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Shergalis AG, Marin VL, Rhee DY, Senaweera S, McCloud RL, Ronau JA, Hutchins CW, McLoughlin S, Woller KR, Warder SE, Vasudevan A, Reitsma JM. CRISPR Screen Reveals BRD2/4 Molecular Glue-like Degrader via Recruitment of DCAF16. ACS Chem Biol 2023; 18:331-339. [PMID: 36656921 DOI: 10.1021/acschembio.2c00747] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Molecular glues (MGs) are monovalent small molecules that induce an interaction between proteins (native or non-native partners) by altering the protein-protein interaction (PPI) interface toward a higher-affinity state. Enhancing the PPI between a protein and E3 ubiquitin ligase can lead to degradation of the partnering protein. Over the past decade, retrospective studies of clinical drugs identified that immunomodulatory drugs (e.g., thalidomide and analogues) and indisulam exhibit a molecular glue effect by driving the interaction between non-native substrates to CRBN and DCAF15 ligases, respectively. Ensuing reports of phenotypic screens focused on MG discovery have suggested that these molecules may be more common than initially anticipated. However, prospective discovery of MGs remains challenging. Thus, expanding the repertoire of MGs will enhance our understanding of principles for prospective design. Herein, we report the results of a CRISPR/Cas9 knockout screen of over 1000 ligases and ubiquitin proteasome system components in a BRD4 degradation assay with a JQ1-based monovalent degrader, compound 1a. We identified DCAF16, a substrate recognition component of the Cul4 ligase complex, as essential for compound activity, and we demonstrate that compound 1a drives the interaction between DCAF16 and BRD2/4 to promote target degradation. Taken together, our data suggest that compound 1a functions as an MG degrader between BRD2/4 and DCAF16 and provides a foundation for further mechanistic dissection to advance prospective MG discovery.
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Affiliation(s)
- Andrea G Shergalis
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Violeta L Marin
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - David Y Rhee
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Sameera Senaweera
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Rebecca L McCloud
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Judith A Ronau
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Charles W Hutchins
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Shaun McLoughlin
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Kevin R Woller
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Scott E Warder
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Anil Vasudevan
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
| | - Justin M Reitsma
- Drug Discovery Science & Technology, AbbVie Inc, North Chicago, Illinois 60064, United States
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2
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Yin C, Lui ESW, Jiang T, Qi RZ. Proteolysis of γ-tubulin small complex proteins is mediated by the ubiquitin-proteasome system. FEBS Lett 2021; 595:1987-1996. [PMID: 34107052 DOI: 10.1002/1873-3468.14146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/23/2021] [Accepted: 06/02/2021] [Indexed: 11/12/2022]
Abstract
Microtubule nucleation is mainly mediated by the γ-tubulin ring complex (γTuRC), whose core components are γ-tubulin and γ-tubulin complex proteins GCP2-6. A substantial fraction of γ-tubulin also exists with GCP2 and GCP3 in a tetramer called the γ-tubulin small complex (γTuSC). To date, the mechanisms underlying the turnover of γ-tubulin and GCPs have remained unclear. Here, we show that γ-tubulin, GCP2, and GCP3 are proteolyzed by the ubiquitin-proteasome system, and we identify cullin 1, cullin 4A, and cullin 4B as the E3 ligases that mediate the ubiquitination and, consequently, the degradation of γ-tubulin. Notably, we found that γTuSC disassembly promotes the degradation of γ-tubulin, GCP2, and GCP3, which indicates a role for γTuSCs in the stabilization of its components.
