The critical role of m6A methylation in the pathogenesis of Graves' ophthalmopathy.

PURPOSE: To investigate the role of N6-methyladenosine (m6A) RNA modification in the pathogenesis of Graves' ophthalmopathy (GO).

METHODS

Surgically excised extraocular muscles from 7 patients with GO and 5 subjects without GO were used. The global m6A levels in the specimens were determined using an m6A RNA methylation quantification kit. RNA sequencing (RNA-seq) was used to analyze the molecules involved in the regulation of m6A RNA methylation and the differential expression of mRNAs between the two groups (4 eyes, respectively). The expression of m6A RNA modification genes was evaluated by real-time PCR. The functional implications of the gene alterations between the GO and control specimens were determined by Gene Ontology analysis.

RESULTS

The m6A level was significantly increased in the specimens of GO patients compared to the control specimens (P < 0.05). The expression of m6A methylation regulators, such as WT1 associated protein (WTAP), alkylation repair homolog protein 5 (ALKBH5), E74 like ETS transcription factor 3 (ELF3), YTH N6-methyladenosine RNA binding protein 2 (YTHDF2), YTHDF3 and YTH domain containing 2 (YTHDC2), was significantly upregulated (P < 0.05). Gene Ontology enrichment analysis showed that the most highly upregulated genes and biological pathways were related to the immune response and inflammatory processes such as lymphocyte activation, leukocyte differentiation, cytokine production and cytokine-mediated signaling pathways.

CONCLUSIONS

Our results suggest that m6A methylation may play a critical role in the pathogenesis of GO and that targeting genes that regulate m6A methylation may provide a new therapeutic approach for GO.