Acute high folic acid treatment in SH-SY5Y cells with and without MTHFR function leads to gene expression changes in epigenetic modifying enzymes, changes in epigenetic marks, and changes in dendritic spine densities.

Epigenetics are known to be involved in various disorders, including neurobiological disorders like autism. Dietary factors such as folic acid can affect epigenetic marks using methylenetetrahydrofolate reductase (MTHFR) to metabolize folic acid to a one-carbon methyl group. As MTHFR mutations are frequent, it is curious as to whether excess folic acid, with or without functioning MTHFR, could affect gene expression, epigenetics, and neuromorphology. Here, we investigated gene expression and activity of epigenetic modifying enzymes, genome-wide DNA methylation, histone 3 modifications, and dendritic spine densities in SH-SY5Y cells with or without a knockdown of MTHFR and with or without an excess of folic acid. We found alterations to gene expression of epigenetic modifying enzymes, including those associated with disorders like autism. Grouping the epigenetic modifying enzymes by function indicated that gene expression was widely affected for genes that code for enzymes affecting DNA methylation, histone acetylation, histone methylation, histone phosphorylation, and histone ubiquitination when excess folic acid treatment occurred with or without the knockdown of MTHFR. MTHFR was significantly reduced upon excess folic acid treatment whether MTHFR was knocked-down or not. Further, methyl-CpG binding protein 2 expression was significantly decreased with excess folic acid treatment with and without proper MTHFR expression. Global DNA methylation decreased due to the knockdown alone while global hydroxymethylated DNA increased due to the knockdown alone. TET2 expression significantly increased with the MTHFR knockdown alone. Excess folic acid alone induced a decrease in TET3 expression. Excess folic acid induced an increase in dendritic spines without the MTHFR knockdown, but folic acid induced a decrease in dendritic spines when MTHFR was knocked-down. The knockdown alone also increased the dendritic spines significantly. Histone 3 acetylation at lysine 18 was significantly increased when excess folic acid was applied to cells with the MTHFR knockdown, as was histone 3 phosphorylation at serine 10. Broadly, our results indicate that excess folic acid, even with functioning MTHFR, could have detrimental effects on cells.

A 2x folic acid treatment affects epigenetics and dendritic spine densities in SHSY5Y cells.

Many diseases are now associated with aberrant epigenetics and gene expression changes. Epigenetics can be modified by factors like diet. One dietary factor, folic acid, is consumed in various forms including supplements, energy drinks, and fortified grains. It was hypothesized high levels of folic acid would affect gene expression and enzyme activity of chromatin modifying enzymes as well as dendritic spine densities in a commonly utilized neuron model, the SHSY5Y cell. Decreased MBD2 and MECP2 were discovered upon treatment of SHSY5Y cells with a 2x folic acid dose. Corresponding decreases in dendritic spines were apparent in the 2x folic acid treated cells as well. Activity of DNMTs and H3K4 HMTs was altered. Further, H3K4me1, H3K4me3, H3K9Ac, and global DNA methylation were decreased in the 2x folic acid treated cells. Further studies are warranted to determine if the effects of excess folic acid are detrimental to organismal physiology.

A high methyl donor diet affects physiology and behavior in Peromyscus polionotus.

Folic acid and other dietary methyl donors are widely supplemented due to their ability to prevent neural tube defects. Dietary methyl donors are also added to other consumables such as energy drinks due to energy-promoting attributes and other perceived benefits. However, there is mounting evidence that indicates developmental exposure to high levels of dietary methyl donors may have deleterious effects. We assessed whether behavior was affected in the social North American rodent species Peromyscus polionotus exposed to a diet enriched with folic acid, Vitamin B12, choline, and betaine/trimethylglycine(TMG). P. polionotus (PO) animals are very social and exhibit little repetitive behavior, particularly compared to their sister species, P. maniculatus. We assayed the effects of dietary methyl-donor supplementation on anxiety-like repetitive and social behaviors by testing young adult animals for novel cage behavior and in social interaction tests. Animals of both sexes exposed to the diet had increased repetitive behaviors and reduced social interactions. Males exposed to the diet became more aggressive compared to their control counterparts. Since methyl-diet animals were larger than control animals, DEXA scans and hormone analyses were performed. Animals exposed to the diet had increased body fat percentages and experienced hormonal changes typically associated with excess fat storage and anxiety-like behavior changes. Therefore, these data suggest the wide use of these dietary supplements makes further investigation imperative.