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Site-specific phosphorylation of CXCR4 is dynamically regulated by multiple kinases and results in differential

John M Busillo1, Sylvain Armando, Rajarshi Sengupta

  • 1Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

The Journal of Biological Chemistry
|January 6, 2010
PubMed

Insights

Phosphorylation of the chemokine receptor CXCR4 by various kinases dynamically regulates its signaling. Specific phosphorylation sites control distinct signaling pathways, impacting diseases like cancer and HIV.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pharmacology

Background:

  • The chemokine receptor CXCR4 is a G protein-coupled receptor implicated in diseases like HIV, cancer, and WHIM syndrome.
  • Dysregulation of CXCR4 signaling is linked to cancer and WHIM syndrome, highlighting the need to understand its regulation.

Purpose of the Study:

  • To investigate the role of phosphorylation in regulating CXCR4 signaling.
  • To identify specific sites of agonist-promoted CXCR4 phosphorylation and the kinases involved.

Main Methods:

  • Tandem mass spectrometry was used to identify phosphorylation sites.
  • Phospho-specific antibodies were employed to detect phosphorylated residues.
  • CXCR4 signaling was analyzed in HEK293 and human astroglia cells.

Main Results:

  • Seven sites on CXCR4 were identified as phosphorylated upon CXCL12 treatment, including Ser-324/5, Ser-330, and Ser-339.
  • Protein kinase C and GRK6 were identified as key kinases phosphorylating Ser-324/5, while GRK6 phosphorylated Ser-330 and Ser-339.
  • Different kinases and arrestins differentially regulated calcium mobilization and ERK1/2 activation.
  • Arrestin association was primarily mediated by phosphorylation of C-terminal residues.

Conclusions:

  • Site-specific phosphorylation of CXCR4 is dynamically regulated by multiple kinases.
  • Phosphorylation modulates CXCR4 signaling, leading to both positive and negative effects on cellular responses.
  • Understanding these phosphorylation events is crucial for targeting CXCR4 in disease.

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