title: The CD19/CD81 complex physically interacts with CD38 but is not required to induce proliferation in mouse B lymphocytes.
abstract: In B lymphocytes, the cell surface receptor CD38 is involved in apoptosis of immature B cells, proliferation and differentiation of mature B cells. Although CD38 has been establish as a receptor, its signaling has been only partially characterized. As a result of the lack of signaling motifs in the cytoplasmic domain, CD38 must use a co-receptor to induce signaling within the cell. Accordingly, CD38 has been associated with different receptors such as the T-cell receptor/CD3 complex on T cells, CD16 on natural killer cells and MHC class II molecules on monocytes. The CD19/CD81 complex has been proposed as a co-receptor for CD38 in human B lymphocytes, but little or no characterization has been performed in mice. In this study the contribution of the CD19/CD81 complex in murine CD38 signaling was evaluated. Proliferation assays were performed using CD19(-/-)  or CD81(-/-)  deficient mice; CFSE-labeled B lymphocytes from wild-type mice and CD19(-/-) , CD81(-/-)  and CD38(-/-)  deficient mice were stimulated with agonistic antibodies against CD38. Immunoprecipitation and immunofluorescence were also performed to detect protein-protein interactions. Our results indicate that the CD19/CD81 complex interacts with CD38 but this interaction is not required to induce proliferation in mouse B lymphocytes, suggesting that other receptors may contribute to the proliferation induced by CD38 in B lymphocytes.
authors.affiliation: Departamento De Biomedicina Molecular, CINVESTAV-IPN, Mexico, D.F., Mexico.
authors.forename: Felipe
authors.initials: F
authors.lastname: Vences-Catalán
authors.forename: Ranjani
authors.initials: R
authors.lastname: Rajapaksa
authors.forename: Shoshana
authors.initials: S
authors.lastname: Levy
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Santos-Argumedo
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D018941:Antigens, CD19 / Q000235:genetics / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002450:Cell Communication; D049109:Cell Proliferation; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015398:Signal Transduction; D060225:Tetraspanin 28 / Q000235:genetics / Q000378:metabolism*
chemical_list: D018941:Antigens, CD19; D008565:Membrane Proteins; D060225:Tetraspanin 28; D051997:ADP-ribosyl Cyclase 1