The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Olli Silvennoinen - One of the best experts on this subject based on the ideXlab platform.
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transcriptional co activator Protein P100 interacts with snrnp Proteins and facilitates the assembly of the spliceosome
Nucleic Acids Research, 2007Co-Authors: Jie Yang, Tuuli Valineva, Jingxin Hong, Tianxu Bu, Ole Norregaard Jensen, Mikko J Frilander, Olli SilvennoinenAbstract:Transcription and pre-mRNA splicing are the key nuclear processes in eukaryotic gene expression, and identification of factors common to both processes has suggested that they are functionally coordinated. P100 Protein has been shown to function as a transcriptional co-activator for several transcription factors. P100 consists of staphylococcal nuclease (SN)-like and Tudor-SN (TSN) domains of which the SN-like domains have been shown to function in transcription, but the function of TSN domain has remained elusive. Here we identified interaction between P100 and small nuclear ribonucleoProteins (snRNP) that function in pre-mRNA splicing. The TSN domain of P100 specifically interacts with components of the U5 snRNP, but also with the other spliceosomal snRNPs. In vitro splicing assays revealed that the purified P100, and specifically the TSN domain of P100, accelerates the kinetics of the spliceosome assembly, particularly the formation of complex A, and the transition from complex A to B. Consistently, the P100 Protein, as well as the separated TSN domain, enhanced the kinetics of the first step of splicing in an in vitro splicing assay in dose-dependent manner. Thus our results suggest that P100 Protein is a novel dual function regulator of gene expression that participates via distinct domains in both transcription and splicing.
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Characterization of RNA helicase A as component of STAT6-dependent enhanceosome
Nucleic Acids Research, 2006Co-Authors: Tuuli Valineva, Jie Yang, Olli SilvennoinenAbstract:ABSTRACTSignal transducer and activator of transcription6 (STAT6) is a regulator of transcription forinterleukin-4 (IL-4)-induced genes. The ability ofSTAT6 to activate transcription depends on func-tional interaction with other transcription factorsand coactivators. We have characterized the mecha-nism of STAT6-mediated transcriptional activationby identifyingSTAT6 transcription activation domain(TAD) interacting nuclear Proteins. The first of theidentified Proteins was coactivator Protein P100,which regulates IL-4-induced transcription by con-necting STAT6 with other transcriptional regulators.Here, we describe RNA helicase A (RHA) as a novelcomponent of STAT6 transcriptosome. In vitro andin vivo experiments indicated that RHA did notdirectly interact with STAT6, but P100 Protein wasfound to mediate the assembly of the ternarycomplex of STAT6-P100-RHA. In chromatin immuno-precipitation studies RHA together with P100enhanced the binding of STAT6 on the human Ig « promoter after IL-4 stimulation. RHA enhanced theIL-4-induced transcription, and the participation ofRHA in IL-4-regulated transcription was supportedby RNAi experiments. Our results suggest that RHAhas an important role in the assembly of STAT6transcriptosome. As RHA is also known to interactwith chromatin modifying Proteins, the RHA con-taining Protein complexes may facilitate the entryof transcriptional apparatus to the IL-4 responsivepromoters.INTRODUCTIONRegulation of transcription is dependent both on generaltranscription factors as well as transcriptional activatorsand coactivators. These Proteins are assembled into a nucleo-Protein complex called the enhanceosome (1–3). In theenhanceosome transcriptional coactivators form multifunc-tional Protein–Protein complexes, which are assembled in amodular fashion, connect DNA-binding sequence-specificregulators to the basal transcription machinery, and facilitatechromatin remodelling and modifications (4,5).Signal transducer and activator of transcription 6 (STAT6)has an important role in regulation of interleukin-4 (IL-4)-induced gene responses. IL-4 has pleiotropic effects on theimmune system. It induces activated B lymphocytes to prolif-erate and to synthesize IgE and IgG1, and T cells to differen-tiate towards Th2 cells (6–8). IL-4 has also an important rolein the pathogenesis of asthma and allergy. IL-4 stimulationresults in activation of JAK1 and JAK3 tyrosine kinases,which in turn phosphorylate and activate STAT6 monomers.Phosphorylated STAT6 molecules dimerize and translocateinto the nucleus, where they bind to the specific recognitionsequences in the promoters of IL-4 responsive genes.The ability of STAT6 to activate transcription is dependenton the cooperation with other transcription factors and coac-tivators on the IL-4 responsive promoters. STAT6 has beenshown to cooperate with NF-kB, PU.1, IRF-4, BSAP andC/EBPb transcription factors (9–14). The mechanisms ofthis interplay vary, e.g. C/EBPb stabilizes the DNA-bindingof STAT6, whereas NF-kB and PU.1 are required for tran-scriptional activation of STAT6. In addition, transcriptionalcoregulators for STAT6 have been identified, such as theCREB-binding Protein (CBP), which acts as a coactivatorfor numerous transcription factors including all the STATProteins (15–20). CBP/p300 stimulates the transcription oftarget genes by several mechanisms; CBP/p300 regulateschromatin remodelling through intrinsic histone acetyltrans-ferase activity (21,22) and it also associates with p/CAF,another histone acetyltransferase (23). In addition, CBP/p300 can act as a coactivator by bridging transcription factorsto basal transcription machinery (24–26). Also a CBP-associated Protein NcoA-1, a member of the p160/steroidreceptor coactivator family, has been shown to function asa coactivator for STAT6 (27).The transcription activation domain (TAD) of STAT6 islocated in the C-terminus of the Protein. TADs are the mostdivergent domains among different STATs, and are capable
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the transcriptional co activator Protein P100 recruits histone acetyltransferase activity to stat6 and mediates interaction between the creb binding Protein and stat6
Journal of Biological Chemistry, 2005Co-Authors: Tuuli Valineva, Jie Yang, Riitta Palovuori, Olli SilvennoinenAbstract:Abstract STAT6 is a critical regulator of transcription for interleukin-4 (IL-4)-induced genes. Activation of gene expression involves recruitment of coactivator Proteins that function as bridging factors connecting sequence-specific transcription factors to the basal transcription machinery, and as chromatin-modifying enzymes. Coactivator Proteins CBP/p300 have been implicated in regulation of transcription in all STATs. CBP is also required for STAT6-mediated gene activation, but the underlying molecular mechanisms are still elusive. In this study we investigated the mechanisms by which STAT6 recruits CBP and chromatin-modifying activities to the promoter. Our results indicate that while STAT1-interacted directly with CBP, the interaction between STAT6 and CBP was found to be mediated through P100 Protein, a coactivator Protein that has previously been shown to stimulate the transcription of IL-4-induced genes. The staphylococcal nuclease-like (SN)-domains of P100 directly interacted with amino acids 1099–1758 of CBP, while P100 did not associate with SRC-1, another coactivator of STAT6. P100 was found to recruit histone acetyltransferase (HAT) activity to STAT6 in vivo. Chromatin immunoprecipitation studies demonstrated that P100 increases the STAT6-P100-CBP ternary complex formation in the human Igϵ promoter. P100 also increased the amount of acetylated histone H4 at the Igϵ promoter, and siRNAs directed against P100 effectively inhibited Igϵ reporter gene expression. Our results suggest that P100 has an important role in the assembly of STAT6 transcriptosome, and that P100 stimulates IL-4-dependent transcription by mediating interaction between STAT6 and CBP and recruiting chromatin modifying activities to STAT6-responsive promoters.
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tudor and nuclease like domains containing Protein P100 function as coactivators for signal transducer and activator of transcription 5
Molecular Endocrinology, 2003Co-Authors: Kirsi Paukku, Jie Yang, Olli SilvennoinenAbstract:Signal transducer and activator of transcription 5 (Stat5) plays a critical role in prolactin (PRL)-induced transcription of several milk Protein genes. Stat5-mediated gene regulation is modulated by cooperation of Stat5 with cell type- and promoter-specific transcription factors as well as by interaction with transcriptional coregulators. Recently, the expression of a tudor and staphylococcal nuclease-like domains containing Protein P100 was found to be increased in mammary epithelial cells during lactation in response to lactogenic hormones. P100 was initially identified as a transcriptional coactivator of the Epstein-Barr virus nuclear antigen 2. In this study we investigated the potential role of P100 in PRL-induced Stat5-mediated transcriptional activation. PRL stimulation increased the P100 Protein levels in HC11 mouse mammary epithelial cells. P100 did not affect the early activation events of Stat5, but P100 enhanced the Stat5-dependent transcriptional activation in HC11 cells. P100 associated wit...
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Identification of P100 as a coactivator for STAT6 that bridges STAT6 with RNA polymerase II
The EMBO Journal, 2002Co-Authors: Jie Yang, Saara Aittomäki, Marko Pesu, Kara Carter, Jussi Saarinen, Nisse Kalkkinen, Elliott Kieff, Olli SilvennoinenAbstract:STAT6 is a central mediator of IL‐4‐induced gene responses. STAT6‐mediated transcription is depend ent on the C‐terminal transcription activation domain (TAD), but the mechanisms by which STAT6 activates transcription are poorly understood. Here, we have identified the staphylococcal nuclease (SN)‐like domain and tudor domain containing Protein P100 as a STAT6 TAD interacting Protein. P100 was originally characterized as a transcriptional coactivator for Epstein–Barr virus nuclear antigen 2. STAT6 interacted with P100 in vitro and in vivo . The interaction was mediated by the TAD domain of STAT6 and the SN‐like domain of P100. P100 did not affect the immediate activation events of STAT6, but enhanced STAT6‐mediated transcriptional activation and the IL‐4‐induced Igϵ gene transcription in human B‐cell line. Finally, P100 associated with the large subunit of RNA polymerase II and was mediating interaction between STAT6 and RNA polymerase II. These findings identify P100 as a novel coactivator for STAT6 and suggest that P100 functions as a bridging factor between STAT6 and the basal transcription machinery.
Renato C Monteiro - One of the best experts on this subject based on the ideXlab platform.
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t cell activation through thy 1 is associated with the expression of a surface Protein P100 on a subset of cd4 cells
International Immunology, 1995Co-Authors: Agnes Lehuen, John F Kearney, Lucie Beaudoin, Muriel Bernard, Jeanfrancois Bach, Renato C MonteiroAbstract:: Thy-1 molecules, which lack a transmembrane domain, can nonetheless induce T cell activation; it has thus been suggested that a separate transmembrane molecule associated with Thy-1 is required for signal transduction. We have previously characterized a transmembrane Protein with an Mr of 100,000 (P100), which is non-covalently bound to two glycosyl-phosphatidylinositol (GPI)-linked molecules, Thy-1 and ThB. P100 is selectively expressed on the T cell surface and divides peripheral CD4 cells into two subpopulations. This differential expression on CD4 cells allowed us to investigate the role of P100 in signal transduction through Thy-1 molecules. Here we report that only P100+ CD4 cells proliferate and release cytokines in response to cross-linkage of Thy-1, although both P100+ and P100- CD4 cells strongly express Thy-1 on their surfaces. Control stimulation by anti-CD3 antibodies or concanavalin A induces identical thymidine uptake by the two CD4 cell populations. Interestingly, these two populations of CD4 cells had different cytokine release profiles after activation through CD3: only P100+ CD4 cells released high amounts of IL-2 and IFN-gamma, whereas both populations released IL-4. P100 expression correlates with the induction of homotypic aggregation of T cells after Thy-1 triggering. P100 is associated with kinase activity (fyn and lck), and phosphorylated Proteins of 90, 59, 57 and 33 kDa co-precipitate with Thy-1 only in P100+ CD4 cells. Altogether, these data suggest that P100 is involved in signal transduction through Thy-1. P100 expression by activated CD4 cells in vivo may be relevant to the proposed function of Thy-1 as an accessory signaling molecule in cell activation.
