Homologous desensitisation of the mouse leukotriene B4 receptor involves protein kinase C-mediated phosphorylation of serine 127.

Jens Mollerup, Heidi N Eriksen, Janni Albertsen, Tune Wulff, Ian H Lambert, Else K Hoffmann

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Abstract

Murine leukotriene B(4) (LTB(4)) receptor (mBLT1) cDNA was identified by searching the EST database using human LTB(4) receptor as the query sequence. Expression of functional mBLT1 after injection of in vitro transcribed cRNA into Xenopus laevis oocytes was demonstrated as LTB(4)-evoked, Ca(2+)-activated Cl(-) currents recorded by two-electrode voltage clamp. From mBLT1-expressing oocytes, a dose-dependent relationship between the Ca(2+)-activated Cl(-) current and LTB(4) concentration was demonstrated with an apparent EC(50) of 6.7 nM. Following LTB(4) stimulation of mBLT1, we observed two transient, spatially distinct Ca(2+)-activated, inwardly directed Cl(-) currents in the oocytes: a fast peak current requiring relatively high LTB(4) concentrations, and a slowly progressing Cl(-) current. Nucleotides, PGE(2), 12R-hydroxy-5, 8, 14-cis-10-trans-eicosatetraenoic acid, and LTD(4) did not activate mBLT1. U75302, specifically targeting BLT1, significantly reduced LTB(4)-evoked Cl(-) currents. Repetitive LTB(4) administration desensitized the LTB(4)-evoked currents. Activation of protein kinase C (PKC) by PMA addition completely eliminated the LTB(4)-evoked currents, whereas down-regulation of PKC by prolonged PMA exposure (20 h) impaired mBLT1 desensitisation. In addition, Ser-127-Ala substitution of the PKC consensus phosphorylation site on the second intracellular loop prevented the mBLT1 desensitisation. These data indicate that PKC-mediated phosphorylation at Ser-127 leads to mBLT1 desensitisation.
Original languageEnglish
JournalCellular Physiology and Biochemistry
Volume20
Issue number1-4
Pages (from-to)143-56
Number of pages13
ISSN1015-8987
DOIs
Publication statusPublished - 2007

Bibliographical note

Keywords: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Amino Acid Sequence; Animals; Enzyme Activation; Fatty Alcohols; Female; Glycols; Leukotriene B4; Mice; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Oocytes; Pertussis Toxin; Phosphorylation; Protein Kinase C; Receptors, Leukotriene B4; Recombinant Proteins; Sequence Homology, Amino Acid; Serine; Signal Transduction; Tetradecanoylphorbol Acetate; Triterpenes

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