The potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during aestivation in sea cucumber

The sea cucumber (Apostichopus japonicus) has become a good model organism for studying environmentally-induced aestivation by a marine invertebrate more recently. In the present study, we hypothesized that miRNA-200-3p may contribute to establish rapid biological control to regulate fatty acid metabolism during a estivation. The peroxisomal bi-functional enzyme (EHHADH) is a crucial participant of the classical peroxisomal fatty acid β-oxidation pathway, the relative mRNA transcripts and protein expressions of EHHADH were analyzed in intestine from sea cucumbers experienced long-term aestivation. Both mRNA transcripts and protein expressions of EHHADH in intestine decreased significantly during deep-aestivation as compared with non-aestivation controls. Analysis of the 3′ UTR of AjEHHADH showed the presence of a conserved binding site for miR-200-3p. Level of miR-200-3p showed an inverse correlation with EHHADH mRNA transcripts and protein levels in intestine, implicating miR-200-3p may directly targeted AjEHHADH by inducing the degradation of AjEHHADH mRNA in the aestivating sea cucumber, further dual-luciferase reporter assay validated the predicted role of miRNA-200-3p in regulating AjEHHADH. In order to further understand their regulatory mechanism, we conducted the functional experiment in vivo. The overexpression of miR-200-3p in sea cucumber significantly decreased mRNA and protein expression levels of AjEHHADH. Taken together, these findings suggested the potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during aestivation in sea cucumber.