Phosphoproteomic analysis of Syk kinase signaling in human cancer cells reveals its role in cell-cell adhesion.
The spleen tyrosine kinase Syk has predominantly been studied in hematopoietic cells in which it is involved in immunoreceptor-mediated signaling. Recently, Syk expression was evidenced in numerous nonhematopoietic cells and shown to be involved in tumor formation and progression. The Syk downstream signaling effectors in nonhematopoietic cells remain, however, to be uncovered, and were investigated using MS-based quantitative phosphoproteomics. Two strategies, based on the inhibition of the Syk catalytic activity and on the loss of Syk expression were employed to identify phosphotyrosine-dependent complexes. Quantitative measurements were obtained on 350 proteins purified with phosphotyrosine affinity columns using the SILAC method. Forty-one proteins are dependent on both Syk expression and catalytic activity and were selected as signaling effectors. They are involved in a variety of biological processes such as signal transduction, cell-cell adhesion and cell polarization. We investigated the functional involvement of Syk in cell-cell adhesion and demonstrated the phosphorylation of E-cadherin and alpha-catenin. In addition, Syk is localized at cell-cell contacts, and Syk-mediated phosphorylation of E-cadherin seems to be important for the proper localization of p120-catenin at adherens junctions. Identification of the biochemical pathways regulated by Syk in human cancer cells will help to uncover its role in tumor formation and progression.
Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, IFR 122, Equipe Labellisée 2007 Ligue Nationale contre le Cancer, Universités Montpellier 1 and 2, Montpellier Cedex 5, France.
R M
RM
Larive
S
S
Urbach
J
J
Poncet
P
P
Jouin
G
G
Mascré
A
A
Sahuquet
P H
PH
Mangeat
P J
PJ
Coopman
N
N
Bettache
D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015820:Cadherins / Q000378:metabolism; D051177:Catenins; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D007365:Intercellular Junctions / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D000072377:Syk Kinase; D014162:Transfection; D000095002:Delta Catenin
D015820:Cadherins; D051177:Catenins; D015815:Cell Adhesion Molecules; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D000095002:Delta Catenin; C000722347:CTNND1 protein, human