title: The gamma secretase-generated carboxyl-terminal domain of the amyloid precursor protein induces apoptosis via Tip60 in H4 cells.
abstract: The amyloid precursor protein (APP), a large glycoprotein highly expressed in neurons, is cleaved in its intramembranous domain by gamma secretase to generate amyloid-beta and a free carboxyl-terminal intracellular fragment (APP-CT), which has previously been suggested to interact with the adapter protein Fe65 and the histone acetyltransferase Tip60. An identical gamma secretase activity mediates cleavage of Notch, releasing an intracellular signaling domain that translocates to the nucleus. We examined the effect of an ectopically expressed 58-amino acid APP-CT fragment (APP-C58) on human H4 neuroglioma cells. We demonstrate by confocal microscopy and fluorescence resonance energy transfer analysis that APP-C58 translocates to the nucleus and forms a complex in the nucleus with the Tip60, independent of interactions with Fe65. APP-C58 transfected H4 cells undergo apoptosis within 48-72 h, marked by nuclear blebbing, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining, and blockade by a caspase inhibitor. When nuclear access of APP-C58 is prevented by fusing with a strong membrane-targeting farnesylation domain, apoptosis is blocked. APP-C58-induced apoptosis was markedly enhanced by co-transfection with wild type Tip60 and decreased by mutant Tip60 lacking histone acetyltransferase activity, suggesting that Tip60 mediates APP-CT-induced cell death. Thus, gamma secretase cleavage of APP may contribute to Alzheimer's disease-related neurodegeneration in two ways: release of amyloid-beta and liberation of a bioactive carboxyl-terminal domain from membrane-bound APP.
authors.affiliation: Alzheimer's Disease Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
authors.forename: Ayae
authors.initials: A
authors.lastname: Kinoshita
authors.forename: Christa M
authors.initials: CM
authors.lastname: Whelan
authors.forename: Oksana
authors.initials: O
authors.lastname: Berezovska
authors.forename: Bradley T
authors.initials: BT
authors.lastname: Hyman
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry* / Q000378:metabolism; D000544:Alzheimer Disease; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D016282:Aspartic Acid Endopeptidases; D002467:Cell Nucleus / Q000378:metabolism; D019281:Dimerization; D010450:Endopeptidases / Q000378:metabolism*; D004735:Energy Transfer; D005822:Genetic Vectors; D051548:Histone Acetyltransferases; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D000074443:Lysine Acetyltransferase 5; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D016564:Amyloid beta-Protein Precursor; D007770:L-Lactate Dehydrogenase; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C098489:KAT5 protein, human; D000074443:Lysine Acetyltransferase 5; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human