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He YJ, Lu G, Xu BJ, Mao QZ, Qi YH, Jiao GY, Weng HT, Tian YZ, Huang HJ, Zhang CX, Chen JP, Li JM. Maintenance of persistent transmission of a plant arbovirus in its insect vector mediated by the Toll-Dorsal immune pathway. Proc Natl Acad Sci U S A 2024; 121:e2315982121. [PMID: 38536757 PMCID: PMC10998634 DOI: 10.1073/pnas.2315982121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 03/01/2024] [Indexed: 04/08/2024] Open
Abstract
Throughout evolution, arboviruses have developed various strategies to counteract the host's innate immune defenses to maintain persistent transmission. Recent studies have shown that, in addition to bacteria and fungi, the innate Toll-Dorsal immune system also plays an essential role in preventing viral infections in invertebrates. However, whether the classical Toll immune pathway is involved in maintaining the homeostatic process to ensure the persistent and propagative transmission of arboviruses in insect vectors remain unclear. In this study, we revealed that the transcription factor Dorsal is actively involved in the antiviral defense of an insect vector (Laodelphax striatellus) by regulating the target gene, zinc finger protein 708 (LsZN708), which mediates downstream immune-related effectors against infection with the plant virus (Rice stripe virus, RSV). In contrast, an antidefense strategy involving the use of the nonstructural-protein (NS4) to antagonize host antiviral defense through competitive binding to Dorsal from the MSK2 kinase was employed by RSV; this competitive binding inhibited Dorsal phosphorylation and reduced the antiviral response of the host insect. Our study revealed the molecular mechanism through which Toll-Dorsal-ZN708 mediates the maintenance of an arbovirus homeostasis in insect vectors. Specifically, ZN708 is a newly documented zinc finger protein targeted by Dorsal that mediates the downstream antiviral response. This study will contribute to our understanding of the successful transmission and spread of arboviruses in plant or invertebrate hosts.
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Affiliation(s)
- Yu-Juan He
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Gang Lu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Bo-Jie Xu
- School of Basic Medical Sciences, Health Science Center, Ningbo University, Ningbo315211, China
| | - Qian-Zhuo Mao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Yu-Hua Qi
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Gao-Yang Jiao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Hai-Tao Weng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Yan-Zhen Tian
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Hai-Jian Huang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Chuan-Xi Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Jian-Ping Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
| | - Jun-Min Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo315211, China
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Andrianova EP, Marmion RA, Shvartsman SY, Zhulin IB. Evolutionary history of MEK1 illuminates the nature of deleterious mutations. Proc Natl Acad Sci U S A 2023; 120:e2304184120. [PMID: 37579140 PMCID: PMC10450672 DOI: 10.1073/pnas.2304184120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 07/24/2023] [Indexed: 08/16/2023] Open
Abstract
Mutations in signal transduction pathways lead to various diseases including cancers. MEK1 kinase, encoded by the human MAP2K1 gene, is one of the central components of the MAPK pathway and more than a hundred somatic mutations in the MAP2K1 gene were identified in various tumors. Germline mutations deregulating MEK1 also lead to congenital abnormalities, such as the cardiofaciocutaneous syndrome and arteriovenous malformation. Evaluating variants associated with a disease is a challenge, and computational genomic approaches aid in this process. Establishing evolutionary history of a gene improves computational prediction of disease-causing mutations; however, the evolutionary history of MEK1 is not well understood. Here, by revealing a precise evolutionary history of MEK1, we construct a well-defined dataset of MEK1 metazoan orthologs, which provides sufficient depth to distinguish between conserved and variable amino acid positions. We matched known and predicted disease-causing and benign mutations to evolutionary changes observed in corresponding amino acid positions and found that all known and many suspected disease-causing mutations are evolutionarily intolerable. We selected several variants that cannot be unambiguously assessed by automated prediction tools but that are confidently identified as "damaging" by our approach, for experimental validation in Drosophila. In all cases, evolutionary intolerant variants caused increased mortality and severe defects in fruit fly embryos confirming their damaging nature. We anticipate that our analysis will serve as a blueprint to help evaluate known and novel missense variants in MEK1 and that our approach will contribute to improving automated tools for disease-associated variant interpretation.
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Affiliation(s)
- Ekaterina P. Andrianova
- Department of Microbiology, The Ohio State University, Columbus, OH43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH43210
| | - Robert A. Marmion
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ08544
| | - Stanislav Y. Shvartsman
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ08544
- Department of Molecular Biology, Princeton University, Princeton, NJ08544
- Flatiron Institute, Simons Foundation, New York, NY10010
| | - Igor B. Zhulin
- Department of Microbiology, The Ohio State University, Columbus, OH43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH43210
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Bidoli C, Miccoli A, Buonocore F, Fausto AM, Gerdol M, Picchietti S, Scapigliati G. Transcriptome Analysis Reveals Early Hemocyte Responses upon In Vivo Stimulation with LPS in the Stick Insect Bacillus rossius (Rossi, 1788). INSECTS 2022; 13:insects13070645. [PMID: 35886821 PMCID: PMC9316843 DOI: 10.3390/insects13070645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/13/2022] [Accepted: 07/14/2022] [Indexed: 02/04/2023]
Abstract
Simple Summary Non-model insect species such as B. rossius suffer from a profound gap of knowledge regarding the temporal progression of physiological responses following the challenge with bacterial pathogens or cell wall components thereof. The reason for this mostly lies in the lack of genomic/transcriptomic resources, which would provide an unparalleled in-depth capacity in the analysis of molecular, biochemical, and metabolic mechanisms. We present a high-quality transcriptome obtained from high-coverage sequencing of hemocytes harvested from adult stick insect specimens both pre- and post-LPS stimulation. Such a resource served as the basis for a stringent differential gene expression and functional enrichment analyses, the results of which were characterized and discussed in depth. Selected transcripts encoding for C-type lectins and ML-domain containing proteins were further investigated from a phylogenetic perspective. Overall, these findings shed light on the physiological responses driven by a short-term LPS stimulation in the European stick insect. Abstract Despite a growing number of non-model insect species is being investigated in recent years, a greater understanding of their physiology is prevented by the lack of genomic resources. This is the case of the common European stick insect Bacillus rossius (Rossi, 1788): in this species, some knowledge is available on hemocyte-related defenses, but little is known about the physiological changes occurring in response to natural or experimental challenges. Here, the transcriptional signatures of adult B. rossius hemocytes were investigated after a short-term (2 h) LPS stimulation in vivo: a total of 2191 differentially expressed genes, mostly involved in proteolysis and carbohydrate and lipid metabolic processes, were identified in the de novo assembled transcriptome and in-depth discussed. Overall, the significant modulation of immune signals—such as C-type lectins, ML domain-containing proteins, serpins, as well as Toll signaling-related molecules—provide novel information on the early progression of LPS-induced responses in B. rossius.
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Affiliation(s)
- Carlotta Bidoli
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy; (C.B.); (M.G.)
| | - Andrea Miccoli
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (F.B.); (A.M.F.); (S.P.); (G.S.)
- Correspondence:
| | - Francesco Buonocore
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (F.B.); (A.M.F.); (S.P.); (G.S.)
| | - Anna Maria Fausto
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (F.B.); (A.M.F.); (S.P.); (G.S.)
| | - Marco Gerdol
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy; (C.B.); (M.G.)
| | - Simona Picchietti
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (F.B.); (A.M.F.); (S.P.); (G.S.)
| | - Giuseppe Scapigliati
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (F.B.); (A.M.F.); (S.P.); (G.S.)
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Hegde S, Sreejan A, Gadgil CJ, Ratnaparkhi GS. SUMOylation of Dorsal attenuates Toll/NF-κB signaling. Genetics 2022; 221:iyac081. [PMID: 35567478 PMCID: PMC9252280 DOI: 10.1093/genetics/iyac081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 05/03/2022] [Indexed: 11/29/2022] Open
Abstract
In Drosophila, Toll/NF-κB signaling plays key roles in both animal development and in host defense. The activation, intensity, and kinetics of Toll signaling are regulated by posttranslational modifications such as phosphorylation, SUMOylation, or ubiquitination that target multiple proteins in the Toll/NF-κB cascade. Here, we have generated a CRISPR-Cas9 edited Dorsal (DL) variant that is SUMO conjugation resistant. Intriguingly, embryos laid by dlSCR mothers overcome dl haploinsufficiency and complete the developmental program. This ability appears to be a result of higher transcriptional activation by DLSCR. In contrast, SUMOylation dampens DL transcriptional activation, ultimately conferring robustness to the dorso-ventral program. In the larval immune response, dlSCR animals show an increase in crystal cell numbers, stronger activation of humoral defense genes, and high cactus levels. A mathematical model that evaluates the contribution of the small fraction of SUMOylated DL (1-5%) suggests that it acts to block transcriptional activation, which is driven primarily by DL that is not SUMO conjugated. Our findings define SUMO conjugation as an important regulator of the Toll signaling cascade, in both development and host defense. Our results broadly suggest that SUMO attenuates DL at the level of transcriptional activation. Furthermore, we hypothesize that SUMO conjugation of DL may be part of a Ubc9-dependent mechanism that restrains Toll/NF-κB signaling.
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Affiliation(s)
- Sushmitha Hegde
- Biology, Indian Institute of Science Education & Research, Pune 411008, India
| | - Ashley Sreejan
- Chemical Engineering and Process Development Division, CSIR—National Chemical Laboratory, Pune 411008, India
| | - Chetan J Gadgil
- Chemical Engineering and Process Development Division, CSIR—National Chemical Laboratory, Pune 411008, India
- CSIR—Institute of Genomics and Integrative Biology, New Delhi 110020, India
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Expression and Function of Toll Pathway Components in the Early Development of the Wasp Nasonia vitripennis. J Dev Biol 2022; 10:jdb10010007. [PMID: 35225961 PMCID: PMC8883978 DOI: 10.3390/jdb10010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/20/2022] [Accepted: 01/22/2022] [Indexed: 11/22/2022] Open
Abstract
The Toll signaling pathway is the main source of embryonic DV polarity in the fly Drosophila melanogaster. This pathway appears to have been co-opted from an ancestral innate immunity system within the insects and has been deployed in different ways among insect taxa. Here we report the expression and function of homologs of the important components of the D. melanogaster Toll pathway in the wasp Nasonia vitripennis. We found homologs for all the components; many components had one or more additional paralogs in the wasp relative the fly. We also found significant deviations in expression patterns of N. vitripennis homologs. Finally, we provide some preliminary functional analyses of the N. vitripennis homologs, where we find a mixture of conservation and divergence of function.