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Affiliation(s)
- Can Yin
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
| | - Edna S W Lui
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
| | - Taolue Jiang
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
| | - Robert Z Qi
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
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3
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Asmar AJ, Beck DB, Werner A. Control of craniofacial and brain development by Cullin3-RING ubiquitin ligases: Lessons from human disease genetics. Exp Cell Res 2020; 396:112300. [PMID: 32986984 PMCID: PMC10627151 DOI: 10.1016/j.yexcr.2020.112300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/16/2020] [Accepted: 09/20/2020] [Indexed: 12/19/2022]
Abstract
Metazoan development relies on intricate cell differentiation, communication, and migration pathways, which ensure proper formation of specialized cell types, tissues, and organs. These pathways are crucially controlled by ubiquitylation, a reversible post-translational modification that regulates the stability, activity, localization, or interaction landscape of substrate proteins. Specificity of ubiquitylation is ensured by E3 ligases, which bind substrates and co-operate with E1 and E2 enzymes to mediate ubiquitin transfer. Cullin3-RING ligases (CRL3s) are a large class of multi-subunit E3s that have emerged as important regulators of cell differentiation and development. In particular, recent evidence from human disease genetics, animal models, and mechanistic studies have established their involvement in the control of craniofacial and brain development. Here, we summarize regulatory principles of CRL3 assembly, substrate recruitment, and ubiquitylation that allow this class of E3s to fulfill their manifold functions in development. We further review our current mechanistic understanding of how specific CRL3 complexes orchestrate neuroectodermal differentiation and highlight diseases associated with their dysregulation. Based on evidence from human disease genetics, we propose that other unknown CRL3 complexes must help coordinate craniofacial and brain development and discuss how combining emerging strategies from the field of disease gene discovery with biochemical and human pluripotent stem cell approaches will likely facilitate their identification.
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Affiliation(s)
- Anthony J Asmar
- Stem Cell Biochemistry Unit, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - David B Beck
- Stem Cell Biochemistry Unit, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA; Metabolic, Cardiovascular and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Achim Werner
- Stem Cell Biochemistry Unit, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA.
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4
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Keller M, Hu Y, Mesihovic A, Fragkostefanakis S, Schleiff E, Simm S. Alternative splicing in tomato pollen in response to heat stress. DNA Res 2018; 24:205-217. [PMID: 28025318 PMCID: PMC5397606 DOI: 10.1093/dnares/dsw051] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 10/26/2016] [Indexed: 01/08/2023] Open
Abstract
Alternative splicing (AS) is a key control mechanism influencing signal response cascades in different developmental stages and under stress conditions. In this study, we examined heat stress (HS)-induced AS in the heat sensitive pollen tissue of two tomato cultivars. To obtain the entire spectrum of HS-related AS, samples taken directly after HS and after recovery were combined and analysed by RNA-seq. For nearly 9,200 genes per cultivar, we observed at least one AS event under HS. In comparison to control, for one cultivar we observed 76% more genes with intron retention (IR) or exon skipping (ES) under HS. Furthermore, 2,343 genes had at least one transcript with IR or ES accumulated under HS in both cultivars. These genes are involved in biological processes like protein folding, gene expression and heat response. Transcriptome assembly of these genes revealed that most of the alternative spliced transcripts possess truncated coding sequences resulting in partial or total loss of functional domains. Moreover, 141 HS specific and 22 HS repressed transcripts were identified. Further on, we propose AS as layer of stress response regulating constitutively expressed genes under HS by isoform abundance.
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Affiliation(s)
- Mario Keller
- Department of Biosciences, Molecular Cell Biology of Plants
| | - Yangjie Hu
- Department of Biosciences, Molecular Cell Biology of Plants
| | | | | | - Enrico Schleiff
- Department of Biosciences, Molecular Cell Biology of Plants.,Cluster of Excellence Frankfurt.,Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University, D-60438 Frankfurt am Main, Germany
| | - Stefan Simm
- Department of Biosciences, Molecular Cell Biology of Plants.,Cluster of Excellence Frankfurt
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5
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Strand NS, Allen JM, Ghulam M, Taylor MR, Munday RK, Carrillo M, Movsesyan A, Zayas RM. Dissecting the function of Cullin-RING ubiquitin ligase complex genes in planarian regeneration. Dev Biol 2018; 433:210-217. [PMID: 29291974 DOI: 10.1016/j.ydbio.2017.10.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/25/2017] [Accepted: 10/11/2017] [Indexed: 12/26/2022]
Abstract
The ubiquitin system plays a role in nearly every aspect of eukaryotic cell biology. The enzymes responsible for transferring ubiquitin onto specific substrates are the E3 ubiquitin ligases, a large and diverse family of proteins, for which biological roles and target substrates remain largely undefined. Studies using model organisms indicate that ubiquitin signaling mediates key steps in developmental processes and tissue regeneration. Here, we used the freshwater planarian, Schmidtea mediterranea, to investigate the role of Cullin-RING ubiquitin ligase (CRL) complexes in stem cell regulation during regeneration. We identified six S. mediterranea cullin genes, and used RNAi to uncover roles for homologs of Cullin-1, -3 and -4 in planarian regeneration. The cullin-1 RNAi phenotype included defects in blastema formation, organ regeneration, lesions, and lysis. To further investigate the function of cullin-1-mediated cellular processes in planarians, we examined genes encoding the adaptor protein Skp1 and F-box substrate-recognition proteins that are predicted to partner with Cullin-1. RNAi against skp1 resulted in phenotypes similar to cullin-1 RNAi, and an RNAi screen of the F-box genes identified 19 genes that recapitulated aspects of cullin-1 RNAi, including ones that in mammals are involved in stem cell regulation and cancer biology. Our data provides evidence that CRLs play discrete roles in regenerative processes and provide a platform to investigate how CRLs regulate stem cells in vivo.
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Affiliation(s)
- Nicholas S Strand
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - John M Allen
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Mahjoobah Ghulam
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Matthew R Taylor
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Roma K Munday
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Melissa Carrillo
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Artem Movsesyan
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Ricardo M Zayas
- Department of Biology, San Diego State University, San Diego, CA 92182, USA.
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6
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Cell-fate determination by ubiquitin-dependent regulation of translation. Nature 2015; 525:523-7. [PMID: 26399832 PMCID: PMC4602398 DOI: 10.1038/nature14978] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/24/2015] [Indexed: 02/06/2023]
Abstract
Metazoan development depends on accurate execution of differentiation programs that allow pluripotent stem cells to adopt specific fates 1. Differentiation requires changes to chromatin architecture and transcriptional networks, yet whether other regulatory events support cell fate determination is less well understood. Here, we have identified the vertebrate-specific ubiquitin ligase CUL3KBTBD8 as an essential regulator of neural crest specification. CUL3KBTBD8 monoubiquitylates NOLC1 and its paralog TCOF1, whose mutation underlies the neurocristopathy Treacher Collins Syndrome 2,3. Ubiquitylation drives formation of a TCOF1-NOLC1 platform that connects RNA polymerase I with ribosome modification enzymes and remodels the translational program of differentiating cells in favor of neural crest specification. We conclude that ubiquitin-dependent regulation of translation is an important feature of cell fate determination.
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7
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Mayilswami S, Krishnan K, Megharaj M, Naidu R. Chronic PFOS exposure alters the expression of neuronal development-related human homologues in Eisenia fetida. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 110:288-297. [PMID: 25285771 DOI: 10.1016/j.ecoenv.2014.09.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/13/2014] [Accepted: 09/15/2014] [Indexed: 06/03/2023]
Abstract
PFOS is a toxic, persistent environmental pollutant which is widespread worldwide. PFOS contamination has entered the food chain and is interfering with normal development in man and is neurotoxic, hepatotoxic and tumorigenic. The earthworm, Eisenia fetida is one of the organisms which can help to diagnose soil health and contamination at lower levels in the food chain. Studying the chronic effects of sub-lethal PFOS exposure in such an organism is therefore appropriate. As PFOS bioaccumulates and is not easily biodegraded, it is biomagnified up the food chain. Gene expression studies will give us information to develop biomarkers for early diagnosis of soil contamination, well before this contaminant passes up the food chain. We have carried out mRNA sequencing of control and chronically PFOS exposed E. fetida and reconstructed the transcripts in silico and identified the differentially expressed genes. Our findings suggest that PFOS up/down regulates neurodegenerative-related human homologues and can cause neuronal damage in E. fetida. This information will help to understand the links between neurodegenerative disorders and environmental pollutants such as PFOS. Furthermore, these up/down regulated genes can be used as biomarkers to detect a sub-lethal presence of PFOS in soil. Neuronal calcium sensor-2, nucleoside diphosphate kinase, polyadenylate-binding protein-1 and mitochondrial Pyruvate dehydrogenase protein-X component, could be potential biomarkers for sub lethal concentrations of PFOS.
