Set1-dependent H3K4 methylation is essential for sustained gene expression at newly activated loci

Area of Science:

• Molecular Biology
• Epigenetics
• Yeast Genetics

Background:

• Histone H3 lysine 4 trimethylation (H3K4me3) is linked to active gene transcription.
• The precise role of H3K4me3 as a driver of gene activation is not fully understood.

Purpose of the Study:

• To investigate the causative role of H3K4me3 in gene activation.
• To determine the function of the Paf1 complex subunit Leo1 in gene regulation.

Main Methods:

• Deletion of the Leo1 gene in Saccharomyces cerevisiae.
• Analysis of gene expression and H3K4me3 levels using ChIP-seq.
• Investigating the dependency on the H3K4 methyltransferase Set1.

Main Results:

• Leo1 deletion induced specific gene activation, particularly for sterol transport genes, without changing global H3K4me3.
• Induced genes gained de novo H3K4me3 dependent on Set1.
• Loss of Set1 abolished gene expression, even with existing H3K4me3, and reintroduction restored it.

Conclusions:

• Set1-catalyzed H3K4me3 acts as a context-dependent driver of gene expression.
• Leo1 deficiency specifically impacts gene activation through Set1-mediated H3K4me3.
• This mechanism has physiological relevance, enhancing sterol uptake.