title: Overexpression of Swedish mutant APP in aged astrocytes attenuates excitatory synaptic transmission.
abstract: Amyloid precursor protein (APP), a type I transmembrane protein, has different aspects, namely, performs essential physiological functions and produces β-amyloid peptide (Aβ). Overexpression of neuronal APP is responsible for synaptic dysfunction. In the central nervous system, astrocytes - a major glial cell type - have an important role in the regulation of synaptic transmission. Although APP is expressed in astrocytes, it remains unclear whether astrocytic overexpression of mutant APP affects synaptic transmission. In this study, the effect of astrocytic overexpression of a mutant APP on the excitatory synaptic transmission was investigated using coculture system of the transgenic (Tg) cortical astrocytes that express the human APP695 polypeptide with the double mutation K670N + M671L found in a large Swedish family with early onset Alzheimer's disease, and wild-type hippocampal neuron. Significant secretion of Aβ 1-40 and 1-42 was observed in cultured cortical astrocytes from the Tg2576 transgenic mouse that genetically overexpresses Swedish mutant APP. Under the condition, Tg astrocytes did not affect excitatory synaptic transmission of cocultured wild-type neurons. However, aged Tg astrocytes cultured for 9 weeks elicited a significant decrease in excitatory synaptic transmission in cocultured neurons. Moreover, a reduction in the number of readily releasable synaptic vesicles accompanied a decrease in the number of excitatory synapses in neurons cocultured with aged Tg astrocytes. These observations indicate that astrocytic expression of the mutant APP is involved in the downregulation of synaptic transmission with age.
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan shutarok@fukuoka-u.ac.jp.
authors.forename: Shutaro
authors.initials: S
authors.lastname: Katsurabayashi
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawano
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Ii
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Nakano
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Tatsumi
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan A.I.G. Collaborative Research Institute for Aging and Brain Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Kubota
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Takasaki
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan A.I.G. Collaborative Research Institute for Aging and Brain Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Mishima
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Fujiwara
authors.affiliation: Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan A.I.G. Collaborative Research Institute for Aging and Brain Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Iwasaki
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000502:physiology*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D008822:Mice, Transgenic; D009154:Mutation / Q000502:physiology*; D013548:Sweden; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D016564:Amyloid beta-Protein Precursor
keywords: Aging; alzheimer's disease; amyloid; astrocyte; synaptic release