1
|
Yon WJ, Tran JR, Ha T, Zheng Y, Pedersen RT. BuGZ exhibits guanine nucleotide exchange factor activity toward tubulin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.539990. [PMID: 37214866 PMCID: PMC10197657 DOI: 10.1101/2023.05.09.539990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
α- and β-tubulin form heterodimers, with GTPase activity, that assemble into microtubules. Like other GTPases, the nucleotide-bound state of tubulin heterodimers controls whether the molecules are in a biologically active or inactive state. While α-tubulin in the heterodimer is constitutively bound to GTP, β-tubulin can be bound to either GDP (GDP-tubulin) or GTP (GTP-tubulin). GTP-tubulin hydrolyzes its GTP to GDP following assembly into a microtubule and, upon disassembly, must exchange its bound GDP for GTP to participate in subsequent microtubule polymerization. Tubulin dimers have been shown to exhibit rapid intrinsic nucleotide exchange in vitro, leading to a commonly accepted belief that a tubulin guanine nucleotide exchange factor (GEF) may be unnecessary in cells. Here, we use quantitative binding assays to show that BuGZ, a spindle assembly factor, binds tightly to GDP-tubulin, less tightly to GTP-tubulin, and weakly to microtubules. We further show that BuGZ promotes the incorporation of GTP into tubulin using a nucleotide exchange assay. The discovery of a tubulin GEF suggests a mechanism that may aid rapid microtubule assembly dynamics in cells.
Collapse
Affiliation(s)
- Wesley J. Yon
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Joseph R. Tran
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Baltimore, MD, USA
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
| | - Ross T.A. Pedersen
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
| |
Collapse
|
2
|
Wang F, He Q, Zhan W, Yu Z, Finkin-Groner E, Ma X, Lin G, Li H. Structure of the human UBR5 E3 ubiquitin ligase. Structure 2023; 31:541-552.e4. [PMID: 37040767 PMCID: PMC10403316 DOI: 10.1016/j.str.2023.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/02/2023] [Accepted: 03/16/2023] [Indexed: 04/13/2023]
Abstract
The human UBR5 is a single polypeptide chain homology to E6AP C terminus (HECT)-type E3 ubiquitin ligase essential for embryonic development in mammals. Dysregulated UBR5 functions like an oncoprotein to promote cancer growth and metastasis. Here, we report that UBR5 assembles into a dimer and a tetramer. Our cryoelectron microscopy (cryo-EM) structures reveal that two crescent-shaped UBR5 monomers assemble head to tail to form the dimer, and two dimers bind face to face to form the cage-like tetramer with all four catalytic HECT domains facing the central cavity. Importantly, the N-terminal region of one subunit and the HECT of the other form an "intermolecular jaw" in the dimer. We show the jaw-lining residues are important for function, suggesting that the intermolecular jaw functions to recruit ubiquitin-loaded E2 to UBR5. Further work is needed to understand how oligomerization regulates UBR5 ligase activity. This work provides a framework for structure-based anticancer drug development and contributes to a growing appreciation of E3 ligase diversity.
Collapse
Affiliation(s)
- Feng Wang
- Department of Structural Biology, Van Andel Institute, 333 Bostwick Avenue NE, Grand Rapids, MI 49503, USA
| | - Qing He
- Department of Structural Biology, Van Andel Institute, 333 Bostwick Avenue NE, Grand Rapids, MI 49503, USA
| | - Wenhu Zhan
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Ziqi Yu
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Efrat Finkin-Groner
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th Street, New York, NY 10021, USA
| | - Xiaojing Ma
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Gang Lin
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, 333 Bostwick Avenue NE, Grand Rapids, MI 49503, USA.
