Publications (8)32.97 Total impact
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Dataset: Oliveira 2012 EJI supporting information
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Article: CD6 attenuates early and late signaling events, setting thresholds for T‐cell activation
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ABSTRACT: The T lineage glycoprotein CD6 is generally considered to be a costimulator of T-cell activation. Here, we demonstrate that CD6 significantly reduces early and late T-cell responses upon superantigen stimulation or TCR triggering by Abs. Measuring calcium mobilization in single cells responding to superantigen, we found that human T cells expressing rat CD6 react significantly less well compared with T cells not expressing the exogenous receptor. When the cytoplasmic domain of rat CD6 was removed, calcium responses were recovered, indicating that the inhibitory properties of CD6 are attributable to its cytoplasmic domain. Calcium responses, and also late indicators of T-cell activation such as IL-2 release, were also diminished in TCR-activated Jurkat cells expressing human CD6, compared with CD6-deficient cells or cells expressing a cytoplasmic deletion mutant of human CD6. Similarly, calcium signals triggered by anti-CD3 were enhanced in human T lymphocytes following morpholino-mediated suppression of CD6 expression. Finally, the proliferation of T lymphocytes was increased when the CD6–CD166 interaction was blocked with anti-CD166 Abs, but inhibited when anti-CD6 Abs were used. Our data suggest that CD6 is a signaling attenuator whose expression alone, i.e. in the absence of ligand engagement, is sufficient to restrain signaling in T cells.European Journal of Immunology 11/2011; 42(1):195 - 205. · 5.10 Impact Factor -
Article: Protein interactions between CD2 and Lck are required for the lipid raft distribution of CD2.
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ABSTRACT: In T lymphocytes, lipid rafts are preferred sites for signal transduction initiation and amplification. Many cell membrane receptors, such as the TCR, coreceptors, and accessory molecules associate within these microdomains upon cell activation. However, it is still unclear in most cases whether these receptors interact with rafts through lipid-based amino acid modifications or whether raft insertion is driven by protein-protein interactions. In murine T cells, a significant fraction of CD2 associates with membrane lipid rafts. We have addressed the mechanisms that control the localization of rat CD2 at the plasma membrane, and its redistribution within lipid rafts induced upon activation. Following incubation of rat CD2-expressing cells with radioactive-labeled palmitic acid, or using CD2 mutants with Cys226 and Cys228 replaced by alanine residues, we found no evidence that rat CD2 was subjected to lipid modifications that could favor the translocation to lipid rafts, discarding palmitoylation as the principal mechanism for raft addressing. In contrast, using Jurkat cells expressing different CD2 and Lck mutants, we show that the association of CD2 with the rafts fully correlates with CD2 capacity to bind to Lck. As CD2 physically interacts with both Lck and Fyn, preferentially inside lipid rafts, and reflecting the increase of CD2 in lipid rafts following activation, CD2 can mediate the interaction between the two kinases and the consequent boost in kinase activity in lipid rafts.The Journal of Immunology 02/2008; 180(2):988-97. · 5.79 Impact Factor -
Article: Extracellular isoforms of CD6 generated by alternative splicing regulate targeting of CD6 to the immunological synapse.
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ABSTRACT: The great majority of mammalian genes yield multiple transcripts arising from differential mRNA processing, but in very few instances have alternative forms been assigned distinct functional properties. We have cloned and characterized a new isoform of the accessory molecule CD6 that lacks the CD166 binding domain and is expressed in rat and human primary cells. The novel isoform, CD6Deltad3, results from exon 5 skipping and consequently lacks the third scavenger receptor cysteine-rich (SRCR) domain of CD6. Differential expression of the SRCR domain 3 resulted in a remarkable functional difference: whereas full-length CD6 targeted to the immunological synapse, CD6Deltad3 was unable to localize at the T cell:APC interface during Ag presentation. Analysis of expression of CD6 variants showed that, while being more frequent in coexpression with full-length CD6, the CD6Deltad3 isoform constituted the sole species in a small percentage of T cells. In the rat thymus, CD6Deltad3 is less represented in double-positive thymocytes but is detectable in nearly 50% of single-positive CD4 or CD8 thymocytes, suggesting that CD6 switching between full-length and Deltad3 isoforms may be involved in thymic selection. Strikingly, CD6Deltad3 is markedly up-regulated upon activation of T lymphocytes, partially substituting full-length CD6, as evaluated by RT-PCR analysis at the single-cell level, by immunoblotting, and by flow cytometry using Abs recognizing SRCR domains 1 and 3 of human CD6. This elegant mechanism controlling the expression of the CD166 binding domain may help regulate signaling delivered by CD6, through different types of extracellular engagement.The Journal of Immunology 05/2007; 178(7):4351-61. · 5.79 Impact Factor -
Article: Protein crosstalk in lipid rafts.
