1
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Pühringer M, Eisenkölbl A, Gröppel G. Expanding the phenotype of RBCK1-associated polyglucosan body myopathy type 1. Mol Genet Metab Rep 2024; 38:101031. [PMID: 38077957 PMCID: PMC10698560 DOI: 10.1016/j.ymgmr.2023.101031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/21/2023] [Accepted: 11/22/2023] [Indexed: 03/13/2024] Open
Abstract
Polyglucosan body myopathy-1 (PGBM1) is an extremely rare glycogen storage diseases that leads to muscle weakness and cardiomyopathy due to the accumulation of polyglucosan bodies. The clinical presentation appears to be partially dependent on the genetic mutation, but no clear genotype/phenotype correlation is currently possible. We describe a 7 year old patient, who initially presented with recurrent vomiting and respiratory infections until her first year of life. Diagnostic workup revealed an achalasia and the whole exome sequencing revealed an homozygous RBCK1 (RANBP2-type and C3HC4-type zinc finger containing 1) variant (c.896_899delAGTG) located in exon 7 (mid-domain), which has also been described in 4 patients with PGBM1. The unusual presentation with gastrointestinal and respiratory symptoms before the development of progressive muscle weakness expands the phenotype of this disease.
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Affiliation(s)
- Manuel Pühringer
- Department of Paediatrics and Adolescent Medicine, Kepler University Hospital, Linz, Austria
| | - Astrid Eisenkölbl
- Department of Paediatrics and Adolescent Medicine, Kepler University Hospital, Linz, Austria
| | - Gudrun Gröppel
- Department of Paediatrics and Adolescent Medicine, Kepler University Hospital, Linz, Austria
- Department of Neurology, Kepler University Hospital, Linz, Austria
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2
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Zhang YY, Peng J, Luo XJ. Post-translational modification of MALT1 and its role in B cell- and T cell-related diseases. Biochem Pharmacol 2022; 198:114977. [PMID: 35218741 DOI: 10.1016/j.bcp.2022.114977] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/18/2022] [Accepted: 02/18/2022] [Indexed: 02/06/2023]
Abstract
Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is a multifunctional protein. MALT1 functions as an adaptor protein to assemble and recruit proteins such as B-cell lymphoma 10 (BCL10) and caspase-recruitment domain (CARD)-containing coiled-coil protein 11 (CARD11). Conversely it also acts as a paracaspase to cleave specified substrates. Because of its involvement in immunity, inflammation and cancer through its dual functions of scaffolding and catalytic activity, MALT1 is becoming a promising therapeutic target in B cell- and T cell-related diseases. There is growing evidence that the function of MALT1 is subtly modulated via post-translational modifications. This review summarized recent progress in relevant studies regarding the physiological and pathophysiological functions of MALT1, post-translational modifications of MALT1 and its role in B cell- and T cell- related diseases. In addition, the current available MALT1 inhibitors were also discussed.
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Affiliation(s)
- Yi-Yue Zhang
- Department of Pharmacology, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha 410078, China
| | - Jun Peng
- Department of Pharmacology, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
| | - Xiu-Ju Luo
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha 410013, China.
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3
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Small molecules targeting ubiquitination to control inflammatory diseases. Drug Discov Today 2021; 26:2414-2422. [PMID: 33992766 DOI: 10.1016/j.drudis.2021.04.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/23/2021] [Accepted: 04/07/2021] [Indexed: 12/29/2022]
Abstract
The ubiquitination and deubiquitination of proteins govern signal transduction in every aspect of physiology and pathology, especially in cancer, inflammation, and autoimmune diseases. Rapid progress has been made in obtaining an in-depth understanding of the ubiquitination system since its first discovery during the 1970s. Manipulation of ubiquitination by small molecules is considered a novel therapeutic avenue. In this review, we summarize key applications of small molecules targeting ubiquitination enzymes and currently available technologies applied to the discovery of small molecules that control ubiquitination.
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4
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PHLPPing the balance: restoration of protein kinase C in cancer. Biochem J 2021; 478:341-355. [PMID: 33502516 DOI: 10.1042/bcj20190765] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 12/28/2022]
Abstract
Protein kinase signalling, which transduces external messages to mediate cellular growth and metabolism, is frequently deregulated in human disease, and specifically in cancer. As such, there are 77 kinase inhibitors currently approved for the treatment of human disease by the FDA. Due to their historical association as the receptors for the tumour-promoting phorbol esters, PKC isozymes were initially targeted as oncogenes in cancer. However, a meta-analysis of clinical trials with PKC inhibitors in combination with chemotherapy revealed that these treatments were not advantageous, and instead resulted in poorer outcomes and greater adverse effects. More recent studies suggest that instead of inhibiting PKC, therapies should aim to restore PKC function in cancer: cancer-associated PKC mutations are generally loss-of-function and high PKC protein is protective in many cancers, including most notably KRAS-driven cancers. These recent findings have reframed PKC as having a tumour suppressive function. This review focusses on a potential new mechanism of restoring PKC function in cancer - through targeting of its negative regulator, the Ser/Thr protein phosphatase PHLPP. This phosphatase regulates PKC steady-state levels by regulating the phosphorylation of a key site, the hydrophobic motif, whose phosphorylation is necessary for the stability of the enzyme. We also consider whether the phosphorylation of the potent oncogene KRAS provides a mechanism by which high PKC expression may be protective in KRAS-driven human cancers.
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5
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Abstract
The 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal "processor" for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.
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Affiliation(s)
- Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, 02215, Massachusetts, USA. .,School of Physics, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
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6
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Parker PJ, Brown SJ, Calleja V, Chakravarty P, Cobbaut M, Linch M, Marshall JJT, Martini S, McDonald NQ, Soliman T, Watson L. Equivocal, explicit and emergent actions of PKC isoforms in cancer. Nat Rev Cancer 2021; 21:51-63. [PMID: 33177705 DOI: 10.1038/s41568-020-00310-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
The maturing mutational landscape of cancer genomes, the development and application of clinical interventions and evolving insights into tumour-associated functions reveal unexpected features of the protein kinase C (PKC) family of serine/threonine protein kinases. These advances include recent work showing gain or loss-of-function mutations relating to driver or bystander roles, how conformational constraints and plasticity impact this class of proteins and how emergent cancer-associated properties may offer opportunities for intervention. The profound impact of the tumour microenvironment, reflected in the efficacy of immune checkpoint interventions, further prompts to incorporate PKC family actions and interventions in this ecosystem, informed by insights into the control of stromal and immune cell functions. Drugging PKC isoforms has offered much promise, but when and how is not obvious.
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Affiliation(s)
- Peter J Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK.
