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Experimental Biology and Medicine... Aug 2023Ubiquitination is an intricately regulated post-translational modification that involves the covalent attachment of ubiquitin to a substrate protein. The complex dynamic... (Review)
Review
Ubiquitination is an intricately regulated post-translational modification that involves the covalent attachment of ubiquitin to a substrate protein. The complex dynamic nature of the ubiquitination process regulates diverse cellular functions including targeting proteins for degradation, cell cycle, deoxyribonucleic acid (DNA) damage repair, and numerous cell signaling pathways. Ubiquitination also serves as a crucial mechanism in protein quality control. Dysregulation in ubiquitination could result in lethal disease conditions such as cancers and neurodegenerative diseases. Therefore, the ubiquitination cascade has become an attractive target for therapeutic interventions. Enormous efforts have been made to detect ubiquitination involving different detection techniques to better grasp the underlying molecular mechanisms of ubiquitination. This review discusses a wide range of techniques stretching from the simplest assays to real-time assays. This includes western blotting/immunoblotting, fluorescence assays, chemiluminescence assays, spectrophotometric assays, and nanopore sensing assays. This review compares these applications, and the inherent advantages and limitations.
Topics: Ubiquitination; Ubiquitin; Proteins; Protein Processing, Post-Translational; Ubiquitin-Protein Ligases
PubMed: 37787047
DOI: 10.1177/15353702231191186 -
Nature Communications Jul 2023KRAS is a frequent driver in lung cancer. To identify KRAS-specific vulnerabilities in lung cancer, we performed RNAi screens in primary spheroids derived from a Kras...
KRAS is a frequent driver in lung cancer. To identify KRAS-specific vulnerabilities in lung cancer, we performed RNAi screens in primary spheroids derived from a Kras mutant mouse lung cancer model and discovered an epigenetic regulator Ubiquitin-like containing PHD and RING finger domains 1 (UHRF1). In human lung cancer models UHRF1 knock-out selectively impaired growth and induced apoptosis only in KRAS mutant cells. Genome-wide methylation and gene expression analysis of UHRF1-depleted KRAS mutant cells revealed global DNA hypomethylation leading to upregulation of tumor suppressor genes (TSGs). A focused CRISPR/Cas9 screen validated several of these TSGs as mediators of UHRF1-driven tumorigenesis. In vivo, UHRF1 knock-out inhibited tumor growth of KRAS-driven mouse lung cancer models. Finally, in lung cancer patients high UHRF1 expression is anti-correlated with TSG expression and predicts worse outcomes for patients with KRAS mutant tumors. These results nominate UHRF1 as a KRAS-specific vulnerability and potential target for therapeutic intervention.
Topics: Animals; Humans; Mice; Adenocarcinoma of Lung; CCAAT-Enhancer-Binding Proteins; Cell Transformation, Neoplastic; DNA Methylation; Epigenesis, Genetic; Lung Neoplasms; Proto-Oncogene Proteins p21(ras); Ubiquitin-Protein Ligases
PubMed: 37407562
DOI: 10.1038/s41467-023-39591-2 -
Nature Communications Dec 2023Cyclic GMP-AMP synthase (cGAS), initially identified as a cytosolic DNA sensor, detects DNA fragments to trigger an innate immune response. Recently, accumulating...
Cyclic GMP-AMP synthase (cGAS), initially identified as a cytosolic DNA sensor, detects DNA fragments to trigger an innate immune response. Recently, accumulating evidence reveals the presence of cGAS within the nucleus. However, the biological functions of nuclear cGAS are not fully understood. Here, we demonstrate that nuclear cGAS represses LINE-1 (L1) retrotransposition to preserve genome integrity in human cells. Mechanistically, the E3 ligase TRIM41 interacts with and ubiquitinates ORF2p to influence its stability, and cGAS enhances the association of ORF2p with TRIM41, thereby promoting TRIM41-mediated ORF2p degradation and the suppression of L1 retrotransposition. In response to DNA damage, cGAS is phosphorylated at serine residues 120 and 305 by CHK2, which promotes cGAS-TRIM41 association, facilitating TRIM41-mediated ORF2p degradation. Moreover, we show that nuclear cGAS mediates the repression of L1 retrotransposition in senescent cells induced by DNA damage agents. We also identify several cancer-associated cGAS mutations that abolish the suppressive effect on L1 retrotransposition by disrupting the CHK2-cGAS-TRIM41-ORF2p regulatory axis. Together, these findings indicate that nuclear cGAS exhibits an inhibitory function in L1 retrotransposition which could provide avenues for future interventions in both aging and tumorigenesis.
