The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Klaus Rajewsky - One of the best experts on this subject based on the ideXlab platform.
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hyperactivation of nuclear factor of activated t cells 1 nfat1 in t cells attenuates severity of murine autoimmune encephalomyelitis
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Srimoyee Ghosh, Yoshiteru Sasaki, Klaus Rajewsky, Sergei B Koralov, Irena Stevanovic, Mark S Sundrud, Anjana Rao, Martin MullerAbstract:Nuclear factor of activated T cells (NFAT) proteins are a group of Ca2+-regulated transcription factors residing in the cytoplasm of resting cells. Dephosphorylation by calcineurin results in nuclear translocation of NFAT and subsequent expression of target genes; rephosphorylation by kinases, including casein kinase 1 (CK1), restores NFAT to its latent state in the cytoplasm. We engineered a hyperactivable version of NFAT1 with increased affinity for calcineurin and decreased affinity for casein kinase 1. Mice expressing hyperactivable NFAT1 in their T-cell compartment exhibited a dramatically increased frequency of both IL-17– and IL-10–producing cells after differentiation under Th17 conditions—this was associated with direct binding of NFAT1 to distal regulatory regions of Il-17 and Il-10 gene loci in Th17 cells. Despite higher IL-17 production in culture, the mice were significantly less prone to myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalomyelitis than controls, correlating with increased production of the immunomodulatory cytokine IL-10 and enhanced accumulation of regulatory T cells within the CNS. Thus, NFAT hyperactivation paradoxically leads to decreased susceptibility to experimental autoimmune encephalomyelitis, supporting previous observations linking defects in Ca2+/NFAT signaling to lymphoproliferation and autoimmune disease.
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The Role of the Transcription Factor NFAT in the Pathogenesis of Non-Hodgkin’s Lymphomas.
Blood, 2006Co-Authors: Martin R. Mueller, Yoshiteru Sasaki, Sonia Sharma, Klaus RajewskyAbstract:NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon Dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT translocates to the nucleus, where it induces the transcription of a large number of genes necessary for a productive immune response. NFAT signalling has also been implicated in lymphocyte homeostasis and its deregulation has been suggested to be involved in the pathogenesis of different malignancies. A recent immunohistochemical evaluation of approximately 300 Non-Hodgkin’s Lymphoma biopsy samples showed overexpression of NFAT2 in the majority of specimens with strong nuclear translocation in certain histologic subtypes (DLBCL, Burkitt’s Lymphoma) presumably reflecting activation of the NFAT pathway as part of their pathogenesis. Other recent studies have shown that NFAT activation leads to increased expression of different cell survival factors (CD154, BLyS) in several lymphoma subtypes (DLBCL, MCL). To study the role of constitutive activation of the NFAT pathway on lymphomagenesis, we generated several hyperactivable NFAT mutants which will be used to generate transgenic mice expressing the mutant proteins from the ROSA26 locus. Here, we present the in vitro characterization of these hyperactivable NFAT proteins in cell lines and primary lymphocytes. The major docking site for calcineurin is located at the N terminus of the NFAT regulatory domain and has the consensus sequence PxIxIT (e.g. SPRIEIT in NFAT1 and NFAT2). Substitution of the SPRIEIT sequence of NFAT with HPVIVIT, a higher-affinity version obtained by peptide selection, increases the basal calcineurin sensitivity of the protein significantly. Similarly, a major kinase for NFAT is CK1, and mutation of the CK1 docking site (FSILF to ASILA in NFAT1, FDFEF to ADAEA in NFAT2) also leads to partial nuclear localization of NFAT proteins by decreasing rephosphorylation and nuclear export. In the current analysis we compared the different hyperactivable NFAT proteins with respect to Dephosphorylation status and nuclear translocation using western blotting and immunocytochemistry. Whereas the wildtype NFAT protein was entirely localized in the cytoplasm and completely phosphorylated under resting conditions, we observed an increasing degree of nuclear translocation and Dephosphorylation for the different mutant proteins (ASILA 20%, VIVIT 30–40%, ASILA-VIVIT 50–70%). This system will allow us to study the impact of different levels of NFAT activation on the pathogenesis of lymphomas in vivo.