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Affiliation(s)
- Srinithi Mayilswami
- Centre for Environmental Risk Assessment and Remediation, University of South Australia & CRC CARE, Mawson Lakes, Adelaide 5095, SA, Australia
| | - Kannan Krishnan
- Centre for Environmental Risk Assessment and Remediation, University of South Australia & CRC CARE, Mawson Lakes, Adelaide 5095, SA, Australia.
| | - Mallavarapu Megharaj
- Centre for Environmental Risk Assessment and Remediation, University of South Australia & CRC CARE, Mawson Lakes, Adelaide 5095, SA, Australia
| | - Ravi Naidu
- Centre for Environmental Risk Assessment and Remediation, University of South Australia & CRC CARE, Mawson Lakes, Adelaide 5095, SA, Australia
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8
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Wong JJL, Li S, Lim EKH, Wang Y, Wang C, Zhang H, Kirilly D, Wu C, Liou YC, Wang H, Yu F. A Cullin1-based SCF E3 ubiquitin ligase targets the InR/PI3K/TOR pathway to regulate neuronal pruning. PLoS Biol 2013; 11:e1001657. [PMID: 24068890 PMCID: PMC3775723 DOI: 10.1371/journal.pbio.1001657] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 08/08/2013] [Indexed: 11/19/2022] Open
Abstract
Pruning that selectively eliminates unnecessary axons/dendrites is crucial for sculpting the nervous system during development. During Drosophila metamorphosis, dendrite arborization neurons, ddaCs, selectively prune their larval dendrites in response to the steroid hormone ecdysone, whereas mushroom body γ neurons specifically eliminate their axon branches within dorsal and medial lobes. However, it is unknown which E3 ligase directs these two modes of pruning. Here, we identified a conserved SCF E3 ubiquitin ligase that plays a critical role in pruning of both ddaC dendrites and mushroom body γ axons. The SCF E3 ligase consists of four core components Cullin1/Roc1a/SkpA/Slimb and promotes ddaC dendrite pruning downstream of EcR-B1 and Sox14, but independently of Mical. Moreover, we demonstrate that the Cullin1-based E3 ligase facilitates ddaC dendrite pruning primarily through inactivation of the InR/PI3K/TOR pathway. We show that the F-box protein Slimb forms a complex with Akt, an activator of the InR/PI3K/TOR pathway, and promotes Akt ubiquitination. Activation of the InR/PI3K/TOR pathway is sufficient to inhibit ddaC dendrite pruning. Thus, our findings provide a novel link between the E3 ligase and the InR/PI3K/TOR pathway during dendrite pruning.
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Affiliation(s)
- Jack Jing Lin Wong
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
- Graduate School for Integrated Sciences and Engineering, Centre for Life Sciences, National University of Singapore (NUS), Singapore
| | - Song Li
- Graduate School for Integrated Sciences and Engineering, Centre for Life Sciences, National University of Singapore (NUS), Singapore
- Neuroscience and Behavioral Disorder Program, Duke–NUS Graduate Medical School Singapore, Singapore
| | - Edwin Kok Hao Lim
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
| | - Yan Wang
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
| | - Cheng Wang
- Neuroscience and Behavioral Disorder Program, Duke–NUS Graduate Medical School Singapore, Singapore
| | - Heng Zhang
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
| | - Daniel Kirilly
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
| | - Chunlai Wu
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Yih-Cherng Liou
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
- Graduate School for Integrated Sciences and Engineering, Centre for Life Sciences, National University of Singapore (NUS), Singapore
| | - Hongyan Wang
- Graduate School for Integrated Sciences and Engineering, Centre for Life Sciences, National University of Singapore (NUS), Singapore
- Neuroscience and Behavioral Disorder Program, Duke–NUS Graduate Medical School Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Fengwei Yu
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
- Graduate School for Integrated Sciences and Engineering, Centre for Life Sciences, National University of Singapore (NUS), Singapore
- Neuroscience and Behavioral Disorder Program, Duke–NUS Graduate Medical School Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- * E-mail:
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9
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Wiszniak S, Lumb R, Kabbara S, Scherer M, Schwarz Q. Li-gazing at the crest: modulation of the neural crest by the ubiquitin pathway. Int J Biochem Cell Biol 2013; 45:1087-91. [PMID: 23458963 DOI: 10.1016/j.biocel.2013.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/08/2013] [Accepted: 02/22/2013] [Indexed: 10/27/2022]
Abstract
Neural crest cells are a transient population of stem cells that give rise to a diverse range of cell types during embryonic development. Through gain-of-function and loss-of-function studies in several model organisms many key signalling pathways and cell-type specific transcription factors essential for neural crest cell development have been identified. However, the role of post-translational regulation remains largely unexplored. Here we review this cell type with a foray into the known and potential roles of the ubiquitination pathway in key signalling events during neural crest cell development.
