MTHFD1 controls DNA methylation in Arabidopsis.

Area of Science:

• Plant Molecular Biology
• Epigenetics
• Metabolic Biochemistry

Background:

• DNA methylation is a key epigenetic mechanism for transcriptional silencing, often associated with repressive histone marks like H3K9me.
• Epigenetic regulation ensures genome stability and proper gene expression, but its sensitivity to metabolic status is not fully understood.

Purpose of the Study:

• To investigate the role of one-carbon metabolism in epigenetic silencing mechanisms in Arabidopsis thaliana.
• To identify genetic factors linking metabolic pathways to DNA methylation and histone modification.

Main Methods:

• Screening of a mutagenized Arabidopsis population for altered expression of a reporter gene (SDCpro-GFP) under epigenetic control.
• Characterization of the hypomorphic mutant mthfd1-1, including genetic analysis and biochemical assays.
• Genome-wide analysis of DNA methylation and histone modifications (H3K9me) in wild-type and mutant plants.

Main Results:

• Identification of the mthfd1-1 mutant affecting cytoplasmic methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase (MTHFD1), essential for one-carbon metabolism.
• mthfd1-1 mutants exhibit decreased oxidized tetrahydrofolates, accumulation of homocysteine and S-adenosylhomocysteine, leading to genome-wide DNA hypomethylation.
• Loss of H3K9me and derepression of transposons were observed, indicating impaired S-adenosylmethionine-dependent transmethylation, particularly affecting CMT3 and CMT2 pathways.

Conclusions:

• The study demonstrates that disruptions in one-carbon metabolism critically impact DNA methylation and epigenetic gene silencing in plants.
• Arabidopsis MTHFD1 is essential for maintaining DNA methylation patterns and epigenetic stability through S-adenosylmethionine-dependent transmethylation.
• Findings underscore the interconnectedness of metabolic and epigenetic networks and suggest potential relevance to human MTHFD1-associated diseases.