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the role of the transcription factor nfat in the pathogenesis of non hodgkin s lymphomas
Blood, 2006Co-Authors: Martin R. Mueller, Yoshiteru Sasaki, Sonia Sharma, Klaus RajewskyAbstract:NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon Dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT translocates to the nucleus, where it induces the transcription of a large number of genes necessary for a productive immune response. NFAT signalling has also been implicated in lymphocyte homeostasis and its deregulation has been suggested to be involved in the pathogenesis of different malignancies. A recent immunohistochemical evaluation of approximately 300 Non-Hodgkin’s Lymphoma biopsy samples showed overexpression of NFAT2 in the majority of specimens with strong nuclear translocation in certain histologic subtypes (DLBCL, Burkitt’s Lymphoma) presumably reflecting activation of the NFAT pathway as part of their pathogenesis. Other recent studies have shown that NFAT activation leads to increased expression of different cell survival factors (CD154, BLyS) in several lymphoma subtypes (DLBCL, MCL). To study the role of constitutive activation of the NFAT pathway on lymphomagenesis, we generated several hyperactivable NFAT mutants which will be used to generate transgenic mice expressing the mutant proteins from the ROSA26 locus. Here, we present the in vitro characterization of these hyperactivable NFAT proteins in cell lines and primary lymphocytes. The major docking site for calcineurin is located at the N terminus of the NFAT regulatory domain and has the consensus sequence PxIxIT (e.g. SPRIEIT in NFAT1 and NFAT2). Substitution of the SPRIEIT sequence of NFAT with HPVIVIT, a higher-affinity version obtained by peptide selection, increases the basal calcineurin sensitivity of the protein significantly. Similarly, a major kinase for NFAT is CK1, and mutation of the CK1 docking site (FSILF to ASILA in NFAT1, FDFEF to ADAEA in NFAT2) also leads to partial nuclear localization of NFAT proteins by decreasing rephosphorylation and nuclear export. In the current analysis we compared the different hyperactivable NFAT proteins with respect to Dephosphorylation status and nuclear translocation using western blotting and immunocytochemistry. Whereas the wildtype NFAT protein was entirely localized in the cytoplasm and completely phosphorylated under resting conditions, we observed an increasing degree of nuclear translocation and Dephosphorylation for the different mutant proteins (ASILA 20%, VIVIT 30–40%, ASILA-VIVIT 50–70%). This system will allow us to study the impact of different levels of NFAT activation on the pathogenesis of lymphomas in vivo.
Sonia Sharma - One of the best experts on this subject based on the ideXlab platform.
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Dephosphorylation of the nuclear factor of activated t cells nfat transcription factor is regulated by an rna protein scaffold complex
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Sonia Sharma, Valentina A. Schmidt, Gregory M Findlay, Hozefa S Bandukwala, Shalini Oberdoerffer, Beate Baust, Zhigang Li, Patrick G Hogan, David B. SacksAbstract:Nuclear factor of activated T cells (NFAT) proteins are Ca2+-regulated transcription factors that control gene expression in many cell types. NFAT proteins are heavily phosphorylated and reside in the cytoplasm of resting cells; when cells are stimulated by a rise in intracellular Ca2+, NFAT proteins are dephosphorylated by the Ca2+/calmodulin-dependent phosphatase calcineurin and translocate to the nucleus to activate target gene expression. Here we show that phosphorylated NFAT1 is present in a large cytoplasmic RNA-protein scaffold complex that contains a long intergenic noncoding RNA (lincRNA), NRON [noncoding (RNA) repressor of NFAT]; a scaffold protein, IQ motif containing GTPase activating protein (IQGAP); and three NFAT kinases, casein kinase 1, glycogen synthase kinase 3, and dual specificity tyrosine phosphorylation regulated kinase. Combined knockdown of NRON and IQGAP1 increased NFAT Dephosphorylation and nuclear import exclusively after stimulation, without affecting the rate of NFAT rephosphorylation and nuclear export; and both NRON-depleted T cells and T cells from IQGAP1-deficient mice showed increased production of NFAT-dependent cytokines. Our results provide evidence that a complex of lincRNA and protein forms a scaffold for a latent transcription factor and its regulatory kinases, and support an emerging consensus that lincRNAs that bind transcriptional regulators have a similar scaffold function.
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The Role of the Transcription Factor NFAT in the Pathogenesis of Non-Hodgkin’s Lymphomas.
