The lysophosphatidic acid receptor 1 (LPA1), a G-protein coupled receptor, regulates cell proliferation, migration, and cytokine release. Here, we investigate the molecular signature of LPA1 trafficking to the cell surface. The overexpressed LPA1 with a C-terminal V5 tag (LPA1-V5) is majorly expressed on the cell surface, while two deletion mutants (C320 and Delta 84-87) failed to be trafficked to the cell surface. Further, site-directed mutagenesis analysis of the LPA1 revealed that Ile325,Tyr85, and Leu87 within these two fragments regulate LPA1 maturation and trafficking to the cell surface. Over-expression of Sari, a component of coat protein complex 11 (COPII), enhances glycosylation of LPA1 wild type, but not these mutants. The mutants of LPA1 are majorly localized in the endoplasmic reticulum (ER) and exhibit a higher binding affinity to heat shock protein 70 (Hsp70), when compared to the LPA1 wild type. Further, we found that all these mutants failed to increase phosphorylation of Erk, and the cytokine release in response to LPA treatment. These results suggest that Ile325, Tyr85, and Leu87 within LPA1 are essential for LPA1 protein properly folding in the ER. (C) 2014 Elsevier Inc. All rights reserved.
[1]Univ Pittsburgh, Sch Med, Dept Med, Pittsburgh, PA 15213 USA.
[2]Univ Pittsburgh, Vasc & Med Inst, Pittsburgh, PA 15213 USA.
[3]Jilin Univ, Hosp 1, Dept Anesthesia, Changchun 130023, Peoples R China.
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