| 1. |
- Borza, Corina M., et al.
(författare)
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Integrin alpha 3 beta 1, a Novel Receptor for alpha 3(IV) noncollagenous domain and a trans-dominant inhibitor for integrin alpha v beta 3
- 2006
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 281:30, s. 20932-20939
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Tidskriftsartikel (refereegranskat)abstract
- Exogenous soluble human alpha 3 noncollagenous (NC1) domain of collagen IV inhibits angiogenesis and tumor growth. These biological functions are attributed to the binding of alpha 3NC1 to integrin alpha v beta 3. However, in some tumor cells that express integrin alpha v beta 3, the alpha 3NC1 domain does not inhibit proliferation, suggesting that integrin alpha v beta 3 expression is not sufficient to mediate the anti-tumorigenic activity of this domain. Therefore, in the present study, we searched for novel binding receptors for the soluble alpha 3NC1 domain in cells lacking alpha v beta 3 integrin. In these cells, soluble alpha 3NC1 bound integrin alpha 3 beta 1; however, unlike alpha v beta 3, alpha 3 beta 1 integrin did not mediate cell adhesion to immobilized alpha 3NC1 domain. Interestingly, in cells lacking integrin alpha 3 beta 1, adhesion to the alpha 3NC1 domain was enhanced due to activation of integrin alpha v beta 3. These findings indicate that integrin alpha 3 beta 1 is a receptor for the alpha 3NC1 domain and transdominantly inhibits integrin alpha v beta 3 activation. Thus integrin alpha 3 beta 1, in conjunction with integrin alpha v beta 3, modulates cellular responses to the alpha 3NC1 domain, which may be pivotal in the mechanism underpinning its anti-angiogenic and anti-tumorigenic activities.
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| 2. |
- Chen, Lanlin, et al.
(författare)
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A nephritogenic peptide induces intermolecular epitope spreading on collagen IV in experimental autoimmune glomerulonephritis
- 2006
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 17:11, s. 3076-3081
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Tidskriftsartikel (refereegranskat)abstract
- This group previously identified a peptide p13 of alpha 3(IV)NC1 domain of type IV collagen that induces experimental autoimmune glomerulonephritis (EAG) in rats with generation of antibodies to sites on alpha 3(IV)NC1 external to the peptide as a result of intramolecular epitope spreading. It was hypothesized that intermolecular epitope spreading to other collagen IV chains also was induced. Rats were immunized with nephritogenic peptide that was derived from the amino terminal part of rat alpha 3(IV)NC1 domain, and serum and kidney eluate were examined for antibodies to both native and recombinant NC1 domains of collagen IV. Peptide induced EAG with proteinuria and decreased renal function and glomerular basement membrane IgG deposits. Sera from these rats were examined by ELISA, which revealed reactivity not only to immunizing peptide but also to human and rat alpha 3(IV)NC1 and to human alpha 4(IV)NC1 domains. Kidney eluate that was depleted of alpha 3(IV)NC1 antibodies still reacted to alpha 4(IV)NC1, and alpha 3(IV)NC1 column-bound antibody reacted with alpha 3(IV)NC1. There was minimal reactivity to other collagen chains. Eluate that was adsorbed to NC1 hexamer from rat glonterular basement membrane lost all reactivity to glomerular constituents, and the eluted antibodies reacted to alpha 3(IV)NC1 and alpha 4(IV)NC1 domains. These studies show that a T cell epitope of alpha 3(IV)NC1 induces EAG, intramolecular epitope spreading along alpha 3(IV)NC1, and intermolecular epitope spreading to alpha 4(IV)NC1 domain with minimal or no reactivity to other collagen chains or glomerular constituents. This is the first demonstration in EAG of intermolecular epitope spreading and identification of the spread epitopes.
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| 3. |
- Pedchenko, Vadim, et al.
(författare)
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Molecular Architecture of the Goodpasture Autoantigen in Anti-GBM Nephritis
- 2010
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Ingår i: New England Journal of Medicine. - 0028-4793. ; 363:4, s. 343-354
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND In Goodpasture's disease, circulating autoantibodies bind to the noncollagenous-1 (NC1) domain of type IV collagen in the glomerular basement membrane (GBM). The specificity and molecular architecture of epitopes of tissue-bound autoantibodies are unknown. Alport's post-transplantation nephritis, which is mediated by allo-antibodies against the GBM, occurs after kidney transplantation in some patients with Alport's syndrome. We compared the conformations of the antibody epitopes in Goodpasture's disease and Alport's post-transplantation nephritis with the intention of finding clues to the pathogenesis of anti-GBM glomerulonephritis. METHODS We used an enzyme-linked immunosorbent assay to determine the specificity of circulating autoantibodies and kidney-bound antibodies to NC1 domains. Circulating antibodies were analyzed in 57 patients with Goodpasture's disease, and kidney-bound antibodies were analyzed in 14 patients with Goodpasture's disease and 2 patients with Alport's post-transplantation nephritis. The molecular architecture of key epitope regions was deduced with the use of chimeric molecules and a three-dimensional model of the alpha 345NC1 hexamer. RESULTS In patients with Goodpasture's disease, both autoantibodies to the alpha 3NC1 monomer and antibodies to the alpha 5NC1 monomer (and fewer to the alpha 4NC1 monomer) were bound in the kidneys and lungs, indicating roles for the alpha 3NC1 and alpha 5NC1 monomers as autoantigens. High antibody titers at diagnosis of anti-GBM disease were associated with ultimate loss of renal function. The antibodies bound to distinct epitopes encompassing region Ea in the alpha 5NC1 monomer and regions E-A and Eb in the alpha 3NC1 monomer, but they did not bind to the native cross-linked alpha 345NC1 hexamer. In contrast, in patients with Alport's post-transplantation nephritis, allo-antibodies bound to the E-A region of the alpha 5NC1 subunit in the intact hexamer, and binding decreased on dissociation. CONCLUSIONS The development of Goodpasture's disease may be considered an autoimmune "conformeropathy" that involves perturbation of the quaternary structure of the alpha 345NC1 hexamer, inducing a pathogenic conformational change in the alpha 3NC1 and alpha 5NC1 subunits, which in turn elicits an autoimmune response.
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