title: Coordination between CCR7- and CCR9-mediated chemokine signals in prevascular fetal thymus colonization.
abstract: Thymus seeding by T-lymphoid progenitor cells is a prerequisite for T-cell development. However, molecules guiding thymus colonization and their roles before and after thymus vascularization are unclear. Here we show that mice doubly deficient for chemokine receptors CCR7 and CCR9 were defective specifically in fetal thymus colonization before, but not after, thymus vascularization. The defective prevascular fetal thymus colonization was followed by selective loss of the first wave of T-cell development generating epidermal Vgamma3(+) gammadelta T cells. Unexpectedly, CCL21, a CCR7 ligand, was expressed not by Foxn1-dependent thymic primordium but by Gcm2-dependent parathyroid primordium, whereas CCL25, a CCR9 ligand, was predominantly expressed by Foxn1-dependent thymic primordium, revealing the role of the adjacent parathyroid in guiding fetal thymus colonization. These results indicate coordination between Gcm2-dependent parathyroid and Foxn1-dependent thymic primordia in establishing CCL21/CCR7- and CCL25/CCR9-mediated chemokine guidance essential for prevascular fetal thymus colonization.
authors.affiliation: Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan.
authors.forename: Cunlan
authors.initials: C
authors.lastname: Liu
authors.forename: Fumi
authors.initials: F
authors.lastname: Saito
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Lei
authors.forename: Shoji
authors.initials: S
authors.lastname: Uehara
authors.forename: Paul
authors.initials: P
authors.lastname: Love
authors.forename: Martin
authors.initials: M
authors.lastname: Lipp
authors.forename: Shunzo
authors.initials: S
authors.lastname: Kondo
authors.forename: Nancy
authors.initials: N
authors.lastname: Manley
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Takahama
mesh_terms: D000818:Animals; D054421:Chemokine CCL21; D019742:Chemokines, CC / Q000378:metabolism; D005260:Female; D051858:Forkhead Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D018919:Neovascularization, Physiologic; D011247:Pregnancy; D054388:Receptors, CCR; D054400:Receptors, CCR7; D019707:Receptors, Chemokine / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013950:Thymus Gland / Q000098:blood supply / Q000196:embryology* / Q000276:immunology*
chemical_list: C119309:CC chemokine receptor 9; C515479:Ccl21c protein, mouse; C491541:Ccl25 protein, mouse; C515371:Ccr7 protein, mouse; D054421:Chemokine CCL21; D019742:Chemokines, CC; D051858:Forkhead Transcription Factors; D054388:Receptors, CCR; D054400:Receptors, CCR7; D019707:Receptors, Chemokine; C090140:Whn protein