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

## TL;DR

This study maps lncRNAs in Tibetan sheep testes, revealing how these molecules regulate sexual maturation and testicular development.

## Contribution

The first comprehensive atlas of testicular lncRNAs in Tibetan sheep, uncovering their role in regulating sexual maturation and spermatogenesis.

## Key findings

- 10,857 high-confidence lncRNAs were identified, with 7,784 showing differential expression during sexual maturation.
- lncRNAs regulate key processes like cell cycle, TGF-β signaling, extracellular matrix organization, and glycolysis during testicular development.
- Co-expression networks link lncRNAs to genes critical for sperm nuclear condensation and metabolic support.

## Abstract

Tibetan sheep are vital to the economy of the high-altitude Qinghai–Tibet Plateau, but their late sexual maturity and low reproductive rates pose a challenge for local herders. To understand this issue, we explored the process of testicular development and sperm production during their maturation. We focused on a class of genetic molecules known as long non-coding RNAs (lncRNAs), which function as master control switches, regulating the activity of other genes. By comparing testes from young, sexually mature, and adult sheep, we discovered that the tissue undergoes major structural transformations, accompanied by dramatic changes in the activity of thousands of lncRNAs during puberty. Our findings show that these lncRNAs help direct sexual maturation by turning key genes on and off. They coordinate essential steps in testicular development, such as cell proliferation, communication between cells, and energy metabolism required for sperm formation. This research provides the first comprehensive map of lncRNAs in the Tibetan sheep testis. It reveals new insights into the molecular mechanisms behind their sexual maturation, offering a foundation for future strategies to improve their reproductive efficiency.

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.