title: Endothelial cell palmitoylproteomic identifies novel lipid-modified targets and potential substrates for protein acyl transferases.
abstract: BACKGROUND
  Protein S-palmitoylation is the posttranslational attachment of a saturated 16-carbon palmitic acid to a cysteine side chain via a thioester bond. Palmitoylation can affect protein localization, trafficking, stability, and function. The extent and roles of palmitoylation in endothelial cell (EC) biology is not well-understood, partly because of technological limits on palmitoylprotein detection.
  
  
  OBJECTIVE
  To develop a method using acyl-biotinyl exchange technology coupled with mass spectrometry to globally isolate and identify palmitoylproteins in ECs.
  
  
  RESULTS
  More than 150 putative palmitoyl proteins were identified in ECs using acyl-biotinyl exchange and mass spectrometry. Among the novel palmitoylproteins identified is superoxide dismutase-1, an intensively studied enzyme that protects all cells from oxidative damage. Mutation of cysteine-6 prevents palmitoylation, leads to reduction in superoxide dismutase-1 activity in vivo and in vitro, and inhibits nuclear localization, thereby supporting a functional role for superoxide dismutase-1 palmitoylation. Moreover, we used acyl-biotinyl exchange to search for substrates of particular protein acyl transferases in ECs. We found that palmitoylation of the cell adhesion protein platelet endothelial cell adhesion molecule-1 is dependent on the protein acyl transferase ZDHHC21. We show that knockdown of ZDHHC21 leads to reduced levels of platelet endothelial cell adhesion molecule-1 at the cell surface.
  
  
  CONCLUSIONS
  Our data demonstrate the utility of EC palmitoylproteomics to reveal new insights into the role of this important posttranslational lipid modification in EC biology.
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Ethan P
authors.initials: EP
authors.lastname: Marin
authors.forename: Behrad
authors.initials: B
authors.lastname: Derakhshan
authors.forename: TuKiet T
authors.initials: TT
authors.lastname: Lam
authors.forename: Alberto
authors.initials: A
authors.lastname: Davalos
authors.forename: William C
authors.initials: WC
authors.lastname: Sessa
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology*; D057809:HEK293 Cells; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D054878:Lipoylation / Q000502:physiology*; D008969:Molecular Sequence Data; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D034741:RNA, Small Interfering / Q000235:genetics; D013379:Substrate Specificity; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1; D034741:RNA, Small Interfering; C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000217:Acyltransferases; C571412:ZDHHC21 protein, human; D000123:Acetyltransferases; C062782:protein acyltransferase