Blood, 2006Co-Authors: Martin R. Mueller, Yoshiteru Sasaki, Sonia Sharma, Klaus RajewskyAbstract:NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon Dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT translocates to the nucleus, where it induces the transcription of a large number of genes necessary for a productive immune response. NFAT signalling has also been implicated in lymphocyte homeostasis and its deregulation has been suggested to be involved in the pathogenesis of different malignancies. A recent immunohistochemical evaluation of approximately 300 Non-Hodgkin’s Lymphoma biopsy samples showed overexpression of NFAT2 in the majority of specimens with strong nuclear translocation in certain histologic subtypes (DLBCL, Burkitt’s Lymphoma) presumably reflecting activation of the NFAT pathway as part of their pathogenesis. Other recent studies have shown that NFAT activation leads to increased expression of different cell survival factors (CD154, BLyS) in several lymphoma subtypes (DLBCL, MCL). To study the role of constitutive activation of the NFAT pathway on lymphomagenesis, we generated several hyperactivable NFAT mutants which will be used to generate transgenic mice expressing the mutant proteins from the ROSA26 locus. Here, we present the in vitro characterization of these hyperactivable NFAT proteins in cell lines and primary lymphocytes. The major docking site for calcineurin is located at the N terminus of the NFAT regulatory domain and has the consensus sequence PxIxIT (e.g. SPRIEIT in NFAT1 and NFAT2). Substitution of the SPRIEIT sequence of NFAT with HPVIVIT, a higher-affinity version obtained by peptide selection, increases the basal calcineurin sensitivity of the protein significantly. Similarly, a major kinase for NFAT is CK1, and mutation of the CK1 docking site (FSILF to ASILA in NFAT1, FDFEF to ADAEA in NFAT2) also leads to partial nuclear localization of NFAT proteins by decreasing rephosphorylation and nuclear export. In the current analysis we compared the different hyperactivable NFAT proteins with respect to Dephosphorylation status and nuclear translocation using western blotting and immunocytochemistry. Whereas the wildtype NFAT protein was entirely localized in the cytoplasm and completely phosphorylated under resting conditions, we observed an increasing degree of nuclear translocation and Dephosphorylation for the different mutant proteins (ASILA 20%, VIVIT 30–40%, ASILA-VIVIT 50–70%). This system will allow us to study the impact of different levels of NFAT activation on the pathogenesis of lymphomas in vivo.
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the role of the transcription factor nfat in the pathogenesis of non hodgkin s lymphomas
Blood, 2006Co-Authors: Martin R. Mueller, Yoshiteru Sasaki, Sonia Sharma, Klaus RajewskyAbstract:NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon Dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT translocates to the nucleus, where it induces the transcription of a large number of genes necessary for a productive immune response. NFAT signalling has also been implicated in lymphocyte homeostasis and its deregulation has been suggested to be involved in the pathogenesis of different malignancies. A recent immunohistochemical evaluation of approximately 300 Non-Hodgkin’s Lymphoma biopsy samples showed overexpression of NFAT2 in the majority of specimens with strong nuclear translocation in certain histologic subtypes (DLBCL, Burkitt’s Lymphoma) presumably reflecting activation of the NFAT pathway as part of their pathogenesis. Other recent studies have shown that NFAT activation leads to increased expression of different cell survival factors (CD154, BLyS) in several lymphoma subtypes (DLBCL, MCL). To study the role of constitutive activation of the NFAT pathway on lymphomagenesis, we generated several hyperactivable NFAT mutants which will be used to generate transgenic mice expressing the mutant proteins from the ROSA26 locus. Here, we present the in vitro characterization of these hyperactivable NFAT proteins in cell lines and primary lymphocytes. The major docking site for calcineurin is located at the N terminus of the NFAT regulatory domain and has the consensus sequence PxIxIT (e.g. SPRIEIT in NFAT1 and NFAT2). Substitution of the SPRIEIT sequence of NFAT with HPVIVIT, a higher-affinity version obtained by peptide selection, increases the basal calcineurin sensitivity of the protein significantly. Similarly, a major kinase for NFAT is CK1, and mutation of the CK1 docking site (FSILF to ASILA in NFAT1, FDFEF to ADAEA in NFAT2) also leads to partial nuclear localization of NFAT proteins by decreasing rephosphorylation and nuclear export. In the current analysis we compared the different hyperactivable NFAT proteins with respect to Dephosphorylation status and nuclear translocation using western blotting and immunocytochemistry. Whereas the wildtype NFAT protein was entirely localized in the cytoplasm and completely phosphorylated under resting conditions, we observed an increasing degree of nuclear translocation and Dephosphorylation for the different mutant proteins (ASILA 20%, VIVIT 30–40%, ASILA-VIVIT 50–70%). This system will allow us to study the impact of different levels of NFAT activation on the pathogenesis of lymphomas in vivo.
