1
|
Lv P, Liu J, Liu X. The role of ubiquitin-conjugating enzyme in the process of spermatogenesis. Reprod Biol Endocrinol 2024; 22:110. [PMID: 39198846 PMCID: PMC11351103 DOI: 10.1186/s12958-024-01282-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Accepted: 08/15/2024] [Indexed: 09/01/2024] Open
Abstract
The ubiquitination is crucial for controlling cellular homeostasis and protein modification, in which ubiquitin-conjugating enzyme (E2) acts as the central player in the ubiquitination system. Ubiquitin-conjugating enzymes, which have special domains that catalyse substrates, have sequence discrepancies and modulate various pathophysiological processes in different cells of multiple organisms. E2s take part in the mitosis of primordial germ cells, meiosis of spermatocytes and the formation of mature haploid spermatids to maintain normal male fertility. In this review, we summarize the various types of E2s and their functions during distinct stages of spermatogenesis.
Collapse
Affiliation(s)
- Peng Lv
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Institute of Andrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jihong Liu
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
- Institute of Andrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Xiaming Liu
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
- Institute of Andrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| |
Collapse
|
2
|
Rodríguez Pérez F, Natwick D, Schiff L, McSwiggen D, Heckert A, Huey M, Morrison H, Loo M, Miranda RG, Filbin J, Ortega J, Van Buren K, Murnock D, Tao A, Butler R, Cheng K, Tarvestad W, Zhang Z, Gonzalez E, Miller RM, Kelly M, Tang Y, Ho J, Anderson D, Bashore C, Basham S. WRN inhibition leads to its chromatin-associated degradation via the PIAS4-RNF4-p97/VCP axis. Nat Commun 2024; 15:6059. [PMID: 39025847 PMCID: PMC11258360 DOI: 10.1038/s41467-024-50178-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 07/01/2024] [Indexed: 07/20/2024] Open
Abstract
Synthetic lethality provides an attractive strategy for developing targeted cancer therapies. For example, cancer cells with high levels of microsatellite instability (MSI-H) are dependent on the Werner (WRN) helicase for survival. However, the mechanisms that regulate WRN spatiotemporal dynamics remain poorly understood. Here, we used single-molecule tracking (SMT) in combination with a WRN inhibitor to examine WRN dynamics within the nuclei of living cancer cells. WRN inhibition traps the helicase on chromatin, requiring p97/VCP for extraction and proteasomal degradation in a MSI-H dependent manner. Using a phenotypic screen, we identify the PIAS4-RNF4 axis as the pathway responsible for WRN degradation. Finally, we show that co-inhibition of WRN and SUMOylation has an additive toxic effect in MSI-H cells and confirm the in vivo activity of WRN inhibition using an MSI-H mouse xenograft model. This work elucidates a regulatory mechanism for WRN that may facilitate identification of new therapeutic modalities, and highlights the use of SMT as a tool for drug discovery and mechanism-of-action studies.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Mandy Loo
- Eikon Therapeutics, Hayward, CA, 94545, USA
| | | | | | | | | | | | - Arnold Tao
- Eikon Therapeutics, Hayward, CA, 94545, USA
| | | | | | | | | | | | | | | | | | - Jaclyn Ho
- Eikon Therapeutics, Hayward, CA, 94545, USA
| | | | | | | |
Collapse
|
3
|
Her J, Zheng H, Bunting SF. RNF4 sustains Myc-driven tumorigenesis by facilitating DNA replication. J Clin Invest 2024; 134:e167419. [PMID: 38530355 PMCID: PMC11093604 DOI: 10.1172/jci167419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/20/2024] [Indexed: 03/27/2024] Open
Abstract
The mammalian SUMO-targeted E3 ubiquitin ligase Rnf4 has been reported to act as a regulator of DNA repair, but the importance of RNF4 as a tumor suppressor has not been tested. Using a conditional-knockout mouse model, we deleted Rnf4 in the B cell lineage to test the importance of RNF4 for growth of somatic cells. Although Rnf4-conditional-knockout B cells exhibited substantial genomic instability, Rnf4 deletion caused no increase in tumor susceptibility. In contrast, Rnf4 deletion extended the healthy lifespan of mice expressing an oncogenic c-myc transgene. Rnf4 activity is essential for normal DNA replication, and in its absence, there was a failure in ATR-CHK1 signaling of replication stress. Factors that normally mediate replication fork stability, including members of the Fanconi anemia gene family and the helicases PIF1 and RECQL5, showed reduced accumulation at replication forks in the absence of RNF4. RNF4 deficiency also resulted in an accumulation of hyper-SUMOylated proteins in chromatin, including members of the SMC5/6 complex, which contributes to replication failure by a mechanism dependent on RAD51. These findings indicate that RNF4, which shows increased expression in multiple human tumor types, is a potential target for anticancer therapy, especially in tumors expressing c-myc.
