Functional characterization of lysophosphatidic acid receptor 1 mutants identified in rat cancer tissues.
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 LPA1and P308S, I310T, and Y311H LPA1, respectively. Here, we examined the functions of these LPA1mutants. Compared with wild-type (WT) LPA1, F295S, P308S, and I310T LPA1showed decreased maximal responses in inhibition of cAMP formation, Ca2+mobilization, and cytoskeletal changes. Y311H LPA1failed to show LPA-induced cellular responses. However, these LPA1mutants were internalized in response to LPA exposure. Finally, while WT and F295S LPA1showed a similar, broad distribution throughout the cell, P308S, I310T, and Y311H LPA1displayed a restricted cellular distribution and co-localized with the endoplasmic reticulum. These data suggest that the LPA1mutants perturb LPA signaling in cancer tissues.
Division of Molecular Neurobiology, Department of Life Science, School of Science and Engineering, Kindai University, Higashiosaka, Japan.
Shoichi
S
Ishii
Division of Molecular Oncology, Department of Life Science, School of Science and Engineering, Kindai University, Higashiosaka, Japan.
Toshifumi
T
Tsujiuchi
Division of Molecular Neurobiology, Department of Life Science, School of Science and Engineering, Kindai University, Higashiosaka, Japan. Electronic address: nfukushima@life.kindai.ac.jp.
Nobuyuki
N
Fukushima
D020816:Amino Acid Motifs; D000818:Animals; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D015870:Gene Expression; D022781:Hepatocytes / Q000378:metabolism* / Q000648:ultrastructure; D008246:Lysophospholipids / Q000378:metabolism*; D009154:Mutation; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D000072417:Protein Domains; D051381:Rats; D049368:Receptors, Lysophosphatidic Acid / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
C000619668:Lpar1 protein, rat; D008246:Lysophospholipids; D049368:Receptors, Lysophosphatidic Acid; D000242:Cyclic AMP; C032881:lysophosphatidic acid; D002118:Calcium
Endoplasmic reticulum; Internalization; LPA(1); Lysophosphatidic acid; Mutant; NPXXY motif