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Abstract
Circadian clocks are biochemical time-keeping machines that synchronize animal behavior and physiology with planetary rhythms. In Drosophila, the core components of the clock comprise a transcription/translation feedback loop and are expressed in seven neuronal clusters in the brain. Although it is increasingly evident that the clocks in each of the neuronal clusters are regulated differently, how these clocks communicate with each other across the circadian neuronal network is less clear. Here, we review the latest evidence that describes the physical connectivity of the circadian neuronal network . Using small ventral lateral neurons as a starting point, we summarize how one clock may communicate with another, highlighting the signaling pathways that are both upstream and downstream of these clocks. We propose that additional efforts are required to understand how temporal information generated in each circadian neuron is integrated across a neuronal circuit to regulate rhythmic behavior.
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Affiliation(s)
- Myra Ahmad
- Department of Pediatrics, Division of Medical Genetics, Dalhousie University, Halifax, NS, Canada
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
| | - Wanhe Li
- Laboratory of Genetics, The Rockefeller University, New York, NY, USA
| | - Deniz Top
- Department of Pediatrics, Division of Medical Genetics, Dalhousie University, Halifax, NS, Canada
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
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A reaction-diffusion network model predicts a dual role of Cactus/IκB to regulate Dorsal/NFκB nuclear translocation in Drosophila. PLoS Comput Biol 2021; 17:e1009040. [PMID: 34043616 PMCID: PMC8189453 DOI: 10.1371/journal.pcbi.1009040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 06/09/2021] [Accepted: 05/03/2021] [Indexed: 11/19/2022] Open
Abstract
Dorsal-ventral patterning of the Drosophila embryo depends on the NFκB superfamily transcription factor Dorsal (Dl). Toll receptor activation signals for degradation of the IκB inhibitor Cactus (Cact), leading to a ventral-to-dorsal nuclear Dl gradient. Cact is critical for Dl nuclear import, as it binds to and prevents Dl from entering the nuclei. Quantitative analysis of cact mutants revealed an additional Cact function to promote Dl nuclear translocation in ventral regions of the embryo. To investigate this dual Cact role, we developed a predictive model based on a reaction-diffusion regulatory network. This network distinguishes non-uniform Toll-dependent Dl nuclear import and Cact degradation, from the Toll-independent processes of Cact degradation and reversible nuclear-cytoplasmic Dl flow. In addition, it incorporates translational control of Cact levels by Dl. Our model successfully reproduces wild-type data and emulates the Dl nuclear gradient in mutant dl and cact allelic combinations. Our results indicate that the dual role of Cact depends on the dynamics of Dl-Cact trimers along the dorsal-ventral axis: In the absence of Toll activation, free Dl-Cact trimers retain Dl in the cytoplasm, limiting the flow of Dl into the nucleus; in ventral-lateral regions, Dl-Cact trimers are recruited by Toll activation into predominant signaling complexes and promote Dl nuclear translocation. Simulations suggest that the balance between Toll-dependent and Toll-independent processes are key to this dynamics and reproduce the full assortment of Cact effects. Considering the high evolutionary conservation of these pathways, our analysis should contribute to understanding NFκB/c-Rel activation in other contexts such as in the vertebrate immune system and disease. In Drosophila, Toll pathway establishes spatially distinct gene expression territories that define the embryonic dorsal-ventral axis. Toll activation leads to degradation of the IκB inhibitor Cactus, releasing the NFκB superfamily transcription factor Dorsal for nuclear entry. Recently, quantitative analysis of cact mutants revealed that Cact displays an additional function to promote Dl nuclear translocation in ventral regions of the embryo. To understand this novel activity, we developed a predictive theoretical model that shows that the kinetics of Dorsal-Cactus complex formation prior to their recruitment to Toll-signaling complexes is an essential regulatory hub. Cactus controls the balance between the recruitment of these complexes by active Toll receptor and association-dissociation events that generate free Dorsal for direct nuclear import.
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Schloop AE, Bandodkar PU, Reeves GT. Formation, interpretation, and regulation of the Drosophila Dorsal/NF-κB gradient. Curr Top Dev Biol 2019; 137:143-191. [PMID: 32143742 DOI: 10.1016/bs.ctdb.2019.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The morphogen gradient of the transcription factor Dorsal in the early Drosophila embryo has become one of the most widely studied tissue patterning systems. Dorsal is a Drosophila homolog of mammalian NF-κB and patterns the dorsal-ventral axis of the blastoderm embryo into several tissue types by spatially regulating upwards of 100 zygotic genes. Recent studies using fluorescence microscopy and live imaging have quantified the Dorsal gradient and its target genes, which has paved the way for mechanistic modeling of the gradient. In this review, we describe the mechanisms behind the initiation of the Dorsal gradient and its regulation of target genes. The main focus of the review is a discussion of quantitative and computational studies of the Dl gradient system, including regulation of the Dl gradient. We conclude with a discussion of potential future directions.
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Affiliation(s)
- Allison E Schloop
- Genetics Program, North Carolina State University, Raleigh, NC, United States
| | - Prasad U Bandodkar
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, United States
| | - Gregory T Reeves
- Genetics Program, North Carolina State University, Raleigh, NC, United States; Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, United States.
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Germani F, Hain D, Sternlicht D, Moreno E, Basler K. The Toll pathway inhibits tissue growth and regulates cell fitness in an infection-dependent manner. eLife 2018; 7:39939. [PMID: 30451683 PMCID: PMC6279345 DOI: 10.7554/elife.39939] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/16/2018] [Indexed: 01/31/2023] Open
Abstract
The Toll pathway regulates the cellular response to infection via the transcriptional upregulation of antimicrobial peptides. In Drosophila, apart from its role in innate immunity, this pathway has also been reported to be important for the elimination of loser cells in a process referred to as cell competition, which can be locally triggered by secreted factors released from winner cells. In this work, we provide evidence that the inhibition of Toll signaling not only increases the fitness of loser cells, but also bestows a clonal growth advantage on wild-type cells. We further demonstrate that this growth advantage depends on basal infection levels since it is no longer present under axenic conditions but exacerbated upon intense pathogen exposure. Thus, the Toll pathway functions as a fine-tuned pro-apoptotic and anti-proliferative regulator, underlining the existence of a trade-off between innate immunity and growth during development.
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Affiliation(s)
- Federico Germani
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Daniel Hain
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Denise Sternlicht
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Eduardo Moreno
- Institute of Cell Biology, University of Bern, Bern, Switzerland.,Champalimaud Research Center Lisbon, Lisboa, Portugal
| | - Konrad Basler
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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Characterization of Site-Specific Phosphorylation of NF- κB p65 in Retinal Cells in Response to High Glucose and Cytokine Polarization. Mediators Inflamm 2018; 2018:3020675. [PMID: 29853786 PMCID: PMC5944204 DOI: 10.1155/2018/3020675] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/25/2018] [Indexed: 02/07/2023] Open
Abstract
Background Inflammation is an important contributor to the pathogenesis of diabetic retinopathy (DR). NF-κB is a master transcriptional regulator for numerous inflammatory genes. Although NF-κB is comprised of multiple subunits, p65 has received the most attention. However, the p65 subunit can be phosphorylated at numerous sites, for which the effects of DR-related conditions are not well characterized. Since dysregulation of NF-κB has been linked to chronic inflammation, the current study examines site-specific p65 phosphorylation in retinal cells exposed to high glucose and investigates the effects of cytokine polarization. Methods Phosphorylation of NF-κB p65 sites was examined in human primary retinal endothelial cells (HREC) and MIO-M1 Müller cells after exposure to high glucose (HG) and pro- or anti-inflammatory cytokines. Related downstream gene activation was selectively measured by real-time RT-PCR, ELISA, and/or Western blot. Results HG exposure resulted in differential phosphorylation of p65 subunit sites between HREC and Müller cells. Proinflammatory cytokines further increased phosphorylation of these sites and additional sites that were not altered in HG. In contrast, IL-4 exhibited a suppressive effect on the phosphorylation of p65 sites in both cell types and promoted IκBα expression. Downstream inflammatory mediators were increased in response to proinflammatory cytokine treatment versus HG exposure. IL-4 inhibited proinflammatory cytokines, while IL-10 was enhanced despite HG exposure. Conclusion The current study is the first to characterize HG-induced NF-κB p65 phosphorylation after cytokine polarization. By understanding NF-κB phosphorylation and cytokine influence during hyperglycemic conditions, intervention points can be identified for early-stage treatment of DR.
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11
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Carrell SN, O'Connell MD, Jacobsen T, Pomeroy AE, Hayes SM, Reeves GT. A facilitated diffusion mechanism establishes the Drosophila Dorsal gradient. Development 2017; 144:4450-4461. [PMID: 29097443 DOI: 10.1242/dev.155549] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/23/2017] [Indexed: 12/31/2022]
Abstract
The transcription factor NF-κB plays an important role in the immune system, apoptosis and inflammation. Dorsal, a Drosophila homolog of NF-κB, patterns the dorsal-ventral axis in the blastoderm embryo. During this stage, Dorsal is sequestered outside the nucleus by the IκB homolog Cactus. Toll signaling on the ventral side breaks the Dorsal/Cactus complex, allowing Dorsal to enter the nucleus to regulate target genes. Fluorescent data show that Dorsal accumulates on the ventral side of the syncytial blastoderm. Here, we use modeling and experimental studies to show that this accumulation is caused by facilitated diffusion, or shuttling, of the Dorsal/Cactus complex. We also show that active Toll receptors are limiting in wild-type embryos, which is a key factor in explaining global Dorsal gradient formation. Our results suggest that shuttling is necessary for viability of embryos from mothers with compromised dorsal levels. Therefore, Cactus not only has the primary role of regulating Dorsal nuclear import, but also has a secondary role in shuttling. Given that this mechanism has been found in other, independent, systems, we suggest that it might be more prevalent than previously thought.
