Pdtm-39. Histone H3 Mutation Effects on Chromatin Structure and Regulation of Gene Transcription in Pediatric Glioma
Year: 2018
Type: conference-abstract
Abstract: Pediatric high-grade glioma (HGG), including H3K27M diffuse midline glioma, has the highest mortality of pediatric solid tumors. Recurrent Histone H3 mutations result in methionine for lysine substitution (H3K27M) in 80% of diffuse midline gliomas, or valine for glycine/arginine substitution (G34V/R) in 50% of hemispheric HGGs. These mutations alter chromatin structure and are associated with distinct patterns of gene expression and poorer response to therapy. To elucidate the mechanism by which these mutations affect chromatin function, we characterized genomic deposition of Histone H3 proteoforms in a large cohort of rare pediatric glioma cell lines. H3K27M DIPG (n=6), H3G34V (n=1) and wild-type pediatric high-grade glioma cells (n=2), neural stem cells (n=1) and astrocytes (n=1) were analyzed for genomic deposition patterns of H3.3, H3K27M, H3G34V, H3K27me3, H3K27Ac, H4Kme1, and H4Kme3. Extracted chromatins were sonicated to produce DNA fragments for ChIP. RNA was extracted for whole transcriptome profiling. DNA/RNA libraries were prepared using the KAPA HTP Library Preparation Kit and sequenced (ChIP-and RNA-Seq, Illumina NextSeq 500). Genomic enrichments and gene expressions were determined, quantified, and analyzed for biological relevance. Distinct genomic enrichment of H3 proteoforms was observed between mutant and wild type cell lines, corresponding with respective gene expression levels. Differential co-localization of H3 post-translational marks with mutant vs. wild type H3 protein was also observed, consistent with our prior description of mutant heterotypic nucleosomes. Location of specific marks (promoter, gene body) suggests altered transcription factor recruitment and function may result in observed patterns of gene expression. We present the largest known epigenetic analysis of pediatric glioma cell lines to date, indicating distinct patterns of Histone H3 enrichment and gene expression in H3K27M and H3G34V/R mutant lines. These data provide insight into the mechanisms by which H3 mutations impact pediatric glioma biology, which may inform novel therapeutic approaches.
Source: Neuro-Oncology
Institution: Northwestern University
Language: English
Subfield: Genetics
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2900311443