Selective autophagic clearance of protein aggregates is mediated by the autophagy receptor, TAX1BP1

Abstract

Abstract Misfolded protein aggregates can disrupt cellular homeostasis and cause toxicity, a hallmark of numerous neurodegenerative diseases. Protein quality control by the ubiquitin proteasome system (UPS) and autophagy is vital for clearance of aggregates and maintenance of cellular homeostasis 1 . Autophagy receptor proteins bridge the interaction between ubiquitinated proteins and the autophagy machinery allowing selective elimination of cargo 2 . Aggrephagy is critical to protein quality control, but how aggregates are recognized and targeted for degradation is not well understood. Here we examine the requirements for 5 autophagy receptor proteins: OPTN, NBR1, p62, NDP52, and TAX1BP1 in proteotoxic stress-induced aggregate clearance. Endogenous TAX1BP1 is both recruited to and required for the clearance of stress-induced aggregates while overexpression of TAX1BP1 increases aggregate clearance through autophagy. Furthermore, TAX1BP1 depletion sensitizes cells to proteotoxic stress and Huntington’s disease-linked polyQ proteins, whereas TAX1BP1 overexpression clears cells of polyQ protein aggregates by autophagy. We propose a broad role for TAX1BP1 in the clearance of cytotoxic proteins, thus identifying a new mode of clearance of protein inclusions.