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Affiliation(s)
- Sophia N Carrell
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27605, USA
| | - Michael D O'Connell
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27605, USA
| | - Thomas Jacobsen
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27605, USA
| | - Amy E Pomeroy
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27605, USA
| | - Stephanie M Hayes
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27605, USA
| | - Gregory T Reeves
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27605, USA
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12
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Lee E, Lee TA, Kim JH, Park A, Ra EA, Kang S, Choi HJ, Choi JL, Huh HD, Lee JE, Lee S, Park B. CNBP acts as a key transcriptional regulator of sustained expression of interleukin-6. Nucleic Acids Res 2017; 45:3280-3296. [PMID: 28168305 PMCID: PMC5389554 DOI: 10.1093/nar/gkx071] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/26/2017] [Indexed: 12/17/2022] Open
Abstract
The transcription of inflammatory genes is an essential step in host defense activation. Here, we show that cellular nucleic acid-binding protein (CNBP) acts as a transcription regulator that is required for activating the innate immune response. We identified specific CNBP-binding motifs present in the promoter region of sustained inflammatory cytokines, thus, directly inducing the expression of target genes. In particular, lipopolysaccharide (LPS) induced cnbp expression through an NF-κB-dependent manner and a positive autoregulatory mechanism, which enables prolonged il-6 gene expression. This event depends strictly on LPS-induced CNBP nuclear translocation through phosphorylation-mediated dimerization. Consequently, cnbp-depleted zebrafish are highly susceptible to Shigella flexneri infection in vivo. Collectively, these observations identify CNBP as a key transcriptional regulator required for activating and maintaining the immune response.
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Affiliation(s)
- Eunhye Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
- These authors contributed equally to the paper as first authors
| | - Taeyun A. Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
- These authors contributed equally to the paper as first authors
| | - Ji Hyun Kim
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06351, South Korea
- These authors contributed equally to the paper as first authors
| | - Areum Park
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Eun A. Ra
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Sujin Kang
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Hyun jin Choi
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Junhee L. Choi
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Hyunbin D. Huh
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Ji Eun Lee
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06351, South Korea
- Samsung Genome Institute (SGI), Samsung Medical Center, Seoul 06351, South Korea
- To whom correspondence should be addressed. Tel: +82 2 2123 5655; Fax: +82 2 312 5657; . Correspondence may also be addressed to Ji Eun Lee. Tel: +82 2 3410 6129; Fax: +82 2 3410 0534; . Correspondence may also be addressed to Sungwook Lee. Tel: +82 31 920 2537; Fax: +82 31 920 2542;
| | - Sungwook Lee
- Cancer Immunology Branch, Research Institute, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 10408, South Korea
- To whom correspondence should be addressed. Tel: +82 2 2123 5655; Fax: +82 2 312 5657; . Correspondence may also be addressed to Ji Eun Lee. Tel: +82 2 3410 6129; Fax: +82 2 3410 0534; . Correspondence may also be addressed to Sungwook Lee. Tel: +82 31 920 2537; Fax: +82 31 920 2542;
| | - Boyoun Park
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
- To whom correspondence should be addressed. Tel: +82 2 2123 5655; Fax: +82 2 312 5657; . Correspondence may also be addressed to Ji Eun Lee. Tel: +82 2 3410 6129; Fax: +82 2 3410 0534; . Correspondence may also be addressed to Sungwook Lee. Tel: +82 31 920 2537; Fax: +82 31 920 2542;
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Tinoco-Nunes B, Telleria EL, da Silva-Neves M, Marques C, Azevedo-Brito DA, Pitaluga AN, Traub-Csekö YM. The sandfly Lutzomyia longipalpis LL5 embryonic cell line has active Toll and Imd pathways and shows immune responses to bacteria, yeast and Leishmania. Parasit Vectors 2016; 9:222. [PMID: 27098567 PMCID: PMC4839078 DOI: 10.1186/s13071-016-1507-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 04/12/2016] [Indexed: 11/23/2022] Open
Abstract
Background Lutzomyia longipalpis is the main vector of visceral leishmaniasis in Latin America. Sandfly immune responses are poorly understood. In previous work we showed that these vector insects respond to bacterial infections by modulating a defensin gene expression and activate the Imd pathway in response to Leishmania infection. Aspects of innate immune pathways in insects (including mosquito vectors of human diseases) have been revealed by studying insect cell lines, and we have previously demonstrated antiviral responses in the L. longipalpis embryonic cell line LL5. Methods The expression patterns of antimicrobial peptides (AMPs) and transcription factors were evaluated after silencing the repressors of the Toll pathway (cactus) and Imd pathway (caspar). AMPs and transcription factor expression patterns were also evaluated after challenge with heat-killed bacteria, heat-killed yeast, or live Leishmania. Results These studies showed that LL5 cells have active Toll and Imd pathways, since they displayed an increased expression of AMP genes following silencing of the repressors cactus and caspar, respectively. These pathways were also activated by challenges with bacteria, yeast and Leishmania infantum chagasi. Conclusions We demonstrated that L. longipalpis LL5 embryonic cells respond to immune stimuli and are therefore a good model to study the immunological pathways of this important vector of leishmaniasis.
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Affiliation(s)
- Bruno Tinoco-Nunes
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
| | - Erich Loza Telleria
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
| | - Monique da Silva-Neves
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
| | - Christiane Marques
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
| | - Daisy Aline Azevedo-Brito
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
| | - André Nóbrega Pitaluga
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
| | - Yara Maria Traub-Csekö
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
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Li YX, Dijkers PF. Specific Calcineurin Isoforms Are Involved in Drosophila Toll Immune Signaling. THE JOURNAL OF IMMUNOLOGY 2014; 194:168-76. [DOI: 10.4049/jimmunol.1401080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Cheng D, Qian W, Wang Y, Meng M, Wei L, Li Z, Kang L, Peng J, Xia Q. Nuclear import of transcription factor BR-C is mediated by its interaction with RACK1. PLoS One 2014; 9:e109111. [PMID: 25280016 PMCID: PMC4184850 DOI: 10.1371/journal.pone.0109111] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/29/2014] [Indexed: 11/18/2022] Open
Abstract
The transcription factor Broad Complex (BR-C) is an early ecdysone response gene in insects and contains two types of domains: two zinc finger domains for the activation of gene transcription and a Bric-a-brac/Tramtrack/Broad complex (BTB) domain for protein-protein interaction. Although the mechanism of zinc finger-mediated gene transcription is well studied, the partners interacting with the BTB domain of BR-C has not been elucidated until now. Here, we performed a yeast two-hybrid screen using the BTB domain of silkworm BR-C as bait and identified the receptor for activated C-kinase 1 (RACK1), a scaffolding/anchoring protein, as the novel partner capable of interacting with BR-C. The interaction between BR-C and RACK1 was further confirmed by far-western blotting and pull-down assays. Importantly, the disruption of this interaction, via RNAi against the endogenous RACK1 gene or deletion of the BTB domain, abolished the nuclear import of BR-C in BmN4 cells. In addition, RNAi against the endogenous PKC gene as well as phosphorylation-deficient mutation of the predicted PKC phosphorylation sites at either Ser373 or Thr406 in BR-C phenocopied RACK1 RNAi and altered the nuclear localization of BR-C. However, when BTB domain was deleted, phosphorylation mimics of either Ser373 or Thr406 had no effect on the nuclear import of BR-C. Moreover, mutating the PKC phosphorylation sites at Ser373 and Thr406 or deleting the BTB domain significantly decreased the transcriptional activation of a BR-C target gene. Given that RACK1 is necessary for recruiting PKC to close and phosphorylate target proteins, we suggest that the PKC-mediated phosphorylation and nuclear import of BR-C is determined by its interaction with RACK1. This novel finding will be helpful for further deciphering the mechanism underlying the role of BR-C proteins during insect development.
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Affiliation(s)
- Daojun Cheng
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Wenliang Qian
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Yonghu Wang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Meng Meng
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Ling Wei
- School of Life Science, Southwest University, Chongqing, China
| | - Zhiqing Li
- Laboratory of Silkworm Science, Kyushu University Graduate School of Bioresource and Bioenvironmental Sciences, Fukuoka, Japan
| | - Lixia Kang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Jian Peng
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Qingyou Xia
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
- * E-mail:
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Wisotzkey RG, Quijano JC, Stinchfield MJ, Newfeld SJ. New gene evolution in the bonus-TIF1-γ/TRIM33 family impacted the architecture of the vertebrate dorsal-ventral patterning network. Mol Biol Evol 2014; 31:2309-21. [PMID: 24881051 DOI: 10.1093/molbev/msu175] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Uncovering how a new gene acquires its function and understanding how the function of a new gene influences existing genetic networks are important topics in evolutionary biology. Here, we demonstrate nonconservation for the embryonic functions of Drosophila Bonus and its newest vertebrate relative TIF1-γ/TRIM33. We showed previously that TIF1-γ/TRIM33 functions as an ubiquitin ligase for the Smad4 signal transducer and antagonizes the Bone Morphogenetic Protein (BMP) signaling network underlying vertebrate dorsal-ventral axis formation. Here, we show that Bonus functions as an agonist of the Decapentaplegic (Dpp) signaling network underlying dorsal-ventral axis formation in flies. The absence of conservation for the roles of Bonus and TIF1-γ/TRIM33 reveals a shift in the dorsal-ventral patterning networks of flies and mice, systems that were previously considered wholly conserved. The shift occurred when the new gene TIF1-γ/TRIM33 replaced the function of the ubiquitin ligase Nedd4L in the lineage leading to vertebrates. Evidence of this replacement is our demonstration that Nedd4 performs the function of TIF1-γ/TRIM33 in flies during dorsal-ventral axis formation. The replacement allowed vertebrate Nedd4L to acquire novel functions as a ubiquitin ligase of vertebrate-specific Smad proteins. Overall our data reveal that the architecture of the Dpp/BMP dorsal-ventral patterning network continued to evolve in the vertebrate lineage, after separation from flies, via the incorporation of new genes.
