title: Signal transduction through tyrosine-phosphorylated C-terminal fragments of amyloid precursor protein via an enhanced interaction with Shc/Grb2 adaptor proteins in reactive astrocytes of Alzheimer's disease brain.
abstract: The proteolytic processing of amyloid precursor protein (APP) through the formation of membrane-bound C-terminal fragments (CTFs) and of soluble beta-amyloid peptides likely influences the development of Alzheimer's disease (AD). We show that in human brain a subset of CTFs are tyrosine-phosphorylated and form stable complexes with the adaptor protein ShcA. Grb2 is also part of these complexes, which are present in higher amounts in AD than in control brains. ShcA immunoreactivity is also greatly enhanced in patients with AD and occurs at reactive astrocytes surrounding cerebral vessels and amyloid plaques. A higher amount of phospho-ERK1,2, likely as result of the ShcA activation, is present in AD brains. In vitro experiments show that the ShcA-CTFs interaction is strictly confined to glial cells when treated with thrombin, which is a well known ShcA and ERK1,2 activator and a regulator of APP cleavage. In untreated cells ShcA does not interact with either APP or CTFs, although they are normally generated. Altogether these data suggest that CTFs are implicated in cell signaling via Shc transduction machinery, likely influencing MAPK activity and glial reaction in AD patients.
authors.affiliation: Sezione di Farmacologia, Dipartimento di Oncologia Biologia e Genetica, Università di Genova, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Russo
authors.forename: Virginia
authors.initials: V
authors.lastname: Dolcini
authors.forename: Serena
authors.initials: S
authors.lastname: Salis
authors.forename: Valentina
authors.initials: V
authors.lastname: Venezia
authors.forename: Nicola
authors.initials: N
authors.lastname: Zambrano
authors.forename: Tommaso
authors.initials: T
authors.lastname: Russo
authors.forename: Gennaro
authors.initials: G
authors.lastname: Schettini
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D004789:Enzyme Activation; D051380:GRB2 Adaptor Protein; D006801:Humans; D007150:Immunohistochemistry; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D013917:Thrombin / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016564:Amyloid beta-Protein Precursor; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C495950:Grb2 protein, rat; D011506:Proteins; D014443:Tyrosine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D013917:Thrombin