title: Progression of T cell lineage restriction in the earliest subpopulation of murine adult thymus visualized by the expression of lck proximal promoter activity.
abstract: The proximal promoter of lck directs gene expression exclusively in T cells. To investigate the developmental regulation of the lck proximal promoter activity and its relationship to T cell lineage commitment, a green fluorescence protein (GFP) transgenic (Tg) mouse in which the GFP expression is under the control of the proximal promoter of lck was created. In the adult GFP-Tg mice, >90% of CD4(+)CD8(+) and CD4(+)CD8(-) thymocytes, and the majority of CD4(-)CD8(+) and CD4(-)CD8(-) [double-negative (DN)] thymocytes were highly positive for GFP. Slightly lower but substantial levels of expression of GFP was also observed in mature splenic T cells. No GFP(+) cells was detected in non-T lineage subsets, including mature and immature B cells, CD5(+) B cells, and NK cells, indicating a preserved tissue specificity of the promoter. The earliest GFP(+) cells detected were found in the CD44(+)CD25(-) DN thymocyte subpopulation. The developmental potential of GFP(-) and GFP(+) cells in the CD44(+)CD25(-) DN fraction was examined using in vitro culture systems. The generation of substantial numbers of alphabeta and gammadelta T cells as well as NK cells was demonstrated from both GFP(-) and GFP(+) cells. However, no development of B cells or dendritic cells was detected from GFP(+) CD44(+)CD25(-) DN thymocytes. These results suggest that the progenitors expressing lck proximal promoter activity in the CD44(+)CD25(-) DN thymocyte subset have lost most of the progenitor potential for the B and dendritic cell lineage. Thus, progression of T cell lineage restriction in the earliest thymic population can be visualized by lck proximal promoter activity, suggesting a potential role of Lck in the T cell lineage commitment.
authors.affiliation: CREST (Core Research for Evolution Science and Technology) Project, Japan Science and Technology Corporation (JST), and Department of Molecular Immunology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Shimizu
authors.forename: H
authors.initials: H
authors.lastname: Kawamoto
authors.forename: M
authors.initials: M
authors.lastname: Yamashita
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: E
authors.initials: E
authors.lastname: Kondou
authors.forename: Y
authors.initials: Y
authors.lastname: Kaneko
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.forename: T
authors.initials: T
authors.lastname: Tokuhisa
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
authors.forename: M
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Katsura
authors.forename: T
authors.initials: T
authors.lastname: Nakayama
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology; D005786:Gene Expression Regulation / Q000276:immunology; D049452:Green Fluorescent Proteins; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000166:cytology / Q000378:metabolism; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000096:biosynthesis* / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D011401:Promoter Regions, Genetic / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000096:biosynthesis; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D037401:Scyphozoa; D013154:Spleen / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology* / Q000201:enzymology* / Q000254:growth & development / Q000276:immunology
chemical_list: D018960:Hyaluronan Receptors; D008164:Luminescent Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015375:Receptors, Interleukin-2; D049452:Green Fluorescent Proteins; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)