UXT chaperone prevents proteotoxicity by acting as an autophagy adaptor for p62-dependent aggrephagy

Min Ji Yoon,Jiyeon Ohk,Hosung Jung,Eun Jin Kim,Hyun Kyu Song,Jinyoung Lee,Eui-Ju Choi,Chungho Kim,Yoon Ki Kim,Jae-Sung Woo,Yeon-Gil Choi,Chansik Yang,Boyoon Choi,Chanhee Kang,Yongcheol Cho

doi:10.1038/s41467-021-22252-7

Min Ji Yoon, Jiyeon Ohk + Show 13 more

Open Access

https://doi.org/10.1038/s41467-021-22252-7

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Abstract

p62/SQSTM1 is known to act as a key mediator in the selective autophagy of protein aggregates, or aggrephagy, by steering ubiquitinated protein aggregates towards the autophagy pathway. Here, we use a yeast two-hybrid screen to identify the prefoldin-like chaperone UXT as an interacting protein of p62. We show that UXT can bind to protein aggregates as well as the LB domain of p62, and, possibly by forming an oligomer, increase p62 clustering for its efficient targeting to protein aggregates, thereby promoting the formation of the p62 body and clearance of its cargo via autophagy. We also find that ectopic expression of human UXT delays SOD1(A4V)-induced degeneration of motor neurons in a Xenopus model system, and that specific disruption of the interaction between UXT and p62 suppresses UXT-mediated protection. Together, these results indicate that UXT functions as an autophagy adaptor of p62-dependent aggrephagy. Furthermore, our study illustrates a cooperative relationship between molecular chaperones and the aggrephagy machinery that efficiently removes misfolded protein aggregates.

Highlights

P62/SQSTM1 is known to act as a key mediator in the selective autophagy of protein aggregates, or aggrephagy, by steering ubiquitinated protein aggregates towards the autophagy pathway
When a p62 mutant p62(ΔZZ–LIM protein-binding domain (LB)), lacking domains seemingly nonessential for p62 body formation, i.e., ZZ and LB domains (Fig. 1a), was transiently transfected for testing its ability to form the p62 body in p62 knockout HeLa cells (HeLa/p62KO; Supplementary Fig. 1a–e), we observed that p62 body formation by the mutant is not as efficient as that by wild type (WT): the p62 bodies formed by the mutant were smaller in size and number compared to those formed by the WT protein (Fig. 1b)
The mutation led to decrease in the number and size of p62 bodies (Supplementary Fig. 2c, d), suggesting that these domains may contribute to p62 body formation

Summary

Introduction

P62/SQSTM1 is known to act as a key mediator in the selective autophagy of protein aggregates, or aggrephagy, by steering ubiquitinated protein aggregates towards the autophagy pathway. We show that UXT can bind to protein aggregates as well as the LB domain of p62, and, possibly by forming an oligomer, increase p62 clustering for its efficient targeting to protein aggregates, thereby promoting the formation of the p62 body and clearance of its cargo via autophagy. We find that ectopic expression of human UXT delays SOD1(A4V)-induced degeneration of motor neurons in a Xenopus model system, and that specific disruption of the interaction between UXT and p62 suppresses UXT-mediated protection. Together, these results indicate that UXT functions as an autophagy adaptor of p62-dependent aggrephagy.

Methods

Results

Conclusion