Discovery of a First‐in‐Class Dual‐Function TLX Activator by Microscale Library Synthesis and Direct‐to‐Biology Screening
Tanja Stiller, Romy Busch, Giuseppe Faudone, Felia C. Haffelder, Jan Vietor, Arthur Kardanov, Úrsula López‐García, Arne Hackspacher, Georg Höfner, Vasily Morozov, Susanne F. Koch, Julian A. Marschner, Daniel MerkABSTRACT
The tailless homolog (TLX) is a transcription factor with dual transcriptional repressor and activator properties and is thought to govern neural stem cell (NSC) and retinal progenitor cell homeostasis by maintaining a balance of proliferation and differentiation in these unique cell populations. TLX modulation may offer pharmacological control over neurogenesis and retinal cell development with therapeutic potential in degenerative pathologies, but TLX ligands to explore this concept are lacking. Here, we employed an evolution‐inspired ligand development approach with microscale synthesis and direct‐to‐biology testing to obtain potent activators of TLX’s repressor function and its transcriptional activity on the TLX‐activating element (TAE). Ligands promoting TLX's repressor or activator properties differently affected receptor dimerization and coregulator recruitment, providing a molecular basis for TLX modulation. In transcriptomic and phenotypic studies, TAE activation induced cellcycle gene programs and promoted cell cycle entry of terminally differentiated retinal pigment epithelial cells ex vivo, supporting the regenerative potential of TLX agonists.