The arginine methyltransferase CARM1 represses p300•ACT•CREMτ activity and is required for spermiogenesis

Area of Science:

• Reproductive biology
• Epigenetics
• Molecular mechanisms of gene regulation

Background:

• CARM1 (protein arginine methyltransferase 1) is involved in transcriptional regulation.
• Its precise role in tissue-specific contexts, like male germ cell development, remains unclear.

Purpose of the Study:

• To investigate the function of CARM1 in mouse spermiogenesis.
• To elucidate the molecular mechanisms underlying CARM1's role in male germ cell development.

Main Methods:

• Generation of a germline-specific conditional Carm1 knockout mouse model.
• Analysis of sperm count and morphology.
• RNA-sequencing (RNA-seq) of Carm1-null spermatids.
• Investigation of protein-protein interactions involving CARM1, p300, and CREMτ.

Main Results:

• CARM1 is highly expressed in mouse spermatids and essential for late-stage haploid germ cell development.
• Carm1 deficiency results in low sperm count and deformed sperm heads due to defective spermatid elongation.
• RNA-seq data links CARM1-regulated genes to those affected by p300 loss, suggesting a functional connection.
• CARM1 methylates p300, negatively regulating the interaction between p300, its activator ACT, and the transcription factor CREMτ.

Conclusions:

• CARM1 plays a critical role in spermiogenesis, specifically in the late stages of haploid germ cell development.
• The findings reveal a novel mechanism where CARM1 regulates male fertility by modulating the p300•ACT•CREMτ axis through p300 methylation.