The C-terminal domain of the heavy chain of tetanus toxin rescues cerebellar granule neurones from apoptotic death: involvement of phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways.
When cultured cerebellar granule neurones are transferred from a medium containing high extracellular potassium concentration ([K+]e) (25 mm) to one with lower [K+]e (5 mm), caspase-3 activity is induced and cells die apoptotically. In contrast, if cells in non-depolarizing conditions are treated with brain-derived neurotrophic factor (BDNF), caspase-3 activity, chromatin condensation and cell death are markedly diminished. In this study, we show that the C-terminal domain of the tetanus toxin heavy-chain (Hc-TeTx) is able to produce the same neuroprotective effect, as assessed by reduction of tetrazolium salts and by chromatin condensation. Hc-TeTx-conferred neuroprotection appears to depend on phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase kinase, as is demonstrated by the selective inhibitors Wortmannin and PD98059, respectively. Hc-TeTx also induces phosphorylation of the tyrosine kinase BDNF receptor, activation of p21Ras in its GTP-bound form, and phosphorylation of the cascade including extracellular-signal-regulated kinases-1/2 (ERK-1/2), p90 ribosomal S6 kinase (p90rsk) and CREB (cAMP-response-element-binding protein). On the other hand, activation of the Akt pathway is also detected, as well as inhibition of the active form of caspase-3. These results point to an implication of both PI3K- and ERK-dependent pathways in the promotion of cerebellar granule cell survival by Hc-TeTx.
Departament de Bioquímica i de Biologia Molecular and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Imane
I
Chaïb-Oukadour
Carles
C
Gil
José
J
Aguilera
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007211:Indoles; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011188:Potassium / Q000633:toxicity; D011233:Precipitin Tests / Q000379:methods; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D013744:Tetanus Toxin / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D000077191:Wortmannin
D000730:Androstadienes; D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007211:Indoles; D010446:Peptide Fragments; D013744:Tetanus Toxin; D013778:Tetrazolium Salts; D013844:Thiazoles; C040635:tetanus toxin fragment C; C007293:DAPI; D019869:Phosphatidylinositol 3-Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; C022616:thiazolyl blue; D011188:Potassium; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin