title: Transcriptional regulation of the sodium-coupled neutral amino acid transporter (SNAT2) by 17β-estradiol.
abstract: The sodium-coupled neutral amino acid transporter 2 (SNAT2) translocates small neutral amino acids into the mammary gland to promote cell proliferation during gestation. It is known that SNAT2 expression increases during pregnancy, and in vitro studies indicate that this transporter is induced by 17β-estradiol. In this study, we elucidated the mechanism by which 17β-estradiol regulates the transcription of SNAT2. In silico analysis revealed the presence of a potential estrogen response element (ERE) in the SNAT2 promoter. Reporter assays showed an increase in SNAT2 promoter activity when cotransfected with estrogen receptor alpha (ER-α) after 17β-estradiol stimulation. Deletion of the ERE reduced estradiol-induced promoter activity by 63%. Additionally, EMSAs and supershift assays showed that ER-α binds to the SNAT2 ERE and that this binding competes with the interaction of ER-α with its consensus ERE. An in vivo ChIP assay demonstrated that the binding of ER-α to the SNAT2 promoter gradually increased in the mammary gland during gestation and that maximal binding occurred at the highest 17β-estradiol serum concentration. Liquid chromatography-elevated energy mass spectrometry and Western blot analysis revealed that the SNAT2 ER-α-ERE complex contained poly(ADP-ribose) polymerase 1, Lupus Ku autoantigen protein p70, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) proteins and that the silencing of each of these proteins nearly abolished 17β-estradiol-stimulated SNAT2 promoter activity. Nuclear levels of GAPDH increased progressively during gestation in the mammary gland, and GAPDH binding was nucleotide-specific for the SNAT2 ERE. Thus, this study provides new insights into how the mammary epithelium adapts to control amino acid uptake through the transcriptional regulation of the SNAT2 transporter via 17β-estradiol.
authors: Posgrado en Ciencias Bioquímicas, Universidad Nacional Autónoma de México, 04510 México D.F., México;Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México;
authors: Laura A
authors: LA
authors: Velázquez-Villegas
authors: Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México;
authors: Víctor
authors: V
authors: Ortíz
authors: Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX 77204;
authors: Anders
authors: A
authors: Ström
authors: Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México;
authors: Nimbe
authors: N
authors: Torres
authors: Proteomics Programmatic Core, Houston Methodist Hospital Research Institute, Houston, TX 77030;
authors: David A
authors: DA
authors: Engler
authors: Proteomics Programmatic Core, Houston Methodist Hospital Research Institute, Houston, TX 77030;
authors: Risë
authors: R
authors: Matsunami
authors: Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México; and.
authors: David
authors: D
authors: Ordaz-Rosado
authors: Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México; and.
authors: Rocío
authors: R
authors: García-Becerra
authors: Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México;
authors: Adriana M
authors: AM
authors: López-Barradas
authors: Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México; and.
authors: Fernando
authors: F
authors: Larrea
authors: Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX 77204;Department of Biosciences and Nutrition, Karolinska Institutet, 14186 Stockholm, Sweden jgustafsson@uh.edu.
authors: Jan-Åke
authors: JÅ
authors: Gustafsson
authors: Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, 14000 México D.F., México;
authors: Armando R
authors: AR
authors: Tovar
mesh_terms: D026924:Amino Acid Transport System A; D026905:Amino Acid Transport Systems / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D034961:Antigens, Nuclear / Q000378:metabolism; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D000072200:Ku Autoantigen; D008321:Mammary Glands, Animal / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011247:Pregnancy; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D051381:Rats; D020218:Response Elements / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D026924:Amino Acid Transport System A; D026905:Amino Acid Transport Systems; D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D047628:Estrogen Receptor alpha; D010446:Peptide Fragments; C412568:Slc38a2 protein, rat; C068142:glyceraldehyde 3-phosphate dehydrogenase (304-313); D004958:Estradiol; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D011065:Poly(ADP-ribose) Polymerases; C000606509:Xrcc6 protein, human; C000606511:Xrcc6 protein, rat; D000072200:Ku Autoantigen
keywords: amino acid transport; coactivator