| |
Collapse
|
3
|
Okpara MO, Hermann C, van der Watt PJ, Garnett S, Blackburn JM, Leaner VD. A mass spectrometry-based approach for the identification of Kpnβ1 binding partners in cancer cells. Sci Rep 2022; 12:20171. [PMID: 36418423 PMCID: PMC9684564 DOI: 10.1038/s41598-022-24194-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 11/11/2022] [Indexed: 11/25/2022] Open
Abstract
Karyopherin beta 1 (Kpnβ1) is the principal nuclear importer of cargo proteins and plays a role in many cellular processes. Its expression is upregulated in cancer and essential for cancer cell viability, thus the identification of its binding partners might help in the discovery of anti-cancer therapeutic targets and cancer biomarkers. Herein, we applied immunoprecipitation coupled to mass spectrometry (IP-MS) to identify Kpnβ1 binding partners in normal and cancer cells. IP-MS identified 100 potential Kpnβ1 binding partners in non-cancer hTERT-RPE1, 179 in HeLa cervical cancer, 147 in WHCO5 oesophageal cancer and 176 in KYSE30 oesophageal cancer cells, including expected and novel interaction partners. 38 binding proteins were identified in all cell lines, with the majority involved in RNA metabolism. 18 binding proteins were unique to the cancer cells, with many involved in protein translation. Western blot analysis validated the interaction of known and novel binding partners with Kpnβ1 and revealed enriched interactions between Kpnβ1 and select proteins in cancer cells, including proteins involved in cancer development, such as Kpnα2, Ran, CRM1, CCAR1 and FUBP1. Together, this study shows that Kpnβ1 interacts with numerous proteins, and its enhanced interaction with certain proteins in cancer cells likely contributes to the cancer state.
Collapse
Affiliation(s)
- Michael O. Okpara
- grid.7836.a0000 0004 1937 1151Division of Medical Biochemistry and Structural Biology, University of Cape Town, Cape Town, South Africa
| | - Clemens Hermann
- grid.7836.a0000 0004 1937 1151Division of Chemical and Systems Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Pauline J. van der Watt
- grid.7836.a0000 0004 1937 1151Division of Medical Biochemistry and Structural Biology, University of Cape Town, Cape Town, South Africa ,grid.7836.a0000 0004 1937 1151Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Shaun Garnett
- grid.7836.a0000 0004 1937 1151Division of Chemical and Systems Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jonathan M. Blackburn
- grid.7836.a0000 0004 1937 1151Division of Chemical and Systems Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa ,grid.7836.a0000 0004 1937 1151Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Virna D. Leaner
- grid.7836.a0000 0004 1937 1151Division of Medical Biochemistry and Structural Biology, University of Cape Town, Cape Town, South Africa ,grid.7836.a0000 0004 1937 1151SAMRC Gynaecology Cancer Research Centre, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
4
|
Damizia M, Altieri L, Lavia P. Non-transport roles of nuclear import receptors: In need of the right balance. Front Cell Dev Biol 2022; 10:1041938. [PMID: 36438555 PMCID: PMC9686011 DOI: 10.3389/fcell.2022.1041938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 10/21/2022] [Indexed: 11/12/2023] Open
Abstract
Nuclear import receptors ensure the recognition and transport of proteins across the nuclear envelope into the nucleus. In addition, as diverse processes as mitosis, post-translational modifications at mitotic exit, ciliogenesis, and phase separation, all share a common need for regulation by nuclear import receptors - particularly importin beta-1 and importin beta-2/transportin - independent on nuclear import. In particular, 1) nuclear import receptors regulate the mitotic spindle after nuclear envelope breakdown, 2) they shield cargoes from unscheduled ubiquitination, regulating their timely proteolysis; 3) they regulate ciliary factors, crucial to cell communications and tissue architecture during development; and 4) they prevent phase separation of toxic proteins aggregates in neurons. The balance of nuclear import receptors to cargoes is critical in all these processes, albeit in opposite directions: overexpression of import receptors, as often found in cancer, inhibits cargoes and impairs downstream processes, motivating the therapeutic design of specific inhibitors. On the contrary, elevated expression is beneficial in neuronal contexts, where nuclear import receptors are regarded as potential therapeutic tools in counteracting the formation of aggregates that may cause neurodegeneration. This paradox demonstrates the amplitude of nuclear import receptors-dependent functions in different contexts and adds complexity in considering their therapeutic implications.
