CircRNA-WNK2 acts as a ceRNA for miR-328a-3p to promote AANAT expression in the male rat pineal gland

Noncoding RNAs (ncRNAs), including miRNAs and circRNAs, which are expressed with a daily rhythm in the rat pineal gland, are associated with the regulation of melatonin secretion and other biological functions. However, the mechanisms of these molecules in the rat pineal gland are not yet fully understood. In this study, we found circR-WNK2 was highly expressed at night, which may be involved in the regulation of melatonin secretion through the ceRNA mechanism. By dual luciferase reporter, RNA pulldown, and FISH assays, we found that miR-328a-3p can target circR-WNK2 and the Aa-nat mRNA 3’UTR. Transfection experiments indicated that circR-WNK2 could competitively bind to miR-328a-3p, reduce miR-328a-3p expression, and promote Aa-nat gene expression and melatonin secretion. And by constructing an SCGx rat model, we found that ncRNAs expressed in the pineal gland was regulated by signals from the SCN. This finding supports the hypothesis that these noncoding RNAs may interact to shape the circadian rhythm through transcriptional processing in melatonin synthesis.