TOP1
DNA topoisomerase 1 (EC 5.6.2.1) (DNA topoisomerase I)
Publications[править]
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.
MeSH Terms
- Cell Line, Tumor
- Chromosome Breakage
- Cysteine Endopeptidases
- DNA Repair
- DNA Topoisomerases, Type I
- Down-Regulation
- HEK293 Cells
- Humans
- Nucleotidases
- Phosphoric Diester Hydrolases
- Proteostasis
- RNA Interference
- RNA, Small Interfering
- Ubiquitin
- Ubiquitin Thiolesterase
- Ubiquitination
- Up-Regulation
Keywords
- SCAN1
- TDP
- UCHL3
- aging
- cancer
- heart failure
- myocardial infarction
- neurodegeneration
- rhabdosarcoma
- topoisomerase
MicroRNAs (miRNAs) are a group of small non-coding executor RNAs. Their function as key modulators of cellular senescence has been widely recognized recently. By cross-comparing several human aging models we previously identified dozens of miRNAs being differentially regulated during aging. Here the functions of two miRNAs, mir-24 and mir-424, were investigated in an oxidative stress-induced fibroblast premature senescence model. Using pre-miRNA precursors, miRNAs were overexpressed in cells undergoing premature senescence induced by oxidative stress. More senescent cells were observed in mir-24 transfected cells. p53 was upregulated in mir-24 overexpressing cells, but downregulated in mir-424 overexpressing cells. DNA topoisomerase I (TOP1), an enzyme controlling DNA topology, was identified as a target of mir-24, whose expression was induced by oxidative stress. Knocking down TOP1 induced cellular senescence. These results suggest that mir-24 activity propagates stress-induced senescence by down regulating TOP1.
MeSH Terms
- Cells, Cultured
- Cellular Senescence
- DNA Topoisomerases, Type I
- Down-Regulation
- Fibroblasts
- Gene Expression Regulation
- Humans
- MicroRNAs
- Oxidative Stress
- Transfection
Keywords
- Cellular senescence
- Oxidative stress
- TOP1
- miRNA
- mir-24