An estradiol-17 beta/miRNA-26a/cyp19a1a regulatory feedback loop in the protogynous hermaphroditic fish, Epinephelus coioides

摘要

Cyp19a1a is a key gene responsible for the production of estradiol-17 beta (E-2), the main functional estrogen and a major downstream regulator of reproduction in teleost fish. It is widely known that CYP19 gene expression, aromatase activity, and E-2 production can influence gonadal differentiation and sex reversal in teleost fish, but the feedback mechanisms whereby E-2 regulates Cyp19a1a remain poorly understood, especially regarding the potential roles of endogenous small RNA molecules (miRNAs). Here, we identified miR-26a-5p as a regulatory factor of its predicted target gene (Cyp19a1a). In vitro and in vivo studies showed that miR-26a-5p can decrease Cyp19a1a expression. Furthermore, high doses of E-2 act as a repressor of miR-26a-5p. This study proposes a regulatory feedback loop whereby E-2 regulates Cyp19a1a through miR-26a-5p, and suggests that this positive feedback is an important aspect of the control of E-2 production.