| First Author | Hsu CL | Year | 2012 |
| Journal | J Immunol | Volume | 189 |
| Issue | 7 | Pages | 3421-9 |
| PubMed ID | 22922818 | Mgi Jnum | J:190361 |
| Mgi Id | MGI:5448635 | Doi | 10.4049/jimmunol.1201224 |
| Citation | Hsu CL, et al. (2012) Inducible IL-33 expression by mast cells is regulated by a calcium-dependent pathway. J Immunol 189(7):3421-9 |
| abstractText | IL-33 is an IL-1 family cytokine that displays dual functions: a cytokine via its receptor, T1/ST2, or a chromatin-binding factor within the nucleus. Functionally, it promotes Th2-associated immunity by enhancing the activation and survival of several cell types. However, the pathways regulating IL-33 expression are still unclear. Although several cells display constitutive expression of IL-33, we showed previously that mast cells expressed low levels of IL-33 constitutively but that IL-33 was induced upon IgE-mediated activation. This was mediated via a calcium-dependent mechanism. In this study, we define the pathway through which this inducible IL-33 is regulated. Importantly, this pathway does not alter expression in cells with high constitutive IL-33 expression, such as epithelial cells or fibroblasts. Our data show that, upstream of calcium, inhibition of PI3K and Sphk activity decreases inducible IL-33 expression to IgE/Ag activation. Additionally, expression of Sphk1 short hairpin RNA prevents upregulation of IL-33 expression. Downstream of calcium, NFAT activity is necessary and sufficient for inducible IL-33 expression. We also demonstrate calcium-dependent transcription from two regions of the IL-33 gene that contain putative NFAT-binding sites, one upstream of exon 1 and one upstream of the start site. Interestingly, we show that blocking other calcium pathways, including inositol triphosphate receptor, or NF-kappaB inhibits IgE-driven IL-1beta, another IL-1 family cytokine, but it has no influence on inducible IL-33 expression. In summary, our data demonstrate cell-specific differences in the regulation of IL-33 expression and define a pathway critical for the expression of inducible IL-33 by mast cells upon their activation. |
