| 1. |
- Ge, Changrong P, et al.
(författare)
-
Anti-citrullinated protein antibodies cause arthritis by cross-reactivity to joint cartilage
- 2017
-
Ingår i: JCI INSIGHT. - : AMER SOC CLINICAL INVESTIGATION INC. - 2379-3708. ; 2:13
-
Tidskriftsartikel (refereegranskat)abstract
- Today, it is known that autoimmune diseases start a long time before clinical symptoms appear. Anti-citrullinated protein antibodies (ACPAs) appear many years before the clinical onset of rheumatoid arthritis (RA). However, it is still unclear if and how ACPAs are arthritogenic. To better understand the molecular basis of pathogenicity of ACPAs, we investigated autoantibodies reactive against the C1 epitope of collagen type II (CII) and its citrullinated variants. We found that these antibodies are commonly occurring in RA. A mAb (ACC1) against citrullinated C1 was found to cross-react with several noncitrullinated epitopes on native CII, causing proteoglycan depletion of cartilage and severe arthritis in mice. Structural studies by X-ray crystallography showed that such recognition is governed by a shared structural motif "RG-TG" within all the epitopes, including electrostatic potential-controlled citrulline specificity. Overall, we have demonstrated a molecular mechanism that explains how ACPAs trigger arthritis.
|
|
| 2. |
|
|
| 3. |
- Kihlberg, K., et al.
(författare)
-
Discrepancies between the one-stage clotting assay and the chromogenic assay in haemophilia B
- 2017
-
Ingår i: Haemophilia. - : Wiley. - 1351-8216. ; 23:4, s. 620-627
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Assay discrepancy in factor VIII activity between the one-stage and the chromogenic assays has been described in approximately one third of patients with non-severe haemophilia A. Whether assay discrepancy may also occur in patients with haemophilia B remains unknown. Aim: This study compared the results from the one-stage and the chromogenic assays in patients with haemophilia B. Methods: Plasma samples from patients with haemophilia B attending the haemophilia centre in Malmö, Sweden, were collected after a wash-out period of more than 7 days and analysed with both assays. Results: Fifty samples from 36 patients were analysed. No discrepancy was found in patients with severe haemophilia B. Among the 44 plasma samples from patients with non-severe disease, 15 showed a twofold or greater difference between the results of the two methods, with the chromogenic method presenting the higher value (mean FIX:Cone-stage 0.02 vs. FIX:Cchromo 0.06 IU mL-1). Of these 15 samples, 14 were from seven individuals from five families with the same mutated amino acid at the N-terminal cleaving site of the activation peptide (FIX: c.572G>A; p.Arg191His or FIX: c.571C>T; p.Arg191Cys). These mutations were not observed in any patients with non-discrepant results. The reported bleeding frequency for these patients was low and indicative of a mild bleeding phenotype. Conclusion: Our findings imply that assay discrepancy occurs for factor IX activity and that both type of assays are needed for a correct diagnosis and classification of haemophilia B. The underlying mechanism by which the mutation influences the assays remains to be determined.
|
|
| 4. |
|
|
| 5. |
- Vijayalekshmi, S., et al.
(författare)
-
A surface exposed O-linked galactose residue destabilises the structure of a folded helix-loop-helix dimer
- 2003
-
Ingår i: Organic and biomolecular chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 1, s. 2455-60
-
Tidskriftsartikel (refereegranskat)abstract
- A 42-residue glycopeptide Tn-15 and the corresponding reference polypeptide Thr-15 were designed and synthesized to provide a model system for the study of how glycosylation affects the stability of a molten globule-like protein. Tn-15 and Thr-15 fold into hairpin helix-loop-helix motifs that dimerise to form four-helix bundles and the only difference between the sequences is that Tn-15 carries an O-linked N-acetylgalactosamine residue at the side chain of threonine-15 whereas the sequence Thr-15 is unglycosylated. An analysis of the mean residue ellipticities at 222 nm of the two polypeptides and of the a-H chemical shift deviations from random coil values showed that glycosylation reduced the helical content of the polypeptides and increased the dissociation constant of the helix-loop-helix dimer to form monomers. The pH dependencies of the helical content of Tn-15 and Thr-15 differed as that of Thr-15 was largely unaffected by pH in the range from pH 4 to pH 10, whereas Tn-15 lost almost half of the helical content at pH 4 upon raising the pH to 10. No single amino acid residue was found to ionize in a way that could explain the observed pH dependence of Tn-15. The temperature dependence of the mean residue ellipticity of Tn-15 revealed a surprising decrease in helicity at 278 K in comparison with that at 293 K, reminiscent of cold denaturation, that was not observed for the reference four-helix bundle Thr-15.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- George, Shaji K, et al.
