scholarly journals Pak2 is required for actin cytoskeleton remodeling, TCR signaling, and normal thymocyte development and maturation

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Hyewon Phee ◽  
Byron B Au-Yeung ◽  
Olga Pryshchep ◽  
Kyle Leonard O'Hagan ◽  
Stephanie Grace Fairbairn ◽  
...  
Keyword(s):  
T Cell ◽  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Critical Function ◽  
Cytoskeletal Remodeling ◽  
Single Positive ◽  
Cytoskeleton Remodeling ◽  
P21 Activated Kinase

The molecular mechanisms that govern thymocyte development and maturation are incompletely understood. The P21-activated kinase 2 (Pak2) is an effector for the Rho family GTPases Rac and Cdc42 that regulate actin cytoskeletal remodeling, but its role in the immune system remains poorly understood. In this study, we show that T-cell specific deletion of Pak2 gene in mice resulted in severe T cell lymphopenia accompanied by marked defects in development, maturation, and egress of thymocytes. Pak2 was required for pre-TCR β-selection and positive selection. Surprisingly, Pak2 deficiency in CD4 single positive thymocytes prevented functional maturation and reduced expression of S1P1 and KLF2. Mechanistically, Pak2 is required for actin cytoskeletal remodeling triggered by TCR. Failure to induce proper actin cytoskeletal remodeling impaired PLCγ1 and Erk1/2 signaling in the absence of Pak2, uncovering the critical function of Pak2 as an essential regulator that governs the actin cytoskeleton-dependent signaling to ensure normal thymocyte development and maturation.

scholarly journals Restricting Zap70 Expression to CD4+CD8+ Thymocytes Reveals a T Cell Receptor–dependent Proofreading Mechanism Controlling the Completion of Positive Selection

2003 ◽  
Vol 197 (3) ◽  
pp. 363-373 ◽  
Author(s):  
Xiaolong Liu ◽  
Anthony Adams ◽  
Kathryn F. Wildt ◽  
Bruce Aronow ◽  
Lionel Feigenbaum ◽  
...  
Keyword(s):  
T Cell ◽  
Positive Selection ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Novel Approach ◽  
Single Positive ◽  
Tcr Signals

Although T cell receptor (TCR) signals are essential for intrathymic T cell–positive selection, it remains controversial whether they only serve to initiate this process, or whether they are required throughout to promote thymocyte differentiation and survival. To address this issue, we have devised a novel approach to interfere with thymocyte TCR signaling in a developmental stage-specific manner in vivo. We have reconstituted mice deficient for Zap70, a tyrosine kinase required for TCR signaling and normally expressed throughout T cell development, with a Zap70 transgene driven by the adenosine deaminase (ADA) gene enhancer, which is active in CD4+CD8+ thymocytes but inactive in CD4+ or CD8+ single-positive (SP) thymocytes. In such mice, termination of Zap70 expression impaired TCR signal transduction and arrested thymocyte development after the initiation, but before the completion, of positive selection. Arrested thymocytes had terminated Rag gene expression and up-regulated TCR and Bcl-2 expression, but failed to differentiate into mature CD4 or CD8 SP thymocytes, to be rescued from death by neglect or to sustain interleukin 7Rα expression. These observations identify a TCR-dependent proofreading mechanism that verifies thymocyte TCR specificity and differentiation choices before the completion of positive selection.

scholarly journals Author response: Pak2 is required for actin cytoskeleton remodeling, TCR signaling, and normal thymocyte development and maturation

2014 ◽  
Author(s):  
Hyewon Phee ◽  
Byron B Au-Yeung ◽  
Olga Pryshchep ◽  
Kyle Leonard O'Hagan ◽  
Stephanie Grace Fairbairn ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Author Response ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Cytoskeleton Remodeling

Altered thymocyte and T cell development in neonatal mice with hyperoxia-induced lung injury

2018 ◽  
Vol 46 (4) ◽  
pp. 441-449
Author(s):  
Sowmya Angusamy ◽  
Tamer Mansour ◽  
Mohammed Abdulmageed ◽  
Rachel Han ◽  
Brian C. Schutte ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lung Injury ◽  
T Cell Development ◽  
Adaptive Immune System ◽  
Cell Development ◽  
Thymocyte Development ◽  
Double Positive ◽  
Neonatal Mice ◽  
Single Positive