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Affiliation(s)
- Sophie Wiszniak
- Centre for Cancer Biology, SA Pathology, Adelaide 5000, Australia
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10
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Suzuki T, Osumi N, Wakamatsu Y. Stabilization of ATF4 protein is required for the regulation of epithelial-mesenchymal transition of the avian neural crest. Dev Biol 2010; 344:658-68. [PMID: 20580702 DOI: 10.1016/j.ydbio.2010.05.492] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Revised: 05/13/2010] [Accepted: 05/16/2010] [Indexed: 12/20/2022]
Abstract
Epithelial-mesenchymal transition (EMT) permits neural crest cells to delaminate from the epithelial ectoderm and to migrate extensively in the embryonic environment. In this study, we have identified ATF4, a basic-leucine-zipper transcription factor, as one of the neural crest EMT regulators. Although ATF4 alone was not sufficient to drive the formation of migratory neural crest cells, ATF4 cooperated with Sox9 to induce neural crest EMT by controlling the expression of cell-cell and cell-extracellular matrix adhesion molecules. This was likely, at least in part, by inducing the expression of Foxd3, which encodes another neural crest transcription factor. We also found that the ATF4 protein level was strictly regulated by proteasomal degradation and p300-mediated stabilization, allowing ATF4 protein to accumulate in the nuclei of neural crest cells undergoing EMT. Thus, our results emphasize the importance of the regulation of protein stability in the neural crest EMT.
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Affiliation(s)
- Takashi Suzuki
- Center for Translational and Advanced Animal Research on Human Diseases, Division of Developmental Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, Miyagi 980-8575, Japan
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11
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Almeida AD, Wise HM, Hindley CJ, Slevin MK, Hartley RS, Philpott A. The F-box protein Cdc4/Fbxw7 is a novel regulator of neural crest development in Xenopus laevis. Neural Dev 2010; 5:1. [PMID: 20047651 PMCID: PMC2819241 DOI: 10.1186/1749-8104-5-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 01/04/2010] [Indexed: 11/13/2022] Open
Abstract
Background The neural crest is a unique population of cells that arise in the vertebrate ectoderm at the neural plate border after which they migrate extensively throughout the embryo, giving rise to a wide range of derivatives. A number of proteins involved in neural crest development have dynamic expression patterns, and it is becoming clear that ubiquitin-mediated protein degradation is partly responsible for this. Results Here we demonstrate a novel role for the F-box protein Cdc4/Fbxw7 in neural crest development. Two isoforms of Xenopus laevis Cdc4 were identified, and designated xCdc4α and xCdc4β. These are highly conserved with vertebrate Cdc4 orthologs, and the Xenopus proteins are functionally equivalent in terms of their ability to degrade Cyclin E, an established vertebrate Cdc4 target. Blocking xCdc4 function specifically inhibited neural crest development at an early stage, prior to expression of c-Myc, Snail2 and Snail. Conclusions We demonstrate that Cdc4, an ubiquitin E3 ligase subunit previously identified as targeting primarily cell cycle regulators for proteolysis, has additional roles in control of formation of the neural crest. Hence, we identify Cdc4 as a protein with separable but complementary functions in control of cell proliferation and differentiation.
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Affiliation(s)
- Alexandra D Almeida
- Department of Oncology, University of Cambridge, Hutchison-MRC Research Centre, Addenbrookes Hospital, Hills Road, Cambridge, CB2 0XZ, UK
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Hong CS, Park BY, Saint-Jeannet JP. Fgf8a induces neural crest indirectly through the activation of Wnt8 in the paraxial mesoderm. Development 2009; 135:3903-10. [PMID: 18997112 DOI: 10.1242/dev.026229] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Two independent signals are necessary for neural crest (NC) induction in Xenopus: a Bmp signal, which must be partially attenuated by Bmp antagonists, and a separate signal mediated by either a canonical Wnt or an Fgf. The mesoderm underlying the NC-forming region has been proposed as a source of this second signal. Wnt8 and Fgf8a are expressed in this tissue around the time of NC induction and are therefore good candidate NC inducers. Loss-of-function studies indicate that both of these ligands are necessary to specify the NC; however, it is unclear whether these signaling molecules are operating in the same or in parallel pathways to generate the NC. Here, we describe experiments addressing this outstanding question. We show that although Wnt8 expression can restore NC progenitors in Fgf8a-deficient embryos, Fgf8a is unable to rescue NC formation in Wnt8-depleted embryos. Moreover, the NC-inducing activity of Fgf8a in neuralized explants is strongly repressed by co-injection of a Wnt8 or a beta-catenin morpholino, suggesting that the activity of these two signaling molecules is linked. Consistent with these observations, Fgf8a is a potent inducer of Wnt8 in both whole embryos and animal explants, and Fgf8a knockdown results in a dramatic loss of Wnt8 expression in the mesoderm. We propose that Fgf8a induces NC indirectly through the activation of Wnt8 in the paraxial mesoderm, which in turn promotes NC formation in the overlying ectoderm primed by Bmp antagonists.
