IBYME   02675
INSTITUTO DE BIOLOGIA Y MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
THE PEPTIDYLPROLYL-ISOMERASE ACTIVITY OF FKBP52 IS REQUIRED TO ENHANCE NF-KB BIOLOGICAL ACTION
Autor/es:
DE LEO S, CAMISAY MF, GALIGNIANA MD, ERLEJMAN A
Reunión:
Conferencia; LXI Reunión Anual de SAIC; 2016
Resumen:
Nuclear Factor KappaB (NF-kB) is a transcription factor that regulates the expression of genes involved in inflammation, cell cycle and cell death. NF-kB aberrant activation is relevant in chronic inflammatory diseases and cancer promotion. Inactive NF-kB is primarily cytoplasmic, and translocates to the nucleus upon activation. High MW FK506-binding proteins (FKBPs) are Hsp90-binding proteins first related to steroid receptor action. A signature property for FKBPs is the peptidylprolyl isomerase (PPIase) activity. Previously, we reported that FKBP51 and FKBP52 modulate canonical NF-κB (p65/p50) biological actions in an antagonistic fashion. In this work, we studied the contribution of FKBP52-PPIase activity on NF-kB biological action at different steps of its activation cascade, i.e. transcriptional activation by gene reporter assay, p65 nuclear relocalization by indirect immunofluorescence, and p65 phosphorylation at Ser536 by Western blot. NF-kB nuclear translocation was favored by overexpression of FKBP52 in HEK293T cells treated for 1 h with TNFalpha, while a mutant lacking enzymatic activity (FKBP52 F130Y) showed a decreased nuclear translocation. Accordingly, FKBP52 favored p65 phosphorylation as demonstrated by Western blot with a specific antibody and a band shift after alkaline phosphatase treatment. FKBP52 showed a strong stimulating effect on PMA-induced NF-kB transcriptional activation. The relevance of the PPIase activity for this effect was indirectly evidenced by the lack of stimulation in cells treated with the inhibitor FK506 (tacrolimus), and confirmed by overexpression of two inactive PPIase mutants. In contrast to FKBP52, its homologous partner FKBP51 impaired p65 nuclear translocation and transcriptional activity, the PPIase activity and its association with Hsp90 via the TPR domain being not required. In summary, FKBP52 activates NF-kB signalling cascade at various steps, its PPIase activity playing a key role in this regulation.