| 1. |
- 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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| 2. |
- 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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