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Affiliation(s)
- Robert G Wisotzkey
- Department of Biological Sciences, California State University, East Bay
| | - Janine C Quijano
- Department of Biological Sciences, California State University, East BaySchool of Life Sciences, Arizona State University
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Stein DS, Stevens LM. Maternal control of the Drosophila dorsal-ventral body axis. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 3:301-30. [PMID: 25124754 DOI: 10.1002/wdev.138] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 03/24/2014] [Accepted: 04/07/2014] [Indexed: 12/14/2022]
Abstract
UNLABELLED The pathway that generates the dorsal-ventral (DV) axis of the Drosophila embryo has been the subject of intense investigation over the previous three decades. The initial asymmetric signal originates during oogenesis by the movement of the oocyte nucleus to an anterior corner of the oocyte, which establishes DV polarity within the follicle through signaling between Gurken, the Drosophila Transforming Growth Factor (TGF)-α homologue secreted from the oocyte, and the Drosophila Epidermal Growth Factor Receptor (EGFR) that is expressed by the follicular epithelium cells that envelop the oocyte. Follicle cells that are not exposed to Gurken follow a ventral fate and express Pipe, a sulfotransferase that enzymatically modifies components of the inner vitelline membrane layer of the eggshell, thereby transferring DV spatial information from the follicle to the egg. These ventrally sulfated eggshell proteins comprise a localized cue that directs the ventrally restricted formation of the active Spätzle ligand within the perivitelline space between the eggshell and the embryonic membrane. Spätzle activates Toll, a transmembrane receptor in the embryonic membrane. Transmission of the Toll signal into the embryo leads to the formation of a ventral-to-dorsal gradient of the transcription factor Dorsal within the nuclei of the syncytial blastoderm stage embryo. Dorsal controls the spatially specific expression of a large constellation of zygotic target genes, the Dorsal gene regulatory network, along the embryonic DV circumference. This article reviews classic studies and integrates them with the details of more recent work that has advanced our understanding of the complex pathway that establishes Drosophila embryo DV polarity. For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- David S Stein
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
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Fontenele M, Lim B, Oliveira D, Buffolo M, Perlman DH, Schupbach T, Araujo H. Calpain A modulates Toll responses by limited Cactus/IκB proteolysis. Mol Biol Cell 2013; 24:2966-80. [PMID: 23864715 PMCID: PMC3771957 DOI: 10.1091/mbc.e13-02-0113] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Calcium-dependent cysteine proteases of the calpain family are modulatory proteases that cleave their substrates in a limited manner. Among their substrates, calpains target vertebrate and invertebrate IκB proteins. Because proteolysis by calpains potentially generates novel protein functions, it is important to understand how this affects NFκB activity. We investigate the action of Calpain A (CalpA) on the Drosophila melanogaster IκB homologue Cactus in vivo. CalpA alters the absolute amounts of Cactus protein. Our data indicate, however, that CalpA uses additional mechanisms to regulate NFκB function. We provide evidence that CalpA interacts physically with Cactus, recognizing a Cactus pool that is not bound to Dorsal, a fly NFκB/Rel homologue. We show that proteolytic cleavage by CalpA generates Cactus fragments lacking an N-terminal region required for Toll responsiveness. These fragments are generated in vivo and display properties distinct from those of full-length Cactus. We propose that CalpA targets free Cactus, which is incorporated into and modulates Toll-responsive complexes in the embryo and immune system.
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Affiliation(s)
- Marcio Fontenele
- Institute for Biomedical Sciences, Federal University of Rio de Janeiro, CEP 21941-902 Rio de Janeiro, Brazil Chemistry Institute, Federal University of Rio de Janeiro, CEP 21941-902 Rio de Janeiro, Brazil Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, Brazil Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 Princeton Collaborative Proteomics and Mass Spectrometry Center, Princeton University, Princeton, NJ 08544 Molecular Biology Department, Princeton University, Princeton, NJ 08544 Howard Hughes Medical Institute, Chevy Chase, MD 20815
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Hochrainer K, Racchumi G, Anrather J. Site-specific phosphorylation of the p65 protein subunit mediates selective gene expression by differential NF-κB and RNA polymerase II promoter recruitment. J Biol Chem 2012; 288:285-93. [PMID: 23100252 DOI: 10.1074/jbc.m112.385625] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Phosphorylation of NF-κB plays an important role in modulating transcriptional activity of NF-κB independently of inhibitor of κB (IκB) proteins. For the p65 subunit, multiple phosphorylation sites have been mapped in and adjacent to both the N-terminal Rel homology domain and the C-terminal transactivation domain. Their impact on NF-κB-dependent transcription, however, has never been assessed at a broader level. In this study, we evaluate the importance of differential p65 phosphorylation on four serine acceptor sites in the Rel homology domain for the expression of an array of NF-κB-dependent genes in endothelial cells. We find that inhibition of p65 phosphorylation on these serine residues targets NF-κB activity to distinctive gene subsets in a κB enhancer element-specific context. We show that the phosphorylation-dependent alterations in gene and protein expression are reflective of the amount of p65 and phosphorylated RNA polymerase II (p-RNAP II) bound to respective gene promoter regions. Depending on the gene subset, impaired gene expression was either a result of decreased p65 promoter recruitment or of a failure of bound p65 to recruit p-RNAP II. In conclusion, our findings demonstrate that site-specific p65 phosphorylation targets NF-κB activity to particular gene subsets on a global level by influencing p65 and p-RNAP II promoter recruitment.
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Affiliation(s)
- Karin Hochrainer
- Department of Neurology and Neuroscience, Division of Neurobiology, Weill Cornell Medical College, New York, New York 10065, USA
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20
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Pejanovic N, Hochrainer K, Liu T, Aerne BL, Soares MP, Anrather J. Regulation of nuclear factor κB (NF-κB) transcriptional activity via p65 acetylation by the chaperonin containing TCP1 (CCT). PLoS One 2012; 7:e42020. [PMID: 22860050 PMCID: PMC3409233 DOI: 10.1371/journal.pone.0042020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 07/02/2012] [Indexed: 01/24/2023] Open
Abstract
The NF-κB family member p65 is central to inflammation and immunity. The purpose of this study was to identify and characterize evolutionary conserved genes modulating p65 transcriptional activity. Using an RNAi screening approach, we identified chaperonin containing TCP1 subunit η (CCTη) as a regulator of Drosophila NF-κB proteins, Dorsal and Dorsal-related immunity factor (Dif). CCTη was also found to regulate NF-κB-driven transcription in mammalian cells, acting in a promoter-specific context, downstream of IκB kinase (IKK). CCTη knockdown repressed IκBα and CXCL2/MIP2 transcription during the early phase of NF-κB activation while impairing the termination of CCL5/RANTES and CXCL10/IP10 transcription. The latter effect was associated with increased DNA binding and reduced p65 acetylation, presumably by altering the activity of histone acetyltransferase CREB-binding protein (CBP). We identified p65 lysines (K) 122 and 123 as target residues mediating the CCTη-driven termination of NF-κB-dependent transcription. We propose that CCTη regulates NF-κB activity in a manner that resolves inflammation.
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Affiliation(s)
- Nadja Pejanovic
- Division of Neurobiology, Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York, United States of America
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Abstract
The vast majority of research on nuclear factor κB (NF-κB) signaling in the past 25 years has focused on its roles in normal and disease-related processes in vertebrates, especially mice and humans. Recent genome and transcriptome sequencing efforts have shown that homologs of NF-κB transcription factors, inhibitor of NF-κB (IκB) proteins, and IκB kinases are present in a variety of invertebrates, including several in phyla simpler than Arthropoda, the phylum containing insects such Drosophila. Moreover, many invertebrates also contain genes encoding homologs of upstream signaling proteins in the Toll-like receptor signaling pathway, which is well-known for its downstream activation of NF-κB for innate immunity. This review describes what we now know or can infer and speculate about the evolution of the core elements of NF-κB signaling as well as the biological processes controlled by NF-κB in invertebrates. Further research on NF-κB in invertebrates is likely to uncover information about the evolutionary origins of this key human signaling pathway and may have relevance to our management of the responses of ecologically and economically important organisms to environmental and adaptive pressures.
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Affiliation(s)
- Thomas D Gilmore
- Department of Biology, Boston University, Boston, MA 02215, USA.
