IL-1 is a key cytokine involved in the inflammatory response. The type II receptor of IL-1 (IL-1RII) acts as a decoy receptor, binding and inhibiting the effect of IL-1. Colotta et al. (1993) reported results they interpreted as indicating that interleukin-1 acts on myelomonocytic cells through the type I receptor and that the type II receptor inhibits IL1 activity by acting as a decoy target for IL1.
McMahan et al. (1991) used an expression cloning method to isolate human and murine cDNA clones encoding the type II IL1 receptor. The mature receptor was found to consist of a ligand-binding portion comprised of 3 immunoglobulin-like domains, a single transmembrane region, and a short cytoplasmic domain of 29 amino acids. The last contrasts with the 215 amino acid cytoplasmic domain of the type I receptor (IL1RA) and suggests that the 2 receptors may interact with different signal transduction pathways. Both IL1 receptors appear to be well conserved in evolution and map to the same chromosomal region. The molecular mass of the type I receptor is about 80,000; that of the type II receptor is about 60,000. The type II receptor was mapped to 2q12-q22 by study of somatic cell hybrids and in situ hybridization. IL1A and IL1B, the human genes for interleukin-1, map to 2q13-q21. The two IL1R genes map to mouse chromosome 1; in contrast to the human, the mouse Il1 genes map to a separate chromosome, i.e., chromosome 2.
Dale et al. (1999) showed by radiation hybrid mapping that IL1R1, IL1R2, IL1RL2 (Interleukin 1 Receptor-like 2), IL1RL1 (Interleukin 1 Receptor-like 1), and IL18R1 (Interleukin 18 Receptor 1) map to 2q12 and are transcribed in the same direction, with IL1R2 being transcribed towards the cluster.
NCBI Summary:
The protein encoded by this gene is a cytokine receptor that belongs to the interleukin 1 receptor family. This protein binds interleukin alpha (IL1A), interleukin beta (IL1B), and interleukin 1 receptor, type I(IL1R1/IL1RA), and acts as a decoy receptor that inhibits the activity of its ligands. Interleukin 4 (IL4) is reported to antagonize the activity of interleukin 1 by inducing the expression and release of this cytokine. This gene and three other genes form a cytokine receptor gene cluster on chromosome 2q12. Two alternatively spliced transcript variants encoding the same protein have been reported.
General function
Receptor
Comment
The interleukin-1 system mediates inflammation and immunity, and is activated by macrophages, keratinocytes, stimulated B lymphocytes, and fibroblasts.
Cellular localization
Plasma membrane
Comment
Ovarian function
Oogenesis, Oocyte maturation
Comment
The increased intraovarian expression of IL-1R1 in granulosa cells during the periovulatory period implies that it is involved in the ovulatory process Scherzer et al. (1996) Since IL-1R2 is believed to function as a decoy target for IL1, IL-1Rt1 is thought to also be involved in the ovulatory process. But the results of periovulatory expression of IL-1R2 in the ovary are inconclusive. Segments of the cDNAs for rat type I and type II IL-1 receptors were cloned and used as probes in RNase protection assays and in situ hybridization. Tissues obtained from immature rats and hormonally treated rat ovaries were examined. The relative amount of ovarian IL-1R1 transcripts increased after the administration of hCG to pregnant mare serum gonadotropin-primed immature rats. But ovarian expression of IL-1R2 mRNA was observed only before ovulation in amounts that were approximately 70-fold lower than IL-1R1. Scherzer et al. (1996) Similarly, although molecular probing of whole ovarian material in the course of a simulated estrous cycle revealed a progressive preovulatory increase in IL-1beta and type I IL-1R transcripts to an in vivo peak at the time of, comparable efforts to localize and probe for type II IL-IR transcripts failed to elicit a detectable signal. Kol et al. (1999)
Genes whose expression is detected by cDNA array hybridization: cell surface antigens, cell adhesion, receptors Rozenn Dalbis-Tran and Pascal Mermilloda
Expression regulated by
Comment
The type II IL-1R was undetectable in vivo, its in vitro expression pattern proving IL-1- and hCG-independent. Kol et al. (1999)
Ovarian localization
Oocyte, Granulosa, Theca
Comment
In situ hybridization localized type I IL-1R transcripts to the granulosa cell compartment, the innermost layers of the theca interna and to the oocyte of the untreated immature ovary. Kol et al. (1999)