Characterization of a Receptor Subtype-Selective Lysophosphatidic Acid Mimetic
- Shelley B. Hooks4,
- Seamus P. Ragan3,
- Darrin W. Hopper2,
- Christian W. Hönemann1,
- Marcel E. Durieux1,3,
- Timothy L. Macdonald2 and
- Kevin R. Lynch3,4
- Departments of 1Anesthesiology (C.W.H., M.E.D.), 2Chemistry (D.W.H., T.L.M.), 3Pharmacology (S.P.R., M.E.D., K.R.L.), and 4Biochemistry (S.B.H., K.R.L), University of Virginia, Charlottesville, Virginia 22908
Abstract
Despite an intriguing cell biology and the suggestion of a role in pathophysiological responses, the mechanism of action of such lipid phosphoric acid mediators as lysophosphatidic acid (LPA) remains obscure, in part because of an underdeveloped medicinal chemistry. We report now the agonist activity of a synthetic phospholipid in which the glycerol backbone of LPA is replaced by l-serine. Like LPA, the l-serine-based lipid mobilizes calcium and inhibits activation of adenylyl cyclase in the human breast cancer cell line MDA MB231. Treatment with LPA desensitizes MDA MB231 cells to subsequent application of the l-serine compound; when the order of application is reversed, however, the l-serine compound does not prevent calcium mobilization by LPA, which might indicate the existence of two LPA receptors in these cells. The analogous d-serine-based phospholipid was distinctly less potent than the l-isomer in those assays; this finding demonstrates stereoselectivity by an LPA receptor. Unlike LPA, thel-serine-based lipid does not evoke a chloride conductance in Xenopus laevis oocytes, but injection of poly(A)+ RNA from HEK 293 cells confers this phenotype on the oocyte. The latter result has practical importance in that it allows use of the frog oocyte for expression cloning of an LPA receptor DNA, an assay system made problematic by the oocyte’s strong endogenous response to LPA.
Footnotes
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Send reprint requests to: Kevin R. Lynch, Ph.D., Dept. of Pharmacology, Box 448, University of Virginia Health Sciences Center, 1300 Jefferson Park Ave., Charlottesville, VA 22908. E-mail:krl2z{at}virginia.edu
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This work was supported by grants from the National Institute of General Medical Sciences: R01-GM52722 (K.R.L., T.L.M.), R29-GM52387 (M.E.D.), and T32-GM08136, predoctoral traineeship (S.B.H.). C.H. is supported by Innovative Medizinische Forschung, HO-1–6-11/96–8.
- Abbreviations:
- LPA
- lysophosphatidic acid
- NOEPA
- N-oleoyl ethyl phosphoric acid
- NASPA
- N-acyl serine phosphoric acid
- TRAP
- thrombin receptor activating peptide
- HPLC
- high performance liquid chromatography
- BSA
- bovine serum albumin
- HEK
- human embryonic kidney
- ICl(Ca)
- calcium-induced chloride current
- EDG-2
- endothelin differentiation gene-2
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- Received August 12, 1997.
- Accepted October 27, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
