Resveratrol prevents antibody-induced apoptotic death of retinal cells through upregulation of Sirt1 and Ku70

<p>Abstract</p> <p>Background</p> <p>To determine whether resveratrol, a natural plant-derived drug, has protective effects against antibody-induced apoptosis of retinal cells <it>in vitro </it>and to provide insights on the mechanism of resveratrol protection.</p> <p>Findings</p> <p>E1A.NR3 retinal cells pretreated with 40 μM resveratrol were grown in the presence of anti-recoverin (Rec-1), anti-enolase (Enol-1) antibodies, and normal purified immunoglobulins. When the cells were exposed to resveratrol before treatment with Enol-1 or Rec-1 antibodies, 30–55% more cells survived compared to the resveratrol-untreated cells. Western blotting showed a reduction in proapoptotic protein Bax in the cytoplasm and mitochondria of resveratrol-treated cells. Resveratrol-pretreated cells also showed a significant decrease in intracellular calcium and an inhibition of caspase-3 activity as compared to the untreated cells. Sirt1 expression was greatly reduced in the cells grown in the presence of Rec-1 and Enol-1, but it increased about five times in the resveratrol-pretreated cells. Immunocytochemistry revealed that Sirt1 expression in the cytoplasm and nucleus was colocalized with Ku70 expression in resveratrol-treated cells, suggesting possible interaction with each other in the cell. The pattern of the Ku70 cellular localization also overlapped with the Bax cellular localization in treated and untreated cells.</p> <p>Conclusion</p> <p><it>In vitro </it>protection of retinal cells from apoptosis by resveratrol occurred through multiple early molecular events, such as reduction of intracellular calcium levels, down-regulation of Bax, up-regulation of Sirt1 and Ku70 activities, and inhibition of caspase-3 activity. These findings will help designing future <it>in vivo </it>and pre-clinical treatments for autoimmune retinopathies.</p

A translational continuum of model systems for evaluating treatment strategies in Alzheimer’s disease: isradipine as a candidate drug

A growing body of evidence supports the ‘calcium hypothesis’ of Alzheimer’s disease (AD), which postulates that a variety of insults might disrupt the homeostatic regulation of neuronal calcium (Ca2+) in the brain, resulting in the progressive symptoms that typify the disease. However, despite ongoing efforts to develop new methods for testing therapeutic compounds that might be beneficial in AD, no single bioassay permits both rapid screening and in vivo validation of candidate drugs that target specific components of the Ca2+ regulatory machinery. To address this issue, we have integrated four distinct model systems that provide complementary information about a trial compound: the human neuroblastoma MC65 line, which provides an in vitro model of amyloid toxicity; a transgenic Drosophila model, which develops age-dependent pathologies associated with AD; the 3×TgAD transgenic mouse, which recapitulates many of the neuropathological features that typify AD; and the embryonic nervous system of Manduca, which provides a novel in vivo assay for the acute effects of amyloid peptides on neuronal motility. To demonstrate the value of this ‘translational suite’ of bioassays, we focused on a set of clinically approved dihydropyridines (DHPs), a class of well-defined inhibitors of L-type calcium channels that have been suggested to be neuroprotective in AD. Among the DHPs tested in this study, we found that isradipine reduced the neurotoxic consequences of β-amyloid accumulation in all four model systems without inducing deleterious side effects. Our results provide new evidence in support of the Ca2+ hypothesis of AD, and indicate that isradipine represents a promising drug for translation into clinical trials. In addition, these studies also demonstrate that this continuum of bioassays (representing different levels of complexity) provides an effective means of evaluating other candidate compounds that target specific components of the Ca2+ regulatory machinery and that therefore might be beneficial in the treatment of AD