Collapse
Affiliation(s)
- Michela Damizia
- Department of Cellular, Computational and Integrated Biology (CIBIO), University of Trento, Trento, Italy
| | - Ludovica Altieri
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Sapienza University of Rome, Rome, Italy
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Rome, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Sapienza University of Rome, Rome, Italy
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Rome, Italy
| |
Collapse
|
5
|
Role of ubiquitin-protein ligase UBR5 in the disassembly of mitotic checkpoint complexes. Proc Natl Acad Sci U S A 2022; 119:2121478119. [PMID: 35217622 PMCID: PMC8892521 DOI: 10.1073/pnas.2121478119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2022] [Indexed: 11/18/2022] Open
Abstract
The mitotic checkpoint system is essential for the prevention of mistakes in the segregation of chromosomes in mitosis. As long as chromosomes are not attached correctly to the mitotic spindle, a mitotic checkpoint complex (MCC) is assembled and inhibits the action of ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome) to initiate anaphase. When the checkpoint is turned off, MCC is disassembled, allowing anaphase initiation. The mechanisms of MCC disassembly have been studied, but the regulation of this process remained obscure. We found that a second ubiquitin ligase, UBR5 (ubiquitin-protein ligase N-recognin 5), ubiquitylates MCC components and stimulates the disassembly of MCC from APC/C, as well as the dissociation of a subcomplex of MCC. The mitotic (or spindle assembly) checkpoint system ensures accurate chromosome segregation in mitosis by preventing the onset of anaphase until correct bipolar attachment of sister chromosomes to the mitotic spindle is attained. It acts by promoting the assembly of a mitotic checkpoint complex (MCC), composed of mitotic checkpoint proteins BubR1, Bub3, Mad2, and Cdc20. MCC binds to and inhibits the action of ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome), which targets for degradation regulators of anaphase initiation. When the checkpoint system is satisfied, MCCs are disassembled, allowing the recovery of APC/C activity and initiation of anaphase. Many of the pathways of the disassembly of the different MCCs have been elucidated, but the mode of their regulation remained unknown. We find that UBR5 (ubiquitin-protein ligase N-recognin 5) is associated with the APC/C*MCC complex immunopurified from extracts of nocodazole-arrested HeLa cells. UBR5 binds to mitotic checkpoint proteins BubR1, Bub3, and Cdc20 and promotes their polyubiquitylation in vitro. The dissociation of a Bub3*BubR1 subcomplex of MCC is stimulated by UBR5-dependent ubiquitylation, as suggested by observations that this process in mitotic extracts requires UBR5 and α−β bond hydrolysis of adenosine triphosphate. Furthermore, a system reconstituted from purified recombinant components carries out UBR5- and ubiquitylation-dependent dissociation of Bub3*BubR1. Immunodepletion of UBR5 from mitotic extracts slows down the release of MCC components from APC/C and prolongs the lag period in the recovery of APC/C activity in the exit from mitotic checkpoint arrest. We suggest that UBR5 may be involved in the regulation of the inactivation of the mitotic checkpoint.
Collapse
|
6
|
UBR5 HECT domain mutations identified in mantle cell lymphoma control maturation of B cells. Blood 2021; 136:299-312. [PMID: 32325489 DOI: 10.1182/blood.2019002102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 04/03/2020] [Indexed: 12/16/2022] Open
Abstract
Coordination of a number of molecular mechanisms including transcription, alternative splicing, and class switch recombination are required to facilitate development, activation, and survival of B cells. Disruption of these pathways can result in malignant transformation. Recently, next-generation sequencing has identified a number of novel mutations in mantle cell lymphoma (MCL) patients including mutations in the ubiquitin E3 ligase UBR5. Approximately 18% of MCL patients were found to have mutations in UBR5, with the majority of mutations within the HECT domain of the protein that can accept and transfer ubiquitin molecules to the substrate. Determining if UBR5 controls the maturation of B cells is important to fully understand malignant transformation to MCL. To elucidate the role of UBR5 in B-cell maturation and activation, we generated a conditional mutant disrupting UBR5's C-terminal HECT domain. Loss of the UBR5 HECT domain leads to a block in maturation of B cells in the spleen and upregulation of proteins associated with messenger RNA splicing via the spliceosome. Our studies reveal a novel role of UBR5 in B-cell maturation by stabilization of spliceosome components during B-cell development and suggests UBR5 mutations play a role in MCL transformation.