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Affiliation(s)
- Chang-Soo Hong
- Department of Biological Science, College of Natural Sciences, Daegu University, Jillyang, Gyeongsan, Gyeongbuk 712-714, South Korea
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13
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Lee RHK, Iioka H, Ohashi M, Iemura SI, Natsume T, Kinoshita N. XRab40 and XCullin5 form a ubiquitin ligase complex essential for the noncanonical Wnt pathway. EMBO J 2007; 26:3592-606. [PMID: 17627283 PMCID: PMC1949004 DOI: 10.1038/sj.emboj.7601781] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Accepted: 06/11/2007] [Indexed: 12/17/2022] Open
Abstract
Rab GTPases are key regulators of intracellular membrane trafficking. We sought to elucidate the roles of Rab GTPases in Xenopus gastrulation, and found that a Xenopus homolog of Rab40 (XRab40) is required for normal gastrulation. XRab40 is localized at the Golgi apparatus and interacts with ElonginB/C and Cullin5 to form a ubiquitin ligase. XRab40/XCullin5 functions cooperatively and regulates the ubiquitination and localization of Rap2 GTPase. Furthermore, XRab40/XCullin5 regulates the membrane localization of Dishevelled (Dsh), a key signaling molecule in the Wnt pathway, through Rap2 and its effector Misshapen/Nck-interacting kinase (XMINK). XMINK interacts with Dsh, and is translocated to the plasma membrane by Wnt activation. We propose a novel signaling cascade consisting of XRab40/XCullin5, Rap2 and XMINK, which plays a crucial role in the regulation of the noncanonical Wnt pathway.
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Affiliation(s)
- Rebecca Hui Kwan Lee
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
- Department of Molecular Biomechanics, The Graduate University for Advanced Studies; Okazaki, Aichi, Japan
| | - Hidekazu Iioka
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Masato Ohashi
- Okazaki Institute for Integrative Bioscience, National Institute of Natural Sciences, Okazaki, Japan
| | - Shun-ichiro Iemura
- National Institutes of Advanced Industrial Science and Technology; Biological Information Research Center; Tokyo, Japan
| | - Tohru Natsume
- National Institutes of Advanced Industrial Science and Technology; Biological Information Research Center; Tokyo, Japan
| | - Noriyuki Kinoshita
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
- Department of Molecular Biomechanics, The Graduate University for Advanced Studies; Okazaki, Aichi, Japan
- Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan. Tel.: +81 564 55 7573; Fax: +81 564 55 7571; E-mail:
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Carmona-Fontaine C, Acuña G, Ellwanger K, Niehrs C, Mayor R. Neural crests are actively precluded from the anterior neural fold by a novel inhibitory mechanism dependent on Dickkopf1 secreted by the prechordal mesoderm. Dev Biol 2007; 309:208-21. [PMID: 17669393 DOI: 10.1016/j.ydbio.2007.07.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 06/13/2007] [Accepted: 07/06/2007] [Indexed: 12/13/2022]
Abstract
It is known the interactions between the neural plate and epidermis generate neural crest (NC), but it is unknown why the NC develops only at the lateral border of the neural plate and not in the anterior fold. Using grafting experiments we show that there is a previously unidentified mechanism that precludes NC from the anterior region. We identify prechordal mesoderm as the tissue that inhibits NC in the anterior territory and show that the Wnt/beta-catenin antagonist Dkk1, secreted by this tissue, is sufficient to mimic this NC inhibition. We show that Dkk1 is required for preventing the formation of NC in the anterior neural folds as loss-of-function experiments using a Dkk1 blocking antibody in Xenopus as well as the analysis of Dkk1-null mouse embryos transform the anterior neural fold into NC. This can be mimicked by Wnt/beta-catenin signaling activation without affecting the anterior posterior patterning of the neural plate, or placodal specification. Finally, we show that the NC cells induced at the anterior neural fold are able to migrate and differentiate as normal NC. These results demonstrate that anterior regions of the embryo lack NC because of a mechanism, conserved from fish to mammals, that suppresses Wnt/beta-catenin signaling via Dkk1.