Abstract Background: The adaptive immune system of neonates is relatively underdeveloped. The thymus is an essential organ for adaptive T cell development and might be affected during the natural course of oxygen induced lung injury. The effect of prolonged hyperoxia on the thymus, thymocyte and T cell development, and its proliferation has not been studied extensively. Methods: Neonatal mice were exposed to 85% oxygen (hyperoxia) or room air (normoxia) up to 28 days. Flow cytometry using surface markers were used to assay for thymocyte development and proliferation. Results: Mice exposed to prolonged hyperoxia had evidence of lung injury associated alveolar simplification, a significantly lower mean weight, smaller thymic size, lower mean thymocyte count and higher percentage of apoptotic thymocytes. T cells subpopulation in the thymus showed a significant reduction in the count and proliferation of double positive and double negative T cells. There was a significant reduction in the count and proliferation of single positive CD4+ and CD8+ T cells. Conclusions: Prolonged hyperoxia in neonatal mice adversely affected thymic size, thymocyte count and altered the distribution of T cells sub-populations. These results are consistent with the hypothesis that prolonged hyperoxia causes defective development of T cells in the thymus.

scholarly journals Fyn-Binding Protein (Fyb)/Slp-76–Associated Protein (Slap), Ena/Vasodilator-Stimulated Phosphoprotein (Vasp) Proteins and the Arp2/3 Complex Link T Cell Receptor (Tcr) Signaling to the Actin Cytoskeleton

2000 ◽  
Vol 149 (1) ◽  
pp. 181-194 ◽  
Author(s):  
Matthias Krause ◽  
Antonio S. Sechi ◽  
Marlies Konradt ◽  
David Monner ◽  
Frank B. Gertler ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Actin Cytoskeleton ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Signaling ◽  
Tcr Signaling ◽  
Activated T Cells ◽  
Antigen Presenting ◽  
Syndrome Protein

T cell receptor (TCR)-driven activation of helper T cells induces a rapid polarization of their cytoskeleton towards bound antigen presenting cells (APCs). We have identified the Fyn- and SLP-76–associated protein Fyb/SLAP as a new ligand for Ena/ vasodilator-stimulated phosphoprotein (VASP) homology 1 (EVH1) domains. Upon TCR engagement, Fyb/SLAP localizes at the interface between T cells and anti-CD3–coated beads, where Evl, a member of the Ena/VASP family, Wiskott-Aldrich syndrome protein (WASP) and the Arp2/3 complex are also found. In addition, Fyb/SLAP is restricted to lamellipodia of spreading platelets. In activated T cells, Fyb/SLAP associates with Ena/VASP family proteins and is present within biochemical complexes containing WASP, Nck, and SLP-76. Inhibition of binding between Fyb/SLAP and Ena/VASP proteins or WASP and the Arp2/3 complex impairs TCR-dependent actin rearrangement, suggesting that these interactions play a key role in linking T cell signaling to remodeling of the actin cytoskeleton.

scholarly journals β-Catenin stabilization stalls the transition from double-positive to single-positive stage and predisposes thymocytes to malignant transformation

Blood ◽  
2007 ◽  
Vol 109 (12) ◽  
pp. 5463-5472 ◽  
Author(s):  
Zhuyan Guo ◽  
Marei Dose ◽  
Damian Kovalovsky ◽  
Rui Chang ◽  
Jennifer O'Neil ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Lymphoblastic Leukemia ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Double Positive ◽  
Notch Receptors ◽  
Single Positive ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Genetic Events ◽  
Notch Activation

AbstractActivation of β-catenin has been causatively linked to the etiology of colon cancer. Conditional stabilization of this molecule in pro-T cells promotes thymocyte development without the requirement for pre-TCR signaling. We show here that activated β-catenin stalls the developmental transition from the double-positive (DP) to the single-positive (SP) thymocyte stage and predisposes DP thymocytes to transformation. β-Catenin–induced thymic lymphomas have a leukemic arrest at the early DP stage. Lymphomagenesis requires Rag activity, which peaks at this developmental stage, as well as additional secondary genetic events. A consistent secondary event is the transcriptional up-regulation of c-Myc, whose activity is required for transformation because its conditional ablation abrogates lymphomagenesis. In contrast, the expression of Notch receptors as well as targets is reduced in DP thymocytes with stabilized β-catenin and remains low in the lymphomas, indicating that Notch activation is not required or selected for in β-catenin–induced lymphomas. Thus, β-catenin activation may provide a mechanism for the induction of T-cell–acute lymphoblastic leukemia (T-ALL) that does not depend on Notch activation.