Collapse
|
7
|
Omta WA, van Heesbeen RG, Shen I, de Nobel J, Robers D, van der Velden LM, Medema RH, Siebes APJM, Feelders AJ, Brinkkemper S, Klumperman JS, Spruit MR, Brinkhuis MJS, Egan DA. Combining Supervised and Unsupervised Machine Learning Methods for Phenotypic Functional Genomics Screening. SLAS DISCOVERY 2020; 25:655-664. [PMID: 32400262 DOI: 10.1177/2472555220919345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
There has been an increase in the use of machine learning and artificial intelligence (AI) for the analysis of image-based cellular screens. The accuracy of these analyses, however, is greatly dependent on the quality of the training sets used for building the machine learning models. We propose that unsupervised exploratory methods should first be applied to the data set to gain a better insight into the quality of the data. This improves the selection and labeling of data for creating training sets before the application of machine learning. We demonstrate this using a high-content genome-wide small interfering RNA screen. We perform an unsupervised exploratory data analysis to facilitate the identification of four robust phenotypes, which we subsequently use as a training set for building a high-quality random forest machine learning model to differentiate four phenotypes with an accuracy of 91.1% and a kappa of 0.85. Our approach enhanced our ability to extract new knowledge from the screen when compared with the use of unsupervised methods alone.
Collapse
Affiliation(s)
- Wienand A Omta
- Department of Cell Biology, Centre for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands.,Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands.,Core Life Analytics B.V., Utrecht, The Netherlands
| | - Roy G van Heesbeen
- Department of Cell Biology, NKI-AVL, Amsterdam, Noord-Holland, The Netherlands
| | - Ian Shen
- Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jacob de Nobel
- Department of Cell Biology, Centre for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
| | - Desmond Robers
- Department of Cell Biology, Centre for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
| | - Lieke M van der Velden
- Department of Cell Biology, Centre for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
| | - René H Medema
- Department of Cell Biology, NKI-AVL, Amsterdam, Noord-Holland, The Netherlands
| | - Arno P J M Siebes
- Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands
| | - Ad J Feelders
- Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands
| | - Sjaak Brinkkemper
- Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands
| | - Judith S Klumperman
- Department of Cell Biology, Centre for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
| | - Marco René Spruit
- Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands
| | - Matthieu J S Brinkhuis
- Department of Information and Computing Sciences, Utrecht University, Utrecht, The Netherlands
| | - David A Egan
- Core Life Analytics B.V., Utrecht, The Netherlands
| |
Collapse
|
8
|
Verrico A, Rovella P, Di Francesco L, Damizia M, Staid DS, Le Pera L, Schininà ME, Lavia P. Importin-β/karyopherin-β1 modulates mitotic microtubule function and taxane sensitivity in cancer cells via its nucleoporin-binding region. Oncogene 2019; 39:454-468. [PMID: 31492900 DOI: 10.1038/s41388-019-0989-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 02/27/2019] [Accepted: 04/25/2019] [Indexed: 12/11/2022]
Abstract
The nuclear transport receptor importin-β/karyopherin-β1 is overexpressed in cancers that display genomic instability. It is regarded as a promising cancer target and inhibitors are being developed. In addition to its role in nucleo-cytoplasmic transport, importin-β regulates mitosis, but the programmes and pathways in which it operates are defined only in part. To unravel importin-β's mitotic functions we have developed cell lines expressing either wild-type or a mutant importin-β form in characterised residues required for nucleoporin binding. Both forms similarly disrupted spindle pole organisation, while only wild-type importin-β affected microtubule plus-end function and microtubule stability. A proteome-wide search for differential interactors identified a set of spindle regulators sensitive to mutations in the nucleoporin-binding region. Among those, HURP (hepatoma up-regulated protein) is an importin-β interactor and a microtubule-stabilising factor. We found that induction of wild type, but not mutant importin-β, under the same conditions that destabilise mitotic microtubules, delocalised HURP, indicating that the spatial distribution of HURP along the spindle requires importin-β's nucleoporin-binding residues. Concomitantly, importin-β overexpression sensitises cells to taxanes and synergistically increases mitotic cell death. Thus, the nucleoporin-binding domain is dispensable for importin-β function in spindle pole organisation, but regulates microtubule stability, at least in part via HURP, and renders cells vulnerable to certain microtubule-targeting drugs.
