title: Proteomic and functional alterations in brain mitochondria from Tg2576 mice occur before amyloid plaque deposition.
abstract: Synaptic dysfunction is an early event in Alzheimer's disease patients and has also been detected in transgenic mouse models. In the present study, we analyzed proteomic changes in synaptosomal fractions from Tg2576 mice that overexpress mutant human amyloid precursor protein (K670N, M671L) and from their nontransgenic littermates. Cortical and hippocampal tissue was microdissected at the onset of cognitive impairment, but before deposition of amyloid plaques. Crude synaptosomal fractions were prepared by differential centrifugation, proteins were separated by 2-D DIGE and identified by MS/MS. Significant alterations were detected in mitochondrial heat shock protein 70 pointing to a mitochondrial stress response. Subsequently, synaptosomal versus nonsynaptic mitochondria were purified from Tg2576 mice brains by density gradient centrifugation. Mitochondrial proteins were separated by IEF or Blue-native gel electrophoresis in the first dimension and SDS-PAGE in the second dimension. Numerous changes in the protein subunit composition of the respiratory chain complexes I and III were identified. Levels of corresponding mRNAs remain unchanged as shown by Affymetrix oligonucleotide array analysis. Functional examination revealed impaired state 3 respiration and uncoupled respiration in brain mitochondria from young Tg2576 mice. By immunoblotting, amyloid-beta oligomers were detected in synaptosomal fractions from Tg2576 mice and reduced glucose metabolism was observed in Tg2576 mice brains by [14C]-2-deoxyglucose infusion. Taken together, we demonstrate alterations in the mitochondrial proteome and function that occur in Tg2576 mice brains before amyloid plaque deposition suggesting that mitochondria are early targets of amyloid-beta aggregates.
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Gillardon
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rist
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Kussmaul
authors.affiliation: University of Zurich, Zurich, Switzerland.
authors.forename: Johannes
authors.initials: J
authors.lastname: Vogel
authors.affiliation: GE Healthcare, Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Berg
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Danzer
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Kraut
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Hengerer
mesh_terms: D000682:Amyloid / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002250:Carbon Radioisotopes / Q000737:chemistry; D005947:Glucose / Q000378:metabolism; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D000682:Amyloid; D016564:Amyloid beta-Protein Precursor; D002250:Carbon Radioisotopes; D020543:Proteome; D005947:Glucose