Molecular cloning of cDNAs encoding a LD78 receptor and putative leukocyte chemotactic peptide receptors

Abstract

Several cDNA clones encoding receptors for leukocyte chemoattractants, including IL-8, C5a, N-formyl peptides (FP), and platelet-activating factor, have been isolated in the past 3 years. The primary structure of these receptors revealed that they are members of the superfamily of G protein-coupled receptors containing seven transmembrane domains. In this study the polymerase chain reaction was carried out to isolate novel cDNA clones encoding human receptors of IL-8 related cytokines, chemokines, from a human monocyte cDNA library using degenerate oligonucleotide primers devised from conserved sequences among the cDNAs encoding the human receptors for IL-8, FP and C5a. Four novel cDNA clones (HM63, HM74, HM89, and HM145) in addition to cDNAs for FP and C5a receptors were isolated. All polypeptides encoded by the cloned cDNAs share common features with the G protein-coupled receptor superfamily, such as seven putative hydrophobic transmembrane domains and, except for HM74, N-linked glycosylation sites near the N-terminus. The amino acid sequence identities among HM63, HM89, HM145, IL-8 receptors, FP receptor, and C5a receptor are in the range of 24-68%, higher than those of other members of the G protein-coupled receptor superfamily. Moreover, the number of amino acids between the fifth and sixth transmembrane domains, which varies within this superfamily, is the same in these receptors. Thus, three of the newly identified proteins probably belong to a 'leukocyte chemotactic peptide receptor family'. HM74 differs from the other clones with respect to the amino acid homology, suggesting that this may be the receptor for a different type of ligand. Furthermore, it was confirmed that HM145 is a functional receptor for LD78, one of the C-C chemokines, as revealed by the measurement of decrease of cAMP accumulation as well as calcium influx using stable transfectants.

Interactions Between Lipoxin A4, the Stable Analogue 16‐phenoxy‐lipoxin A4 and Leukotriene B4 in Cytokine Generation by Human Monocytes

“…the ALX receptor [22,27,39]. ALX was cloned from a human monocyte cDNA library [40]. In ALX-transfected CHO cells, which were tested for binding of LXB4, LTD4, LTB4 and PGE2, only LTD 4 showed competition with LXA 4 binding [22].…”

IL-10 stimulatory effects on human NK cells explored by gene profile analysis

“…By contrast, microarray results showed that IL-10 increased mRNA levels of adhesion/migration-related genes such as L-selectin, VEGF receptor-1, t-PA, HM74, formyl peptide receptor-1 and lipoxin A4 receptor (Figure 3). The last three genes are involved in the synthesis of peptide receptors [38][39][40] that mediates leukocyte chemotaxis by binding peptides derived from protein degrada- tion occurring in damaged/diseased areas. 41 The overexpression of these receptors might play an important role in NK cell migration in response to the liberation of danger signals (eg peptides) freed in the tumor microenvironment.…”

Modulation of CXCR4 expression and SDF-1α functional activity during differentiation of human monocytes and macrophages

“…On the other hand, the ability of SDF-1 to interact with neutrophils and the expression of CXCR4 on their cell surface is controversial. Although two studies demonstrated that neutrophils expressed significant amounts of CXCR4 mRNA [12,13], more recent evidence from a functional study [11], and results using flow cytometry [14], have indicated lack of CXCR4 on neutrophils. Third, SDF-1 is constitutively expressed [15,16], whereas other chemokines are released on stimulation with pro-inflammatory cytokines.…”