HepG2 cells predominantly express the type II interleukin 1 receptor (biochemical and molecular characterization of the IL-1 receptor).
In this study we have characterized the cell surface interleukin 1 (IL-1) receptor in HepG2 hepatoma cells. We found that HepG2 cells bind both IL-1 alpha and beta with high affinity, KDs of 136 and 180 pM and receptor densities of 16,000 and 8500 binding sites/cell respectively. The binding sites appeared to be predominantly type II since phorbol ester treatment of the cells, which selectively downregulates type II IL-1 receptors, reduced binding by 68% while treatment of the cells with an inhibitory monoclonal antibody specific for the type I receptor had no significant effect on IL-1 binding. Competition studies with a modified IL-1 beta analog (Glu4) also revealed binding kinetics more consistent with binding to type II receptors than to type I. Crosslinking and ligand blotting with human 125I-IL-1 demonstrated the presence of two bands, a 78 kDa band typical of crosslinking to type II (p60) receptor, and a 98 kDa band, typical of crosslinking to the type I (p80) receptor. Low level expression of the type I receptor was consistent with molecular biological studies employing polymerase chain reaction (PCR) amplification which indicated that mRNA for the type I receptor was produced by the HepG2 cells. Functional receptors were demonstrated by the induction of IL-8 by IL-1 stimulated cells.
Giri
J G
JG
Du Pont Merck Pharmaceutical Co., Glenolden, PA 19036.
Robb
R
R
Wong
W L
WL
Horuk
R
R
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001667:Binding, Competitive; D002051:Burkitt Lymphoma / Q000473:pathology; D016466:CHO Cells / Q000187:drug effects / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D006224:Cricetinae; D003432:Cross-Linking Reagents / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D016209:Interleukin-8 / Q000032:analysis; D008113:Liver Neoplasms / Q000473:pathology*; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D010703:Phorbol Esters / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000145:classification / Q000276:immunology; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins / Q000096:biosynthesis; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D007375:Interleukin-1; D016209:Interleukin-8; D009363:Neoplasm Proteins; D010703:Phorbol Esters; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins