Thyrotropin-independent induction of thyroid endoderm from embryonic stem cells by activin A.
To model the differentiation of thyroid epithelial cells, we examined embryoid bodies derived from undifferentiated murine embryonic stem cells treated with activin A to induce endoderm differentiation, the germ layer from which thyroid cells occur. The resulting endodermal cells were then further exposed to TSH and/or IGF-I for up to 21 d. Oct-4 and REX1 expression, required to sustain stem cell self-renewal and pluripotency, were appropriately down-regulated, whereas GATA-4, and alpha-fetoprotein, both endodermal-specific markers, increased as the embryonic stem cells were exposed to activin A. By d 5 culture, TSH receptor (TSHR) and sodium iodide symporter (NIS) gene and protein expression were markedly induced. Cells isolated by the fluorescence-activated cell sorter simultaneously expressed not only TSHR and NIS proteins but also PAX8 mRNA, an expression pattern unique to thyroid cells and expected in committed thyroid progenitor cells. Such expression continued until d 21 with no influence seen by the addition of TSH or IGF-I. The sequence of gene expression changes observed in these experiments demonstrated the emergence of definitive thyroid endoderm. The activin A induction of thyroid-specific markers, NIS and TSHR, occurred in the absence of TSH stimulation, and, therefore, the emergence of thyroid endoderm in vitro paralleled the emergence of thyroid cells in TSHR-knockout mice. Activin A is clearly a major regulator of thyroid endoderm.
Ma
Risheng
R
Thyroid Research Unit, Mount Sinai School of Medicine, James J. Peters Veterans Affairs Medical Center, New York,New York 10468, USA. risheng.ma@mssm.edu
Latif
Rauf
R
Davies
Terry F
TF
D028341:Activins / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology*; D004707:Endoderm / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D005434:Flow Cytometry; D050991:GATA4 Transcription Factor / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D051379:Mice; D050814:Octamer Transcription Factor-3 / Q000235:genetics; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics; D011989:Receptors, Thyrotropin / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027981:Symporters / Q000235:genetics; D013961:Thyroid Gland / Q000166:cytology*; D013972:Thyrotropin / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics; D000509:alpha-Fetoproteins / Q000235:genetics; D000099209:Sodium-Iodide Symporters
D028341:Activins; D050991:GATA4 Transcription Factor; D007334:Insulin-Like Growth Factor I; D050814:Octamer Transcription Factor-3; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors; D011989:Receptors, Thyrotropin; D027981:Symporters; D013972:Thyrotropin; D014157:Transcription Factors; D000509:alpha-Fetoproteins; D000099209:Sodium-Iodide Symporters; C499496:Pax8 protein, mouse; C513672:Zfp42 protein, mouse; C422405:activin A