In contrast to agonist monoclonal antibodies, both C-terminal truncated form and full length form of Pleiotrophin failed to activate vertebrate ALK (anaplastic lymphoma kinase)?
Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase essentially and transiently expressed during development in specific regions of the central and peripheral nervous system. ALK expression persists at a lower level in the adult brain. Thus, it might play an important role in both the normal development and function of the nervous system. The nature of the cognate ligand of this receptor in vertebrates is still a matter of debate. Pleiotrophin and midkine have been proposed as ligands of ALK but several independent studies do not confirm this hypothesis. Interestingly, a recent study proposed that a C-terminal truncated form of Pleiotrophin (Pleiotrophin.15) and not the full length form (Pleiotrophin.18) promotes glioblastoma proliferation in an ALK-dependent fashion. These data were obviously a strong basis to conciliate the conflicting results so far reported in the literature. In the present study, we first purified to homogeneity the two forms of Pleiotrophin secreted by HEK 293 cells. In contrast to agonist monoclonal antibodies, both Pleiotrophin.15 and Pleiotrophin.18 failed to activate ALK in neuroblastoma and glioblastoma cells expressing this receptor. Thus, for our point of view, ALK is still an orphan receptor in vertebrates.
Mathivet
Thomas
T
INSERM, UMR-S 839, Institut du Fer à Moulin, 17 rue du Fer à Moulin, Paris, F-75005, France.
Mazot
Pierre
P
Vigny
Marc
M
D000077548:Anaplastic Lymphoma Kinase; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D016207:Cytokines / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005909:Glioblastoma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007700:Kinetics; D008024:Ligands; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D009447:Neuroblastoma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5 / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D016207:Cytokines; D008024:Ligands; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C066845:pleiotrophin; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5