CD4-CD8 lineage commitment is regulated by a silencer element at the ThPOK transcription-factor locus.

The transcription factor ThPOK is necessary and sufficient to trigger adoption of the CD4 lymphocyte fate. Here we investigate the regulation of ThPOK expression and its subsequent control of CD4+ T cell commitment. Treatment of immature thymocytes with anti-TCR (T cell receptor) showed that TCR signals were important in ThPOK induction and that the CD4+8lo stage was the likely target of the inductive TCR signal. We identified at the ThPOK locus a key distal regulatory element (DRE) that mediated its differential expression in class I- versus II-restricted CD4+8lo thymocytes. The DRE was both necessary for suppression of ThPOK expression in class I-restricted thymocytes and sufficient for its induction in class II-restricted thymocytes. Mutagenesis analysis defined an essential 80bp core DRE sequence and its potential regulatory motifs. We propose a silencer-dependent model of lineage choice, whereby inactivation of the DRE silencer by a strong TCR signal leads to CD4 commitment, whereas continued silencer activity leads to CD8 commitment.

[1]  S. Tonegawa,et al.  CD3δ deficiency arrests development of the αβ but not the γδ T cell lineage , 1997 .

[2]  D. Littman,et al.  Evidence for a stochastic mechanism in the differentiation of mature subsets of T lymphocytes , 1993, Cell.

[3]  H. Pircher,et al.  Differentiation of CD4highCD8low coreceptor‐skewed thymocytes into mature CD8 single‐positive cells independent of MHC class I recognition , 1997, European journal of immunology.

[4]  D. Kioussis,et al.  Improved version of a human CD2 minigene based vector for T cell-specific expression in transgenic mice. , 1995, Journal of immunological methods.

[5]  C. Benoist,et al.  Role of coreceptors in positive selection and lineage commitment. , 1994, The EMBO journal.

[6]  J. Alberola-Ila,et al.  GATA-3 expression is controlled by TCR signals and regulates CD4/CD8 differentiation. , 2003, Immunity.

[7]  Y. Takahama,et al.  In Vivo Treatment of Class II MHC-Deficient Mice with Anti-TCR Antibody Restores the Generation of Circulating CD4 T Cells and Optimal Architecture of Thymic Medulla 1 , 2003, The Journal of Immunology.

[8]  S. Hedrick,et al.  A transcriptional silencer controls the developmental expression of the CD4 gene. , 1994, The EMBO journal.

[9]  D. Kioussis,et al.  Inducible expression of a p56Lck transgene reveals a central role for Lck in the differentiation of CD4 SP thymocytes. , 2000, Immunity.

[10]  Michael A. Bookman,et al.  The CD4 and CD8 T cell surface antigens are associated with the internal membrane tyrosine-protein kinase p56 lck , 1988, Cell.

[11]  S. Pai,et al.  Critical roles for transcription factor GATA-3 in thymocyte development. , 2003, Immunity.

[12]  I. Weissman,et al.  T cell receptor-mediated negative selection of autoreactive T lymphocyte precursors occurs after commitment to the CD4 or CD8 lineages , 1990, The Journal of experimental medicine.

[13]  J. Alberola-Ila,et al.  The Ras/MAPK cascade and the control of positive selection , 2003, Immunological reviews.

[14]  R. Germain,et al.  Unexpectedly complex regulation of CD4/CD8 coreceptor expression supports a revised model for CD4+CD8+ thymocyte differentiation. , 1996, Immunity.

[15]  D. Wiest,et al.  Regulation of lineage commitment distinct from positive selection. , 1999, Science.

[16]  Xiaolong Liu,et al.  Duration of TCR signaling controls CD4-CD8 lineage differentiation in vivo , 2004, Nature Immunology.

[17]  D. Kappes,et al.  Role of the transcription factor Th‐POK in CD4:CD8 lineage commitment , 2006, Immunological reviews.

[18]  W. Fanslow,et al.  Constitutive CD8 expression allows inefficient maturation of CD4+ helper T cells in class II major histocompatibility complex mutant mice , 1994, The Journal of experimental medicine.

[19]  R. E. Tillman,et al.  The role of the Runx transcription factors in thymocyte differentiation and in homeostasis of naive T cells , 2007, The Journal of experimental medicine.

[20]  M. A. Basson,et al.  Activation of the extracellular signal-related kinase/mitogen-activated protein kinase pathway discriminates CD4 versus CD8 lineage commitment in the thymus. , 1999, Journal of immunology.

[21]  T. Möröy,et al.  Runx3 regulates integrin alpha E/CD103 and CD4 expression during development of CD4-/CD8+ T cells. , 2005, Journal of immunology.

