Phosphotyrosine protein dynamics in cell membrane rafts of sphingosine-1-phosphate-stimulated human endothelium: Role in barrier enhancement

Jing Zhao, Patrick A. Singleton, Mary E. Brown, Steven M. Dudek, Joe G.N. Garcia

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Sphingosine-1-phosphate (S1P), a lipid growth factor, is critical to the maintenance and enhancement of vascular barrier function via processes highly dependent upon cell membrane raft-mediated signaling events. Anti-phosphotyrosine 2 dimensional gel electrophoresis (2-DE) immunoblots confirmed that disruption of membrane raft formation (via methyl-β-cyclodextrin) inhibits S1P-induced protein tyrosine phosphorylation. To explore S1P-induced dynamic changes in membrane rafts, we used 2-D techniques to define proteins within detergent-resistant cell membrane rafts which are differentially expressed in S1P-challenged (1 μM, 5 min) human pulmonary artery endothelial cells (EC), with 57 protein spots exhibiting > 3-fold change. S1P induced the recruitment of over 20 cell membrane raft proteins exhibiting increasing levels of tyrosine phosphorylation including known barrier-regulatory proteins such as focal adhesion kinase (FAK), cortactin, p85α phosphatidylinositol 3-kinase (p85αPI3K), myosin light chain kinase (nmMLCK), filamin A/C, and the non-receptor tyrosine kinase, c-Abl. Reduced expression of either FAK, MLCK, cortactin, filamin A or filamin C by siRNA transfection significantly attenuated S1P-induced EC barrier enhancement. Furthermore, S1P induced cell membrane raft components, p-caveolin-1 and glycosphingolipid (GM1), to the plasma membrane and enhanced co-localization of membrane rafts with p-caveolin-1 and p-nmMLCK. These results suggest that S1P induces both the tyrosine phosphorylation and recruitment of key actin cytoskeletal proteins to membrane rafts, resulting in enhanced human EC barrier function.

Original languageEnglish (US)
Pages (from-to)1945-1960
Number of pages16
JournalCellular Signalling
Issue number12
StatePublished - Dec 2009
Externally publishedYes


  • 2-DE
  • Cell membrane rafts
  • Endothelial cells
  • Mass spectrometry
  • Sphingosine 1-phosphate (S1P)

ASJC Scopus subject areas

  • Cell Biology


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