1
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Barczewski AH, Ragusa MJ, Mierke DF, Pellegrini M. Production, Crystallization, and Structure Determination of the IKK-binding Domain of NEMO. J Vis Exp 2019. [PMID: 31929506 DOI: 10.3791/60339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
NEMO is a scaffolding protein which plays an essential role in the NF-κB pathway by assembling the IKK-complex with the kinases IKKα and IKKβ. Upon activation, the IKK complex phosphorylates the IκB molecules leading to NF-κB nuclear translocation and activation of target genes. Inhibition of the NEMO/IKK interaction is an attractive therapeutic paradigm for the modulation of NF-κB pathway activity, making NEMO a target for inhibitors design and discovery. To facilitate the process of discovery and optimization of NEMO inhibitors, we engineered an improved construct of the IKK-binding domain of NEMO that would allow for structure determination of the protein in the apo form and while bound to small molecular weight inhibitors. Here, we present the strategy utilized for the design, expression and structural characterization of the IKK-binding domain of NEMO. The protein is expressed in E. coli cells, solubilized under denaturing conditions and purified through three chromatographic steps. We discuss the protocols for obtaining crystals for structure determination and describe data acquisition and analysis strategies. The protocols will find wide applicability to the structure determination of complexes of NEMO and small molecule inhibitors.
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2
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The IKK-binding domain of NEMO is an irregular coiled coil with a dynamic binding interface. Sci Rep 2019; 9:2950. [PMID: 30814588 PMCID: PMC6393490 DOI: 10.1038/s41598-019-39588-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 01/25/2019] [Indexed: 11/29/2022] Open
Abstract
NEMO is an essential component in the activation of the canonical NF-κB pathway and exerts its function by recruiting the IκB kinases (IKK) to the IKK complex. Inhibition of the NEMO/IKKs interaction is an attractive therapeutic paradigm for diseases related to NF-κB mis-regulation, but a difficult endeavor because of the extensive protein-protein interface. Here we report the high-resolution structure of the unbound IKKβ-binding domain of NEMO that will greatly facilitate the design of NEMO/IKK inhibitors. The structures of unbound NEMO show a closed conformation that partially occludes the three binding hot-spots and suggest a facile transition to an open state that can accommodate ligand binding. By fusing coiled-coil adaptors to the IKKβ-binding domain of NEMO, we succeeded in creating a protein with improved solution behavior, IKKβ-binding affinity and crystallization compatibility, which will enable the structural characterization of new NEMO/inhibitor complexes.
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3
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Eguchi R, Karim MB, Hu P, Sato T, Ono N, Kanaya S, Altaf-Ul-Amin M. An integrative network-based approach to identify novel disease genes and pathways: a case study in the context of inflammatory bowel disease. BMC Bioinformatics 2018; 19:264. [PMID: 30005591 PMCID: PMC6043997 DOI: 10.1186/s12859-018-2251-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 06/18/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND There are different and complicated associations between genes and diseases. Finding the causal associations between genes and specific diseases is still challenging. In this work we present a method to predict novel associations of genes and pathways with inflammatory bowel disease (IBD) by integrating information of differential gene expression, protein-protein interaction and known disease genes related to IBD. RESULTS We downloaded IBD gene expression data from NCBI's Gene Expression Omnibus, performed statistical analysis to determine differentially expressed genes, collected known IBD genes from DisGeNet database, which were used to construct a IBD related PPI network with HIPPIE database. We adapted our graph-based clustering algorithm DPClusO to cluster the disease PPI network. We evaluated the statistical significance of the identified clusters in the context of determining the richness of IBD genes using Fisher's exact test and predicted novel genes related to IBD. We showed 93.8% of our predictions are correct in the context of other databases and published literatures related to IBD. CONCLUSIONS Finding disease-causing genes is necessary for developing drugs with synergistic effect targeting many genes simultaneously. Here we present an approach to identify novel disease genes and pathways and discuss our approach in the context of IBD. The approach can be generalized to find disease-associated genes for other diseases.
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Affiliation(s)
- Ryohei Eguchi
- Graduate School of Science and Technology & NAIST Data Science Center, Nara Institute of Science and Technology, Nara, Japan
| | - Mohammand Bozlul Karim
- Graduate School of Science and Technology & NAIST Data Science Center, Nara Institute of Science and Technology, Nara, Japan
| | - Pingzhao Hu
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Canada.,George and Fay Yee Centre for Healthcare Innovation, University of Manitoba, Winnipeg, Canada.,Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, Canada
| | - Tetsuo Sato
- Graduate School of Science and Technology & NAIST Data Science Center, Nara Institute of Science and Technology, Nara, Japan.,Department of Radiological Technology, Gunma Prefectural College of Health Sciences, Gunma, Japan
| | - Naoaki Ono
- Graduate School of Science and Technology & NAIST Data Science Center, Nara Institute of Science and Technology, Nara, Japan
| | - Shigehiko Kanaya
- Graduate School of Science and Technology & NAIST Data Science Center, Nara Institute of Science and Technology, Nara, Japan
| | - Md Altaf-Ul-Amin
- Graduate School of Science and Technology & NAIST Data Science Center, Nara Institute of Science and Technology, Nara, Japan.
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4
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Alshenqiti A, Nashabat M, AlGhoraibi H, Tamimi O, Alfadhel M. Pulmonary hypertension and vasculopathy in incontinentia pigmenti: a case report. Ther Clin Risk Manag 2017; 13:629-634. [PMID: 28533687 PMCID: PMC5431708 DOI: 10.2147/tcrm.s134705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Incontinentia pigmenti (IP; Bloch-Sulzberger syndrome) is a rare, genetic syndrome inherited as an X-linked dominant trait. It primarily affects female infants and is lethal in the majority of males during fetal life. The clinical findings include skin lesions, developmental defects, and defects of the eyes, teeth, skeletal system, and central nervous system. Cardiovascular complications of this disease in general, and pulmonary hypertension in particular, are extremely rare. This report describes the case of a 3-year-old girl with IP complicated by pulmonary arterial hypertension. Extensive cardiology workup done to the patient indicates underlying vasculopathy. This report sheds light on the relationship between IP and pulmonary hypertension, reviews the previously reported cases, and compares them with the reported case.
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Affiliation(s)
- Abduljabbar Alshenqiti
- Division of Genetics, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz Uiversity for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Marwan Nashabat
- Division of Genetics, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz Uiversity for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Hissah AlGhoraibi
- Division of Genetics, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz Uiversity for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Omar Tamimi
- Department of Cardiology, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Majid Alfadhel
- Division of Genetics, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz Uiversity for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (NGHA), Riyadh, Saudi Arabia
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5
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Medunjanin S, Schleithoff L, Fiegehenn C, Weinert S, Zuschratter W, Braun-Dullaeus RC. GSK-3β controls NF-kappaB activity via IKKγ/NEMO. Sci Rep 2016; 6:38553. [PMID: 27929056 PMCID: PMC5144080 DOI: 10.1038/srep38553] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/09/2016] [Indexed: 12/24/2022] Open
Abstract
The NF-κB signaling pathway is central for the innate immune response and its deregulation is found in multiple disorders such as autoimmune, chronic inflammatory and metabolic diseases. IKKγ/NEMO is essential for NF-κB activation and NEMO dysfunction in humans has been linked to so-called progeria syndromes, which are characterized by advanced ageing due to age-dependent inflammatory diseases. It has been suggested that glycogen synthase kinase-3β (GSK-3β) participates in NF-κB regulation but the exact mechanism remained incompletely understood. In this study, we identified NEMO as a GSK-3β substrate that is phosphorylated at serine 8, 17, 31 and 43 located within its N-terminal domain. The kinase forms a complex with wild-type NEMO while point mutations of NEMO at the specific serines abrogated GSK-3β binding and subsequent phosphorylation of NEMO resulting in its destabilization. However, K63-linked polyubiquitination was augmented in mutated NEMO explaining an increased binding to IKKα and IKKβ. Even IκBα was found degraded. Still, TNFα-stimulated NF-κB activation was impaired pointing towards an un-controlled signalling process. Our data suggest that GSK-3β is critically important for ordered NF-κB signalling through modulation of NEMO phosphorylation.