David Ron - One of the best experts on this subject based on the ideXlab platform.
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Author response: PPP1R15A-mediated Dephosphorylation of eIF2α is unaffected by Sephin1 or Guanabenz
eLife, 2017Co-Authors: Ana Crespillo-casado, Peter M Fischer, Joseph E Chambers, Stefan J Marciniak, David RonAbstract:Dephosphorylation of translation initiation factor 2 (eIF2α) terminates signalling in the mammalian integrated stress response (ISR) and has emerged as a promising target for modifying the course of protein misfolding diseases. The [(o-chlorobenzylidene)amino]guanidines (Guanabenz and Sephin1) have been proposed to exert protective effects against misfolding by interfering with eIF2α-P Dephosphorylation through selective disruption of a PP1-PPP1R15A holophosphatase complex. Surprisingly, they proved inert in vitro affecting neither stability of the PP1-PPP1R15A complex nor substrate-specific Dephosphorylation. Furthermore, eIF2α-P Dephosphorylation, assessed by a kinase shut-off experiment, progressed normally in Sephin1-treated cells. Consistent with its role in defending proteostasis, Sephin1 attenuated the IRE1 branch of the endoplasmic reticulum unfolded protein response. However, repression was noted in both wildtype and Ppp1r15a deleted cells and in cells rendered ISR-deficient by CRISPR editing of the Eif2s1 locus to encode a non-phosphorylatable eIF2α (eIF2αS51A). These findings challenge the view that [(o-chlorobenzylidene)amino]guanidines restore proteostasis by interfering with eIF2α-P Dephosphorylation.
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ppp1r15a mediated Dephosphorylation of eif2α is unaffected by sephin1 or guanabenz
eLife, 2017Co-Authors: Ana Crespillocasado, Joseph E Chambers, Peter M Fischer, Stefan J Marciniak, David RonAbstract:Dephosphorylation of translation initiation factor 2 (eIF2α) terminates signalling in the mammalian integrated stress response (ISR) and has emerged as a promising target for modifying the course of protein misfolding diseases. The [(o-chlorobenzylidene)amino]guanidines (Guanabenz and Sephin1) have been proposed to exert protective effects against misfolding by interfering with eIF2α-P Dephosphorylation through selective disruption of a PP1-PPP1R15A holophosphatase complex. Surprisingly, they proved inert in vitro affecting neither stability of the PP1-PPP1R15A complex nor substrate-specific Dephosphorylation. Furthermore, eIF2α-P Dephosphorylation, assessed by a kinase shut-off experiment, progressed normally in Sephin1-treated cells. Consistent with its role in defending proteostasis, Sephin1 attenuated the IRE1 branch of the endoplasmic reticulum unfolded protein response. However, repression was noted in both wildtype and Ppp1r15a deleted cells and in cells rendered ISR-deficient by CRISPR editing of the Eif2s1 locus to encode a non-phosphorylatable eIF2α (eIF2αS51A). These findings challenge the view that [(o-chlorobenzylidene)amino]guanidines restore proteostasis by interfering with eIF2α-P Dephosphorylation.
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a selective inhibitor of eif2alpha Dephosphorylation protects cells from er stress
Science, 2005Co-Authors: Michael Boyce, Kevin F Bryant, Celine Jousse, Kai Long, Heather P Harding, Donalyn Scheuner, Randal J Kaufman, Donald M Coen, David Ron, Junying YuanAbstract:Most protein phosphatases have little intrinsic substrate specificity, making selective pharmacological inhibition of specific Dephosphorylation reactions a challenging problem. In a screen for small molecules that protect cells from endoplasmic reticulum (ER) stress, we identified salubrinal, a selective inhibitor of cellular complexes that dephosphorylate eukaryotic translation initiation factor 2 subunit alpha (eIF2alpha). Salubrinal also blocks eIF2alpha Dephosphorylation mediated by a herpes simplex virus protein and inhibits viral replication. These results suggest that selective chemical inhibitors of eIF2alpha Dephosphorylation may be useful in diseases involving ER stress or viral infection. More broadly, salubrinal demonstrates the feasibility of selective pharmacological targeting of cellular Dephosphorylation events.
