Reciprocal regulation of Th2 and Th17 cells by PAD2-mediated citrullination
Bo Sun, … , Paul R. Thompson, I-Cheng Ho
Bo Sun, … , Paul R. Thompson, I-Cheng Ho
Published November 14, 2019
Citation Information: JCI Insight. 2019;4(22):e129687. https://doi.org/10.1172/jci.insight.129687.
View: Text | PDF
Research Article Immunology

Reciprocal regulation of Th2 and Th17 cells by PAD2-mediated citrullination

Abstract

Dysregulated citrullination, a unique form of posttranslational modification catalyzed by the peptidylarginine deiminases (PADs), has been observed in several human diseases, including rheumatoid arthritis. However, the physiological roles of PADs in the immune system are still poorly understood. Here, we report that global inhibition of citrullination enhances the differentiation of type 2 helper T (Th2) cells but attenuates the differentiation of Th17 cells, thereby increasing the susceptibility to allergic airway inflammation. This effect on Th cells is due to inhibition of PAD2 but not PAD4. Mechanistically, PAD2 directly citrullinates GATA3 and RORγt, 2 key transcription factors determining the fate of differentiating Th cells. Citrullination of R330 of GATA3 weakens its DNA binding ability, whereas citrullination of 4 arginine residues of RORγt strengthens its DNA binding. Finally, PAD2-deficient mice also display altered Th2/Th17 immune response and heightened sensitivity to allergic airway inflammation. Thus, our data highlight the potential and caveat of PAD2 as a therapeutic target of Th cell–mediated diseases.

Authors

Bo Sun, Hui-Hsin Chang, Ari Salinger, Beverly Tomita, Mandar Bawadekar, Caitlyn L. Holmes, Miriam A. Shelef, Eranthie Weerapana, Paul R. Thompson, I-Cheng Ho

×

Figure 6

Identification of functionally critical citrullination sites of GATA3 and RORγt.

Options: View larger image (or click on image) Download as PowerPoint
Identification of functionally critical citrullination sites of GATA3 an...
(A and B) Schematic diagrams of the zinc finger domains of GATA3 (A) and RORγt (B) are shown. The citrullination sites are marked. TA and Zn represent transactivation domain and zinc ion, respectively. (C–H) WT and indicated R-to-K mutants of recombinant GATA3 and RORγt were subjected to in vitro citrullination with PAD2 and stained with Coomassie blue as loading controls (bottom panels of C and F). Their citrullination status was examined with Western blotting using F95 (top panels of C and F, n = 3). The normalized density of the full-length citrullinated proteins (arrows) is shown in the dot plot of C and F. The native and citrullinated proteins were then incubated with indicated DNA probes in EMSA (D and G, n = 3). The normalized density of the shifted probes is shown in the dot plot of D and G. The transcription activity of the WT and various R-to-K mutants was examined with luciferase assays in the presence or absence of PAD2 according to the methods described in Figure 3, C and D. The PAD2-induced fold changes in the activity of GATA3 (E, n = 4) or RORγt (H, n = 4) are shown. One-way ANOVA with correction for multiple comparison was used in C, D, F, and G. Two-tailed Student’s t test was used to compared WT GATA3 with R330K in E, WT GATA3 with 5R-K in E, and WT RORγt with 4R-K in H.