Hitherto, the expression of ThPOK in T cell development was believed to be restricted to the ab T cell lineage, in particular to transitional CD4+8lo thymocytes and SP CD4 cells in the thymus and periphery. We now show that a subset of gdTCR+ thymocytes also expresses ThPOK, and that ThPOK expression correlates largely with expression of the activation marker CD44. Furthermore, ThPOK is expressed in KN6 gdTCR transgenic mice in the presence of high but not low affinity ligands. These observations suggest that ThPOK is induced in gd thymocytes in response to strong TCR signals. Significantly, HD-/- mice, which lack functional ThPOK, show a severe defect in development of mature gd thymocytes, while mice expressing ThPOK constitutively show a striking increase, establishing an important role for ThPOK in maturation and/or lineage commitment of gd cells. Given that the importance of TCR signaling and selection for gd development remains highly controversial, establishing a critical role for ThPOK in these processes would represent a significant advance. Hence in Aims 1 and 2 of the current proposal, we propose to address whether ThPOK induction in gd thymocytes is directly regulated by TCR signaling, and whether ThPOK controls positive/negative selection of gd thymocytes and/or commitment to the gd lineage. Interestingly, while ThPOK appears to be required for normal gd development, its expression in preTCR-expressing DN thymocytes leads to a high incidence of thymic lymphomas.
In Aim 3 we propose to identify the cell type and stage in ontogeny at which lymphomagenesis is initiated, and test whether gdTCR expression or gd commitment are sufficient to protect DN thymocytes against ThPOK-mediated lymphomagenesis.

Public Health Relevance

The current proposal deals with the process by which T cells develop to the distinct gd lineage, which we show is controlled by a key transcription factor called ThPOK. How ThPOK controls this process is unknown and the subject of this proposal. Unregulated expression of ThPOK causes blood cell cancer, so that understanding its function is of direct relevance to health.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01CA153260-15
Application #
8607161
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Mccarthy, Susan A
Project Start
Project End
Budget Start
Budget End
Support Year
15
Fiscal Year
2014
Total Cost
Indirect Cost
City
Philadelphia
State
PA
Country
United States
Zip Code
19111
Lee, Hyung-Ok; He, Xiao; Mookerjee-Basu, Jayati et al. (2015) Disregulated expression of the transcription factor ThPOK during T-cell development leads to high incidence of T-cell lymphomas. Proc Natl Acad Sci U S A 112:7773-8
Zhang, Yong; Duc, Anne-Cécile E; Rao, Shuyun et al. (2013) Control of hematopoietic stem cell emergence by antagonistic functions of ribosomal protein paralogs. Dev Cell 24:411-25
Jones-Mason, Mary Elizabeth; Zhao, Xudong; Kappes, Dietmar et al. (2012) E protein transcription factors are required for the development of CD4(+) lineage T cells. Immunity 36:348-61
Engel, Isaac; Zhao, Meng; Kappes, Dietmar et al. (2012) The transcription factor Th-POK negatively regulates Th17 differentiation in Výý14i NKT cells. Blood 120:4524-32
Qiao, Yu; Zhu, Lingqiao; Sofi, Hanief et al. (2012) Development of promyelocytic leukemia zinc finger-expressing innate CD4 T cells requires stronger T-cell receptor signals than conventional CD4 T cells. Proc Natl Acad Sci U S A 109:16264-9
Aliahmad, Parinaz; Kadavallore, Asha; de la Torre, Brian et al. (2011) TOX is required for development of the CD4 T cell lineage gene program. J Immunol 187:5931-40
Kappes, Dietmar J (2011) Developing intestinal fortitude. Nat Immunol 12:281-2
Kim, Sun Taek; Touma, Maki; Takeuchi, Koh et al. (2010) Distinctive CD3 heterodimeric ectodomain topologies maximize antigen-triggered activation of alpha beta T cell receptors. J Immunol 185:2951-9
Kappes, Dietmar J (2010) Expanding roles for ThPOK in thymic development. Immunol Rev 238:182-94
Engel, Isaac; Hammond, Kirsten; Sullivan, Barbara A et al. (2010) Co-receptor choice by V alpha14i NKT cells is driven by Th-POK expression rather than avoidance of CD8-mediated negative selection. J Exp Med 207:1015-29

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