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Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays
Published on: June 9, 2015
T cell development from kit-negative progenitors in the Foxn1Delta/Delta mutant thymus
Shiyun Xiao1, Dong-ming Su, Nancy R Manley
1Department of Genetics, Coverdell Center, University of Georgia, Athens, GA 30602, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|January 8, 2008
Summary
The Foxn1Delta mutation impairs T cell development by affecting thymic epithelial cells, leading to atypical T cell progenitors and increased B cell development. This study clarifies the developmental block in T cell precursors within the mutant thymus.
Area of Science:
- Immunology
- Developmental Biology
- Genetics
Background:
- Foxn1Delta is a hypomorphic allele of the nude gene.
- It causes arrested thymic epithelial cell differentiation and abnormal thymic architecture.
- This leads to altered T cell development, with an apparent absence of double-negative 3 (DN3) cells in the adult thymus.
Purpose of the Study:
- To investigate the origin of the contradictory T cell development phenotype in Foxn1Delta/Delta mutants.
- To analyze fetal and adult double-negative (DN) cells in these mutants.
- To understand the role of thymic stroma in T cell and B cell development.
Main Methods:
- Analysis of fetal and adult double-negative (DN) cells in Foxn1Delta/Delta mutant mice.
- Assessment of hematopoietic progenitor differentiation potential within the mutant thymus.
- Examination of B cell development and Notch ligand expression in the adult stroma.
Main Results:
- Neither adult bone marrow-derived nor fetal liver cells could differentiate to DN2 or DN3 stages in the Foxn1Delta/Delta thymus.
- Thymopoiesis in the adult mutant thymus proceeds from CD117- atypical progenitors, with CD117+ DN1a cells being absent or blocked.
- The Foxn1Delta/Delta adult thymus preferentially supports B-1 cell development, correlating with reduced Notch ligand expression.
Conclusions:
- The Foxn1Delta mutation disrupts T cell development by altering progenitor differentiation pathways within the thymus.
- Atypical T cell progenitors can develop and contribute to the peripheral T cell pool despite the thymic defects.
- The adult Foxn1Delta/Delta thymus environment favors B cell development, suggesting a role for thymic stroma in lineage bias.
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