# CARF regulates the alternative splicing and piwi/piRNA complexes during mouse spermatogenesis through PABPC1: CARF regulates spermatogenesis through PABPC1

## TL;DR

This study shows that CARF regulates spermatogenesis in mice by influencing RNA splicing and piRNA complexes through PABPC1.

## Contribution

The novel finding is that CARF regulates spermatogenesis via PABPC1, impacting RNA splicing and piRNA pathways.

## Key findings

- Male mice lacking CARF exhibit impaired spermatogenesis and fertility.
- CARF interacts with splicing factors like PABPC1 and regulates 356 mRNAs in spermatocytes.
- CARF deficiency alters PIWIL1 expression and pachytene-piRNA ratios through PABPC1 downregulation.

## Abstract

ADP-ribosylation factor collaborator (CARF), which is also known as CDKN2AIP, was first recognized as an ADP-ribosylation factor-interacting protein that participates in the activation of the ARF-p53-p21 (WAF1) signaling pathway under different conditions, such as oxidative and oncogenic stresses. The activation of this pathway often leads to cell growth arrest and apoptosis as well as senescence. Previous studies revealed that CARF, an RNA-binding protein, is critical for maintaining stem cell pluripotency and somatic differentiation. Nevertheless, its involvement in spermatogenesis has not been well examined. In this study, we show that male mice deficient in
Carf expression present impaired spermatogenesis and fertility. IP-MS and RNA-seq analyses reveal that CARF/
Carf interacts with multiple key splicing factors, such as PABPC1, and directly targets 356 different types of mRNAs in spermatocytes.
Carf-associated mRNAs display aberrant splicing patterns when Carf expression is deficient. In addition, our results demonstrate that PIWIL1 expression and localization are altered in the
Carf

-/
-
mouse model through the downregulation of PABPC1, which further affects the ratio of pachytene-piRNA. Our study suggests that CARF is critical for regulating alternative splicing in mammalian spermatogenesis and determining infertility in male mice.