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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Insulin acutely triggers transcription of Slc2a4 gene: Participation of the AT-rich, E-box and NFKB-binding sites

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Moraes, Paulo Alexandre [1] ; Yonamine, Caio Yogi [1] ; Pinto Junior, Danilo Correa [1] ; DelConti Esteves, Joao Victor [1] ; Machado, Ubiratan Fabres [1] ; Mori, Rosana Cristina [1]
Total Authors: 6
[1] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Life Sciences; v. 114, n. 1, p. 36-44, SEP 26 2014.
Web of Science Citations: 10

Aims: The insulin-sensitive glucose transporter protein GLUT4 (solute carrier family 2 member 4 (Slc2a4) gene) plays a key role in glycemic homeostasis. Decreased GLUT4 expression is a current feature in insulin resistant conditions such as diabetes, and the restoration of GLUT4 content improves glycemic control. This study investigated the effect of insulin upon Slc2a4/GLUT4 expression, focusing on the AT-rich element, E-box and nuclear factor NF-kappa-B (NFKB) site. Main methods: Rat soleus muscles were incubated during 180 min with insulin, added or not with wortmannin (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit gamma isoform (PI3K)-inhibitor), ML9 (serine/threonine protein kinase (AKT) inhibitor) and tumor necrosis factor (TNF, GLUT4 repressor), and processed for analysis of GLUT4 protein (Western blotting); Slc2a4, myocyte enhancer factor 2a/d (Mef2a/d), hypoxia inducible factor 1a (Hif1a), myogenic differentiation 1 (Myod1) and nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (Nfkb1) messenger ribonucleic acids (mRNAs) (polymerase chain reaction (PCR)); and AT-rich- (myocyte-specific enhancer factor 2 (MEF2)-binding site), E-box- (hypoxia inducible factor 1 alpha (HIF1A)- and myoblast determination protein 1 (MYOD1)-binding site), and NFKB-binding activity (electrophoretic mobility assay). Key findings: Insulin increased Slc2a4 mRNA expression (140%) and nuclear proteins binding to AT-rich and E-box elements (similar to 90%), all effects were prevented by wortmannin and ML9. Insulin also increased Mef2a/d and Myod1 mRNA expression, suggesting the participation of these transcriptional factors in the Slc2a4 enhancing effect. Conversely, insulin decreased Nflkb1 mRNA expression and protein binding to the NFKB-site (similar to 50%). Furthermore, TNF-induced inhibition of GLUT4 expression (similar to 40%) was prevented by insulin in an NFKB-binding repressing mechanism. GLUT4 protein paralleled the Slc2a4 mRNA regulations. Significance: Insulin enhances the Slc2a4/GLUT4 expression in the skeletal muscle by activating AT-rich and E-box elements, in a PI3K/AKT-dependent mechanism, and repressing NFKB-site activity as well. These results unravel how post-prandial increase of insulin may guarantee GLUT4 expression, and how the insulin signaling impairment can participate in insulin resistance-induced repression of GLUT4. (C) 2014 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 12/04831-1 - New players in glycemic control and chronic complications of Diabetes mellitus: preventive and therapeutic perspectives
Grantee:Ubiratan Fabres Machado
Support type: Research Projects - Thematic Grants