Molecular Characterization, Signaling Activity, and Expression Profiles of a Novel Prolactin Splice Variant (PRL-S) in Zhedong White Geese Across Reproductive States

Intense broodiness restricts egg production in Zhedong White Geese, with prolactin (PRL) being a key regulator. This study aimed to elucidate the role of PRL gene alternative splice variants in regulating broodiness in Zhedong White Geese. A total of 20 Zhedong White Geese at 400 days of age were selected and divided into two groups of 10 based on their physiological states: the laying period and the brooding period. Through bioinformatics and molecular biology approaches, PRL-L and PRL-S were identified and characterized. The results showed that PRL-S lacked a signal peptide and the first 57 amino acids at the N-terminus, leading to the disappearance of its first α-helix structure. Functional validation demonstrated that the recombinant PRL-S protein, prepared using a prokaryotic expression system, possessed physiological activity, including receptor binding and the activation of downstream signaling pathways. Furthermore, Real-time PCR and Western blot analyses revealed that the expression of both splice variants in the hypothalamic–pituitary–ovarian axis exhibited significant spatiotemporal specificity and was closely associated with reproductive states. This study revealed the molecular characteristics, in vitro functional activity, and expression patterns of PRL-S, providing new insights into the regulatory mechanisms of PRL.