Identification of PECAM-1 association with sphingosine kinase 1 and its regulation by agonist-induced phosphorylation.
Sphingosine 1-phosphate (S1P) is a bioactive lipid mediator generated from sphingosine by sphingosine kinase (SPHK). S1P acts both extracellularly and intracellularly as a signaling molecule, although its intracellular targets are still undefined. Intracellular level of S1P is under strict regulatory control of SPHK regulation, S1P degradation, and S1P dephosphorylation. Therefore, clarifying the mechanisms regulating SPHK activity may help us understand when and where S1P is generated. In this study, we performed yeast two-hybrid screening to search for SPHK1a-binding molecules that may be involved in the regulation of the kinase localization or activity. Platelet endothelial cell adhesion molecule-1 (PECAM-1) was identified as a protein potentially associating with SPHK1a. Their association was confirmed by co-immunoprecipitation analysis using HEK293 cells overexpressing PECAM-1 and SPHK1a. Moreover, the kinase activity appeared to be reduced in stable PECAM-1-expressing cells. PECAM-1 is expressed on the cell surface of vascular cells, and several stimuli are known to induce phosphorylation of its tyrosine residues. We found that such phosphorylation attenuated its association with SPHK1a. This association/dissociation of SPHK with PECAM-1, regulated by the phosphorylated state of the membrane protein, may be involved in the control of localized kinase activity in certain cell types.
Department of Biomembrane and Biofunctional Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12, Nishi 6, Kita, Sapporo 60-0812, Japan.
Yu
Y
Fukuda
Yuki
Y
Aoyama
Atsushi
A
Wada
Yasuyuki
Y
Igarashi
D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014909:Wheat Germ Agglutinins; D000099157:Sphingosine Kinase
D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D019408:Platelet Endothelial Cell Adhesion Molecule-1; D013110:Sphingosine; D014909:Wheat Germ Agglutinins; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate