Structural and functional analysis of the glucocorticoid receptor multimerization: implications for human pathophysiology
- Autores: Alba Jiménez Panizo
- Directores de la Tesis: Eva Estébanez Perpiñá (dir. tes.), Pablo Fuentes Prior (codir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2021
- Idioma: inglés
- Tribunal Calificador de la Tesis: Marta Giralt i Oms (presid.), Francesc Xavier Gomis-Rüth (secret.), Ignacio Fita Rodríguez (voc.)
- Programa de doctorado: Programa de Doctorado en Biotecnología por la Universidad de Barcelona
- Materias:
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- Resumen
The glucocorticoid receptor (GR) is a ubiquitously expressed transcription factor that controls metabolic and homeostatic processes essential for life. Although numerous crystal structures of the GR ligand-binding domain (GR-LBD) have been reported, the functional oligomeric state of the full-length receptor (FL-GR), which is essential for its transcriptional activity, remains disputed. In this thesis dissertation we present six new crystal structures of agonist-bound GR-LBD, along with an extensive analysis of previous structural work. A catalog of 20 different dimeric arrangements have been identified from the structural studies (using X-ray crystallography and complementary in silico calculations) and biologically meaningful homodimers were corroborated by studying a battery of GR point mutants in selected areas crucial for GR-LBD self-assembly. In addition, GR mutants were analyzed using crosslinking and surface plasmon resonance assays in solution and quantitative fluorescence microscopy in living cells. Our results highlight the relevance of non-canonical dimerization modes for GR, especially of contacts made by loop L1-3 residues such as Tyr545. Additionally, we describe a second surface pocket placed in the LBD that can modulate GR activity by binding several endogenous and synthetic cholesterol derivatives. We have coined the term GR sensor site for this newly identified druggable pocket on the receptor. Our work unveils likely (patho)physiologically relevant quaternary assemblies of this nuclear receptor with important implications for glucocorticoid action and drug design.
