title: Ontogenesis of rat immune system: Proteasome expression in different cell populations of the developing thymus.
abstract: Immune proteasomes in thymus are involved in processing of self-antigens, which are presented by MHC class I molecules for rejection of autoreactive thymocytes in adults and probably in perinatal rats. The distribution of immune proteasome subunits LMP7 and LMP2 in thymic cells have been investigated during rat perinatal ontogenesis. Double immunofluorescent labeling revealed LMP7 and LMP2 in thymic epithelial and dendritic cells, as well as in CD68 positive cells - macrophages, monocytes - at all developmental stages. LMP2 and LMP7 were also detected by flow cytometry in almost all thymic CD90 lymphocytes through pre- and postnatal ontogenesis. Our results demonstrate that the immune proteasomes are expressed in all types of thymic antigen presenting cells during perinatal ontogenesis, suggesting the establishment of the negative selection in the thymus at the end of fetal life. The observation of the immune proteasome expression in T lymphocytes suggests their role in thymocyte differentiation besides antigen processing in thymus.
authors.affiliation: N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia.
authors.forename: Victoria I
authors.initials: VI
authors.lastname: Melnikova
authors.forename: Natalia P
authors.initials: NP
authors.lastname: Sharova
authors.forename: Elena V
authors.initials: EV
authors.lastname: Maslova
authors.forename: Svetlana N
authors.initials: SN
authors.lastname: Voronova
authors.forename: Liudmila A
authors.initials: LA
authors.lastname: Zakharova
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000938:Antigen-Presenting Cells / Q000166:cytology / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D000943:Antigens, Differentiation / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism; D003713:Dendritic Cells / Q000166:cytology / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D007107:Immune System / Q000196:embryology* / Q000254:growth & development*; D053538:Keratin-18 / Q000378:metabolism; D053539:Keratin-19 / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000276:immunology / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D018800:Thy-1 Antigens / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development*; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D015214:Antigens, Differentiation, Myelomonocytic; D003546:Cysteine Endopeptidases; D053538:Keratin-18; D053539:Keratin-19; D046988:Proteasome Endopeptidase Complex; D021122:Protein Subunits; D011506:Proteins; D018800:Thy-1 Antigens; C539355:CD68 protein, rat; D000097382:CD68 Molecule; C459465:OX-62 antigen, rat; C506159:PA28 protein, rat; C071313:LMP-2 protein; C077436:LMP7 protein