Free fatty acid receptor 4 agonists induce lysophosphatidic acid receptor 1 (LPA ) desensitization independent of LPA internalization and heterodimerization.

The crosstalk between the free fatty acid receptor FFA4 and the lysophosphatidic acid receptor LPA seems to be of pathophysiological importance. We explored this crosstalk employing co-expression of fluorescent protein-tagged receptors. FFA4 activation induces functional desensitization of LPA receptors and phosphorylation of both receptors. LPA activation induces phosphorylation of LPA , but not of FFA4, and induces internalization of both receptors into heterogeneous types of vesicles. Docosahexaenoic acid (DHA) induces internalization of FFA4 but not of LPA . Fatty acid-induced FFA4-LPA interaction was observed using Förster resonance energy transfer and co-immunoprecipitation. Such interaction took place after desensitization was already established. Data indicate that FFA4 activation induces LPA desensitization in an internalization-independent process and that complex cellular processes participate in the crosstalk of these receptors.