Programmable human histone phosphorylation and gene activation using a CRISPR/Cas9-based chromatin kinase

Area of Science:

• Epigenetics and Molecular Biology
• Gene Regulation
• CRISPR Technology

Background:

• Histone phosphorylation is crucial for cellular responses but its causal role in gene expression is hard to establish.
• Existing technologies lack locus-specific control over endogenous histone phosphorylation.

Purpose of the Study:

• To develop a novel epigenome editing tool for targeted histone phosphorylation.
• To investigate the causal role of histone H3 serine 28 phosphorylation (H3S28ph) in gene activation.
• To identify drug resistance mechanisms in melanoma cells.

Main Methods:

• Construction of a programmable chromatin kinase (dCas9-dMSK1) by fusing nuclease-null CRISPR/Cas9 with a hyperactive MSK1 variant.
• Targeting dCas9-dMSK1 to human promoters to induce histone phosphorylation and gene activation.
• Genome-scale screening in human melanoma cells to identify resistance mediators to BRAF V600E inhibitor PLX-4720.

Main Results:

• dCas9-dMSK1 successfully induced target histone phosphorylation and gene activation at specific loci.
• Hyperphosphorylation of H3S28ph was shown to causally promote human promoter transactivation.
• The tool facilitated the discovery of mediators of resistance to PLX-4720 in melanoma.

Conclusions:

• dCas9-dMSK1 provides a facile method for epigenome editing and reshaping chromatin.
• This technology strengthens the understanding of the causal relationship between histone phosphorylation and gene activation.
• The findings offer new insights into drug resistance mechanisms in cancer therapy.