Nucleosomes in mammalian sperm: conveying paternal epigenetic inheritance or subject to reprogramming between generations?

The genome of mammalian sperm is largely packaged by sperm-specific proteins termed protamines. The presence of some residual nucleosomes has, however, emerged as a potential source of paternal epigenetic inheritance between generations. Sperm nucleosomes bear important regulatory histone marks and locate at gene-regulatory regions, functional elements, and intergenic regions. It is unclear whether sperm nucleosomes are retained at specific genomic locations in a deterministic manner or are randomly preserved due to inefficient exchange of histones by protamines. Recent studies indicate heterogeneity in chromatin packaging within sperm populations and an extensive reprogramming of paternal histone marks post fertilization. Obtaining single-sperm nucleosome distributions is fundamental to estimating the potential of sperm-borne nucleosomes in instructing mammalian embryonic development and in the transmission of acquired phenotypes.

Automated summary

The genome of mammalian sperm is packaged by protamines, but some residual nucleosomes may contribute to paternal inheritance. Sperm nucleosomes carry important histone marks and can be found in gene-regulatory regions and intergenic regions. It is unclear whether sperm nucleosomes are retained in a deterministic or random manner. Recent studies suggest heterogeneity in chromatin packaging within sperm populations and extensive reprogramming of paternal histone marks post fertilization. Understanding the distribution of single-sperm nucleosomes is essential for assessing their role in mammalian embryonic development and the transmission of acquired phenotypes.