Journal: The Journal of Experimental Medicine
Article Title: IL-24 intrinsically regulates Th17 cell pathogenicity in mice
doi: 10.1084/jem.20212443
Figure Lengend Snippet: Intracellular IL-24 localizes to the inner mitochondrial membrane and is necessary and sufficient for IL-10 production by Th17 cells. (a) Naive T cells from Il24 +/+ wild-type or Il24 −/− mice were cultured in Th17 differentiation conditions for 3 d. Th17 cells were nucleofected with pIRES-eGFP, pIRES-eGFP-IL-24, or pIRES-eGFP-IL-24t on day 1 and analyzed for intracellular IL-10 on day 3 with representative FACS plots (left, pregated for viable CD4 + GFP + cells) and summary of four independent experiments (mean ± SEM) normalized to wild type (right). Relative fraction indicates IL-10 + frequency (among CD4 + cells) for the respective nucleofection, divided by the corresponding IL-10 + frequency of the Il24 +/+ pIRES-eGFP nucleofected (control) cells for each experiment. Asterisks indicate significance level of Dunnett’s multiple comparison test after one-way ANOVA (*, P < 0.05). (b) Naive T cells from wild-type mice were cultured in Th17 differentiation conditions. On day 2 of differentiation, cells were nucleofected with mRuby2-N1-IL-24t (top row) or mRuby2-N1-IFN-γt (bottom row) and analyzed for intracellular cytokine distribution by confocal microscopy. Mitochondria were marked with Mitotracker. Representative microphotographs; scale bar, 2 μm (left). Quantification of the cytokine signal in the mitochondrial compartment (right) from three independent experiments (mean ± SEM). Asterisk indicates statistical significance of a two-tailed t test. (c) Naive wild-type or Il24 −/− T cells mice were differentiated into Th17 cells. On day 3, mitochondrial (Mito.) and nuclear (Nucl.) fractions were isolated and probed for STAT3. Lamin B1 and NDUFA9 were used as loading controls for nuclear and mitochondrial fractions, respectively (left). Densitometric quantification (right) of three independent experiments (mean ± SEM). Asterisk indicates statistical significance of a two-tailed t test. (d) Grim19 interacts with STAT3 in an IL-24–dependent manner. Naive T cells from wild-type or Il24 −/− mice were differentiated into Th17 cells. On day 3, cells were transferred into medium containing IL-2 (2 ng/ml). After 24 h, mitochondrial fractions were isolated, solubilized, immunoprecipitated with anti-Grim19 monoclonal antibody (Grim19 IP ), and probed for the amount of pulled STAT3 by Western blot. Solubilized mitochondrial fraction (input) was used as a control for coimmunoprecipitation. Representative Western blots from three independent experiments. (e) Loss of STAT3 from nuclear compartment. Naive T cells from wild-type or Il24 −/− mice were cultured in Th17 differentiation conditions for 3 d. After 3 d, cells were transferred into IL-2 medium (2 ng/ml) and analyzed for STAT3 in the nuclear compartment at baseline and after 6, 12, and 24 h. Representative Western blots (left) with normalized densitometry data (right) quantified from three to six independent experiments (mean ± SEM). Asterisks indicate significance level of Sidak’s multiple comparison test following two-way ANOVA (*, P < 0.05). Source data are available for this figure: .
Article Snippet: The sequences corresponding to full-length or nonsecretable (truncated) versions of IL-24, i.e., IL-24 and IL-24t, were cloned into mammalian expression vector pIRES-eGFP (6029-1; Clontech).
Techniques: Cell Culture, Confocal Microscopy, Two Tailed Test, Isolation, Immunoprecipitation, Western Blot