p19INK4d TRANSLOCA AL NÚCLEO Y DISMINUYE LA APOPTOSIS LUEGO DE LA IRRADIACIÓN CON UV EN CÉLULAS NEURONALES.

CERUTI, J.M; SCASSA, M; SIRKIN,PABLO; CÁNEPA, E.T

Mar del Plata. Argentina.

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigaciones Clínicas (SAIC); 2003

SAIC

We have previously demonstrated that overexpression of p19INK4d, a member of the INK4 family of inhibitors of CDK4/6, enhanced repair of a UV damaged DNA suggesting a posible link to the manteinance of genome integrity. The aim of this work is to determine the subcelular localization of p19 before and after treatment with genotoxic agents and its mechanism of action. Human neuroblastome cells were irradiated or not  with 20 mJ/cm2 of UVC and inmunocitochemical assays were performed making use of antip19 and antiIg-FITC antibodies. p19 is detectable on 43% of control cells and is citoplasmatic in 93% of these cells. On the other hand, 24h after UV irradiation the percentage of cells that express p19 increased, and we could observed a nuclear translocation from 36h with a maximum at 48h (75% with p19 and in 60% nuclear). 72h after UV irradiation there are less cells that express p19 (55%) and it is mainly in the citoplasm. We analized the effect of p19 on apoptosis  by determining the activity of caspase-3 in cells that overexpress p19 or an antisense to p19 and that were irradiated with UV. The enzimatic activity increased in irradiated cells (275%) and was higher in those with inhibited expression of p19 (305%). However, in cells that overexpress p19 the activity of caspase-3 slightly overcome the basal level (120%). The overexpression of a mutated CDK4 that is unable to bind INK4, didn’t affect the antiapoptotic effect of p19. These results suggest that, the insult of a genotoxic agent and/or the detection of the genomic damage, would induce the expression of p19INK4d and its nuclear translocation promoting the DNA repair and reducing the apoptosis. This effect of p19 would be independent of its interaction with CDK4/6.