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Schiffmann Y. Maternal-effect genes as the recording genes of Turing-Child patterns: Sequential compartmentalization in Drosophila. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 109:16-32. [DOI: 10.1016/j.pbiomolbio.2012.04.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 04/18/2012] [Indexed: 10/28/2022]
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Endocytosis is required for Toll signaling and shaping of the Dorsal/NF-kappaB morphogen gradient during Drosophila embryogenesis. Proc Natl Acad Sci U S A 2010; 107:18028-33. [PMID: 20921412 DOI: 10.1073/pnas.1009157107] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Dorsoventral cell fate in the Drosophila embryo is specified by activation of the Toll receptor, leading to a ventral-to-dorsal gradient across nuclei of the NF-κB transcription factor Dorsal. Toll receptor has been investigated genetically, molecularly, and immunohistologically, but much less is known about its dynamics in living embryos. Using live imaging of fluorescent protein chimeras, we find that Toll is recruited from the plasma membrane to Rab5(+) early endosomes. The distribution of a constitutively active form of Toll, Toll(10b), is shifted from the plasma membrane to early endosomes. Inhibition of endocytosis on the ventral side of the embryo attenuates Toll signaling ventrally and causes Dorsal to accumulate on the dorsal side of the embryo, essentially inverting the dorsal/ventral axis. Conversely, enhancing endocytosis laterally greatly potentiates Toll signaling locally, altering the shape of the Dorsal gradient. Photoactivation and fluorescence recovery after photobleaching studies reveal that Toll exhibits extremely limited lateral diffusion within the plasma membrane, whereas Toll is highly compartmentalized in endosomes. When endocytosis is blocked ventrally, creating an ectopic dorsal signaling center, Toll is preferentially endocytosed at the ectopic signaling center. We propose that Toll signals from an endocytic compartment rather than the plasma membrane. Our studies reveal that endocytosis plays a pivotal role in the spatial regulation of Toll receptor activation and signaling and in the correct shaping of the nuclear Dorsal concentration gradient.
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Ganesan S, Aggarwal K, Paquette N, Silverman N. NF-κB/Rel proteins and the humoral immune responses of Drosophila melanogaster. Curr Top Microbiol Immunol 2010; 349:25-60. [PMID: 20852987 DOI: 10.1007/82_2010_107] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nuclear Factor-κB (NF-κB)/Rel transcription factors form an integral part of innate immune defenses and are conserved throughout the animal kingdom. Studying the function, mechanism of activation and regulation of these factors is crucial for understanding host responses to microbial infections. The fruit fly Drosophila melanogaster has proved to be a valuable model system to study these evolutionarily conserved NF-κB mediated immune responses. Drosophila combats pathogens through humoral and cellular immune responses. These humoral responses are well characterized and are marked by the robust production of a battery of anti-microbial peptides. Two NF-κB signaling pathways, the Toll and the IMD pathways, are responsible for the induction of these antimicrobial peptides. Signal transduction in these pathways is strikingly similar to that in mammalian TLR pathways. In this chapter, we discuss in detail the molecular mechanisms of microbial recognition, signal transduction and NF-κB regulation, in both the Toll and the IMD pathways. Similarities and differences relative to their mammalian counterparts are discussed, and recent advances in our understanding of the intricate regulatory networks in these NF-κB signaling pathways are also highlighted.
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Affiliation(s)
- Sandhya Ganesan
- Division of Infectious Diseases, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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Monie TP, Moncrieffe MC, Gay NJ. Structure and regulation of cytoplasmic adapter proteins involved in innate immune signaling. Immunol Rev 2009; 227:161-75. [PMID: 19120483 DOI: 10.1111/j.1600-065x.2008.00735.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Initiation of the innate immune response requires agonist recognition by a pathogen recognition receptor. Following ligand binding, conformational rearrangement of the receptor creates a molecular scaffold from which signal transduction is propagated via complex cellular signaling pathways. This in turn leads to the induction of a pro-inflammatory immune response. A critical component of these signaling pathways is the homotypic interaction of receptor and adapter proteins via specific protein interaction domains. Within the innate immune signaling cascade, homotypic interactions between members of the death domain family and the Toll/interleukin-1 receptor domain are particularly important. Here we discuss the current understanding of the molecular basis of these homotypic receptor:adapter interactions and their role in innate immune signal transduction.
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Affiliation(s)
- Tom P Monie
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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Silverman N, Paquette N, Aggarwal K. Specificity and signaling in the Drosophila immune response. INVERTEBRATE SURVIVAL JOURNAL : ISJ 2009; 6:163-174. [PMID: 21625362 PMCID: PMC3101770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The Drosophila immune response is characterized by the rapid and robust production of a battery of antimicrobial peptides immediately following infection. The genes encoding these antimicrobial peptides are controlled by two NF-κB signaling pathways that respond to microbial infection. The IMD pathway is triggered by DAP-type peptidoglycan, from the cell wall of most Gram-negative and certain Gram-positive bacteria, and activates the NF-κB precursor protein Relish. The Toll pathway, on the other hand, is stimulated by lysine-type peptidoglycan from many Gram-positive bacteria, β 1,3 glucans from many fungi, as well as by microbial proteases. Toll signaling leads to the activation and nuclear translocation of DIF or Dorsal, two other NF-κB homologs. This review presents our current understanding of the molecular mechanisms involved in microbial recognition and signal transduction in these two innate immune pathways.
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Affiliation(s)
- N Silverman
- University of Massachusetts Medical School, Worcester, USA
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Fontenele M, Carneiro K, Agrellos R, Oliveira D, Oliveira-Silva A, Vieira V, Negreiros E, Machado E, Araujo H. The Ca2+-dependent protease Calpain A regulates Cactus/I kappaB levels during Drosophila development in response to maternal Dpp signals. Mech Dev 2009; 126:737-51. [PMID: 19442719 DOI: 10.1016/j.mod.2009.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/24/2009] [Accepted: 04/27/2009] [Indexed: 11/15/2022]
Abstract
Regulation of NF kappaB activity is central to many processes during development and disease. Activation of NF kappaB family members depends on degradation of inhibitory I kappaB proteins. In Drosophila, a nuclear gradient of the NF kappaB/c-rel protein Dorsal subdivides the embryonic dorsal-ventral axis, defining the extent and location of mesodermal and ectodermal territories. Activation of the Toll pathway directs Dorsal nuclear translocation by inducing proteosomal degradation of the I kappaB homologue Cactus. Another mechanism that impacts on Dorsal activation involves the Toll-independent pathway, which regulates constitutive Cactus degradation. We have shown that the BMP protein Decapentaplegic (Dpp) inhibits Cactus degradation independent of Toll. Here we report on a novel element of this pathway: the calcium-dependent protease Calpain A. Calpain A knockdowns increase Cactus levels, shifting the Dorsal gradient and dorsal-ventral patterning. As shown for mammalian I kappaB, this effect requires PEST sequences in the Cactus C-terminus, implying a conserved role for calpains. Alteration of Calpain A or dpp results in similar effects on Dorsal target genes. Epistatic analysis confirms Calpain A activity is regulated by Dpp, indicating that Dpp signals increase Cactus levels through Calpain A inhibition, thereby interfering with Dorsal activation. This mechanism may allow coordination of Toll, BMP and Ca(2+) signals, conferring precision to Dorsal-target expression domains.
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Affiliation(s)
- M Fontenele
- Institute for Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
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Wiklund ML, Steinert S, Junell A, Hultmark D, Stöven S. The N-terminal half of the Drosophila Rel/NF-kappaB factor Relish, REL-68, constitutively activates transcription of specific Relish target genes. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2009; 33:690-6. [PMID: 19135474 DOI: 10.1016/j.dci.2008.12.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 11/30/2008] [Accepted: 12/05/2008] [Indexed: 05/14/2023]
Abstract
The Rel/NF-kappaB transcription factor Relish is a major regulator of the antimicrobial response in Drosophila. Upon immune challenge, Relish is cleaved to generate two fragments, the DNA-binding transcription factor REL-68 and the IkappaB-like REL-49. Using transgenic fly strains we show here that overexpression of REL-68 separately from REL-49 is sufficient to activate strong constitutive transcription of the Diptericin gene, but little constitutive or inducible transcription of Attacin and Cecropin, two other Relish target genes. Their transcription may therefore require additional modifications of Relish. However, phosphorylation of the conserved serine residue S431 is not involved in such modifications. This is unlike p65 and Dorsal, which are modulated by phosphorylation at their homologous site. In contrast to other IkappaB proteins, overexpression of REL-49 had no inhibitory effect on Relish-dependent transcription. Instead, we propose that the C-terminal IkappaB-like domain executes a scaffolding and recruiting function for full activation of Relish.
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29
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Moncrieffe MC, Grossmann JG, Gay NJ. Assembly of oligomeric death domain complexes during Toll receptor signaling. J Biol Chem 2008; 283:33447-54. [PMID: 18829464 DOI: 10.1074/jbc.m805427200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Drosophila Toll receptor is activated by the endogenous protein ligand Spätzle in response to microbial stimuli in immunity and spatial cues during embryonic development. Downstream signaling is mediated by the adaptor proteins Tube, the kinase Pelle, and the Drosophila homologue of myeloid differentiation primary response protein (dMyD88). Here we have characterized heterodimeric (dMyD88-Tube) and heterotrimeric (dMyD88-Tube-Pelle) death domain complexes. We show that both the heterodimeric and heterotrimeric complexes form kidney-shaped structures and that Tube is bivalent and has separate high affinity binding sites for dMyD88 and Pelle. Additionally we found no interaction between the isolated death domains of Pelle and dMyD88. These results indicate that the mode of assembly of the heterotrimeric dMyD88-Tube-Pelle complex downstream of the activated Toll receptor is unique. The measured dissociation constants for the interaction between the death domains of dMyD88 and Tube and of Pelle and a preformed dMyD88-Tube complex are used to propose a model of the early postreceptor events in Drosophila Toll receptor signaling.
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Affiliation(s)
- Martin C Moncrieffe
- Department of Biochemistry, Cambridge University, Cambridge CB2 1GA, United Kingdom.
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30
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Horner VL, Wolfner MF. Transitioning from egg to embryo: Triggers and mechanisms of egg activation. Dev Dyn 2008; 237:527-44. [DOI: 10.1002/dvdy.21454] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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31
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Hypo-phosphorylation leads to nuclear retention of NF-kappaB p65 due to impaired IkappaBalpha gene synthesis. FEBS Lett 2007; 581:5493-9. [PMID: 17991436 DOI: 10.1016/j.febslet.2007.10.056] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 09/27/2007] [Accepted: 10/28/2007] [Indexed: 11/20/2022]
Abstract
Subcellular localization guided by IkappaBalpha is crucial for regulation of nuclear factor-kappaB function. Here, we show that p65 Rel homology domain phosphorylation mutants are transported into the nucleus after IkappaBalpha degradation, but as a consequence of lower IkappaBalpha levels their relocation to the cytosol is blocked. We demonstrate that phosphorylation of residues S205, S276, and S281 of p65 is not required for interaction between p65 and IkappaBalpha, but is pivotal for regulating cellular IkappaBalpha levels by positively affecting gene synthesis. Our findings indicate that reduction of phosphorylation leads to nuclear retention of p65, which might be partly responsible for altered transcriptional behavior of p65 serine mutants.
