scholarly journals A role for proapoptotic Bax and Bak in T-cell differentiation and transformation

Blood ◽  
2010 ◽  
Vol 116 (24) ◽  
pp. 5237-5246 ◽  
Author(s):  
Subhrajit Biswas ◽  
Qiong Shi ◽  
Lauren Matise ◽  
Susan Cleveland ◽  
Utpal Dave ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
Progenitor Cells ◽  
T Cell Development ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
T Cell Differentiation ◽  
Intrinsic Pathway ◽  
Deficient Mice

Abstract Proapoptotic Bax and Bak are the key B-cell lymphoma-2 family members mediating apoptosis through the intrinsic pathway. Cells doubly deficient for Bax and Bak are profoundly resistant to apoptotic stimuli originating from multiple stimuli. Here we describe mice in which Bax and Bak have been deleted specifically in T-cells using Lck-Cre. In these T cell–specific BaxBak-deficient mice, early T-cell progenitors accumulate in the thymus, with relative depletion of more mature T cells. In addition, bone marrow progenitor cells fail to progress to the double positive stage when cultured on OP9 stromal cells expressing the Notch ligand Delta-like 1, consistent with a critical role for Bax and Bak in early T-cell development. Over time, T cell–specific BaxBak-deficient mice progress to an aggressive T-cell lymphoblastic leukemia/lymphoma. Interestingly, quantitative real-time polymerase chain reaction analysis of BaxBak-deficient T-cell lymphomas does not display amplification of the Notch signal transduction pathway, commonly activated in T-cell leukemia in both mouse and man. Bax and Bak, key regulators of the intrinsic pathway of apoptosis, are thus required to prevent T-cell malignancy, and for normal T-cell differentiation, regulating early T-cell development at the stage of early T-lineage progenitor cells.

scholarly journals B cell adaptor for PI3-kinase (BCAP) modulates CD8+ effector and memory T cell differentiation

2018 ◽  
Vol 215 (9) ◽  
pp. 2429-2443 ◽  
Author(s):  
Mark D. Singh ◽  
Minjian Ni ◽  
Jenna M. Sullivan ◽  
Jessica A. Hamerman ◽  
Daniel J. Campbell
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
B Cell ◽  
Cd8 T Cells ◽  
T Cell Development ◽  
Cell Development ◽  
T Cell Differentiation ◽  
Pi3k Signaling ◽  
Memory T Cell

CD8+ T cells respond to signals via the T cell receptor (TCR), costimulatory molecules, and immunoregulatory cytokines by developing into diverse populations of effector and memory cells. The relative strength of phosphoinositide 3-kinase (PI3K) signaling early in the T cell response can dramatically influence downstream effector and memory T cell differentiation. We show that initial PI3K signaling during T cell activation results in up-regulation of the signaling scaffold B cell adaptor for PI3K (BCAP), which further potentiates PI3K signaling and promotes the accumulation of CD8+ T cells with a terminally differentiated effector phenotype. Accordingly, BCAP-deficient CD8+ T cells have attenuated clonal expansion and altered effector and memory T cell development following infection with Listeria monocytogenes. Thus, induction of BCAP serves as a positive feedback circuit to enhance PI3K signaling in activated CD8+ T cells, thereby acting as a molecular checkpoint regulating effector and memory T cell development.

scholarly journals Analysis of Thymocyte Development Reveals That the Gtpase Rhoa Is a Positive Regulator of T Cell Receptor Responses in Vivo

2001 ◽  
Vol 194 (7) ◽  
pp. 903-914 ◽  
Author(s):  
Isabelle Corre ◽  
Manuel Gomez ◽  
Susina Vielkind ◽  
Doreen A. Cantrell
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Development ◽  
Cell Receptor ◽  
Cell Development ◽  
T Cell Differentiation ◽  
Thymocyte Development