(författare)
-
Chemoenzymatic synthesis of derivatives of a T-cell-stimulating peptide which carry tumor-associated carbohydrate antigens
- 2001
-
Ingår i: Journal of the Chemical Society-Perkin Transactions 1. - : Royal Society of Chemistry (RSC). - 1472-7781 .- 1364-5463. ; , s. 880-5
-
Tidskriftsartikel (refereegranskat)abstract
- The Tn (GalNAc-Ser/Thr), T [Gal(13)GalNAc-Ser/Thr], sialyl-Tn [Neu5Ac(26)GalNAc-Ser/Thr] and 2,3-sialyl-T [Neu5Ac(23)Gal(13)GalNAc-Ser/Thr] antigens are examples of tumor-associated carbohydrate antigens expressed by epithelial cancers. We now describe the preparation of 2-bromoethyl glycosides corresponding to the Tn and T antigens in one and five chemical steps (51 and 15% total yield), respectively, starting from N-acetylgalactosamine. The 2-bromoethyl Tn and T glycosides were used to alkylate a homocysteine residue incorporated in a peptide that is able to bind to class I MHC molecules on antigen-presenting cells. The two neoglycopeptides were then converted into glycopeptides which carry the sialyl-Tn and 2,3-sialyl-T antigens by using recombinant sialyltransferases. Interestingly, the sialyltransferases were able to sialylate the Tn and T carbohydrate moieties even though they were linked to the peptide backbone via a spacer instead of being attached to serine or threonine. The four glycopeptides will be used in studies directed towards inducing a carbohydrate-specific T cell response against the Tn, T, sialyl-Tn, and 2,3-sialyl-T antigens.
|
|
| 9. |
- Geschwindner, Stefan, et al.
(författare)
-
Characterisation of de novo mutations in the C-terminal domain of proprotein convertase subtilisin/kexin type 9.
- 2015
-
Ingår i: Protein Engineering Design & Selection. - : Oxford University Press (OUP). - 1741-0126 .- 1741-0134.
-
Tidskriftsartikel (refereegranskat)abstract
- Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes the degradation of the hepatic low-density lipoprotein receptor (LDL-R) and is therefore a prominent therapeutic target for reducing LDL-cholesterol. The C-terminal domain of PCSK9 is unlikely to be involved in a direct extracellular interaction with the LDL-R. We probed the importance of the C-terminus for the degradation of the LDL-R by designing seven de novo mutants of PCSK9 that fill potential druggable cavities. The mutants were tested for their ability to diminish LDL uptake in human HepG2 cells and for affinity towards a calcium independent mutant of the EGF(A) domain of the human LDL-R. The later was done by a newly developed surface plasmon resonance-based assay format. We identified three mutant proteins (G517R, V610R and V644R) with decreased ability to block LDL uptake into HepG2 cells. These mutations define areas outside the direct interaction area between PCSK9 and the LDL-R that could be targeted to inhibit the PCSK9 triggered degradation of the LDL-R. We also describe the mechanistic rationalisation of the affinity changes seen with the natural occurring human D374Y (gain of function) mutation causing severe hypercholesterolaemia. The action of this mutant is due to a significantly decreased dissociation rate constant, whereas the mutation does not affect the association rate constant.
|
|
| 10. |
|
|
