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Penthala NR, Balasubramaniam M, Dachavaram SS, Morris EJ, Bhat-Nakshatri P, Ponder J, Jordan CT, Nakshatri H, Crooks PA. Antitumor properties of novel sesquiterpene lactone analogs as NFκB inhibitors that bind to the IKKβ ubiquitin-like domain (ULD). Eur J Med Chem 2021; 224:113675. [PMID: 34229108 DOI: 10.1016/j.ejmech.2021.113675] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 11/30/2022]
Abstract
Melampomagnolide B (MMB, 3) is a parthenolide (PTL, 1) based sesquiterpene lactone that has been used as a template for the synthesis of a plethora of lead anticancer agents owing to its reactive C-10 primary hydroxyl group. Such compounds have been shown to inhibit the IKKβ subunit, preventing phosphorylation of the cytoplasmic IκB inhibitory complex. The present study focuses on the synthesis and in vitro antitumor properties of novel benzyl and phenethyl carbamates of MMB (7a-7k). Screening of these MMB carbamates identified analogs with potent growth inhibition properties against a panel of 60 human cancer cell lines (71% of the molecules screened had GI50 values < 2 μM). Two analogs, the benzyl carbamate 7b and the phenethyl carbamate7k, were the most active compounds. Lead compound 7b inhibited cell proliferation in M9 ENL AML cells, and in TMD-231, OV-MD-231 and SUM149 breast cancer cell lines. Interestingly, mechanistic studies showed that 7b did not inhibit p65 phosphorylation in M9 ENL AML and OV-MD-231 cells, but did inhibit phophorylation of both p65 and IκBα in SUM149 cells. 7b also reduced NFκB binding to DNA in both OV-MD-231 and SUM149 cells. Molecular docking studies indicated that 7b and 7k are both predicted to interact with the ubiquitin-like domain (ULD) of the IKKβ subunit. These data suggest that in SUM149 cells, 7b is likely acting as an allosteric inhibitor of IKKβ, whereas in M9 ENL AML and OV-MD-231 cells 7b is able to inhibit an event after IκB/p65/p50 phosphorylation by IKKβ that leads to inhibition of NFκB activation and reduction in NFκB-DNA binding. Analog 7b was by far the most potent compound in either carbamate series, and was considered an important lead compound for further optimization and development as an anticancer agent.
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Affiliation(s)
- Narsimha R Penthala
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, United States
| | - Meenakshisundaram Balasubramaniam
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, United States
| | - Soma Shekar Dachavaram
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, United States
| | - Earl J Morris
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, United States
| | - Poornima Bhat-Nakshatri
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, United States
| | - Jessica Ponder
- Division of Hematology and University of Colorado, Aurora, CO, 80045, United States
| | - Craig T Jordan
- Division of Hematology and University of Colorado, Aurora, CO, 80045, United States
| | - Harikrishna Nakshatri
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, United States
| | - Peter A Crooks
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, United States.
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2
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Triptolide dysregulates glucose uptake via inhibition of IKKβ-NF-κB pathway by p53 activation in cardiomyocytes. Toxicol Lett 2020; 318:1-11. [DOI: 10.1016/j.toxlet.2019.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/05/2019] [Accepted: 10/08/2019] [Indexed: 02/08/2023]
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3
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Scofield SLC, Amin P, Singh M, Singh K. Extracellular Ubiquitin: Role in Myocyte Apoptosis and Myocardial Remodeling. Compr Physiol 2015; 6:527-60. [PMID: 26756642 DOI: 10.1002/cphy.c150025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ubiquitin (UB) is a highly conserved low molecular weight (8.5 kDa) protein. It consists of 76 amino acid residues and is found in all eukaryotic cells. The covalent linkage of UB to a variety of cellular proteins (ubiquitination) is one of the most common posttranslational modifications in eukaryotic cells. This modification generally regulates protein turnover and protects the cells from damaged or misfolded proteins. The polyubiquitination of proteins serves as a signal for degradation via the 26S proteasome pathway. UB is present in trace amounts in body fluids. Elevated levels of UB are described in the serum or plasma of patients under a variety of conditions. Extracellular UB is proposed to have pleiotropic roles including regulation of immune response, anti-inflammatory, and neuroprotective activities. CXCR4 is identified as receptor for extracellular UB in hematopoietic cells. Heart failure represents a major cause of morbidity and mortality in western society. Cardiac remodeling is a determinant of the clinical course of heart failure. The components involved in myocardial remodeling include-myocytes, fibroblasts, interstitium, and coronary vasculature. Increased sympathetic nerve activity in the form of norepinephrine is a common feature during heart failure. Acting via β-adrenergic receptor (β-AR), norepinephrine is shown to induce myocyte apoptosis and myocardial fibrosis. β-AR stimulation increases extracellular levels of UB in myocytes, and UB inhibits β-AR-stimulated increases in myocyte apoptosis and myocardial fibrosis. This review summarizes intracellular and extracellular functions of UB with particular emphasis on the role of extracellular UB in cardiac myocyte apoptosis and myocardial remodeling.
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Affiliation(s)
- Stephanie L C Scofield
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee, USA
| | - Parthiv Amin
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee, USA
| | - Mahipal Singh
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee, USA
| | - Krishna Singh
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee, USA; Center for Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee, USA; James H. Quillen VA Medical Center, East Tennessee State University, Johnson City, Tennessee, USA.,Department of Medicine, Albany Medical College, Albany, New York, USA.,Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, Rensselaer, New York, USA
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4
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Regulation of HTLV-1 tax stability, cellular trafficking and NF-κB activation by the ubiquitin-proteasome pathway. Viruses 2014; 6:3925-43. [PMID: 25341660 PMCID: PMC4213571 DOI: 10.3390/v6103925] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 12/22/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is a complex retrovirus that infects CD4+ T cells and causes adult T-cell leukemia/lymphoma (ATLL) in 3%–5% of infected individuals after a long latent period. HTLV-1 Tax is a trans-activating protein that regulates viral gene expression and also modulates cellular signaling pathways to enhance T-cell proliferation and cell survival. The Tax oncoprotein promotes T-cell transformation, in part via constitutive activation of the NF-κB transcription factor; however, the underlying mechanisms remain unknown. Ubiquitination is a type of post-translational modification that occurs in a three-step enzymatic cascade mediated by E1, E2 and E3 enzymes and regulates protein stability as well as signal transduction, protein trafficking and the DNA damage response. Emerging studies indicate that Tax hijacks the ubiquitin machinery to activate ubiquitin-dependent kinases and downstream NF-κB signaling. Tax interacts with the E2 conjugating enzyme Ubc13 and is conjugated on C-terminal lysine residues with lysine 63-linked polyubiquitin chains. Tax K63-linked polyubiquitination may serve as a platform for signaling complexes since this modification is critical for interactions with NEMO and IKK. In addition to NF-κB signaling, mono- and polyubiquitination of Tax also regulate its subcellular trafficking and stability. Here, we review recent advances in the diverse roles of ubiquitin in Tax function and how Tax usurps the ubiquitin-proteasome pathway to promote oncogenesis.
