora crassa.
- ARS2 may facilitate the assembly of the MSUD complex by bridging CBC and NCBP3.

## Abstract

The presence of an extra DNA segment in a genome could indicate a transposon or another repetitive element on the move. In Neurospora crassa, a surveillance mechanism called meiotic silencing by unpaired DNA (MSUD) is maintained to monitor these selfish elements. MSUD utilizes common RNA interference (RNAi) factors, including the SMS-2 Argonaute, to target mRNAs from genes lacking a pairing partner during meiosis. In eukaryotes, an mRNA transcript is typically bound at the 5′ cap by the cap-binding complex (CBC), which assists in its nuclear export. Previously, we discovered that CBC and its interactor NCBP3 mediate MSUD, possibly by guiding the perinuclear SMS-2 to effectively recognize exported mRNAs. Here, we report that ARS2, a CBC cofactor, is involved in MSUD. ARS2 interacts with both CBC and NCBP3, and it may help bring them together. In addition to its role in silencing, ARS2 also contributes to vegetative growth and sexual sporulation.