Topics: Humans; DNA; Long Interspersed Nucleotide Elements; Nucleotidyltransferases; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 38086852
DOI: 10.1038/s41467-023-43001-y -
Nature Aug 2023Human tripartite motif protein 5α (TRIM5α) is a well-characterized restriction factor for some RNA viruses, including HIV; however, reports are limited for DNA...
Human tripartite motif protein 5α (TRIM5α) is a well-characterized restriction factor for some RNA viruses, including HIV; however, reports are limited for DNA viruses. Here we demonstrate that TRIM5α also restricts orthopoxviruses and, via its SPRY domain, binds to the orthopoxvirus capsid protein L3 to diminish virus replication and activate innate immunity. In response, several orthopoxviruses, including vaccinia, rabbitpox, cowpox, monkeypox, camelpox and variola viruses, deploy countermeasures. First, the protein C6 binds to TRIM5 via the RING domain to induce its proteasome-dependent degradation. Second, cyclophilin A (CypA) is recruited via interaction with the capsid protein L3 to virus factories and virions to antagonize TRIM5α; this interaction is prevented by cyclosporine A (CsA) and the non-immunosuppressive derivatives alisporivir and NIM811. Both the proviral effect of CypA and the antiviral effect of CsA are dependent on TRIM5α. CsA, alisporivir and NIM811 have antiviral activity against orthopoxviruses, and because these drugs target a cellular protein, CypA, the emergence of viral drug resistance is difficult. These results warrant testing of CsA derivatives against orthopoxviruses, including monkeypox and variola.
Topics: Humans; Antiviral Agents; Antiviral Restriction Factors; Capsid Proteins; Cell Line; Cyclophilin A; Poxviridae; Tripartite Motif Proteins; Ubiquitin-Protein Ligases; Viral Proteins; Proteasome Endopeptidase Complex
PubMed: 37558876
DOI: 10.1038/s41586-023-06401-0 -
Annals of Medicine Dec 2023Glioma is a common primary central nervous system tumor with complex pathogenesis. DNA damage and repair (DDR) is widely involved in regulating cell proliferation and...
BACKGROUND
Glioma is a common primary central nervous system tumor with complex pathogenesis. DNA damage and repair (DDR) is widely involved in regulating cell proliferation and tumorigenesis by correcting and repairing DNA damage mechanisms. Recent studies have reported the following properties in cancer cells in glioma, increased DNA damage and reduced DNA repair capacity. However, the relationship between glioma and DDR-related genes was unclear.
METHODS
DDR-related risk score model was built. The validity of this model was validated in detail through the Kaplan-Meier survival analysis, tumor mutational burden (TMB) analysis, immune cell infiltration, sensitivity to treatment regimens. Moreover, the model's adaptability was validated in different glioma data cohorts and different glioma subgroups. To further investigate the molecular mechanism of one of DDR-related gene (NUDT1) in glioma, U251 cell was used for the knockdown experiment, followed by MTT, wound healing and transwell analysis.
RESULTS
Ten prognostic-related DDR-related signature genes were obtained, including EID3, MGMT, YWHAG, PMS1, SHPRH, HUS1, NUDT1, GADD45G, APEX1 and FAM175A. The RT-qPCR results suggested that the latter five genes were highly expressed in glioma patients. Interestingly, high TMB score had longer survival. In high-risk score groups, reduced immune cell infiltration in the tumor microenvironment lead to poorer patient outcomes. Sensitivity to treatment regimens analysis indicated that low-risk score groups were more sensitive to chemotherapeutics. Moreover, the risk score model had a good prediction effect on different glioma datasets and different glioma subgroups. mechanism study showed that knockdown of NUDT1 reduced tumorigenesis. Furthermore, knockdown of NUDT1 remarkably reduced the expression level of HIF-1α.
CONCLUSION
DDR-related risk score model built-in this work has good predictive performance for glioma.Key messagesTen prognostic-related DDR-related signature genes were obtained, including EID3, MGMT, YWHAG, PMS1, SHPRH, HUS1, NUDT1, GADD45G, APEX1 and FAM175A.In high-risk score groups, reduced immune cell infiltration in the tumor microenvironment leads to poorer patient outcomes.The risk score model had a good prediction effect on different glioma datasets and different glioma subgroups.Knockdown of NUDT1 reduced tumorigenesis of glioma and remarkably reduced the expression level of HIF-1α.