- School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Campus, London, UK.
| | - Sophie J Brown
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Veronique Calleja
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | | | - Mathias Cobbaut
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Mark Linch
- UCL Cancer Institute, University College London, London, UK
| | | | - Silvia Martini
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Neil Q McDonald
- Signalling and Structural Biology Laboratory, Francis Crick Institute, London, UK
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, UK
| | - Tanya Soliman
- Centre for Cancer Genomics and Computational Biology, Bart's Cancer Institute, London, UK
| | - Lisa Watson
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
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7
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ABL1-dependent OTULIN phosphorylation promotes genotoxic Wnt/β-catenin activation to enhance drug resistance in breast cancers. Nat Commun 2020; 11:3965. [PMID: 32770022 PMCID: PMC7414915 DOI: 10.1038/s41467-020-17770-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 07/17/2020] [Indexed: 12/16/2022] Open
Abstract
Dysregulated Wnt/β-catenin activation plays a critical role in cancer progression, metastasis, and drug resistance. Genotoxic agents such as radiation and chemotherapeutics have been shown to activate the Wnt/β-catenin signaling although the underlying mechanism remains incompletely understood. Here, we show that genotoxic agent-activated Wnt/β-catenin signaling is independent of the FZD/LRP heterodimeric receptors and Wnt ligands. OTULIN, a linear linkage-specific deubiquitinase, is essential for the DNA damage-induced β-catenin activation. OTULIN inhibits linear ubiquitination of β-catenin, which attenuates its Lys48-linked ubiquitination and proteasomal degradation upon DNA damage. The association with β-catenin is enhanced by OTULIN Tyr56 phosphorylation, which depends on genotoxic stress-activated ABL1/c-Abl. Inhibiting OTULIN or Wnt/β-catenin sensitizes triple-negative breast cancer xenograft tumors to chemotherapeutics and reduces metastasis. Increased OTULIN levels are associated with aggressive molecular subtypes and poor survival in breast cancer patients. Thus, OTULIN-mediated Wnt/β-catenin activation upon genotoxic treatments promotes drug resistance and metastasis in breast cancers. Genotoxic agents have been shown to activate the Wnt/β-catenin signaling but the underlying mechanism remains unclear. Here, the authors show that upon DNA damage, the deubiquitinase OTULIN activates Wnt/β-catenin signaling by inhibiting linear ubiquitination, K48-linked polyubiquitination, and proteasomal degradation of β-catenin.
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8
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Systematic analysis of alterations in the ubiquitin proteolysis system reveals its contribution to driver mutations in cancer. ACTA ACUST UNITED AC 2019; 1:122-135. [DOI: 10.1038/s43018-019-0001-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 10/11/2019] [Indexed: 12/21/2022]
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9
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Marrocco V, Bogomolovas J, Ehler E, Dos Remedios CG, Yu J, Gao C, Lange S. PKC and PKN in heart disease. J Mol Cell Cardiol 2019; 128:212-226. [PMID: 30742812 PMCID: PMC6408329 DOI: 10.1016/j.yjmcc.2019.01.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 12/22/2022]
Abstract
The protein kinase C (PKC) and closely related protein kinase N (PKN) families of serine/threonine protein kinases play crucial cellular roles. Both kinases belong to the AGC subfamily of protein kinases that also include the cAMP dependent protein kinase (PKA), protein kinase B (PKB/AKT), protein kinase G (PKG) and the ribosomal protein S6 kinase (S6K). Involvement of PKC family members in heart disease has been well documented over the years, as their activity and levels are mis-regulated in several pathological heart conditions, such as ischemia, diabetic cardiomyopathy, as well as hypertrophic or dilated cardiomyopathy. This review focuses on the regulation of PKCs and PKNs in different pathological heart conditions and on the influences that PKC/PKN activation has on several physiological processes. In addition, we discuss mechanisms by which PKCs and the closely related PKNs are activated and turned-off in hearts, how they regulate cardiac specific downstream targets and pathways, and how their inhibition by small molecules is explored as new therapeutic target to treat cardiomyopathies and heart failure.
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Affiliation(s)
- Valeria Marrocco
- Division of Cardiology, School of Medicine, University of California-San Diego, La Jolla, USA
| | - Julius Bogomolovas
- Division of Cardiology, School of Medicine, University of California-San Diego, La Jolla, USA; Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, School of Cardiovascular Medicine and Sciences, British Heart Foundation Research Excellence Centre, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | | | - Jiayu Yu
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Gao
- Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine at UCLA, University of California-Los Angeles, Los Angeles, USA.
| | - Stephan Lange
- Division of Cardiology, School of Medicine, University of California-San Diego, La Jolla, USA; University of Gothenburg, Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, Gothenburg, Sweden.
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10
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Magnani ND, Dada LA, Sznajder JI. Ubiquitin-proteasome signaling in lung injury. Transl Res 2018; 198:29-39. [PMID: 29752900 PMCID: PMC6986356 DOI: 10.1016/j.trsl.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/15/2018] [Accepted: 04/16/2018] [Indexed: 12/21/2022]
Abstract
Cell homeostasis requires precise coordination of cellular proteins function. Ubiquitination is a post-translational modification that modulates protein half-life and function and is tightly regulated by ubiquitin E3 ligases and deubiquitinating enzymes. Lung injury can progress to acute respiratory distress syndrome that is characterized by an inflammatory response and disruption of the alveolocapillary barrier resulting in alveolar edema accumulation and hypoxemia. Ubiquitination plays an important role in the pathobiology of acute lung injury as it regulates the proteins modulating the alveolocapillary barrier and the inflammatory response. Better understanding of the signaling pathways regulated by ubiquitination may lead to novel therapeutic approaches by targeting specific elements of the ubiquitination pathways.
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Affiliation(s)
- Natalia D Magnani
- Pulmonary and Critical Care Division, Northwestern Feinberg School of Medicine, Chicago, Illinois
| | - Laura A Dada
- Pulmonary and Critical Care Division, Northwestern Feinberg School of Medicine, Chicago, Illinois
| | - Jacob I Sznajder
- Pulmonary and Critical Care Division, Northwestern Feinberg School of Medicine, Chicago, Illinois.
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11
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HIF and HOIL-1L-mediated PKCζ degradation stabilizes plasma membrane Na,K-ATPase to protect against hypoxia-induced lung injury. Proc Natl Acad Sci U S A 2017; 114:E10178-E10186. [PMID: 29109255 DOI: 10.1073/pnas.1713563114] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Organisms have evolved adaptive mechanisms in response to stress for cellular survival. During acute hypoxic stress, cells down-regulate energy-consuming enzymes such as Na,K-ATPase. Within minutes of alveolar epithelial cell (AEC) exposure to hypoxia, protein kinase C zeta (PKCζ) phosphorylates the α1-Na,K-ATPase subunit and triggers it for endocytosis, independently of the hypoxia-inducible factor (HIF). However, the Na,K-ATPase activity is essential for cell homeostasis. HIF induces the heme-oxidized IRP2 ubiquitin ligase 1L (HOIL-1L), which leads to PKCζ degradation. Here we report a mechanism of prosurvival adaptation of AECs to prolonged hypoxia where PKCζ degradation allows plasma membrane Na,K-ATPase stabilization at ∼50% of normoxic levels, preventing its excessive down-regulation and cell death. Mice lacking HOIL-1L in lung epithelial cells (CreSPC/HOIL-1Lfl/fl ) were sensitized to hypoxia because they express higher levels of PKCζ and, consequently, lower plasma membrane Na,K-ATPase levels, which increased cell death and worsened lung injury. In AECs, expression of an α1-Na,K-ATPase construct bearing an S18A (α1-S18A) mutation, which precludes PKCζ phosphorylation, stabilized the Na,K-ATPase at the plasma membrane and prevented hypoxia-induced cell death even in the absence of HOIL-1L. Adenoviral overexpression of the α1-S18A mutant Na,K-ATPase in vivo rescued the enhanced sensitivity of CreSPC/HOIL-1Lfl/fl mice to hypoxic lung injury. These data suggest that stabilization of Na,K-ATPase during severe hypoxia is a HIF-dependent process involving PKCζ degradation. Accordingly, we provide evidence of an important adaptive mechanism to severe hypoxia, whereby halting the exaggerated down-regulation of plasma membrane Na,K-ATPase prevents cell death and lung injury.
