Key points are not available for this paper at this time.
Signals transduced by the T cell antigen receptor (TCR) regulate developmental transitions in the thymus and also mediate the immunologic activation of mature, peripheral T cells. In both cases TCR stimulation leads to the assembly of the NFAT transcription complex as a result of the calcium-dependent nuclear translocation of cytosolic subunits, NFATc, and the Ras/protein kinase C-dependent induction of a nuclear subunit, NFATn. To further understand the diverse roles of antigen receptor signaling throughout T cell development, we have identified a new NFATc family member, NFATc3, that is expressed at highest levels in the thymus. NFATc3 is the product of a gene on murine chromosome 8 that is not linked to the other NFATc genes. NFATc3, like other NFATc family members, contains a conserved rel similarity domain, and also defines a region conserved among NFATc family members, the SP repeat region, characterized by the repeated motif SPxxSPxxSPrxsxx(D/E)(D/E)swl. NFATc3 activates NFAT site-dependent transcription when overexpressed, yet exhibits a pattern of DNA site specificity distinct from other NFATc proteins. Additionally, thymic NFATc3 undergoes modifications in response to agents that mimic T cell receptor signaling, including a decrease in apparent molecular mass upon elevation of intracellular calcium that is inhibited by the immunosuppressant FK506. Given the preferential expression of NFATc3 in the thymus, NFATc family members may regulate distinct subsets of genes during T cell development. Signals transduced by the T cell antigen receptor (TCR) regulate developmental transitions in the thymus and also mediate the immunologic activation of mature, peripheral T cells. In both cases TCR stimulation leads to the assembly of the NFAT transcription complex as a result of the calcium-dependent nuclear translocation of cytosolic subunits, NFATc, and the Ras/protein kinase C-dependent induction of a nuclear subunit, NFATn. To further understand the diverse roles of antigen receptor signaling throughout T cell development, we have identified a new NFATc family member, NFATc3, that is expressed at highest levels in the thymus. NFATc3 is the product of a gene on murine chromosome 8 that is not linked to the other NFATc genes. NFATc3, like other NFATc family members, contains a conserved rel similarity domain, and also defines a region conserved among NFATc family members, the SP repeat region, characterized by the repeated motif SPxxSPxxSPrxsxx(D/E)(D/E)swl. NFATc3 activates NFAT site-dependent transcription when overexpressed, yet exhibits a pattern of DNA site specificity distinct from other NFATc proteins. Additionally, thymic NFATc3 undergoes modifications in response to agents that mimic T cell receptor signaling, including a decrease in apparent molecular mass upon elevation of intracellular calcium that is inhibited by the immunosuppressant FK506. Given the preferential expression of NFATc3 in the thymus, NFATc family members may regulate distinct subsets of genes during T cell development. INTRODUCTIONThe antigen receptor of T lymphocytes subserves diverse functions during development. In the thymus, signals from the antigen receptor rescue from death those cells that have low avidity receptors for self-antigens bound to major histocompatability complex molecules (positive selection), whereas high avidity self-antigens induce programmed cell death (negative selection)(1Ashton-Rickardt P.G. Tonegawa S. Immunol. Today. 1994; 15: 362-366Abstract Full Text PDF PubMed Scopus (17) Google Scholar). In mature, peripheral T cells, interaction with foreign antigen leads to immunologic activation. In each case characteristic sets of genes are activated or repressed by signals emanating from the antigen receptor. For example, antigen receptor-induced repression of the RAG-1 and RAG-2 genes (2Turka L.A. Schatz D.G. Oettinger M.A. Chun J.J. Gorka C. Lee K. McCormack W.T. Thompson C.B. Science. 1991; 253: 778-781Crossref PubMed Scopus (223) Google Scholar) and activation of the CD69 gene (3Yamashita I. Nagata T. Tada T. Nakayama T. Int. Immunol. 1993; 5: 1139-1150Crossref PubMed Scopus (197) Google Scholar) are hallmarks of thymic selection. In mature T cells, antigen receptor-induced expression of growth factor genes such as IL-2 1The abbreviations used are: ILinterleukinNFATnuclear factor of activated T cellsNFATccytosolic component of NFATPMAphorbol 12-myristate 13-acetateTCRT cell antigen receptorARREantigen receptor response elementGM-CSFgranulocyte-macrophage colony-stimulating factorTNFtumor necrosis factorPCRpolymerase chain reactionbpbase pair(s)PIPES1,4-piperazinediethanesulfonic acidRSDrel similarity domain(s). and genes that encode cell-cell interaction molecules, such as the CD40 ligand, are essential for immunologic function and proliferation. How these diverse cell fates and functions are initiated by the T