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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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6
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Zhang Y, Otero JE, Abu-Amer Y. Ubiquitin-like domain of IKKβ regulates osteoclastogenesis and osteolysis. Calcif Tissue Int 2013; 93:78-85. [PMID: 23686246 PMCID: PMC3706195 DOI: 10.1007/s00223-013-9735-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/19/2013] [Indexed: 01/01/2023]
Abstract
The transcription factor NF-κB family is central for osteoclastogenesis and inflammatory osteolysis. Activation of NF-κB dimers is regulated by a kinase complex predominantly containing IKKα (IKK1), IKKβ (IKK2), and a regulatory subunit, IKKγ/NEMO. IKKα and IKKβ catalyze the cytoplasmic liberation and nuclear translocation of various NF-κB subunits. The requirement of IKKα and IKKβ for normal bone homeostasis has been established. Congruently, mice devoid of IKKα or IKKβ exhibit in vitro and in vivo defects in osteoclastogenesis, and IKKβ-null mice are refractory to inflammatory arthritis and osteolysis. To better understand the molecular mechanism underlying IKKβ function in bone homeostasis and bone pathologies, we conducted structure-function analysis to determine IKKβ functional domains in osteoclasts. IKKβ encompasses several domains, of which the ubiquitination-like domain (ULD) has been shown essential for IKKβ activation. In this study, we examined the role of ULD in IKKβ-mediated NF-κB activation in osteoclast precursors and its contribution to osteoclastogenesis and osteolysis. We generated and virally introduced IKKβ in which the ULD domain has been deleted (IKKβ∆ULD) into osteoclast progenitors. The results show that deletion of ULD diminishes IKKβ activity and that IKKβ∆ULD strongly inhibits osteoclastogenesis. In addition, unlike wild type (WT)-IKKβ, IKKβ∆ULD fail to restore RANKL-induced osteoclastogenesis by IKKβ-null precursors. Finally, we provide evidence that IKKβ∆ULD blocks inflammatory osteolysis in a model of murine calvarial osteolysis. Thus, we identified the ULD as crucial for IKKβ activity and osteoclastogenesis and found that ULD-deficient IKKβ is a potent inhibitor of osteoclastogenesis and osteolysis.
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Affiliation(s)
- Yanhong Zhang
- Department of Orthopaedic Surgery and Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Medicine, Raritan Bay Medical Center, 530 New Brunswick Ave, Perth Amboy, NJ 08861
| | - Jesse E. Otero
- University of Iowa Hospitals and Clinics, Department of Orthopaedic Surgery, Iowa City, Iowa 52242
| | - Yousef Abu-Amer
- Department of Orthopaedic Surgery and Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110
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7
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Currer R, Van Duyne R, Jaworski E, Guendel I, Sampey G, Das R, Narayanan A, Kashanchi F. HTLV tax: a fascinating multifunctional co-regulator of viral and cellular pathways. Front Microbiol 2012; 3:406. [PMID: 23226145 PMCID: PMC3510432 DOI: 10.3389/fmicb.2012.00406] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 11/12/2012] [Indexed: 12/18/2022] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) has been identified as the causative agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The virus infects between 15 and 20 million people worldwide of which approximately 2-5% develop ATL. The past 35 years of research have yielded significant insight into the pathogenesis of HTLV-1, including the molecular characterization of Tax, the viral transactivator, and oncoprotein. In spite of these efforts, the mechanisms of oncogenesis of this pleiotropic protein remain to be fully elucidated. In this review, we illustrate the multiple oncogenic roles of Tax by summarizing a recent body of literature that refines our understanding of cellular transformation. A focused range of topics are discussed in this review including Tax-mediated regulation of the viral promoter and other cellular pathways, particularly the connection of the NF-κB pathway to both post-translational modifications (PTMs) of Tax and subcellular localization. Specifically, recent research on polyubiquitination of Tax as it relates to the activation of the IkappaB kinase (IKK) complex is highlighted. Regulation of the cell cycle and DNA damage responses due to Tax are also discussed, including Tax interaction with minichromosome maintenance proteins and the role of Tax in chromatin remodeling. The recent identification of HTLV-3 has amplified the importance of the characterization of emerging viral pathogens. The challenge of the molecular determination of pathogenicity and malignant disease of this virus lies in the comparison of the viral transactivators of HTLV-1, -2, and -3 in terms of transformation and immortalization. Consequently, differences between the three proteins are currently being studied to determine what factors are required for the differences in tumorogenesis.
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Affiliation(s)
- Robert Currer
- National Center for Biodefense and Infectious Diseases, George Mason University Manassas, VA, USA
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Fan Y, Shi Y, Liu S, Mao R, An L, Zhao Y, Zhang H, Zhang F, Xu G, Qin J, Yang J. Lys48-linked TAK1 polyubiquitination at lysine-72 downregulates TNFα-induced NF-κB activation via mediating TAK1 degradation. Cell Signal 2012; 24:1381-9. [PMID: 22406003 PMCID: PMC3580185 DOI: 10.1016/j.cellsig.2012.02.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/30/2012] [Accepted: 02/22/2012] [Indexed: 01/06/2023]
Abstract
Protein kinases are important regulators of intracellular signal transduction pathways and play critical roles in diverse cellular processes. TAK1, a member of the MAPKKK family, is essential for TNFα-induced NF-κB activation. Phosphorylation and Lys(63)-linked polyubiquitination (polyUb) of TAK1 are critical for its activation. However, whether TAK1 is regulated by polyubiquitination-mediated protein degradation after its activation remains unknown. Here we report that TNFα induces TAK1 Lys(48) linked polyubiquitination and degradation at the later time course. Furthermore, we provide direct evidence that TAK1 is modified by Lys(48)-linked polyubiquitination at lysine-72 by mass spectrometry. A K72R point mutation on TAK1 abolishes TAK1 Lys(48)-linked polyubiquitination and enhances TAK1/TAB1 co-overexpression-induced NF-κB activation. As expected, TAK1 K72R mutation inhibits TNFα-induced Lys(48)-linked TAK1 polyubiquitination and degradation. TAK1 K72R mutant prolongs TNFα-induced NF-κB activation and enhances TNFα-induced IL-6 gene expression. Our findings demonstrate that TNFα induces Lys(48)-linked polyubiquitination of TAK1 at lysine-72 and this polyubiquitination-mediated TAK1 degradation plays a critical role in the downregulation of TNFα-induced NF-κB activation.