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Affiliation(s)
- Senad Medunjanin
- Internal Medicine/Cardiology and Angiology, Magdeburg University, Magdeburg, Germany
| | - Lisa Schleithoff
- Internal Medicine/Cardiology and Angiology, Magdeburg University, Magdeburg, Germany
| | - Christian Fiegehenn
- Internal Medicine/Cardiology and Angiology, Magdeburg University, Magdeburg, Germany
| | - Soenke Weinert
- Internal Medicine/Cardiology and Angiology, Magdeburg University, Magdeburg, Germany
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6
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Guo B, Audu CO, Cochran JC, Mierke DF, Pellegrini M. Protein engineering of the N-terminus of NEMO: structure stabilization and rescue of IKKβ binding. Biochemistry 2014; 53:6776-85. [PMID: 25286246 PMCID: PMC4222529 DOI: 10.1021/bi500861x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
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NEMO is a scaffolding protein that,
together with the catalytic
subunits IKKα and IKKβ, plays an essential role in the
formation of the IKK complex and in the activation of the canonical
NF-κB pathway. Rational drug design targeting the IKK-binding
site on NEMO would benefit from structural insight, but to date, the
determination of the structure of unliganded NEMO has been hindered
by protein size and conformational heterogeneity. Here we show how
the utilization of a homodimeric coiled-coil adaptor sequence stabilizes
the minimal IKK-binding domain NEMO(44–111) and furthers our
understanding of the structural requirements for IKK binding. The
engineered constructs incorporating the coiled coil at the N-terminus,
C-terminus, or both ends of NEMO(44–111) present high thermal
stability and cooperative melting and, most importantly, restore IKKβ
binding affinity. We examined the consequences of structural content
and stability by circular dichoism and nuclear magnetic resonance
(NMR) and measured the binding affinity of each construct for IKKβ(701–745)
in a fluorescence anisotropy binding assay, allowing us to correlate
structural characteristics and stability to binding affinity. Our
results provide a method for engineering short stable NEMO constructs
to be suitable for structural characterization by NMR or X-ray crystallography.
Meanwhile, the rescuing of the binding affinity implies that a preordered
IKK-binding region of NEMO is compatible with IKK binding, and the
conformational heterogeneity observed in NEMO(44–111) may be
an artifact of the truncation.
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Affiliation(s)
- Bingqian Guo
- Department of Chemistry, Dartmouth College , Hanover, New Hampshire 03755, United States
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7
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Poziomczyk CS, Recuero JK, Bringhenti L, Maria FDS, Campos CW, Travi GM, Freitas AM, Maahs MAP, Zen PRG, Fiegenbaum M, Almeida STD, Bonamigo RR, Bau AEK. Incontinentia pigmenti. An Bras Dermatol 2014; 89:26-36. [PMID: 24626645 PMCID: PMC3938351 DOI: 10.1590/abd1806-4841.20142584] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 04/09/2013] [Indexed: 12/25/2022] Open
Abstract
Incontinentia pigmenti is a rare genodermatosis in which the skin involvement occurs
in all patients. Additionally, other ectodermal tissues may be affected, such as the
central nervous system, eyes, hair, nails and teeth. The disease has a X-linked
dominant inheritance pattern and is usually lethal to male fetuses. The
dermatological findings occur in four successive phases, following the lines of
Blaschko: First phase - vesicles on an erythematous base; second phase - verrucous
hyperkeratotic lesions; third phase - hyperchromic spots and fourth phase -
hypochromic atrophic lesions.
