Novel Ubiquitin Specific Protease-13 Inhibitors Alleviate Neurodegenerative Pathology

Abstract

Ubiquitin Specific Protease-13 (USP13) promotes protein de-ubiquitination and is poorly understood in neurodegeneration. USP13 is upregulated in Alzheimer’s disease (AD) and Parkinson’s disease (PD), and USP13 knockdown via shRNA reduces neurotoxic proteins and increases proteasome activity in models of neurodegeneration. We synthesized novel analogues of spautin-1 which is a non-specific USP13 inhibitor but unable to penetrate the brain. Our synthesized small molecule compounds are able to enter the brain, more potently inhibit USP13, and significantly reduce alpha-synuclein levels in vivo and in vitro. USP13 inhibition in transgenic mutant alpha-synuclein (A53T) mice increased the ubiquitination of alpha-synuclein and reduced its protein levels. The data suggest that novel USP13 inhibitors improve neurodegenerative pathology via antagonism of de-ubiquitination, thus alleviating neurotoxic protein burden in neurodegenerative diseases.

USP13: Multiple Functions and Target Inhibition

“…Consistently, knockdown or pharmacological inhibition of USP13 by spautin-1 retards the growth, differentiation and invasion of many tumors, providing a possibility for antagonizing the drug resistance of tumor cells. Furthermore, recent studies have shown that derivatives of spautin-1 display better USP13 inhibition and the ability to cross the blood-brain barrier, which is presumably beneficial for research on USP13-related neurodegenerative disease ( Liu et al, 2021a ). However, here a few critical issues are raised.…”

“…More lately, a new study on USP13 inhibitors was reported. Liu et al designed and synthesized six derivatives of spautin-1 ( Figure 4B ), which exhibit higher inhibition efficiency against USP13 ( Figure 4C ) and capability of crossing the blood-brain barrier ( Liu et al, 2021a ), compared to spautin-1, enabling the development of inhibitors in neurodegenerative diseases. They first treated neuroblastoma SH-SY5Y cells with six inhibitors at a concentration ranging from 1 nM to 1 mM, and detected USP13 activity utilizing ELISA assay.…”

“…Albeit the structures of full-length USP13, as well as its catalytic structural domain have not been obtained, structures of several functional domains are determined ( Liu et al, 2011 ; Zhang et al, 2011 ; Liu et al, 2014 ; Han et al, 2016 ). Given the implications of USP13 in tumorigenesis, seeking compounds that modulate the USP13 emerges an active area of research and achieves impressive progress, with multiple selective compounds being identified successively by both research institutions and pharmaceutical companies ( Liu et al, 2011 ; Liu et al, 2021a ).…”

Inhibition of Ubiquitin-Specific Protease-13 Improves Behavioral Performance in Alpha-Synuclein Expressing Mice

“…Ubiquitin-Specific Protease (USP)-13 is critical in the regulation of protein clearance mechanisms in models of Parkinson’s disease (PD) [ 1 , 2 ]. USP13 reduces the E3 ubiquitin ligase activity of parkin via de-ubiquitination [ 1 , 2 ], while USP13 knockdown increases parkin ubiquitination and activity and reduces alpha-synuclein levels [ 1 , 2 ]. USP13 may also be critical for the regulation of other E3 ubiquitin ligases that are implicated in PD pathology, including NEDD4 [ 3 ].…”

“…shRNAs targeting USP13 expression reduces alpha-synuclein via autophagy and or the proteasome in vivo and in vitro [ 1 , 5 ]. Knockdown via shRNA and pharmacological inhibition of USP13 increase clearance of ubiquitinited alpha-synuclein [ 1 , 2 , 5 ]. When taken together, these findings suggest a role of USP13 in alpha-synuclein-associated pathology.…”