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Affiliation(s)
- Yihui Fan
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030
| | - Yi Shi
- Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Shangfeng Liu
- Translational Center for Stem Cell Research, Tongji Hospital, Shanghai, China 200065
- Stem Cell Research Center and Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China 200092
| | - Renfang Mao
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030
| | - Lei An
- Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, TX 77030
| | - Yanling Zhao
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030
| | - Hong Zhang
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030
- Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, TX 77030
| | - Fuchun Zhang
- Key Laboratory of Molecular Biology, College of Life Science and Technology, Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, Xinjiang University, Urumqi, China 830046
| | - Guotong Xu
- Stem Cell Research Center and Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China 200092
- Department of Ophthalmology, Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China 200092
| | - Jun Qin
- Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Jianhua Yang
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030
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9
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Huang WC, Chen WS, Chen YJ, Wang LY, Hsu SC, Chen CC, Hung MC. Hepatitis B virus X protein induces IKKα nuclear translocation via Akt-dependent phosphorylation to promote the motility of hepatocarcinoma cells. J Cell Physiol 2012; 227:1446-54. [PMID: 21618535 DOI: 10.1002/jcp.22860] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hepatitis B virus (HBV) X protein (HBx) has been implicated in HBV-associated carcinogenesis through activation of IκB kinase (IKK)/nuclear factor kappa B (NF-κB) signaling pathway. Besides activating NF-κB in the cytoplasm, IKKα was found in the nucleus to regulate gene expression epigenetically in response to various stimuli. However, it is unknown whether nuclear IKKα plays a role in HBx-associated tumor progression. Moreover, the molecular mechanism underlying IKKα nuclear transport also remains to be elucidated. Here, we disclosed HBx as a new inducer of IKKα nuclear transport in hepatoma cells. HBx induced IKKα nuclear transport in an Akt-dependent manner. HBx-activated Akt promoted IKKα nuclear translocation via phosphorylating its threonine-23 (Thr23). In addition, IKKα ubiquitination enhanced by HBx and Akt also contributed to the IKKα accumulation in the nucleus, indicating the involvement of ubiquitination in Akt-increased IKKα nuclear transport in response to HBx. Furthermore, inhibition of IKKα nuclear translocation by mutation of its nuclear localization signal and Thr23 diminished IKKα-dependent cell migration. Taken together, our findings shed light on the molecular mechanism of IKKα nuclear translocation and provide a potential role of nuclear IKKα in HBx-mediated hepatocellular carcinoma (HCC) progression.
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Affiliation(s)
- Wei-Chien Huang
- Graduate Institute of Cancer Biology, China Medical University and Hospital, Taichung, Taiwan.
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10
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Curcumin treatment prevents increased proteasome and apoptosome activities in rat skeletal muscle during reloading and improves subsequent recovery. J Nutr Biochem 2012; 23:245-51. [DOI: 10.1016/j.jnutbio.2010.11.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 10/20/2010] [Accepted: 11/29/2010] [Indexed: 11/22/2022]
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11
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Perrett CA, Lin DYW, Zhou D. Interactions of bacterial proteins with host eukaryotic ubiquitin pathways. Front Microbiol 2011; 2:143. [PMID: 21772834 PMCID: PMC3131157 DOI: 10.3389/fmicb.2011.00143] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/16/2011] [Indexed: 12/20/2022] Open
Abstract
Ubiquitination is a post-translational modification in which one or more 76 amino acid polypeptide ubiquitin molecules are covalently linked to the lysine residues of target proteins. Ubiquitination is the main pathway for protein degradation that governs a variety of eukaryotic cellular processes, including the cell-cycle, vesicle trafficking, antigen presentation, and signal transduction. Not surprisingly, aberrations in the system have been implicated in the pathogenesis of many diseases including inflammatory and neurodegenerative disorders. Recent studies have revealed that viruses and bacterial pathogens exploit the host ubiquitination pathways to gain entry and to aid their survival/replication inside host cells. This review will summarize recent developments in understanding the biochemical and structural mechanisms utilized by bacterial pathogens to interact with the host ubiquitination pathways.
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Affiliation(s)
| | - David Yin-Wei Lin
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
| | - Daoguo Zhou
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
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12
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Abstract
NF-κB is a pivotal transcription factor that controls cell survival and proliferation in diverse physiological processes. The activity of NF-κB is tightly controlled through its cytoplasmic sequestration by specific inhibitors, IκBs. Various cellular stimuli induce the activation of an IκB kinase, which phosphorylates IκBs and triggers their proteasomal degradation, causing nuclear translocation of activated NF-κB. Under normal conditions, the activation of NF-κB occurs transiently, thus ensuring rapid but temporary induction of target genes. Deregulated NF-κB activation contributes to the development of various diseases, including cancers and immunological disorders. Accumulated studies demonstrate that the NF-κB signaling pathway is a target of several human oncogenic viruses, including the human T cell leukemia virus type 1, the Kaposi sarcoma-associated herpesvirus, and the Epstein-Bar virus. These viruses encode specific oncoproteins that target different signaling components of the NF-κB pathway, leading to persistent activation of NF-κB. This chapter will discuss the molecular mechanisms by which NF-κB is activated by the viral oncoproteins.
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Affiliation(s)
- Shao-Cong Sun
- Department of Immunology, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, 1300 York Ave, New York, NY 10065
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Niida M, Tanaka M, Kamitani T. Downregulation of active IKK beta by Ro52-mediated autophagy. Mol Immunol 2010; 47:2378-87. [PMID: 20627395 PMCID: PMC2918734 DOI: 10.1016/j.molimm.2010.05.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 05/05/2010] [Indexed: 01/20/2023]
Abstract
Upon activation, NF-kappaB translocates into the nucleus and initiates many biological events. This NF-kappaB signaling is mainly induced by the protein kinase IKK beta. Early in this signaling pathway, IKK beta is phosphorylated for activation by several factors, such as pro-inflammatory cytokines and the Tax oncoprotein of human T-cell leukemia virus type 1 (HTLV-1). In cells expressing Tax protein, IKK beta is persistently phosphorylated, which chronically activates NF-kappaB signaling. But the active IKK beta is conjugated with a monoubiquitin by the E3 ubiquitin ligase Ro52, and the IKK beta-induced NF-kappaB signaling is downregulated. However, the mechanism of the downregulation has been unknown. Here, we show that Ro52-mediated monoubiquitination is involved in the subcellular translocation of active IKK beta to autophagosomes. Furthermore, using reporter assays, we show that Ro52 suppresses IKK beta-induced NF-kappaB signaling and that this suppression is blocked by an autophagy inhibitor. These results suggest that Ro52-mediated monoubiquitination plays a critical role in the downregulation of active IKK beta through autophagy.
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Affiliation(s)
- Motoko Niida
- Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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Gan Q, Li T, Hu B, Lian M, Zheng X. HSCARG inhibits activation of NF-κB by interacting with IκB kinase-β. J Cell Sci 2009; 122:4081-8. [DOI: 10.1242/jcs.054007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
HSCARG is a recently identified human NADPH sensor. Our previous studies have shown that HSCARG can affect NO production and cell viability, but the signal pathway mediated by this protein is unknown. Here, we show that HSCARG is involved in the NF-κB signaling pathway and find that HSCARG suppresses TNF- and IL1-induced NF-κB activation in a dose-dependent manner. Co-immunoprecipitation and immunofluorescence analyses demonstrate that HSCARG interacts and colocalizes with IKKβ. HSCARG inhibits the phosphorylation of IKKβ and further blocks the degradation of IκBα, the substrate of IKKβ, which retains NF-κB in the cytoplasm and suppresses its activity. In addition, our data indicate that IKKβ is required for HSCARG-inhibited NF-κB activation. Our findings delineate a pathway by which HSCARG negatively regulates NF-κB activation.
