Whole Transcriptome-Based Investigation of Testicular Developmental Differences in Kazakh Horses Across Age Stages

The reproductive performance of horses is closely associated with testicular development, which involves complex gene regulatory networks. As an important indigenous horse breed in China, the molecular mechanisms underlying the reproductive characteristics of Kazakh horses remain incompletely understood. This study employed whole transcriptome sequencing technology to analyze testicular tissues from Kazakh horses at different age stages, investigating gene expression differences and regulatory mechanisms during testicular development. Results revealed significant differential expression of 7,678 mRNAs, 4,569 long non-coding RNAs (LncRNAs), 4,148 circular RNAs (circRNAs), and 1,091 microRNAs (miRNAs) across developmental stages. GO and KEGG functional enrichment analyses demonstrated that commonly differentially expressed genes were primarily involved in biological processes (BP) such as biological regulation, cellular components (CC) like cell parts, molecular functions (MF) including binding activity, as well as signaling pathways such as the Wnt, PI3K-Akt, and mTOR signaling pathways. Furthermore, construction of a competitive endogenous RNA (ceRNA) regulatory network uncovered potential regulatory roles of non-coding RNAs in testicular development. This research provides theoretical insights into the molecular mechanisms of testicular development in Kazakh horses and identifies candidate molecular markers for genetic improvement of equine reproductive performance.