Altered Thymocyte Development in Allogeneic in Utero Hematopoietic Cell Transplantation in the Mouse Model

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4668-4668
Author(s):  
Yan Li ◽  
Jesse D Vrecenak ◽  
Miho Watanabe ◽  
Haiying Li ◽  
Jacqueline Tsai ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cell ◽  
Cell Transplantation ◽  
Hematopoietic Cell Transplantation ◽  
Thymocyte Development ◽  
Cell Compartment ◽  
Thymic Development ◽  
Time Points ◽  
Single Positive

Abstract Abstract 4668 Introduction In Utero Hematopoietic Cell Transplantation (IUHCT) is a promising therapeutic strategy for congenital hematopoietic disorders. While mixed allogeneic hematopoietic chimerism with associated donor specific tolerance is routinely achieved by a predominant mechanism of central deletion, the critical events of donor and host thymocyte development have not been analyzed. In this study, we utilized the murine model of allogeneic IUHCT and analyzed donor and host thymocyte development. Methods Bone marrow (BM) cells (10×106) from Foxp3GFP C57/BL6 (B6, H2kb) mice were injected intravenously into Foxp3GFP Balb/c (H2kd) fetuses at embryonic day 14 (E14). At indicated postnatal time points the thymocytes were analyzed by multi-color flow cytometry. Results The results demonstrate that the thymic processing of donor BM-derived thymocytes differs significantly from host thymocytes and from thymocyte development in normal B6 and Balb/c control mice. Though each subpopulation of the host's thymocytes showed comparable levels to the normal untransplanted Balb/c mice, the donor BM-derived thymocytes demonstrated significantly higher proportions of CD4+CD8- and CD4-CD8+ single positive cells, and a dramatically lower proportion of CD4+CD8+ double positive cells compared to their donor-derived counterparts, respectively. These discrepancies increased with each analysis time point up to 12 weeks. Immature single positive cells, including both TCRb-CD4+CD8- and TCRb-CD4-CD8+ cells, were significantly higher in the donor-derived thymocytes than the host, indicating the development of the donor BM-derived thymocytes were impeded at the DN-DP stage in this specific allogeneic IUHCT setting. In addition, we also found higher frequencies and more potent suppressive capacity of regulatory T cells in the donor-derived T cell compartment than in the host T cell compartment. In the reversed allogeneic strain combination, i.e. IUHCT of Foxp3GFP Balb/c BM MNCs into the E14 Foxp3GFP B6 recipients, thymocytes of both origins showed imbalanced intra-thymic development that differed from the normal mouse. Conclusion Our data in the current study suggests that immune reconstitution of the donor bone marrow derived thymocytes differs from that of the host cells and that of normal mice in an allogeneic IUHCT system. The mechanism of the altered thymic development in allogeneic IUHCT, and the potential importance of these observations for clinical IUHCT remains to be determined. Bone marrow (BM) cells (10×106) from Foxp3GFP C57/BL6 (B6, H2kb) mice were injected intravenously into Foxp3GFP Balb/c (H2kd) fetuses at embryonic day 14 (E14). At indicated postnatal time points the thymocytes were analyzed by multicolor flow cytometry (Fig. A), and the expression of TCR¦Â in each individual subpopulation in 4-week old mice was measured (Fig. B). Disclosures: No relevant conflicts of interest to declare.

scholarly journals Pre–T Cell Receptor (Tcr) and Tcr-Controlled Checkpoints in T Cell Differentiation Are Set by Ikaros

1999 ◽  
Vol 190 (8) ◽  
pp. 1039-1048 ◽  
Author(s):  
Susan Winandy ◽  
Li Wu ◽  
Jin-Hong Wang ◽  
Katia Georgopoulos
Keyword(s):  
Cell Differentiation ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Differentiation ◽  
Tcr Signaling ◽  
Double Positive ◽  
Single Positive ◽  
T Cell Malignancies ◽  
Deficient Mice

