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Transcriptional regulation of the sodium‐coupled neutral amino acid transporter (SNAT2) by 17β‐estradiol
Author(s) -
VelazquezVillegas Laura,
Ortiz Victor,
OrdazRosado David,
GarciaBecerra Rocio,
Larrea Fernando,
Torres Nimbe,
Tovar Armando R
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.550.12
Subject(s) - luciferase , hormone response element , microbiology and biotechnology , biology , reporter gene , promoter , transcription factor , estrogen , transfection , estrogen receptor , chemistry , gene expression , gene , biochemistry , endocrinology , genetics , cancer , breast cancer
The SNAT2 amino acid transporter allows the entry of small neutral amino acids into the mammary gland to promote cell proliferation during gestation and milk protein synthesis during lactation. During pregnancy, 17β‐estradiol promotes the expression of this transporter by increasing SNAT2 promoter activity. The objective of this work was to elucidate the mechanism by which the 17β‐estradiol regulates the transcription of SNAT2. Computational analysis of the promoter region of SNAT2 showed the presence of a potential estrogen response element (ERE). Studies in HeLa cells using the luciferase reporter gene showed that the activity of the promoter region of SNAT2 increased with the co‐transfection of constructions with progressive deletions of SNAT2 promoter, and the plasmid that expresses the estrogen receptor alpha (ERα). The highest luciferase activity was found with the construct containing the ERE (40%), but 20% of activity remained in smaller constructions. EMSA and supershift assays showed that ERα binds to the ERE in SNAT2 promoter and this binding competed with ERα interaction to its consensus sequence. This binding was also demonstrated in vivo by ChIP assay where ERα bound to the promoter region of SNAT2 in the mammary gland of pregnant rats on days 5, 14 and 20 of gestation. We conclude that 17β‐estradiol increased SNAT2 promoter activity in the presence of ERα by a classic genomic pathway.