Collapse
Affiliation(s)
- Annalisa Verrico
- Institute of Molecular Biology and Pathology (IBPM), CNR Consiglio Nazionale delle Ricerche, 00185, Rome, Italy.,Institut Jacques Monod, UMR7592 CNRS-Université Paris Diderot, Sorbonne Paris Cité, F-75205, Paris, France
| | - Paola Rovella
- Institute of Molecular Biology and Pathology (IBPM), CNR Consiglio Nazionale delle Ricerche, 00185, Rome, Italy
| | - Laura Di Francesco
- Department of Biochemical Sciences "Alessandro Rossi-Fanelli", Sapienza University of Rome, 00185, Rome, Italy
| | - Michela Damizia
- Institute of Molecular Biology and Pathology (IBPM), CNR Consiglio Nazionale delle Ricerche, 00185, Rome, Italy.,Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185, Rome, Italy
| | - David Sasah Staid
- Institute of Molecular Biology and Pathology (IBPM), CNR Consiglio Nazionale delle Ricerche, 00185, Rome, Italy.,Department of Biochemical Sciences "Alessandro Rossi-Fanelli", Sapienza University of Rome, 00185, Rome, Italy
| | - Loredana Le Pera
- Institute of Molecular Biology and Pathology (IBPM), CNR Consiglio Nazionale delle Ricerche, 00185, Rome, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), CNR Consiglio Nazionale delle Ricerche, 70126, Bari, Italy
| | - M Eugenia Schininà
- Department of Biochemical Sciences "Alessandro Rossi-Fanelli", Sapienza University of Rome, 00185, Rome, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology (IBPM), CNR Consiglio Nazionale delle Ricerche, 00185, Rome, Italy. .,Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185, Rome, Italy.
| |
Collapse
|
9
|
Tiwary AK, Zheng Y. Protein phase separation in mitosis. Curr Opin Cell Biol 2019; 60:92-98. [PMID: 31176175 DOI: 10.1016/j.ceb.2019.04.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 04/26/2019] [Indexed: 01/11/2023]
Abstract
Through phase separation, some proteins form liquid-like condensates or droplets which can flow, fuse, and even deform when pressure is applied. In some cases, the condensates 'mature' to form gel or solid-like structure. Recent studies suggest that the liquid-like condensates form the structural basis for several membrane-less subcellular organelles such as stress granules and other subcellular structures. Here, we review and discuss studies that implicate protein phase separation in the function of the spindle apparatus and centrosomes.
Collapse
Affiliation(s)
- Ashish Kumar Tiwary
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, United States
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, United States.
