Open AccessOverexpression of Swedish mutant APP in aged astrocytes attenuates excitatory synaptic transmission
Author(s) -
Katsurabayashi Shutaro,
Kawano Hiroyuki,
Ii Miyuki,
Nakano Sachiko,
Tatsumi Chihiro,
Kubota Kaori,
Takasaki Kotaro,
Mishima Kenichi,
Fujiwara Michihiro,
Iwasaki Katsunori
Publication year - 2016
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12665
Subject(s) - neurotransmission , excitatory postsynaptic potential , amyloid precursor protein , astrocyte , biology , neuroscience , synaptic fatigue , synaptic plasticity , microbiology and biotechnology , hippocampal formation , neuron , synaptic vesicle , inhibitory postsynaptic potential , alzheimer's disease , central nervous system , medicine , biochemistry , receptor , vesicle , disease , membrane
Amyloid precursor protein ( APP ), a type I transmembrane protein, has different aspects, namely, performs essential physiological functions and produces β ‐amyloid peptide (A β ). 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 APP 695 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 A β 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.