title: Sck is expressed in endothelial cells and participates in vascular endothelial growth factor-induced signaling.
abstract: Sck, a member of the Shc family of cell signaling proteins, has only been studied in neuronal cells, though previous studies have demonstrated its expression in tissues other than brain. Using RT-PCR and RNase protection assays, we detected Sck mRNA expression in endothelial cells, and Sck protein was detected by Western blotting using polyclonal and monoclonal antibodies targeting the Sck CH1 domain. Immunohistochemistry protocols demonstrate that Sck is expressed in KDR and PECAM positive cells found in the mouse retina, mouse heart and human umbilical chord. Treatment of human umbilical vein endothelial (HUVE) cells with vascular endothelial growth factor (VEGF) leads to the recruitment of Sck to the KDR VEGF receptor and an enhanced Sck tyrosine phosphorylation. Sck is recruited to KDR tyrosine 1175, as co-immunoprecipitation of KDR and Sck is not observed in VEGF-treated porcine aortic endothelial cells expressing a receptor mutated at this autophosphorylation site. The Sck and Shc SH2 domains, and not the PTB domain, mediates its interactions with KDR, as recombinant Sck SH2 domain binds to a tyrosine phosphorylated KDR 1175-derived synthetic peptide, but not to a peptide synthesized without tyrosine phosphate. Recombinant PLCgamma SH2 domain also interacts with the phosphotyrosine 1175 containing peptide. VEGF-induced MAPK activation is dependent upon PLCgamma activity, and chimeric proteins consisting of the Shc or Sck SH2 domains fused with a cellular internalization sequence attenuated this activation. Taken together, these results demonstrate that Sck is expressed in vascular endothelial cells, and participates in VEGF-induced signal transduction.
authors.affiliation: Department of Medicine, Cardiology Division, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA.
authors.forename: Kirsty E
authors.initials: KE
authors.lastname: Ratcliffe
authors.forename: Qi
authors.initials: Q
authors.lastname: Tao
authors.forename: Burju
authors.initials: B
authors.lastname: Yavuz
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Stoletov
authors.forename: Simone C
authors.initials: SC
authors.lastname: Spring
authors.forename: Bruce I
authors.initials: BI
authors.lastname: Terman
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000502:physiology*; D006801:Humans; D008222:Lymphokines / Q000378:metabolism*; D051379:Mice; D009928:Organ Specificity; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071426:Src Homology 2 Domain-Containing, Transforming Protein 2; D013552:Swine; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016228:Endothelial Growth Factors; D008222:Lymphokines; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011506:Proteins; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; C099021:SHC2 protein, human; D055765:Shc Signaling Adaptor Proteins; C486295:Shc2 protein, mouse; D000071426:Src Homology 2 Domain-Containing, Transforming Protein 2; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor