title: Microenvironmental regulation of inducible nitric oxide synthase expression and nitric oxide production in mouse bone marrow-derived mast cells.
abstract: In addition to its well-known role in relaxation of vascular smooth muscle, NO modulates immune responses in a concentration- and location-specific manner. For MC, it is well accepted that exogenous NO regulates their function. However, there are inconsistencies in the literature of whether MC express NOS and make NO. MC progenitors mature in peripheral tissues, but the factors that influence MC maturation and their specific phenotype, such as whether they express NOS, are not well understood. To study microenvironmental conditions that could be "permissive" for NOS expression, we cultured BMMC in various conditions--BMMC(IL-3), BMMC(SCF/IL-3), or BMMC(SCF/IL-4)-for >3 weeks and examined NOS expression. We detected Nos2 mRNA in BMMC(SCF/IL-4) but not BMMC(IL-3) or BMMC(SCF/IL-3). After stimulation with IFN-γ and/or LPS, NOS2 expression and NO production were detected in BMMC(SCF/IL-4) but rarely detected in BMMC cultured with other conditions. Confocal microscopic analysis showed that NOS2 expression induced by IFN-γ colocalized in CD117(+) BMMC. NO production, after activation with IFN-γ and LPS in BMMC(SCF/IL-4), was abrogated by pretreatment with the NOS2-specific inhibitor. In addition to NOS2 expression, BMMC(SCF/IL-4) were distinguished from BMMC(IL-3) in heparin and MMCP expression. Thus, MC progenitors that develop in SCF + IL-4 can be induced to express NOS2 after receiving appropriate signals, such as IFN-γ, and subsequently produce NO. Microenvironmental conditions during their development can influence whether MC are capable of NOS expression and of NO production.
authors.affiliation: Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Tae Chul
authors.initials: TC
authors.lastname: Moon
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yoshimura
authors.forename: Thomas
authors.initials: T
authors.lastname: Parsons
authors.forename: A Dean
authors.initials: AD
authors.lastname: Befus
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology*; D016207:Cytokines / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000276:immunology; D008297:Male; D008407:Mast Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000096:biosynthesis / Q000276:immunology*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis / Q000276:immunology*; D019009:Proto-Oncogene Proteins c-kit / Q000276:immunology / Q000378:metabolism; D055153:Stem Cell Niche / Q000276:immunology*; D013234:Stem Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D013997:Time Factors
chemical_list: D016207:Cytokines; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D019009:Proto-Oncogene Proteins c-kit