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12
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Hrdinka M, Gyrd-Hansen M. The Met1-Linked Ubiquitin Machinery: Emerging Themes of (De)regulation. Mol Cell 2017; 68:265-280. [PMID: 29053955 DOI: 10.1016/j.molcel.2017.09.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/21/2017] [Accepted: 08/31/2017] [Indexed: 01/24/2023]
Abstract
The linear ubiquitin chain assembly complex, LUBAC, is the only known mammalian ubiquitin ligase that makes methionine 1 (Met1)-linked polyubiquitin (also referred to as linear ubiquitin). A decade after LUBAC was discovered as a cellular activity of unknown function, there are now many lines of evidence connecting Met1-linked polyubiquitin to NF-κB signaling, cell death, inflammation, immunity, and cancer. We now know that Met1-linked polyubiquitin has potent signaling functions and that its deregulation is connected to disease. Indeed, mutations and deficiencies in several factors involved in conjugation and deconjugation of Met1-linked polyubiquitin have been implicated in immune-related disorders. Here, we discuss current knowledge and recent insights into the role and regulation of Met1-linked polyubiquitin, with an emphasis on the mechanisms controlling the function of LUBAC.
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Affiliation(s)
- Matous Hrdinka
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, UK
| | - Mads Gyrd-Hansen
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, UK.
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13
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Abstract
The ubiquitin proteasome system controls the concentrations of regulatory proteins and removes damaged and misfolded proteins from cells. Proteins are targeted to the protease at the center of this system, the proteasome, by ubiquitin tags, but ubiquitin is also used as a signal in other cellular processes. Specificity is conferred by the size and structure of the ubiquitin tags, which are recognized by receptors associated with the different cellular processes. However, the ubiquitin code remains ambiguous, and the same ubiquitin tag can target different proteins to different fates. After binding substrate protein at the ubiquitin tag, the proteasome initiates degradation at a disordered region in the substrate. The proteasome has pronounced preferences for the initiation site, and its recognition represents a second component of the degradation signal.
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Affiliation(s)
- Houqing Yu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712;
| | - Andreas Matouschek
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712;
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14
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Elton L, Carpentier I, Verhelst K, Staal J, Beyaert R. The multifaceted role of the E3 ubiquitin ligase HOIL-1: beyond linear ubiquitination. Immunol Rev 2016; 266:208-21. [PMID: 26085217 DOI: 10.1111/imr.12307] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ubiquitination controls and fine-tunes many signaling processes driving immunity, inflammation, and cancer. The E3 ubiquitin ligase HOIL-1 (heme-oxidized IRP2 ubiquitin ligase-1) is increasingly implicated in different signaling pathways and plays a vital role in immune regulation. HOIL-1 co operates with the E3 ubiquitin ligase HOIP (HOIL-1 interacting protein) to modify specific nuclear factor-κB (NF-κB) signaling proteins with linear M1-linked polyubiquitin chains. In addition, through its ability to also add K48-linked polyubiquitin chains to specific substrates, HOIL-1 has been linked with antiviral signaling, iron and xenobiotic metabolism, cell death, and cancer. HOIL-1 deficiency in humans leads to myopathy, amylopectinosis, auto-inflammation, and immunodeficiency associated with an increased frequency of bacterial infections. HOIL-1-deficient mice exhibit amylopectin-like deposits in the myocardium, pathogen-specific immunodeficiency, but minimal signs of hyper-inflammation. This review summarizes current knowledge on the mechanism of action of HOIL-1 and highlights recent advances regarding its role in health and disease.
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Affiliation(s)
- Lynn Elton
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Isabelle Carpentier
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Kelly Verhelst
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Jens Staal
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Rudi Beyaert
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
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15
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16
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Elton L, Carpentier I, Staal J, Driege Y, Haegman M, Beyaert R. MALT1 cleaves the E3 ubiquitin ligase HOIL-1 in activated T cells, generating a dominant negative inhibitor of LUBAC-induced NF-κB signaling. FEBS J 2015; 283:403-12. [DOI: 10.1111/febs.13597] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 11/10/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Lynn Elton
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Department of Biomedical Molecular Biology; Ghent University; Belgium
| | - Isabelle Carpentier
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Department of Biomedical Molecular Biology; Ghent University; Belgium
| | - Jens Staal
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Department of Biomedical Molecular Biology; Ghent University; Belgium
| | - Yasmine Driege
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Department of Biomedical Molecular Biology; Ghent University; Belgium
| | - Mira Haegman
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Department of Biomedical Molecular Biology; Ghent University; Belgium
| | - Rudi Beyaert
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Department of Biomedical Molecular Biology; Ghent University; Belgium
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17
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Klein T, Fung SY, Renner F, Blank MA, Dufour A, Kang S, Bolger-Munro M, Scurll JM, Priatel JJ, Schweigler P, Melkko S, Gold MR, Viner RI, Régnier CH, Turvey SE, Overall CM. The paracaspase MALT1 cleaves HOIL1 reducing linear ubiquitination by LUBAC to dampen lymphocyte NF-κB signalling. Nat Commun 2015; 6:8777. [PMID: 26525107 PMCID: PMC4659944 DOI: 10.1038/ncomms9777] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/02/2015] [Indexed: 12/12/2022] Open
Abstract
Antigen receptor signalling activates the canonical NF-κB pathway via the CARD11/BCL10/MALT1 (CBM) signalosome involving key, yet ill-defined roles for linear ubiquitination. The paracaspase MALT1 cleaves and removes negative checkpoint proteins, amplifying lymphocyte responses in NF-κB activation and in B-cell lymphoma subtypes. To identify new human MALT1 substrates, we compare B cells from the only known living MALT1(mut/mut) patient with healthy MALT1(+/mut) family members using 10-plex Tandem Mass Tag TAILS N-terminal peptide proteomics. We identify HOIL1 of the linear ubiquitin chain assembly complex as a novel MALT1 substrate. We show linear ubiquitination at B-cell receptor microclusters and signalosomes. Late in the NF-κB activation cycle HOIL1 cleavage transiently reduces linear ubiquitination, including of NEMO and RIP1, dampening NF-κB activation and preventing reactivation. By regulating linear ubiquitination, MALT1 is both a positive and negative pleiotropic regulator of the human canonical NF-κB pathway-first promoting activation via the CBM--then triggering HOIL1-dependent negative-feedback termination, preventing reactivation.
