Ubiquitination of Mitochondrial Proteins in Alzheimer's Disease

PROJECT SUMMARY/ABSTRACT Extensive studies have observed impaired mitochondria in patients and animal models of Alzheimer’s disease (AD). Specifically, a large body of research has made the connection between altered mitochondria functions and accumulation of amyloid-β (Aβ) peptides in various experimental systems. However, given the complex

functions of mitochondria and Aβ, further research remains overwhelmingly needed to better understand mitochondrial dysfunction in AD in order to reveal promising therapeutic targets. To approach this question, we have collected a large amount of preliminary data to show that a E3 ubiquitin ligase, named neural precursor

cell-expressed developmentally down-regulated gene 4-like (Nedd4L), is associated with mitochondria and regulates mitochondrial membrane potential. We further showed that Nedd4L is dephosphorylated in a familial AD mouse model, APP/PS1 mice, and dephosphorylated Nedd4L ubiquitinates a mitochondrial outer membrane

protein mitofusion-2 (MFN2). Previous studies have observed downregulation of MFN2 in post-mortem patient samples and animal models of AD and suggest a contribution of MFN2 downregulation in AD pathogenesis. Based on these data and prior research, we hypothesize that dephosphorylation of Nedd4L in APP/PS1 mice

contributes to impaired mitochondrial function and neurodegeneration in part through ubiquitinating MFN2. We will test this hypothesis with two aims. Aim 1 will employ multiple unique mouse models to determine how the two major isoforms of Nedd4L differentially regulate mitochondrial functions and how dephosphorylation of

Nedd4L affects those functions. Aim 2 will employ a cell-permeable peptide to promote phosphorylation of endogenous Nedd4L in vivo to assess the impacts of Nedd4L dephosphorylation on neuronal functions and health in APP/PS1 mice. Our goals are to establish Nedd4L as an upstream regulator contributing to the

dysfunctions of MFN2 and mitochondria in APP/PS1 mice and to introduce approaches that can rectify or ameliorate the impairment.