Histone H3 lysine 9 (H3K9) methylation is a hallmark of heterochromatin. H3K9 demethylation is crucial in mouse sex determination; The H3K9 demethylase Jmjd1a deficiency leads to increased H3K9 methylation at the Sry locus in embryonic gonads, thereby compromising Sry expression and causing male-to-female sex reversal. We hypothesized that the H3K9 methylation level at the Sry locus is finely tuned by the balance in activities between the H3K9 demethylase Jmjd1a and an unidentified H3K9 methyltransferase to ensure correct Sry expression. Here we identified the GLP/G9a H3K9 methyltransferase complex as the enzyme catalyzing H3K9 methylation at the Sry locus. Based on this finding, we tried to rescue the sex-reversal phenotype of Jmjd1a-deficient mice by modulating GLP/G9a complex activity. A heterozygous GLP mutation rescued the sex-reversal phenotype of Jmjd1a-deficient mice by restoring Sry expression. The administration of a chemical inhibitor of GLP/G9a enzyme into Jmjd1a-deficient embryos also successfully rescued sex reversal. Our study not only reveals the molecular mechanism underlying the tuning of Sry expression but also provides proof on the principle of therapeutic strategies based on the pharmacological modulation of epigenetic balance. Author summary In eukaryotes, DNA wraps an octamer of the core histones. Covalent modifications on the histones have diverse biological functions including transcriptional regulation. Histone H3 lysine 9 (H3K9) methylation is a hallmark of transcriptionally silenced chromatin. In mammals, the sex-determining gene Sry initiates testis differentiation in embryonic gonads. Sry expression in gonads is fine-tuned in both space and time. Here, we demonstrated that fine-tuning of Sry expression is achieved by the balance in activities between H3K9 demethylase and H3K9 methyltransferase. We found that the GLP/G9a complex is the enzyme catalyzing H3K9 methylation of Sry . Based on this finding, we tried to rescue the sex-reversal phenotype of the mutant mice by modulating the H3K9 methylation balance of Sry . We succeeded by modulating the H3K9 methylation balance not only with a genetic approach but also with a chemical approach using an inhibitor of GLP/G9a enzyme. Aberrant histone methylation levels are associated with diseases, including cancer, and intellectual disability. Our study provides proof for the principle of therapeutic strategies based on the pharmacological modulation of histone methylation balance.
【초록키워드】 Mutation, Diseases, Cancer, Genetic, Sex, molecular mechanism, activity, biological function, DNA, mice, intellectual disability, methyltransferase, Therapeutic strategies, phenotype, lysine, mutant, inhibitor, expression, Epigenetic, therapeutic strategy, Methylation, histone, administration, leads, balance, deficiency, Histones, locus, modulation, principle, enzyme, complex, transcriptional regulation, activities, proof, hallmark, mammals, Modification, chromatin, eukaryotes, heterochromatin, heterozygous, core histones, Sex determination, tuning, pharmacological, approach, Embryo, provide, demonstrated, reveal, embryonic, initiate, rescued, demethylase, histone methylation, modulating, transcriptionally, 【제목키워드】 Sex, mice, Methylation, balance, demethylase, modulating,