Characterization of avian LEAP2 transcripts with alternative polyadenylation and their 3'UTR stability

LEAP2 is a key regulator of appetite and metabolism, yet its transcriptional regulation, especially alternative polyadenylation (APA)‑derived transcript isoforms under different feeding states, remains largely uncharacterized in poultry. Here, combining tissue expression profiling, 5'/3'‑RACE, and dual‑luciferase reporter assays, we systematically characterized LEAP2 transcript isoforms in avian species and mice. Tissue profiling showed duck LEAP2 was highly expressed in liver, kidney and small intestine, whereas mouse Leap2 was mainly restricted to liver and small intestine. Two APA generated LEAP2 isoforms with identical coding sequences but distinct 3'UTR lengths (the long and short variants designated l‑3'UTR and s‑3'UTR, respectively) were identified in all tested avian species, and homologous isoforms existed in mice; the avian l‑3'UTR sequence was highly conserved across poultry species but divergent from the mouse ortholog. Feeding-status assays revealed post-prandial alterations in avian l-3'UTR-LEAP2 abundance. After fasting-refeeding, the l‑3'UTR isoform predominated in ducks (two‑thirds of total transcripts), whereas mouse Leap2 was unresponsive to feeding. Dual-luciferase assays demonstrated species-dependent 3'UTR stability. The s-3'UTR was more stable in chicken and quail, while l-3'UTR was more stable in ducks. Mechanistically, RNA-binding proteins (RBPs) PUM2 and ZFP36 were validated to modulate l‑3'UTR stability, and two miRNAs (gga‑miR‑2188‑3p, gga‑miR‑190a‑3p) were confirmed to target the 3'UTR and regulate LEAP2 expression in hepatocytes. Collectively, this study identifies conserved APA‑derived LEAP2 3'UTR isoforms in poultry with species‑specific stability co‑regulated by RBPs and miRNAs, laying a basis for further mechanistic investigation of LEAP2 in avian energy homeostasis.