title: Contact between human bone marrow stromal cells and B lymphocytes enhances very late antigen-4/vascular cell adhesion molecule-1-independent tyrosine phosphorylation of focal adhesion kinase, paxillin, and ERK2 in stromal cells.
abstract: Contact with bone marrow stromal cells is crucial for the normal growth and development of B-cell precursors. We have previously shown that human bone marrow stromal cell tyrosine kinase activity can be activated by direct contact with B-lymphoid cells (J Immunol 155:2359, 1995). In the present study, we show that increased tyrosine phosphorylation of focal adhesion kinase, paxillin, and extracellular-related kinase 2 (or p42 MAP kinase) accounted for the major changes occurring in stromal cell tyrosine phosphorylation after 5 to 10 minutes of contact with the RAMOS B-lymphoma cell line. Although adhesion of B-cell precursors to stromal cells is primarily mediated by very late antigen-4 (VLA-4) and vascular cell adhesion molecule-1 (VCAM-1), VLA-4-deficient and adhesion-deficient RAMOS cells were equally capable of stimulating stromal cell tyrosine phosphorylation. Similar changes in the tyrosine phosphorylation pattern of stromal cells were induced by contact with normal human B-cell precursors and several other B-lineage cell lines. After 5 to 30 minutes of contact with stromal cells, no change in protein tyrosine phosphorylation was detected in RAMOS or normal human B-cell precursors removed from stromal cells. Pretreatment of stromal cells with cytochalasin D abrogated contact-mediated enhancement of stromal cell tyrosine phosphorylation, suggesting that an intact cytoskeleton was essential. These results suggest that B-cell contact activates stromal cell signaling cascades that regulate cytoskeletal organization and transcription, independent of the interaction mediated by VLA-4 and VCAM-1.
authors.affiliation: Department of Laboratory Medicine/Pathology, Center for Immunology, University of Minnesota, Minneapolis, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Jarvis
authors.forename: J E
authors.initials: JE
authors.lastname: Maguire
authors.forename: T W
authors.initials: TW
authors.lastname: LeBien
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology*; D001854:Bone Marrow Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002450:Cell Communication; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000378:metabolism; D016393:Lymphoma, B-Cell / Q000201:enzymology / Q000473:pathology; D019950:Mitogen-Activated Protein Kinase 1; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology / Q000201:enzymology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*
chemical_list: D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D039041:Integrin alpha4beta1; D016023:Integrins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D016201:Receptors, Lymphocyte Homing; D019010:Vascular Cell Adhesion Molecule-1; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1