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Affiliation(s)
- Cláudia Schermann Poziomczyk
- Porto Alegre Health Sciences Federal University, Pathology Post-graduation Program, Porto AlegreRS, Brazil, MD, Dermatologist - MSc (in course) at the Pathology Post-graduation Program at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Júlia Kanaan Recuero
- Porto Alegre Health Sciences Federal University, Porto AlegreRS, Brazil, Medical Student at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Luana Bringhenti
- Porto Alegre Health Sciences Federal University, Porto AlegreRS, Brazil, Medical Student at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Fernanda Diffini Santa Maria
- Porto Alegre Health Sciences Federal University, Pathology Post-graduation Program, Porto AlegreRS, Brazil, DDS - MSc (in course) at the Pathology Post-graduation Program at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Carolina Wiltgen Campos
- Santa Casa de Misericórdia de Porto Alegre, Ophthalmology Program, Porto AlegreRS, Brazil, MD - Resident in the Ophthalmology Program at Santa Casa de Misericórdia de Porto Alegre - Porto Alegre (RS), Brazil
| | - Giovanni Marcos Travi
- Santa Casa de Misericórdia de Porto Alegre, Porto AlegreRS, Brazil, MD - Ophthalmologist with specialization in Pediatric Ophthalmology and Strabismus Licensed physician at Santa Casa de Misericórdia de Porto Alegre- Porto Alegre (RS), Brazil
| | - André Moraes Freitas
- Santa Casa de Misericórdia de Porto Alegre Ophthalmology Service, Ophthalmology Service, Retina Sector, Porto AlegreRS, Brazil, MD - Ophthalmologist - Chief of the Retina Sector at Santa Casa de Misericórdia de Porto Alegre Ophthalmology Service - Porto Alegre (RS), Brazil
| | - Marcia Angelica Peter Maahs
- Rio Grande do Sul Federal University, Porto AlegreRS, Brazil, DDS - Specialist in Orthodontics and Facial Orthopedics at Rio Grande do Sul Federal University (UFRGS). PhD in Dentistry at Rio Grande do Sul Pontifical Catholic University (PUCRS) - Substitute Professor of the Discipline of Orthodontics Applied to Speech Therapy at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Paulo Ricardo Gazzola Zen
- Porto Alegre Health Sciences Federal University, Pathology Post-graduation Program, Porto AlegreRS, Brazil, MD, PhD at the Pathology Post-graduation Program at Porto Alegre Health Sciences Federal University (UFCSPA) - Adjunct Professor of Genetics at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Marilu Fiegenbaum
- Porto Alegre Health Sciences Federal University, Basic Health Sciences Department, Porto AlegreRS, Brazil, Pharm. D. - PhD in Genetics and Molecular Biology at Rio Grande do Sul Federal University (UFRGS) - Adjunct Professor at the Basic Health Sciences Department at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Sheila Tamanini de Almeida
- Porto Alegre Health Sciences Federal University, Speech Therapy Department, Porto AlegreRS, Brazil, Speech-Language Pathologist (SLPs) - Specialist in Orofacial Motricity and Dysphagia. MSc in Health Sciences - Assistant Professor at the Speech Therapy Department at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Renan Rangel Bonamigo
- Porto Alegre Health Sciences Federal University, Pathology Postgraduation Program, Porto AlegreRS, Brazil, MD - PhD in Health Sciences at Rio Grande do Sul Federal University (UFRGS) - Head Professor of Dermatology and Professor of the Pathology Postgraduation Program at Porto Alegre Health Sciences Federal University (UFCSPA) - Porto Alegre (RS), Brazil
| | - Ana Elisa Kiszewski Bau
- Porto Alegre Health Sciences Federal University, Porto AlegreRS, Brazil, MD - PhD in Pathology at Porto Alegre Health Sciences Federal University (UFCSPA)- Adjunct Professor of Dermatology at Porto Alegre Health Sciences Federal University (UFCSPA). Pediatric Dermatologist at Santo Antonio Children's Hospital and at Santa Casa de Misericórdia de Porto Alegre - Porto Alegre (RS), Brazil
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8
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Abstract
Inhibitor of κB kinase (IKK) gamma (IKKγ), also known as nuclear factor κB (NF-κB) essential modulator (NEMO), is a component of the IKK complex that is essential for the activation of the NF-κB pathway. The NF-κB pathway plays a major role in the regulation of the expression of genes that are involved in immune response, inflammation, cell adhesion, cell survival and development. As part of the IKK complex, IKKγ plays a regulatory role by linking the complex to upstream signalling molecules. IKKγ contains two coiled-coil regions, a leucine zipper domain and a highly conserved zinc finger domain. Mutations affecting IKKγ have been associated with X-linked hypohidrotic ectodermal dysplasia with immune deficiency (HED-ID), with the majority of these mutations affecting the C-terminal region of the protein where the zinc finger is located. The zinc finger of IKKγ is needed for NF-κB activation in a cell- and stimulus-specific manner. The major mechanism by which the zinc finger plays this role appears to be the recognition of polyubiquitinated upstream signalling intermediates. This assertion reinforces the current notion that ubiquitination plays a major role in mediating protein–protein interactions in the NF-κB signalling pathway. Because the zinc finger domain of IKKγ is very likely involved in mediating interactions with ubiquitinated proteins, investigations that look for upstream activators or inhibitors of the IKK complex that bind to and interact with the zinc finger of IKKγ are required to gain a better insight into the exact roles of this domain and into the pathogenesis of HED-ID.
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Affiliation(s)
- Amde Selassie Shifera
- Department of Ophthalmology, University of California, San Francisco, CA 94143, USA.
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9
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Hai T, Yeung ML, Wood TG, Wei Y, Yamaoka S, Gatalica Z, Jeang KT, Brasier AR. An alternative splice product of IkappaB kinase (IKKgamma), IKKgamma-delta, differentially mediates cytokine and human T-cell leukemia virus type 1 tax-induced NF-kappaB activation. J Virol 2006; 80:4227-41. [PMID: 16611882 PMCID: PMC1472011 DOI: 10.1128/jvi.80.9.4227-4241.2006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 02/08/2006] [Indexed: 01/30/2023] Open
Abstract
NF-kappaB is an inducible transcription factor mediating innate immune responses whose activity is controlled by the multiprotein IkappaB kinase (IKK) "signalsome". The core IKK consists of two catalytic serine kinases, IKKalpha and IKKbeta, and a noncatalytic subunit, IKKgamma. IKKgamma is required for IKK activity by mediating kinase oligomerization and serving to couple the core catalytic subunits to upstream mitogen-activated protein 3-kinase cascades. We have discovered an alternatively spliced IKKgamma mRNA isoform, encoding an in-frame deletion of exon 5, termed IKKgamma-delta. Using a specific reverse transcription-PCR assay, we find that IKKgamma-delta is widely expressed in cultured human cells and normal human tissues. Because IKKgamma-Delta protein is lacking a critical coiled-coil domain important in protein-protein interactions, we sought to determine its signaling properties by examining its ability to self associate, couple to activators of the canonical pathway, and mediate human T-cell leukemia virus type 1 (HTLV-1) Tax-induced NF-kappaB activity. Coimmunoprecipitation and confocal colocalization assays indicate IKKgamma-delta has strong homo- and heterotypic association with wild-type (WT) IKKgamma and, like IKKgamma WT, associates with the IKKbeta kinase. Similarly, IKKgamma-delta mediates IKK kinase activity and downstream NF-kappaB-dependent transcription in response to tumor necrosis factor (TNF) and the NF-kappaB-inducing kinase-IKKalpha signaling pathway. Surprisingly, however, in contrast to IKKgamma WT, IKKgamma-delta is not able to mediate HTLV-1 Tax-induced NF-kappaB-dependent transcription, even though IKKgamma-delta binds and colocalizes with Tax. These observations suggest that IKKgamma-delta is a functionally distinct alternatively spliced mRNA product differentially mediating TNF-induced, but not Tax-induced, signals converging on the IKK signalsome. Differing levels of IKKgamma-delta expression, therefore, may affect signal transduction cascades coupling to IKK.
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Affiliation(s)
- Tao Hai
- Department of Internal Medicine, The University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1060, USA
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10
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Makris C, Roberts JL, Karin M. The carboxyl-terminal region of IkappaB kinase gamma (IKKgamma) is required for full IKK activation. Mol Cell Biol 2002; 22:6573-81. [PMID: 12192055 PMCID: PMC135629 DOI: 10.1128/mcb.22.18.6573-6581.2002] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
IkappaB kinase gamma (IKKgamma) (also known as NEMO, Fip-3, and IKKAP-1) is the essential regulatory component of the IKK complex; it is required for NF-kappaB activation by various stimuli, including tumor necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1), phorbol esters, lipopolysaccharides, and double-stranded RNA. IKKgamma is encoded by an X-linked gene, deficiencies in which may result in two human genetic disorders, incontinentia pigmenti (IP) and hypohidrotic ectodermal dysplasia with severe immunodeficiency. Subsequent to the linkage of IKKgamma deficiency to IP, we biochemically characterized the effects of a mutation occurring in an IP-affected family on IKK activity and NF-kappaB signaling. This particular mutation results in premature termination, such that the variant IKKgamma protein lacks its putative C-terminal Zn finger and, due to decreased mRNA stability, is underexpressed. Correspondingly, IKK and NF-kappaB activation by TNF-alpha and, to a lesser extent, IL-1 are reduced. Mutagenesis of the C-terminal region of IKKgamma was performed in an attempt to define the role of the putative Zn finger and other potential functional motifs in this region. The mutants were expressed in IKKgamma-deficient murine embryonic fibroblasts (MEFs) at levels comparable to those of endogenous IKKgamma in wild-type MEFs and were able to associate with IKKalpha and IKKbeta. Substitution of two leucines within a C-terminal leucine zipper motif markedly reduced IKK activation by TNF-alpha and IL-1. Another point mutation resulting in a cysteine-to-serine substitution within the putative Zn finger motif affected IKK activation by TNF-alpha but not by IL-1. These results may explain why cells that express these or similar mutant alleles are sensitive to TNF-alpha-induced apoptosis despite being able to activate NF-kappaB in response to other stimuli.
