Zap70 Is Essential for Long-Term Survival of Naive CD8 T Cells

Abstract

Survival of naive T cells requires engagement of T cell receptor (TCR) with self-peptide major histocompatibility antigens. The signalling pathways required to transmit this survival signal are poorly understood. Here, we ask whether the tyrosine kinase Zap70 is required to transmit survival signals in naive CD8 T cells. In the absence of Zap70 expression, thymic development is completely blocked. Using a tetracycline inducible Zap70 transgene (TetZap70), thymic development of Zap70-deficient TCR transgenic F5 mice was restored. Feeding mice doxycycline (dox) to induce Zap70 expression resulted in repopulation of the peripheral naive compartment. Zap70 transgene expression was then ablated by withdrawal of dox. Survival of Zap70-deficient naive CD8 T cells depended on host environment. In hosts with a replete T cell compartment, naive T cells died rapidly in the absence of Zap70 expression. In lymphopenic hosts, Zap70-deficient T cells survived far longer, in an IL-7 dependent manner, but failed to undergo lymphopenia-induced proliferation. Analysing mixed bone marrow chimeras revealed that intact Zap70 dependent signalling was important for integration of recent thymic emigrants into the mature naive compartment. Finally, we asked whether adaptor function conferred by Zap70 tyrosines 315 and 319 was necessary for transmission of homeostatic TCR signals. This was done by analysing F5 mice expressing mutant Zap70 in which these residues had been mutated to alanines (Zap70YYAA). Inducible Zap70 expression rescued thymic development in F5 TetZap70 Zap70YYAA mice. However, in the absence of WT Zap70 expression, Zap70YYAA mutant failed to transmit either survival or proliferative homeostatic signals.

DNA-binding of the Tet-transactivator curtails antigen-induced lymphocyte activation in mice

“…Additionally, although tTA expression did not perturb thymic T cell development (Supplementary Fig. 3e, f ), in line with observations by others 49 – 52 , the frequency of splenic CD4 + effector/effector memory cells was mildly reduced (Supplementary Fig. 3h ).…”

“…Along the same line, in tTA transactivator mice, we observed significant reduction in effector and effector memory T cells upon immunization and substantial impairment of the virus-specific cytotoxic T-cell response to LCMV infection. Interestingly, neither we, nor others, observed Tet-transactivator-mediated toxic effects during leukocyte development or in unchallenged mice at steady state 44 , 46 , 49 – 52 , 63 , with the exception of a modest reduction in the number of CD8 + cDCs. However, others have already reported that antigen presentation is not impaired in rtTA-expressing DCs upon Dox treatment 64 , therefore we anticipate that antigen presentation to T cells functions in vav-tTA mice as well.…”

Novel Roles for Notch3 and Notch4 Receptors in Gene Expression and Susceptibility to Ozone-Induced Lung Inflammation in Mice

“…In Notch4 –/– mice after ozone exposure, Zap70 was up-regulated (see Supplemental Material, Table S4). Zap70 is part of the T-cell receptor and is crucial for TCR signaling and development of CD8 + cells ( Schim van der Loeff et al 2014 ). In Notch3 –/– mice, the ANOVA analysis indicated that Il33 was up-regulated after 24 hr exposure to ozone, an inducer of Th2 cytokines (see Supplemental Material, Table S2).…”

DNA methylation profiling reveals a pathological signature that contributes to transcriptional defects of CD34+CD15− cells in early chronic‐phase chronic myeloid leukemia

“…Nonetheless, we identified 70 genes that could be aberrantly repressed by DNA methylation in CP‐CML CD34 − CD15 + cells and confirmed the repression of two of them in an independent cohort. Among these genes, ZAP70 encodes a kinase essential for thymopoiesis, T‐cell receptor‐dependent survival, and proliferation (Schim van der Loeff et al ., ) and is aberrantly expressed in B‐cell malignancies, such as acute lymphoblastic leukemia and chronic lymphocytic leukemia (Rassenti et al ., ). This repression could be related to the preferential commitment to the myeloid lineage in CML.…”