Different mechanisms regulate lysophosphatidic acid (LPA)-dependent versus phorbol ester-dependent internalization of the LPA1 receptor.
Lysophosphatidic acid (LPA) stimulates cells by activation of five G-protein-coupled receptors, termed LPA 1-5. The LPA 1 receptor is the most widely expressed and is a major regulator of cell migration. In this study, we show that phorbol ester (PMA)-induced internalization of the LPA(1) receptor requires clathrin AP-2 complexes, protein kinase C, and a distal dileucine motif (amino acids 352 and 353) in the cytoplasmic tail but not beta-arrestin. Agonist-dependent internalization of LPA 1, however, requires a cluster of serine residues (amino acids 341-347) located proximal to the dileucine motif, beta-arrestin, and to a lesser extent clathrin AP-2. The serine cluster of LPA 1 is required for beta-arrestin2-GFP translocation to the plasma membrane and signal desensitization. In contrast, the dileucine motif (IL) is required for both basal and PMA-induced internalization. Evidence for the beta-arrestin independence of PMA-induced internalization of LPA 1 comes from the observations that beta-arrestin2-GFP is not recruited to the plasma membrane upon PMA treatment and that LPA 1 is readily internalized in beta-arrestin1/2 knock-out mouse embryonic fibroblasts. These results indicate that distinct molecular mechanisms regulate agonist-dependent and PMA-dependent internalization of the LPA 1 receptor.
Urs
Nikhil M
NM
School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Kowalczyk
Andrew P
AP
Radhakrishna
Harish
H
D033962:Adaptor Protein Complex 2 / Q000235:genetics / Q000378:metabolism; D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism; D002273:Carcinogens / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D049368:Receptors, Lysophosphatidic Acid / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D000071557:beta-Arrestins
D033962:Adaptor Protein Complex 2; D019390:Arrestins; D002273:Carcinogens; D002966:Clathrin; D008246:Lysophospholipids; D049368:Receptors, Lysophosphatidic Acid; D000071557:beta-Arrestins; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; C032881:lysophosphatidic acid