Selective signaling pathways participate in the regulation of the biological role of ZEB1

LORENZATTI, GUADALUPE; CABANILLAS, ANA MARIA

Los Cocos, Cordoba.

Congreso; The First South American Spring Symposium in Signal Transduction and Molecular Medicine (SISTAM); 2010

SISTAM

SELECTIVE SIGNALING PATHWAYS PARTICIPATE IN THE REGULATION OF THE BIOLOGICAL ROLE OF ZEB1     ZEB1 is highly involved in metastasis by repressing E-cadherin. We reported that hypo-phosphorylated (PO4) ZEB1 represses more strongly its target genes and that the PO4 sites lie in its C-term, ZD2. Previous data showed that IGF-1 regulates ZEB1. We aimed to identify key PO4 sites of ZEB1 and to study which IGF1 downstream pathways, PI3K or MEK/ERK, are involved in ZEB1 role. We generated 3 blocks of ZD2 mutants (M). EMSA & reporter assays were used to test binding and biological role of M. Control ZD2wt or the M and E-cadherin or ZEB1-luciferase promoters were transfected to CHO-K1 cells. ZD2-2 M did not change promoters activities respect to ZD2wt but, ZD2-1A, -1B, -3A and -3C repressed luciferase more than ZD2wt. Incubation w/MEK/ERK or PI3K inhibitors increased the repression induced on ZEB1 promoter by ZD2wt and ZD2-2 M, but not by the other M. No higher repression was induced by LY294002 on E-cadherin promoter. Treatment w/ a PKC activator lowered repression induced by ZD2wt but not by ZD2-1 and -3. These unresponsive M did not increase their binding to ZEB1 target genes after treatment w/ alk. phosphatase (CIP) in EMSA. Our results point that M ZD2-1A, B & -3A, C harbor key ZEB1 PO4 sites which are likely targets of MEK/ERK pathway for the repression of E-cadherin by ZEB1