| Background:Migraine is a common primary neurological disorder characterized by moderate to severe pain intensity, unilateral localization, pulsating quality, recurrent headache attack,and aggravation by movement, which accompanied by nasea, vomiting, photophobia and phonophobia. Because of its heavy burden for individuals and society, migraine has been recognized as the sixth most disabling disease in the world by WHO. The complex mechanism of migraine is far from fully understood and it is still lacking biomarkers available for prediction of migraine susceptibility, differential diagnosis and the prediction of response to treatment. Epigenetic modulations are supposed to participate in etiology of migraine, but few clinical evidences support that DNA methylation and microRNA dysregulation are involved in migraine. Numerous studies suggest that receptor activity modifying protein 1 (RAMP1) is a key receptor subunit of calcitonin gene related peptide (CGRP) playing a critical role in migraine. However, genetic polymorphism studies and genome-wide associated studies failed to link migraine with these variations. In this study, we aimed to explore whether DNA methylation pattern at the promoter region of RAMP1 gene in peripheral leukocyte is associated with migraine, and identify differential expressions of circulating miRNAs (miR-382-5p and miR-188-5p) and mRNA of CGRP in peripheral blood of migraineurs.Methods:Blood DNA, RNA and serum miRNA from migriane patients and matching healthy controls were collected and extracted. After treated with bisulfate, subsequently DNA methylation levels at RAMP1 promoter region were measured using Sequenom Mass ARRAY systems. Differential expression of serum miR-382-5p and miR-188-5p, and mRNA of CGRP in peripheral blood were evaluated by quantitative real-time polymerase chain reaction.Results:A low methylation trend overall in migraine group was represented (total average methylation level:8.41% ±1.92% vs.9.90% ± 3.88%, p= 0.197). Stratification analysis showed that methylation level at (+25,+27,+31, related to the transcription start site) CpG unit was higher in migraineurs with migraine family history compared to those without (13.92% ± 5.97% vs.8.77% ± 6.61%, p= 0.034), and methylation level at (+89,+94, +96) CpG unit was lower in migraine female than that in healthy female (2.18% ± 1.91% vs.5.85% ± 5.41%, p= 0.02), but not among male participants. For female with methylation level at (+89,+94,+96) CpG unit below 3.50%, the probability of being a migraine patient was significantly higher than those with methylation level above the threshold (OR:7.313; 95%CI:1.439-37.164). Relative expression of serum miR-188-5P in piatents with postive migraine history descreased 4.2 fold compared to those with negative migraine history (p=0.106), and the similar trend was found in migraineurs during headache attack,5.54 fold lower than those outside of attack(p=0.132). Differential expression of serum miR-382-5p and mRNA of CGRP in peripheral blood were not observed.Conclusions:The study provides the first evidence that DNA methylation at RAMP1 promoter might play a role in migraine. A low methylation trend overall was presented in migraine subjects, and two CpG units were observed to link with positive migraine family history and female migraine, respectively. Lower methlytion level at (+89,+94,+96) CpG unit may be a risk of migraine in females. In addition, serum miR-188-5p, rather than miR-382-5p and CGRP mRNA, may be associated with headache attack and postive migraine history. Still, the results need larger samples to be further validated and the molecular mechanism underlying remains to be investigated. |
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