Multiple kinases are involved in p19INK4d induction and phosphorylation in response to genotoxics

OGARA, M. F.; MARAZITA M.C.; SCASSA, M. E.; CÁNEPA, E.T.

Rosario, Santa Fe, República Argentina

Congreso; XLII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB); 2006

SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB)

p19INK4d belongs to a family of cyclin-dependent kinase inhibitors that arrests cells in G1 interacting with CDK4/6. This protein participates in the cellular response to genotoxic stress, enhancing DNA repair and lowering apoptosis. Upon genotoxic insult, p19 is induced and subject to phosphorylation. As p19 phosphorylation is necessary for its role in DNA repair, we sought to characterize the signal transduction pathways leading to p19 activation and induction in WI38 diploid human fibroblasts exposed to the following genotoxic agents: UVC irradiation, the antitumoral cisplatin or beta-amyloid peptide. Northern blot analysis and immunoprecipitation assays following metabolic labeling with [32P]orthophosphate revealed that inhibition of ATM/ATR by caffeine 5 mM or specific inhibition of Chk1 blocks p19 induction and phosphorylation. Depending on the type of DNA lesion, impairment of Chk2 activity suppressed p19 phosphorylation without affecting its mRNA levels. None of the studied kinases MAPK, PI3K, PKA o CDKs seem to be implicated in the regulation of p19 in response to DNA damage. However, PKA or CDKs activity abrogation, partially or totally, respectively, blocked its phosphorylation. Our results demonstrate that, apart from ATM/ATR activation, different mechanisms would exist for the control of the expression and activity of p19 that vary according to the type of injury.