Pulmonary endothelial cell barrier enhancement by sphingosine 1-phosphate. Roles for cortactin and myosin light chain kinase

Steven M. Dudek, Jeffrey R. Jacobson, Eddie T. Chiang, Konstantin G. Birukov, Peiyi Wang, Xi Zhan, Joe G.N. Garcia

Research output: Contribution to journalArticlepeer-review

239 Scopus citations


We recently reported the critical importance of Rac GTPase-dependent cortical actin rearrangement in the augmentation of pulmonary endothelial cell (EC) barrier function by sphingosine 1-phosphate (S1P). We now describe functional roles for the actin-binding proteins cortactin and EC myosin light chain kinase (MLCK) in mediating this response. Antisense down-regulation of cortactin protein expression significantly inhibits S1P-induced barrier enhancement in cultured human pulmonary artery EC as measured by transendothelial electrical resistance (TER). Immunofluorescence studies reveal rapid, Rac-dependent translocation of cortactin to the expanded cortical actin band following S1P challenge, where colocalization with EC MLCK occurs within 5 min. Adenoviral overexpression of a Rac dominant negative mutant attenuates TER elevation by S1P. S1P also induces a rapid increase in cortactin tyrosine phosphorylation (within 30 s) critical to subsequent barrier enhancement, since EC transfected with a tyrosine-deficient mutant cortactin exhibit a blunted TER response. Direct binding of EC MLCK to the cortactin Src homology 3 domain appears essential to S1P barrier regulation, since cortactin blocking peptide inhibits both S1P-induced MLC phosphorylation and peak S1P-induced TER values. These data support novel roles for the cytoskeletal proteins cortactin and EC MLCK in mediating lung vascular barrier augmentation evoked by S1P.

Original languageEnglish (US)
Pages (from-to)24692-24700
Number of pages9
JournalJournal of Biological Chemistry
Issue number23
StatePublished - Jun 4 2004
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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