Neuroprotection by c-Jun NH2-terminal kinase inhibitor SP600125 against potassium deprivation-induced apoptosis involves the Akt pathway and inhibition of cell cycle reentry.
Increasing evidence implicates the c-Jun NH(2)-terminal kinase (JNK) pathway in the regulation of apoptosis in neurodegenerative diseases. In this study, we examined the neuroprotective effect of SP600125, a selective JNK inhibitor, in cerebellar granule cells (CGNs) deprived of serum and potassium (S/K withdrawal). S/K withdrawal-induced apoptosis occurs via activation of multiple pro-apoptotic pathways, including re-entry into the cell cycle, activation of glycogen synthase kinase-3 beta (GSK-3beta), cyclin-dependent kinase 5 (cdk5/p35) breakdown, formation of cdk5/p25 and JNK activation. Here we demonstrate that SP600125 is able to inhibit all these pro-apoptotic pathways via the inhibition of JNK. Further, we found that JNK inhibition maintains the phosphorylation/activation of Akt after S/K withdrawal. For further confirmation of this result, we studied several targets downstream of Akt including GSK-3beta, p-FOXO1, p-CREB and p35. In addition, the specific PI3K/Akt inhibitor LY294002 greatly diminished the antiapoptotic effects of SP600125 upon S/K withdrawal, confirming that Akt is involved in the neuroprotection achieved by SP600125. These results suggest that the maintenance of the PI3-kinase/Akt pathway by inhibition of JNK contributes to the prevention of apoptosis in rat cerebellar granule neurons mediated by S/K withdrawal. Furthermore, we propose that JNK may regulate the cell cycle re-entry by a novel mechanism that involves Akt, GSK-3beta and Rb phosphorylation.
Yeste-Velasco
M
M
Facultat de Farmàcia, Institut de Biomedicina, Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Universitat de Barcelona, Nucli Universitari de Pedralbes, 08028 Barcelona, Spain.
Folch
J
J
Casadesús
G
G
Smith
M A
MA
Pallàs
M
M
Camins
A
A
D000818:Animals; D000873:Anthracenes / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002453:Cell Cycle / Q000187:drug effects*; D002478:Cells, Cultured; D002531:Cerebellum / Q000187:drug effects / Q000502:physiology; D002867:Chromones / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051858:Forkhead Transcription Factors / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009025:Morpholines / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D010770:Phosphotransferases / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D000071161:Forkhead Box Protein O1
D000873:Anthracenes; D002867:Chromones; D017362:Cyclic AMP Response Element-Binding Protein; D051360:Cyclin-Dependent Kinase 5; D004791:Enzyme Inhibitors; D051858:Forkhead Transcription Factors; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D048031:JNK Mitogen-Activated Protein Kinases; D009025:Morpholines; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D010770:Phosphotransferases; D011188:Potassium; D051057:Proto-Oncogene Proteins c-akt; C492235:Cdk5r1 protein, rat; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1; C432165:pyrazolanthrone; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C000605508:Gsk3b protein, rat