Dynamic N6-methyladenosine modification of lncRNA modulated by METTL3 during bacterial disease development in an echinoderm.

Long non-coding RNAs (lncRNAs) are novel functional non-coding RNAs which engaged in many aspects of biological processes. N6-methyladenosine (m6A) as a kind of abundant epitranscriptomic modification in eukaryotes, plays important roles in regulation of gene expression for various physiological functions. Our previous study demonstrated that sea cucumber lncRNAs were differentially expressed during bacterial infection. However, whether the post-transcriptional regulation of lncRNAs influenced by m6A modification in sea cucumbers with different stages of skin ulceration syndrome (SUS) are largely unknown. Here, we generated the genome-wide map of m6A lncRNAs in SUS-diseased and SUS-resistant sea cucumbers for the first time, revealed that m6A levels in lncRNAs were mainly upregulated in SUS-resistant group. Intriguingly, most of the m6A lncRNAs showed a positive correlation between the expression levels and m6A levels based on conjoint analysis, suggesting that m6A modification on a lncRNA may contribute to its RNA stability. Furthermore, the host genes of lncRNAs with dysregulated m6A peaks were enriched in immune pathway. More importantly, methyltransferase METTL3 was required for m6A methylation modification and played positive roles in lncRNA expression. Collectively, this study presents the comprehensive characters of m6A lncRNAs in marine invertebrate. These m6A modified lncRNAs may be served as potential regulators associated with SUS and provide a promising avenue for disease therapy through targeting METTL3.