Caspase cleaved presenilin-1 is part of active gamma-secretase complexes.
gamma-Secretase is a key enzyme involved in the processing of the beta-amyloid precursor protein into amyloid beta-peptides (Abeta). Abeta accumulates and forms plaques in Alzheimer's disease (AD) brains. A progressive neurodegeneration and cognitive decline occurs during the course of the disease, and Abeta is believed to be central for the molecular pathogenesis of AD. Apoptosis has been implicated as one of the mechanisms behind the neuronal cell loss seen in AD. We have studied preservation and activity of the gamma-secretase complex during apoptosis in neuroblastoma cells (SH-SY5Y) exposed to staurosporine (STS). We report that the known components (presenilin, Nicastrin, Aph-1 and Pen-2) interact and form active gamma-secretase complexes in apoptotic cells. In addition, the fragments corresponding to the PS1 N-terminal fragment and the caspase-cleaved PS1 C-terminal fragment (PS1-caspCTF) were found to form active gamma-secretase complexes when co-expressed in presenilin (PS) knockout cells. Interestingly, PS1-caspCTF replaced the normal PS1 C-terminal fragment and was co-immunoprecipitated with the gamma-secretase complex in SH-SY5Y cells exposed to STS. In addition, Abeta was detected in medium from apoptotic HEK APP(swe) cells. Together, the data show that gamma-secretase complexes containing PS1-caspCTF are active, and suggest that this proteolytic activity is also important in dying cells and may affect the progression of AD.
Karolinska Institutet, Neurotec, Section for Experimental Geriatrics, Huddinge, Sweden.
Camilla A
CA
Hansson
Bogdan O
BO
Popescu
Hanna
H
Laudon
Angel
A
Cedazo-Minguez
Laurentiu M
LM
Popescu
Bengt
B
Winblad
Maria
M
Ankarcrona
D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western / Q000379:methods; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D008156:Luciferases / Q000096:biosynthesis; D008565:Membrane Proteins / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D009154:Mutation; D009447:Neuroblastoma; D010446:Peptide Fragments; D053764:Presenilin-1; D017434:Protein Structure, Tertiary; D019311:Staurosporine / Q000494:pharmacology; D013347:Subcellular Fractions / Q000187:drug effects; D013778:Tetrazolium Salts; D013844:Thiazoles; D014162:Transfection / Q000379:methods
D016564:Amyloid beta-Protein Precursor; D002843:Chromatin; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D046912:Multiprotein Complexes; C508853:PSEN1 protein, human; D010446:Peptide Fragments; D053764:Presenilin-1; D013778:Tetrazolium Salts; D013844:Thiazoles; D008156:Luciferases; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D020169:Caspases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; C022616:thiazolyl blue; D019311:Staurosporine