title: Receptor-mediated down-regulation of neutral endopeptidase (NEP; EC 3.4.24.11; CD10) on immature B lymphocytes by dexamethasone.
abstract: Neutral endopeptidase is a membrane bound enzyme with various functions depending on cell type or tissue origin. Normal development and differentiation of immature B lymphocytes depends on expression of CD10/NEP on B cell progenitors and bone marrow stromal cells. Synthetic glucocorticoid dexamethasone (dex), an immunosuppressive and anti-inflammatory drug, was shown to be a potent modulator of CD10/NEP expressed on cells of non-hematopoietic origin. We investigated the effect of dex on expression of differentiation marker CD10/NEP on immature B cells. The drug was applied in concentrations corresponding to the physiological range. CD10/NEP was measured at three levels of expression: mRNA (by means of duplex PCR), membrane protein marker (FACS analysis) and enzyme activity (hydrolysis of a selective chromogenic substrate). Dex down-regulated CD10/NEP expression on immature B cell line NALM-6 in a concentration- and time-dependent fashion. The effect was detected at all three levels. Dex-induced CD10/NEP down-regulation was mediated via glucocorticoid receptors (GR), as it was fully abrogated by a GR antagonist, RU 38486. That occurred at all three levels. The mechanism of dex-induced CD10/NEP down-regulation is not likely to include selection of cells that are CD10low since the effect was partly reversible after the removal of dex. However, dex-induced CD10/NEP down-regulation did include decreased transcription of the CD10 mRNA. Transcriptional inhibitor actinomycin D completely abolished dex-induced CD10/NEP down-regulation. Since differentiation of normal B lymphocytes is associated with down-regulation of CD10/NEP, the data presented suggest that low, physiologically relevant concentrations of glucocorticoids (such as observed in acute stress) may play a regulatory role in normal development and maturation of B lymphocytes.
authors.affiliation: Rudjer Boskovic Institute, Division of Molecular Medicine, Laboratory for Experimental Hematology, Immunology and Oncology, HR-10 002 Zagreb, Croatia. bbuza@irb.hr
authors.forename: Barbara
authors.initials: B
authors.lastname: Cupic
authors.forename: Davorka
authors.initials: D
authors.lastname: Breljak
authors.forename: Jelka
authors.initials: J
authors.lastname: Gabrilovac
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D015415:Biomarkers; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D015260:Neprilysin / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
chemical_list: D000893:Anti-Inflammatory Agents; D015415:Biomarkers; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone; D015260:Neprilysin