A Study of JUN's Promoter Region and Its Regulators in Chickens

Background: The Jun proto-oncogene (JUN), also referred to as C-JUN, is an integral component of the JNK signaling pathway, which is crucial for the formation and differentiation of spermatogonial stem cells (SSCs). Investigations into the transcriptional regulation of chicken JUN can offer a molecular foundation for elucidating its mechanistic role in SSCs. Methods: In this study, we successfully cloned a 2000 bp upstream sequence of the JUN transcription start site and constructed a series of pGL3 recombinant vectors containing JUN promoters of varying lengths. Results: We verified the promoter activity of the 2000 bp upstream sequence by assessing the fluorescence intensity of DF-1 and identified the promoter activities of different regions via dual-luciferase assays. The transcription of JUN and its promoter region spanning -700 to 0 bp was modulated by an activator of the JNK signaling pathway. Bioinformatics analysis revealed that this -700 to 0 bp region was highly conserved among avian species and predicted the presence of binding sites for Wilms tumor 1 (WT1) and CCAAT/enhancer binding protein alpha (CEBPA). The JNK signaling pathway activator was found to upregulate the expression of these transcription factors in DF-1 cells. Through the deletion of binding sites and the overexpression of WT1 and CEBPA, we demonstrated that WT1 inhibited the transcription of JUN, while CEBPA promoted it. Conclusions: In conclusion, the -700 to 0 bp region is the key region of the JUN promoter, with WT1 inhibiting JUN transcription. The results of the study not only provide ideas for exploring the regulatory mechanism of JUN in chicken SSCs, but also lay an important foundation for the study of avian SSCs.