IL-33

The homeodomain-like HTH domain mediates nuclear localization and heterochromatin association.

Cytokine that binds to and signals through the IL1RL1/ST2 receptor which in turn activates NF-kappa-B and MAPK signaling pathways in target cells (PubMed:16286016, PubMed:19841166). Involved in the maturation of Th2 cells inducing the secretion of T-helper type 2-associated cytokines (PubMed:17853410, PubMed:18836528). Also involved in activation of mast cells, basophils, eosinophils and natural killer cells (PubMed:17853410, PubMed:18836528). Acts as an enhancer of polarization of alternatively activated macrophages (PubMed:19841166). Acts as a chemoattractant for Th2 cells, and may function as an 'alarmin', that amplifies immune responses during tissue injury (PubMed:17853410, PubMed:18836528). Induces rapid UCP2-dependent mitochondrial rewiring that attenuates the generation of reactive oxygen species and preserves the integrity of Krebs cycle required for persistent production of itaconate and subsequent GATA3-dependent differentiation of inflammation-resolving alternatively activated macrophages (By similarity).

In quiescent endothelia the uncleaved form is constitutively and abundantly expressed, and acts as a chromatin-associated nuclear factor with transcriptional repressor properties, it may sequester nuclear NF-kappaB/RELA, lowering expression of its targets (PubMed:21734074). This form is rapidely lost upon angiogenic or pro-inflammatory activation (PubMed:18787100).

The full-length protein can be released from cells and is able to signal via the IL1RL1/ST2 receptor. However, proteolytic processing by CELA1, CSTG/cathepsin G and ELANE/neutrophil elastase produces C-terminal peptides that are more active than the unprocessed full length protein (PubMed:22307629, PubMed:35794369). May also be proteolytically processed by calpains (PubMed:19596270, PubMed:22307629). Proteolytic cleavage mediated by apoptotic caspases including CASP3 and CASP7 results in IL33 inactivation (PubMed:19559631). In vitro proteolytic cleavage by CASP1 was reported (PubMed:16286016, PubMed:19439663) but could not be confirmed in vivo (PubMed:19465481) suggesting that IL33 is probably not a direct substrate for that caspase (PubMed:19439663, PubMed:19465481).

Belongs to the IL-1 family. Highly divergent.

Expressed at high level in high endothelial venules found in tonsils, Peyer patches and mesenteric lymph nodes. Almost undetectable in placenta.

• Nucleus
• Chromosome
• Cytoplasm
• Cytoplasmic vesicle
• Secretory vesicle
• Secreted
• Secreted and released in the extracellular milieu by passing through the gasdermin-D (GSDMD) pore following cleavage by CELA1 (PubMed:35794369). Associates with heterochromatin and mitotic chromosomes (PubMed:17185418). The secretion is dependent on protein unfolding and facilitated by the cargo receptor TMED10; it results in protein translocation from the cytoplasm into the ERGIC (endoplasmic reticulum-Golgi intermediate compartment) followed by vesicle entry and secretion (PubMed:32272059).

C9orf26, IL1F11, NFHEV, IL33, Interleukin-33, IL-33, Interleukin-1 family member 11, Nuclear factor from high endothelial venules, IL-1F11, NF-HEV

• entrezGene:90865
• omim:608678
• swissprot:O95760

Proteins

Immunology & Infectious Disease

• Cardiovascular
• Immuno-oncology

30759Da