Lysophosphatidic acid receptor LPA1 trafficking and interaction with Rab proteins, as evidenced by Forster resonance energy transfer

LPA1 internalization to endosomes was studied employing Fo center dot rster Resonance Energy Transfer (FRET) in cells coexpressing the mCherry-lysophosphatidic acid LPA1 receptors and distinct eGFP-tagged Rab proteins. Lyso-phosphatidic acid (LPA)-induced internalization was rapid and decreased afterward: phorbol myristate acetate (PMA) action was slower and sustained. LPA stimulated LPA1-Rab5 interaction rapidly but transiently, whereas PMA action was rapid but sustained. Expression of a Rab5 dominant-negative mutant blocked LPA1-Rab5 interaction and receptor internalization. LPA-induced LPA1-Rab9 interaction was only observed at 60 min, and LPA1-Rab7 interaction after 5 min with LPA and after 60 min with PMA. LPA triggered immediate but transient rapid recycling (i.e., LPA1-Rab4 interaction), whereas PMA action was slower but sustained. Agonist-induced slow recycling (LPA1-Rab11 interaction) increased at 15 min and remained at this level, whereas PMA action showed early and late peaks. Our results indicate that LPA1 receptor internalization varies with the stimuli.