In Situ DNA/Protein Interaction Assay to Visualize Transcriptional Factor Activation

The chick embryo chorioallantoic membrane (CAM) represents a powerful in vivo model to study several physiological and pathological processes including inflammation and tumor progression. Nevertheless, the possibility of deepening the molecular processes in the CAM system is biased by the absence/scarcity of chemical and biological reagents, designed explicitly for avian species. This is particularly true for transcriptional factors, proteinaceous molecules that regulate various cellular responses, including proliferation, survival, and differentiation. Here, we propose a detailed antibody-independent protocol to visualize the activation and nuclear translocation of transcriptional factors in cells or in tissues of different animal species. As a proof of concept, DNA/cAMP response element-binding protein (CREB) interaction was characterized on the CAM tissue using oligonucleotides containing the palindromic binding sequence of CREB. Scrambled oligonucleotides were used as controls. In situ DNA/protein interaction protocol is a versatile method that is useful for the study of transcription factors in the cell and tissue of different origins.