# Kyushu University: histone H3mm15 supports sperm development in mice, differing from H3.3 by 3 amino acids

- Published: 2026-11-09 04:09 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: histone H3.3 subvariant, H3mm15, spermatogenesis in mice, nucleosome stability, seminiferous tubules, chromatin dynamics, histone sub-barcode, Nucleic Acids Research
- URL: https://realtech.media/news/rt-c93701ea9df18303708fafeb_kyushu_university_histone/

**In mice lacking H3mm15, a histone H3.3 subvariant, seminiferous tubules were disorganized and sperm motility was reduced. The work was published in Nucleic Acids Research.**

![Kyushu University: histone H3mm15 supports sperm development in mice, differing from H3.3 by 3 amino acids](https://realtech.media/media/2026/11/3b02c7e048b3743e.jpg)
*Sinkevichvictoria, Wikimedia Commons, CC BY 4.0*

Researchers at Kyushu University, Japan, report that H3mm15, a subvariant of histone H3.3, contributes to normal sperm development in mice by helping regulate gene expression during spermatogenesis, according to kyushu-u.ac.jp [1]. The study was led by Professor Akihito Harada of the Faculty of Medical Sciences and published online in Nucleic Acids Research on November 9, 2026. The team worked with Qianmei Wu, Distinguished Professor Yasuyuki Ohkawa of the Medical Institute of Bioregulation, and Professor Tatsuya Takemoto of Tokushima University. [1]

H3mm15 differs from conventional H3.3 at only three amino acids. RNA analyses showed that the gene encoding it is predominantly expressed in the testis. The authors found that the two proteins are not interchangeable: they behave differently in chromatin, the DNA-protein structure that packages genetic material. [1]

## Effects of H3mm15 loss in mice

The researchers generated H3mm15-deficient mice and assessed testis structure, sperm motility and gene expression. The animals showed disorganized seminiferous tubules, the structures in which sperm develop, and reduced sperm motility. Expression of spermatogenesis-related genes was altered, particularly those associated with the transition into meiosis. [1]

## Chromatin behavior of the subvariant

In cultured cells, H3mm15 was incorporated into chromatin less efficiently than H3.3 but was relatively enriched near promoters, where transcription begins. Analysis of transgenic mouse testes also detected H3mm15-EGFP enrichment around transcription start sites. [1]

Structural and biochemical analyses showed that H3mm15 forms less stable nucleosomes, the basic units of chromatin, than H3.3. Live-cell measurements showed more dynamic association with chromatin, with glutamine at position 100 contributing strongly to this behavior. Under the conditions tested, nucleosomes containing H3mm15 did not enhance RNA polymerase II transcription in vitro, so reduced nucleosome stability alone does not explain the effect on gene regulation. [1]

The authors propose a "histone sub-barcode" model, in which closely related H3.3 subvariants confer distinct chromatin properties through differences in genomic localization, stability and dynamics. Harada noted that H3mm15 is a mouse subvariant and that additional studies are required before considering applications to humans. [1]

## Sources

1. [kyushu-u.ac.jp](https://www.kyushu-u.ac.jp/en/)
2. [news-medical.net](https://www.news-medical.net/news/20261108/Histone-subvariant-H3mm15-plays-key-role-in-sperm-development.aspx)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-c93701ea9df18303708fafeb_kyushu_university_histone/