Neuroprotective effects of caffeine against complex I inhibition-induced apoptosis are mediated by inhibition of the Atm/p53/E2F-1 path in cerebellar granule neurons.
The aim of the present study was to evaluate the neuroprotective effects of caffeine, an inhibitor of ataxia telangiectasia mutated (ATM) enzyme and an antagonist of adenosine receptors, in two models of apoptosis in cerebellar granule neurons (CGNs): the inhibition of mitochondrial complex I by the neurotoxin MPP(+) and serum and potassium deprivation. We used cerebellar granule neurons because of low glial contamination. Cell viability was measured by the MTT method, and apoptosis was evaluated by assessing DNA fragmentation with flow cytometry or quantification of nuclear condensation. Our data indicate that the neuroprotective effects of caffeine in the MPP+ model of apoptosis are mediated through activation of the ATM/p53 pathway. In addition, caffeine decreased the expression of cyclin D and the transcription factor E2F-1, a regulator of apoptosis in neurons. Caffeine-mediated neuroprotection was not mediated through blockade of adenosine receptors because DPCPX and CGS-15943, two antagonists of these receptors, failed to attenuate apoptosis produced by MPP+ treatment. In addition, caffeine did not exert neuroprotective effects after serum and potassium withdrawal, a p53-independent model of apoptosis. Taken together, our findings indicate that DNA damage/ATM activation is a key component of MPP+-induced apoptosis in CGNs through activation of p53 and reentry into the cell cycle, specifically expression of the transcription factor E2F-1.
Alvira
Daniel
D
Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Universitat de Barcelona, Nucli Universitari de Pedralbes, Barcelona, Spain.
Yeste-Velasco
Marc
M
Folch
Jaume
J
Casadesús
Gemma
G
Smith
Mark A
MA
Pallàs
Mercè
M
Camins
Antoni
A
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D050687:E2F1 Transcription Factor / Q000378:metabolism; D042967:Electron Transport Complex I / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry / Q000379:methods; D009433:Neural Inhibition / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050687:E2F1 Transcription Factor; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D002110:Caffeine; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D042967:Electron Transport Complex I