Collapse
Affiliation(s)
- Joonyoung Her
- Department of Molecular Biology and Biochemistry and
| | - Haiyan Zheng
- Biological Mass Spectrometry Facility, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | | |
Collapse
|
4
|
Lee HS, Bang I, You J, Jeong TK, Kim CR, Hwang M, Kim JS, Baek SH, Song JJ, Choi HJ. Molecular basis for PHF7-mediated ubiquitination of histone H3. Genes Dev 2023; 37:984-997. [PMID: 37993255 PMCID: PMC10760634 DOI: 10.1101/gad.350989.123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023]
Abstract
The RING-type E3 ligase has been known for over two decades, yet its diverse modes of action are still the subject of active research. Plant homeodomain (PHD) finger protein 7 (PHF7) is a RING-type E3 ubiquitin ligase responsible for histone ubiquitination. PHF7 comprises three zinc finger domains: an extended PHD (ePHD), a RING domain, and a PHD. While the function of the RING domain is largely understood, the roles of the other two domains in E3 ligase activity remain elusive. Here, we present the crystal structure of PHF7 in complex with the E2 ubiquitin-conjugating enzyme (E2). Our structure shows that E2 is effectively captured between the RING domain and the C-terminal PHD, facilitating E2 recruitment through direct contact. In addition, through in vitro binding and functional assays, we demonstrate that the N-terminal ePHD recognizes the nucleosome via DNA binding, whereas the C-terminal PHD is involved in histone H3 recognition. Our results provide a molecular basis for the E3 ligase activity of PHF7 and uncover the specific yet collaborative contributions of each domain to the PHF7 ubiquitination activity.
Collapse
Affiliation(s)
- Hyun Sik Lee
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Injin Bang
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, New York 10016, USA
| | - Junghyun You
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Tae-Kyeong Jeong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Chang Rok Kim
- Creative Research Initiatives Center for Epigenetic Code and Diseases, School of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Minsang Hwang
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jong-Seo Kim
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Sung Hee Baek
- Creative Research Initiatives Center for Epigenetic Code and Diseases, School of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Ji-Joon Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Hee-Jung Choi
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea;
| |
Collapse
|
5
|
Cabello-Lobato MJ, Jenner M, Cisneros-Aguirre M, Brüninghoff K, Sandy Z, da Costa I, Jowitt T, Loch C, Jackson S, Wu Q, Mootz H, Stark J, Cliff M, Schmidt C. Microarray screening reveals two non-conventional SUMO-binding modules linked to DNA repair by non-homologous end-joining. Nucleic Acids Res 2022; 50:4732-4754. [PMID: 35420136 PMCID: PMC9071424 DOI: 10.1093/nar/gkac237] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/03/2022] [Accepted: 03/25/2022] [Indexed: 11/25/2022] Open
Abstract
SUMOylation is critical for numerous cellular signalling pathways, including the maintenance of genome integrity via the repair of DNA double-strand breaks (DSBs). If misrepaired, DSBs can lead to cancer, neurodegeneration, immunodeficiency and premature ageing. Using systematic human proteome microarray screening combined with widely applicable carbene footprinting, genetic code expansion and high-resolution structural profiling, we define two non-conventional and topology-selective SUMO2-binding regions on XRCC4, a DNA repair protein important for DSB repair by non-homologous end-joining (NHEJ). Mechanistically, the interaction of SUMO2 and XRCC4 is incompatible with XRCC4 binding to three other proteins important for NHEJ-mediated DSB repair. These findings are consistent with SUMO2 forming a redundant NHEJ layer with the potential to regulate different NHEJ complexes at distinct levels including, but not limited to, XRCC4 interactions with XLF, LIG4 and IFFO1. Regulation of NHEJ is not only relevant for carcinogenesis, but also for the design of precision anti-cancer medicines and the optimisation of CRISPR/Cas9-based gene editing. In addition to providing molecular insights into NHEJ, this work uncovers a conserved SUMO-binding module and provides a rich resource on direct SUMO binders exploitable towards uncovering SUMOylation pathways in a wide array of cellular processes.
