Phagocytic signaling molecules in lipid rafts of COS-1 cells transfected with FcγRIIA

Pamela J. Mansfield, Vania Hinkovska-Galcheva, Michael S. Borofsky, James A. Shayman, Laurence A. Boxer

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

COS-1 cells bearing FcγRIIA were used as a model to demonstrate co-localization of several enzymes previously shown to regulate neutrophil phagocytosis. In COS-1 cells, phospholipase D (PLD) in the membrane fraction was activated during phagocytosis. PLD was found almost exclusively in lipid rafts, along with RhoA and ARF1. Protein kinase C-δ (PKCδ) and Raf-1 translocated to lipid rafts. In neutrophils, ceramide levels increase during phagocytosis, indicating that FcγRIIA engagement initiates ceramide generation. Applying this model, we transfected COS-1 cells with FcγRIIA that had been mutated in the ITAM region, rendering them unable to ingest particles. When the mutant receptors were engaged, ceramide was generated and MAPK was activated normally, thus these processes did not require actual ingestion of particles. These results indicate that signaling proteins for phagocytosis are either constitutively present in, or are recruited to, lipid rafts where they are readily available to activate one another.

Original languageEnglish (US)
Pages (from-to)132-138
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume331
Issue number1
DOIs
StatePublished - May 27 2005

Keywords

  • Cell activation
  • Fc receptors
  • Phagocytosis
  • Signal transduction

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