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identification of a surface Protein P100 associated with two glycosyl phosphatidylinositol linked molecules thy 1 and thb by natural anti lymphocyte autoantibodies
European Journal of Immunology, 1992Co-Authors: Agnes Lehuen, Renato C Monteiro, John F KearneyAbstract:Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22). These mAb identified a 100-kDa Protein (P100) on the surface of thymocytes. This Protein resolved into 70-kDa polypeptide chains under reducing conditions. Inhibition experiments as well as antibody immunoprecipitations in the presence of mild detergents revealed non-covalent association of the P100 with Thy-1 and ThB. A similar multimolecular complex was identified following chemical cross-linking of thymocyte surface Proteins. Analysis of several Thy-1-defective mutant cells lines, and thymocytes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) showed that the expression of P100 was strongly influenced by Thy-1 molecule. The P100 was resistant to PI-PLC treatment and was not released into the supernatant as was the case for Thy-1 and ThB molecules. These data lead us to propose that the P100 is a transmembrane Protein, the expression of which in the plasma membrane is dependent on the association or presence of Thy-1 molecule.
Jie Yang - One of the best experts on this subject based on the ideXlab platform.
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transcriptional co activator Protein P100 interacts with snrnp Proteins and facilitates the assembly of the spliceosome
Nucleic Acids Research, 2007Co-Authors: Jie Yang, Tuuli Valineva, Jingxin Hong, Tianxu Bu, Ole Norregaard Jensen, Mikko J Frilander, Olli SilvennoinenAbstract:Transcription and pre-mRNA splicing are the key nuclear processes in eukaryotic gene expression, and identification of factors common to both processes has suggested that they are functionally coordinated. P100 Protein has been shown to function as a transcriptional co-activator for several transcription factors. P100 consists of staphylococcal nuclease (SN)-like and Tudor-SN (TSN) domains of which the SN-like domains have been shown to function in transcription, but the function of TSN domain has remained elusive. Here we identified interaction between P100 and small nuclear ribonucleoProteins (snRNP) that function in pre-mRNA splicing. The TSN domain of P100 specifically interacts with components of the U5 snRNP, but also with the other spliceosomal snRNPs. In vitro splicing assays revealed that the purified P100, and specifically the TSN domain of P100, accelerates the kinetics of the spliceosome assembly, particularly the formation of complex A, and the transition from complex A to B. Consistently, the P100 Protein, as well as the separated TSN domain, enhanced the kinetics of the first step of splicing in an in vitro splicing assay in dose-dependent manner. Thus our results suggest that P100 Protein is a novel dual function regulator of gene expression that participates via distinct domains in both transcription and splicing.
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Characterization of RNA helicase A as component of STAT6-dependent enhanceosome
Nucleic Acids Research, 2006Co-Authors: Tuuli Valineva, Jie Yang, Olli SilvennoinenAbstract:ABSTRACTSignal transducer and activator of transcription6 (STAT6) is a regulator of transcription forinterleukin-4 (IL-4)-induced genes. The ability ofSTAT6 to activate transcription depends on func-tional interaction with other transcription factorsand coactivators. We have characterized the mecha-nism of STAT6-mediated transcriptional activationby identifyingSTAT6 transcription activation domain(TAD) interacting nuclear Proteins. The first of theidentified Proteins was coactivator Protein P100,which regulates IL-4-induced transcription by con-necting STAT6 with other transcriptional regulators.Here, we describe RNA helicase A (RHA) as a novelcomponent of STAT6 transcriptosome. In vitro andin vivo experiments indicated that RHA did notdirectly interact with STAT6, but P100 Protein wasfound to mediate the assembly of the ternarycomplex of STAT6-P100-RHA. In chromatin immuno-precipitation studies RHA together with P100enhanced the binding of STAT6 on the human Ig « promoter after IL-4 stimulation. RHA enhanced theIL-4-induced transcription, and the participation ofRHA in IL-4-regulated transcription was supportedby RNAi experiments. Our results suggest that RHAhas an important role in the assembly of STAT6transcriptosome. As RHA is also known to interactwith chromatin modifying Proteins, the RHA con-taining Protein complexes may facilitate the entryof transcriptional