Collapse
Affiliation(s)
- Maria Jose Cabello-Lobato
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| | - Matthew Jenner
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
- Warwick Integrative Synthetic Biology (WISB) Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Irell and Manella Graduate School of Biological Sciences Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Kira Brüninghoff
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149 Muenster, Germany
| | - Zac Sandy
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| | - Isabelle C da Costa
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| | - Thomas A Jowitt
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | | | - Stephen P Jackson
- Wellcome/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge CB2 1QN, UK
| | - Qian Wu
- Astbury Centre for Structural Molecular Biology, School of Molecular & Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Henning D Mootz
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149 Muenster, Germany
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Irell and Manella Graduate School of Biological Sciences Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Matthew J Cliff
- Manchester Institute of Biotechnology (MIB) and School of Chemistry, University of Manchester, Manchester M1 7DN, UK
| | - Christine K Schmidt
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK
| |
Collapse
|
6
|
Taillandier D. [Metabolic pathways controlled by E3 ligases: an opportunity for therapeutic targeting]. Biol Aujourdhui 2021; 215:45-57. [PMID: 34397374 DOI: 10.1051/jbio/2021006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Indexed: 11/14/2022]
Abstract
Since its discovery, the Ubiquitin Proteasome System (UPS) has been recognized for its major role in controlling most of the cell's metabolic pathways. In addition to its essential role in the degradation of proteins, it is also involved in the addressing, signaling or repair of DNA, which makes it a key player in cellular homeostasis. Although other control systems exist in the cell, the UPS is often referred to as the conductor. In view of its importance, any dysregulation of the UPS leads to more or less severe disorders for the cell and therefore the body, which accounts for UPS implication in many pathologies (cancer, Alzheimer's disease, Huntington's disease, etc.). UPS is made up of more than 1000 different proteins, the combinations of which allow the fine targeting of virtually all proteins in the body. UPS uses an enzymatic cascade (E1, 2 members; E2 > 35; E3 > 800) which allows the transfer of ubiquitin, a small protein of 8.5 kDa onto the protein to be targeted either for its degradation or to modify its activity. This ubiquitinylation signal is reversible and many deubiquitinylases (DUB, ∼ 80 isoforms) also have an important role. E3 enzymes are the most numerous and their function is to recognize the target protein, which makes them important players in the specific action of UPS. The very nature of E3 and the complexity of their interactions with different partners offer a very broad field of investigation and therefore significant potential for the development of therapeutic approaches. Without being exhaustive, this review illustrates the different strategies that have already been implemented to fight against different pathologies (excluding bacterial or viral infections).
