Cross-desensitization among receptors for platelet activating factor and peptide chemoattractants. Evidence for independent regulatory pathways.

Published

Journal Article

Cross-desensitization among receptors for peptide chemoattractants have been shown to involve two independent processes, receptor phosphorylation and inhibition of phospholipase C (PLC) activation. Receptors for lipid chemoattractants, i.e. platelet activating factor (PAF) and leukotriene B4, did not inhibit the responses of peptide chemoattractant receptors, suggesting distinct signaling pathways. To examine cross-desensitization between receptors for lipid and peptide chemoattractants, cDNA encoding the PAF receptor (PAFR) was co-expressed into RBL-2H3 cells with cDNAs encoding receptors for either formylated peptides (FR), a product of the fifth component of complement (C5aR) or interleukin-8 A (IL-8RA). PAFR was homologously phosphorylated and desensitized by PAF, and cross-phosphorylated and cross-desensitized by fMet-Leu-Phe, C5a, and IL-8. In contrast, the receptors for peptide chemoattractants were neither cross-phosphorylated nor cross-desensitized by PAF. Staurosporine blocked cross-phosphorylation and cross-desensitization of the PAFR by peptide chemoattractants. Truncation of the cytoplasmic tail of PAFR (mPAFR) abolished its homologous and cross-phosphorylation. mPAFR was also resistant to cross-desensitization by peptide chemoattractants at the level of PLC activation. Interestingly, mPAFR mediated a sustained Ca2+ mobilization in response to PAF and was more active in inducing GTPase activity, phosphoinositide hydrolysis, secretion, and phospholipase D activation than the wild type PAFR. In contrast to PAFR, stimulation of the mPAFR cross-phosphorylated and cross-desensitized responses to IL-8RA. As expected, FR, which is resistant to cross-phosphorylation by C5aR and IL-8RA, was not phosphorylated by mPAFR. However, unlike C5aR and IL-8RA, mPAFR did not inhibit the ability of FR to activate PLC. Blocking Ca2+ influx inhibited mPAFR-mediated sustained Ca2+ response, phospholipase D activation and secretion, but not phosphoinositide hydrolysis and cross-phosphorylation and cross-desensitization of IL-8RA. The data herein suggest that cross-desensitization of PAFR by peptide chemoattractants is solely due to receptor phosphorylation. The PAFR and the peptide chemoattractant receptors do not cross-regulate each other at the level of PLC, suggesting distinct regulatory pathways.

Full Text

Duke Authors

Cited Authors

  • Richardson, RM; Haribabu, B; Ali, H; Snyderman, R

Published Date

  • November 8, 1996

Published In

Volume / Issue

  • 271 / 45

Start / End Page

  • 28717 - 28724

PubMed ID

  • 8910508

Pubmed Central ID

  • 8910508

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.271.45.28717

Language

  • eng

Conference Location

  • United States