Preliminary investigation of methylation status of microRNA-124a in spinal cords of rat fetuses with congenital spina bifida.

Objective: We investigated the expression of microRNA-124a and its methylation status in the spinal cords of rats with congenital spina bifida versus rats with normal fetuses.

Methods: Real-time quantitative reverse transcription-polymerase chain reaction was used to compare the expression of microRNA-124a in the spinal cords of 42 rats with all-trans retinoic acid induced congenital spina bifida and 42 rats with normal fetuses. The DNA methylation status in the promoter region of miRNA-124a was detected using methylation specific-PCR.

Results: Compared with rats with normal fetuses, expression of microRNA-124a was significantly decreased in rats with congenital spina bifida fetuses. The percentages of spinal cords with DNA hypermethylation in the microRNA-124a promoter were 81% and 14% in the congenital spina bifida and normal control groups, respectively. The difference was statistically significant. Further apoptosis testing revealed increased apoptosis cell numbers in the congenital spina bifida samples. Meanwhile, the phosphorylated mitogen-activated protein kinase protein expression level dramatically decreased in the congenital spina bifida samples.

Conclusion: Aberrant DNA methylation was responsible for down-regulation of microRNA-124a by regulating the mitogen-activated protein kinase pathway, suggesting that microRNA-124a is a potential diagnostic biomarker in congenital spina bifida.