A role for the autophagy receptor NBR1 in the degradation of tau aggregates

Abstract

Neurofibrillary tangles (NFTs), comprising hyperphosphorylated and aggregated Tau protein, are a primary neuropathological feature of Alzheimer's Disease (AD). In patients, the formation and spread of NFTs across the brain correlate with cognitive decline. However, the mechanisms driving Tau aggregation and leading to the subsequent neuronal dysfunction are not fully understood. In this study, we explored proteomic and phosphoproteomic changes resulting from the seed-induced aggregation of endogenous Tau in human neurons, derived from induced pluripotent stem cells (iPSCs). We discovered previously undescribed phosphorylation sites on NBR1, an autophagy receptor, which were significantly altered by Tau aggregation in vitro. We further show that NBR1 directly interacts with phosphorylated Tau and Tau aggregates in various cellular models. This interaction is associated with autophagic Tau degradation in HEK biosensor cells, and siRNA-mediated knockdown of NBR1 significantly increases Tau aggregate levels in iPSC-derived neurons. Additionally, we find that NBR1 expression is significantly increased in AD patients, and it specifically interacts with Tau in human AD brain, underscoring the relevance of our findings to the human disease. These insights provide a deeper understanding of the molecular interactions between autophagy receptors and Tau pathology in AD and reveal a role for NBR1 as an important receptor for pathological forms of Tau.

Keywords: Alzheimer's disease; Autophagy receptor; Mass spectrometry; Phosphoproteomics; Proteomics; Tau aggregation; iPSC-derived neurons.