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- Amano, Mariane T, et al.
(författare)
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Genetic analysis of complement C1s deficiency associated with systemic lupus erythernatosus highlights alternative splicing of normal C1s gene
- 2008
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 45:6, s. 1693-1702
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Tidskriftsartikel (refereegranskat)abstract
- Deficiencies of complement proteins of the classical pathway are strongly associated with the development of autoimmune diseases. Deficiency of Clr has been observed to occur concomitantly with deficiency in Cls and 9 out of 15 reported cases presented systemic lupus erythernatosus (SLE). Here, we describe a family in which all four children are deficient in Cls but only two of them developed SLE. Hemolytic activity mediated by the alternative and the lectin pathways were normal, but classical pathway activation was absent in all children's sera. Cls was undetectable, while in the parents' sera it was lower than in the normal controls. The levels of Clr observed in the siblings and parents sera were lower than in the control, while the concentrations of other complement proteins (C3, C4, MBL and MASP-2) were normal in all family members. Impairment of Cls synthesis was observed in the patients' fibroblasts when analyzed by confocal microscopy. We show that all four siblings are homozygous for a mutation at position 938 in exon 6 of the Cls cDNA that creates a premature stop codon. Our investigations led us to reveal the presence of previously uncharacterized splice variants of Cls mRNA transcripts in normal human cells. These variants are derived from the skipping of exon 3 and from the use of an alternative 3' splice site within intron I which increases the size of exon 2 by 87 nucleotides.
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| 3. |
- Moller-Kristensen, Mette, et al.
(författare)
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Cooperation between MASP-1 and MASP-2 in the generation of C3 convertase through the MBL pathway
- 2007
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Ingår i: International Immunology. - : Oxford University Press (OUP). - 1460-2377 .- 0953-8178. ; 19:2, s. 141-149
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Tidskriftsartikel (refereegranskat)abstract
- The complement system is an important part of the innate immune system. Three pathways, the classical, the alternative and the lectin pathway, lead to the cleavage of complement factor C3, a central event in the activation of the complement system. We investigated the deposition of C3b (solid-phase C3 activation product) on a mannan-coated surface at high concentration of human serum (17%). At these conditions, mannan-binding lectin (MBL) promoted the activation of C3 through the combined action of MBL-associated serine protease (MASP)-1 and MASP-2 without appreciable involvement of the alternative pathway. In serum depleted of MASP-1, MASP-2 and MASP-3, we observed synergetic effect of reconstitution with MASP-1 and MASP-2. This was inhibited by MASP-3. No C3b deposition was observed with C2- or C4-depleted serum. Depletion of factor B had no effect on the MBL-MASP-promoted C3b deposition. Our results demonstrate a function of the orphan protease MASP-1 by providing evidence that this enzyme collaborates with MASP-2 in the generation of C3 convertase, a process observable at high serum concentration, but not at low serum concentration.
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