Transcriptomic profiling of the donkey endometrium reveals dynamic molecular transitions across the estrous cycle

Abstract

The endometrium undergoes extensive cyclical remodeling essential for reproductive success; however, the molecular mechanisms governing these processes in donkeys (Equus asinus) remain poorly characterized. To address this gap, we performed high-throughput RNA sequencing on endometrial tissues collected from Dezhou donkeys (n = 16) at four post-ovulation stages: Day 0 (ovulation), Day 3 (early luteal), Day 7 (mid-luteal), and Day 18 (late luteal/pre-luteolysis). Differential gene expression analysis, Gene Ontology enrichment, and KEGG pathway mapping were conducted to characterize temporal transcriptomic dynamics. We identified 2,474, 6,548, and 1,288 differentially expressed genes in Day 0 versus Day 3, Day 0 versus Day 7, and Day 0 versus Day 18 comparisons, respectively. A biphasic transcriptional pattern emerged: transient suppression of immune and cytokine signaling pathways at Day 3 was followed by robust activation of TNF, NF-κB, PI3K-Akt, and extracellular matrix–receptor interaction pathways by Day 7, consistent with progesterone-driven stromal proliferation and tissue remodeling. By Day 18, enrichment of cytochrome P450, steroid hormone biosynthesis, and amino acid metabolism pathways indicated metabolic reprogramming associated with luteal regression. This study provides the first comprehensive temporal transcriptomic atlas of the donkey endometrium, revealing conserved endocrine–immune–metabolic regulatory networks comparable to those in mares and cattle. These findings establish a molecular foundation for developing precision strategies to improve uterine health, fertility management, and assisted reproductive technologies in donkeys.