title: Origin of the ultimobranchial body cyst: T/ebp/Nkx2.1 expression is required for development and fusion of the ultimobranchial body to the thyroid.
abstract: The ultimobranchial body (UBB) is an outpocketing of the fourth pharyngeal pouch that fuses with the thyroid diverticulum, giving rise to calcitonin-producing C-cells. In this study, we demonstrate that the UBB is composed of two types of cells: one expressing T/ebp/Nkx2.1 and the other expressing p63. The former cell type, accounting for a majority of the UBB, requires T/ebp/Nkx2.1 for their survival. In contrast, the p63-positive cells, even in the absence of T/ebp/Nkx2.1 expression, can proliferate and give rise to a vesicular structure that is lined by a monolayer of p63-negative cells, surrounded by a cluster and/or single layer of p63-positive cells, displaying the basal/stem cell phenotype. T/ebp/Nkx2.1 haploinsufficiency causes abnormal fusion of the UBB with the thyroid diverticulum, which stays as a cluster of C-cells around the vesicular structure, similar to the one observed in mice null for T/ebp/Nkx2.1 expression. These results demonstrate that T/ebp/Nkx2.1 plays a role in the survival of UBB cells, their dissemination into the thyroid diverticulum, and the formation of UBB-derived vesicular structure.
authors.affiliation: Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kusakabe
authors.forename: Nobuo
authors.initials: N
authors.lastname: Hoshi
authors.forename: Shioko
authors.initials: S
authors.lastname: Kimura
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics; D013961:Thyroid Gland / Q000196:embryology* / Q000378:metabolism; D000074482:Thyroid Nuclear Factor 1; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D014460:Ultimobranchial Body / Q000196:embryology* / Q000378:metabolism
chemical_list: C000614414:Nkx2-1 protein, mouse; D009687:Nuclear Proteins; D010750:Phosphoproteins; D000074482:Thyroid Nuclear Factor 1; D015534:Trans-Activators; D014157:Transcription Factors; C486419:Trp63 protein, mouse