Yoshiteru Sasaki - One of the best experts on this subject based on the ideXlab platform.
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hyperactivation of nuclear factor of activated t cells 1 nfat1 in t cells attenuates severity of murine autoimmune encephalomyelitis
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Srimoyee Ghosh, Yoshiteru Sasaki, Klaus Rajewsky, Sergei B Koralov, Irena Stevanovic, Mark S Sundrud, Anjana Rao, Martin MullerAbstract:Nuclear factor of activated T cells (NFAT) proteins are a group of Ca2+-regulated transcription factors residing in the cytoplasm of resting cells. Dephosphorylation by calcineurin results in nuclear translocation of NFAT and subsequent expression of target genes; rephosphorylation by kinases, including casein kinase 1 (CK1), restores NFAT to its latent state in the cytoplasm. We engineered a hyperactivable version of NFAT1 with increased affinity for calcineurin and decreased affinity for casein kinase 1. Mice expressing hyperactivable NFAT1 in their T-cell compartment exhibited a dramatically increased frequency of both IL-17– and IL-10–producing cells after differentiation under Th17 conditions—this was associated with direct binding of NFAT1 to distal regulatory regions of Il-17 and Il-10 gene loci in Th17 cells. Despite higher IL-17 production in culture, the mice were significantly less prone to myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalomyelitis than controls, correlating with increased production of the immunomodulatory cytokine IL-10 and enhanced accumulation of regulatory T cells within the CNS. Thus, NFAT hyperactivation paradoxically leads to decreased susceptibility to experimental autoimmune encephalomyelitis, supporting previous observations linking defects in Ca2+/NFAT signaling to lymphoproliferation and autoimmune disease.
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The Role of the Transcription Factor NFAT in the Pathogenesis of Non-Hodgkin’s Lymphomas.
Blood, 2006Co-Authors: Martin R. Mueller, Yoshiteru Sasaki, Sonia Sharma, Klaus RajewskyAbstract:NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon Dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT translocates to the nucleus, where it induces the transcription of a large number of genes necessary for a productive immune response. NFAT signalling has also been implicated in lymphocyte homeostasis and its deregulation has been suggested to be involved in the pathogenesis of different malignancies. A recent immunohistochemical evaluation of approximately 300 Non-Hodgkin’s Lymphoma biopsy samples showed overexpression of NFAT2 in the majority of specimens with strong nuclear translocation in certain histologic subtypes (DLBCL, Burkitt’s Lymphoma) presumably reflecting activation of the NFAT pathway as part of their pathogenesis. Other recent studies have shown that NFAT activation leads to increased expression of different cell survival factors (CD154, BLyS) in several lymphoma subtypes (DLBCL, MCL). To study the role of constitutive activation of the NFAT pathway on lymphomagenesis, we generated several hyperactivable NFAT mutants which will be used to generate transgenic mice expressing the mutant proteins from the ROSA26 locus. Here, we present the in vitro characterization of these hyperactivable NFAT proteins in cell lines and primary lymphocytes. The major docking site for calcineurin is located at the N terminus of the NFAT regulatory domain and has the consensus sequence PxIxIT (e.g. SPRIEIT in NFAT1 and NFAT2). Substitution of the SPRIEIT sequence of NFAT with HPVIVIT, a higher-affinity version obtained by peptide selection, increases the basal calcineurin sensitivity of the protein significantly. Similarly, a major kinase for NFAT is CK1, and mutation of the CK1 docking site (FSILF to ASILA in NFAT1, FDFEF to ADAEA in NFAT2) also leads to partial nuclear localization of NFAT proteins by decreasing rephosphorylation and nuclear export. In the current analysis we compared the different hyperactivable NFAT proteins with respect to Dephosphorylation status and nuclear translocation using western blotting and immunocytochemistry. Whereas the wildtype NFAT protein was entirely localized in the cytoplasm and completely phosphorylated under resting conditions, we observed an increasing degree of nuclear translocation and Dephosphorylation for the different mutant proteins (ASILA 20%, VIVIT 30–40%, ASILA-VIVIT 50–70%). This system will allow us to study the impact of different levels of NFAT activation on the pathogenesis of lymphomas in vivo.