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15
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Ou CY, Wang CH, Jiang J, Chien CT. Suppression of Hedgehog signaling by Cul3 ligases in proliferation control of retinal precursors. Dev Biol 2007; 308:106-19. [PMID: 17559828 DOI: 10.1016/j.ydbio.2007.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 05/08/2007] [Accepted: 05/10/2007] [Indexed: 02/04/2023]
Abstract
Cullin-RING ubiquitin ligases ubiquitinate protein substrates and control their levels through degradation. Here we show that cullin3 (Cul3) suppresses Hedgehog (Hh) signaling through downregulating the level of the signaling pathway effector cubitus interruptus (Ci). High-level Hh signaling promotes Cul3-dependent Ci degradation, leading to the downregulation of Hh signaling. This process is manifested in controlling cell proliferation during Drosophila retinal development. In Cul3 mutants, the population of interommatidial cells is increased, which can be mimicked by overexpression of Ci and suppressed by depleting endogenous Ci. Hh also regulates the population of interommatidial cells in the pupal stage. Alterations in the interommatidial cell population correlate with alterations in precursor proliferation in the second mitotic wave of larval eye discs. Taken together, these results suggest that Cul3 downregulates Ci levels to modulate Hh signaling activity, thus ensuring proper cell proliferation during retinal development.
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Affiliation(s)
- Chan-Yen Ou
- Taiwan International Graduate Program, Graduate Institute of Life Science, National Defense Medical Center and Academia Sinica, Taipei, Taiwan
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16
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Chen JA, Chu ST, Amaya E. Maintenance of motor neuron progenitors in Xenopus requires a novel localized cyclin. EMBO Rep 2007; 8:287-92. [PMID: 17304238 PMCID: PMC1808035 DOI: 10.1038/sj.embor.7400903] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 11/27/2006] [Accepted: 12/19/2006] [Indexed: 12/22/2022] Open
Abstract
The ventral spinal cord contains a pool of motor neuron progenitors (pMNs), which sequentially generate motor neurons and oligodendrocytes in the embryo. The mechanisms responsible for the maintenance of pMNs are not clearly understood. We have identified a novel cyclin, cyclin Dx (ccndx), which is specifically expressed in pMNs in Xenopus. Here, we show that inhibition of ccndx causes paralysis in embryos. Furthermore, we show that maintenance of pMNs requires ccndx function. In addition, inhibition of ccndx results in the specific loss of differentiated motor neurons. However, the expression of interneuron or sensory neuron markers is unaffected in these embryos, suggesting that the role of ccndx is specifically to maintain pMNs. Thus, we have identified, for the first time, a tissue-specific cell-cycle regulator that is essential for the maintenance of a pool of neural progenitors in the vertebrate spinal cord.
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Affiliation(s)
- Jun-An Chen
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Sin-Tak Chu
- Institute of Biological Chemistry, Academia Sinica, Post Box 23-106, Taipei, Taiwan
| | - Enrique Amaya
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
- The Healing Foundation Centre, Michael Smith Building, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Tel: 44 161 275 1716; Fax: 44 161 275 1505; E-mail:
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17
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Raible DW. Development of the neural crest: achieving specificity in regulatory pathways. Curr Opin Cell Biol 2006; 18:698-703. [PMID: 17030122 DOI: 10.1016/j.ceb.2006.09.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Accepted: 09/29/2006] [Indexed: 11/25/2022]
Abstract
Recent studies have revealed the signaling pathways and downstream effectors involved in the specification of the neural crest. Neural crest cells are generated from a zone at the neurectoderm border in response to Wnt and BMP signals. BMP signals are involved in establishing a competency zone at the border of the neurectoderm, while subsequent Wnt signals specify neural crest cells. Combinations of transcription factors, including pax and msx gene products, act downstream of these pathways to integrate signals and establish the neural crest. Mechanisms are emerging for how specificity is generated from reiterated signals and effectors.
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Affiliation(s)
- David W Raible
- University of Washington, Department of Biological Structure, Seattle, WA 98195-7420, USA.
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