CDK inhibitors p19INK4d and p21Cip1 protect fibroblasts from apoptosis induced by staurosporine

GUILLERMO VIDELA RICHARDSON; MARCELA CEPEDA; EDUARDO T. CANEPA; MARIA E. SCASSA

Mar del Plata, Buenos Aires

Congreso; XLIII Reunion Anual de la Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2007

Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular

CB-P67. CDK INHIBITORS p19INK4d AND p21Cip1 PROTECT FIBROBLASTS FROM APOPTOSIS INDUCED BY STAUROSPORINE Videla Richardson G, Cepeda M, Cánepa E, Scassa M. Laboratorio de Biología Molecular, Depto Química Biológica, FCEN-UBA, Buenos A i re s , Arge n t i n a . E - m a i l : mscassa@qb.fcen.uba.ar Apoptotic cell death and withdrawals from cell cycle are tightly coordinated. Essential mechanisms for regulation of the cell cycle also influence processes of cell death. An important mechanism for cell cycle control involves inhibition of cyclin dependent kinases (CDKs) by CDKs inhibitors that in mammalian cells fall into two families: Cip/Kip and INK4. The aim of this work is to elucidate the role of the structurally unrelated CKIs, p21Cip1 and p19INK4d, in apoptosis triggered by staurosporine. Northern blot analyses show that p19 and p21 are upregulated after staurosporine treatment in normal BHK fibroblasts. These inductions resulted dose dependent and started at 100 nM. Reporter gene experiments with a construct harboring 2250 bp of p19 promoter show that staurosporine was acting at the transcriptional level. Importantly the presence of caffeine, an ATM/ATR inhibitor abrogated staurosporine action upon p19 regulatory region. Clonogenic assays developed after 7 days post-treatment reveal that BHK cells stably overexpressing either p19 or p21 are more resistant to this proapoptotic inductor. Accordingly, these clonal cell lines exhibited reduced caspase-3 activity when compared to wild type or p19 deficient counterparts. Taken together these results suggest that the overexpression of a CKI can influence the sensitivity of cells to staurosporine mediated programmed cell death.