KEY REGULATORS OF P19INK4D IN RESPONSE TO DNA DAMAGE AND CELLULAR PROLIFERATION

CARCAGNO, ABEL; CÁNEPA, EDUARDO

Pinamar.

Congreso; XLI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2005

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

p19INK4 is a member of the INK4 family of proteins that regulate G1/S cell cycle transition by inhibiting the pRb kinase activity of CDK 4. We demonstrated that p19 a) is periodically expressed in a E2F-dependent manner b) its promoter presents binding sites for NFkB, c) is involved in DNA repair, d) is induced by UV irradiation. Little is known about the turn over of the signal of E2F and our results suggest that p19 could be involved in the negative feedback of E2F. The factors involved in p19 induction by UV remain elusive. The aims of the present work consist in 1) elucidate if p19 is involved in the negative feedback of E2F, 2) verify if NFkB and E2F participate in the induction of p19 in UV irradiated cells. To approach objective 1 we performed EMSA assays to assess the relative affinity of E2F for consensus sequences and p19 promoter sequences. E2F protein displayed a higher affinity for the consensus sequence than for p19 promoter elements. We compared the kinetics of cyclin E induction and p19, and observed a delay in p19 expression in comparison to cyclin E. To approach objective 2 we overexpressed NFkB in fibroblast and observed an induction of p19. p19 induction by UV irradiation was not modified by treatment with NFkB inhibitors but significantly decreased by E2F-decoy transfection. These results demonstrate that 1) p19 could be involved in a mechanism of negative feedback of E2F. 2) the UV induction of p19 is mediated by E2F and not by NFkB.