title: Internalization of factor J and cellular signalization after factor J-cell interaction.
abstract: Factor J (FJ) is a cationic glycoprotein with inhibitory activity in vitro against both classical and alternative pathways of complement activation. Recently FJ has been implicated in adhesion to several cell lines, through a membrane receptor identified as nucleolin. In the present work we study the events that follow the binding of FJ to cells. After incubation of K562 with FJ, this protein was internalized actively and localized in the cytoplasm and nucleus. Adhesion to immobilized FJ induced tyrosine phosphorylation of several intracellular proteins in Jurkat cell line with a similar pattern to that induced by fibronectin (FN), an extracellular matrix protein. This effect was maximal at 5 min and decreased after 10 min, and inhibited by anti-FJ monoclonal antibody (mAb). These results suggest that the binding of FJ to cells may play an important role in transduction of biochemical signals across the plasma membrane to the cell interior.
authors.affiliation: Unidad de Inmunología, Hospital La Paz, Madrid, 28046, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Larrucea
authors.forename: R
authors.initials: R
authors.lastname: Cambronero
authors.forename: C
authors.initials: C
authors.lastname: González-Rubio
authors.forename: B
authors.initials: B
authors.lastname: Fraile
authors.forename: C
authors.initials: C
authors.lastname: Gamallo
authors.forename: G
authors.initials: G
authors.lastname: Fontán
authors.forename: M
authors.initials: M
authors.lastname: López-Trascasa
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D003169:Complement Inactivator Proteins; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D004705:Endocytosis; D005353:Fibronectins / Q000378:metabolism; D005434:Flow Cytometry; D006023:Glycoproteins / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D008970:Molecular Weight; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
chemical_list: D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D003169:Complement Inactivator Proteins; D005353:Fibronectins; D006023:Glycoproteins; D011506:Proteins; C116021:factor J protein, human; D019000:Phosphotyrosine