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Affiliation(s)
- Qini Gan
- National Laboratory of Protein Engineering and Plant Genetic Engineering, Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Tingting Li
- National Laboratory of Protein Engineering and Plant Genetic Engineering, Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Bin Hu
- National Laboratory of Protein Engineering and Plant Genetic Engineering, Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Min Lian
- National Laboratory of Protein Engineering and Plant Genetic Engineering, Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Xiaofeng Zheng
- National Laboratory of Protein Engineering and Plant Genetic Engineering, Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871, China
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15
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Wada K, Niida M, Tanaka M, Kamitani T. Ro52-mediated monoubiquitination of IKK{beta} down-regulates NF-{kappa}B signalling. J Biochem 2009; 146:821-32. [PMID: 19675099 DOI: 10.1093/jb/mvp127] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Upon activation, NF-kappaB translocates into the nucleus and initiates biological events. This NF-kappaB signalling is mainly regulated by the protein kinase IKKbeta. Early in this signalling pathway, IKKbeta is phosphorylated for activation by several factors, such as pro-inflammatory cytokines and the Tax oncoprotein of HTLV-1. In cells infected by HTLV-1, IKKbeta is persistently phosphorylated and conjugated with monoubiquitin due to Tax expression. Although this Tax-induced monoubiquitination appears to be an important regulation system for IKKbeta, how the monoubiquitination occurs is unknown and its role in NF-kappaB signalling is still unclear. Here, we show that an E3-ubiquitin ligase Ro52 interacts weakly with wild-type IKKbeta but strongly with a phosphomimetic mutant IKKbeta to conjugate monoubiquitin in cooperation with an E2-ubiquitin-conjugating enzyme UbcH5B. These results suggest that the Tax-induced phosphorylation of IKKbeta causes an interaction with Ro52 for the subsequent monoubiquitination. NF-kappaB reporter assays have shown that the IKKbeta activity is suppressed by wild-type Ro52, but not by its inactive mutant. In addition, monoubiquitin fusion of IKKbeta reduced its activity for NF-kappaB signalling. We also found that Ro52 dramatically reduces the level of Tax. These results suggest that Ro52 down-regulates Tax-induced NF-kappaB signalling by monoubiquitinating IKKbeta and by reducing the level of Tax.
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Affiliation(s)
- Keiji Wada
- Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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16
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Coiras M, Camafeita E, López-Huertas MR, Calvo E, López JA, Alcamí J. Application of proteomics technology for analyzing the interactions between host cells and intracellular infectious agents. Proteomics 2008; 8:852-73. [PMID: 18297655 PMCID: PMC7167661 DOI: 10.1002/pmic.200700664] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Host–pathogen interactions involve protein expression changes within both the host and the pathogen. An understanding of the nature of these interactions provides insight into metabolic processes and critical regulatory events of the host cell as well as into the mechanisms of pathogenesis by infectious microorganisms. Pathogen exposure induces changes in host proteins at many functional levels including cell signaling pathways, protein degradation, cytokines and growth factor production, phagocytosis, apoptosis, and cytoskeletal rearrangement. Since proteins are responsible for the cell biological functions, pathogens have evolved to manipulate the host cell proteome to achieve optimal replication. Intracellular pathogens can also change their proteome to adapt to the host cell and escape from immune surveillance, or can incorporate cellular proteins to invade other cells. Given that the interactions of intracellular infectious agents with host cells are mainly at the protein level, proteomics is the most suitable tool for investigating these interactions. Proteomics is the systematic analysis of proteins, particularly their interactions, modifications, localization and functions, that permits the study of the association between pathogens with their host cells as well as complex interactions such as the host–vector–pathogen interplay. A review on the most relevant proteomic applications used in the study of host–pathogen interactions is presented.
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Affiliation(s)
- Mayte Coiras
- Unidad de Inmunopatología del SIDA, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
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17
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Shao F. Biochemical functions of Yersinia type III effectors. Curr Opin Microbiol 2008; 11:21-9. [PMID: 18299249 DOI: 10.1016/j.mib.2008.01.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 01/11/2008] [Accepted: 01/18/2008] [Indexed: 01/09/2023]
Abstract
Yersinia uses a type III secretion system (TTSS) to deliver six effector proteins into host cells. These six proteins harbor distinct activities that are mimicries of host functions but often have acquired unique biochemical features. The host targets for these effectors appear to be limited to a few key signaling components such as G proteins and kinases, whereas their models of action are diverse and sophisticated. The functions of these effectors are to subvert the host immune defense response, including alterations of the cytoskeleton structure, inhibition of phagocytic clearance, blockage of cytokine production, and induction of apoptosis. These effectors also interfere with communications between the innate and the adaptive immune response, thus aiding the establishment of a systemic infection.
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Affiliation(s)
- Feng Shao
- National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing, China.
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18
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Mukherjee S, Negi VS, Keitany G, Tanaka Y, Orth K. In vitro activation of the IkappaB kinase complex by human T-cell leukemia virus type-1 Tax. J Biol Chem 2008; 283:15127-33. [PMID: 18223255 DOI: 10.1074/jbc.m704831200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human T-cell leukemia virus type-I expresses Tax, a 40-kDa oncoprotein that activates IkappaB kinase (IKK), resulting in constitutive activation of NFkappaB. Herein, we have developed an in vitro signaling assay to analyze IKK complex activation by recombinant Tax. Using this assay in combination with reporter assays, we demonstrate that Tax-mediated activation of IKK is independent of phosphatases. We show that sustained activation of the Tax-mediated activation of the NFkappaB pathway is dependent on an intact Hsp90-IKK complex. By acetylating and thereby preventing activation of the IKK complex by the Yersinia effector YopJ, we demonstrate that Tax-mediated activation of the IKK complex requires a phosphorylation step. Our characterization of an in vitro signaling assay system for the mechanism of Tax-mediated activation of the IKK complex with a variety of mutants and inhibitors results in a working model for the biochemical mechanism of Tax-induced activation.
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Affiliation(s)
- Sohini Mukherjee
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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19
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Structural requirements for Yersinia YopJ inhibition of MAP kinase pathways. PLoS One 2008; 3:e1375. [PMID: 18167536 PMCID: PMC2147050 DOI: 10.1371/journal.pone.0001375] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 12/03/2007] [Indexed: 11/25/2022] Open
Abstract
MAPK signaling cascades are evolutionally conserved. The bacterial effector, YopJ, uses the unique activity of Ser/Thr acetylation to inhibit the activation of the MAPK kinase (MKK) and prevent activation by phosphorylation. YopJ is also able to block yeast MAPK signaling pathways using this mechanism. Based on these observations, we performed a genetic screen to isolate mutants in the yeast MKK, Pbs2, that suppress YopJ inhibition. One suppressor contains a mutation in a conserved tyrosine residue and bypasses YopJ inhibition by increasing the basal activity of Pbs2. Mutations on the hydrophobic face of the conserved G α-helix in the kinase domain prevent both binding and acetylation by YopJ. Corresponding mutants in human MKKs showed that they are conserved not only structurally, but also functionally. These studies reveal a conserved binding site found on the superfamily of MAPK kinases while providing insight into the molecular interactions required for YopJ inhibition.
