Histopathological and Neurological Features of Atg4b Knockout Mice

This investigation found that genetic inactivation of mouse Atg4b, 1 of the 4 mammalian homologs of the autophagy-related gene Atg4, resulted in amorphous globular bodies in the neuropil of the deep cerebellar nuclei and adjacent vestibular nuclei but nowhere else in the brain or other tissues. The spheroid-like bodies in the deep cerebellar and vestibular nuclei showed heterogeneous composition, reactivity with anti-ubiquitin antibody, and staining characteristics of proteinaceous material. Atg4b-deficient (Atg4b(-/-) ) mice also showed a mild but measurable impairment of motor performance on the Rotarod. Atg4b(-/-) mice produced by breeding heterozygous parents were produced at a slightly lower than expected ratio to heterozygous and wild-type siblings but showed no other clear abnormalities in a battery of screening tests. These findings appear to be different than those reported for inactivation of other Atg4 homologs, suggesting that these homologs have tissue-specific functions beyond redundancy.