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Affiliation(s)
- Theo Klein
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Department of Oral Biological and Medical Science, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Shan-Yu Fung
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Child &Family Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada V6T 1Z3
| | - Florian Renner
- Novartis Institutes for BioMedical Research, Novartis Campus, Basel, CH-4056, Switzerland
| | - Michael A Blank
- Thermo Fisher Scientific, 355 River Oaks Parkway, San Jose, 95134 California, USA
| | - Antoine Dufour
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Department of Oral Biological and Medical Science, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Sohyeong Kang
- Child &Family Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada V6T 1Z3.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4
| | - Madison Bolger-Munro
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Joshua M Scurll
- Department of Mathematics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - John J Priatel
- Child &Family Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada V6T 1Z3.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4
| | - Patrick Schweigler
- Novartis Institutes for BioMedical Research, Novartis Campus, Basel, CH-4056, Switzerland
| | - Samu Melkko
- Novartis Institutes for BioMedical Research, Novartis Campus, Basel, CH-4056, Switzerland
| | - Michael R Gold
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Rosa I Viner
- Thermo Fisher Scientific, 355 River Oaks Parkway, San Jose, 95134 California, USA
| | - Catherine H Régnier
- Novartis Institutes for BioMedical Research, Novartis Campus, Basel, CH-4056, Switzerland
| | - Stuart E Turvey
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Child &Family Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada V6T 1Z3
| | - Christopher M Overall
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Department of Oral Biological and Medical Science, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.,Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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18
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Queisser MA, Dada LA, Deiss-Yehiely N, Angulo M, Zhou G, Kouri FM, Knab LM, Liu J, Stegh AH, DeCamp MM, Budinger GRS, Chandel NS, Ciechanover A, Iwai K, Sznajder JI. HOIL-1L functions as the PKCζ ubiquitin ligase to promote lung tumor growth. Am J Respir Crit Care Med 2014; 190:688-98. [PMID: 25118570 DOI: 10.1164/rccm.201403-0463oc] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
RATIONALE Protein kinase C zeta (PKCζ) has been reported to act as a tumor suppressor. Deletion of PKCζ in experimental cancer models has been shown to increase tumor growth. However, the mechanisms of PKCζ down-regulation in cancerous cells have not been previously described. OBJECTIVES To determine the molecular mechanisms that lead to decreased PKCζ expression and thus increased survival in cancer cells and tumor growth. METHODS The levels of expression of heme-oxidized IRP2 ubiquitin ligase 1L (HOIL-1L), HOIL-1-interacting protein (HOIP), Shank-associated RH domain-interacting protein (SHARPIN), and PKCζ were analyzed by Western blot and/or quantitative real-time polymerase chain reaction in different cell lines. Coimmunoprecipitation experiments were used to demonstrate the interaction between HOIL-1L and PKCζ. Ubiquitination was measured in an in vitro ubiquitination assay and by Western blot with specific antibodies. The role of hypoxia-inducible factor (HIF) was determined by gain/loss-of-function experiments. The effect of HOIL-1L expression on cell death was investigated using RNA interference approaches in vitro and on tumor growth in mice models. Increased HOIL-1L and decreased PKCζ expression was assessed in lung adenocarcinoma and glioblastoma multiforme and documented in several other cancer types by oncogenomic analysis. MEASUREMENTS AND MAIN RESULTS Hypoxia is a hallmark of rapidly growing solid tumors. We found that during hypoxia, PKCζ is ubiquitinated and degraded via the ubiquitin ligase HOIL-1L, a component of the linear ubiquitin chain assembly complex (LUBAC). In vitro ubiquitination assays indicate that HOIL-1L ubiquitinates PKCζ at Lys-48, targeting it for proteasomal degradation. In a xenograft tumor model and lung cancer model, we found that silencing of HOIL-1L increased the abundance of PKCζ and decreased the size of tumors, suggesting that lower levels of HOIL-1L promote survival. Indeed, mRNA transcript levels of HOIL-1L were elevated in tumor of patients with lung adenocarcinoma, and in a lung adenocarcinoma tissue microarray the levels of HOIL-1L were associated with high-grade tumors. Moreover, we found that HOIL-1L expression was regulated by HIFs. Interestingly, the actions of HOIL-1L were independent of LUBAC. CONCLUSIONS These data provide first evidence of a mechanism of cancer cell adaptation to hypoxia where HIFs regulate HOIL-1L, which targets PKCζ for degradation to promote tumor survival. We provided a proof of concept that silencing of HOIL-1L impairs lung tumor growth and that HOIL-1L expression predicts survival rate in cancer patients suggesting that HOIL-1L is an attractive target for cancer therapy.
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19
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Rodgers MA, Bowman JW, Fujita H, Orazio N, Shi M, Liang Q, Amatya R, Kelly TJ, Iwai K, Ting J, Jung JU. The linear ubiquitin assembly complex (LUBAC) is essential for NLRP3 inflammasome activation. ACTA ACUST UNITED AC 2014; 211:1333-47. [PMID: 24958845 PMCID: PMC4076580 DOI: 10.1084/jem.20132486] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Linear ubiquitination is a newly discovered posttranslational modification that is currently restricted to a small number of known protein substrates. The linear ubiquitination assembly complex (LUBAC), consisting of HOIL-1L, HOIP, and Sharpin, has been reported to activate NF-κB-mediated transcription in response to receptor signaling by ligating linear ubiquitin chains to Nemo and Rip1. Despite recent advances, the detailed roles of LUBAC in immune cells remain elusive. We demonstrate a novel HOIL-1L function as an essential regulator of the activation of the NLRP3/ASC inflammasome in primary bone marrow-derived macrophages (BMDMs) independently of NF-κB activation. Mechanistically, HOIL-1L is required for assembly of the NLRP3/ASC inflammasome and the linear ubiquitination of ASC, which we identify as a novel LUBAC substrate. Consequently, we find that HOIL-1L(-/-) mice have reduced IL-1β secretion in response to in vivo NLRP3 stimulation and survive lethal challenge with LPS. Together, these data demonstrate that linear ubiquitination is required for NLRP3 inflammasome activation, defining the molecular events of NLRP3 inflammasome activation and expanding the role of LUBAC as an innate immune regulator. Furthermore, our observation is clinically relevant because patients lacking HOIL-1L expression suffer from pyogenic bacterial immunodeficiency, providing a potential new therapeutic target for enhancing inflammation in immunodeficient patients.
