Molecular cloning and characterization of a novel human G-protein-coupled receptor, EDG7, for lysophosphatidic acid.
Lysophosphatidic acid (LPA), together with sphingosine 1-phosphate, is a bioactive lipid mediator that acts on G-protein-coupled receptors to evoke multiple cellular responses, including Ca(2+) mobilization, modulation of adenylyl cyclase, and mitogen-activated protein (MAP) kinase activation. In this study, we isolated a human cDNA encoding a novel G-protein-coupled receptor, designated EDG7, and characterized it as a cellular receptor for LPA. The amino acid sequence of the EDG7 protein is 53.7 and 48.8% identical to those of the human functional LPA receptors EDG2 and EDG4, respectively, previously identified. LPA (oleoyl) but not other lysophospholipids induced an increase in the [Ca(2+)](i) of EDG7-overexpressing Sf9 cells. Other LPA receptors, EDG4 but not EDG2, transduced the Ca(2+) response by LPA when expressed in Sf9 cells. LPAs with an unsaturated fatty acid but not with a saturated fatty acid induced an increase in the [Ca(2+)](i) of EDG7-expressing Sf9 cells, whereas LPAs with both saturated and unsaturated fatty acids elicited a Ca(2+) response in Sf9 cells expressing EDG4. In EDG7- or EDG4-expressing Sf9 cells, LPA stimulated forskolin-induced increase in intracellular cAMP levels, which was not observed in EDG2-expressing cells. In PC12 cells, EDG4 but not EDG2 or EDG7 mediated the activation of MAP kinase by LPA. Neither the EDG7- nor EDG4-transduced Ca(2+) response or cAMP accumulation was inhibited by pertussis toxin. In conclusion, the present study demonstrates that EDG7, a new member of the EDG family of G-protein-coupled receptors, is a specific LPA receptor that shows distinct properties from known cloned LPA receptors in ligand specificities, Ca(2+) response, modulation of adenylyl cyclase, and MAP kinase activation.
Bandoh
K
K
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Aoki
J
J
Hosono
H
H
Kobayashi
S
S
Kobayashi
T
T
Murakami-Murofushi
K
K
Tsujimoto
M
M
Arai
H
H
Inoue
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008246:Lysophospholipids / Q000378:metabolism*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D016716:PC12 Cells; D010802:Phylogeny; D015221:Potassium Channels / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D051381:Rats; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera; D014157:Transcription Factors; D014162:Transfection; D050807:ets-Domain Protein Elk-1
D017931:DNA Primers; D004268:DNA-Binding Proteins; C494114:Elk1 protein, rat; D008246:Lysophospholipids; D015221:Potassium Channels; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D011994:Recombinant Proteins; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D002118:Calcium