Fig. 4. Role of PTPN22 in the regulation of IFNAR signaling by TRAF3 in T cells.

(A to C) WT and TRAF3-deficient HuT28 human T cells were pretreated with a PTPN22 inhibitor (PTPN22i, 10 μM LTV-1), a PTPN2 inhibitor (PTPN2i, 1 nM SF-1670), or an equivalent concentration of DMSO and then were stimulated with type I IFN (1000 U/ml) for the indicated times in the presence of inhibitor or DMSO. (A) Representative Western blotting analysis of pSTAT1 Tyr⁷⁰¹ (left) and quantification of the relative amounts of pSTAT1 from four biological replicates (right). (B) Representative Western blotting analysis of pJAK1 Tyr^1034/1035 (left) and quantification of the relative amounts of pJAK1 from five biological replicates (right). (C) Representative Western blotting analysis of pSTAT1 Tyr⁷⁰¹ (left) and quantification of the relative amounts of pSTAT1 from four biological replicates (right). (D) Representative Western blotting analysis of pSTAT1 Tyr⁷⁰¹ in mouse CD4⁺ T cells (left) that were treated as described in (A) with PTPN22i and type I IFN (left) and quantification of the relative amounts of pSTAT1 from four biological replicates (right), with n = 4 mice per group. Graphs include replicates from four (C and D) and five (B) independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 by two-way ANOVA with Sidak’s multiple comparisons test. Error bars represent the SEM.