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Affiliation(s)
- Mary A Rodgers
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - James W Bowman
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Hiroaki Fujita
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Nicole Orazio
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Mude Shi
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Qiming Liang
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Rina Amatya
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Thomas J Kelly
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Kazuhiro Iwai
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Jenny Ting
- Department of Microbiology-Immunology, Lineberger Comprehensive Cancer Center, Center for Translational Immunology and Institute for Inflammatory Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Jae U Jung
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
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20
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Abstract
The RBR (RING-BetweenRING-RING) or TRIAD [two RING fingers and a DRIL (double RING finger linked)] E3 ubiquitin ligases comprise a group of 12 complex multidomain enzymes. This unique family of E3 ligases includes parkin, whose dysfunction is linked to the pathogenesis of early-onset Parkinson's disease, and HOIP (HOIL-1-interacting protein) and HOIL-1 (haem-oxidized IRP2 ubiquitin ligase 1), members of the LUBAC (linear ubiquitin chain assembly complex). The RBR E3 ligases share common features with both the larger RING and HECT (homologous with E6-associated protein C-terminus) E3 ligase families, directly catalysing ubiquitin transfer from an intrinsic catalytic cysteine housed in the C-terminal domain, as well as recruiting thioester-bound E2 enzymes via a RING domain. Recent three-dimensional structures and biochemical findings of the RBRs have revealed novel protein domain folds not previously envisioned and some surprising modes of regulation that have raised many questions. This has required renaming two of the domains in the RBR E3 ligases to more accurately reflect their structures and functions: the C-terminal Rcat (required-for-catalysis) domain, essential for catalytic activity, and a central BRcat (benign-catalytic) domain that adopts the same fold as the Rcat, but lacks a catalytic cysteine residue and ubiquitination activity. The present review discusses how three-dimensional structures of RBR (RING1-BRcat-Rcat) E3 ligases have provided new insights into our understanding of the biochemical mechanisms of these important enzymes in ubiquitin biology.
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21
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Nilsson J, Schoser B, Laforet P, Kalev O, Lindberg C, Romero NB, Dávila López M, Akman HO, Wahbi K, Iglseder S, Eggers C, Engel AG, Dimauro S, Oldfors A. Polyglucosan body myopathy caused by defective ubiquitin ligase RBCK1. Ann Neurol 2014; 74:914-9. [PMID: 23798481 DOI: 10.1002/ana.23963] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/20/2013] [Accepted: 06/07/2013] [Indexed: 12/25/2022]
Abstract
Glycogen storage diseases are important causes of myopathy and cardiomyopathy. We describe 10 patients from 8 families with childhood or juvenile onset of myopathy, 8 of whom also had rapidly progressive cardiomyopathy, requiring heart transplant in 4. The patients were homozygous or compound heterozygous for missense or truncating mutations in RBCK1, which encodes for a ubiquitin ligase, and had extensive polyglucosan accumulation in skeletal muscle and in the heart in cases of cardiomyopathy. We conclude that RBCK1 deficiency is a frequent cause of polyglucosan storage myopathy associated with progressive muscle weakness and cardiomyopathy.
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Affiliation(s)
- Johanna Nilsson
- Department of Pathology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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22
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Wu ZH, Shi Y. When ubiquitin meets NF-κB: a trove for anti-cancer drug development. Curr Pharm Des 2013; 19:3263-75. [PMID: 23151140 DOI: 10.2174/1381612811319180010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/01/2012] [Indexed: 02/06/2023]
Abstract
During the last two decades, the studies on ubiquitination in regulating transcription factor NF-κB activation have elucidated the expanding role of ubiquitination in modulating cellular events by non-proteolytic mechanisms, as well as by proteasomal degradation. The significance of ubiquitination has also been recognized in regulating gene transcription, epigenetic modifications, kinase activation, DNA repair and subcellular translocation. This progress has been translated into novel strategies for developing anti-cancer therapeutics, exemplified by the success of the first FDA-approved proteasome inhibitor drug Bortezomib. Here we discuss the current understanding of the ubiquitin-proteasome system and how it is involved in regulating NF-κB signaling pathways in response to a variety of stimuli. We also focus on the recent progress of anti-cancer drug development targeting various steps of ubiquitination process, and the potential of these drugs in cancer treatment as related to their impact on NF-κB activation.
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Affiliation(s)
- Zhao-Hui Wu
- Department of Pathology and Laboratory Medicine, Center for Adult Cancer Research, University of Tennessee Health Science Center, 19 S. Manassas St., Memphis, TN 38163, USA.
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23
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Donley C, McClelland K, McKeen HD, Nelson L, Yakkundi A, Jithesh PV, Burrows J, McClements L, Valentine A, Prise KM, McCarthy HO, Robson T. Identification of RBCK1 as a novel regulator of FKBPL: implications for tumor growth and response to tamoxifen. Oncogene 2013; 33:3441-50. [PMID: 23912458 DOI: 10.1038/onc.2013.306] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 05/27/2013] [Accepted: 06/11/2013] [Indexed: 01/03/2023]
Abstract
FKBPL has been implicated in processes associated with cancer, including regulation of tumor growth and angiogenesis with high levels of FKBPL prognosticating for improved patient survival. Understanding how FKBPL levels are controlled within the cell is therefore critical. We have identified a novel role for RBCK1 as an FKBPL-interacting protein, which regulates FKBPL stability at the post-translational level via ubiquitination. Both RBCK1 and FKBPL are upregulated by 17-β-estradiol and interact within heat shock protein 90 chaperone complexes, together with estrogen receptor-α (ERα). Furthermore, FKBPL and RBCK1 associate with ERα at the promoter of the estrogen responsive gene, pS2, and regulate pS2 levels. MCF-7 clones stably overexpressing RBCK1 were shown to have reduced proliferation and increased levels of FKBPL and p21. Furthermore, these clones were resistant to tamoxifen therapy, suggesting that RBCK1 could be a predictive marker of response to endocrine therapy. RBCK1 knockdown using targeted small interfering RNA resulted in increased proliferation and increased sensitivity to tamoxifen treatment. Moreover, in support of our in vitro data, analysis of mRNA microarray data sets demonstrated that high levels of FKBPL and RBCK1 correlated with increased patient survival, whereas high RBCK1 predicted for a poor response to tamoxifen. Our findings support a role for RBCK1 in the regulation of FKBPL with important implications for estrogen receptor signaling, cell proliferation and response to endocrine therapy.
