| 1. |
- Alonso, A, et al.
(författare)
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VHY, a novel myristoylated testis-restricted dual specificity protein phosphatase related to VHX
- 2004
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 279:31, s. 32586-32591
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Tidskriftsartikel (refereegranskat)abstract
- The human DUSP15 gene encodes an uncharacterized 235-amino acid member of the subfamily of small dual specificity protein phosphatases related to the Vaccinia virus VH1 phosphatase. Similar to VHR-related MKPX (VHX) (DUSP22), the predicted protein has an N-terminal myristoylation recognition sequence, and we show here that both are indeed modified by the attachment of a myristate to Gly-2. In recognition of this relatedness to VHX, we refer to the DUSP15-encoded protein as VH1-related member Y (VHY). We report that VHY is expressed at high levels in the testis and barely detectable levels in the brain, spinal cord, and thyroid. A VHY-specific antiserum detected a protein with an apparent molecular mass of 26 kDa, and histochemical analysis showed that VHY was readily detectable in pachytene spermatocytes (midstage of meiotic division I) and round spermatids and weakly in Leydig cells ( somatic cells outside of the seminiferous tubules). When expressed in 293T or NIH-3T3 cells, VHY was concentrated at the plasma membrane with some staining of vesicular structures in the Golgi region. Mutation of the myristoylation site Gly-2 abrogated membrane location. Finally, we demonstrate that VHY is an active phosphatase in vitro. We conclude that VHY is a new member of a subgroup of myristoylated VH1-like small dual specificity phosphatases.
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| 2. |
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| 3. |
- Gjörloff Wingren, Anette, et al.
(författare)
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The novel IgD binding protein from Moraxella catarrhalis induces human B lymphocyte activation and Ig secretion in the presence of Th2 cytokines.
- 2002
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Ingår i: Journal of Immunology. - 1550-6606. ; 168:11, s. 5582-5588
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella IgD binding protein (MID) is a novel bacterial outer membrane protein with IgD-binding properties. MID was purified from the respiratory pathogen Moraxella catarrhalis and is here shown to have B cell stimulatory properties. Purified MID in the range of 0.01-0.1 microg/ml was optimal to induce a proliferative response in human PBL. MID coupled to Sepharose and formalin-fixed M. catarrhalis preparations induced similar proliferative responses in PBL cultures. MID or MID-Sepharose stimulated purified human peripheral B cells as measured by proliferation. In contrast, MID or MID-Sepharose did not activate T cells. Preincubation of purified B cells with anti-IgD Abs inhibited MID-Sepharose-induced B cell proliferation. The addition of IL-4 specifically induced IL-6 production in MID-Sepharose-activated B cells. IgM secretion was detected in B cell cultures stimulated with MID or MID-Sepharose and IL-2 for 10 days. Secretion of IgG and IgA was efficiently induced in cultures from purified B cells stimulated with the combination of MID or MID-Sepharose and IL-4, IL-10, and soluble CD40 ligand, suggesting that Th2-derived cytokines were required for optimal plasma cell generation. Taken together, MID has properties that make it an important tool to study IgD-targeted activation of B cells.
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| 4. |
- Hadzic, Radinka
(författare)
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Activation of human B cells with the Moraxella catarrhalis IgD-binding protein MID
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Moraxella catarrhalis is a respiratory tract pathogen that causes significant health problems, including acute otitis media in children, lower respiratory tract infections in adults and the elderly and sinusitis in both children and adults. The interest in M. catarrhalis bacteria has increased over the past 20 years, both because of the emergence of the bacteria as a human pathogen and because of its increasing prevalence of antibiotic resistance. For these reasons, attention has been focused on the importance of a viable vaccine against M. catarrhalis. The outer membrane protein MID (Moraxella IgD-binding protein) from M. catarrhalis is one of the potential candidates. In this matter, knowledge of the interactions of potential candidates (i.e. MID) with human cells is of much significance. MID has the unique ability to bind to IgD-positive B lymphocytes (B cells). These cells are key agents in the immune system, with their specific role as immunoglobulin- (Ig) secreting cells. This ability is crucial for recognising and responding to external antigens, and is the underlying factor for adaptive immunity. In this thesis the interactions between MID and human B cells have been investigated. The potential of the MID protein to function as a B-cell activator has been studied using both primary B cells and different B cell lines. We show that MID has the capacity to activate peripheral blood and tonsillar B cells, to both proliferation and IL-6 secretion. The importance of B cell surface molecules for MID binding and activation of the cells has also been studied. Results presented here demonstrate that the two B cell co-receptors, CD19 and CD21, are highly important for MID-induced activation. We show that for a B-cell response in young individuals the CD19 molecule must be available. Furthermore, information from studies of different B cell lines indicates that the CD21 molecule is important in mediating a successful IgD-binding, although MID-binding to CD21 alone is not sufficient to induce cell activation. Moreover, we present data that MID-induced activation of tonsillar B cells is inhibited by Alpha-1-antitrypsin (AAT), a common serine inhibitor in plasma and tissues.
