Beta-amyloid peptide toxicity in organotypic hippocampal slice culture involves Akt/PKB, GSK-3beta, and PTEN.
In the present study we investigated the toxicity induced by exposing organotypic slice culture to beta-amyloid peptide 25-35 (25microM) for 1, 3, 6, 12, 24 and 48h. To elucidate a mechanism involved in its toxicity, we studied the PI3-K cell signaling pathway, particularly Akt/PKB, GSK-3beta, and PTEN proteins. Cell death was quantified by propidium iodide uptake and proteins were analyzed by immunoblotting. Our results showed a significant cell death after 48h of beta-amyloid 25-35 peptide exposition. The exposition of cultures to beta-amyloid peptide resulted in an increase in the phosphorylation state of Akt and GSK-3beta proteins after 6h, followed by a decrease of the phosphorylation state of these proteins after 12h of exposition. However, after 24h of peptide treatment, the phosphorylation of GSK-3beta presented a new increase while the phosphorylation of Akt remained down. The immunocontent of the PTEN protein, an indirect Akt phosphatase, increased after 24 and 48h of beta-amyloid exposition. These results suggest an involvement of Akt dephosphorylation/inactivation in the toxicity induced by the beta-amyloid 25-35 peptide in organotypic slice hippocampal culture, probably induced by increasing PTEN immunocontent. Taken together, our results provide more information about the molecular mechanisms involved on beta-amyloid peptide toxicity.
Nassif
Melissa
M
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, 90035-003 Porto Alegre, RS, Brazil.
Hoppe
Juliana
J
Santin
Katiane
K
Frozza
Rudimar
R
Zamin
Lauren L
LL
Simão
Fabrício
F
Horn
Ana P
AP
Salbego
Christianne
C
D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D015153:Blotting, Western; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006624:Hippocampus / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats
D016229:Amyloid beta-Peptides; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D051059:PTEN Phosphohydrolase; C487216:Pten protein, rat