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Affiliation(s)
- C Donley
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - K McClelland
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - H D McKeen
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - L Nelson
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - A Yakkundi
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - P V Jithesh
- Liverpool Cancer Research UK Centre, University of Liverpool, Liverpool, UK
| | - J Burrows
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - L McClements
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - A Valentine
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - K M Prise
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, Northern Ireland
| | - H O McCarthy
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
| | - T Robson
- School of Pharmacy, McClay Research Centre, Queen's University, Belfast, Northern Ireland
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24
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Lum MA, Balaburski GM, Murphy ME, Black AR, Black JD. Heat shock proteins regulate activation-induced proteasomal degradation of the mature phosphorylated form of protein kinase C. J Biol Chem 2013; 288:27112-27127. [PMID: 23900841 DOI: 10.1074/jbc.m112.437095] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although alterations in stimulus-induced degradation of PKC have been implicated in disease, mechanistic understanding of this process remains limited. Evidence supports the existence of both proteasomal and lysosomal mechanisms of PKC processing. An established pathway involves rate-limiting priming site dephosphorylation of the activated enzyme and proteasomal clearance of the dephosphorylated protein. However, here we show that agonists promote down-regulation of endogenous PKCα with minimal accumulation of a nonphosphorylated species in multiple cell types. Furthermore, proteasome and lysosome inhibitors predominantly protect fully phosphorylated PKCα, pointing to this form as a substrate for degradation. Failure to detect substantive dephosphorylation of activated PKCα was not due to rephosphorylation because inhibition of Hsp70/Hsc70, which is required for re-priming, had only a minor effect on agonist-induced accumulation of nonphosphorylated protein. Thus, PKC degradation can occur in the absence of dephosphorylation. Further analysis revealed novel functions for Hsp70/Hsc70 and Hsp90 in the control of agonist-induced PKCα processing. These chaperones help to maintain phosphorylation of activated PKCα but have opposing effects on degradation of the phosphorylated protein; Hsp90 is protective, whereas Hsp70/Hsc70 activity is required for proteasomal processing of this species. Notably, down-regulation of nonphosphorylated PKCα shows little Hsp70/Hsc70 dependence, arguing that phosphorylated and nonphosphorylated species are differentially targeted for proteasomal degradation. Finally, lysosomal processing of activated PKCα is not regulated by phosphorylation or Hsps. Collectively, these data demonstrate that phosphorylated PKCα is a direct target for agonist-induced proteasomal degradation via an Hsp-regulated mechanism, and highlight the existence of a novel pathway of PKC desensitization in cells.
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Affiliation(s)
- Michelle A Lum
- From The Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950; Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | | | | | - Adrian R Black
- From The Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950; Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Jennifer D Black
- From The Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950; Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263.
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25
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Yang W, Xia Y, Cao Y, Zheng Y, Bu W, Zhang L, You MJ, Koh MY, Cote G, Aldape K, Li Y, Verma IM, Chiao PJ, Lu Z. EGFR-induced and PKCε monoubiquitylation-dependent NF-κB activation upregulates PKM2 expression and promotes tumorigenesis. Mol Cell 2012; 48:771-84. [PMID: 23123196 PMCID: PMC3526114 DOI: 10.1016/j.molcel.2012.09.028] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 06/05/2012] [Accepted: 09/19/2012] [Indexed: 01/28/2023]
Abstract
Many types of human tumor cells have overexpressed pyruvate kinase M2 (PKM2). However, the mechanism underlying this increased PKM2 expression remains to be defined. We demonstrate here that EGFR activation induces PLCγ1-dependent PKCε monoubiquitylation at Lys321 mediated by RINCK1 ubiquitin ligase. Monoubiquitylated PKCε interacts with a ubiquitin-binding domain in NEMO zinc finger and recruits the cytosolic IKK complex to the plasma membrane, where PKCε phosphorylates IKKβ at Ser177 and activates IKKβ. Activated RelA interacts with HIF1α, which is required for RelA to bind the PKM promoter. PKCε- and NF-κB-dependent PKM2 upregulation is required for EGFR-promoted glycolysis and tumorigenesis. In addition, PKM2 expression correlates with EGFR and IKKβ activity in human glioblastoma specimens and with grade of glioma malignancy. These findings highlight the distinct regulation of NF-κB by EGF, in contrast to TNF-α, and the importance of the metabolic cooperation between the EGFR and NF-κB pathways in PKM2 upregulation and tumorigenesis.
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MESH Headings
- Animals
- Brain Neoplasms/enzymology
- Brain Neoplasms/genetics
- Brain Neoplasms/pathology
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cell Line, Tumor
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Enzyme Activation
- Epidermal Growth Factor/metabolism
- ErbB Receptors/genetics
- ErbB Receptors/metabolism
- Female
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Neoplastic
- Genes, Reporter
- Glioblastoma/enzymology
- Glioblastoma/genetics
- Glioblastoma/pathology
- Glucose/metabolism
- Glycolysis
- HEK293 Cells
- Heterogeneous-Nuclear Ribonucleoproteins/metabolism
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- I-kappa B Kinase/metabolism
- Lactic Acid/metabolism
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice
- Mice, Nude
- Mutagenesis, Site-Directed
- Mutation
- NF-kappa B/genetics
- NF-kappa B/metabolism
- Neoplasm Grading
- Neoplasm Transplantation
- Phospholipase C gamma/metabolism
- Phosphorylation
- Polypyrimidine Tract-Binding Protein/metabolism
- Prognosis
- Promoter Regions, Genetic
- Protein Kinase C-epsilon/genetics
- Protein Kinase C-epsilon/metabolism
- RNA Interference
- Serine
- Signal Transduction
- Thyroid Hormones/genetics
- Thyroid Hormones/metabolism
- Transcription Factor RelA/metabolism
- Transfection
- Ubiquitination
- Up-Regulation
- Thyroid Hormone-Binding Proteins
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Affiliation(s)
- Weiwei Yang
- Brain Tumor Center and Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Yan Xia
- Brain Tumor Center and Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Yu Cao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Yanhua Zheng
- Brain Tumor Center and Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Wen Bu
- Lester and Sue Smith Breast Center & Department of Molecular and Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lin Zhang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
| | - M. James You
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Mei Yee Koh
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Gilbert Cote
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Kenneth Aldape
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Yi Li
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Inder M. Verma
- Laboratory of Genetics and Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Paul J Chiao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Zhimin Lu
- Brain Tumor Center and Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
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26
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van Wijk SJL, Fiskin E, Putyrski M, Pampaloni F, Hou J, Wild P, Kensche T, Grecco HE, Bastiaens P, Dikic I. Fluorescence-based sensors to monitor localization and functions of linear and K63-linked ubiquitin chains in cells. Mol Cell 2012; 47:797-809. [PMID: 22819327 DOI: 10.1016/j.molcel.2012.06.017] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/02/2012] [Accepted: 06/12/2012] [Indexed: 10/28/2022]
Abstract
Ubiquitin chains modify a major subset of the proteome, but detection of ubiquitin signaling dynamics and localization is limited due to a lack of appropriate tools. Here, we employ ubiquitin-binding domain (UBD)-based fluorescent sensors to monitor linear and K63-linked chains in vitro and in vivo. We utilize the UBD in NEMO and ABIN (UBAN) for detection of linear chains, and RAP80 ubiquitin-interacting motif (UIM) and TAB2 Npl4 zinc finger (NZF) domains to detect K63 chains. Linear and K63 sensors decorated the ubiquitin coat surrounding cytosolic Salmonella during bacterial autophagy, whereas K63 sensors selectively monitored Parkin-induced mitophagy and DNA damage responses in fixed and living cells. In addition, linear and K63 sensors could be used to monitor endogenous signaling pathways, as demonstrated by their ability to differentially interfere with TNF- and IL-1-induced NF-κB pathway. We propose that UBD-based biosensors could serve as prototypes to track and trace other chain types and ubiquitin-like signals in vivo.
