%0 Journal Article
%T Tau and Caspase 3 as Targets for Neuroprotection
%A Anat Idan-Feldman
%A Regina Ostritsky
%A Illana Gozes
%J International Journal of Alzheimer's Disease
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/493670
%X The peptide drug candidate NAP (davunetide) has demonstrated protective effects in various in vivo and in vitro models of neurodegeneration. NAP was shown to reduce tau hyperphosphorylation as well as to prevent caspase-3 activation and cytochrome-3 release from mitochondria, both characteristic of apoptotic cell death. Recent studies suggest that caspases may play a role in tau pathology. The purpose of this study was to evaluate the effect of NAP on tau hyperphosphorylation and caspase activity in the same biological system. Our experimental setup used primary neuronal cultures subjected to oxygen-glucose deprivation (OGD), with and without NAP or caspase inhibitor. Cell viability was assessed by measuring mitochondrial activity (MTS assay), and immunoblots were used for analyzing protein level. It was shown that apoptosis was responsible for all cell death occurring following ischemia, and NAP treatment showed a concentration-dependent protection from cell death. Ischemia caused an increase in the levels of active caspase-3 and hyperphosphorylated tau, both of which were prevented by either NAP or caspase-inhibitor treatment. Our data suggest that, in this model system, caspase activation may be an upstream event to tau hyperphosphorylation, although additional studies will be required to fully elucidate the cascade of events. 1. Introduction NAP is an 8 amino acid peptide, which was identified as an active neuroprotective fragment of activity-dependent neuroprotective protein (ADNP) [1]. NAP was found to be neuroprotective in various in vivo and in vitro models of neurodegeneration [2]. NAP treatment was shown to reduce two major pathological markers¡ªtau hyperphosphorylation [3¨C5] and caspase-3 activation/apoptosis [6, 7]. Hyperphosphorylated and aggregated tau, originally detected in Alzheimer¡¯s disease (AD) brains by Grundke-Iqbal and colleagues [8], is a hallmark of a group of diseases, generally referred to as ¡°tauopathies¡± which differ from each other by genetic background and by additional pathological and phenotypic characteristics [9]. Tau is a microtubule-associated protein (MAP) which promotes microtubule stabilization. The first study that reported disassembly of microtubules from AD brain due to the abnormal hyperphosphorylation of tau was by Iqbal et al. [10]. Hyperphosphorylated tau loses its microtubule affinity causing a change in microtubule dynamics towards disassembly [11¨C16] and further accumulation of aggregated tau. Alonso et al. originally showed that AD abnormal hyperphosphorylation of tau causes not only loss of function but
%U http://www.hindawi.com/journals/ijad/2012/493670/