T cell differentiation relies on pre–T cell receptor (TCR) and TCR signaling events that take place at successive steps of the pathway. Here, we show that two of these T cell differentiation checkpoints are regulated by Ikaros. In the absence of Ikaros, double negative thymocytes can differentiate to the double positive stage without expression of a pre-TCR complex. Subsequent events in T cell development mediated by TCR involving transition from the double positive to the single positive stage are also regulated by Ikaros. Nonetheless, in Ikaros-deficient thymocytes, the requirement of pre-TCR expression for expansion of immature thymocytes as they progress to the double positive stage is still maintained, and the T cell malignancies that invariably arise in the thymus of Ikaros-deficient mice are dependent on either pre-TCR or TCR signaling. We conclude that Ikaros regulates T cell differentiation, selection, and homeostasis by providing signaling thresholds for pre-TCR and TCR.

scholarly journals The transcription factor Gli3 regulates differentiation of fetal CD4–CD8– double-negative thymocytes

Blood ◽  
2005 ◽  
Vol 106 (4) ◽  
pp. 1296-1304 ◽  
Author(s):  
Ariadne L. Hager-Theodorides ◽  
Johannes T. Dessens ◽  
Susan V. Outram ◽  
Tessa Crompton
Keyword(s):  
Transcription Factor ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Differentiation ◽  
Double Negative ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Double Positive ◽  
Dose Dependent

AbstractGlioblastoma 3 (Gli3) is a transcription factor involved in patterning and oncogenesis. Here, we demonstrate a role for Gli3 in thymocyte development. Gli3 is differentially expressed in fetal CD4–CD8– double-negative (DN) thymocytes and is most highly expressed at the CD44+ CD25– DN (DN1) and CD44–CD25– (DN4) stages of development but was not detected in adult thymocytes. Analysis of null mutants showed that Gli3 is involved at the transitions from DN1 to CD44+ CD25+ DN (DN2) cell and from DN to CD4+CD8+ double-positive (DP) cell. Gli3 is required for differentiation from DN to DP thymocyte, after pre–T-cell receptor (TCR) signaling but is not necessary for pre-TCR–induced proliferation or survival. The effect of Gli3 was dose dependent, suggesting its direct involvement in the transcriptional regulation of genes controlling T-cell differentiation during fetal development.

scholarly journals Disregulated expression of the transcription factor ThPOK during T-cell development leads to high incidence of T-cell lymphomas

2015 ◽  
Vol 112 (25) ◽  
pp. 7773-7778 ◽  
Author(s):  
Hyung-Ok Lee ◽  
Xiao He ◽  
Jayati Mookerjee-Basu ◽  
Dai Zhongping ◽  
Xiang Hua ◽  
...  
Keyword(s):  
Transcription Factor ◽  
T Cell ◽  
Lymphoblastic Leukemia ◽  
T Cell Development ◽  
Cell Receptor ◽  
Cell Development ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Double Positive ◽  
Human T Cell

The transcription factor T-helper-inducing POZ/Krueppel-like factor (ThPOK, encoded by the Zbtb7b gene) plays widespread and critical roles in T-cell development, particularly as the master regulator of CD4 commitment. Here we show that mice expressing a constitutive T-cell–specific ThPOK transgene (ThPOKconst mice) develop thymic lymphomas. These tumors resemble human T-cell acute lymphoblastic leukemia (T-ALL), in that they predominantly exhibit activating Notch1 mutations. Lymphomagenesis is prevented if thymocyte development is arrested at the DN3 stage by recombination-activating gene (RAG) deficiency, but restored by introduction of a T-cell receptor (TCR) transgene or by a single injection of anti-αβTCR antibody into ThPOKconst RAG-deficient mice, which promotes development to the CD4+8+ (DP) stage. Hence, TCR signals and/or traversal of the DN (double negative) > DP (double positive) checkpoint are required for ThPOK-mediated lymphomagenesis. These results demonstrate a novel link between ThPOK, TCR signaling, and lymphomagenesis. Finally, we present evidence that ectopic ThPOK expression gives rise to a preleukemic and self-perpetuating DN4 lymphoma precursor population. Our results collectively define a novel role for ThPOK as an oncogene and precisely map the stage in thymopoiesis susceptible to ThPOK-dependent tumor initiation.

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