Loss of function of the guanine nucleotide binding protein RhoA blocks pre-T cell differentiation and survival indicating that this GTPase is a critical signaling molecule during early thymocyte development. Previous work has shown that the Rho family GTPase Rac-1 can initiate changes in actin dynamics necessary and sufficient for pre-T cell development. The present data now show that Rac-1 actions in pre-T cells require Rho function but that RhoA cannot substitute for Rac-1 and induce the actin cytoskeletal changes necessary for pre-T cell development. Activation of Rho is thus not sufficient to induce pre-T cell differentiation or survival in the absence of the pre-T cell receptor (TCR). The failure of RhoA activation to impact on pre-TCR–mediated signaling was in marked contrast to its actions on T cell responses mediated by the mature TCR α/β complex. Cells expressing active RhoA were thus hyperresponsive in the context of TCR-induced proliferation in vitro and in vivo showed augmented positive selection of thymocytes expressing defined TCR complexes. This reveals that RhoA function is not only important for pre-T cells but also plays a role in determining the fate of mature T cells.

Constitutive Expression of MEF2C, LYL1, or LMO2 in CD34+ HSCs Blocks the in Vitro Differentiation before the T-Cell Commitment Point and Could be Oncogenic in Early T-Cell Progenitor ALL

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2423-2423
Author(s):  
Kirsten Canté-Barrett ◽  
Rui D Mendes ◽  
Wilco K Smits ◽  
Rob Pieters ◽  
Jules PP Meijerink
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
T Cell Differentiation ◽  
Cell Commitment

Abstract Background: T-cell development in the thymus is a complex process that depends on sequential transcriptional and epigenetic events that induce T-cell lineage commitment and simultaneously suppress alternative cell fates. In T-cell acute lymphoblastic leukemia (T-ALL), aberrantly expressed oncogenes result in the arrest of developing thymocytes, which can lead to the acquisition of secondary mutations, uncontrolled proliferation and disease progression. MEF2C is often expressed as a result of chromosomal rearrangements in immature, early T-cell progenitor ALL (ETP-ALL), but is also expressed in normal thymocyte progenitors before T-cell commitment (in the ETP stage). As the only hematopoietic lineage, thymocytes that have passed the T-cell commitment checkpoint (as well as mature T-cells) do no longer express MEF2C. Aims: We aimed to investigate the effect of constitutive MEF2C expression on early T-cell development. OP9-DL1 co-cultures have been most useful for mimicking in vitro T-cell development starting with hematopoietic stem cells (HSCs) derived from human cord blood or bone marrow. We also aimed to investigate the impact of MEF2C in comparison to LYL1 and LMO2; two T-ALL oncogenes also highly expressed at the ETP stage. Methods: We have utilized the OP9-DL1 in vitro co-culture system to gradually differentiate CD34+ HSCs from umbilical cord blood into the T-cell lineage. HSCs in this co-culture will recapitulate in vivo T-cell development as measured by incremental acquisition of surface markers CD7, CD5, CD1a, and reach the CD4, CD8 double-positive (DP) stage. We generated gene expression profiles of 11 subsequent in vitro stages of differentiation to help us match them to in vivo development stages. We investigated in vitro T-cell differentiation of HSCs after lentiviral transduction with MEF2C or control vectors, as well as with other transcriptional regulators LYL1 and LMO2 that are expressed at the ETP stage. Results: The major change in gene expression of subsequent early T-cell differentiation stages defines two distinct T-cell differentiation clusters that correlate with in vivo pre- and post-T-cell commitment profiles. We found that T-cell commitment occurs in CD7+ CD5+ cells before the acquisition of CD1a surface expression. Expression of control vectors in HSCs does not affect the in vitro T-cell differentiation, but MEF2C expression blocks differentiation into the direction of T-cells as measured by the failure of most cells to acquire CD7 as the first marker. Instead, with increased passage number cells gradually lose CD34 expression and eventually disappear from the co-culture. Similar effects were observed for the expression of LYL1 and LMO2; LYL1 expression arrests the cells at the most immature CD7+ ETP stage and prevents the transition towards CD7+ CD5+ cells, whereas LMO2 expressing cells reach the CD7+ CD5+ stage but fail to acquire CD1a as a marker of T-cell commitment. Summary/Conclusion: The gene expression profiles of 11 human in vitro T-cell differentiation subsets has enabled us to pinpoint T-cell commitment to a stage in which cells have acquired CD7 and CD5, just prior to the acquisition of CD1a. MEF2C, LYL1, and LMO2, expressed in ETP-ALL as well as in normal thymocyte progenitors, do not allow the transition to T-cell commitment when constitutively expressed. These proteins each result in the arrest of in vitro differentiating T-cells at different ETP stages, all before the T-cell commitment as marked by CD1a expression. Constitutive expression of MEF2C, LYL1, or LMO2 in very early thymocyte progenitors is incompatible with development into and beyond the T-cell commitment checkpoint and these proteins could therefore play important roles in the pathogenesis of ETP-ALL. Disclosures No relevant conflicts of interest to declare.

scholarly journals Inactivation of c-Cbl Reverses Neonatal Lethality and T Cell Developmental Arrest of SLP-76–deficient Mice

2004 ◽  
Vol 200 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Y. Jeffrey Chiang ◽  
Connie L. Sommers ◽  
Martha S. Jordan ◽  
Hua Gu ◽  
Lawrence E. Samelson ◽  
...  
Keyword(s):  
Signal Transduction ◽  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Adaptor Protein ◽  
Premature Death ◽  
Cell Receptor ◽  
Cell Development ◽  
Neonatal Lethality ◽  
Deficient Mice

c-Cbl is an adaptor protein that negatively regulates signal transduction events involved in thymic-positive selection. To further characterize the function of c-Cbl in T cell development, we analyzed the effect of c-Cbl inactivation in mice deficient in the scaffolding molecule SLP-76. SLP-76–deficient mice show a high frequency of neonatal lethality; and in surviving mice, T cell development is blocked at the DN3 stage. Inactivation of c-cbl completely reversed the neonatal lethality seen in SLP-76–deficient mice and partially reversed the T cell development arrest in these mice. SLP-76−/− Cbl−/− mice exhibited marked expansion of polarized T helper type (Th)1 and Th2 cell peripheral CD4+ T cells, lymphoid infiltrates of parenchymal organs, and premature death. This rescue of T cell development is T cell receptor dependent because it does not occur in recombination activating gene 2−/− SLP-76−/− Cbl−/− triple knockout mice. Analysis of the signal transduction properties of SLP-76−/− Cbl−/− T cells reveals a novel SLP-76– and linker for activation of T cells–independent pathway of extracellular signal–regulated kinase activation, which is normally down-regulated by c-Cbl.

Opposing Effects of Toll-Like Receptor Ligands and Ascorbic Acid On T and Natural Killer Cell Development From Lymphoid Progenitor Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1491-1491 ◽  
Author(s):  
Birgitta Mitchell ◽  
Maritza Gonzalez ◽  
Jared Manning ◽  
Gerald J Spangrude
Keyword(s):  
Ascorbic Acid ◽  
Cell Differentiation ◽  
T Cell ◽  
Progenitor Cells ◽  
Nk Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
T Cell Differentiation ◽  
Nk Cell Differentiation

