PHOSPHORYLATION REGULATES THE FUNCTION OF ZEB1 TRANSCRIPTIONAL REPRESSOR.

PERRONE, ANA PAULA; LLORENS, MARÍA CANDELARIA ; CABANILLAS, ANA MARÍA

Buenos Aires

Congreso; SAIB -Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2013

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

ST-P05. PHOSPHORYLATION REGULATES THE FUNCTION OF ZEB1 TRANSCRIPTIONAL REPRESSOR Perrone AP, Llorens MC, Cabanillas AM. Dpto Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional Córdoba, CIBICI-CONICET. E-mail: aperrone@fcq.unc.edu.ar ZEB1 is a transcription factor important for the epithelialmesenchymal transition by which many tumors undergo metastasis. ZEB1 is phosphorylated but the role of phosphorylation(P) is unknown.Our studies show that a decrease in P-ZEB1 increases both DNA binding and transcriptional repression of ZEB1 target genes and that its ZD2 domain holds 4 phosphorylation sites (T851,S852,S853,T867). Functional assays with ZD2 mutants show that PMA, or IGF-1 (mediated by ERK) can prevent the transcriptional role of ZD2. GFP-ZD2 clones show that IGF-1 disrupted ZEB1 nuclear localization.Our aim is to expand the significance of P to full length ZEB1 (FLZEB1) and the importance of the T867 site. FLZEB1 mutated at all 4 sites repressed more the activity of gene targets than wtZEB1, which was not obtained by a single mutation T867A suggesting that the 4 sites are needed and a cooperative activation among them.Immunofluorescence of CHO cells transfected with ZEB1-T867A or ZEB1-T851A/S852A/ S853A/T867A show the mutants are unresponsive to IGF-1 (they remained nuclear) and that T867 controls cellular location of ZEB1. Transfections assays with ZD2-T867A, ZD2-T867E (P-mimetic) and ZEB1-T867A show that IGF-1 induces its effect through T867 and that ZEB1 has other IGF-1 responsive phosphosites.The results confirmed that ZEB1 biological role is regulated by P-ZEB1 would serve as an integrating factor of external signals.