| 1. |
- Johansson, Ellen, et al.
(author)
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Revising the embryonic origin of thyroid C cells in mice and humans
- 2015
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In: Development (Cambridge, England). - : The Company of Biologists. - 1477-9129 .- 0950-1991. ; 142:20, s. 3519-3528
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Journal article (peer-reviewed)abstract
- Current understanding infers a neural crest origin of thyroid C cells, the major source of calcitonin in mammals and ancestors to neuroendocrine thyroid tumors. The concept is primarily based on investigations in quail-chick chimeras involving fate-mapping of neural crest cells to the ultimobranchial glands that regulate Ca(2+) homeostasis in birds, reptiles, amphibians and fishes, but whether mammalian C cell development implicates a homologous ontogenetic trajectory has not been experimentally verified. With lineage tracing we now provide direct evidence that Sox17+ anterior endoderm is the only source of differentiated C cells and their progenitors in mice. In similarity with many gut endoderm derivatives embryonic C cells were found to co-express pioneer factors forkhead box (Fox) a1 and Foxa2 before neuroendocrine differentiation takes place. In the ultimobranchial body epithelium emerging from pharyngeal pouch endoderm in early organogenesis differential Foxa1/Foxa2 expression distinguished two spatially separated pools of C cell precursors with different growth properties. A similar expression pattern was recapitulated in medullary thyroid carcinoma cells in vivo consistent with a growth-promoting role of Foxa1. Contrasting embryonic precursor cells, C cell-derived tumor cells invading the stromal compartment down-regulated Foxa2 foregoing epithelial-mesenchymal transition designated by loss of E-cadherin; both Foxa2 and E-cadherin were re-expressed at metastatic sites. These findings revise mammalian C cell ontogeny, expand the neuroendocrine repertoire of endoderm, and redefine the boundaries of neural crest diversification. The data further underpin distinct functions of Foxa1 and Foxa2 in both embryonic and tumor development.
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| 2. |
- Westerlund, Jessica, 1977, et al.
(author)
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Expression of Islet1 in thyroid development related to budding, migration, and fusion of primordia.
- 2008
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In: Developmental dynamics : an official publication of the American Association of Anatomists. - : Wiley. - 1058-8388. ; 237:12, s. 3820-9
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Journal article (peer-reviewed)abstract
- The LIM homeodomain transcription factor Isl1 was investigated in mouse thyroid organogenesis. All progenitor cells of the midline thyroid diverticulum and lateral primordia (ultimobranchial bodies) expressed Isl1. This pattern persisted until the growing anlagen fused at embryonic day (E) 13.5. In Isl1 null mutants thyroid progenitors expressing Nkx2.1 and Pax8 were readily specified in the anterior endoderm but the size of the thyroid rudiment was reduced. In late development, only immature C-cells expressed Isl1. In the adult gland the number of Isl1+ cells was small compared with cells expressing calcitonin. Analysis of microarray profiles indicated a higher level of Isl1 expression in medullary thyroid carcinomas than in tumors derived from follicular cells. Together, these findings suggest that Isl1 may be a novel regulator of thyroid development before terminal differentiation of the endocrine cell types. Isl1 is an embryonic C-cell precursor marker that may be relevant also in cancer developed from the mature C-cell.
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