Advances in experimental medicine and biology 02/2006; 584:127-36. · 1.09 Impact Factor -
Article: OX52 is the rat homologue of CD6: evidence for an effector function in the regulation of CD5 phosphorylation.
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ABSTRACT: The MRC OX52 monoclonal antibody is a marker of rat T lymphocytes. We have cloned by polymerase chain reaction the rat homologue of CD6, and fluorescein-activated cell sorter analysis and immunoprecipitations using OX52 in COS7 cells transfected with rat CD6 cDNA showed that CD6 is the cell-surface molecule recognized by OX52. Immunoprecipitation analysis showed that CD6 coprecipitated with CD5, which in turn, was coprecipitated equivalently with CD2, CD6, and the T cell receptor (TCR), but the fraction of CD5 associated with CD6 was highly phosphorylated in kinase assays, in marked contrast with the low level of phosphorylation of CD5 associated with TCR or CD2. Examination of protein kinases associating with these antigens showed that paradoxically, CD2 coprecipitated the highest amount of Lck and Fyn. CD6 also associated with Lck, Fyn, and ZAP-70, although at lower levels but additionally coprecipitated the Tec family kinase Itk, which is absent from CD2, CD5, and TCR complexes. Lck together with Itk was the best combination of kinases, effectively phosphorylating synthetic peptides corresponding to a cytoplasmic sequence of CD5. Overall, our results suggest that CD6 has an important role in the regulation of CD5 tyrosine phosphorylation, probably as a result of its unique feature of associating with kinases of different families.Journal of Leukocyte Biology 02/2003; 73(1):183-90. · 4.99 Impact Factor -
Article: CD2 physically associates with CD5 in rat T lymphocytes with the involvement of both extracellular and intracellular domains.
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ABSTRACT: T lymphocytes can be activated and induced to proliferate through stimulation of the CD2 glycoprotein with functional combinations of CD2 antibodies. However, this mechanism of signal transduction via CD2 is still not fully understood. We have investigated which molecules on the T cell surface preferentially associate in Cis with CD2 and may regulate its signaling properties. Though a quantification method we found that CD5 represents the antigen capable of co-precipitating a larger proportion of CD2. Using co-capping assays and immunoprecipitations from cell lysates, we show that an association between CD2 and CD5 can be found in rat thymocytes, T lymphocytes and in a thymoma cell line. Possibly, this interaction is a direct one, since CD2 and CD5 transiently expressed in Cos7 cells co-precipitate each other. Furthermore, using CD2 chimeric proteins containing different domains of CD2, expressed in Cos7 cells as well as in stably transfected Jurkat cells, we show that the interaction between CD2 and CD5 is held at both the intra- and extracellular levels, but does not involve the transmembrane domain. The fact that both the extracellular and the cytoplasmic domains of CD2 interact with CD5 suggests a specific and tight association between the two molecules, possibly relevant for the fine-tuning of signal transduction in T lymphocytes.European Journal of Immunology 06/2002; 32(5):1509-18. · 5.10 Impact Factor -
Article: CD2 physically associates with CD5 in rat T lymphocytes with the involvement of both extracellular and intracellular domains
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ABSTRACT: T lymphocytes can be activated and induced to proliferate through stimulation of the CD2 glycoprotein with functional combinations of CD2 antibodies. However, this mechanism of signal transduction via CD2 is still not fully understood. We have investigated which molecules on the T cell surface preferentially associate in Cis with CD2 and may regulate its signaling properties. Though a quantification method we found that CD5 represents the antigen capable of co-precipitating a larger proportion of CD2. Using co-capping assays and immunoprecipitations from cell lysates, we show that an association between CD2 and CD5 can be found in rat thymocytes, T lymphocytes and in a thymoma cell line. Possibly, this interaction is a direct one, since CD2 and CD5 transiently expressed in Cos7 cells co-precipitate each other. Furthermore, using CD2 chimeric proteins containing different domains of CD2, expressed in Cos7 cells as well as in stably transfected Jurkat cells, we show that the interaction between CD2 and CD5 is held at both the intra- and extracellular levels, but does not involve the transmembrane domain. The fact that both the extracellular and the cytoplasmic domains of CD2 interact with CD5 suggests a specific and tight association between the two molecules, possibly relevant for the fine-tuning of signal transduction in T lymphocytes.European Journal of Immunology 04/2002; 32(5):1509 - 1518. · 5.10 Impact Factor
Top co-authors
Top Journals
Institutions
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2011
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French National Centre for Scientific Research
Lyon, Rhone-Alpes, France
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2002–2011
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Instituto de Biologia Molecular e Celular
Porto, Distrito do Porto, Portugal
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2007–2008
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University of Porto
- Instituto de Biologia Molecular e Celular (IBMC)
Porto, Distrito do Porto, Portugal
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