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32
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DeLotto R, DeLotto Y, Steward R, Lippincott-Schwartz J. Nucleocytoplasmic shuttling mediates the dynamic maintenance of nuclear Dorsal levels during Drosophila embryogenesis. Development 2007; 134:4233-41. [PMID: 17978003 DOI: 10.1242/dev.010934] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In Drosophila, the NF-kappaB/REL family transcription factor, Dorsal, redistributes from the cytoplasm to nuclei, forming a concentration gradient across the dorsoventral axis of the embryo. Using live imaging techniques in conjunction with embryos expressing a chimeric Dorsal-GFP, we demonstrate that the redistribution of Dorsal from cytoplasm to nucleus is an extremely dynamic process. Nuclear Dorsal concentration changes continuously over time in all nuclei during interphase. While Dorsal appears to be nuclearly localized primarily in ventral nuclei, it is actively shuttling into and out of all nuclei, including nuclei on the dorsal side. Nuclear export is blocked by leptomycin B, a potent inhibitor of Exportin 1 (CRM1)-mediated nuclear export. We have developed a novel in vivo assay revealing the presence of a functional leucine-rich nuclear export signal within the carboxyterminal 44 amino acids of Dorsal. We also find that diffusion of Dorsal is partially constrained to cytoplasmic islands surrounding individual syncitial nuclei. A model is proposed in which the generation and maintenance of the Dorsal gradient is a consequence of an active process involving both restricted long-range diffusion and the balancing of nuclear import with nuclear export.
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Affiliation(s)
- Robert DeLotto
- Department of Molecular Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
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33
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Abstract
The nuclear factor kappa B (NF-kappaB) pathways in Drosophila are multi-component pathways, as in vertebrates, that regulate the expression of many genes responsible for the formation of dorsal-ventral polarity in the early embryo, the innate immune response to infection with Gram- negative and positive bacteria and fungi, the cellular immune response and hematopoiesis. Overactivation of the fly pathway can result in developmental defects, overproliferation of hemocytes and the formation of melanotic tumors or nodules. The extracellular events leading to the maturation of the ligand for initiation of the Drosophila NF-kappaB pathway is not conserved between flies and vertebrates, but the Toll receptor and downstream events are remarkably similar. NF-kappaB proteins have been identified in mollusks, and arthropods such as horseshoe crabs and beetles, indicating that this pathway has been established more than 500 million years ago. The fly NF-kappaB pathways are less complex than those in vertebrates, with the involvement of fewer proteins, but they are, nonetheless, just as important as their vertebrate counterparts for the life of the fly.
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Affiliation(s)
- S Minakhina
- Waksman Institute, Department of Molecular Biology and Biochemistry and the Cancer Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
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34
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Xylourgidis N, Roth P, Sabri N, Tsarouhas V, Samakovlis C. The nucleoporin Nup214 sequesters CRM1 at the nuclear rim and modulates NFkappaB activation in Drosophila. J Cell Sci 2006; 119:4409-19. [PMID: 17032737 DOI: 10.1242/jcs.03201] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CRM1-mediated protein export is an important determinant of the nuclear accumulation of many gene regulators. Here, we show that the NFkappaB transcription factor Dorsal is a substrate of CRM1 and requires the nucleoporin Nup214 for its nuclear translocation upon signaling. Nup214 bound to CRM1 directly and anchored it to the nuclear envelope. In nup214 mutants CRM1 accumulated in the nucleus and NES-protein export was enhanced. Nup214 formed complexes with Nup88 and CRM1 in vivo and Nup214 protected Nup88 from degradation at the nuclear rim. In turn, Nup88 was sufficient for targeting the complex to the nuclear pores. Overexpression experiments indicated that Nup214 alone attracts a fraction of CRM1 to the nuclear envelope but does not interfere with NES-GFP export. By contrast, overexpression of the Nup214-Nup88 complex trapped CRM1 and Dorsal to cytoplasmic foci and inhibited protein export and immune response activation. We hypothesize that variation in levels of the Nup214-Nup88 complex at the pore changes the amount of NPC-bound CRM1 and influences the relative strength and duration of NFkappaB signaling responses.
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Affiliation(s)
- Nikos Xylourgidis
- Department of Developmental Biology, Wenner-Gren Institute, Stockholm University, S-10691, Stockholm, Sweden
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35
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Tergaonkar V. NFkappaB pathway: a good signaling paradigm and therapeutic target. Int J Biochem Cell Biol 2006; 38:1647-53. [PMID: 16766221 DOI: 10.1016/j.biocel.2006.03.023] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/23/2006] [Accepted: 03/31/2006] [Indexed: 01/01/2023]
Abstract
NFkappaB was identified 20 years ago (Sen, R., & Baltimore, D. (1986) Cell, 46, 705-716) as a nuclear factor that binds the kappa light chain enhancer in B-cells (and hence, the name NFkappaB) and was shown to play roles in innate and adaptive immune responses. More recently, its role in many other cellular processes has become apparent. Perhaps, not surprisingly, deregulated activity of the NFkappaB pathway has been observed and linked to the progression of several human ailments, including cancers. Research in the last two decades has identified the major mechanisms of activation of this pathway and has documented the roles of the key players. Over 200 physiological stimuli are known to activate NFkappaB. These include bacterial and viral products, cellular receptors and ligands, mitogens and growth factors and physical and biochemical stress inducers. The major cellular targets of NFkappaB are chemokines, immune receptors, adhesion molecules, stress response genes, regulators of apoptosis, transcription factors, growth factors, enzymes and cell cycle regulators. In addition, NFkappaB is known to be important for transcription of several viral promoter/enhancers (e.g. HIV-1 and CMV). Given that, such a large number of stimuli can activate NFkappaB, which in turn activates an equally large number of target genes, understanding how specificity generated within the framework of pleiotropic signaling is a major challenge. A thorough understanding of this would be instrumental in designing pathway specific inhibitors of NFkappaB for the treatment of specific human ailments.
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Affiliation(s)
- Vinay Tergaonkar
- Institute for Molecular and Cell Biology, 61 Proteos, Biopolis Drive, Singapore 138673, Singapore.
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36
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Moussian B, Roth S. Dorsoventral axis formation in the Drosophila embryo--shaping and transducing a morphogen gradient. Curr Biol 2006; 15:R887-99. [PMID: 16271864 DOI: 10.1016/j.cub.2005.10.026] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The graded nuclear location of the transcription factor Dorsal along the dorsoventral axis of the early Drosophila embryo provides positional information for the determination of different cell fates. Nuclear uptake of Dorsal depends on a complex signalling pathway comprising two parts: an extracellular proteolytic cascade transmits the dorsoventral polarity of the egg chamber to the early embryo and generates a gradient of active Spätzle protein, the ligand of the receptor Toll; an intracellular cascade downstream of Toll relays this graded signal to embryonic nuclei. The slope of the Dorsal gradient is not determined by diffusion of extracellular or intracellular components from a local source, but results from self-organised patterning, in which positive and negative feedback is essential to create and maintain the ratio of key factors at different levels, thereby establishing and stabilising the graded spatial information for Dorsal nuclear uptake.
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Affiliation(s)
- Bernard Moussian
- Department of Genetics, Max-Planck Institute for Developmental Biology, Spemannstr. 35, 72076 Tübingen, Germany
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37
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Wagstaff KM, Jans DA. Intramolecular masking of nuclear localization signals: analysis of importin binding using a novel AlphaScreen-based method. Anal Biochem 2005; 348:49-56. [PMID: 16300722 DOI: 10.1016/j.ab.2005.10.029] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 09/29/2005] [Accepted: 10/14/2005] [Indexed: 10/25/2022]
Abstract
Active nuclear import of proteins requires the recognition of a nuclear localization sequence (NLS) by members of the importin (IMP) family of proteins. We have developed a modified AlphaScreen-based assay able to estimate the solution binding affinities of such interactions using biotinylated IMPs and His6-tagged NLS-containing proteins. We describe this assay in detail as well as its application in documenting the phenomenon of intramolecular masking of NLSs using recombinant green fluorescent protein (GFP) fusion proteins containing sequences from the SV40 large tumor T antigen (T-ag). We also use it to examine, for the first time, IMP binding to the cancer cell-specific proapoptotic factor viral protein 3 (VP3) from the chicken anemia virus (CAV). High-affinity binding of the IMPalpha/beta heterodimer to the T-ag NLS was observed when the GFP tag was fused to its N terminus but not to its C terminus. Effects of flanking residues were also observed in GFP-T-ag fusion derivatives containing the Thr128 NLS-inactivating mutation, whereby the absence of flanking sequences N terminal to the T-ag NLS appeared to decrease the specificity of the mutation in terms of oblating IMPalpha/beta binding. IMPbeta, but not IMPalpha or the IMPalpha/beta heterodimer, was found to bind to CAV VP3 with high affinity. Interestingly, GFP-VP3(74-121) bound to IMPbeta with threefold higher affinity than the full-length protein, GFP-VP3(1-121), implying that the NLS is masked to a significant extent in the context of full-length protein. This may represent a regulatory mechanism to control nuclear import in a tumor cell-specific fashion.
