The guanine-nucleotide exchange factor CalDAG GEFI fine-tunes functional properties of regulatory T cells

The guanine-nucleotide exchange factor CalDAG GEFI fine-tunes functional properties of regulatory T cells

Using quantitative phosphopeptide sequencing of unstimulated versus stimulated primary murine Foxp3(+) regulatory and Foxp3(-) conventional T cells (Tregs and Tconv, respectively), we detected a novel and differentially regulated tyrosine phosphorylation site within the C1 domain of the guanine-nucl...

Full description

Bibliographic Details
Main Authors: Niemz, Jana, Kliche, Stefanie, Pils, Marina C., Morrison, Eliot, Manns, Annika, Freund, Christian, Galla, Melanie, Jänsch, Lothar, Huehn, Jochen, Crittenden, Jill R, Graybiel, Ann M
Other Authors: Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences
Format: Article
Published: Akademiai Kiado RT 2017
Online Access:http://hdl.handle.net/1721.1/112185
https://orcid.org/0000-0002-4326-7720
Description
Summary:Using quantitative phosphopeptide sequencing of unstimulated versus stimulated primary murine Foxp3(+) regulatory and Foxp3(-) conventional T cells (Tregs and Tconv, respectively), we detected a novel and differentially regulated tyrosine phosphorylation site within the C1 domain of the guanine-nucleotide exchange factor CalDAG GEFI. We hypothesized that the Treg-specific and activation-dependent reduced phosphorylation at Y523 allows binding of CalDAG GEFI to diacylglycerol, thereby impacting the formation of a Treg-specific immunological synapse. However, diacylglycerol binding assays of phosphomutant C1 domains of CalDAG GEFI could not confirm this hypothesis. Moreover, CalDAG GEFI(-/-) mice displayed normal Treg numbers in thymus and secondary lymphoid organs, and CalDAG GEFI(-/-) Tregs showed unaltered in vitro suppressive capacity when compared to CalDAG GEFI(+/+) Tregs. Interestingly, when tested in vivo, CalDAG GEFI(-/-) Tregs displayed a slightly reduced suppressive ability in the transfer colitis model when compared to CalDAG GEFI(+/+) Tregs. Additionally, CRISPR-Cas9-generated CalDAG GEFI(-/-) Jurkat T cell clones showed reduced adhesion to ICAM-1 and fibronectin when compared to CalDAG GEFI-competent Jurkat T cells. Therefore, we speculate that deficiency in CalDAG GEFI impairs adherence of Tregs to antigen-presenting cells, thereby impeding formation of a fully functional immunological synapse, which finally results in a reduced suppressive potential.

Similar Items