apparatus to the IL-4 responsivepromoters.INTRODUCTIONRegulation of transcription is dependent both on generaltranscription factors as well as transcriptional activatorsand coactivators. These Proteins are assembled into a nucleo-Protein complex called the enhanceosome (1–3). In theenhanceosome transcriptional coactivators form multifunc-tional Protein–Protein complexes, which are assembled in amodular fashion, connect DNA-binding sequence-specificregulators to the basal transcription machinery, and facilitatechromatin remodelling and modifications (4,5).Signal transducer and activator of transcription 6 (STAT6)has an important role in regulation of interleukin-4 (IL-4)-induced gene responses. IL-4 has pleiotropic effects on theimmune system. It induces activated B lymphocytes to prolif-erate and to synthesize IgE and IgG1, and T cells to differen-tiate towards Th2 cells (6–8). IL-4 has also an important rolein the pathogenesis of asthma and allergy. IL-4 stimulationresults in activation of JAK1 and JAK3 tyrosine kinases,which in turn phosphorylate and activate STAT6 monomers.Phosphorylated STAT6 molecules dimerize and translocateinto the nucleus, where they bind to the specific recognitionsequences in the promoters of IL-4 responsive genes.The ability of STAT6 to activate transcription is dependenton the cooperation with other transcription factors and coac-tivators on the IL-4 responsive promoters. STAT6 has beenshown to cooperate with NF-kB, PU.1, IRF-4, BSAP andC/EBPb transcription factors (9–14). The mechanisms ofthis interplay vary, e.g. C/EBPb stabilizes the DNA-bindingof STAT6, whereas NF-kB and PU.1 are required for tran-scriptional activation of STAT6. In addition, transcriptionalcoregulators for STAT6 have been identified, such as theCREB-binding Protein (CBP), which acts as a coactivatorfor numerous transcription factors including all the STATProteins (15–20). CBP/p300 stimulates the transcription oftarget genes by several mechanisms; CBP/p300 regulateschromatin remodelling through intrinsic histone acetyltrans-ferase activity (21,22) and it also associates with p/CAF,another histone acetyltransferase (23). In addition, CBP/p300 can act as a coactivator by bridging transcription factorsto basal transcription machinery (24–26). Also a CBP-associated Protein NcoA-1, a member of the p160/steroidreceptor coactivator family, has been shown to function asa coactivator for STAT6 (27).The transcription activation domain (TAD) of STAT6 islocated in the C-terminus of the Protein. TADs are the mostdivergent domains among different STATs, and are capable
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the transcriptional co activator Protein P100 recruits histone acetyltransferase activity to stat6 and mediates interaction between the creb binding Protein and stat6
Journal of Biological Chemistry, 2005Co-Authors: Tuuli Valineva, Jie Yang, Riitta Palovuori, Olli SilvennoinenAbstract:Abstract STAT6 is a critical regulator of transcription for interleukin-4 (IL-4)-induced genes. Activation of gene expression involves recruitment of coactivator Proteins that function as bridging factors connecting sequence-specific transcription factors to the basal transcription machinery, and as chromatin-modifying enzymes. Coactivator Proteins CBP/p300 have been implicated in regulation of transcription in all STATs. CBP is also required for STAT6-mediated gene activation, but the underlying molecular mechanisms are still elusive. In this study we investigated the mechanisms by which STAT6 recruits CBP and chromatin-modifying activities to the promoter. Our results indicate that while STAT1-interacted directly with CBP, the interaction between STAT6 and CBP was found to be mediated through P100 Protein, a coactivator Protein that has previously been shown to stimulate the transcription of IL-4-induced genes. The staphylococcal nuclease-like (SN)-domains of P100 directly interacted with amino acids 1099–1758 of CBP, while P100 did not associate with SRC-1, another coactivator of STAT6. P100 was found to recruit histone acetyltransferase (HAT) activity to STAT6 in vivo. Chromatin immunoprecipitation studies demonstrated that P100 increases the STAT6-P100-CBP ternary complex formation in the human Igϵ promoter. P100 also increased the amount of acetylated histone H4 at the Igϵ promoter, and siRNAs directed against P100 effectively inhibited Igϵ reporter gene expression. Our results suggest that P100 has an important role in the assembly of STAT6 transcriptosome, and that P100 stimulates IL-4-dependent transcription by mediating interaction between STAT6 and CBP and recruiting chromatin modifying activities to STAT6-responsive promoters.
