title: Abnormalities in synaptic dynamics during development in a mouse model of spinocerebellar ataxia type 1.
abstract: Late-onset neurodegenerative diseases are characterized by neurological symptoms and progressive neuronal death. Accumulating evidence suggests that neuronal dysfunction, rather than neuronal death, causes the symptoms of neurodegenerative diseases. However, the mechanisms underlying the dysfunction that occurs prior to cell death remain unclear. To investigate the synaptic basis of this dysfunction, we employed in vivo two-photon imaging to analyse excitatory postsynaptic dendritic protrusions. We used Sca1(154Q/2Q) mice, an established knock-in mouse model of the polyglutamine disease spinocerebellar ataxia type 1 (SCA1), which replicates human SCA1 features including ataxia, cognitive impairment, and neuronal death. We found that Sca1(154Q/2Q) mice exhibited greater synaptic instability than controls, without synaptic loss, in the cerebral cortex, where obvious neuronal death is not observed, even before the onset of distinct symptoms. Interestingly, this abnormal synaptic instability was evident in Sca1(154Q/2Q) mice from the synaptic developmental stage, and persisted into adulthood. Expression of synaptic scaffolding proteins was also lower in Sca1(154Q/2Q) mice than controls before synaptic maturation. As symptoms progressed, synaptic loss became evident. These results indicate that aberrant synaptic instability, accompanied by decreased expression of scaffolding proteins during synaptic development, is a very early pathology that precedes distinct neurological symptoms and neuronal cell death in SCA1.
authors.affiliation: Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan.|CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hatanaka
authors.affiliation: Center for Brain Integration Research, Tokyo Medical &Dental University, 1-5-45 Yushima, Bunkyo, Tokyo 113-8510, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Watase
authors.affiliation: Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan.|CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Wada
authors.affiliation: Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan.|CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nagai
mesh_terms: D000818:Animals; D000067696:Ataxin-1 / Q000235:genetics* / Q000378:metabolism; D056547:CA1 Region, Hippocampal / Q000378:metabolism / Q000473:pathology; D002540:Cerebral Cortex / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D055879:Gene Knock-In Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D036641:Microscopy, Fluorescence, Multiphoton; D009687:Nuclear Proteins / Q000378:metabolism; D020754:Spinocerebellar Ataxias / Q000378:metabolism / Q000473:pathology*; D013569:Synapses / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000067696:Ataxin-1; C000593750:Atxn1 protein, mouse; D009687:Nuclear Proteins