‘H3K27me3 has been recognized as an epigenetic marker during neuronal differentiation and folate supplementation has protective effects against neural tube defects.’
is believed to have protective effects
against NTDs as it plays an important role in cell proliferation,
differentiation and transcriptional regulation of genes. Past studies have
demonstrated that prenatal folic acid supplementation could reduce risk of
NTDs by nearly 70%, though the exact mechanism is not yet clear.
Research in rats was
undertaken to evaluate the association between the H3K27me3 gene which is
believed to be crucial in the regulation of neuronal differentiation and ACat2
(Acyl-coenzyme a-cholesterol acyltransferase 2), to study the protective
mechanism of folic acid (FA) in neural tube defects. The ACat2 gene codes for a
protein that is involved in folate metabolism.
- The study
involved 18 female rats, who were randomly divided into 3 groups: healthy
control, NTD (Neural Tube Defect) group and FA (Folic Acid) group. They were mated with male rats, and the
day the rats became pregnant was considered as 'embryonic day 0'.
- The FA
group was given supplementation of folic acid two weeks prior to
pregnancy. The other two groups were fed with regular food. Both the NTD
and FA groups were administered all-trans retinoic acid (ATRA) on
embryonic day 10 to induce neural tube defects.
embryonic day 15, neural stem cells (NSCs), the cells that will form the
nervous system, were isolated from the rat fetuses and cultured, and cell
proliferation was measured using CCK-8 assay method. FA level in the
embryonic neural tube was analyzed by ELISA (Enzyme-Linked
Immuno Sorbent Assay).
staining method was used to identify primary and differentiated NSCs.
- Immunofluorescence and confocal
microscopy were used to measure the
relative expression of H3K27me3. The total protein of NSCs was quantified
by the Western blot analysis method.
relative expression of ACat2 mRNA was calculated using quantitative reverse
transcription PCR (qRT-PCR).
- The relationship between H3K27me3 and FA and ACat2
levels was found using Spearman rank correlation test.
- Once the
NSCs were cultured, they formed numerous Nestin-positive neurospheres,
which differentiated into NSE-positive neurons and GFAP-positive
astrocytes after 5 days.
- It was
seen that the FA level in FA group was significantly higher as compared to
NTD group (P < 0.05), but when compared with controls, it was
found to be significantly lower (P < 0.05).
also demonstrated that FA
improved the impaired proliferation and differentiation ability of NSCs.
H3K27me3 level was found to be highest in the NTD group, followed by the
FA group and was the least in the control group.
- The ACat2
protein level in NTD group was significantly lower as compared to the
control group (P < 0.05), and was found to be significantly
higher after FA fortification (P < 0.05). The ACat2 protein level
in FA group was found to be significantly lower when compared to control
group (P < 0.05).
expression was found to be negatively correlated with the FA level and ACat2 level in the embryonic neural
results reiterate the importance of folic acid in preventing neural tube
defects in the fetus. FA supplementation might protect developing nerve
cells by reducing H3K27me3 expression which in turn increases ACat2 level.
- Zhai S. The association and significance of H3K27me3 and a folate metabolic gene ACat2 in neural tube defects.
Nutrition Journal 2016; 15:95 DOI: 10.1186/s12937-016-0212-7