Histone methyltransferase MET-2 regulates autosome and X-chromosome structure differently during C. elegans meiosis

Researchers have posted a preprint to bioRxiv reporting that MET-2, a histone methyltransferase that catalyses dimethylation of histone H3 at lysine 9 (H3K9me2), plays distinct and sex-specific roles in shaping chromosome structure and transcription during meiosis in the nematode Caenorhabditis elegans.

Accurate chromosome segregation during meiosis depends on substantial chromosome condensation and compaction, processes mediated by condensin and cohesin complexes alongside histone tail modifications. Using met-2 null worms, the team found that autosomes during spermatogenesis are significantly larger than in wild-type animals, implying impaired compaction; however, chromosome size during oogenesis is unaffected. X univalent size in males is similarly unaffected by MET-2 loss. The preprint further characterises differential effects on transcription across the two germline contexts.

The findings add to evidence that H3K9 methylation contributes to meiotic chromosome organisation in a context-dependent manner, and raise questions about how the same chromatin-modifying enzyme can exert such divergent effects depending on the sex of the germline and the chromosome type involved. C. elegans is an established model organism for studying germline biology, chromosome segregation, and the interplay between epigenetic modifications and genome stability.

This work is a preprint and has not yet been peer-reviewed.