Abstract Abstract 1491 Poster Board I-514 Introduction: A complete understanding of lymphocyte development, particularly factors driving T and natural killer (NK) cell differentiation from progenitor cells, remains an elusive goal in medicine. T and NK cells are key regulators in the defense against infections and malignancies and play a direct causative role in autoimmune diseases and graft-versus-host disease. The OP9-DL1 stromal line is an important tool in the in vitro study of lymphocyte development. Lymphocyte progenitors (KLS,Thy1.1-) harvested from adult murine bone marrow and seeded on this stromal line can be followed through stages of maturation by immunophenotyping. We observed that addition of stem cell factor (SCF), contaminated with lipopolysaccharide (LPS) through its production in E. coli, was particularly effective at promoting NK cell development in the OP9-DL1 culture system. Toll-like receptors, an important component of anti-microbial defense by the innate immune response, recognize LPS and other microbial products. Toll-like receptor ligands (TLR-L) have been shown to enhance NK cell proliferation, however an effect on NK cell differentiation from progenitor cells has not been established. A separate set of experiments led us to hypothesize that ascorbic acid (vitamin C) promotes T cell differentiation. We therefore designed experiments to evaluate the differential effects of TLR-L and ascorbic acid on NK and T cell development from lymphoid progenitors co-cultured with OP9-DL1 stromal cells. Methods: Lymphocyte progenitor cells (KLS,Thy1.1-) were sorted from adult mouse bone marrow and 1000-2000 progenitor cells were seeded per well in a 24 well plate coated with OP9-DL1 stroma. Cultures were supplemented with IL-7 (5 ng/ml), Flt3 ligand (5 ng/ml), and SCF (100 ng/ml) plus one of 5 different TLR-L (TLR1/2, TLR3, TLR4, TLR5, and a crude LPS preparation that likely contains a number of TLR-L), with or without addition of a stabilized form of ascorbic acid. Cells were passaged, counted and re-seeded with fresh media and supplements twice a week over a 30-day period. Immunophenotype and viability were evaluated by flow cytometry. Markers for T cell development included CD44, CD25, CD3, CD4, CD8, T cell receptor beta chain and T cell receptor gamma-delta chains. NK cells were evaluated for the presence of NKp46, NK1.1, and DX5. Results: We observed robust cell expansion, inhibited somewhat by addition of ascorbic acid. The inhibitory effect of ascorbate on expansion was most pronounced in the culture condition lacking TLR-L. T cell differentiation was markedly advanced by the addition of ascorbic acid in the absence of TLR-L, with the majority of cells co-expressing CD4/CD8 and TCRB/CD3. The addition of different TLR-Ls inhibited T cell differentiation, and this inhibition was partially rescued by addition of ascorbic acid. NK cell differentiation, defined as co-expression of NKp46 and NK1.1, was two to three-fold greater with the addition of TLR1/2, TLR4, TLR5, and crude LPS compared to cultures lacking TLR-L addition. In each of these conditions, NK cell differentiation was markedly inhibited by addition of ascorbic acid. Conclusions: Our data supports the hypothesis that both T and NK cell progenitors require Notch signaling for differentiation. In our in vitro model, differentiation of one lineage at the expense of the other can be manipulated with addition of TLR-L or ascorbic acid. Addition of bacterial TLR-L promotes NK cell differentiation at the expense of T cell differentiation; an effect that is partially overcome with the addition of ascorbic acid. The addition of ascorbic acid promotes robust T cell differentiation, and inhibits significant NK cell differentiation in all conditions. The ability of ascorbic acid to promote T cell differentiation appears to dominate over TLR-L promotion of NK lineage differentiation. Further work will include microarray to evaluate these effects at a genetic level. These findings will contribute to our understanding of the immune response under normal and pathologic conditions, and further a model both for study and ex vivo expansion of immune cells for therapeutic use. Disclosures: No relevant conflicts of interest to declare.

scholarly journals In vitro T lymphopoiesis of human and rhesus CD34+ progenitor cells

Blood ◽  
1996 ◽  
Vol 87 (10) ◽  
pp. 4040-4048 ◽  
Author(s):  
M Rosenzweig ◽  
DF Marks ◽  
H Zhu ◽  
D Hempel ◽  
KG Mansfield ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
T Lymphocytes ◽  
Progenitor Cells ◽  
T Cell Differentiation ◽  
Hematopoietic Stem ◽  
Human Cd34 ◽  
Cd34 Cells

Differentiation of hematopoietic progenitor cells into T lymphocytes generally occurs in the unique environment of the thymus, a feature that has hindered efforts to model this process in the laboratory. We now report that thymic stromal cultures from rhesus macaques can support T-cell differentiation of human or rhesus CD34+ progenitor cells. Culture of rhesus or human CD34+ bone marrow-derived cells depleted of CD34+ lymphocytes on rhesus thymic stromal monolayers yielded CD3+CD4+CD8+, CD3+CD4+CD8-, and CD3+CD4-CD8+ cells after 10 to 14 days. In addition to classical T lymphocytes, a discrete population of CD3+CD8loCD16+CD56+ cells was detected after 14 days in cultures inoculated with rhesus CD34+ cells. CD3+ T cells arising from these cultures were not derived from contaminating T cells present in the CD34+ cells used to inoculate thymic stromal monolayers or from the thymic monolayers, as shown by labeling of cells with the lipophilic membrane dye PKH26. Expression of the recombinase activation gene RAG- 2, which is selectively expressed in developing lymphocytes, was detectable in thymic cultures inoculated with CD34+ cells but not in CD34+ cells before thymic culture or in thymic stromal monolayers alone. Reverse transcriptase-polymerase chain reaction analysis of T cells derived from thymic stromal cultures of rhesus and human CD34+ cells showed a polyclonal T-cell receptor repertoire. T-cell progeny derived from rhesus CD34+ cells cultured on thymic stroma supported vigorous simian immunodeficiency virus replication in the absence of exogenous mitogenic stimuli. Rhesus thymic stromal cultures provide a convenient means to analyze T-cell differentiation in vitro and may be useful as a model of hematopoietic stem cell therapy for diseases of T cells, including acquired immunodeficiency syndrome.

scholarly journals Microbiota Metabolite Butyrate Differentially Regulates Th1 and Th17 Cells’ Differentiation and Function in Induction of Colitis

2019 ◽  
Vol 25 (9) ◽  
pp. 1450-1461 ◽  
Author(s):  
Liang Chen ◽  
Mingming Sun ◽  
Wei Wu ◽  
Wenjing Yang ◽  
Xiangsheng Huang ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
Gut Microbiota ◽  
Th17 Cell ◽  
Cell Development ◽  
Cell Polarization ◽  
T Cell Differentiation ◽  
Th1 Cell ◽  
And Function

Abstract Background How the gut microbiota regulates intestinal homeostasis is not completely clear. Gut microbiota metabolite short-chain fatty acids (SCFAs) have been reported to regulate T-cell differentiation. However, the mechanisms underlying SCFA regulation of T-cell differentiation and function remain to be investigated. Methods CBir1, an immunodominant microbiota antigen, transgenic T cells were treated with butyrate under various T-cell polarization conditions to investigate butyrate regulation of T-cell differentiation and the mechanism involved. Transfer of butyrate-treated CBir T cells into Rag1-/- mice was performed to study the in vivo role of such T cells in inducing colitis. Results Although butyrate promoted Th1 cell development by promoting IFN-γ and T-bet expression, it inhibited Th17 cell development by suppressing IL-17, Rorα, and Rorγt expression. Interestingly, butyrate upregulated IL-10 production in T cells both under Th1 and Th17 cell conditions. Furthermore, butyrate induced T-cell B-lymphocyte-induced maturation protein 1 (Blimp1) expression, and deficiency of Blimp1 in T cells impaired the butyrate upregulation of IL-10 production, indicating that butyrate promotes T-cell IL-10 production at least partially through Blimp1. Rag1-/- mice transferred with butyrate-treated T cells demonstrated less severe colitis, compared with transfer of untreated T cells, and administration of anti-IL-10R antibody exacerbated colitis development in Rag-/- mice that had received butyrate-treated T cells. Mechanistically, the effects of butyrate on the development of Th1 cells was through inhibition of histone deacetylase but was independent of GPR43. Conclusions These data indicate that butyrate controls the capacity of T cells in the induction of colitis by differentially regulating Th1 and Th17 cell differentiation and promoting IL-10 production, providing insights into butyrate as a potential therapeutic for the treatment of inflammatory bowel disease.

Induction of T-cell development from human cord blood hematopoietic stem cells by Delta-like 1 in vitro

Blood ◽  
2005 ◽  
Vol 105 (4) ◽  
pp. 1431-1439 ◽  
Author(s):  
Ross N. La Motte-Mohs ◽  
Elaine Herer ◽  
Juan Carlos Zúñiga-Pflücker
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
Cord Blood ◽  
T Cell Development ◽  
T Cell Differentiation ◽  
Human Cord Blood ◽  
Hematopoietic Stem

AbstractThe Notch signaling pathway plays a key role at several stages of T-lymphocyte differentiation. However, it remained unclear whether signals induced by the Notch ligand Delta-like 1 could support full T-cell differentiation from a defined source of human hematopoietic stem cells (HSCs) in vitro. Here, we show that human cord blood–derived HSCs cultured on Delta-like 1–expressing OP9 stromal cells undergo efficient T-cell lineage commitment and sustained T-cell differentiation. A normal stage-specific program of T-cell development was observed, including the generation of CD4 and CD8 αβ–T-cell receptor (TCR)–bearing cells. Induction of T-cell differentiation was dependent on the expression of Delta-like 1 by the OP9 cells. Stimulation of the in vitro–differentiated T cells by TCR engagement induced the expression of T-cell activation markers and costimulatory receptors. These results establish an efficient in vitro coculture system for the generation of T cells from human HSCs, providing a new avenue for the study of early T-cell differentiation and function.