| |
Collapse
|
10
|
Nasa I, Rusin SF, Kettenbach AN, Moorhead GB. Aurora B opposes PP1 function in mitosis by phosphorylating the conserved PP1-binding RVxF motif in PP1 regulatory proteins. Sci Signal 2018; 11:11/530/eaai8669. [PMID: 29764992 DOI: 10.1126/scisignal.aai8669] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Protein phosphatase 1 (PP1) is a highly conserved protein phosphatase that performs most of the serine- and threonine-dephosphorylation reactions in eukaryotes and opposes the actions of a diverse set of serine and threonine (Ser-Thr) protein kinases. PP1 gains substrate specificity through binding to a large number (>200) of regulatory proteins that control PP1 localization, activity, and interactions with substrates. PP1 recognizes the well-characterized RVxF binding motif that is present in many of these regulatory proteins, thus generating a multitude of distinct PP1 holoenzymes. We showed that a subset of the RVxF binding motifs, in which x is a phosphorylatable amino acid (RV[S/T]F), was phosphorylated specifically during mitosis and that this phosphorylation event abrogated the interaction of PP1 with the regulatory protein. We determined that this phosphorylation was primarily governed by the mitotic protein kinase Aurora B and that high phosphorylation site stoichiometry of these sites maintained the phosphorylation of PP1 substrates during mitosis by disrupting the assembly of PP1 holoenzymes. We generated an antibody that recognizes the phosphorylated form of the RV[S/T]F motif (RVp[S/T]F) and used it to identify known PP1 regulatory proteins (KNL1, CDCA2, and RIF1) and multiple proteins that could potentially act as PP1 binding partners (UBR5, ASPM, SEH1, and ELYS) governed by this mechanism. Together, these data suggest a general regulatory mechanism by which the coordinated activities of Aurora B and PP1 control mitotic progression.
Collapse
Affiliation(s)
- Isha Nasa
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Scott F Rusin
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. .,Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Greg B Moorhead
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
| |
Collapse
|
11
|
Di Francesco L, Verrico A, Asteriti IA, Rovella P, Cirigliano P, Guarguaglini G, Schininà ME, Lavia P. Visualization of human karyopherin beta-1/importin beta-1 interactions with protein partners in mitotic cells by co-immunoprecipitation and proximity ligation assays. Sci Rep 2018; 8:1850. [PMID: 29382863 PMCID: PMC5789818 DOI: 10.1038/s41598-018-19351-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 12/29/2017] [Indexed: 12/29/2022] Open
Abstract
Karyopherin beta-1/Importin beta-1 is a conserved nuclear transport receptor, acting in protein nuclear import in interphase and as a global regulator of mitosis. These pleiotropic functions reflect its ability to interact with, and regulate, different pathways during the cell cycle, operating as a major effector of the GTPase RAN. Importin beta-1 is overexpressed in cancers characterized by high genetic instability, an observation that highlights the importance of identifying its partners in mitosis. Here we present the first comprehensive profile of importin beta-1 interactors from human mitotic cells. By combining co-immunoprecipitation and proteome-wide mass spectrometry analysis of synchronized cell extracts, we identified expected (e.g., RAN and SUMO pathway factors) and novel mitotic interactors of importin beta-1, many with RNA-binding ability, that had not been previously associated with importin beta-1. These data complement interactomic studies of interphase transport pathways. We further developed automated proximity ligation assay (PLA) protocols to validate selected interactors. We succeeded in obtaining spatial and temporal resolution of genuine importin beta-1 interactions, which were visualized and localized in situ in intact mitotic cells. Further developments of PLA protocols will be helpful to dissect importin beta-1-orchestrated pathways during mitosis.
Collapse
Affiliation(s)
- Laura Di Francesco
- Dipartimento di Scienze Biochimiche, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.,Unit of Human Microbiome, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy
| | - Annalisa Verrico
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | - Italia Anna Asteriti
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | - Paola Rovella
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | | | - Giulia Guarguaglini
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | - Maria Eugenia Schininà
- Dipartimento di Scienze Biochimiche, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy.
