1. Proteolytic Cleavage Governs Interleukin-11 Trans-signaling
Juliane Lokau, Rebecca Nitz, Maria Agthe, Niloufar Monhasery, Samadhi Aparicio-Siegmund, Neele Schumacher, Janina Wolf, Katja Möller-Hackbarth, Georg H. Waetzig, Joachim Grötzinger, Gerhard Müller-Newen, Stefan Rose-John, Jürgen Scheller, Christoph Garbers 
Cell Reports 
Volume 14, Issue 7, Pages (February 2016)
DOI: /j.celrep
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2. Cell Reports 2016 14, 1761-1773DOI: (10.1016/j.celrep.2016.01.053)
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3. Figure 1 The IL-11R Is No Substrate for ADAM17
(A) HEK293 cells were transiently transfected with a plasmid encoding the human IL-6R and treated with 100 nM PMA for 2 hr. Soluble receptors in the cell-culture supernatant were analyzed by ELISA. The amount of soluble receptor without stimulation was set to 1, and the increase after PMA stimulation was calculated accordingly (n = 3, mean ± SD). ∗p < 0.05.
(B) The experiment was performed as described in (A), but the cells were pre-treated for 30 min with the metalloprotease inhibitors GI and GW where indicated. Soluble IL-6R was precipitated from cell-culture supernatant and visualized by western blot. Cells were lysed, and IL-6R expression was also determined via western blot. GAPDH served as loading control. Western blots from three independent experiments were quantified (mean ± SD). ∗p < 0.05.
(C and D) HEK293 cells were transiently transfected with a plasmid encoding the human IL-11R, and experiments were performed as described for (A) and (B). Error bars indicate mean ± SD. ns, not significant.
(E) HeLa cells were transiently transfected with either IL-6R or IL-11R. Cells were grown on coverslips for 48 hr, stimulated as indicated, and were fixed and stained. Cytokine receptors are stained in red, and the nucleus is stained in blue (DAPI). Scale bars, 10 μm.
(F) THP-1 cells were stimulated with 100 nM PMA with or without pretreatment with the protease inhibitors GI or GW, and cytokine receptor levels at the cell surface were analyzed via flow cytometry.
See also Figure S1.
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4. Figure 2
The Stalk Region of the IL-6R Determines Its Cleavage Specificity
(A) Schematic overview of the IL-6R and chimeric variants thereof. IL-6R and IL-11R share the same overall topology, consisting of an immunoglobulin (Ig)-like domain (D1), two fibronectin type III domains (D2 and D3), a stalk (S) region, a transmembrane (TM) region, and an intracellular domain (ICD). The IL-6R is depicted in orange, whereas regions originating from the IL-11R are shown in blue. The values shown besides the chimeras are the x-fold increase after PMA stimulation (mean ± SD, n = 3). To calculate this, the amount of constitutively shed IL-6R or chimera was measured by ELISA and arbitrarily set to 1. The increase after stimulation with PMA was calculated accordingly. Chimeras with at least a 2-fold increase in soluble receptor formation were defined as good substrates for ADAM17 (colored in green), whereas chimeras with values below this were considered weak substrates (colored in red).
(B–G) HEK293 cells were transiently transfected with plasmids encoding IL-6R-TM (B and C), IL-6R-ICD (D and E), IL-6R-S (F), or IL-6R-10AS (G), and the amount of shedding upon PMA stimulation was analyzed by ELISA and western blot, as described in the legend for Figure 1 (mean ± SD). ∗p < 0.05; ns, not significant.
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5. Figure 3
Susceptibility toward Cleavage by ADAM17 Can Be Transferred from the IL-6R to the IL-11R
(A) Schematic overview of the IL-11R and chimeric variants thereof. IL-6R and IL-11R share the same overall topology, consisting of an immunoglobulin (Ig)-like domain (D1), two fibronectin type III domains (D2 and D3), a stalk (S) region, a transmembrane (TM) region, and an intracellular domain (ICD). The IL-11R is depicted in blue, whereas regions originating from the IL-6R are shown in orange. The values shown beside the chimeras are the x-fold increase after PMA stimulation (mean ± SD, n = 3). To calculate this, the amount of constitutively shed IL-11R or chimera was measured by ELISA and arbitrarily set to 1. The increase after stimulation with PMA was calculated accordingly. Chimeras with at least a 2-fold increase in soluble receptor formation were defined as good substrates for ADAM17 (colored in green), whereas chimeras with values below this were considered weak substrates (colored in red). IL-11R-S/T/I and IL-11R-S could not be detected via ELISA.
(B–E) HEK293 cells were transiently transfected with plasmids encoding IL-11R-S/T/I (B), IL-11R-S (C), or IL-11R-10AS (D and E), and the amount of shedding upon PMA stimulation was analyzed by ELISA and western blot as described in the legend to Figure 1 (mean ± SD; n = 3). ∗p < 0.05.
See also Figure S2.
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6. Figure 4 ADAM10 Cleaves the IL-11R
(A and B) HEK293 cells were transiently transfected with plasmids encoding the human IL-6R (A) or the human IL-11R (B) and stimulated with 1 μM ionomycin (Iono) for 1 hr, with or without pre-incubation with the ADAM inhibitors GI or GW. Soluble receptors were precipitated from cell-culture supernatant and visualized by western blot. Cells were lysed, and the lysates were also analyzed by western blot. GAPDH served as loading control. Western blots from three independent experiments were quantified (mean ± SD). ∗p < 0.05.