Topics: Humans; Risk Factors; Carcinogenesis; Cell Transformation, Neoplastic; DNA Damage; Glioma; Prognosis; Tumor Microenvironment; DNA Helicases; Ubiquitin-Protein Ligases; 14-3-3 Proteins
PubMed: 37086071
DOI: 10.1080/07853890.2023.2200033 -
Nature Mar 2024Cyclic GMP-AMP synthase (cGAS) senses aberrant DNA during infection, cancer and inflammatory disease, and initiates potent innate immune responses through the synthesis...
Cyclic GMP-AMP synthase (cGAS) senses aberrant DNA during infection, cancer and inflammatory disease, and initiates potent innate immune responses through the synthesis of 2'3'-cyclic GMP-AMP (cGAMP). The indiscriminate activity of cGAS towards DNA demands tight regulatory mechanisms that are necessary to maintain cell and tissue homeostasis under normal conditions. Inside the cell nucleus, anchoring to nucleosomes and competition with chromatin architectural proteins jointly prohibit cGAS activation by genomic DNA. However, the fate of nuclear cGAS and its role in cell physiology remains unclear. Here we show that the ubiquitin proteasomal system (UPS) degrades nuclear cGAS in cycling cells. We identify SPSB3 as the cGAS-targeting substrate receptor that associates with the cullin-RING ubiquitin ligase 5 (CRL5) complex to ligate ubiquitin onto nuclear cGAS. A cryo-electron microscopy structure of nucleosome-bound cGAS in a complex with SPSB3 reveals a highly conserved Asn-Asn (NN) minimal degron motif at the C terminus of cGAS that directs SPSB3 recruitment, ubiquitylation and cGAS protein stability. Interference with SPSB3-regulated nuclear cGAS degradation primes cells for type I interferon signalling, conferring heightened protection against infection by DNA viruses. Our research defines protein degradation as a determinant of cGAS regulation in the nucleus and provides structural insights into an element of cGAS that is amenable to therapeutic exploitation.
Topics: Animals; Humans; Mice; Cell Nucleus; Cryoelectron Microscopy; Degrons; DNA Virus Infections; DNA Viruses; DNA, Viral; Immunity, Innate; Innate Immunity Recognition; Interferon Type I; Nuclear Proteins; Nucleosomes; Nucleotidyltransferases; Proteasome Endopeptidase Complex; Protein Stability; Proteolysis; Substrate Specificity; Ubiquitin; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 38418882
DOI: 10.1038/s41586-024-07112-w -
Cell Host & Microbe Jul 2023Targeted protein degradation (TPD), as exemplified by proteolysis-targeting chimera (PROTAC), is an emerging drug discovery platform. PROTAC molecules, which typically...
Targeted protein degradation (TPD), as exemplified by proteolysis-targeting chimera (PROTAC), is an emerging drug discovery platform. PROTAC molecules, which typically contain a target protein ligand linked to an E3 ligase ligand, recruit a target protein to the E3 ligase to induce its ubiquitination and degradation. Here, we applied PROTAC approaches to develop broad-spectrum antivirals targeting key host factors for many viruses and virus-specific antivirals targeting unique viral proteins. For host-directed antivirals, we identified a small-molecule degrader, FM-74-103, that elicits selective degradation of human GSPT1, a translation termination factor. FM-74-103-mediated GSPT1 degradation inhibits both RNA and DNA viruses. Among virus-specific antivirals, we developed viral RNA oligonucleotide-based bifunctional molecules (Destroyers). As a proof of principle, RNA mimics of viral promoter sequences were used as heterobifunctional molecules to recruit and target influenza viral polymerase for degradation. This work highlights the broad utility of TPD to rationally design and develop next-generation antivirals.
Topics: Humans; Antiviral Agents; Proteolysis; RNA, Viral; Ligands; Viruses; Ubiquitin-Protein Ligases; Viral Proteins; Carrier Proteins
PubMed: 37339625
DOI: 10.1016/j.chom.2023.05.030 -
Molecular Cell Dec 2023Reactive aldehydes are produced by normal cellular metabolism or after alcohol consumption, and they accumulate in human tissues if aldehyde clearance mechanisms are...