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20
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Sweet CR, Conlon J, Golenbock DT, Goguen J, Silverman N. YopJ targets TRAF proteins to inhibit TLR-mediated NF-kappaB, MAPK and IRF3 signal transduction. Cell Microbiol 2007; 9:2700-15. [PMID: 17608743 DOI: 10.1111/j.1462-5822.2007.00990.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Yersinia pestis virulence factor YopJ is a potent inhibitor of the NF-kappaB and MAPK signalling pathways, however, its molecular mechanism and relevance to pathogenesis are the subject of much debate. In this report, we characterize the effects of this type III effector protein on bone fide signalling events downstream of Toll-like receptors (TLRs), critical sensors in innate immunity. YopJ inhibited TLR-mediated NF-kappaB and MAP kinase activation, as suggested by previous studies. In addition, induction of the TLR-mediated interferon response was blocked by YopJ, indicating that YopJ also inhibits IRF3 signalling. Examination of the NF-kappaB signalling pathway in detail suggested that YopJ acts at the level of TAK1 (MAP3K7) activation. Further studies revealed a YopJ-dependent decrease in the ubiquitination of TRAF3 and TRAF6. These data support the hypothesis that YopJ is a deubiquitinating protease that acts on TRAF proteins to prevent or remove the K63-polymerized ubiquitin conjugates required for signal transduction. Our data do not directly address the alternative hypothesis that YopJ is an acetyltransferase that acts on the activation loop of IKK and MKK proteins, but support the conclusion that the critical function of YopJ is to deubiquinate TRAF proteins.
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Affiliation(s)
- Charles R Sweet
- Division of Infectious Diseases and Immunology, Departments of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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21
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Angot A, Vergunst A, Genin S, Peeters N. Exploitation of eukaryotic ubiquitin signaling pathways by effectors translocated by bacterial type III and type IV secretion systems. PLoS Pathog 2007; 3:e3. [PMID: 17257058 PMCID: PMC1781473 DOI: 10.1371/journal.ppat.0030003] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The specific and covalent addition of ubiquitin to proteins, known as ubiquitination, is a eukaryotic-specific modification central to many cellular processes, such as cell cycle progression, transcriptional regulation, and hormone signaling. Polyubiquitination is a signal for the 26S proteasome to destroy earmarked proteins, but depending on the polyubiquitin chain topology, it can also result in new protein properties. Both ubiquitin-orchestrated protein degradation and modification have also been shown to be essential for the host's immune response to pathogens. Many animal and plant pathogenic bacteria utilize type III and/or type IV secretion systems to inject effector proteins into host cells, where they subvert host signaling cascades as part of their infection strategy. Recent progress in the determination of effector function has taught us that playing with the host's ubiquitination system seems a general tactic among bacteria. Here, we discuss how bacteria exploit this system to control the timing of their effectors' action by programming them for degradation, to block specific intermediates in mammalian or plant innate immunity, or to target host proteins for degradation by mimicking specific ubiquitin/proteasome system components. In addition to analyzing the effectors that have been described in the literature, we screened publicly available bacterial genomes for mimicry of ubiquitin proteasome system subunits and detected several new putative effectors. Our understanding of the intimate interplay between pathogens and their host's ubiquitin proteasome system is just beginning. This exciting research field will aid in better understanding this interplay, and may also provide new insights into eukaryotic ubiquitination processes.
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Affiliation(s)
| | | | | | - Nemo Peeters
- * To whom correspondence should be addressed. E-mail:
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22
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Mittal R, Peak-Chew SY, McMahon HT. Acetylation of MEK2 and I kappa B kinase (IKK) activation loop residues by YopJ inhibits signaling. Proc Natl Acad Sci U S A 2006; 103:18574-9. [PMID: 17116858 PMCID: PMC1654131 DOI: 10.1073/pnas.0608995103] [Citation(s) in RCA: 229] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
To overcome host defenses, bacterial pathogens of the genus Yersinia inject specific effector proteins into colonized mammalian cells. One such virulence factor, YopJ, inhibits the host inflammatory response and induces apoptosis of immune cells by blocking multiple signaling pathways, including the MAPK and NF-kappaB pathways. In this study, we show that YopJ exerts its deleterious effects by catalyzing the acetylation of two serine residues in the activation loop of the MAP kinase kinase, MEK2. This covalent modification prevents the phosphorylation of these serine residues that is required for activation of MEK2 and downstream signal propagation. We also show that YopJ causes acetylation of a threonine residue in the activation loop of both the alpha and beta subunits of the NF-kappaB pathway kinase, IKK. These results establish a hitherto uncharacterized mode of action for bacterial toxins and suggest the possibility that serine/threonine acetylation may occur even under nonpathogenic conditions and may be a widespread protein modification regulating protein function in eukaryotic cells.
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Affiliation(s)
- Rohit Mittal
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
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23
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Grillari J, Katinger H, Voglauer R. Aging and the ubiquitinome: traditional and non-traditional functions of ubiquitin in aging cells and tissues. Exp Gerontol 2006; 41:1067-79. [PMID: 17052881 DOI: 10.1016/j.exger.2006.07.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 07/13/2006] [Accepted: 07/18/2006] [Indexed: 01/01/2023]
Abstract
Ubiquitination of endogenous proteins is one of the key regulatory steps of protein degradation followed by regulation of proteasome activity. During the last years evidence has increased that proteasome activity is decreased during the aging process in various model systems and that these changes might be causally related to aging and aging associated diseases. Since in most instances ubiquitination is the primary event in target selection, the system of ubiquitination and deubiquitination might be of similar importance. Furthermore, ubiquitination and proteasomal degradation are not completely congruent, since ubiquitination also confers functions different from giving "the kiss of death" to proteins. Depending on mono- and polyubiquitination and on how ubiquitin chains are linked together, ubiquitination is involved in transcriptional regulation, receptor internalization, DNA repair, and stabilization of protein complexes. This review is therefore the first to summarize the current knowledge regarding the ubiquitinome and the underlying ubiquitin ligases and deubiquitinating enzymes in replicative senescence, tissue aging as well as in segmental progeroid syndromes and to discuss potential causes and consequences for aging.
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Affiliation(s)
- Johannes Grillari
- Department of Biotechnology, Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Vienna Muthgasse 18, A-1190 Vienna, Austria.
