International Journal of Medical Sciences

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17 August 2018

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Int J Med Sci 2018; 15(12):1320-1328. doi:10.7150/ijms.26774

Short Research Communication

Estrogen Receptor 1 (ESR1) Enhances Slc2a4/GLUT4 Expression by a SP1 Cooperative Mechanism

João Nilton Barreto-Andrade, Luciana Alves de Fátima, Raquel Saldanha Campello, José Augusto Cipriano Guedes, Helayne Soares de Freitas, Maristela Mitiko Okamoto Ubiratan Fabres Machado

Departament of Physiology and Biophysics, Institute of Biomedical Sciences, Universidade de São Paulo, São Paulo, Brasil.

Abstract

Background: Estrogens are involved in glycemic regulation, playing an important role in the development and/or progression of insulin resistance. For that, estrogens regulate the expression of the glucose transporter protein GLUT4 (codified by the solute carrier family 2 member 4 gene, Slc2a4), thus modulating adipose and muscle glucose disposal. This regulation is a balance between ESR1-mediated enhancer effect and ESR2-mediated repressor effect on Slc2a4 gene. However, molecular mechanisms involved in these effects are poorly understood. Since the specificity protein 1 (SP1) participates in several ESR-mediated genomic regulations, the aim of the present study is to investigate the participation of SP1 in the ESR1/2-mediated regulation of Slc2a4 gene.

Methods: Differentiated 3T3-L1 adipocytes were 24-hour challenged with 10 nM estradiol (E2) and 10 nM ESR1 agonist (PPT) or 100 nM ESR2 agonist (DPN), added or not with E2. Slc2a4 and Sp1 mRNAs (RT-qPCR), total GLUT4 and nuclear ESR1, ESR2 and SP1 proteins (Western blotting), SP1 binding activity into Slc2a4 promoter (EMSA), and nuclear complexation of SP1/ESR1 (immunoprecipitation) were analyzed.

Results: E2 and PPT increased (25-50%) whereas DPN reduced (20-45%) Slc2a4 and GLUT4 expression. Nuclear content of ESR1 and ESR2 remained unchanged. Nuclear content of SP1 increased (50 to 90%) by PPT and DPN added or not with E2; the highest effect observed with PPT alone. PPT also increased the nuclear content of SP1/ESR1 complex and the SP1 binding into the Slc2a4 promoter.

Conclusions: ESR1 activation in adipocytes increased the nuclear content of SP1 protein, the SP1/ESR1 interaction and SP1 binding into the Slc2a4 gene promoter, culminating with increased Slc2a4/GLUT4 expression. No involvement of SP1 seems to occur in ESR2-mediated repressor effect on Slc2a4. We expect that this ESR1/SP1 cooperative effect can contribute to the development of new approaches for prevention or treatment of insulin resistance and diabetes mellitus.

Keywords: Estradiol, PPT, DPN, ESR2, 3T3-L1 adipocytes

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How to cite this article:
Barreto-Andrade JN, de Fátima LA, Campello RS, Guedes JAC, de Freitas HS, Machado MMOUF. Estrogen Receptor 1 (ESR1) Enhances Slc2a4/GLUT4 Expression by a SP1 Cooperative Mechanism. Int J Med Sci 2018; 15(12):1320-1328. doi:10.7150/ijms.26774. Available from http://www.medsci.org/v15p1320.htm