Nucleotide variation in histone H2BL drives crossalk of histone modification and promotes tumour cell proliferation by upregulating c-Myc

Levels of post-translationally modified histones in ground squirrel livers are altered during deep torpor

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are obligate hibernators capable of reducing their metabolic rates by up to 99 % during winter. Their ability to remain dormant without food for an extended period in cold conditions has made them compelling subjects for research. Developing a clearer understanding of mechanisms surrounding the pre-transcriptional control of hibernating tissues is crucial for cryobiological applications such as organ preservation. Thus, we investigated the differential expression of 24 modified histones (MH) in the livers of torpid and euthermic free-ranging ground squirrels by immunoblotting histone-enriched extracts (p < 0.05). We identified the torpor-responsive downregulation of multiple permissive MHs (H2BK5ac, H3K18ac, H3K23ac, H3K27ac, H3K4me2, H3K4me3, H4K20me1, H4R3me2s), including total H2B and H4, while the linker histone H1.0 was the only histone species that was upregulated. The present study provides valuable insights into the involvement of histone post-translational modifications in the epigenetic landscape of deeply torpid ground squirrel livers.

Beyond the Usual Suspects: Examining the Role of Understudied Histone Variants in Breast Cancer

The incorporation of histone variants has structural ramifications on nucleosome dynamics and stability. Due to their unique sequences, histone variants can alter histone-histone or histone-DNA interactions, impacting the folding of DNA around the histone octamer and the overall higher-order structure of chromatin fibers. These structural modifications alter chromatin compaction and accessibility of DNA by transcription factors and other regulatory proteins to influence gene regulatory processes such as DNA damage and repair, as well as transcriptional activation or repression. Histone variants can also generate a unique interactome composed of histone chaperones and chromatin remodeling complexes. Any of these perturbations can contribute to cellular plasticity and the progression of human diseases. Here, we focus on a frequently overlooked group of histone variants lying within the four human histone gene clusters and their contribution to breast cancer.