Profiling chromatin accessibility responses to seasonal heat stress in Angora rabbit testes

Seasonal heat stress negatively impacts spermatogenesis, yet the underlying molecular mechanisms remain poorly understood. To investigate the epigenetic responses to heat stress in Angora rabbit spermatogenesis, we performed an Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) on testicular tissues collected during spring and summer.

High-quality sequencing data were obtained, yielding 196 to 310 million clean reads per sample with mapping rates exceeding 97%. Chromatin accessibility signals were predominantly enriched near transcription start sites, and principal component analysis (PCA) clearly segregated the spring and summer samples, revealing distinct epigenetic landscapes across seasons. We identified 416 differentially accessible chromatin regions (DARs), comprising 346 up-regulated and 70 down-regulated peaks in the summer group compared to the spring group. Motif analysis of these regions revealed enrichment of binding sites for transcription factors (TFs) such as E-box, MITF, and Usf2. Genes associated with these DARs were significantly enriched in reproduction-related biological processes and critical signaling pathways, including p53, TGF-beta, MAPK, Wnt, and mTOR. Integrating the ATAC-seq data with RNA-seq profiles identified 88 overlapping differentially expressed genes, among which BAX, CDK4, UBB, and TNP2 exhibited consistent or complementary alterations in both chromatin accessibility and gene expression. These key genes are intrinsically involved in spermatogenesis, stress response, and apoptosis, and are potentially regulated by the transcription factors identified in this study.

Our findings provide novel insights into the epigenetic regulation of testicular function under heat stress, highlighting essential candidate genes and pathways for further functional studies.