scholarly journals CD69 Association with Jak3/Stat5 Proteins Regulates Th17 Cell Differentiation

2010 ◽  
Vol 30 (20) ◽  
pp. 4877-4889 ◽  
Author(s):  
Pilar Martín ◽  
Manuel Gómez ◽  
Amalia Lamana ◽  
Arantxa Cruz-Adalia ◽  
Marta Ramírez-Huesca ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
T Cell ◽  
Th17 Cells ◽  
T Cell Differentiation ◽  
Orphan Receptor ◽  
Interleukin 17 ◽  
Deficient Mice

ABSTRACT T-cell differentiation involves the early decision to commit to a particular pattern of response to an antigen. Here, we show that the leukocyte activation antigen CD69 limits differentiation into proinflammatory helper T cells (Th17 cells). Upon antigen stimulation in vitro, CD4+ T cells from CD69-deficient mice generate an expansion of Th17 cells and the induction of greater mRNA expression of interleukin 17 (IL-17), IL 23 receptor (IL-23R), and the nuclear receptor retinoic acid-related orphan receptor γt (RORγt). In vivo studies with CD69-deficient mice bearing OTII T-cell receptors (TCRs) specific for OVA peptide showed a high proportion of antigen-specific Th17 subpopulation in the draining lymph nodes, as well as in CD69-deficient mice immunized with type II collagen. Biochemical analysis demonstrated that the CD69 cytoplasmic tail associates with the Jak3/Stat5 signaling pathway, which regulates the transcription of RORγt and, consequently, differentiation toward the Th17 lineage. Functional experiments in Th17 cultures demonstrated that the selective inhibition of Jak3 activation enhanced the transcription of RORγt. Moreover, the addition of exogenous IL-2 restored Stat5 phosphorylation and inhibited the enhanced Th17 differentiation in CD69-deficient cells. These results support the early activation receptor CD69 as an intrinsic modulator of the T-cell differentiation program that conditions immune inflammatory processes.

Overlapping functions of human CD3δ and mouse CD3γ in αβ T-cell development revealed in a humanized CD3γ-deficient mouse

Blood ◽  
2006 ◽  
Vol 108 (10) ◽  
pp. 3420-3427 ◽  
Author(s):  
Edgar Fernández-Malavé ◽  
Ninghai Wang ◽  
Manuel Pulgar ◽  
Wolfgang W. A. Schamel ◽  
Balbino Alarcón ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Double Negative ◽  
Wild Type ◽  
Thymocyte Development ◽  
Double Positive ◽  
Deficient Mice ◽  
Αβ T Cells

Abstract Humans lacking the CD3γ subunit of the pre-TCR and TCR complexes exhibit a mild αβ T lymphopenia, but have normal T cells. By contrast, CD3γ-deficient mice are almost devoid of mature αβ T cells due to an early block of intrathymic development at the CD4–CD8– double-negative (DN) stage. This suggests that in humans but not in mice, the highly related CD3δ chain replaces CD3γ during αβ T-cell development. To determine whether human CD3δ (hCD3δ) functions in a similar manner in the mouse in the absence of CD3γ, we introduced an hCD3δ transgene in mice that were deficient for both CD3δ and CD3γ, in which thymocyte development is completely arrested at the DN stage. Expression of hCD3δ efficiently supported pre-TCR–mediated progression from the DN to the CD4+CD8+ double-positive (DP) stage. However, αβTCR-mediated positive and negative thymocyte selection was less efficient than in wild-type mice, which correlated with a marked attenuation of TCR-mediated signaling. Of note, murine CD3γ-deficient TCR complexes that had incorporated hCD3δ displayed abnormalities in structural stability resembling those of T cells from CD3γ-deficient humans. Taken together, these data demonstrate that CD3δ and CD3γ play a different role in humans and mice in pre-TCR and TCR function during αβ T-cell development.

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