title: Gene expression profile of the third pharyngeal pouch reveals role of mesenchymal MafB in embryonic thymus development.
abstract: The thymus provides a microenvironment that induces the differentiation of T-progenitor cells into functional T cells and that establishes a diverse yet self-tolerant T-cell repertoire. However, the mechanisms that lead to the development of the thymus are incompletely understood. We report herein the results of screening for genes that are expressed in the third pharyngeal pouch, which contains thymic primordium. Polymerase chain reaction (PCR)-based cDNA subtraction screening for genes expressed in microdissected tissues of the third pharyngeal pouch rather than the second pharyngeal arch yielded one transcription factor, MafB, which was predominantly expressed in CD45(-)IA(-)PDGFRalpha(+) mesenchymal cells and was detectable even in the third pharyngeal pouch of FoxN1-deficient nude mice. Interestingly, the number of CD45(+) cells that initially accumulated in the embryonic thymus was significantly decreased in MafB-deficient mice. Alterations of gene expression in the embryonic thymi of MafB-deficient mice included the reduced expression of Wnt3 and BMP4 in mesenchymal cells and of CCL21 and CCL25 in epithelial cells. These results suggest that MafB expressed in third pharyngeal pouch mesenchymal cells critically regulates lymphocyte accumulation in the embryonic thymus.
authors.affiliation: Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima, Japan.
authors.forename: Dil Afroz
authors.initials: DA
authors.lastname: Sultana
authors.forename: Shuhei
authors.initials: S
authors.lastname: Tomita
authors.forename: Michito
authors.initials: M
authors.lastname: Hamada
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Iwanaga
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kitahama
authors.forename: Nguyen Van
authors.initials: NV
authors.lastname: Khang
authors.forename: Shuichi
authors.initials: S
authors.lastname: Hirai
authors.forename: Izumi
authors.initials: I
authors.lastname: Ohigashi
authors.forename: Sachiko
authors.initials: S
authors.lastname: Nitta
authors.forename: Takashi
authors.initials: T
authors.lastname: Amagai
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Takahama
mesh_terms: D000818:Animals; D001934:Branchial Region / Q000378:metabolism*; D049109:Cell Proliferation; D004622:Embryo, Mammalian; D005260:Female; D020869:Gene Expression Profiling; D015723:Gene Library; D005796:Genes; D008214:Lymphocytes / Q000502:physiology; D051258:MafB Transcription Factor / Q000235:genetics / Q000502:physiology*; D008648:Mesoderm / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D008954:Models, Biological; D011247:Pregnancy; D013950:Thymus Gland / Q000196:embryology* / Q000276:immunology / Q000378:metabolism
chemical_list: D051258:MafB Transcription Factor; C490406:Mafb protein, mouse