[22]  N. Killeen,et al.  MHC class II-specific T cells can develop in the CD8 lineage when CD4 is absent. , 1996, Immunity.

[23]  D. Littman,et al.  Differential Requirements for Runx Proteins in CD4 Repression and Epigenetic Silencing during T Lymphocyte Development , 2002, Cell.

[24]  F. Grosveld,et al.  Enforced Expression of GATA-3 During T Cell Development Inhibits Maturation of CD8 Single-Positive Cells and Induces Thymic Lymphoma in Transgenic Mice1 , 2001, The Journal of Immunology.

[25]  K. Ravichandran,et al.  Evidence for differential intracellular signaling via CD4 and CD8 molecules , 1994, The Journal of experimental medicine.

[26]  Martin S. Taylor,et al.  Genome-wide analysis of mammalian promoter architecture and evolution , 2006, Nature Genetics.

[27]  R. Hardy,et al.  HD mice: a novel mouse mutant with a specific defect in the generation of CD4(+) T cells. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[28]  C. Marshall,et al.  The influence of the MAPK pathway on T cell lineage commitment. , 1997, Immunity.

[29]  A. Singer,et al.  Asymmetric signaling requirements for thymocyte commitment to the CD4+ versus CD8+ T cell lineages: a new perspective on thymic commitment and selection. , 1995, Immunity.

[30]  C. Benoist,et al.  Another view of the selective model of thymocyte selection , 1993, Cell.

[31]  W. Heath,et al.  Intermediate steps in positive selection: differentiation of CD4+8int TCRint thymocytes into CD4-8+TCRhi thymocytes , 1995, The Journal of experimental medicine.

[32]  A. Singer,et al.  Coreceptor reversal in the thymus: signaled CD4+8+ thymocytes initially terminate CD8 transcription even when differentiating into CD8+ T cells. , 2000, Immunity.

[33]  Dustin E. Schones,et al.  High-Resolution Profiling of Histone Methylations in the Human Genome , 2007, Cell.

[34]  D. Kioussis,et al.  Thymic selection in CD8 transgenic mice supports an instructive model for commitment to a CD4 or CD8 lineage , 1991, Cell.

[35]  H. Kishi,et al.  Development of the CD4 and CD8 lineage of T cells: instruction versus selection. , 1991, The EMBO journal.

[36]  J. Pouysségur,et al.  The role of erk1 and erk2 in multiple stages of T cell development. , 2005, Immunity.

[37]  C. Benoist,et al.  Visualization of CD4/CD8 T Cell Commitment , 1998, The Journal of experimental medicine.

[38]  S. Habu,et al.  Dual functions of Runx proteins for reactivating CD8 and silencing CD4 at the commitment process into CD8 thymocytes. , 2005, Immunity.

[39]  A. Tyznik,et al.  The CD8 Population in CD4-deficient Mice Is Heavily Contaminated with MHC Class II–restricted T Cells , 2004, The Journal of experimental medicine.

[40]  D. Littman,et al.  A lineage-specific transcriptional silencer regulates CD4 gene expression during T lymphocyte development , 1994, Cell.

[41]  A. W. Harris,et al.  Intermediate steps in thymic positive selection. Generation of CD4-8+ T cells in culture from CD4+8+, CD4int8+, and CD4+8int thymocytes with up-regulated levels of TCR-CD3. , 1995, Journal of immunology.

[42]  M. Petter,et al.  Morpholino Antisense Oligonucleotide-Mediated Gene Knockdown During Thymocyte Development Reveals Role for Runx3 Transcription Factor in CD4 Silencing During Development of CD4−/CD8+ Thymocytes 1 , 2003, The Journal of Immunology.

[43]  D. Littman,et al.  Helper T-cell development in the absence of CD4-p56 Ick association , 1993, Nature.

[44]  T. Möröy,et al.  Runx3 Regulates Integrin αE/CD103 and CD4 Expression during Development of CD4−/CD8+ T Cells1 , 2005, The Journal of Immunology.

[45]  J. Alberola-Ila,et al.  Lck activity controls CD4/CD8 T cell lineage commitment. , 2000, Immunity.

[46]  Kristin A. Hogquist,et al.  T cell receptor antagonist peptides induce positive selection , 1994, Cell.

[47]  Yi Zhang,et al.  The zinc finger transcription factor Th-POK regulates CD4 versus CD8 T-cell lineage commitment , 2005, Nature.

[48]  Xiaolong Liu,et al.  The zinc finger protein cKrox directs CD4 lineage differentiation during intrathymic T cell positive selection , 2005, Nature Immunology.

[49]  A. Singer,et al.  CD4/CD8 coreceptors in thymocyte development, selection, and lineage commitment: analysis of the CD4/CD8 lineage decision. , 2004, Advances in immunology.