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Published on: January 26, 2018
Histone H3 lysine-to-methionine mutants as a paradigm to study chromatin signaling
Hans-Martin Herz1, Marc Morgan1, Xin Gao1
1Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA.
Abstract:
Histone H3 lysine(27)-to-methionine (H3K27M) gain-of-function mutations occur in highly aggressive pediatric gliomas. We established a Drosophila animal model for the pathogenic histone H3K27M mutation and show that its overexpression resembles polycomb repressive complex 2 (PRC2) loss-of-function phenotypes, causing derepression of PRC2 target genes and developmental perturbations. Similarly, an H3K9M mutant depletes H3K9 methylation levels and suppresses position-effect variegation in various Drosophila tissues. The histone H3K9 demethylase KDM3B/JHDM2 associates with H3K9M-containing nucleosomes, and its misregulation in Drosophila results in changes of H3K9 methylation levels and heterochromatic silencing defects. We have established histone lysine-to-methionine mutants as robust in vivo tools for inhibiting methylation pathways that also function as biochemical reagents for capturing site-specific histone-modifying enzymes, thus providing molecular insight into chromatin signaling pathways.
Insights
Histone H3 lysine(27)-to-methionine (H3K27M) mutations in pediatric gliomas were modeled in Drosophila. These mutants disrupt methylation pathways, offering new tools for studying chromatin signaling and enzyme interactions.
Area of Science:
- Molecular Biology
- Genetics
- Epigenetics
Background:
- Gain-of-function H3K27M mutations are linked to aggressive pediatric gliomas.
- Histone methylation is crucial for gene regulation and chromatin structure.
Purpose of the Study:
- To establish Drosophila models for pathogenic histone H3K27M and H3K9M mutations.
- To investigate the in vivo effects of these histone mutants on methylation pathways and gene expression.
- To explore the utility of histone lysine-to-methionine mutants as tools for studying chromatin signaling.
Main Methods:
- Generation of Drosophila melanogaster models expressing H3K27M and H3K9M mutants.
- Analysis of Polycomb Repressive Complex 2 (PRC2) target gene expression.
- Assessment of H3K9 methylation levels and position-effect variegation.
- Biochemical assays to study the interaction of KDM3B/JHDM2 with H3K9M nucleosomes.
Main Results:
- H3K27M overexpression phenocopied PRC2 loss-of-function, leading to gene derepression and developmental issues.
- H3K9M mutants reduced H3K9 methylation and affected heterochromatic silencing.
- KDM3B/JHDM2 was found to associate with H3K9M nucleosomes, and its misregulation impacted H3K9 methylation.
Conclusions:
- Histone lysine-to-methionine mutants serve as effective in vivo tools for inhibiting methylation pathways.
- These mutants provide insights into chromatin signaling by acting as biochemical reagents for enzyme capture.
- The study validates Drosophila as a model for investigating histone mutations in cancer and chromatin biology.
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