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Identification of a human cDNA encoding a functional high affinity lipoxin A4 receptor
S Fiore1, J F Maddox, H D Perez
1Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.
The Journal of Experimental Medicine
|July 1, 1994
Summary
Researchers identified a novel receptor candidate, pINF114, for Lipoxin A4 (LXA4) in human myeloid cells. This G-protein coupled receptor binds LXA4 with high affinity and mediates cellular responses, offering new therapeutic targets.
Area of Science:
- Immunology and Molecular Biology
- Receptor pharmacology
- Signal transduction
Background:
- Lipoxin A4 (LXA4) is a lipid mediator involved in inflammatory responses.
- LXA4 elicits specific cellular effects in human neutrophils via high-affinity receptors.
- The precise molecular identity of the LXA4 receptor in myeloid cells remained elusive.
Purpose of the Study:
- To characterize the binding and signaling properties of LXA4 receptors.
- To identify and validate orphan cDNAs encoding potential LXA4 receptors.
- To investigate the functional role of the identified receptor in cellular signaling.
Main Methods:
- Radioligand binding assays using [11,12-(3)]LXA4 on neutrophil membranes.
- Expression of orphan cDNAs in Chinese hamster ovary (CHO) cells.
- Ligand displacement studies, GTPase activity assays, and arachidonate release measurements.
Main Results:
- High-affinity LXA4 binding sites were confirmed on neutrophil granule and plasma membranes.
- CHO cells transfected with pINF114 cDNA exhibited specific, high-affinity [3H]LXA4 binding.
- LXA4 stimulated GTPase activity and arachidonate release in pINF114-transfected cells, which was pertussis toxin-sensitive.
Conclusions:
- The pINF114 cDNA encodes a 7-transmembrane protein that binds LXA4 with high affinity.
- This protein mediates LXA4-induced signaling, including GTPase activation and arachidonate release.
- pINF114 is a strong candidate for the LXA4 receptor in human myeloid cells.