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Affiliation(s)
- Kylie M Wagstaff
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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38
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Fagerlund R, Kinnunen L, Köhler M, Julkunen I, Melén K. NF-{kappa}B is transported into the nucleus by importin {alpha}3 and importin {alpha}4. J Biol Chem 2005; 280:15942-51. [PMID: 15677444 DOI: 10.1074/jbc.m500814200] [Citation(s) in RCA: 229] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NF-kappaB transcription factors are retained in the cytoplasm in an inactive form until they are activated and rapidly imported into the nucleus. We identified importin alpha3 and importin alpha4 as the main importin alpha isoforms mediating TNF-alpha-stimulated NF-kappaB p50/p65 heterodimer translocation into the nucleus. Importin alpha3 and alpha4 are close relatives in the human importin alpha family. We show that importin alpha3 isoform also mediates nuclear import of NF-kappaB p50 homodimer in nonstimulated cells. Importin alpha3 is shown to directly bind to previously characterized nuclear localization signals (NLSs) of NF-kappaB p50 and p65 proteins. Importin alpha molecules are known to have armadillo repeats that constitute the N-terminal and C-terminal NLS binding sites. We demonstrate by site-directed mutagenesis that NF-kappaB p50 binds to the N-terminal and p65 to the C-terminal NLS binding site of importin alpha3. In vitro competition experiments and analysis of cellular NF-kappaB suggest that NF-kappaB binds to importin alpha only when it is free of IkappaBalpha. The present study demonstrates that the nuclear import of NF-kappaB is a highly regulated process mediated by a subset of importin alpha molecules.
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Affiliation(s)
- Riku Fagerlund
- Departments of Viral Diseases and Immunology and Epidemiology and Health Promotion, National Public Health Institute, FIN-00300, Helsinki, Finland.
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39
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Abstract
Transport of macromolecules into and out of the nucleus is generally effected by targeting signals that are recognized by specific members of the importin/exportin transport receptor family. The latter mediate passage through the nuclear envelope-embedded nuclear pore complexes (NPCs) by conferring interaction with NPC constituents, as well as with other components of the nuclear transport machinery, including the guanine nucleotide-binding protein Ran. Importantly, nuclear transport is regulated at multiple levels via a diverse range of mechanisms, such as the modulation of the accessibility and affinity of target signal recognition by importins/exportins, with phosphorylation/dephosphorylation as a major mechanism. Alteration of the level of the expression of components of the nuclear transport machinery also appears to be a key determinant of transport efficiency, having central importance in development, differentiation and transformation.
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Affiliation(s)
- Ivan K H Poon
- Department for Biochemistry and Molecular Biology, Nuclear Signalling Laboratory, Box 13D, Monash University, Clayton, Victoria 3168, Australia
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40
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Beramendi A, Peron S, Megighian A, Reggiani C, Cantera R. The inhibitorκB-ortholog Cactus is necessary for normal neuromuscular function in Drosophila melanogaster. Neuroscience 2005; 134:397-406. [PMID: 15975723 DOI: 10.1016/j.neuroscience.2005.04.046] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 04/22/2005] [Accepted: 04/23/2005] [Indexed: 10/25/2022]
Abstract
The Drosophila inhibitor-kappaB ortholog Cactus acts as an inhibitor of the Rel-transcription factors Dorsal and Dif. In blastoderm cells and immune competent cells, Cactus inhibits Dorsal and Dif by preventing their nuclear localization. Cactus, Dorsal and Dif are also expressed in somatic muscles, where Cactus and Dorsal, but not Dif, are enriched at the neuromuscular junction. Mutations in dorsal cause neuromuscular defects and mislocalization of Cactus. Here, we investigated whether mutations in cactus affect the neuromuscular system and subcellular localization of Dorsal and Dif. Using locomotion assays, as well as physiological and immunochemical methods, we found that wild type Cactus is necessary for the normal function of the larval neuromuscular system. The phenotype comprises i) altered bouton numbers and impaired neurotransmitter release in the neuromuscular junctions in the abdominal segments, ii) muscular weakness and iii) poor locomotion performance, probably reflecting a general neuromuscular impairment. Interestingly, in cactus mutants the subcellular localization of Dorsal and Dif in muscle is not affected, whereas cactus protein is not detected in the nucleus. This suggests, together with the similarities between the phenotypes induced by cactus and dorsal mutations, that in larval muscles the function of Cactus might be cooperation to the transcriptional activity of Rel proteins more than their cytoplasmic retention. The similarities with inhibitor-kappaB/nuclear factor kappaB interactions and muscle pathology in mammals point to Drosophila as a suitable experimental system to clarify the complex interactions of these proteins in muscle postembryonic development and activity.
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Affiliation(s)
- A Beramendi
- Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden
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41
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Lopes ESS, Araujo HM. The maternal JAK/STAT pathway of Drosophila regulates embryonic dorsal-ventral patterning. Braz J Med Biol Res 2004; 37:1811-8. [PMID: 15558187 DOI: 10.1590/s0100-879x2004001200006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of NFkappaB plays a pivotal role in many cellular processes such as inflammation, proliferation and apoptosis. In Drosophila, nuclear translocation of the NFkappaB-related transcription factor Dorsal is spatially regulated in order to subdivide the embryo into three primary dorsal-ventral (DV) domains: the ventral presumptive mesoderm, the lateral neuroectoderm and the dorsal ectoderm. Ventral activation of the Toll receptor induces degradation of the IkappaB-related inhibitor Cactus, liberating Dorsal for nuclear translocation. In addition, other pathways have been suggested to regulate Dorsal. Signaling through the maternal BMP member Decapentaplegic (Dpp) inhibits Dorsal translocation along a pathway parallel to and independent of Toll. In the present study, we show for the first time that the maternal JAK/STAT pathway also regulates embryonic DV patterning. Null alleles of loci coding for elements of the JAK/STAT pathway, hopscotch (hop), marelle (mrl) and zimp (zimp), modify zygotic expression along the DV axis. Genetic analysis suggests that the JAK kinase Hop, most similar to vertebrate JAK2, may modify signals downstream of Dpp. In addition, an activated form of Hop results in increased levels of Cactus and Dorsal proteins, modifying the Dorsal/Cactus ratio and consequently DV patterning. These results indicate that different maternal signals mediated by the Toll, BMP and JAK/STAT pathways may converge to regulate NFkappaB activity in Drosophila.
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Affiliation(s)
- E S S Lopes
- Departamento de Histologia e Embriologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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42
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Foley E, O'Farrell PH. Functional dissection of an innate immune response by a genome-wide RNAi screen. PLoS Biol 2004; 2:E203. [PMID: 15221030 PMCID: PMC434151 DOI: 10.1371/journal.pbio.0020203] [Citation(s) in RCA: 187] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Accepted: 05/04/2004] [Indexed: 12/18/2022] Open
Abstract
The innate immune system is ancient and highly conserved. It is the first line of defense and the only recognizable immune system in the vast majority of metazoans. Signaling events that convert pathogen detection into a defense response are central to innate immunity. Drosophila has emerged as an invaluable model organism for studying this regulation. Activation of the NF-kappaB family member Relish by the caspase-8 homolog Dredd is a central, but still poorly understood, signaling module in the response to gram-negative bacteria. To identify the genes contributing to this regulation, we produced double-stranded RNAs corresponding to the conserved genes in the Drosophila genome and used this resource in genome-wide RNA interference screens. We identified numerous inhibitors and activators of immune reporters in a cell culture model. Epistatic interactions and phenotypes defined a hierarchy of gene action and demonstrated that the conserved gene sickie is required for activation of Relish. We also showed that a second gene, defense repressor 1, encodes a product with characteristics of an inhibitor of apoptosis protein that inhibits the Dredd caspase to maintain quiescence of the signaling pathway. Molecular analysis revealed that Defense repressor 1 is upregulated by Dredd in a feedback loop. We propose that interruption of this feedback loop contributes to signal transduction.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Western
- Caspase 8
- Caspases/metabolism
- Cell Line
- Drosophila
- Drosophila Proteins/metabolism
- Epistasis, Genetic
- Gene Expression Regulation
- Gene Library
- Genes, Reporter
- Genome
- Image Processing, Computer-Assisted
- Immunity, Innate
- Insect Proteins/metabolism
- Microscopy, Fluorescence
- Models, Biological
- Models, Genetic
- Molecular Sequence Data
- NF-kappa B/metabolism
- Phenotype
- RNA Interference
- RNA, Double-Stranded/metabolism
- Sequence Homology, Amino Acid
- Signal Transduction
- Transcription Factors/metabolism
- Up-Regulation
- beta-Galactosidase/metabolism
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Affiliation(s)
- Edan Foley
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
| | - Patrick H O'Farrell
- 1Department of Biochemistry and Biophysics, University of California, San FranciscoSan Francisco, CaliforniaUnited States of America
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43
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Abstract
Drosophila mounts a potent host defence when challenged by various microorganisms. Analysis of this defence by molecular genetics has now provided a global picture of the mechanisms by which this insect senses infection, discriminates between various classes of microorganisms and induces the production of effector molecules, among which antimicrobial peptides are prominent. An unexpected result of these studies was the discovery that most of the genes involved in the Drosophila host defence are homologous or very similar to genes implicated in mammalian innate immune defences. Recent progress in research on Drosophila immune defence provides evidence for similarities and differences between Drosophila immune responses and mammalian innate immunity.
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Affiliation(s)
- Jules A Hoffmann
- Institut de Biologie Moléculaire et Cellulaire du CNRS, 67084 Strasbourg Cedex, France.
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44
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Hou S, Guan H, Ricciardi RP. Phosphorylation of serine 337 of NF-kappaB p50 is critical for DNA binding. J Biol Chem 2003; 278:45994-8. [PMID: 12947093 DOI: 10.1074/jbc.m307971200] [Citation(s) in RCA: 74] [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
It has been demonstrated that phosphorylation of the p50 subunit of NF-kappaB is required for efficient DNA binding, yet the specific phospho-residues of p50 have not been determined. In this study, we substituted all of the serine and conserved threonine residues in the p50 Rel homology domain and identified three serine residues, Ser65, Ser337, and Ser342, as critical for DNA binding without affecting dimerization. Although substitution with negatively charged aspartic acid at each of these positions failed to restore DNA binding, substitution with threonine, a potential phospho-acceptor, retained DNA binding for residues 65 and 337. In particular, Ser337, in a consensus site for protein kinase A (PKA) and other kinases, was shown to be phosphorylated both in vitro and in vivo. Importantly, phosphorylation of Ser337 by PKA in vitro dramatically increased DNA binding of p50. This study shows for the first time that the DNA binding ability of NF-kappaB p50 subunit is regulated through phosphorylation of residue Ser337, which has implications for both positive and negative control of NF-kappaB transcription.