cell antigen receptor (TCR) is not understood, but likely involve the use of distinct antigen receptor response elements to activate genes essential for specific developmental transitions.T cell antigen receptor response elements (ARREs) were initially described in the IL-2 gene of mature T cells(4Durand D.B. Shaw J.P. Bush PubMed Scopus Google Scholar). complex that to of these nuclear factor of activated T cells J.P. D.B. J.J. Science. PubMed Scopus Google to and calcium-dependent signals initiated by the antigen receptor the assembly of cytosolic and nuclear NFATc is in the of lymphocytes in a and to the of T cell 1991; PubMed Scopus Google Scholar). translocation as as NFAT complex and NFAT site-dependent is and and by the and 1991; PubMed Scopus Google D.B. Science. PubMed Scopus Google PubMed Scopus Google PubMed Scopus Google Scholar). is of T cell activation by a Ras/protein kinase C-dependent and by high levels of 1991; PubMed Scopus Google J.P. 1993; Full Text PDF PubMed Google P.G. T. 1993; PubMed Scopus Google Scholar). In to the NFAT site the IL-2 gene NFAT DNA have identified in the of genes that are upon antigen receptor activation in a including M.A. S. 1993; PubMed Scopus Google 1993; PubMed Scopus Google I. S. K. 1994; PubMed Scopus Google P.G. 1994; PubMed Scopus Google P.G. 1993; PubMed Scopus Google D.G. I. 1994; PubMed Scopus Google Immunol. 1994; PubMed Scopus Google and Immunol. 1993; PubMed Scopus Google Scholar). 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Full Text Full Text PDF PubMed Scopus Google region are of of by in NFATc to of conserved and likely those that are in the of the DNA and those that in to the in DNA of a of the NFATc family further of region of the SP repeat region, and is of a SP repeat motif repeated SP repeat region are not conserved in to each but also to the that is the of repeated a motif that may a the function of the SP repeat region the that each of the NFATc family a calcium-dependent in molecular mass that is by agents that that region may the site of of SP repeat the SP repeat region that a for may a of the function of NFATc proteins. a for modifications function to a for NFATc activation such that low levels of a that of intracellular calcium to activate a for the activation of that for the complex factor and with response factor to regulate transcription from response 1994; PubMed Scopus Google Scholar). the of SP repeat region may for specific of the DNA specificity of NFATc family members by distinct in the specificity of the NFATc for or antigen receptor response elements in T cell activation genes. the in DNA specificity may in the of of each of the NFATc family members with a specific DNA that the in DNA specificity may in the specificity of interaction with other that the NFAT that may the nuclear NFAT that NFATc3 may not a to the NFAT DNA complex at the IL-2 in of cells from the thymus, and NFATc3 may to the of as yet genes in response to T cell antigen receptor Given the of the agents and in T cell development, such genes may a in developmental in the in the molecular mass of NFATc3 upon stimulation with agents that intracellular calcium or activate kinase that NFATc3, like J.P. L.A. 1994; PubMed Scopus Google is the of distinct signaling by of by intracellular calcium that NFATc3 may or the as is that is the of the complex and I. 1991; Full Text PDF PubMed Scopus Google Scholar). calcium-dependent decrease in the apparent mass of NFATc3 is with a by P.G. T. 1993; PubMed Scopus Google Scholar) or by a such as S. S. 1994; PubMed Scopus Google Scholar). site of is likely the SP repeat region, as is the region of similarity among NFATc other the DNA gene by cell and in to chromosome 8 a region of conserved with the of chromosome have to chromosome and to chromosome of with and L.A. PubMed Scopus Google Scholar). that the genes the NFATc family are not in the in the of a is characterized by at in to of described NFATc3 to expressed in a of NFATc3 expression in not a for NFATc3 in and in the of the a that NFATc3 is expressed at high levels in the thymus and is of yet not to to that may a in the transcription of genes with distinct from those that have that such genes by NFATc3 are in T cell in the thymus is by the that thymic NFATc3 undergoes modifications in response to the intracellular signals that regulate in of the for NFATc3 and nuclear of NFATc3 essential to understand in the complex development. INTRODUCTIONThe antigen receptor of T lymphocytes subserves diverse functions during development. In the thymus, signals from the antigen receptor rescue from death those cells that have low avidity receptors for self-antigens bound to major histocompatability complex molecules (positive selection), whereas high avidity self-antigens induce programmed cell death (negative selection)(1Ashton-Rickardt P.G. Tonegawa S. Immunol. Today. 