Rat homolog of mouse interleukin-1 receptor accessory protein: cloning, localization and modulation studies.
A protein which facilitates the binding between interleukin-1 (IL-1) and the type I IL-1 receptor (designated as interleukin-1 receptor accessory protein, IL-1RAcP) has recently been cloned in mouse cells. In the present study, a rat homolog of the mouse IL-1RAcP was isolated from a rat superior cervical ganglion library. The deduced 570 amino acid sequences between rat and mouse IL-1RAcP have > 95% sequence identity to each other with similar predicted signal peptide sequence (20 amino acids), extracellular domain (339 amino acids), a single transmembrane domain (24 amino acids) and a long intracellular domain (187 amino acids). The rat IL-1RAcP has approximately 25% sequence identity to the rat type I IL-1 receptor and a predicted extracellular domain with three immunoglobulin-like loops. RNase protection assays demonstrated that rat IL-1RAcP is expressed in both brain and peripheral tissues with the highest densities present in liver and brain areas such as hypothalamus, cerebral cortex, hippocampus and cerebellum; significantly lower densities were present in lung and in immune tissues such as thymus and spleen. The presence of IL-1RAcP in brain was confirmed by in situ hybridization histochemical studies with a discrete localization present in the dentate gyrus of the hippocampus. The IL-1RAcp was down-regulated in parallel with the type I IL-1 receptor in the liver following endotoxin treatment in rats. These data demonstrating the presence and modulation of a rat homolog of a mouse IL-1RAcP, which is highly expressed in brain and peripheral tissues containing type I rat IL-1 receptor, further suggest the importance of the interaction between the two proteins in rat in modulating the actions of IL-1. On the other hand, the presence of the IL-1RAcP in brain areas which show an absence of type I IL-1 receptors suggests additional functions for this protein in the rat.
Liu
C
C
Neurocrine Biosciences, Inc., San Diego, CA 92121, USA.
Chalmers
D
D
Maki
R
R
De Souza
E B
EB
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004731:Endotoxins / Q000494:pharmacology; D006651:Histocytochemistry; D017403:In Situ Hybridization; D053577:Interleukin-1 Receptor Accessory Protein; D051379:Mice / Q000378:metabolism*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats / Q000378:metabolism*; D017472:Receptors, Interleukin-1 / Q000235:genetics; D012260:Ribonucleases; D014018:Tissue Distribution
D018076:DNA, Complementary; D004731:Endotoxins; C507767:Il1rap protein, mouse; C507766:Il1rap protein, rat; D053577:Interleukin-1 Receptor Accessory Protein; D015345:Oligonucleotide Probes; D011506:Proteins; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; D012260:Ribonucleases