RESUMO
The cyclic AMP-responsive element binding protein (CREB) is a posttranslationally activated transcription factor that has been implicated in numerous brain functions including cell survival. In this study we investigated whether CREB overexpression using transient transfection of a pAAV/CMV-CREB plasmid altered neuronal cells' susceptibility to apoptosis. We found that elevated CREB protein inhibited apoptosis induced by okadaic acid. At least part of this effect is critically dependent on prolonged Ser133 phosphorylation, as a directed mutation at this site decreased CREB-induced protection. These results suggest that CREB is a survival factor for neuronal cells and that treatments aimed at augmenting CREB phosphorylation in the brain may be neuroprotective.
Assuntos
Sobrevivência Celular , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Neurônios/fisiologia , Animais , Apoptose/efeitos dos fármacos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Expressão Gênica , L-Lactato Desidrogenase/metabolismo , Ácido Okadáico/farmacologia , Células PC12 , Fosforilação , Fosfosserina/metabolismo , Ratos , TransfecçãoRESUMO
Activating transcription factor (ATF-2) is a basic region-leucine zipper transcription factor that can mediate a diverse range of transcriptional responses including those generated by various forms of cellular stress. Activation of ATF-2 in response to these stimuli requires post-translational modification, in particular the phosphorylation of Thr69 and Thr71. To investigate whether ATF-2 activation also has a role in neuronal apoptosis, immunocytochemistry using a phospho-specific ATF-2 (Thr71) antibody was carried out in the 21 day old rat brain following a unilateral hypoxic-ischemic (HI) insult and PC12 cells cultured in the presence of okadaic acid. In both models a dramatic increase in phosphorylated ATF-2 was found within cells undergoing apoptosis.
