UCHL3 Regulates Topoisomerase-Induced Chromosomal Break Repair by Controlling TDP1 Proteostasis

• Published in: Cell reports (Cambridge) Vol. 23; no. 11; pp. 3352 - 3365
• Main Authors: Liao, Chunyan, Beveridge, Ryan, Hudson, Jessica J.R., Parker, Jacob D., Chiang, Shih-Chieh, Ray, Swagat, Ashour, Mohamed E., Sudbery, Ian, Dickman, Mark J., El-Khamisy, Sherif F.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12-06-2018; Cell Press; Elsevier
• Subjects: aging; cancer; Cell Line, Tumor; Chromosome Breakage; Cysteine Endopeptidases - chemistry; Cysteine Endopeptidases - genetics; Cysteine Endopeptidases - metabolism; DNA Repair; DNA Topoisomerases, Type I - metabolism; Down-Regulation; heart failure; HEK293 Cells; Humans; myocardial infarction; neurodegeneration; Nucleotidases - metabolism; Phosphoric Diester Hydrolases - genetics; Phosphoric Diester Hydrolases - metabolism; Proteostasis; rhabdosarcoma; RNA Interference; RNA, Small Interfering - metabolism; SCAN1; TDP; topoisomerase; Ubiquitin - metabolism; Ubiquitin Thiolesterase; Ubiquitination; UCHL3; Up-Regulation; TDP; heart failure; SCAN1; myocardial infarction; neurodegeneration; topoisomerase; cancer; aging; rhabdosarcoma; UCHL3
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2018.05.033

Genomic damage can feature DNA-protein crosslinks whereby their acute accumulation is utilized to treat cancer and progressive accumulation causes neurodegeneration. This is typified by tyrosyl DNA phosphodiesterase 1 (TDP1), which repairs topoisomerase-mediated chromosomal breaks. Although TDP1 levels vary in multiple clinical settings, the mechanism underpinning this variation is unknown. We reveal that TDP1 is controlled by ubiquitylation and identify UCHL3 as the deubiquitylase that controls TDP1 proteostasis. Depletion of UCHL3 increases TDP1 ubiquitylation and turnover rate and sensitizes cells to TOP1 poisons. Overexpression of UCHL3, but not a catalytically inactive mutant, suppresses TDP1 ubiquitylation and turnover rate. TDP1 overexpression in the topoisomerase therapy-resistant rhabdomyosarcoma is driven by UCHL3 overexpression. In contrast, UCHL3 is downregulated in spinocerebellar ataxia with axonal neuropathy (SCAN1), causing elevated levels of TDP1 ubiquitylation and faster turnover rate. These data establish UCHL3 as a regulator of TDP1 proteostasis and, consequently, a fine-tuner of protein-linked DNA break repair.
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•TDP1 proteostasis is controlled by a UCHL3-dependent ubiquitylation mechanism•UCHL3 depletion sensitizes mammalian cells to TOP1 inhibitors•Increased TDP1 protein in rhabdomyosarcoma is driven by UCHL3 upregulation•Decreased TDP1 protein in spinocerebellar ataxia is driven by UCHL3 downregulation
Deciphering the mechanisms regulating protein homeostasis is clinically important. Liao et al. identify UCHL3 as a key player in ubiquitylation and turnover of the DNA repair enzyme TDP1. Disruption of TDP1’s ubiquitylation status causes neurological disease or resistance to topoisomerase I-targeting chemotherapy in cancer.