Characterization of lymphocyte fibronectin.
In vitro cultured "activated" peripheral blood lymphocytes and T-cell lines synthesized a high-molecular-weight gelatin binding molecule (MW 500 kDa), whereas resting lymphocytes showed poor or negligible synthesis of the same component. Concanavalin A-mediated anchorage of the lymphocytes to a substratum potentiated synthesis of the high-molecular-weight molecule. Western blotting of the gelatin-binding lymphocyte molecule demonstrated reactivity with antibodies specific for human fibronectin. Furthermore, immunocytochemistry showed reactivity of anti-fibronectin antibodies with T-lymphocytes at the single-cell level. The lymphocyte-derived fibronectin was preferentially cell associated and relatively small amounts were present in the culture medium. RT-PCR of total RNA from CD4+ T-cells and the lymphoid T-cell line MOLT-4 showed that the most abundant species of fibronectin mRNA lacked the entire III CS exon encoding the alpha 4 beta 1 binding region LDV. Amplification of the III CS region from other T-cell lines revealed that these cells expressed several fibronectin mRNA isoforms most of which were lacking the LDV coding sequence. In conclusion, synthesis of fibronectin is demonstrated to occur in T-lymphocytes and to be regulated by signals which activate the cells.
Hauzenberger
D
D
Department of Clinical Immunology, Karolinska Institute, Huddinge Hospital, Sweden.
Martin
N
N
Johansson
S
S
Sundqvist
K G
KG
D000328:Adult; D017398:Alternative Splicing / Q000276:immunology; D000595:Amino Acid Sequence; D002448:Cell Adhesion / Q000235:genetics / Q000276:immunology; D005353:Fibronectins / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D008213:Lymphocyte Activation / Q000276:immunology; D008969:Molecular Sequence Data; D009842:Oligopeptides; D012322:RNA Precursors / Q000032:analysis; D013601:T-Lymphocytes / Q000737:chemistry* / Q000502:physiology
D005353:Fibronectins; D009842:Oligopeptides; D012322:RNA Precursors; C090763:leucyl-aspartyl-valine