CCAAT/enhancer-binding proteins are key regulators of human type two deiodinase expression in a placenta cell line.
An appropriate concentration of intracellular T(3) is a critical determinant of placenta development and function and is mainly controlled by the activity of type II deiodinase (D2). The levels of this enzyme are finely regulated in different tissues by coordinated transcriptional mechanisms, which rely on dedicated promoter sequences (e.g. cAMP response element and TATA elements) that impart inducibility and tissue specificity to Dio2 mRNA expression. Here we show that CCAAT enhancer-binding proteins α and β (C/EBPα and C/EBPβ) promote Dio2 expression in the trophoblastic cell line JEG3 through a conserved CCAAT element, which is a novel key component of the Dio2 promoter code that confers tissue-specific expression of D2 in these cells. Increased C/EBPs levels potently induce Dio2 transcription, whereas their ablation results in loss of Dio2 mRNA. By measuring the activity of several deletion and point mutant promoter constructs, we have identified the functional CCAAT element responsible for this effect, which is located in close proximity to the most 5' TATA box. Notably, this newly identified sequence is highly conserved throughout the species and binds in vivo and in vitro C/EBP, indicating the relevance of this regulatory mechanism. Together, our results unveil a novel mechanism of regulation of D2 expression in a trophoblastic cell line, which may play a relevant role during placenta development.
Laboratory of Molecular Oncology Department of Molecular Medicine, “Sapienza” University of Rome, I-00161 Rome and I-04100 Latina, Italy. gianluca.canettieri@uniroma1.it
Gianluca
G
Canettieri
Maria Giulia
MG
Santaguida
Laura
L
Antonucci
Michele
M
Della Guardia
Antonella
A
Franchi
Sonia
S
Coni
Alberto
A
Gulino
Marco
M
Centanni
D015153:Blotting, Western; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097564:Iodothyronine Deiodinase Type II
D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D007453:Iodide Peroxidase; D000097564:Iodothyronine Deiodinase Type II