Molecular mechanisms underlying sexual precocity in Chinese mitten crab (Eriocheir sinensis): aldh1a1 regulates retinol metabolism via miRNAs in the hepatopancreas

Precocial Eriocheir sinensis, showing advanced sexual maturity, are a serious impediment to crab industry. The aim of this study was to identify miRNAs and its related pathways involved in regulation of precocity in E. sinensis. High-throughput sequencing was used to evaluate hepatopancreas of precocious and normal E. sinensis at the same period. A total of 101 differentially expressed miRNAs were identified as candidate target genes. KEGG analysis revealed retinol metabolism may contribute to the regulation of gonadogenesis. Aldehyde dehydrogenase 1 family member A1 (aldh1a1) was identified as the core gene in the retinol metabolism by gene expression, and subsequently, gene cloning was performed to further explore its function. The aldh1a1 gene was 1740 bp, including a 189 bp 5′ untranslated region (UTR), 75 bp 3′ UTR and a 1476 bp open-reading frame, encoding 491 amino acids. The corresponding protein is 87.98 % homologous in Portunus trituberculatus. The expression of aldh1a1 was highest in ovary, and then in the hepatopancreas. In addition, dual-luciferase reporter assay indicated that there was negative correlation between NW_020868524.1_2213 and aldh1a1. NW_020868524.1_2213 agomir treatment in the normal group increased testosterone and estradiol levels significantly, down-regulated aldh1a1 expression, and activated the retinol metabolism. By contrast, the administration of NW_020868524.1_2213 antagomir after a short-term induction of retinol resulted in increase in aldh1a1 expression, decrease in sex hormone levels, and inhibition in retinol metabolism. In short, NW_020868524.1_2213 in the hepatopancreas could activate the retinol metabolic pathway via aldh1a1, thus regulating precocious and gonadal development in E. sinensis. These findings would provide a potential pathway for decreasing crab precocity in practice.