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Affiliation(s)
- Sjoerd J L van Wijk
- Institute of Biochemistry II, Goethe University School of Medicine, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
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27
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Tokunaga F, Iwai K. LUBAC, a novel ubiquitin ligase for linear ubiquitination, is crucial for inflammation and immune responses. Microbes Infect 2012; 14:563-72. [DOI: 10.1016/j.micinf.2012.01.011] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 01/19/2012] [Indexed: 10/14/2022]
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28
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Emmerich CH, Schmukle AC, Walczak H. The Emerging Role of Linear Ubiquitination in Cell Signaling. Sci Signal 2011; 4:re5. [DOI: 10.1126/scisignal.2002187] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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29
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Verhelst K, Verstrepen L, Carpentier I, Beyaert R. Linear ubiquitination in NF-κB signaling and inflammation: What we do understand and what we do not. Biochem Pharmacol 2011; 82:1057-65. [PMID: 21787758 DOI: 10.1016/j.bcp.2011.07.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/03/2011] [Accepted: 07/07/2011] [Indexed: 10/17/2022]
Abstract
Despite its small size, ubiquitin is one of the most versatile signaling molecules in the cell and affects distinct cellular processes. It forms the building block of a repertoire of posttranslational modifications of cellular proteins, ranging from the attachment of a single ubiquitin to ubiquitin chains of different linkage. Proteins that contain ubiquitin chain-specific ubiquitin-binding domains recognize different types of ubiquitination and determine the mode of signaling of modified proteins. Polyubiquitin chains were thought to be formed only by the conjugation of the ubiquitin C-terminal Gly to one of the seven internal Lys residues of another ubiquitin. However, the C-terminal Gly was recently shown to also link to the N-terminus of another ubiquitin to form head-to-tail polyubiquitin chains, which is referred to as linear ubiquitination. These linear linkages can be assembled and conjugated to another protein by an E3 ligase complex known as LUBAC, and are recognized by a particular ubiquitin-binding domain known as UBAN. Both have been implicated in the regulation of TNF-induced NF-κB signaling, which induces the expression of a wide range of proteins that mediate many biological processes including inflammation and cell survival. We discuss the molecular players and mechanisms that determine the specificity and outcome of linear ubiquitination in NF-κB signaling, as well as future directions and challenges ahead.
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Affiliation(s)
- Kelly Verhelst
- Department for Molecular Biomedical Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium
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30
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Suzuki T, Hara H. Phytate hydrolysate induces circumferential F-actin ring formation at cell-cell contacts by a Rho-associated kinase-dependent mechanism in colorectal cancer HT-29 cells. Mol Nutr Food Res 2010; 54:1807-18. [DOI: 10.1002/mnfr.200900606] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Sipl1 and Rbck1 are novel Eya1-binding proteins with a role in craniofacial development. Mol Cell Biol 2010; 30:5764-75. [PMID: 20956555 DOI: 10.1128/mcb.01645-09] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The eyes absent 1 protein (Eya1) plays an essential role in the development of various organs in both invertebrates and vertebrates. Mutations in the human EYA1 gene are linked to BOR (branchio-oto-renal) syndrome, characterized by kidney defects, hearing loss, and branchial arch anomalies. For a better understanding of Eya1's function, we have set out to identify new Eya1-interacting proteins. Here we report the identification of the related proteins Sipl1 (Shank-interacting protein-like 1) and Rbck1 (RBCC protein interacting with PKC1) as novel interaction partners of Eya1. We confirmed the interactions by glutathione S-transferase (GST) pulldown analysis and coimmunoprecipitation. A first mechanistic insight is provided by the demonstration that Sipl1 and Rbck1 enhance the function of Eya proteins to act as coactivators for the Six transcription factors. Using reverse transcriptase PCR (RT-PCR) and in situ hybridization, we show that Sipl1 and Rbck1 are coexpressed with Eya1 in several organs during embryogenesis of both the mouse and zebrafish. By morpholino-mediated knockdown, we demonstrate that the Sipl1 and Rbck1 orthologs are involved in different aspects of zebrafish development. In particular, knockdown of one Sipl1 ortholog as well as one Rbck1 ortholog led to a BOR syndrome-like phenotype, with characteristic defects in ear and branchial arch formation.
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Gautheron J, Courtois G. "Without Ub I am nothing": NEMO as a multifunctional player in ubiquitin-mediated control of NF-kappaB activation. Cell Mol Life Sci 2010; 67:3101-13. [PMID: 20502939 PMCID: PMC11115954 DOI: 10.1007/s00018-010-0404-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/06/2010] [Accepted: 05/07/2010] [Indexed: 11/26/2022]
Abstract
Ubiquitination has emerged over the years as the most sophisticated way to modify proteins to affect their fate and function. In particular, it has been reported to be instrumental in regulating several steps of the NF-kappaB signalling pathway which controls inflammation, immunity, adhesion and cell survival. Integrating ubiquitination into NF-kappaB activation requires the regulatory subunit of IKK, NEMO, which not only displays affinity for polyubiquitin chains, but is also posttranslationally modified by a complex set of reactions involving ubiquitin. Here, we examine how studies of the NEMO/ubiquitin relationship have provided novel insights into the IKK activation process and have uncovered molecular mechanisms that should represent in the future attractive targets for specifically modulating NF-kappaB function.
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Affiliation(s)
- Jérémie Gautheron
- INSERM U781, Tour Lavoisier, Hôpital Necker-Enfants Malades and Université Paris-Descartes, 149, rue de Sèvres, 75015 Paris, France
| | - Gilles Courtois
- INSERM U781, Tour Lavoisier, Hôpital Necker-Enfants Malades and Université Paris-Descartes, 149, rue de Sèvres, 75015 Paris, France
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Eldridge AG, O'Brien T. Therapeutic strategies within the ubiquitin proteasome system. Cell Death Differ 2010; 17:4-13. [PMID: 19557013 DOI: 10.1038/cdd.2009.82] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The ubiquitin-dependent proteolysis system (UPS) is the main driver of regulated protein degradation in all eukaryotic cells, and it is becoming increasingly clear that defects within this pathway drive a large number of human pathologies. Recent success in the use of proteasome inhibitors in the treatment of hematological malignancies validates the UPS as a viable therapeutic pathway, and substantial effort is now focused on the development of both second-generation proteasome inhibitors as well as novel strategies for the inhibition of upstream UPS enzymes. In this review we discuss the potential 'druggability' of key nodes within the UPS and summarize recent advances within the field.
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Affiliation(s)
- A G Eldridge
- Department of Cell Regulation, Genentech Inc., South San Francisco, CA 94080, USA.