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Affiliation(s)
- Constantin Makris
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California, San Diego, La Jolla 92093-0636, USA
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11
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Abstract
Hyper-IgM (HIM) syndrome is a rare immunodeficiency characterized by low or absent IgG, IgA, and IgE with normal or elevated levels of IgM. This disorder can be acquired or familial with either X-linked or autosomal patterns of inheritance. The X-linked form of the disease is a consequence of mutations in the CD40 ligand (CD40L) gene that encodes a protein expressed primarily on activated CD4+ T cells. The cognate interaction between CD40L on T cells and CD40 on antigen-stimulated B cells, macrophage, and dendritic cells is critical for the development of a comprehensive immune response. The non-X-linked form of HIM syndrome is heterogeneous and appears in some cases to be a consequence of mutations in the AlD gene which encodes a B cell specific protein required for class switch recombination, somatic mutation, and germinal center formation. However, mutations in other unidentified genes are clearly the basis of the disease in a subset of patients. In this article, we review the essential features of the X-linked and non-X-linked forms of HIM syndrome and discuss the critical role the CD40:CD40L receptor-ligand pair plays in the pathogenesis of these immune deficiencies.
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Affiliation(s)
- A Bhushan
- Dept. of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway 08854, USA
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12
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Zonana J, Elder ME, Schneider LC, Orlow SJ, Moss C, Golabi M, Shapira SK, Farndon PA, Wara DW, Emmal SA, Ferguson BM. A novel X-linked disorder of immune deficiency and hypohidrotic ectodermal dysplasia is allelic to incontinentia pigmenti and due to mutations in IKK-gamma (NEMO). Am J Hum Genet 2000; 67:1555-62. [PMID: 11047757 PMCID: PMC1287930 DOI: 10.1086/316914] [Citation(s) in RCA: 360] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2000] [Accepted: 10/13/2000] [Indexed: 11/04/2022] Open
Abstract
Hypohidrotic ectodermal dysplasia (HED), a congenital disorder of teeth, hair, and eccrine sweat glands, is usually inherited as an X-linked recessive trait, although rarer autosomal dominant and recessive forms exist. We have studied males from four families with HED and immunodeficiency (HED-ID), in which the disorder segregates as an X-linked recessive trait. Affected males manifest dysgammaglobulinemia and, despite therapy, have significant morbidity and mortality from recurrent infections. Recently, mutations in IKK-gamma (NEMO) have been shown to cause familial incontinentia pigmenti (IP). Unlike HED-ID, IP affects females and, with few exceptions, causes male prenatal lethality. IKK-gamma is required for the activation of the transcription factor known as "nuclear factor kappa B" and plays an important role in T and B cell function. We hypothesize that "milder" mutations at this locus may cause HED-ID. In all four families, sequence analysis reveals exon 10 mutations affecting the carboxy-terminal end of the IKK-gamma protein, a domain believed to connect the IKK signalsome complex to upstream activators. The findings define a new X-linked recessive immunodeficiency syndrome, distinct from other types of HED and immunodeficiency syndromes. The data provide further evidence that the development of ectodermal appendages is mediated through a tumor necrosis factor/tumor necrosis factor receptor-like signaling pathway, with the IKK signalsome complex playing a significant role.
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Affiliation(s)
- J Zonana
- Department of Molecular and Medical Genetics, Oregon Health Sciences University, Portland, OR 97221, USA.
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