| |
Collapse
|
12
|
Huang Y, Li T, Ems-McClung SC, Walczak CE, Prigent C, Zhu X, Zhang X, Zheng Y. Aurora A activation in mitosis promoted by BuGZ. J Cell Biol 2017; 217:107-116. [PMID: 29074706 PMCID: PMC5748987 DOI: 10.1083/jcb.201706103] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 09/22/2017] [Accepted: 09/27/2017] [Indexed: 12/25/2022] Open
Abstract
Mitotic spindle component BuGZ is known to undergo phase separation. Huang et al. show that BuGZ promotes Aurora A phosphorylation and activation and that this is inhibited when BuGZ phase separation is disrupted. Protein phase separation or coacervation has emerged as a potential mechanism to regulate biological functions. We have shown that coacervation of a mostly unstructured protein, BuGZ, promotes assembly of spindle and its matrix. BuGZ in the spindle matrix binds and concentrates tubulin to promote microtubule (MT) assembly. It remains unclear, however, whether BuGZ could regulate additional proteins to promote spindle assembly. In this study, we report that BuGZ promotes Aurora A (AurA) activation in vitro. Depletion of BuGZ in cells reduces the amount of phosphorylated AurA on spindle MTs. BuGZ also enhances MCAK phosphorylation. The two zinc fingers in BuGZ directly bind to the kinase domain of AurA, which allows AurA to incorporate into the coacervates formed by BuGZ in vitro. Importantly, mutant BuGZ that disrupts the coacervation activity in vitro fails to promote AurA phosphorylation in Xenopus laevis egg extracts. These results suggest that BuGZ coacervation promotes AurA activation in mitosis.
Collapse
Affiliation(s)
- Yuejia Huang
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD
| | - Teng Li
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD.,Institute of Basic Medical Sciences, National Center of Biomedical Analysis, Beijing, China
| | | | | | - Claude Prigent
- Institut de Génétique et Développement de Rennes, Equipe laboratoryélisée Ligue Nationale Contre la Cancer 2014-2017, Centre National de la Recherche Scientifique, Université Rennes 1, Rennes, France
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xuemin Zhang
- Institute of Basic Medical Sciences, National Center of Biomedical Analysis, Beijing, China
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD
| |
Collapse
|
13
|
Carvalhal S, Stevense M, Koehler K, Naumann R, Huebner A, Jessberger R, Griffis ER. ALADIN is required for the production of fertile mouse oocytes. Mol Biol Cell 2017; 28:2470-2478. [PMID: 28768824 PMCID: PMC5597320 DOI: 10.1091/mbc.e16-03-0158] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/27/2017] [Accepted: 07/27/2017] [Indexed: 11/11/2022] Open
Abstract
The nucleoporin ALADIN is required for multiple stages of oocyte maturation and for supporting embryonic divisions postfertilization. Asymmetric cell divisions depend on the precise placement of the spindle apparatus. In mammalian oocytes, spindles assemble close to the cell’s center, but chromosome segregation takes place at the cell periphery where half of the chromosomes are expelled into small, nondeveloping polar bodies at anaphase. By dividing so asymmetrically, most of the cytoplasmic content within the oocyte is preserved, which is critical for successful fertilization and early development. Recently we determined that the nucleoporin ALADIN participates in spindle assembly in somatic cells, and we have also shown that female mice homozygously null for ALADIN are sterile. In this study we show that this protein is involved in specific meiotic stages, including meiotic resumption, spindle assembly, and spindle positioning. In the absence of ALADIN, polar body extrusion is compromised due to problems in spindle orientation and anchoring at the first meiotic anaphase. ALADIN null oocytes that mature far enough to be fertilized in vitro are unable to support embryonic development beyond the two-cell stage. Overall, we find that ALADIN is critical for oocyte maturation and appears to be far more essential for this process than for somatic cell divisions.
