Title
Differential TCR signaling dynamics tune graded gene expression in early-activating CD8+ T cells
ORCID ID
0000-0002-7799-0546
Publication Date
2020-11-13
Document Type
Doctoral Dissertation
Academic Program
Immunology and Microbiology
Department
Pathology
First Thesis Advisor
Leslie J. Berg
Keywords
Immunology, T cell Receptor Signaling, TCR, ITK, T cell Activation
Abstract
The strength of peptide:MHC interactions with the T cell receptor (TCR) is correlated with the time to first cell division, the relative scale of the effector cell response, and the graded expression of activation-induced proteins. The TCR proximal tyrosine kinase ITK simultaneously influences many biochemically separate signaling cascades. T cells lacking ITK exhibit selective impairments in effector T cell responses after activation, but under the strongest signaling conditions ITK activity is dispensable. To gain insight into whether TCR signal strength and ITK activity tune observed graded gene expression through unequal activation of disparate signaling pathways, I examined NFAT, NF-κB and MAP kinase pathways during early activation of individual naïve OT-I CD8+ T cells using peptide-loaded antigen presenting cells. Utilizing both measurement of transcription factor translocation in single T cell nuclei and conventional phospho-flow cytometry, I observed digital activation of Erk-MAPK and NFAT1 at all peptide doses and avidities. However, NF-κB activation showed a graded response to variation in TCR signal strength and was more sensitive to treatment with an ITK inhibitor. Inhibitor-treated cells showed poor induction of AP-1 factors Fos and Fosb, NF-κB response gene transcripts, and survival factor Il2 transcripts. ATAC-seq analysis revealed genomic regions most sensitive to ITK inhibition are enriched for NF-κB and AP-1 motifs. Together, these data indicate a key role for ITK in orchestrating optimal activation of separate TCR downstream pathways, specifically aiding NF-κB activation. More broadly, I describe a mechanism by which variation in TCR signal strength can produce patterns of graded gene expression in activated T cells.
Repository Citation
Gallagher MP. (2020). Differential TCR signaling dynamics tune graded gene expression in early-activating CD8+ T cells. GSBS Dissertations and Theses. https://doi.org/10.13028/1f67-sx29. Retrieved from https://escholarship.umassmed.edu/gsbs_diss/1115
DOI
10.13028/1f67-sx29
Rights and Permissions
Licensed under a Creative Commons license
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This work is licensed under a Creative Commons Attribution 4.0 License.