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tudor and nuclease like domains containing Protein P100 function as coactivators for signal transducer and activator of transcription 5
Molecular Endocrinology, 2003Co-Authors: Kirsi Paukku, Jie Yang, Olli SilvennoinenAbstract:Signal transducer and activator of transcription 5 (Stat5) plays a critical role in prolactin (PRL)-induced transcription of several milk Protein genes. Stat5-mediated gene regulation is modulated by cooperation of Stat5 with cell type- and promoter-specific transcription factors as well as by interaction with transcriptional coregulators. Recently, the expression of a tudor and staphylococcal nuclease-like domains containing Protein P100 was found to be increased in mammary epithelial cells during lactation in response to lactogenic hormones. P100 was initially identified as a transcriptional coactivator of the Epstein-Barr virus nuclear antigen 2. In this study we investigated the potential role of P100 in PRL-induced Stat5-mediated transcriptional activation. PRL stimulation increased the P100 Protein levels in HC11 mouse mammary epithelial cells. P100 did not affect the early activation events of Stat5, but P100 enhanced the Stat5-dependent transcriptional activation in HC11 cells. P100 associated wit...
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Identification of P100 as a coactivator for STAT6 that bridges STAT6 with RNA polymerase II
The EMBO Journal, 2002Co-Authors: Jie Yang, Saara Aittomäki, Marko Pesu, Kara Carter, Jussi Saarinen, Nisse Kalkkinen, Elliott Kieff, Olli SilvennoinenAbstract:STAT6 is a central mediator of IL‐4‐induced gene responses. STAT6‐mediated transcription is depend ent on the C‐terminal transcription activation domain (TAD), but the mechanisms by which STAT6 activates transcription are poorly understood. Here, we have identified the staphylococcal nuclease (SN)‐like domain and tudor domain containing Protein P100 as a STAT6 TAD interacting Protein. P100 was originally characterized as a transcriptional coactivator for Epstein–Barr virus nuclear antigen 2. STAT6 interacted with P100 in vitro and in vivo . The interaction was mediated by the TAD domain of STAT6 and the SN‐like domain of P100. P100 did not affect the immediate activation events of STAT6, but enhanced STAT6‐mediated transcriptional activation and the IL‐4‐induced Igϵ gene transcription in human B‐cell line. Finally, P100 associated with the large subunit of RNA polymerase II and was mediating interaction between STAT6 and RNA polymerase II. These findings identify P100 as a novel coactivator for STAT6 and suggest that P100 functions as a bridging factor between STAT6 and the basal transcription machinery.
John F Kearney - One of the best experts on this subject based on the ideXlab platform.
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t cell activation through thy 1 is associated with the expression of a surface Protein P100 on a subset of cd4 cells
International Immunology, 1995Co-Authors: Agnes Lehuen, John F Kearney, Lucie Beaudoin, Muriel Bernard, Jeanfrancois Bach, Renato C MonteiroAbstract:: Thy-1 molecules, which lack a transmembrane domain, can nonetheless induce T cell activation; it has thus been suggested that a separate transmembrane molecule associated with Thy-1 is required for signal transduction. We have previously characterized a transmembrane Protein with an Mr of 100,000 (P100), which is non-covalently bound to two glycosyl-phosphatidylinositol (GPI)-linked molecules, Thy-1 and ThB. P100 is selectively expressed on the T cell surface and divides peripheral CD4 cells into two subpopulations. This differential expression on CD4 cells allowed us to investigate the role of P100 in signal transduction through Thy-1 molecules. Here we report that only P100+ CD4 cells proliferate and release cytokines in response to cross-linkage of Thy-1, although both P100+ and P100- CD4 cells strongly express Thy-1 on their surfaces. Control stimulation by anti-CD3 antibodies or concanavalin A induces identical thymidine uptake by the two CD4 cell populations. Interestingly, these two populations of CD4 cells had different cytokine release profiles after activation through CD3: only P100+ CD4 cells released high amounts of IL-2 and IFN-gamma, whereas both populations released IL-4. P100 expression correlates with the induction of homotypic aggregation of T cells after Thy-1 triggering. P100 is associated with kinase activity (fyn and lck), and phosphorylated Proteins of 90, 59, 57 and 33 kDa co-precipitate with Thy-1 only in P100+ CD4 cells. Altogether, these data suggest that P100 is involved in signal transduction through Thy-1. P100 expression by activated CD4 cells in vivo may be relevant to the proposed function of Thy-1 as an accessory signaling molecule in cell activation.
