Regulation of human resistin gene expression in cell systems: an important role of stimulatory protein 1 interaction with a common promoter polymorphic site

Abstract

Aims/hypothesis: Resistin is an adipokine that might link obesity and insulin resistance. A common polymorphism of the human resistin gene, −420C>G, is a major determinant of plasma resistin concentrations as well as resistin mRNA expression in human adipose tissue. In this study, we investigated the regulatory mechanism by which this polymorphism affects resistin expression. Methods: Electrophoretic mobility shift assay was performed to identify the transcription factors binding to the −420G region. Transient transfection and reporter assay were used to measure promoter activities of the resistin gene. The binding ability of stimulatory protein 1 (Sp1) in response to adipocyte differentiation or high glucose concentrations was also measured. Results: Sp1 and stimulatory protein 3 (Sp3) specifically bound to the region around −420G of the human resistin gene. Overexpression of Sp1 increased the promoter activity regardless of −420 genotypes, while the promoter activity of the −420G construct was two-fold higher than that of the −420C construct. In contrast, overexpression of Sp3 scarcely increased the promoter activity. The binding ability of Sp1 to the −420G region was increased in response to adipocyte differentiation. Mithramycin A, an inhibitor of DNA binding of Sp1, reduced the effect of high glucose on transcription induction of the resistin gene in adipocytes. Conclusions/interpretation: These results suggest that Sp1 is an important factor regulating transcription of human resistin gene. A common polymorphism of the human resistin promoter, −420C>G, is critical for the binding of Sp1 and modulates the transcriptional activity of the resistin gene by changing the binding ability of Sp1. In addition, Sp1 may be involved in the increase of resistin expression by hyperglycaemia.

Transcriptional Regulation of the Hypoxia Inducible Factor-2.ALPHA. (HIF-2.ALPHA.) Gene during Adipose Differentiation in 3T3-L1 Cells

“…This pattern is quite similar to the previous report showing the binding of Sp1 and Sp3 in 3T3-L1 cells to the target sequence. 16,17) Also, the antibodies for Sp1 and Sp3 immunoprecipitated the DNA containing the sequence -478/-445 (Fig. 4A).…”

A Pilot Study Suggests that the G/G Genotype of Resistin Single Nucleotide Polymorphism at -420 May Be an Independent Predictor of a Reduction in Fasting Plasma Glucose and Insulin Resistance by Pioglitazone in Type 2 Diabetes

“…expression of the mouse resistin gene by modulating Sp1 activity via o-glycosylation in 3t3-L1 adipocytes [35]. Sp1 binding sites of the mouse resistin gene promoter were required for mediating this repression.…”

Resistin 420C/G gene polymorphism on circulating resistin, metabolic risk factors and insulin resistance in adult women

“…We observed a direct correlation of BMI, waist hip ratio and waist circumference with resistin level in this study as also shown by some other studies that association of 420C/G polymorphism and the presence of metabolic syndrome were noticed in overweight/obese women [35], however adiposity (predictable by BMI) does not consistently correlate with resistin level in some of the studies [36]. The DNA element of SNP-420C and SNP-420G of resistin gene had different binding affinities for stimulatory protein 1 (Sp1) and stimulatory protein 3 (Sp3), Sp1 and Sp3 transcription factors specifically bound to the DNA element of SNP-420G with high affinity and enhanced expression of the resistin gene [37]. SNP-420C/G at the resistin locus captures only a small part of the total genetic contribution to circulating resistin variation.…”