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Thymocyte maturation is regulated by the activity of the helix-loop-helix protein, E47.

Bain G, Quong MW, Soloff RS, Hedrick SM, Murre C - J. Exp. Med. (1999)

Bottom Line: Additionally, development of CD8 lineage T cells in an MHC class I-restricted TCR transgenic background is sensitive to the dosage of E47.Mice deficient for E47 display an increase in production of mature CD4 and CD8 lineage T cells.Furthermore, ectopic expression of an E2A inhibitor helix-loop-helix protein, Id3, promotes the in vitro differentiation of an immature T cell line.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of California, San Diego, La Jolla, California 92093, USA.

ABSTRACT
The E2A proteins, E12 and E47, are required for progression through multiple developmental pathways, including early B and T lymphopoiesis. Here, we provide in vitro and in vivo evidence demonstrating that E47 activity regulates double-positive thymocyte maturation. In the absence of E47 activity, positive selection of both major histocompatibility complex (MHC) class I- and class II-restricted T cell receptors (TCRs) is perturbed. Additionally, development of CD8 lineage T cells in an MHC class I-restricted TCR transgenic background is sensitive to the dosage of E47. Mice deficient for E47 display an increase in production of mature CD4 and CD8 lineage T cells. Furthermore, ectopic expression of an E2A inhibitor helix-loop-helix protein, Id3, promotes the in vitro differentiation of an immature T cell line. These results demonstrate that E2A functions as a regulator of thymocyte positive selection.

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Increased percentage of SP thymocytes in E2A- and E47-deficient mice. (A) Two-color flow cytometric analysis of thymocytes from 4–6-wk-old E2A- and E47-deficient mice and heterozygous littermates. Thymocytes were analyzed by staining with anti-CD8α and anti-CD4. The numbers in each quadrant indicate the percentage of thymocytes in that population. (B) The percentage of mature CD4+ (left) or CD8+ (right) thymocytes is plotted for eight to nine individual E2A- and E47-deficient mice and heterozygous controls. The horizontal bars indicate the average percentage of CD4+ or CD8+ thymocytes for each genotype.
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Figure 1: Increased percentage of SP thymocytes in E2A- and E47-deficient mice. (A) Two-color flow cytometric analysis of thymocytes from 4–6-wk-old E2A- and E47-deficient mice and heterozygous littermates. Thymocytes were analyzed by staining with anti-CD8α and anti-CD4. The numbers in each quadrant indicate the percentage of thymocytes in that population. (B) The percentage of mature CD4+ (left) or CD8+ (right) thymocytes is plotted for eight to nine individual E2A- and E47-deficient mice and heterozygous controls. The horizontal bars indicate the average percentage of CD4+ or CD8+ thymocytes for each genotype.

Mentions: Previous studies have established that mutant mice lacking both E12 and E47 exhibit abnormalities in thymocyte development 7. To generate sufficient numbers of mice to further characterize the T cell phenotype, we analyzed E47-deficient mice, which have a significantly lower rate of postnatal lethality compared with the E2A−/− mice 15. However, we note that the E47-deficient mice also express reduced levels of the E12 protein compared with control littermates 15. We analyzed thymocytes derived from 4–6-wk-old E2A- or E47-deficient mice for the expression of CD4 and CD8 by flow cytometry. Wild-type and E47 or E2A heterozygous mice had virtually identical thymic profiles (data not shown). However, E2A- and E47-deficient thymi showed significant decreases in the percentage of DP thymocytes compared with their heterozygous littermates (Fig. 1 A). In contrast, the proportions of both the CD4 and CD8 SP populations were increased an average of two- to threefold in the E2A- and E47-deficient thymi (Fig. 1A and Fig. B).


Thymocyte maturation is regulated by the activity of the helix-loop-helix protein, E47.

Bain G, Quong MW, Soloff RS, Hedrick SM, Murre C - J. Exp. Med. (1999)

Increased percentage of SP thymocytes in E2A- and E47-deficient mice. (A) Two-color flow cytometric analysis of thymocytes from 4–6-wk-old E2A- and E47-deficient mice and heterozygous littermates. Thymocytes were analyzed by staining with anti-CD8α and anti-CD4. The numbers in each quadrant indicate the percentage of thymocytes in that population. (B) The percentage of mature CD4+ (left) or CD8+ (right) thymocytes is plotted for eight to nine individual E2A- and E47-deficient mice and heterozygous controls. The horizontal bars indicate the average percentage of CD4+ or CD8+ thymocytes for each genotype.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195738&req=5

Figure 1: Increased percentage of SP thymocytes in E2A- and E47-deficient mice. (A) Two-color flow cytometric analysis of thymocytes from 4–6-wk-old E2A- and E47-deficient mice and heterozygous littermates. Thymocytes were analyzed by staining with anti-CD8α and anti-CD4. The numbers in each quadrant indicate the percentage of thymocytes in that population. (B) The percentage of mature CD4+ (left) or CD8+ (right) thymocytes is plotted for eight to nine individual E2A- and E47-deficient mice and heterozygous controls. The horizontal bars indicate the average percentage of CD4+ or CD8+ thymocytes for each genotype.
Mentions: Previous studies have established that mutant mice lacking both E12 and E47 exhibit abnormalities in thymocyte development 7. To generate sufficient numbers of mice to further characterize the T cell phenotype, we analyzed E47-deficient mice, which have a significantly lower rate of postnatal lethality compared with the E2A−/− mice 15. However, we note that the E47-deficient mice also express reduced levels of the E12 protein compared with control littermates 15. We analyzed thymocytes derived from 4–6-wk-old E2A- or E47-deficient mice for the expression of CD4 and CD8 by flow cytometry. Wild-type and E47 or E2A heterozygous mice had virtually identical thymic profiles (data not shown). However, E2A- and E47-deficient thymi showed significant decreases in the percentage of DP thymocytes compared with their heterozygous littermates (Fig. 1 A). In contrast, the proportions of both the CD4 and CD8 SP populations were increased an average of two- to threefold in the E2A- and E47-deficient thymi (Fig. 1A and Fig. B).

Bottom Line: Additionally, development of CD8 lineage T cells in an MHC class I-restricted TCR transgenic background is sensitive to the dosage of E47.Mice deficient for E47 display an increase in production of mature CD4 and CD8 lineage T cells.Furthermore, ectopic expression of an E2A inhibitor helix-loop-helix protein, Id3, promotes the in vitro differentiation of an immature T cell line.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of California, San Diego, La Jolla, California 92093, USA.

ABSTRACT
The E2A proteins, E12 and E47, are required for progression through multiple developmental pathways, including early B and T lymphopoiesis. Here, we provide in vitro and in vivo evidence demonstrating that E47 activity regulates double-positive thymocyte maturation. In the absence of E47 activity, positive selection of both major histocompatibility complex (MHC) class I- and class II-restricted T cell receptors (TCRs) is perturbed. Additionally, development of CD8 lineage T cells in an MHC class I-restricted TCR transgenic background is sensitive to the dosage of E47. Mice deficient for E47 display an increase in production of mature CD4 and CD8 lineage T cells. Furthermore, ectopic expression of an E2A inhibitor helix-loop-helix protein, Id3, promotes the in vitro differentiation of an immature T cell line. These results demonstrate that E2A functions as a regulator of thymocyte positive selection.

Show MeSH
Related in: MedlinePlus