1994; 15: 362-366Abstract Full Text PDF PubMed Scopus (17) Google Scholar). In mature, peripheral T cells, interaction with foreign antigen leads to immunologic activation. In each case characteristic sets of genes are activated or repressed by signals emanating from the antigen receptor. For example, antigen receptor-induced repression of the RAG-1 and RAG-2 genes (2Turka L.A. Schatz D.G. Oettinger M.A. Chun J.J. Gorka C. Lee K. McCormack W.T. Thompson C.B. Science. 1991; 253: 778-781Crossref PubMed Scopus (223) Google Scholar) and activation of the CD69 gene (3Yamashita I. Nagata T. Tada T. Nakayama T. Int. Immunol. 1993; 5: 1139-1150Crossref PubMed Scopus (197) Google Scholar) are hallmarks of thymic selection. In mature T cells, antigen receptor-induced expression of growth factor genes such as IL-2 1The abbreviations used are: ILinterleukinNFATnuclear factor of activated T cellsNFATccytosolic component of NFATPMAphorbol 12-myristate 13-acetateTCRT cell antigen receptorARREantigen receptor response elementGM-CSFgranulocyte-macrophage colony-stimulating factorTNFtumor necrosis factorPCRpolymerase chain reactionbpbase pair(s)PIPES1,4-piperazinediethanesulfonic acidRSDrel similarity domain(s). and genes that encode cell-cell interaction molecules, such as the CD40 ligand, are essential for immunologic function and proliferation. How these diverse cell fates and functions are initiated by the T cell antigen receptor (TCR) is not understood, but likely involve the use of distinct antigen receptor response elements to activate genes essential for specific developmental transitions.T cell antigen receptor response elements (ARREs) were initially described in the IL-2 gene of mature T cells(4Durand D.B. Shaw J.P. Bush PubMed Scopus Google Scholar). complex that to of these nuclear factor of activated T cells J.P. D.B. J.J. Science. PubMed Scopus Google to and calcium-dependent signals initiated by the antigen receptor the assembly of cytosolic and nuclear NFATc is in the of lymphocytes in a and to the of T cell 1991; PubMed Scopus Google Scholar). translocation as as NFAT complex and NFAT site-dependent is and and by the and 1991; PubMed Scopus Google D.B. Science. PubMed Scopus Google PubMed Scopus Google PubMed Scopus Google Scholar). is of T cell activation by a Ras/protein kinase C-dependent and by high levels of 1991; PubMed Scopus Google J.P. 1993; Full Text PDF PubMed Google P.G. T. 1993; PubMed Scopus Google Scholar). In to the NFAT site the IL-2 gene NFAT DNA have identified in the of genes that are upon antigen receptor activation in a including M.A. S. 1993; PubMed Scopus Google 1993; PubMed Scopus Google I. S. K. 1994; PubMed Scopus Google P.G. 1994; PubMed Scopus Google P.G. 1993; PubMed Scopus Google D.G. I. 1994; PubMed Scopus Google Immunol. 1994; PubMed Scopus Google and Immunol. 1993; PubMed Scopus Google Scholar). NFAT a transcription factor complex that signals transduced by the TCR the use of that are the of distinct signaling to in the induction of genes in mature T NFAT may also in T cell in the thymus. have not for TCR signaling in the thymus, the of to induce NFAT DNA to the IL-2 to is upon that in NFAT is in cells, in and in the J.P. Immunol. Google 1993; PubMed Scopus Google Scholar). for NFAT in thymic is also by the that or and transcription by the NFAT 1991; PubMed Scopus Google PubMed Scopus Google PubMed Scopus Google the of the and of Science. PubMed Scopus Google PubMed Scopus Google Scholar). a of a for the NFAT transcription factor complex in in the thymus, is of the specific by is in to a of of the molecular of the NFAT complex in and the of of for signaling by the T and molecular of the or cytosolic component of NFAT in the of distinct P.G. C. T. Science. 1993; PubMed Scopus Google Scholar) and J.P. L.A. 1994; PubMed Scopus Google both of encode that are of to NFAT DNA and are in the NFAT a conserved region of similarity to the rel of transcription and to a distinct family or of transcription J.P. L.A. 1994; PubMed Scopus Google Scholar). family also characterized by other by NFATc and such as function as of calcium-dependent is of these we have a of by the L.A. PubMed Scopus Google in the family of or transcription factor genes is family members are cytosolic as described and to the the of the NFAT 1991; PubMed Scopus Google and each of family is and are used to the NFATc and and to the murine we to the or as To further the of the NFATc family of transcription in and T cell development, a from to 1994; PubMed Scopus Google Scholar) for NFATc family that a NFATc family member, of that NFATc3 is expressed in thymus, and and that NFATc3 exhibits DNA specificity distinct from that of other NFATc family thymic NFATc3 undergoes in apparent molecular mass in response to in intracellular calcium that are by the immunosuppressant that NFATc3 is by in a to the other NFATc family of the molecular of NFATc and a of the of the NFATc family of transcription in thymic and
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