Collapse
Affiliation(s)
- Daniel Taillandier
- Université Clermont Auvergne, INRAE, UNH, Unité de Nutrition Humaine, 63000 Clermont-Ferrand, France
| |
Collapse
|
7
|
Chang YC, Oram MK, Bielinsky AK. SUMO-Targeted Ubiquitin Ligases and Their Functions in Maintaining Genome Stability. Int J Mol Sci 2021; 22:ijms22105391. [PMID: 34065507 PMCID: PMC8161396 DOI: 10.3390/ijms22105391] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 02/06/2023] Open
Abstract
Small ubiquitin-like modifier (SUMO)-targeted E3 ubiquitin ligases (STUbLs) are specialized enzymes that recognize SUMOylated proteins and attach ubiquitin to them. They therefore connect the cellular SUMOylation and ubiquitination circuits. STUbLs participate in diverse molecular processes that span cell cycle regulated events, including DNA repair, replication, mitosis, and transcription. They operate during unperturbed conditions and in response to challenges, such as genotoxic stress. These E3 ubiquitin ligases modify their target substrates by catalyzing ubiquitin chains that form different linkages, resulting in proteolytic or non-proteolytic outcomes. Often, STUbLs function in compartmentalized environments, such as the nuclear envelope or kinetochore, and actively aid in nuclear relocalization of damaged DNA and stalled replication forks to promote DNA repair or fork restart. Furthermore, STUbLs reside in the same vicinity as SUMO proteases and deubiquitinases (DUBs), providing spatiotemporal control of their targets. In this review, we focus on the molecular mechanisms by which STUbLs help to maintain genome stability across different species.
Collapse
|
8
|
Abstract
OTUB1 is a highly expressed cysteine protease that specifically cleaves K48-linked polyubiquitin chains. This unique deubiquitinating enzyme (DUB) can bind to a subset of E2 ubiquitin conjugating enzymes, forming complexes in which the two enzymes can regulate one another's activity. OTUB1 can noncatalytically suppress the ubiquitin conjugating activity of its E2 partners by sequestering the charged E2∼Ub thioester and preventing ubiquitin transfer. The same E2 enzymes, when uncharged, can stimulate the DUB activity of OTUB1 in vitro, although the importance of OTUB1 stimulation in vivo remains unclear. To assess the potential balance between these activities that might occur in cells, we characterized the kinetics and thermodynamics governing the formation and activity of OTUB1:E2 complexes. We show that both stimulation of OTUB1 by E2 enzymes and noncatalytic inhibition of E2 enzymes by OTUB1 occur at physiologically relevant concentrations of both partners. Whereas E2 partners differ in their ability to stimulate OTUB1 activity, we find that this variability is not correlated with the affinity of each E2 for OTUB1. In addition to UBE2N and the UBE2D isoforms, we find that OTUB1 inhibits the polyubiquitination activity of all three UBE2E enzymes, UBE2E1, UBE2E2, and UBE2E3. Interestingly, although OTUB1 also inhibits the auto-monoubiquitination and autopolyubiquitination activity of UBE2E1 and UBE2E2, it is unable to suppress autoubiquitination by UBE2E3. Our quantitative analysis provides a basis for further exploring the biological roles of OTUB1:E2 complexes in cells.
Collapse
Affiliation(s)
- Lauren T. Que
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21210-2185 USA
| | - Marie E. Morrow
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21210-2185 USA
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21210-2185 USA
| |
Collapse
|
9
|
Pasupala N, Morrow ME, Que LT, Malynn BA, Ma A, Wolberger C. OTUB1 non-catalytically stabilizes the E2 ubiquitin-conjugating enzyme UBE2E1 by preventing its autoubiquitination. J Biol Chem 2018; 293:18285-18295. [PMID: 30282802 PMCID: PMC6254341 DOI: 10.1074/jbc.ra118.004677] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/04/2018] [Indexed: 01/08/2023] Open
Abstract
OTUB1 is a deubiquitinating enzyme that cleaves Lys-48–linked polyubiquitin chains and also regulates ubiquitin signaling through a unique, noncatalytic mechanism. OTUB1 binds to a subset of E2 ubiquitin-conjugating enzymes and inhibits their activity by trapping the E2∼ubiquitin thioester and preventing ubiquitin transfer. The same set of E2s stimulate the deubiquitinating activity of OTUB1 when the E2 is not charged with ubiquitin. Previous studies have shown that, in cells, OTUB1 binds to E2-conjugating enzymes of the UBE2D (UBCH5) and UBE2E families, as well as to UBE2N (UBC13). Cellular roles have been identified for the interaction of OTUB1 with UBE2N and members of the UBE2D family, but not for interactions with UBE2E E2 enzymes. We report here a novel role for OTUB1–E2 interactions in modulating E2 protein ubiquitination. We observe that Otub1−/− knockout mice exhibit late-stage embryonic lethality. We find that OTUB1 depletion dramatically destabilizes the E2-conjugating enzyme UBE2E1 (UBCH6) in both mouse and human OTUB1 knockout cell lines. Of note, this effect is independent of the catalytic activity of OTUB1, but depends on its ability to bind to UBE2E1. We show that OTUB1 suppresses UBE2E1 autoubiquitination in vitro and in cells, thereby preventing UBE2E1 from being targeted to the proteasome for degradation. Taken together, we provide evidence that OTUB1 rescues UBE2E1 from degradation in vivo.
