Dataset Information

Epigenetic landscape of testis specific histone H2B variant and its influence on sperm function.

ABSTRACT:

Background

Biological relevance of the major testis specific histone H2B variant (TH2B) in sperm is not fully understood. Studies in TH2A/TH2B double knockout male mice indicate its role in chromatin compaction and male fertility. Additionally, the presence of TH2B and TH2A reportedly generates more dynamic nucleosomes, leading to an open chromatin structure characteristic of transcriptionally active genome. Given that mature human sperm are transcriptionally and translationally inactive, the presence of TH2B in mature sperm is intriguing. To address its role in sperm, we investigated the genome-wide localization of TH2B in sperm of fertile men.

Results

We have identified the genomic loci associated with TH2B in fertile human sperm by ChIP-seq analysis. Bioinformatic analysis revealed ~ 5% sperm genome and 5527 genes to be associated with TH2B. Out of these 105 (1.9%) and 144 (2.6%) genes showed direct involvement in sperm function and early embryogenesis, respectively. Chromosome wide analysis for TH2B distribution indicated its least distribution on X and Y chromosomes and varied distribution on autosomes. TH2B showed relatively higher percentage of gene association on chromosome 4, 18, 3 and 2. TH2B enrichment was more in promoter and gene body region. Gene Ontology (GO) analysis revealed signal transduction and associated kinase activity as the most enriched biological and molecular function, respectively. We also observed the enrichment of TH2B at developmentally important loci, such as HOXA and HOXD and on genes required for normal sperm function, few of which were validated by ChIP-qPCR. The relative expression of these genes was altered in particular subgroup of infertile men showing abnormal chromatin packaging. Chromatin compaction positively correlated with sperm- motility, concentration, viability and with transcript levels of PRKAG2 and CATSPER B.

Conclusion

ChIP-seq analysis of TH2B revealed a putative role of TH2B in sperm function and embryo development. Altered expression of TH2B associated genes in infertile individuals with sperm chromatin compaction defects indicates involvement of TH2B in transcriptional regulation of these genes in post meiotic male germ cells. This altered transcriptome may be a consequence or cause of abnormal nuclear remodeling during spermiogenesis.

SUBMITTER: Patankar A

PROVIDER: S-EPMC8088685 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Bull fertility is the degree of sperm's ability to fertilize and activate the egg and support embryo development, and this is critical for herd reproductive performance. We used the bull as a unique model organism for the study of male fertility because cattle genetics and physiology is similar to those of other mammals including humans. Moreover, reliable fertility data along with well-established in vitro systems are available for bovine. The objective of this original study was to ascertain evolutionary diversification and expression dynamics of Testis Specific Histone 2B (TH2B) in sperm from Holstein bulls with different fertility scores.The intensity of TH2B was determined by using flow cytometry in sperm from 13 high and 13 low fertility bulls. Expression levels of TH2B were measured using immunofluorescence and Western blotting in sperm from five high and five low fertility bulls. Sequence identity, evolutionary distance and interactome of TH2B were evaluated by dotmatcher, STRING and Cytoscape. Data were analyzed using linear mixed effects model and regression plots were drawn.The intensity of TH2B as measured by flow cytometry was significantly affected by an interaction between fertility group and fertility score (P = 0.0182). The intensity of TH2B in sperm from the high fertility group decreased (P = 0.0055) as fertility increased. TH2B was constantly detectable in sperm and expression levels of TH2B decreased in relation to fertility in sperm from the high fertility group (P = 0.018). TH2B biological functions include male gamete generation, chromosome organization, DNA packaging, DNA conformation change, chromatin organization, nucleosome organization, chromatin disassembly, spermatid nucleus elongation, spermatid nucleus differentiation, sperm motility, chromatin organization, chromatin condensation, chromatin silencing, nucleus organization, and chromatin remodeling (P < 0.05).We elucidated the cellular localization and molecular physiology of TH2B using both computational and cell biology approaches. In addition to advancing the fundamental science of mammalian male gamete, the present findings can be potentially used to evaluate semen quality and predict male fertility in the future.This study did not involve any live animals. We did not perform any anesthesia, euthanasia, or any kind of animal sacrifice. The cryopreserved semen samples were obtained from Alta Genetics, Inc., Watertown, WI, USA. All samples were preserved in liquid nitrogen.