| 1. |
- Salomonsson, Stina, et al.
(författare)
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Ro/SSA autoantibodies directly bind cardiomyocytes, disturb calcium homeostasis, and mediate congenital heart block
- 2005
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 201:1, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- Congenital heart block develops in fetuses after placental transfer of Ro/SSA autoantibodies from rheumatic mothers. The condition is often fatal and the majority of live-born children require a pacemaker at an early age. The specific antibody that induces the heart block and the mechanism by which it mediates the pathogenic effect have not been elucidated. In this study, we define the cellular mechanism leading to the disease and show that maternal autoantibodies directed to a specific epitope within the leucine zipper amino acid sequence 200–239 (p200) of the Ro52 protein correlate with prolongation of fetal atrioventricular (AV) time and heart block. This finding was further confirmed experimentally in that pups born to rats immunized with p200 peptide developed AV block. p200-specific autoantibodies cloned from patients bound cultured cardiomyocytes and severely affected Ca2+ oscillations, leading to accumulating levels and overload of intracellular Ca2+ levels with subsequent loss of contractility and ultimately apoptosis. These findings suggest that passive transfer of maternal p200 autoantibodies causes congenital heart block by dysregulating Ca2+ homeostasis and inducing death in affected cells.
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| 2. |
- Entesarian, Miriam, et al.
(författare)
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Mutations in the gene encoding fibroblast growth factor 10 are associated with
- 2005
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Ingår i: Nat Genet. - 1061-4036. ; 37:2, s. 125-7
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Tidskriftsartikel (refereegranskat)abstract
- Autosomal dominant aplasia of lacrimal and salivary glands (ALSG; OMIM 180920 and OMIM 103420) is a rare condition characterized by irritable eyes and dryness of the mouth. We mapped ALSG to 5p13.2-5q13.1, which coincides with the gene fibroblast growth factor 10 (FGF10). In two extended pedigrees, we identified heterozygous mutations in FGF10 in all individuals with ALSG. Fgf10(+/-) mice have a phenotype similar to ALSG, providing a model for this disorder. We suggest that haploinsufficiency for FGF10 during a crucial stage of development results in ALSG.
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| 3. |
- Entesarian, Miriam, et al.
(författare)
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Mutations in the gene encoding fibroblast growth factor 10 are associated with aplasia of lacrimal and salivary glands.
- 2005
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Ingår i: Nat Genet. ; 37:2, s. 125-7
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Tidskriftsartikel (refereegranskat)abstract
- Autosomal dominant aplasia of lacrimal and salivary glands (ALSG; OMIM 180920 and OMIM 103420) is a rare condition characterized by irritable eyes and dryness of the mouth. We mapped ALSG to 5p13.2-5q13.1, which coincides with the gene fibroblast growth factor 10 (FGF10). In two extended pedigrees, we identified heterozygous mutations in FGF10 in all individuals with ALSG. Fgf10(+/-) mice have a phenotype similar to ALSG, providing a model for this disorder. We suggest that haploinsufficiency for FGF10 during a crucial stage of development results in ALSG.
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| 4. |
- Espinosa, Alexander, et al.
(författare)
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Loss of the lupus autoantigen Ro52/Trim21 induces tissue inflammation and systemic autoimmunity by disregulating the IL-23-Th17 pathway
- 2009
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 206:8, s. 1661-1671
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Tidskriftsartikel (refereegranskat)abstract
- Ro52/Trim21 is targeted as an autoantigen in systemic lupus erythematosus and Sjögren's syndrome. Polymorphisms in the Ro52 gene have been linked to these autoimmune conditions, but the molecular mechanism by which Ro52 may promote development of systemic autoimmune diseases has not been explored. To address this issue, we generated Ro52-null mice (Ro52(-/-)), which appear phenotypically normal if left unmanipulated. However, Ro52(-/-) mice develop severe dermatitis extending from the site of tissue injury induced by ear tags. The affected mice further develop several signs of systemic lupus with hypergammaglobulinemia, autoantibodies to DNA, proteinuria, and kidney pathology. Ro52, which was recently identified as an E3 ligase, mediates ubiquitination of several members of the interferon regulatory factor (IRF) family, and the Ro52-deficient mice have an enhanced production of proinflammatory cytokines that are regulated by the IRF transcription factors, including cytokines involved in the Th17 pathway (interleukin [IL] 6, IL-12/IL-23p40, and IL-17). Loss of IL-23/IL-17 by genetic deletion of IL-23/p19 in the Ro52(-/-) mice conferred protection from skin disease and systemic autoimmunity. These data reveal that the lupus-associated Ro52 protein is an important negative regulator of proinflammatory cytokine production, and they provide a mechanism by which a defective Ro52 function can lead to tissue inflammation and systemic autoimmunity through the IL-23-Th17 pathway.
