title: Deletion of the ST2 proximal promoter disrupts fibroblast-specific expression but does not reduce the amount of soluble ST2 in circulation.
abstract: IL-33 signals through ST2, which is expressed either as a full-length signaling receptor or a truncated soluble receptor that can suppress IL-33 activity. Previous data suggest that soluble ST2 mRNA in fibroblasts is coupled to a serum-inducible proximal promoter, while full-length ST2 expression in immune cells is directed from a distal promoter. In order to better understand the function of the alternative promoters and how they ultimately affect the regulation of IL-33, we generated a mouse in which the ST2 proximal promoter is deleted. Promoter deletion had no impact on ST2 expression in mast cells or their ability to respond to IL-33. In contrast, it resulted in a complete loss of both soluble and full-length ST2 mRNA in fibroblasts, which corresponded with both an inability to secrete soluble ST2 and a defect in IL-33 responsiveness. Importantly, in spite of the fibroblast defect, soluble ST2 concentrations were not reduced in the serum of naïve or allergen-exposed knockout mice. In summary, we found that ST2 promoter usage is largely cell-type dependent but does not dictate splicing. Moreover, the proximal promoter is not a major driver of circulating soluble ST2 under the conditions tested.
authors.affiliation: Department of Inflammation Research, Amgen, Seattle, Washington 98119, USA.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Lipsky
authors.forename: Dean Y
authors.initials: DY
authors.lastname: Toy
authors.forename: David A
authors.initials: DA
authors.lastname: Swart
authors.forename: Molly D
authors.initials: MD
authors.lastname: Smithgall
authors.forename: Dirke
authors.initials: D
authors.lastname: Smith
mesh_terms: D000818:Animals; D005347:Fibroblasts; D005786:Gene Expression Regulation; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D007378:Interleukins / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic; D012313:RNA / Q000737:chemistry / Q000235:genetics; D018123:Receptors, Interleukin / Q000097:blood / Q000235:genetics* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000276:immunology
chemical_list: C486189:Il1rl1 protein, mouse; C506535:Il33 protein, mouse; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D007378:Interleukins; D018123:Receptors, Interleukin; D012313:RNA