Functional Role of Glycogen synthase Kinase-3? on Glucocorticoid-mediated signaling

• Autores: Camila Rubio Patiño
• Directores de la Tesis: Daniel Iglesias i Serret (dir. tes.), Gabriel Pons i Irazazábal (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2012
• Idioma: inglés
• Tribunal Calificador de la Tesis: Albert Tauler Girona (presid.), Beatriz Bellosillo Paricio (secret.), L. Anel (voc.)
• Materias:
  • Ciencias de la vida
    • Biología celular
      • Cultivo celular
    • Biología molecular
  • Ciencias médicas
    • Medicina interna
      • Endocrinología
• Enlaces
  • Tesis en acceso abierto en:  TDX  Dipòsit Digital de la UB  TESEO 
• Resumen

  • Glucocorticoids (GC) induce cell cycle arrest and apoptosis in different cell types and therefore are widely used to treat a variety of diseases including autoimmune disorders and cancer. This effect is mediated by the GC receptor (GR), a ligandactivated transcription factor that translocates into the nucleus where it modulates transcription of target genes in a promoter-specific manner. Glycogen synthase kinase-3 (GSK3) regulates GR response by genomic and nongenomic mechanisms, although the specific role of each isoform is not well defined. We used GSK3 pharmacological inhibitors and isoform-specific small interfering RNA to evaluate the role of GSK3 in the genomic regulation induced by GC. The study was made in cell lines from different origin. GSK3 inhibition reverted GC-induced apoptosis by preventing GC-dependent MCL-1 downregulation and caspase-3 and -9 activation. GSK3 inhibition also resulted in the reduction of GC-induced mRNA expression of GC-induced genes such as BIM, HIAP1, and GILZ. Knockdown of GSK3? but not GSK3? reduced endogenous GILZ induction in response to dexamethasone and GRdependent reporter gene activity. Interestingly, GSK3 inhibition did not affect GCinduced transrepression. Chromatin immunoprecipitation experiments revealed that GSK3 inhibition impaired the dexamethasone-mediated binding of GR and RNA polymerase II to endogenous GILZ promoter through a mechanism that affects GR protein localization by decreasing early GR nuclear levels. These results indicate that GSK3? is important for GR transactivation activity and that GSK3? inhibition suppresses GC-stimulated gene expression. Furthermore, we show that genomic regulation of the GR by GSK3 occurs through a mechanism not involving known GSK3? phosphorylation sites. We propose that GC-dependent transcriptional activation requires functional GSK3? signaling and that altered GSK3? activity influences cell response to GC.