Collapse
Affiliation(s)
- Sara Carvalhal
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Michelle Stevense
- Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Katrin Koehler
- Department of Paediatrics, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Ronald Naumann
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Angela Huebner
- Department of Paediatrics, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Rolf Jessberger
- Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Eric R Griffis
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| |
Collapse
|
14
|
BMI1-UBR5 axis regulates transcriptional repression at damaged chromatin. Proc Natl Acad Sci U S A 2016; 113:11243-11248. [PMID: 27647897 DOI: 10.1073/pnas.1610735113] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BMI1 is a component of the Polycomb Repressive Complex 1 (PRC1), which plays a key role in maintaining epigenetic silencing during development. BMI1 also participates in gene silencing during DNA damage response, but the precise downstream function of BMI1 in gene silencing is unclear. Here we identified the UBR5 E3 ligase as a downstream factor of BMI1. We found that UBR5 forms damage-inducible nuclear foci in a manner dependent on the PRC1 components BMI1, RNF1 (RING1a), and RNF2 (RING1b). Whereas transcription is repressed at UV-induced lesions on chromatin, depletion of the PRC1 members or UBR5 alone derepressed transcription elongation at these sites, suggesting that UBR5 functions in a linear pathway with PRC1 in inducing gene silencing at lesions. Mass spectrometry (MS) analysis revealed that UBR5 associates with BMI1 as well as FACT components SPT16 and SSRP1. We found that UBR5 localizes to the UV-induced lesions along with SPT16. We show that UBR5 ubiquitinates SPT16, and depletion of UBR5 or BMI1 leads to an enlargement of SPT16 foci size at UV lesions, suggesting that UBR5 and BMI1 repress SPT16 enrichment at the damaged sites. Consistently, depletion of the FACT components effectively reversed the transcriptional derepression incurred in the UBR5 and BMI1 KO cells. Finally, UBR5 and BMI1 KO cells are hypersensitive to UV, which supports the notion that faulty RNA synthesis at damaged sites is harmful to the cell fitness. Altogether, these results suggest that BMI1 and UBR5 repress the polymerase II (Pol II)-mediated transcription at damaged sites, by negatively regulating the FACT-dependent Pol II elongation.
Collapse
|
15
|
Safdar K, Gu A, Xu X, Au V, Taylor J, Flibotte S, Moerman DG, Maine EM. UBR-5, a Conserved HECT-Type E3 Ubiquitin Ligase, Negatively Regulates Notch-Type Signaling in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2016; 6:2125-34. [PMID: 27185398 PMCID: PMC4938665 DOI: 10.1534/g3.116.027805] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/09/2016] [Indexed: 12/17/2022]
Abstract
Notch-type signaling mediates cell-cell interactions important for animal development. In humans, reduced or inappropriate Notch signaling activity is associated with various developmental defects and disease states, including cancers. Caenorhabditis elegans expresses two Notch-type receptors, GLP-1 and LIN-12. GLP-1 mediates several cell-signaling events in the embryo and promotes germline proliferation in the developing and adult gonad. LIN-12 acts redundantly with GLP-1 in certain inductive events in the embryo and mediates several cell-cell interactions during larval development. Recovery of genetic suppressors and enhancers of glp-1 or lin-12 loss- or gain-of-function mutations has identified numerous regulators of GLP-1 and LIN-12 signaling activity. Here, we report the molecular identification of sog-1, a gene identified in screens for recessive suppressors of conditional glp-1 loss-of-function mutations. The sog-1 gene encodes UBR-5, the sole C. elegans member of the UBR5/Hyd family of HECT-type E3 ubiquitin ligases. Molecular and genetic analyses indicate that the loss of ubr-5 function suppresses defects caused by reduced signaling via GLP-1 or LIN-12. In contrast, ubr-5 mutations do not suppress embryonic or larval lethality associated with mutations in a downstream transcription factor, LAG-1. In the gonad, ubr-5 acts in the receiving cells (germ cells) to limit GLP-1 signaling activity. SEL-10 is the F-box component of SCF(SEL-10) E3 ubiquitin-ligase complex that promotes turnover of Notch intracellular domain. UBR-5 acts redundantly with SEL-10 to limit Notch signaling in certain tissues. We hypothesize that UBR-5 activity limits Notch-type signaling by promoting turnover of receptor or limiting its interaction with pathway components.
Collapse
Affiliation(s)
- Komal Safdar
- Department of Biology, Syracuse University, New York 13244
| | - Anniya Gu
- Department of Biology, Syracuse University, New York 13244
| | - Xia Xu
- Department of Biology, Syracuse University, New York 13244
| | - Vinci Au
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Jon Taylor
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Stephane Flibotte
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Donald G Moerman
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | | |
Collapse
|