UMass Chan Medical School Faculty Publications


Hierarchy of signaling thresholds downstream of the T cell receptor and the Tec kinase ITK

UMMS Affiliation

Department of Pathology; Program in Bioinformatics and Integrative Biology; Garber Lab

Publication Date


Document Type



Amino Acids, Peptides, and Proteins | Enzymes and Coenzymes | Immunopathology


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-associated proteins like IRF4. To regulate T cell activation programming, the TCR and the TCR proximal interleukin-2-inducible T cell kinase (ITK) simultaneously trigger 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 the unequal activation of distinct signaling pathways, we examined Erk1/2 phosphorylation or nuclear factor of activated T cells (NFAT) and nuclear factor (NF)-kappaB translocation in naive OT-I CD8(+) cell nuclei. We observed the consistent digital activation of NFAT1 and Erk1/2, but NF-kappaB displayed dynamic, graded activation in response to variation in TCR signal strength, tunable by treatment with an ITK inhibitor. Inhibitor-treated cells showed the dampened induction of AP-1 factors Fos and Fosb, NF-kappaB response gene transcripts, and survival factor Il2 transcripts. ATAC sequencing analysis also revealed that genomic regions most sensitive to ITK inhibition were enriched for NF-kappaB and AP-1 motifs. Specific inhibition of NF-kappaB during peptide stimulation tuned the expression of early gene products like c-Fos. Together, these data indicate a key role for ITK in orchestrating the optimal activation of separate TCR downstream pathways, specifically aiding NF-kappaB activation. More broadly, we revealed a mechanism by which variations in TCR signal strength can produce patterns of graded gene expression in activated T cells.


ITK, NF-κB, NFAT, T cell activation, T cell receptor signaling

DOI of Published Version



Gallagher MP, Conley JM, Vangala P, Garber M, Reboldi A, Berg LJ. Hierarchy of signaling thresholds downstream of the T cell receptor and the Tec kinase ITK. Proc Natl Acad Sci U S A. 2021 Aug 31;118(35):e2025825118. doi: 10.1073/pnas.2025825118. PMID: 34452995; PMCID: PMC8536361. Link to article on publisher's site

Related Resources

Link to Article in PubMed

Journal/Book/Conference Title

Proceedings of the National Academy of Sciences of the United States of America

PubMed ID