Pendrin is a novel in vivo downstream target gene of the TTF-1/Nkx-2.1 homeodomain transcription factor in differentiated thyroid cells.
Thyroid transcription factor gene 1 (TTF-1) is a homeobox-containing gene involved in thyroid organogenesis. During early thyroid development, the homeobox gene Nkx-2.5 is expressed in thyroid precursor cells coincident with the appearance of TTF-1. The aim of this study was to investigate the molecular mechanisms underlying thyroid-specific gene expression. We show that the Nkx-2.5 C terminus interacts with the TTF-1 homeodomain and, moreover, that the expression of a dominant-negative Nkx-2.5 isoform (N188K) in thyroid cells reduces TTF-1-driven transcription by titrating TTF-1 away from its target DNA. This process reduced the expression of several thyroid-specific genes, including pendrin and thyroglobulin. Similarly, down-regulation of TTF-1 by RNA interference reduced the expression of both genes, whose promoters are sensitive to and directly associate with TTF-1 in the chromatin context. In conclusion, we demonstrate that pendrin and thyroglobulin are downstream targets in vivo of TTF-1, whose action is a prime factor in controlling thyroid differentiation in vivo.
Dentice
Monica
M
Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, 80131 Naples, Italy.
Luongo
Cristina
C
Elefante
Antonia
A
Ambrosio
Raffaele
R
Salzano
Salvatore
S
Zannini
Mariastella
M
Nitsch
Roberto
R
Di Lauro
Roberto
R
Rossi
Guido
G
Fenzi
Gianfranco
G
Salvatore
Domenico
D
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D015153:Blotting, Western; D002454:Cell Differentiation; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism / Q000502:physiology*; D002843:Chromatin; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000737:chemistry; D015536:Down-Regulation; D005786:Gene Expression Regulation; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D007438:Introns; D007477:Ions; D026901:Membrane Transport Proteins / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000502:physiology*; D009841:Oligonucleotides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000076988:Sulfate Transporters; D013961:Thyroid Gland / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000378:metabolism*; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*; D014162:Transfection
D027963:Chloride-Bicarbonate Antiporters; D002843:Chromatin; D007477:Ions; D026901:Membrane Transport Proteins; C000614412:NKX2-1 protein, human; C000614416:Nkx2-1 protein, rat; D009687:Nuclear Proteins; D009841:Oligonucleotides; D020033:Protein Isoforms; D012333:RNA, Messenger; C085609:SLC26A4 protein, human; C494615:Slc26A4 protein, rat; D000076988:Sulfate Transporters; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D004247:DNA