Whole transcriptomic analysis reveals the lncRNA-miRNA-mRNA regulatory mechanism underlying the heat-hardening formation in Mytilus coruscus

Abstract

Heat-hardening is a critical adaptation mechanism that enables the mussel Mytilus coruscus to endure high-temperature events caused by low tides and adverse weather condition. However, the molecular regulatory mechanism underlying heat-hardening remains unclear. Herein, we analyzed the whole transcriptome of heat-hardening M. coruscus to explore formation mechanism of heat-hardening. M. coruscus were treated with 27 °C for 5 days, 3 h per day, to promote heat-hardening formation, and sampled at 6, 8, 10, 12, 14, and 16 days. We identified 203 differentially expressed lncRNAs (DE-lncRNAs), 11 differentially expressed miRNAs (DE-miRNAs) and 207 differentially expressed mRNAs (DE-mRNAs). GO and KEGG enrichment analysis revealed that the DE-mRNAs were mainly enriched in arachidonic acid metabolism pathway, apoptosis pathway, NOD-like receptor signaling pathway and the platelet-activated pathway, WGCNA results suggested that arachidonic acid metabolism and cytochrome P450 were significantly correlated with heat-hardening during formation. PLA2 was identified as an essential gene in heat-hardening, with high node degrees, enriched in the arachidonic acid metabolism pathway and regulated by a lncRNA (MSTRG.113849.1) and a miRNA (novel_miR_425). MSTRG.113849.1-novel_miR_425-PLA2 relationship pairs were identified for heat-hardening in M. coruscus. Our finding suggests that miRNAs and lncRNAs play pivotal roles in heat-hardening by targeting PLA2, providing a mechanism for M. coruscus to adapt to heat stress, which also offers a mechanism to adapt to stressors arising from a rapidly changing oceanic environment.