Development of a PET Probe Targeting Bromodomain and Extra-Terminal Proteins for In Vitro and In Vivo Visualization

<b>Background:</b> Bromodomain and extra-terminal (BET) proteins are critical regulators of gene transcription, as they recognize acetylated lysine residues. The BD1 bromodomain of BRD4, a member of the BET family, has emerged as a promising therapeutic target for various diseases. This study aimed to develop and evaluate a novel C-11 labeled PET radiotracer, [¹¹C]YL10, for imaging the BD1 bromodomain of BRD4 in vivo. <b>Methods:</b> [¹¹C]YL10 was synthesized and evaluated for its ability to bind to the BD1 bromodomain selectively. PET imaging studies were conducted in mice to assess brain penetration, pharmacokinetics, and selectivity. In vitro autoradiography and blocking experiments were performed to confirm the tracer's specificity for the BD1 domain. <b>Results:</b> [¹¹C]YL10 demonstrated good brain penetration, high selectivity for the BD1 bromodomain, and favorable pharmacokinetics in initial PET imaging studies. In vitro autoradiography and blocking experiments confirmed the specific binding of [¹¹C]YL10 to the BD1 domain of BRD4, further validating its potential as a targeted radiotracer. <b>Conclusions:</b> The development of [¹¹C]YL10 provides a new tool for studying BRD4 bromodomains using PET imaging technology. This radiotracer offers potential advancement in the diagnosis and research of neurodegenerative diseases and related disorders involving BRD4 dysregulation.