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the role of the transcription factor nfat in the pathogenesis of non hodgkin s lymphomas
Blood, 2006Co-Authors: Martin R. Mueller, Yoshiteru Sasaki, Sonia Sharma, Klaus RajewskyAbstract:NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon Dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT translocates to the nucleus, where it induces the transcription of a large number of genes necessary for a productive immune response. NFAT signalling has also been implicated in lymphocyte homeostasis and its deregulation has been suggested to be involved in the pathogenesis of different malignancies. A recent immunohistochemical evaluation of approximately 300 Non-Hodgkin’s Lymphoma biopsy samples showed overexpression of NFAT2 in the majority of specimens with strong nuclear translocation in certain histologic subtypes (DLBCL, Burkitt’s Lymphoma) presumably reflecting activation of the NFAT pathway as part of their pathogenesis. Other recent studies have shown that NFAT activation leads to increased expression of different cell survival factors (CD154, BLyS) in several lymphoma subtypes (DLBCL, MCL). To study the role of constitutive activation of the NFAT pathway on lymphomagenesis, we generated several hyperactivable NFAT mutants which will be used to generate transgenic mice expressing the mutant proteins from the ROSA26 locus. Here, we present the in vitro characterization of these hyperactivable NFAT proteins in cell lines and primary lymphocytes. The major docking site for calcineurin is located at the N terminus of the NFAT regulatory domain and has the consensus sequence PxIxIT (e.g. SPRIEIT in NFAT1 and NFAT2). Substitution of the SPRIEIT sequence of NFAT with HPVIVIT, a higher-affinity version obtained by peptide selection, increases the basal calcineurin sensitivity of the protein significantly. Similarly, a major kinase for NFAT is CK1, and mutation of the CK1 docking site (FSILF to ASILA in NFAT1, FDFEF to ADAEA in NFAT2) also leads to partial nuclear localization of NFAT proteins by decreasing rephosphorylation and nuclear export. In the current analysis we compared the different hyperactivable NFAT proteins with respect to Dephosphorylation status and nuclear translocation using western blotting and immunocytochemistry. Whereas the wildtype NFAT protein was entirely localized in the cytoplasm and completely phosphorylated under resting conditions, we observed an increasing degree of nuclear translocation and Dephosphorylation for the different mutant proteins (ASILA 20%, VIVIT 30–40%, ASILA-VIVIT 50–70%). This system will allow us to study the impact of different levels of NFAT activation on the pathogenesis of lymphomas in vivo.
David B. Sacks - One of the best experts on this subject based on the ideXlab platform.
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Dephosphorylation of the nuclear factor of activated t cells nfat transcription factor is regulated by an rna protein scaffold complex
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Sonia Sharma, Valentina A. Schmidt, Gregory M Findlay, Hozefa S Bandukwala, Shalini Oberdoerffer, Beate Baust, Zhigang Li, Patrick G Hogan, David B. SacksAbstract:Nuclear factor of activated T cells (NFAT) proteins are Ca2+-regulated transcription factors that control gene expression in many cell types. NFAT proteins are heavily phosphorylated and reside in the cytoplasm of resting cells; when cells are stimulated by a rise in intracellular Ca2+, NFAT proteins are dephosphorylated by the Ca2+/calmodulin-dependent phosphatase calcineurin and translocate to the nucleus to activate target gene expression. Here we show that phosphorylated NFAT1 is present in a large cytoplasmic RNA-protein scaffold complex that contains a long intergenic noncoding RNA (lincRNA), NRON [noncoding (RNA) repressor of NFAT]; a scaffold protein, IQ motif containing GTPase activating protein (IQGAP); and three NFAT kinases, casein kinase 1, glycogen synthase kinase 3, and dual specificity tyrosine phosphorylation regulated kinase. Combined knockdown of NRON and IQGAP1 increased NFAT Dephosphorylation and nuclear import exclusively after stimulation, without affecting the rate of NFAT rephosphorylation and nuclear export; and both NRON-depleted T cells and T cells from IQGAP1-deficient mice showed increased production of NFAT-dependent cytokines. Our results provide evidence that a complex of lincRNA and protein forms a scaffold for a latent transcription factor and its regulatory kinases, and support an emerging consensus that lincRNAs that bind transcriptional regulators have a similar scaffold function.