Effect of Gnmt overexpression on histone methylation abundance in Drosophila melanogaster photoreceptor cells

Histone methylation is influenced by the availability of the universal methyl donor S-adenosyl methionine (SAM) and the byproduct of SAM-depednent methylation: S-adenosylhomocysteine (SAH), a potent inhibitor of histone methyltransferases. Glycine-N-methyltransferase (Gnmt) regulates the availability of SAM and SAH by methylating glycine to produce sarcosine.

Both Gnmt and SAH are increased in the aging eye, therefore we hypothesize that an increase of Gnmt decreases histone methylation. To test this hypothesis, CUT&RUN was performed on multiple histone methyl marks in photoreceptor nuclei from flies that overexpress Gnmt in the eye versus control.