A Comprehensive Atlas of Testicular lncRNAs Reveals Dynamic Changes and Regulatory Networks During Sexual Maturation in Tibetan Sheep

Tibetan sheep, a dominant livestock species on the Qinghai-Tibet Plateau, is characterized by late sexual maturity and low reproductive efficiency. Although long non-coding RNAs (lncRNAs) are known to play critical regulatory roles in mammalian testicular development and spermatogenesis, their expression dynamics and functions in Tibetan sheep remain poorly understood. In this study, we integrated histological and transcriptomic analyses to profile testicular lncRNAs across three developmental stages: pre-pubertal (3 months), sexually mature (1 year), and adult (3 years). Histological examination showed progressive structural maturation of seminiferous tubules, accompanied by significant increases in testicular weight and serum testosterone levels. RNA sequencing identified 10,857 high-confidence lncRNAs and uncovered extensive reprogramming of the lncRNA transcriptome during sexual maturation, with 7784 lncRNAs differentially expressed between pre-pubertal and post-pubertal stages. Functional enrichment analyses of cis- and antisense-target genes indicated that these lncRNAs were involved in key biological processes, including cell cycle regulation, TGF-β and Hippo signaling pathways, extracellular matrix organization, glycolysis, and apoptosis. Co-expression network analysis further linked upregulated lncRNAs to spermatogenesis-related genes involved in processes such as sperm nuclear condensation (e.g., TNP1) and metabolic support (e.g., PFKP). Our findings demonstrated that lncRNAs coordinate testicular development and spermatogenesis in Tibetan sheep by modulating transcriptional networks, remodeling the cellular microenvironment, and reprogramming energy metabolism. This study provides the first comprehensive atlas of testicular lncRNAs in Tibetan sheep and offers novel insights into the epigenetic regulation of male reproduction in high-altitude mammals.