Lysophosphatidic acid (LPA) receptors are activated differentially by biological fluids: Possible role of LPA-binding proteins in activation of LPA receptors

Kotaro Hama, Koji Bandoh, Yoshiyuki Kakehi, Junken Aoki, Hiroyuki Arai

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Lysophosphatidic acid (LPA) exerts multiple biological functions through G protein-coupled receptors (EDG2/LPA1, EDG4/LPA2, and EDG7/LPA3) and is present in serum where it is associated with albumin. In this study we examined LPA activity in various biological fluids by measuring the LPA-induced increase in the intracellular concentration of calcium ion in three types of Sf9 insect cells, each expressing one of the LPA receptors. Using this system, we found that EDG2 and EDG4, but not EDG7, were activated strongly by addition of incubated plasma. By contrast, LPA detected in seminal plasma, which contains a low concentration of albumin, selectively activated EDG7. After LPA in these samples was extracted and reconstituted, it activated all three receptors. We also found that serum albumin readily inhibits the activation of EDG7 but not the activation of EDG2 or EDG4. In addition, plasma from Nagase analbuminemic rats but not plasma from control Sprague-Dawley rats was found to strongly activate EDG7, although the plasma of these two types of rats contained equal amounts of LPA and activated both EDG2 and EDG4. The present study shows that serum albumin can negatively regulate EDG7 but not EDG2 or EDG4, and suggests that protein factors are present in seminal plasma and deliver LPA efficiently to EDG7 but not to EDG2 or EDG4.

Original languageEnglish
Pages (from-to)187-192
Number of pages6
JournalFEBS Letters
Volume523
Issue number1-3
DOIs
Publication statusPublished - 2002 Jul 17

Keywords

  • Albumin
  • EDG7
  • LPA3
  • Lysophosphatidic acid
  • Nagase analbuminemic rat
  • Seminal fluid

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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