Genome-Wide Identification and Characterization of the Wnt Gene Family in Donkey (Equus asinus): Phylogenetic Analysis and Expression Profiling

The Wnt gene family encodes highly conserved signaling molecules involved in vertebrate development, tissue homeostasis, and cell fate regulation. However, the evolutionary characteristics and potential biological functions of Wnt genes in the domestic donkey (Equus asinus) remain poorly understood. In this study, we performed the first genome-wide identification and comprehensive characterization of the donkey Wnt gene family. A total of 19 Wnt genes were identified, consistent with the conserved Wnt repertoire reported in other mammalian species. Phylogenetic and synteny analyses revealed strong evolutionary conservation of Wnt genes among mammals, particularly between donkey and horse, indicating conserved orthologous relationships within the genus Equus. Structural analyses showed that all donkey Wnt proteins contained the conserved cysteine-rich domain (CRD), whereas sequence variation was mainly concentrated in the N- and C-terminal regions. Transcriptomic analysis across 13 adult tissues revealed tissue-biased expression patterns, with Wnt3, Wnt5a, and Wnt4 showing relatively higher expression in the testis, epididymis, and skin, respectively, suggesting their potential involvement in reproductive regulation and tissue homeostasis. PPI network and GO enrichment analyses indicated potential associations between donkey Wnt proteins and conserved regulators involved in developmental processes, cell fate regulation, and Wnt signaling pathways. Integration of expression profiles with predicted interaction networks further suggested tissue-associated regulatory patterns among Wnt pathway components. Overall, this study provides a comprehensive resource for understanding the genomic organization, evolutionary conservation, and expression diversity of the donkey Wnt gene family, and offers insights into potential Wnt-mediated regulatory mechanisms in donkey biology.