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24
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Abstract
Pathogenic Yersinia spp. secrete the effector YopJ (YopP) into host cells to counteract cytokine production and to induce programmed cell death (apoptosis). YopJ achieves these aims by inactivating mitogen-activated protein kinase (MAPK) and nuclear factor kappaB signaling pathways. YopJ was shown to bind to members of the MAPK kinase (MKK) family and was predicted to have protease activity toward ubiquitin (Ub)-like proteins. In a recent report, YopJ was demonstrated to inactivate MKKs via acetylation of critical serine or threonine residues. The ramifications of these exciting results are discussed in the context of other studies implicating YopJ as a Ub-like protease.
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Affiliation(s)
- James B Bliska
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, SUNY Stony Brook, Stony Brook, New York 11794-5222, USA.
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25
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Thiefes A, Wolf A, Doerrie A, A Grassl G, Matsumoto K, Autenrieth I, Bohn E, Sakurai H, Niedenthal R, Resch K, Kracht M. The Yersinia enterocolitica effector YopP inhibits host cell signalling by inactivating the protein kinase TAK1 in the IL-1 signalling pathway. EMBO Rep 2006; 7:838-44. [PMID: 16845370 PMCID: PMC1525148 DOI: 10.1038/sj.embor.7400754] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 06/07/2006] [Accepted: 06/12/2006] [Indexed: 11/09/2022] Open
Abstract
The mechanism by which YopP simultaneously inhibits mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB pathways has been elusive. Ectopic expression of YopP inhibits the activity and ubiquitination of a complex consisting of overexpressed TGF-beta-activated kinase 1 (TAK1) and its subunit TAK1-binding protein (TAB)1, but not of MEK kinase 1. YopP, but not the catalytically inactive mutant YopP(C172A), also suppresses basal and interleukin-1-inducible activation of endogenous TAK1, TAB1 and TAB2. YopP does not affect the interaction of TAK1, TAB1 and TAB2 but inhibits autophosphorylation of TAK1 at Thr 187 and phosphorylation of TAB1 at Ser 438. Glutathione S-transferase-tagged YopP (GST-YopP) binds to MAPK kinase (MAPKK)4 and TAB1 but not to TAK1 or TAB2 in vitro. Furthermore, YopP in synergy with a previously described negative regulatory feedback loop inhibits TAK1 by MAPKK6-p38-mediated TAB1 phosphorylation. Taken together, these data strongly suggest that YopP binds to TAB1 and directly inhibits TAK1 activity by affecting constitutive TAK1 and TAB1 ubiquitination that is required for autoactivation of TAK1.
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Affiliation(s)
- Axel Thiefes
- Institute of Pharmacology, Medical School Hannover, 30625 Hannover, Germany
| | - Alexander Wolf
- Institute of Pharmacology, Medical School Hannover, 30625 Hannover, Germany
| | - Anneke Doerrie
- Institute of Pharmacology, Medical School Hannover, 30625 Hannover, Germany
| | - Guntram A Grassl
- Institute of Medical Microbiology and Hygiene, Eberhard-Karls University, 72076 Tübingen, Germany
| | - Kunihiro Matsumoto
- Department of Molecular Biology, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Ingo Autenrieth
- Institute of Medical Microbiology and Hygiene, Eberhard-Karls University, 72076 Tübingen, Germany
| | - Erwin Bohn
- Institute of Medical Microbiology and Hygiene, Eberhard-Karls University, 72076 Tübingen, Germany
| | - Hiroaki Sakurai
- Division of Pathogenic Biochemistry, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Rainer Niedenthal
- Institute of Biochemistry, Medical School Hannover, 30625 Hannover, Germany
| | - Klaus Resch
- Institute of Pharmacology, Medical School Hannover, 30625 Hannover, Germany
| | - Michael Kracht
- Institute of Pharmacology, Medical School Hannover, 30625 Hannover, Germany
- Tel: +49 511 532 2800/2802; Fax: +49 511 532 4081; E-mail:
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26
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Nasr R, Chiari E, El-Sabban M, Mahieux R, Kfoury Y, Abdulhay M, Yazbeck V, Hermine O, de Thé H, Pique C, Bazarbachi A. Tax ubiquitylation and sumoylation control critical cytoplasmic and nuclear steps of NF-κB activation. Blood 2006; 107:4021-9. [PMID: 16424386 DOI: 10.1182/blood-2005-09-3572] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Tax oncoprotein plays a crucial role in the proliferation and transformation of human T-cell leukemia virus type I (HTLV-I)–infected T lymphocytes through various mechanisms, including activation of the nuclear factor (NF)–κB pathway. We found that cytoplasmic ubiquitylation of Tax C-terminal lysines is critical for Tax binding to the IkappaB kinase complex and subsequent nuclear translocation of RelA. Conversely, we demonstrate that the same lysines are sumoylated in the nucleus, an event required for the formation of RelA/p300-enriched Tax nuclear bodies and full NF-κB transcriptional activation. In contrast, Tax ubiquitylation and sumoylation are dispensable for its activation of cyclic adenosine monophosphate response element binding protein (CREB)–dependent genes. Thus, ubiquitylation and sumoylation of the same residues of Tax regulate 2 essential steps controlling NF-κB activation, demonstrating how these posttranslational modifications can cooperate to promote Tax-induced transformation.
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Affiliation(s)
- Rihab Nasr
- Department of Internal Medicine, American University of Beirut, PO Box 113-6044, Beirut, Lebanon
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27
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Haase R, Richter K, Pfaffinger G, Courtois G, Ruckdeschel K. Yersinia outer protein P suppresses TGF-beta-activated kinase-1 activity to impair innate immune signaling in Yersinia enterocolitica-infected cells. THE JOURNAL OF IMMUNOLOGY 2006; 175:8209-17. [PMID: 16339560 DOI: 10.4049/jimmunol.175.12.8209] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Pathogenic Yersinia spp. use a panel of virulence proteins that antagonize signal transduction processes in infected cells to undermine host defense mechanisms. One of these proteins, Yersinia enterocolitica outer protein P (YopP), down-regulates the NF-kappaB and MAPK signaling pathways, which suppresses the proinflammatory host immune response. In this study, we explored the mechanism by which YopP succeeds to simultaneously disrupt several of these key signaling pathways of innate immunity. Our data show that YopP operates upstream of its characterized eukaryotic binding partner IkappaB kinase-beta to shut down the NF-kappaB signaling cascade. Accordingly, YopP efficiently impaired the activities of TGF-beta-activated kinase-1 (TAK1) in infected cells. TAK1 is an important activator of the IkappaB kinase complex in the TLR signaling cascade. The repression of TAK1 activities correlated with reduced activation of NF-kappaB- as well as AP-1-dependent reporter gene expression in Yersinia-infected murine macrophages. This suggests that the impairment of the TAK1 enzymatic activities by Yersinia critically contributes to down-regulate activation of NF-kappaB and of MAPK members in infected host cells. The inhibition of TAK1 potentially results from the blockade of signaling events that control TAK1 induction. This process could involve the attenuation of ubiquitination of the upstream signal transmitter TNFR-associated factor-6. Together, these results indicate that, by silencing the TAK1 signaling complex, Yersinia counteracts the induction of several conserved signaling pathways of innate immunity, which aids the bacterium in subverting the host immune response.