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identification of a surface Protein P100 associated with two glycosyl phosphatidylinositol linked molecules thy 1 and thb by natural anti lymphocyte autoantibodies
European Journal of Immunology, 1992Co-Authors: Agnes Lehuen, Renato C Monteiro, John F KearneyAbstract:Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22). These mAb identified a 100-kDa Protein (P100) on the surface of thymocytes. This Protein resolved into 70-kDa polypeptide chains under reducing conditions. Inhibition experiments as well as antibody immunoprecipitations in the presence of mild detergents revealed non-covalent association of the P100 with Thy-1 and ThB. A similar multimolecular complex was identified following chemical cross-linking of thymocyte surface Proteins. Analysis of several Thy-1-defective mutant cells lines, and thymocytes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) showed that the expression of P100 was strongly influenced by Thy-1 molecule. The P100 was resistant to PI-PLC treatment and was not released into the supernatant as was the case for Thy-1 and ThB molecules. These data lead us to propose that the P100 is a transmembrane Protein, the expression of which in the plasma membrane is dependent on the association or presence of Thy-1 molecule.
Agnes Lehuen - One of the best experts on this subject based on the ideXlab platform.
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t cell activation through thy 1 is associated with the expression of a surface Protein P100 on a subset of cd4 cells
International Immunology, 1995Co-Authors: Agnes Lehuen, John F Kearney, Lucie Beaudoin, Muriel Bernard, Jeanfrancois Bach, Renato C MonteiroAbstract:: Thy-1 molecules, which lack a transmembrane domain, can nonetheless induce T cell activation; it has thus been suggested that a separate transmembrane molecule associated with Thy-1 is required for signal transduction. We have previously characterized a transmembrane Protein with an Mr of 100,000 (P100), which is non-covalently bound to two glycosyl-phosphatidylinositol (GPI)-linked molecules, Thy-1 and ThB. P100 is selectively expressed on the T cell surface and divides peripheral CD4 cells into two subpopulations. This differential expression on CD4 cells allowed us to investigate the role of P100 in signal transduction through Thy-1 molecules. Here we report that only P100+ CD4 cells proliferate and release cytokines in response to cross-linkage of Thy-1, although both P100+ and P100- CD4 cells strongly express Thy-1 on their surfaces. Control stimulation by anti-CD3 antibodies or concanavalin A induces identical thymidine uptake by the two CD4 cell populations. Interestingly, these two populations of CD4 cells had different cytokine release profiles after activation through CD3: only P100+ CD4 cells released high amounts of IL-2 and IFN-gamma, whereas both populations released IL-4. P100 expression correlates with the induction of homotypic aggregation of T cells after Thy-1 triggering. P100 is associated with kinase activity (fyn and lck), and phosphorylated Proteins of 90, 59, 57 and 33 kDa co-precipitate with Thy-1 only in P100+ CD4 cells. Altogether, these data suggest that P100 is involved in signal transduction through Thy-1. P100 expression by activated CD4 cells in vivo may be relevant to the proposed function of Thy-1 as an accessory signaling molecule in cell activation.
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identification of a surface Protein P100 associated with two glycosyl phosphatidylinositol linked molecules thy 1 and thb by natural anti lymphocyte autoantibodies
European Journal of Immunology, 1992Co-Authors: Agnes Lehuen, Renato C Monteiro, John F KearneyAbstract:Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22). These mAb identified a 100-kDa Protein (P100) on the surface of thymocytes. This Protein resolved into 70-kDa polypeptide chains under reducing conditions. Inhibition experiments as well as antibody immunoprecipitations in the presence of mild detergents revealed non-covalent association of the P100 with Thy-1 and ThB. A similar multimolecular complex was identified following chemical cross-linking of thymocyte surface Proteins. Analysis of several Thy-1-defective mutant cells lines, and thymocytes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) showed that the expression of P100 was strongly influenced by Thy-1 molecule. The P100 was resistant to PI-PLC treatment and was not released into the supernatant as was the case for Thy-1 and ThB molecules. These data lead us to propose that the P100 is a transmembrane Protein, the expression of which in the plasma membrane is dependent on the association or presence of Thy-1 molecule.