Collapse
Affiliation(s)
- Nagesh Pasupala
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185 and
| | - Marie E Morrow
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185 and
| | - Lauren T Que
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185 and
| | - Barbara A Malynn
- the Department of Medicine, University of California San Francisco, San Francisco, California 94117
| | - Averil Ma
- the Department of Medicine, University of California San Francisco, San Francisco, California 94117
| | - Cynthia Wolberger
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185 and.
| |
Collapse
|
10
|
Structural insights into the nanomolar affinity of RING E3 ligase ZNRF1 for Ube2N and its functional implications. Biochem J 2018; 475:1569-1582. [PMID: 29626159 PMCID: PMC5941314 DOI: 10.1042/bcj20170909] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 01/10/2023]
Abstract
RING (Really Interesting New Gene) domains in ubiquitin RING E3 ligases exclusively engage ubiquitin (Ub)-loaded E2s to facilitate ubiquitination of their substrates. Despite such specificity, all RINGs characterized till date bind unloaded E2s with dissociation constants (Kds) in the micromolar to the sub-millimolar range. Here, we show that the RING domain of E3 ligase ZNRF1, an essential E3 ligase implicated in diverse cellular pathways, binds Ube2N with a Kd of ∼50 nM. This high-affinity interaction is exclusive for Ube2N as ZNRF1 interacts with Ube2D2 with a Kd of ∼1 µM, alike few other E3s. The crystal structure of ZNRF1 C-terminal domain in complex with Ube2N coupled with mutational analyses reveals the molecular basis of this unusual affinity. We further demonstrate that the ubiquitination efficiency of ZNRF1 : E2 pairs correlates with their affinity. Intriguingly, as a consequence of its high E2 affinity, an excess of ZNRF1 inhibits Ube2N-mediated ubiquitination at concentrations ≥500 nM instead of showing enhanced ubiquitination. This suggests a novel mode of activity regulation of E3 ligases and emphasizes the importance of E3-E2 balance for the optimum activity. Based on our results, we propose that overexpression-based functional analyses on E3 ligases such as ZNRF1 must be approached with caution as enhanced cellular levels might result in aberrant modification activity.
Collapse
|
11
|
Diefenbacher M, Orian A. Stabilization of nuclear oncoproteins by RNF4 and the ubiquitin system in cancer. Mol Cell Oncol 2016; 4:e1260671. [PMID: 28197534 PMCID: PMC5287002 DOI: 10.1080/23723556.2016.1260671] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 11/09/2016] [Accepted: 11/09/2016] [Indexed: 06/06/2023]
Abstract
RNF4, a SUMO-targeted ubiquitin ligase, stabilizes a selected group of oncoproteins. It potentiates oncoprotein activity and serves as a positive feedback agonist of Wnt and Notch pathways. RNF4 is essential for cancer cell survival and its levels are elevated in human cancers, correlating with poor outcome in a subset of cancer patients.
Collapse
Affiliation(s)
| | - A. Orian
- Rappaport Research Institute and Faculty of Medicine, TICC, Technion – Israel Institute of Technology, Haifa, Israel
| |
Collapse
|