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| 5. |
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| 6. |
- Hennig, Janosch, et al.
(författare)
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The fellowship of the RING: The RING-B-box linker region (RBL) interacts with the RING in TRIM21/Ro52, contributes to an autoantigenic epitope in Sjögren's syndrome, and is an integral and conserved region in TRIM proteins
- 2008
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 377:2, s. 431-449
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Tidskriftsartikel (refereegranskat)abstract
- Ro52 is a major autoantigen that is targeted in the autoimmune disease Sjögren syndrome and belongs to the tripartite motif (TRIM) protein family. Disease-related antigenic epitopes are mainly found in the coiled-coil domain of Ro52, but one such epitope is located in the Zn2+-binding region, which comprises an N-terminal RING followed by a B-box, separated by a ∼40-residue linker peptide. In the present study, we extend the structural, biophysical, and immunological knowledge of this RING-B-box linker (RBL) by employing an array of methods. Our bioinformatic investigations show that the RBL sequence motif is unique to TRIM proteins and can be classified into three distinct subtypes. The RBL regions of all three subtypes are as conserved as their known flanking domains, and all are predicted to comprise an amphipathic helix. This helix formation is confirmed by circular dichroism spectroscopy and is dependent on the presence of the RING. Immunological studies show that the RBL is part of a conformation-dependent epitope, and its antigenicity is likewise dependent on a structured RING domain. Recombinant Ro52 RING-RBL exists as a monomer in vitro, and binding of two Zn2+ increases its stability. Regions stabilized by Zn2+ binding are identified by limited proteolysis and matrix-assisted laser desorption/ionization mass spectrometry. Furthermore, the residues of the RING and linker that interact with each other are identified by analysis of protection patterns, which, together with bioinformatic and biophysical data, enabled us to propose a structural model of the RING-RBL based on modeling and docking experiments. Sequence similarities and evolutionary sequence patterns suggest that the results obtained from Ro52 are extendable to the entire TRIM protein family.
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| 7. |
- Lövgren, Tanja, et al.
(författare)
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Induction of interferon-α by immune complexes or liposomes containing systemic lupus erythematosus autoantigen- and Sjögren's syndrome autoantigen-associated RNA
- 2006
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 54:6, s. 1917-1927
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Tidskriftsartikel (refereegranskat)abstract
- Objective To investigate the ability of systemic lupus erythematosus (SLE) autoantigen– and Sjögren's syndrome (SS) autoantigen–associated U1 small nuclear RNA (U1 snRNA) and hY1RNA to induce interferon-α (IFNα) production. Methods In vitro–transcribed U1 snRNA or hY1RNA and lipofectin were added to peripheral blood mononuclear cell (PBMC) cultures. Purified U1 snRNP particles and IgG from SLE patients (SLE-IgG) were added to cultures of PBMCs, enriched monocytes, or natural interferon–producing cells (NIPCs); the latter are also known as plasmacytoid dendritic cells (pDC). Cells were double-stained for IFNα and either blood dendritic cell antigen 2 (NIPCs/pDC) or CD14 (monocytes) and then analyzed by flow cytometry. In some experiments, RNase or inhibitors of Fcγ receptor IIa (FcγRIIa) (specific antibodies), endocytosis (chloroquine, bafilomycin A), or Toll-like receptors (TLRs; oligodeoxynucleotide 2088) were used. The produced IFNα was measured by immunoassay. Results Lipofected U1 snRNA and hY1RNA both induced IFNα production in monocytes, but not in NIPC/pDC. In contrast, U1 snRNP combined with SLE-IgG induced IFNα production only in NIPCs/pDC, and this response was decreased by RNase treatment or inhibition of the FcγRIIa, the endocytosis pathways, or the TLRs. Conclusion Our finding that U1 snRNA and hY1RNA have IFNα-inducing capacity indicates that immune complexes containing such RNA, for example U1 snRNP particles, can be at least partly responsible for the ongoing IFNα production seen in SLE and SS. These results may help to explain the molecular mechanisms behind the pathogenesis of these and other autoimmune diseases in which autoantibodies to RNA- binding proteins occur.