(C) MEFs from wild-type (wt) animals and from mice deficient in ADAM10, ADAM17, or both proteases were transiently transfected with IL-11R. Cells were stimulated, and shedding was analyzed by western blots as described for (A) and (B). Western blots from three independent experiments were quantified (mean ± SD). ∗p < 0.05; ns, not significant.
(D) ADAM10-mediated proteolysis of IL-6R and IL-11R in HeLa cells was analyzed as described in the legend to Figure 1. Scale bars, 10 μm.
(E) THP-1 cells were stimulated with 1 μM ionomycin, and the amount of cytokine receptor at the cell surface was analyzed by flow cytometry.
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7. Figure 5
Arginine-355 Is Required for ADAM10-Mediated Shedding of the IL-11R
(A) Schematic overview of the IL-11R and deletion variants thereof. The amino acid sequence from Ser-316 to Ile-374 is shown, with the sequence of the stalk region highlighted in blue. The range of each deletion is shown in front of the schematic drawing.
(B) HEK293 cells were transiently transfected with plasmids encoding the human IL-11R or deletion variants thereof and stimulated with ionomycin (Iono) for 1 hr where indicated. Soluble receptors were precipitated from cell-culture supernatant and visualized by western blot. Cells were lysed, and the lysates were also analyzed by western blot. GAPDH served as loading control. Western blots from three independent experiments were quantified (mean ± SD). ∗p < 0.05; ns, not significant.
(C) HEK293 cells were transiently transfected with IL-11R or the R355E mutant, and ectodomain shedding was analyzed. Experiments were performed as described for (B), but cells were pre-incubated with the protease inhibitors GI or GW where indicated. One representative western blot is shown.
(D) Relative proteolysis of (C) (mean ± SD). ∗p < 0.05.
See also Figure S3.
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8. Figure 6 Trans-signaling via the sIL-11R Is Blocked by sgp130Fc
(A) Ba/F3-gp130 cells were incubated with 10 ng/ml recombinant IL-11 and increasing amounts of recombinant sIL-11R for 48 hr. Significant increased proliferation, compared to no addition of sIL-11R, is indicated. Error bars indicate mean ± SD. ∗p < 0.05; n = 3. RLU, relative light units.
(B) Ba/F3-gp130 cells were incubated with 10 ng/ml recombinant IL-11, 1 μg/ml recombinant sIL-11R, and increasing amounts of sgp130Fc. Significant reduced proliferation, compared to no addition of sgp130Fc, is indicated. Error bars indicate mean ± SD. ∗p < 0.05; n = 3.
(C) HEK293 cells were transfected with IL-11R and stimulated with ionomycin with or without pre-incubation with GI or GW as indicated. The supernatant was collected, and Ba/F3-gp130 cells were incubated with the conditioned-cell supernatant (IL-11R SN) in the presence or absence of IL-11 for 48 hr. Error bars indicate mean ± SD. ∗p < 0.05; n = 3.
(D) Conditioned cell supernatant from IL-11R expressing HEK293 cells stimulated with ionomycin (IL-11R SN Iono) was produced as described for (C), and Ba/F3-gp130 cells were incubated with this medium in the presence of IL-11 and increasing amounts of sgp130Fc for 48 hr. Significant reduced proliferation, compared to no addition of sgp130Fc, is indicated. Error bars indicate mean ± SD. ∗p < 0.05; n = 3.
(E) Ba/F3-gp130 cells were serum starved for 2 hr and then stimulated with conditioned medium from IL-11R-expressing HEK293 cells in the presence or absence of IL-11 and sgp130Fc. Ba/F3-gp130 cells were lysed, and STAT3 phosphorylation was analyzed by western blot. Western blots from three independent experiments were quantified (mean ± SD). ∗p < 0.05; ns, not significant.
See also Figure S4.
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9. Figure 7
Cleavage of IL-6R and IL-11R by Neutrophil-Derived Serine Proteases
(A) HepG2 cells were incubated for 2 hr with the indicated concentrations of purified neutrophil-derived serine proteases (NE, CG, and PR3) under serum-free conditions. Levels of the sIL-6R in cell-culture supernatants were determined by ELISA. Error bars indicate mean ± SD.
(B) IL-11R expression on CD66b+ human primary neutrophils from eight healthy volunteers was analyzed via flow cytometry. The mean is indicated by a horizontal line.
(C) HEK293 cells were transiently transfected with a construct coding for the IL-11R. 48 hr post-transfection, cells were incubated for 2 hr with the indicated concentrations of purified neutrophil-derived serine proteases under serum-free conditions. Soluble IL-11R from cell-culture supernatants was precipitated with TCA and analyzed by western blot. Additionally, cells were lysed, and IL-11R levels in whole-cell lysates were analyzed by western blot. GAPDH served as loading control.
(D and E) HEK293 cells were transfected with IL-11R or IL-6R and incubated with recombinant NE or CG or left untreated. The supernatants were collected, and Ba/F3-gp130 cells were incubated with the conditioned cell supernatant (IL-11R SN or IL-6R SN) in the presence or absence of IL-11 or IL-6 for 48 hr where indicated. One of two performed experiments with similar outcome is shown (mean ± SD). ∗p < 0.05; ns, not significant.
(F–I) Serum samples from 21 healthy volunteers were analyzed for IL-6, IL-11, sIL-6R, and sIL-11R. Means are indicated by a horizontal line.
See also Figures S5 and S6.
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