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Affiliation(s)
- Shihe Hou
- Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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45
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Maier HJ, Marienfeld R, Wirth T, Baumann B. Critical role of RelB serine 368 for dimerization and p100 stabilization. J Biol Chem 2003; 278:39242-50. [PMID: 12874295 DOI: 10.1074/jbc.m301521200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In mature B cells RelB-containing complexes are constitutively present in the nucleus, and they are less susceptible to inhibitory kappaB proteins. In most other cell types inhibitory kappaB proteins prevent nuclear translocation and activation of NFkappaB. We reasoned that this characteristic might be because of post-translational modifications of RelB. In Drosophila, signal-dependent phosphorylation of the Rel homologue Dorsal at serine 317 has been shown to be critical for nuclear import. The evolutionary conservation of this serine prompted us to analyze the function of the corresponding site in RelB. As a model system we used the murine S107 plasmacytoma cell line, which lacks endogenous RelB expression. Analysis of S107 cells expressing wild type RelB and serine 368 mutants reveals that serine 368 is not required for nuclear import but that it is critical for RelB dimerization with other members of the NFkappaB family. Similar effects were obtained when the conserved serine in RelA was mutated. We further demonstrate that expression of functional RelB, but not of serine 368 mutants, severely reduces p52 generation and strongly increases expression of the p52 precursor, p100. Wild type RelB, but not mutant RelB, prolonged p100 half-life. We therefore suggest an inhibitory effect of RelB on p100 processing, which is possibly regulated in a signal-dependent manner.
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Affiliation(s)
- Harald Jakob Maier
- Department of Physiological Chemistry, Ulm University, Ulm 89081, Germany
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46
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Nicoll JB, Gwinn BL, Iwig JS, Garcia PP, Bunn CF, Allison LA. Compartment-specific phosphorylation of rat thyroid hormone receptor alpha1 regulates nuclear localization and retention. Mol Cell Endocrinol 2003; 205:65-77. [PMID: 12890568 DOI: 10.1016/s0303-7207(03)00199-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The thyroid hormone receptor alpha1 (TRalpha1) is a transcription factor, which can activate or repress gene expression in response to thyroid hormone. In addition, some of its actions, including DNA binding and transcriptional activation, are thought to be regulated by phosphorylation. Results presented here, using Xenopus oocyte microinjection assays, demonstrate that a phosphorylated form of rat TRalpha1 is present in the nucleus, whereas unphosphorylated TRalpha1 remains cytoplasmic. Changes in the phosphorylation state of TRalpha1 occur rapidly and point to the possibility that phosphorylation occurs in the nucleus. Furthermore, increasing the overall phosphorylation state of the cell leads to enhanced nuclear retention of TRalpha1, suggesting that compartment-specific phosphorylation regulates nuclear localization of TRalpha1. Enhanced nuclear retention of TRalpha1 is not dependent on phosphorylation of serine 12, a well-characterized casein kinase II site, nor is phosphorylation of this site necessary for import of TRalpha1 into the Xenopus oocyte nucleus. Similarly, mutational analysis in mammalian cells shows that nuclear localization and partitioning of TRalpha1 to the nuclear matrix are independent of serine 12 phosphorylation. Taken together, these studies suggest that phosphorylation of one or more sites in TRalpha1, excluding serine 12, enhances nuclear retention and/or inhibits nuclear export but is not directly involved in nuclear import.
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Affiliation(s)
- James B Nicoll
- Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, VA 23187, USA
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Abstract
BACKGROUND The NF-kappaB/Rel pathway functions in the establishment of dorsal-ventral polarity and in the innate humoral and cellular immune response in Drosophila. An important aspect of all NF-kappaB/Rel pathways is the translocation of the Rel proteins from the cytoplasm to the nucleus, where they function as transcription factors. RESULTS We have identified a new protein, Tamo, which binds to Drosophila Rel protein Dorsal, but not to Dorsal lacking the nuclear localization sequence. Tamo does not bind to the other Drosophila Rel proteins, Dif and Relish. The Tamo-Dorsal complex forms in the cytoplasm and Tamo also interacts with a cytoplasmically orientated nucleoporin. In addition Tamo binds the Ras family small GTPase, Ran. Tamo functions during oogenesis and, based on phenotypic analysis, controls the levels of nuclear Dorsal in early embryos. It further regulates the accumulation of Dorsal in the nucleus after immune challenge. CONCLUSIONS Tamo has an essential function during oogenesis. Tamo interacts with Dorsal and proteins that are part of the nuclear import machinery. We propose that tamo modulates the levels of import of Dorsal and other proteins.
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Affiliation(s)
- Svetlana Minakhina
- Waksman Institute, Department of Molecular Biology and Biochemistry, NJ Cancer Center, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854-8020, USA
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Vanden Berghe W, De Bosscher K, Vermeulen L, De Wilde G, Haegeman G. Induction and repression of NF-kappa B-driven inflammatory genes. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2003:233-78. [PMID: 12355719 DOI: 10.1007/978-3-662-04660-9_14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- W Vanden Berghe
- Unit of Eukaryotic Gene Expression and Signal Transduction, Department of Molecular Biology, University of Gent-VIB, K.L. Ledeganckstraat 35, 9000 Gent, Belgium.
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Bolatto C, Chifflet S, Megighian A, Cantera R. Synaptic activity modifies the levels of Dorsal and Cactus at the neuromuscular junction of Drosophila. JOURNAL OF NEUROBIOLOGY 2003; 54:525-36. [PMID: 12532402 DOI: 10.1002/neu.10179] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Drosophila Rel transcription factor Dorsal and its inhibitor Cactus participate in a signal transduction pathway involved in several biologic processes, including embryonic pattern formation, immunity, and muscle development. In contrast with embryonic muscle, where Dorsal is reportedly absent, this protein and Cactus accumulates in the neuromuscular junctions in the muscle of both larvae and adults. The phenotype of homozygous dorsal mutant larvae suggested that Dorsal and Cactus maybe necessary for normal function and maintenance of the neuromuscular system. Here we investigate if these proteins can respond to synaptic activity. Using larval body wall preparations and antibodies specific for Dorsal or Cactus we show that the amount of these proteins at the neuromuscular junction is substantially decreased after electrical stimulation of the nerves or incubation in glutamate, the principal transmitter in this type of synapse. The specificity of the response was tested with a glutamate receptor antagonist (argiotoxin 636). Because the effect can be reproduced using a calcium ionophore (ionomycin treatment) as well as blocked by the inhibition of the muscle ryanodine receptor (tetracaine treatment), the involvement of calcium in this process seems likely. We also observed that the inhibition of the calcium dependent protein phosphatase calcineurin prevents the effect of glutamate on the fluorescence for Dorsal and Cactus, suggesting its participation in a signal transduction cascade that may activate Dorsal in the muscle independently of Toll. Our results are consistent with a novel function of the Rel factor Dorsal in a molecular pathway turned on by neural activity and/or contractile activity.
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Affiliation(s)
- Carmen Bolatto
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Uruguay
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Takano H, Gusella JF. The predominantly HEAT-like motif structure of huntingtin and its association and coincident nuclear entry with dorsal, an NF-kB/Rel/dorsal family transcription factor. BMC Neurosci 2002; 3:15. [PMID: 12379151 PMCID: PMC137586 DOI: 10.1186/1471-2202-3-15] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2002] [Accepted: 10/14/2002] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Huntington's disease (HD) pathogenesis is due to an expanded polyglutamine tract in huntingtin, but the specificity of neuronal loss compared with other polyglutamine disorders also implies a role for the protein's unknown inherent function. Huntingtin is moderately conserved, with 10 HEAT repeats reported in its amino-terminal half. HD orthologues are evident in vertebrates and Drosophila, but not in Saccharomyces cerevisiae, Caenorhabditis elegans or Arabidopsis thaliana, a phylogenetic profile similar to the NF-kB/Rel/dorsal family transcription factors, suggesting a potential functional relationship. RESULTS We initially tested the potential for a relationship between huntingtin and dorsal by overexpression experiments in Drosophila S2 cells. Drosophila huntingtin complexes via its carboxyl-terminal region with dorsal, and the two enter the nucleus concomitantly, partly in a lipopolysaccharide (LPS)- and Nup88-dependent manner. Similarly, in HeLa cell extracts, human huntingtin co-immunoprecipitates with NF-kB p50 but not with p105. By cross-species comparative analysis, we find that the carboxyl-terminal segment of huntingtin that mediates the association with dorsal possesses numerous HEAT-like sequences related to those in the amino-terminal segment. Thus, Drosophila and vertebrate huntingtins are composed predominantly of 28 to 36 degenerate HEAT-like repeats that span the entire protein. CONCLUSION Like other HEAT-repeat filled proteins, huntingtin is made up largely of degenerate HEAT-like sequences, suggesting that it may play a scaffolding role in the formation of particular protein-protein complexes. While many proteins have been implicated in complexes with the amino-terminal region of huntingtin, the NF-kB/Rel/dorsal family transcription factors merit further examination as direct or indirect interactors with huntingtin's carboxyl-terminal segment.
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Affiliation(s)
- Hiroki Takano
- Molecular Neurogenetics Unit, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, MGH-East Building 149, 13 Street, Charlestown, Massachusetts 02129
| | - James F Gusella
- Molecular Neurogenetics Unit, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, MGH-East Building 149, 13 Street, Charlestown, Massachusetts 02129
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