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| 8. |
- Ottosson, Lars, et al.
(författare)
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Structural, functional and immunologic characterization of folded subdomains in the Ro52 protein targeted in Sjögren's syndrome
- 2006
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 43:6, s. 588-598
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Tidskriftsartikel (refereegranskat)abstract
- Ro52, one of the major autoantigens in the rheumatic disease Sjögren's syndrome (SS), belongs to the tripartite motif (TRIM) or RING-B-box-coiled-coil (RBCC) protein family, thus comprising an N-terminal RING, followed by a B-box and a coiled-coil region. Several different proteomic functions have been suggested for Ro52, including DNA binding, protein interactions and Zn 2+-binding. To analyze the presence and/or absence of these functions and, in particular, map those to different subregions, the modular composition of the Ro52 protein was experimentally characterized. Two structured parts of Ro52 were identified, corresponding to the RING-B-box and the coiled-coil regions, respectively. Secondary structure analysis by circular dichroism (CD) spectroscopy indicated that the two subregions are independently structured. The entire RING-B-box region displayed Zn2+-dependent stabilization against proteolysis in the presence of Zn2+, indicating functional Zn2+-binding sites in both the RING and the B-box. However, no stabilization with DNA was detected, irrespective of Zn2+, thus suggesting that the RING-B-box region does not bind DNA. Oligomerization of the coiled-coil was investigated by analytical ultracentrifugation and in a mammalian two-hybrid system. Both methods show weak homodimer affinity, in parity with other coiled-coil domains involved in regulatory interactions. The C-terminal B30.2 region was rapidly degraded both during cellular expression and refolding, indicating a less stable structure. Immunologic analysis of the stable protein regions with sera from patients with Sjögren's syndrome shows that immunodominant epitopes to a large extent are localized in the structurally stable parts of Ro52. The results form a basis for further Ro52 functional studies on the proteome level. © 2005 Elsevier Ltd. All rights reserved.
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| 9. |
- Strandberg, Linn, et al.
(författare)
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Interferon-alpha induces up-regulation and nuclear translocation of the Ro52 autoantigen as detected by a panel of novel Ro52-specific monoclonal antibodies
- 2008
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Ingår i: Journal of Clinical Immunology. - : Springer Science and Business Media LLC. - 0271-9142 .- 1573-2592. ; 28:3, s. 220-31
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Tidskriftsartikel (refereegranskat)abstract
- Interferon-alpha (IFN-alpha) has been implicated in the pathogenesis of Sjögren's syndrome and systemic lupus erythematosus. Ro52, which was recently identified as an E3 ligase with anti-proliferative and pro-apoptotic properties, is a major autoantigen targeted in both these conditions. Microarray analyses have indicated up-regulation of Ro52 by IFN-alpha, and the objective of the present study was to address the potential link between IFN-alpha and Ro52. To investigate the influence of IFN-alpha on Ro52 protein levels and cellular localization, we generated a panel of monoclonal antibodies to different domains of Ro52. These novel monoclonal antibodies were characterized by immunoprecipitation, Western blot, and enzyme-linked immunosorbent assay using cell lysates, recombinant Ro52 protein, and synthetic peptides. Ro52 was up-regulated in HeLa cells and human B cells at the messenger RNA and protein levels in response to IFN-alpha stimulation as detected by reverse transcriptase polymerase chain reaction and Western blot. After up-regulation, Ro52 translocated from the cytoplasm to the nucleus. The nuclear translocation of Ro52 was observed after staining with generated monoclonal antibodies specific for both the RING, coiled-coil, and B30.2 domains of Ro52 and the nuclear translocation of Ro52 preceded IFN-alpha-induced apoptotic cell death detected by caspase-3 and TUNEL staining in the treated cultures. In conclusion, our data show that IFN-alpha first induces up-regulation of Ro52 protein and then prompts translocation of the up-regulated Ro52 protein in to the nucleus. The translocation precedes apoptosis of the IFN-alpha exposed cells, suggesting a role for Ro52 in mediating the anti-proliferative or pro-apoptotic effects of the autoimmune-related cytokine IFN-alpha.
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