Reactive aldehydes are produced by normal cellular metabolism or after alcohol consumption, and they accumulate in human tissues if aldehyde clearance mechanisms are impaired. Their toxicity has been attributed to the damage they cause to genomic DNA and the subsequent inhibition of transcription and replication. However, whether interference with other cellular processes contributes to aldehyde toxicity has not been investigated. We demonstrate that formaldehyde induces RNA-protein crosslinks (RPCs) that stall the ribosome and inhibit translation in human cells. RPCs in the messenger RNA (mRNA) are recognized by the translating ribosomes, marked by atypical K6-linked ubiquitylation catalyzed by the RING-in-between-RING (RBR) E3 ligase RNF14, and subsequently resolved by the ubiquitin- and ATP-dependent unfoldase VCP. Our findings uncover an evolutionary conserved formaldehyde-induced stress response pathway that protects cells against RPC accumulation in the cytoplasm, and they suggest that RPCs contribute to the cellular and tissue toxicity of reactive aldehydes.
Topics: Humans; RNA; Ubiquitination; Ubiquitin-Protein Ligases; Formaldehyde; Aldehydes; RNA, Messenger
PubMed: 37951215
DOI: 10.1016/j.molcel.2023.10.011 -
Molecular Cancer Oct 2023To address the shortcomings of current hepatocellular carcinoma (HCC) surveillance tests, we set out to find HCC-specific methylation markers and develop a highly...
To address the shortcomings of current hepatocellular carcinoma (HCC) surveillance tests, we set out to find HCC-specific methylation markers and develop a highly sensitive polymerase chain reaction (PCR)-based method to detect them in circulating cell-free DNA (cfDNA). The analysis of large methylome data revealed that Ring Finger Protein 135 (RNF135) and Lactate Dehydrogenase B (LDHB) are universally applicable HCC methylation markers with no discernible methylation level detected in any other tissue types. These markers were used to develop Methylation Sensitive High-Resolution Analysis (MS-HRM), and their diagnostic accuracy was tested using cfDNA from healthy, at-risk, and HCC patients. The combined MS-HRM RNF135 and LDHB analysis detected 57% of HCC, outperforming the alpha-fetoprotein (AFP) test's sensitivity of 45% at comparable specificity. Furthermore, when used with the AFP test, the methylation assay can detect 70% of HCC. Our findings suggest that the cfDNA methylation assay could be used for HCC liquid biopsy.
Topics: Humans; Carcinoma, Hepatocellular; alpha-Fetoproteins; Liver Neoplasms; DNA Methylation; Biomarkers, Tumor; Cell-Free Nucleic Acids; Ubiquitin-Protein Ligases
PubMed: 37803338
DOI: 10.1186/s12943-023-01872-1 -
The Journal of Biological Chemistry Aug 2023The ubiquitin signaling pathway is crucial for the DNA damage response pathway. More specifically, RNF168 is integral in regulating DNA repair proteins at damaged...
The ubiquitin signaling pathway is crucial for the DNA damage response pathway. More specifically, RNF168 is integral in regulating DNA repair proteins at damaged chromatin. However, the detailed mechanism by which RNF168 is regulated in cells is not fully understood. Here, we identify the ubiquitin-ribosomal fusion proteins UBA80 (also known as RPS27A) and UBA52 (also known as RPL40) as interacting proteins for H2A/H2AX histones and RNF168. Both UBA80 and UBA52 are recruited to laser-induced micro-irradiation DNA damage sites and are required for DNA repair. Ectopic expression of UBA80 and UBA52 inhibits RNF168-mediated H2A/H2AX ubiquitination at K13/15 and impairs 53BP1 recruitment to DNA lesions. Mechanistically, the C-terminal ribosomal fragments of UBA80 and UBA52, S27A and L40, respectively, limit RNF168-nucleosome engagement by masking the regulatory acidic residues at E143/E144 and the nucleosome acidic patch. Together, our results reveal that UBA80 and UBA52 antagonize the ubiquitination signaling pathway and fine-tune the spatiotemporal regulation of DNA repair proteins at DNA damage sites.
Topics: DNA Damage; DNA Repair; Histones; Nucleosomes; Ribosomal Proteins; Ubiquitin; Ubiquitin-Protein Ligases; Ubiquitination; Humans
PubMed: 37451480
DOI: 10.1016/j.jbc.2023.105043