title: Loss of autophagy in the central nervous system causes neurodegeneration in mice.
abstract: Protein quality-control, especially the removal of proteins with aberrant structures, has an important role in maintaining the homeostasis of non-dividing neural cells. In addition to the ubiquitin-proteasome system, emerging evidence points to the importance of autophagy--the bulk protein degradation pathway involved in starvation-induced and constitutive protein turnover--in the protein quality-control process. However, little is known about the precise roles of autophagy in neurons. Here we report that loss of Atg7 (autophagy-related 7), a gene essential for autophagy, leads to neurodegeneration. We found that mice lacking Atg7 specifically in the central nervous system showed behavioural defects, including abnormal limb-clasping reflexes and a reduction in coordinated movement, and died within 28 weeks of birth. Atg7 deficiency caused massive neuronal loss in the cerebral and cerebellar cortices. Notably, polyubiquitinated proteins accumulated in autophagy-deficient neurons as inclusion bodies, which increased in size and number with ageing. There was, however, no obvious alteration in proteasome function. Our results indicate that autophagy is essential for the survival of neural cells, and that impairment of autophagy is implicated in the pathogenesis of neurodegenerative disorders involving ubiquitin-containing inclusion bodies.
authors.affiliation: Laboratory of Frontier Science, Tokyo Metropolitan Institute of Medical Science, Bunkyo-ku, Tokyo 113-8613, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Komatsu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Waguri
authors.forename: Tomoki
authors.initials: T
authors.lastname: Chiba
authors.forename: Shigeo
authors.initials: S
authors.lastname: Murata
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Iwata
authors.forename: Isei
authors.initials: I
authors.lastname: Tanida
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueno
authors.forename: Masato
authors.initials: M
authors.lastname: Koike
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Uchiyama
authors.forename: Eiki
authors.initials: E
authors.lastname: Kominami
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D000071193:Autophagy-Related Protein 7; D016923:Cell Death; D002490:Central Nervous System / Q000473:pathology* / Q000503:physiopathology*; D002531:Cerebellum / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology; D002479:Inclusion Bodies / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics; D064231:Nestin; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D015996:Survival Rate; D025801:Ubiquitin / Q000378:metabolism
chemical_list: C502661:Atg7 protein, mouse; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D000071193:Autophagy-Related Protein 7