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| 5. |
- Hadzic, Radinka, et al.
(författare)
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alpha1-Antitrypsin inhibits Moraxella catarrhalis MID protein-induced tonsillar B cell proliferation and IL-6 release.
- 2006
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Ingår i: Immunology Letters. - : Elsevier BV. - 0165-2478 .- 1879-0542. ; 102:2, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- alpha 1-Antitrypsin (AAT) is a major circulating and tissues inhibitor of serine proteinases implicated in the regulation of inflammation and host defence. There is now increasing evidence that AAT may also exhibit anti-inflammatory activities independent of its protease inhibitor function. This study was undertaken to investigate the effects of native (inhibitory) and polymerized (non-inhibitory) forms of AAT on MID (Moraxella IgD binding protein)-induced human tonsillar B cell activation in vitro. We found that 0.5 mu g/ml MID induces B cell proliferation and stimulates IL-6 release (p < 0.001) relative to non-stimulated controls. Both native and polymerized AAT (0.5 mg/ml) inhibited MID-stimulated B cell proliferation in a similar manner (by 70%, p < 0.001), whereas MID-induced IL-6 release was more strongly suppressed by polymefized (9.9-fold, p < 0.001) as compared to native AAT (2.8-fold, p < 0.01). Electrophoretic analysis of cell culture media did not indicate any interaction between AAT and MID, and flow cytometry data showed no competition for the same receptor. The effects of AATs were observed whether added together with MID or 2 h after MID-addition to cell cultures. Thus, our data demonstrate that AAT inhibits MID-induced B cell activation in vitro that is unrelated to its protease inhibitory activity and is not dependent on MID binding to the cell surface.
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| 6. |
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| 7. |
- Hadzic, Radinka, et al.
(författare)
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α1-Antitrypsin inhibits Moraxella catarrhalis MID protein-induced tonsillar B cell proliferation and IL-6 release
- 2006
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Ingår i: Immunology Letters. - 0165-2478 .- 1879-0542. ; 102:2, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- α1-Antitrypsin (AAT) is a major circulating and tissues inhibitor of serine proteinases implicated in the regulation of inflammation and host defence. There is now increasing evidence that AAT may also exhibit anti-inflammatory activities independent of its protease inhibitor function. This study was undertaken to investigate the effects of native (inhibitory) and polymerized (non-inhibitory) forms of AAT on MID (Moraxella IgD binding protein)-induced human tonsillar B cell activation in vitro. We found that 0.5 μg/ml MID induces B cell proliferation and stimulates IL-6 release (p < 0.001) relative to non-stimulated controls. Both native and polymerized AAT (0.5 mg/ml) inhibited MID-stimulated B cell proliferation in a similar manner (by 70%, p < 0.001), whereas MID-induced IL-6 release was more strongly suppressed by polymerized (9.9-fold, p < 0.001) as compared to native AAT (2.8-fold, p < 0.01). Electrophoretic analysis of cell culture media did not indicate any interaction between AAT and MID, and flow cytometry data showed no competition for the same receptor. The effects of AATs were observed whether added together with MID or 2 h after MID-addition to cell cultures. Thus, our data demonstrate that AAT inhibits MID-induced B cell activation in vitro that is unrelated to its protease inhibitory activity and is not dependent on MID binding to the cell surface.
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