title: Three-dimensional architecture of the thymus is required to maintain delta-like expression necessary for inducing T cell development.
abstract: The three-dimensional microarchitecture of the thymus plays a unique role in directing T cell lineage commitment and development. This is supported by the fact that, in contrast to fetal thymic organ cultures, thymic stromal cell monolayer cultures (TSMC) fail to support T lymphopoiesis. Nevertheless, OP9-DL1 cell monolayer cultures induce T lineage commitment and differentiation. Thus, the inability of TSMC to support T lymphopoiesis may be due to a loss of Notch ligand expression and/or function during culture. In this study, we report that, in contrast to fetal thymic organ cultures, TSMC fail to maintain expression of the Notch ligands, Delta-like (Dll) 1 and Dll4, and concomitantly lose the ability to support T lymphopoiesis. Importantly, ectopic re-expression of Dll1 or Dll4 is sufficient to restore the ability of TSMC to support T lymphopoiesis. These findings demonstrate that maintenance of endogenous Dll1 or Dll4 expression by thymic stromal cells is required for the commitment and differentiation of T cells in the absence of a three-dimensional microenvironment.
authors.affiliation: Department of Immunology, University of Toronto, and Sunnybrook & Women's Research Institute, Toronto, Ontario, Canada.
authors.forename: Mahmood
authors.initials: M
authors.lastname: Mohtashami
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Zúñiga-Pflücker
mesh_terms: D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D038041:Lymphopoiesis; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D011247:Pregnancy; D012097:Repressor Proteins / Q000235:genetics; D017154:Stromal Cells / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology* / Q000276:immunology*
chemical_list: D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; C512925:Dlk1 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D012097:Repressor Proteins; C064045:delta protein