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Functions of Linear Ubiquitin Chains in the NF-κB Pathway : Linear Polyubiquitin in NF-κB Signaling. Subcell Biochem 2010; 54:100-6. [PMID: 21222276 DOI: 10.1007/978-1-4419-6676-6_8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The ubiquitin conjugation system regulates a wide variety of biological phenomena, in most cases, by modulating protein function via polyubiquitin conjugation. Several types of polyubiquitin chains exist in cells and the type of chain conjugated to a protein seems to determine how the protein is regulated. The polyubiquitin chains that have been reported thus far are generated by conjugation via Lys residues of ubiquitin. We have identified a novel linear polyubiquitin chain, in which the C-terminal Gly of one ubiquitin is conjugated to the α-amino group of the N-terminal Met of another ubiquitin and the ubiquitin ligase complex mediating these reactions specifically generates linear chains. We have shown that linear polyubiquitination is involved in activation of the canonical NF-κB pathway. The regulatory roles of Lys63-linked ubiquitin chains in the NF-κB path way have been extensively studied. In this chapter, we will discuss the distinct roles of linear and K63-linked ubiquitin chains in TNF-α mediated NF-κB activation and the future directions for linear ubiquitin chain research.
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The ubiquitin proteasome system and its involvement in cell death pathways. Cell Death Differ 2009; 17:1-3. [PMID: 20010850 DOI: 10.1038/cdd.2009.189] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Abstract
Protein kinases are important regulators of intracellular signal transduction pathways and play critical roles in diverse cellular functions. Once a protein kinase is activated, its activity is subsequently downregulated through a variety of mechanisms. Accumulating evidence indicates that the activation of protein kinases commonly initiates their downregulation via the ubiquitin/proteasome pathway. Failure to regulate protein kinase activity or expression levels can cause human diseases.
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Affiliation(s)
- Zhimin Lu
- Department of Neuro-Oncology and Molecular and Cellular Oncology, University of Texas M. D. Anderson Cancer, Houston, TX 77030, USA.
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Linear polyubiquitination: a new regulator of NF-kappaB activation. EMBO Rep 2009; 10:706-13. [PMID: 19543231 DOI: 10.1038/embor.2009.144] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Accepted: 05/25/2009] [Indexed: 11/08/2022] Open
Abstract
The ubiquitin-conjugation system regulates a vast range of biological phenomena by affecting protein function mostly through polyubiquitin conjugation. The type of polyubiquitin chain that is generated seems to determine how conjugated proteins are regulated, as they are recognized specifically by proteins that contain chain-specific ubiquitin-binding motifs. An enzyme complex that catalyses the formation of newly described linear polyubiquitin chains--known as linear ubiquitin chain-assembly complex (LUBAC)--has recently been characterized, as has a particular ubiquitin-binding domain that specifically recognizes linear chains. Both have been shown to have crucial roles in the canonical nuclear factor-kappaB (NF-kappaB)-activation pathway. The ubiquitin system is intimately involved in regulating the NF-kappaB pathway, and the regulatory roles of K63-linked chains have been studied extensively. However, the role of linear chains in this process is only now emerging. This article discusses the possible mechanisms underlying linear polyubiquitin-mediated activation of NF-kappaB, and the different roles that K63-linked and linear chains have in NF-kappaB activation. Future directions for linear polyubiquitin research are also discussed.
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New ATPase regulators--p97 goes to the PUB. Int J Biochem Cell Biol 2009; 41:2380-8. [PMID: 19497384 DOI: 10.1016/j.biocel.2009.05.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/26/2009] [Accepted: 05/26/2009] [Indexed: 01/10/2023]
Abstract
The conserved eukaryotic AAA-type ATPase complex, known as p97 or VCP in mammals and Cdc48 in yeast, is involved in a number of cellular pathways, including fusion of homotypic membranes, protein degradation, and activation of membrane-bound transcription factors. Most likely, p97 is directed to this broad spectrum of cellular functions through its binding to specific cofactors. More than 20 different p97 cofactors have been described to date and our understanding of their cellular functions is rapidly expanding. Common to these proteins is their intimate connection with the ubiquitin system. Recently, a small, conserved family of proteins, containing PUB domains, was found to function as p97 adaptors. Intriguingly, their association with p97 is regulated by tyrosine phosphorylation, suggesting that they act as a relay between signalling pathways and p97 functions. Here we give an overview of the currently known PUB-domain proteins and other p97-interacting proteins.
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Tokunaga F, Sakata SI, Saeki Y, Satomi Y, Kirisako T, Kamei K, Nakagawa T, Kato M, Murata S, Yamaoka S, Yamamoto M, Akira S, Takao T, Tanaka K, Iwai K. Involvement of linear polyubiquitylation of NEMO in NF-kappaB activation. Nat Cell Biol 2009; 11:123-32. [PMID: 19136968 DOI: 10.1038/ncb1821] [Citation(s) in RCA: 769] [Impact Index Per Article: 51.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Accepted: 10/14/2008] [Indexed: 11/09/2022]
Abstract
Nuclear factor-kappaB (NF-kappaB) is a key transcription factor in inflammatory, anti-apoptotic and immune processes. The ubiquitin pathway is crucial in regulating the NF-kappaB pathway. We have found that the LUBAC ligase complex, composed of the two RING finger proteins HOIL-1L and HOIP, conjugates a head-to-tail-linked linear polyubiquitin chain to substrates. Here, we demonstrate that LUBAC activates the canonical NF-kappaB pathway by binding to NEMO (NF-kappaB essential modulator, also called IKKgamma) and conjugates linear polyubiquitin chains onto specific Lys residues in the CC2-LZ domain of NEMO in a Ubc13-independent manner. Moreover, in HOIL-1 knockout mice and cells derived from these mice, NF-kappaB signalling induced by pro-inflammatory cytokines such as TNF-alpha and IL-1beta was suppressed, resulting in enhanced TNF-alpha-induced apoptosis in hepatocytes of HOIL-1 knockout mice. These results indicate that LUBAC is involved in the physiological regulation of the canonical NF-kappaB activation pathway through linear polyubiquitylation of NEMO.
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Affiliation(s)
- Fuminori Tokunaga
- Department of Biophysics and Biochemistry, Graduate School of Medicine and Cell Biology and Metabolism Group, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
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Abstract
Protein kinase C (PKC) is a family of kinases that plays diverse roles in many cellular functions, notably proliferation, differentiation, and cell survival. PKC is processed by phosphorylation and regulated by cofactor binding and subcellular localization. Extensive detail is available on the molecular mechanisms that regulate the maturation, activation, and signaling of PKC. However, less information is available on how signaling is terminated both from a global perspective and isozyme-specific differences. To target PKC therapeutically, various ATP-competitive inhibitors have been developed, but this method has problems with specificity. One possible new approach to developing novel, specific therapeutics for PKC would be to target the signaling termination pathways of the enzyme. This review focuses on the new developments in understanding how PKC signaling is terminated and how current drug therapies as well as information obtained from the recent elucidation of various PKC structures and down-regulation pathways could be used to develop novel and specific therapeutics for PKC.
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Affiliation(s)
- Christine M. Gould
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093-0721
| | - Alexandra C. Newton
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093-0721
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