Preventing Ataxin-3 protein cleavage mitigates degeneration in a Drosophila model of SCA3.
Protein cleavage is a common feature in human neurodegenerative disease. Ataxin-3 protein with an expanded polyglutamine (polyQ) repeat causes spinocerebellar ataxia type-3 (SCA3), also called Machado-Joseph disease, and is cleaved in mammalian cells, transgenic mice and SCA3 patient brain tissue. However, the pathological significance of Ataxin-3 cleavage has not been carefully examined. To gain insight into the significance of Ataxin-3 cleavage, we developed a Drosophila SL2 cell-based model as well as transgenic fly models. Our data indicate that Ataxin-3 protein cleavage is conserved in the fly and may be caspase-dependent as reported previously. Importantly, comparison of flies expressing either wild-type or caspase-site mutant proteins indicates that Ataxin-3 cleavage enhances neuronal loss in vivo. This genetic in vivo confirmation of the pathological role of Ataxin-3 cleavage indicates that therapies targeting Ataxin-3 cleavage might slow disease progression in SCA3 patients.
Jung
Joonil
J
Department of Biology and University of Pennsylvania, Philadelphila, PA 19104-6018, USA.
Xu
Kexiang
K
Lessing
Derek
D
Bonini
Nancy M
NM
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D000067699:Ataxin-3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004195:Disease Models, Animal; D004331:Drosophila melanogaster / Q000235:genetics; D006801:Humans; D017827:Machado-Joseph Disease / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C092341:ATXN3 protein, human; D000067699:Ataxin-3; D020169:Caspases