The impact of histone post-translational modifications in neurodegenerative diseases

Samantha N. Cobos, Seth A. Bennett, Mariana P. Torrente, Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2018, ISSN 0925-4439, doi:10.1016/j.bbadis.2018.10.019.

Several histone PTMs have been associated with FRDA. One of the main causes of FRDA is the triplet repeat expansion GAA responsible for the transcriptional silencing of the FXN gene. Lymphoid cell lines from FRDA patients revealed that H3K4me2 and H3K4me marks decreased in the area surrounding the triplet repeat expansion when compared to unaffected cells. Moreover, both human tissues and a transgenic mice model showed an overall decrease in H3K9ac levels accompanied by increases in H3K9me2 and H3K9me3 levels. Collectively, these changes in histone marks would lead to lowered transcription, strongly suggesting that this is part of the mechanism that defines FRDA pathology.
In FRDA, treatment with nicotinamide (vitamin B3), an HDAC inhibitor, resulted in upregulation of the FXN gene by way of decreasing H3K9me3 and H3K27me3 at the FXN gene, and consequently increasing histone acetylation in both H3 and H4. This revels a possible treatment for FRDA, especially when considering the widespread availability, tolerability and affordability of vitamin B3.

The impact of histone post-translational modifications in neurodegenerative diseases