A GC-rich Region Containing Sp1 and Sp1-like Binding Sites Is a Crucial Regulatory Motif for Fatty Acid Synthase Gene Promoter Activity in Adipocytes

Abstract

We have previously shown that the proximal 2-kb sequence of the fatty acid synthase (FAS) promoter transfected into rat adipocytes was highly sensitive to the cellular context, displaying an overactivity in obese (fa/fa) versus lean Zucker rat adipocytes. Using deletional analysis, we show here that FAS promoter activity mainly depends on a region from -200 to -126. This sequence exerts a strong negative effect on FAS promoter in adipocytes from lean rats but not in those from obese rats, resulting in a marked overtranscriptional activity in the latter cells. This region, fused to a heterologous promoter, the E1b TATA box, induced differential levels of gene reporter activity in lean and obese rat adipocytes, indicating it harbors fa-responsive element(s). Whatever the rat genotype, adipocyte nuclear proteins were shown to footprint the same protected sequence within the fa-responsive region, and supershift analysis demonstrated that Sp1 or Sp1-like proteins were bound to this DNA subregion. Compelling evidence that the Sp1 binding site contained in this sequence was implicated in the differential promoter activity in lean versus obese rats, was provided by the observation that mutations at this Sp1 site induced a 2.5-fold increase in FAS promoter activity in adipocytes from lean rats, whereas they had no effect in adipocytes from obese rats.

The Regulation of Fatty Acid Synthase by STAT5A

“…Our results show that PRL did not affect the protein turnover of FAS but indicate that changes in FAS levels are mediated at the transcriptional level. Our experiments are supported by other studies (25,28,(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48) that demonstrate that FAS can be modulated at the transcriptional level. However, increased turnover of FAS mRNA in 3T3-F442A adipocytes has been demonstrated as one of the means through which GH attenuates the induction of FAS by insulin (10).…”

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

“…Although Sp1 and Sp3 share similar DNA binding domains and bind to DNA with a similar affinity, these factors differentially regulate transcription. 20,21) In general, Sp1 activates transcription of a large number of genes, while Sp3 comprises an additional inhibitory domain, leading to either activation or repression depending on the promoter and cellular context. [13][14][15] The present study showed that co-transfection of Sp1 with Sp3 diminished the Sp3-mediated transcriptional repression (Fig.…”

Transcriptional Regulatory Region for Expression of the Rat ATP Citrate‐Lyase Gene

“…Daniel and Kim [26] reported that promoter I1 of the acetyl-CoA carboxylase gene (-340 to -249) was activated by high concentrations of glucose and the effect of glucose was mediated by Spl, which can bind to the glucose response elements in promoter 11. However, Rolland et al [27] reported that FAS promoter activity mainly depended on a region from -200 to -126 and this sequence exerted a strong negative effect on FAS promoter in adipocytes from lean rats but not in those from obese rats. They demonstrated that Spl or Spl-like proteins were bound to this DNA subregion.…”