MITOCHONDRIAL DYSFUNCTION IN NNAD MUTANT FLIES AND PURKINJE CELL DEGENERATION

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Purkinje cell degeneration (pcd) mouse is a recessive model of neurodegeneration, involving cerebellum and retina. Purkinje cell death in pcd is dramatic, as >99% of Purkinje neurons are lost in three weeks. Loss-of-function of Nna1 causes pcd, and Nna1 is a highly conserved zinc carboxypeptidase. To determine the basis of pcd, we implemented a two pronged approach, combining characterization of loss-of-function phenotypes of the Drosophila Nna1 orthologue (NnaD) with proteomics analysis of pcd mice. Reduced NnaD function yielded larval lethality, with survivors displaying phenotypes that mirror disease in pcd. Quantitative proteomics revealed expression alterations for glycolytic and oxidative phosphorylation enzymes. Nna proteins localize to mitochondria, loss of NnaD / Nna1 produces mitochondrial abnormalities, and pcd mice display altered proteolytic processing of Nna1 interacting proteins. Our studies indicate that Nna1 loss-of-function results in altered bioenergetics and mitochondrial dysfunction, and suggest that pcd shares pathogenic features with neurodegenerative disorders such as Parkinson's disease.