Functional characterization of lysophosphatidic acid receptor 1 mutants identified in rat cancer tissues

Biochem Biophys Res Commun. 2017 May 6;486(3):767-773. doi: 10.1016/j.bbrc.2017.03.118. Epub 2017 Mar 23.

Abstract

Lysophosphatidic acid (LPA), an extracellular lipid mediator, exerts various cellular effects through activation of LPA receptors, LPA1-LPA6, in many types of cells including cancer cells. We recently found several missense mutations of Lpar1 in rat cancer tissues. One of these mutations is located at the extracellular tip of the seventh transmembrane domain of LPA1, and another three mutations are found within the NPXXY motif in the seventh transmembrane domain. These mutants are designated F295S LPA1 and P308S, I310T, and Y311H LPA1, respectively. Here, we examined the functions of these LPA1 mutants. Compared with wild-type (WT) LPA1, F295S, P308S, and I310T LPA1 showed decreased maximal responses in inhibition of cAMP formation, Ca2+ mobilization, and cytoskeletal changes. Y311H LPA1 failed to show LPA-induced cellular responses. However, these LPA1 mutants were internalized in response to LPA exposure. Finally, while WT and F295S LPA1 showed a similar, broad distribution throughout the cell, P308S, I310T, and Y311H LPA1 displayed a restricted cellular distribution and co-localized with the endoplasmic reticulum. These data suggest that the LPA1 mutants perturb LPA signaling in cancer tissues.

Keywords: Endoplasmic reticulum; Internalization; LPA(1); Lysophosphatidic acid; Mutant; NPXXY motif.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Calcium / metabolism
  • Cell Line, Tumor
  • Cyclic AMP / metabolism
  • Cytoskeleton / metabolism
  • Cytoskeleton / ultrastructure
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum / ultrastructure
  • Gene Expression
  • Hepatocytes / metabolism*
  • Hepatocytes / ultrastructure
  • Lysophospholipids / metabolism*
  • Mutation*
  • Neurons / metabolism*
  • Neurons / ultrastructure
  • Protein Domains
  • Rats
  • Receptors, Lysophosphatidic Acid / chemistry
  • Receptors, Lysophosphatidic Acid / genetics*
  • Receptors, Lysophosphatidic Acid / metabolism
  • Signal Transduction

Substances

  • Lpar1 protein, rat
  • Lysophospholipids
  • Receptors, Lysophosphatidic Acid
  • Cyclic AMP
  • lysophosphatidic acid
  • Calcium