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Affiliation(s)
- Rudolf Haase
- Max von Pettenkofer-Institute for Hygiene and Medical Microbiology, Munich, Germany
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28
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Abstract
Bacterial invasion of eukaryotic cells and host recognition and killing of the invading bacteria are a key issue in determining the fate of bacterial infection. Once inside host cells, pathogenic bacteria often modify the phagosomal compartment or enter the host cytosol to escape from the lytic compartment and gain a replicative niche. Cytosolic invaders, however, are monitored by host innate immune systems, such as mediated by Nod/CARD family proteins, which induce inflammatory responses via activation of NF-kappaB. Furthermore, recent studies indicate that autophagy, a major cytoplasmic degradation system that eliminates cytosolic protein and organelles, also recognizes invading bacteria. Indeed, unless they are able to circumvent entrapping by autophagic membranes, bacteria targeted by autophagy ultimately undergo degradation by delivery into autolysosomes. In this article, we review recent advances in understanding of Shigella strategies to infect epithelial cells, and then focus on recent studies of an intriguing bacterial survival strategy against autophagic degradation.
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Affiliation(s)
- Michinaga Ogawa
- Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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29
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Bernier M, Kwon YK, Pandey SK, Zhu TN, Zhao RJ, Maciuk A, He HJ, Decabo R, Kole S. Binding of Manumycin A Inhibits IκB Kinase β Activity. J Biol Chem 2006; 281:2551-61. [PMID: 16319058 DOI: 10.1074/jbc.m511878200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
IkappaB kinase (IKK) catalytic subunits play a key role in cytokinemediated nuclear factor (NF)-kappaB signaling, and a loss of NF-kappaB function appears to inhibit inflammation and oncogenesis. Manumycin A is a potent and selective farnesyltransferase inhibitor with antitumor activity. We found that manumycin A caused a rapid and potent inhibition of IKK activity induced by tumor necrosis factor alpha in a number of cell types. Most unexpectedly, other classes of farnesyltransferase inhibitors had no inhibitory effect. To identify the molecular mechanisms of manumycin A action, cultured human HepG2 hepatoma cells were transiently transfected with various IKKalpha and IKKbeta constructs, and a striking difference in manumycin A sensitivity was observed. Furthermore, cells expressing wild-type IKKbeta and IKKbeta mutated in the activation loop at Cys-179 exhibited covalent homotypic dimerization of IKKbeta in response to manumycin A, whereas substitution of Cys-662 and -716 conferred protection against dimer formation. Direct inhibition of IKK activity and formation of stable IKKbeta dimers were observed in the presence of manumycin A that could be blocked by dithiothreitol. IKK interaction with the adaptor protein IKKgamma/NEMO was disrupted in manumycin A-treated cells. Most importantly, administration of manumycin A to mice xenografted with murine B16F10 tumors caused potent IKK-suppressive effects. Thus, manumycin A with its epoxyquinoid moieties plays an important regulatory function in IKK signaling through pathways distinct from its role as a protein farnesylation inhibitor.
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Affiliation(s)
- Michel Bernier
- Diabetes Section, Bioanalytical Chemistry and Drug Discovery Section, Laboratory of Clinical Investigation, and Laboratory of Experimental Gerontology, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA.
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30
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Viboud GI, Bliska JB. Yersinia outer proteins: role in modulation of host cell signaling responses and pathogenesis. Annu Rev Microbiol 2006; 59:69-89. [PMID: 15847602 DOI: 10.1146/annurev.micro.59.030804.121320] [Citation(s) in RCA: 447] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A type III secretion system (TTSS) is encoded on a virulence plasmid that is common to three pathogenic Yersinia species: Y. enterocolitica, Y. pseudotuberculosis, and Y. pestis. Pathogenic Yersinia species require this TTSS to survive and replicate within lymphoid tissues of their animal or human hosts. A set of pathogenicity factors, including those known as Yersinia outer proteins (Yops), is exported by this system upon bacterial infection of host cells. Two translocator Yops (YopB and YopD) insert into the host plasma membrane and function to transport six effector Yops (YopO, YopH, YopM, YopT, YopJ, and YopE) into the cytosol of the host cell. Effector Yops function to counteract multiple signaling responses in the infected host cell. The signaling responses counteracted by Yops are initiated by phagocytic receptors, Toll-like receptors, translocator Yops, and additional mechanisms. Innate and adaptive immune responses are thwarted as a consequence of Yop activities. A biochemical function for each effector Yop has been established, and the importance of these proteins for the pathogenesis process is being elucidated. This review focuses on the biochemical functions of Yops, the signaling pathways they modulate, and the role of these proteins in Yersinia virulence.
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Affiliation(s)
- Gloria I Viboud
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, SUNY Stony Brook, Stony Brook, New York 11794-5222, USA.
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31
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Carter RS, Pennington KN, Arrate P, Oltz EM, Ballard DW. Site-specific Monoubiquitination of IκB Kinase IKKβ Regulates Its Phosphorylation and Persistent Activation. J Biol Chem 2005; 280:43272-9. [PMID: 16267042 DOI: 10.1074/jbc.m508656200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Transcription factor NF-kappaB governs the expression of multiple genes involved in cell growth, immunity, and inflammation. Nuclear translocation of NF-kappaB is regulated from the cytoplasm by IkappaB kinase-beta (IKKbeta), which earmarks inhibitors of NF-kappaB for polyubiquination and proteasome-mediated degradation. Activation of IKKbeta is contingent upon signal-induced phosphorylation of its T loop at Ser-177/Ser-181. T loop phosphorylation also renders IKKbeta a substrate for monoubiquitination in cells exposed to chronic activating cues, such as the Tax oncoprotein or sustained signaling through proinflammatory cytokine receptors. Here we provide evidence that the T loop-proximal residue Lys-163 in IKKbeta serves as a major site for signal-induced monoubiquitination with significant regulatory potential. Conservative replacement of Lys-163 with Arg yielded a monoubiquitination-defective mutant of IKKbeta that retains kinase activity in Tax-expressing cells but is impaired for activation mediated by chronic signaling from the type 1 receptor for tumor necrosis factor-alpha. Phosphopeptide mapping experiments revealed that the Lys-163 --> Arg mutation also interferes with proper in vivo but not in vitro phosphorylation of cytokine-responsive serine residues located in the distal C-terminal region of IKKbeta. Taken together, these data indicate that chronic phosphorylation of IKKbeta at Ser-177/Ser-181 leads to monoubiquitin attachment at nearby Lys-163, which in turn modulates the phosphorylation status of IKKbeta at select C-terminal serines. This mechanism for post-translational cross-talk may play an important role in the control of IKKbeta signaling during chronic inflammation.
