Dynamic changes in chromatin accessibility reveal the role of NF-Y targeting AURKB in mediating cell cycle during asynchronous oogenesis in the Chinese Alligator (Alligator sinensis).

The dynamics of chromatin accessibility that regulate oogenesis for the establishment of the female ovarian reserve in mammals have not been explored in reptiles with lifelong continuous oogenesis. Assays for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) were conducted to generate a chromatin accessibility landscape from gonadal samples from three critical stages of oogenesis in female Chinese alligators, which revealed a pronounced global decrease in chromatin accessibility across these developmental stages. Functional enrichment analysis demonstrated that differentially accessible regions were associated with genes involved in cell cycle regulation, meiosis, RNA binding, and cellular metabolism. Transcription factor footprinting identified krüppel-like factor (KLF) and specificity protein (SP) family members, POZ/BTB and AT-hook containing zinc finger protein 1 (PATZ1), and the nuclear transcription factor Y (NF-Y) complex (including subunits NFYA, NFYB, and NFYC) as core regulatory factors, with NF-Y binding sites exhibiting marked dynamic changes during development. Further analysis showed that NF-Y target genes are significantly enriched in critical processes such as cell cycle, mitosis, and meiosis, including key regulators Aurora Kinase A (AURKA) and AURKB. Experimental validation confirmed widespread ovarian expression of NFYA, NFYB, and NFYC, with AURKB expression strongly correlated with NF-Y protein levels. Dual-luciferase reporter assays demonstrated that NFYA significantly enhances AURKB promoter activity through two CCAAT-box elements near the transcription start site. This research depicts the chromatin accessibility dynamics during oogenesis of the Chinese alligator and pinpoints NF-Y as a crucial regulator of AURKB, thereby providing a mechanistic foundation for understanding reproduction and advancing conservation in this endangered species.