Transcriptome analysis of WT versus H2A.J-KO MEFs for the paper entitled: The H2A.J histone variant contributes to Interferon-Stimulated Gene expression in senescence by its weak interaction with H1 and the derepression of repeated DNA sequences

Abstract for overall study:

The histone variant H2A.J was previously shown to accumulate in senescent human fibroblasts with persistent DNA damage to promote inflammatory gene expression, but its mechanism of action was unknown. We show that H2A.J accumulation contributes to weakening the association of histone H1 to chromatin and increasing its turnover. Decreased H1 in senescence is correlated with increased expression of some repeated DNA sequences, increased expression of STAT/IRF transcription factors, and transcriptional activation of Interferon-Stimulated Genes (ISGs). The H2A.J-specific Val-11 moderates the transcriptional activity of H2A.J, and H2A.J-specific Ser-123 can be phosphorylated in response to DNA damage with potentiation of its transcriptional activity by the phospho-mimetic S123E mutation. Our work demonstrates the functional importance of H2A.J-specific residues and potential mechanisms for its function in promoting inflammatory gene expression in senescence.

Specific description for this dataset:

We further tested a role for H2A.J in Interferon-Stimulated Gene expression by analyzing the transcriptome of WT and H2A.J MEFs induced into senescence by etoposide. TruSeq stranded DNA libraries were prepared from polyA-selected RNA and sequenced as 43 bp paired-end reads. The fastq sequences were mapped to Gencode.vM24.transcripts.fa.gz (GRCm38 transcriptome) with salmon. Read counts were then aggregated to the gene level with tximeta, and differential gene expression was analysed with DESeq2, edgeR, and limma-voom. Gene set enrichment analysis was performed with camera.

The transciptomes of  senescent WT and H2AFJ-KO showed strong separation from proliferating MEFs, and a weaker separation distinguished WT and H2A.J-KO MEFs. Strikingly, gene set enrichment analysis indicated highly significant defects in Interferon Response Gene Expression in the H2A.J-KO MEFs in senescence with significant down-regulation in senescent H2A.J-KO cells of a series of oligoadenylate synthase genes (Oas1g, Oas1a, Oasl1, Oas2, Oasl2) and several ISGs. Thus, H2A.J also contributes to ISG expression in the heterologous context of senescent MEFs.