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Affiliation(s)
- Robert S Carter
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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32
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Song YS, Lee YS, Chan PH. Oxidative stress transiently decreases the IKK complex (IKKalpha, beta, and gamma), an upstream component of NF-kappaB signaling, after transient focal cerebral ischemia in mice. J Cereb Blood Flow Metab 2005; 25:1301-11. [PMID: 15829915 DOI: 10.1038/sj.jcbfm.9600123] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nuclear factor-kappaB (NF-kappaB) has a central role in coordinating the expression of a wide variety of genes that control cerebral ischemia. Although there has been intense research on NF-kappaB, its mechanisms in the ischemic brain have not been clearly elucidated. We investigated the temporal profile of NF-kappaB-related genes using a complementary DNA array method in wild-type mice and human copper/zinc-superoxide dismutase transgenic (SOD 1 Tg) mice that had low-level reactive oxygen species (ROS) by scavenging superoxide. Our DNA array showed that IkappaB kinase (IKK) complex (IKKalpha, beta, and gamma) mRNA in the wild-type mice was decreased as early as 1 h after reperfusion, after 30 mins of transient focal cerebral ischemia (tFCI). In contrast, tFCI in the SOD1 Tg mice caused an increase in the IKK complex. The IKK complex protein levels were also drastically decreased at 1 h in the wild-type mice, but did not change in the SOD 1 Tg mice throughout the 7 days. Electrophoretic mobility shift assay revealed activation of NF-kappaB DNA binding after tFCI in the wild-type mice. Nuclear factor-kappaB activation occurred at the same time, as did the phosphorylation and degradation of the inhibitory protein IkappaBalpha. However, SOD 1 prevented NF-kappaB activation, and phosphorylation and degradation of IkappaBalpha after tFCI. Superoxide production and ubiquitinated protein in the SOD 1 Tg mice were also lower than in the wild-type mice after tFCI. These results suggest that ROS are implicated in transient downregulation of IKKalpha, beta, and gamma in cerebral ischemia.
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Affiliation(s)
- Yun S Song
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA
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Abstract
Ubiquitylation is an emerging mechanism implicated in a variety of nonproteolytic cellular functions. The attachment of a single ubiquitin (Ub) or poly-Ub (lysine 63) chains to proteins control gene transcription, DNA repair and replication, intracellular trafficking and virus budding. In these processes, protein ubiquitylation exhibits inducibility, reversibility and recognition by specialized domains, features similar to protein phosphorylation, which enable Ub to act as a signaling device. Here, we highlight several recent examples on how Ub regulates signaling and how signaling regulates ubiquitylation during physiological and pathological cellular processes.
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Affiliation(s)
- Kaisa Haglund
- Institute for Biochemistry II, University Hospital of Goethe University, Frankfurt am Main, Germany
| | - Ivan Dikic
- Institute for Biochemistry II, University Hospital of Goethe University, Frankfurt am Main, Germany
- Mediterranean Institute for Life Sciences (MedILS), Split, Croatia
- Institute for Biochemistry II, University Hospital of Goethe University, Theodor-Stern-Kai 7, Frankfurt am Main, 60590, Germany. Tel: +49 69 6301 83647; Fax: +49 69 6301 5577; E-mail:
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Kray AE, Carter RS, Pennington KN, Gomez RJ, Sanders LE, Llanes JM, Khan WN, Ballard DW, Wadzinski BE. Positive regulation of IkappaB kinase signaling by protein serine/threonine phosphatase 2A. J Biol Chem 2005; 280:35974-82. [PMID: 16126728 DOI: 10.1074/jbc.m506093200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription factor NF-kappaB plays a key regulatory role in the cellular response to pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF). In the absence of TNF, NF-kappaB is sequestered in the cytoplasm by inhibitory IkappaB proteins. Phosphorylation of IkappaBby the beta-catalytic subunit of IKK, a multicomponent IkappaB kinase, targets the inhibitor for proteolytic destruction and facilitates nuclear translocation of NF-kappaB. This pathway is initiated by TNF-dependent phosphorylation of T loop serines in IKKbeta, which greatly stimulates IkappaB kinase activity. Prior in vitro mixing experiments indicate that protein serine/threonine phosphatase 2A (PP2A) can dephosphorylate these T loop serines and inactivate IKK, suggesting a negative regulatory role for PP2A in IKK signaling. Here we provided several in vivo lines of evidence indicating that PP2A plays a positive rather than a negative role in the regulation of IKK. First, TNF-induced degradation of IkappaB is attenuated in cells treated with okadaic acid or fostriecin, two potent inhibitors of PP2A. Second, PP2A forms stable complexes with IKK in untransfected mammalian cells. This interaction is critically dependent on amino acid residues 121-179 of the IKKgamma regulatory subunit. Third, deletion of the PP2A-binding site in IKKgamma attenuates T loop phosphorylation and catalytic activation of IKKbeta in cells treated with TNF. Taken together, these data provide strong evidence that the formation of IKK.PP2A complexes is required for the proper induction of IkappaB kinase activity in vivo.
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Affiliation(s)
- Arlene E Kray
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600, USA
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Navarro L, Alto NM, Dixon JE. Functions of the Yersinia effector proteins in inhibiting host immune responses. Curr Opin Microbiol 2005; 8:21-7. [PMID: 15694853 DOI: 10.1016/j.mib.2004.12.014] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The invasion strategies used by Yersinia species involve the 'hijacking' of host cellular signaling pathways, often involving microbial gene products that mimic the functions of the cellular proteins. Yersinia uses a type III secretion system to inject these microbial gene products, referred to as Yersinia effector proteins, into the host cytosol. Yersinia effector proteins can inhibit the host immune system through a diverse array of mechanisms including inhibition of the inflammatory response by interfering with cytokine production, inhibition of phagocytosis by disrupting the actin cytoskeleton, induction of apoptosis in macrophages and through the formation of novel signaling complexes.
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Affiliation(s)
- Lorena Navarro
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093-0721, USA
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Haefner B. The transcription factor NF-kappaB as drug target. PROGRESS IN MEDICINAL CHEMISTRY 2005; 43:137-88. [PMID: 15850825 DOI: 10.1016/s0079-6468(05)43005-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Affiliation(s)
- Burkhard Haefner
- Department of Inflammation, Johnson & Johnson Pharmaceutical Research and Development, A Division of Janssen Pharmaceutica, Beerse, Belgium
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Monitor – Biology. Drug Discov Today 2004. [DOI: 10.1016/s1359-6446(03)02992-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Abstract
Ubiquitination is a post-translational modification in which a small conserved peptide, ubiquitin, is appended to target proteins in the cell, through a series of complex enzymatic reactions. Recently, a particular form of ubiquitination, monoubiquitination, has emerged as a nonproteolytic reversible modification that controls protein function. In this review, we highlight recent findings on monoubiquitination as a signaling-induced modification, controlled, among others, by pathways originating from active receptor tyrosine kinases. Furthermore, we review the major cellular processes controlled by ubiquitin modification, including membrane trafficking, histone function, transcription regulation, DNA repair, and DNA replication.
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Affiliation(s)
- S Sigismund
- IFOM, The FIRC Institute for Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
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