Progression of T cell lineage restriction in the earliest subpopulation of murine adult thymus visualized by the expression of lck proximal promoter activity

• Published in: International immunology 2001-01, Vol.13 (1), p.105-117
• Main Authors: Shimizu, Chiori, Kawamoto, Hiroshi, Yamashita, Masakatsu, Kimura, Motoko, Kondou, Eisuke, Kaneko, Yoshikatsu, Okada, Seiji, Tokuhisa, Takeshi, Yokoyama, Minesuke, Taniguchi, Masaru, Katsura, Yoshimoto, Nakayama, Toshinori
• Format: Article
• Language: English
• Subjects: AGM aorta–gonad–mesonephros; Animals; APC allophycocyanin; B-Lymphocytes - cytology; B6 C57BL/6; Cell Differentiation - genetics; Cell Differentiation - immunology; Cell Lineage - genetics; Cell Lineage - immunology; Cells, Cultured; d.p.c. days post-coitum; Dendritic Cells - cytology; DN double-negative; DP double-positive; FCM flow cytometry; Gene Expression Regulation - immunology; GFP green fluorescence protein; GM-CSF granulocyte macrophage colony stimulating factor; green fluorescence protein; Green Fluorescent Proteins; HOS high oxygen submersion; Hyaluronan Receptors - biosynthesis; Killer Cells, Natural - cytology; Killer Cells, Natural - metabolism; lck gene; Lin lineage marker; LM littermate; Luminescent Proteins - biosynthesis; Luminescent Proteins - genetics; Lymphocyte Specific Protein Tyrosine Kinase p56(lck) - biosynthesis; Lymphocyte Specific Protein Tyrosine Kinase p56(lck) - genetics; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microscopy, Confocal; PE phycoerythrin; Promoter Regions, Genetic - immunology; Receptors, Antigen, T-Cell, alpha-beta - biosynthesis; Receptors, Antigen, T-Cell, gamma-delta - biosynthesis; Receptors, Interleukin-2 - biosynthesis; SCF stem cell factor; Scyphozoa; SP single-positive; Spleen - immunology; Spleen - metabolism; T cell lineage commitment; T-Lymphocyte Subsets - cytology; T-Lymphocyte Subsets - enzymology; T-Lymphocyte Subsets - immunology; T-Lymphocyte Subsets - metabolism; Tg transgenic; Thymus Gland - cytology; Thymus Gland - enzymology; Thymus Gland - growth & development; Thymus Gland - immunology; TN triple-negative; TNF tumor necrosis factor; transgenic
• ISSN: 0953-8178; 1460-2377
• DOI: 10.1093/intimm/13.1.105

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 αβ and γδ 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.