Sterol regulatory element binding protein 1 interacts with pregnane X receptor and constitutive androstane receptor and represses their target genes

2008 ◽  
Vol 18 (4) ◽  
pp. 325-337 ◽  
Author(s):  
Adrian Roth ◽  
Renate Looser ◽  
Michel Kaufmann ◽  
Urs A. Meyer
2013 ◽  
Vol 6 (2) ◽  
pp. 107-122 ◽  
Author(s):  
Frédéric Capel ◽  
Gaëlle Rolland-Valognes ◽  
Catherine Dacquet ◽  
Manuel Brun ◽  
Michel Lonchampt ◽  
...  

2004 ◽  
Vol 287 (6) ◽  
pp. E1039-E1048 ◽  
Author(s):  
Caroline Améen ◽  
Daniel Lindén ◽  
Britt-Mari Larsson ◽  
Agneta Mode ◽  
Agneta Holmäng ◽  
...  

We investigated whether the sexually dimorphic secretory pattern of growth hormone (GH) in the rat regulates hepatic gene expression of sterol regulatory element-binding protein-1c (SREBP-1c) and its target genes. SREBP-1c, fatty acid synthase (FAS), and glycerol-3-phosphate acyltransferase (GPAT) mRNA were more abundant in female than in male livers, whereas acetyl-CoA carboxylase-1 (ACC1) and stearoyl-CoA desaturase-1 (SCD-1) were similarly expressed in both sexes. Hypophysectomized female rats were given GH as a continuous infusion or as two daily injections for 7 days to mimic the female- and male-specific GH secretory patterns, respectively. The female pattern of GH administration increased the expression of SREBP-1c, ACC1, FAS, SCD-1, and GPAT mRNA, whereas the male pattern of GH administration increased only SCD-1 mRNA. FAS and SCD-1 protein levels were regulated in a similar manner by GH. Incubation of primary rat hepatocytes with GH increased SCD-1 mRNA levels and decreased FAS and GPAT mRNA levels but had no effect on SREBP-1c mRNA. GH decreased hepatic liver X receptor-α (LXRα) mRNA levels both in vivo and in vitro. Feminization of the GH plasma pattern in male rats by administration of GH as a continuous infusion decreased insulin sensitivity and increased expression of FAS and GPAT mRNA but had no effect on SREBP-1c, ACC1, SCD-1, or LXRα mRNA. In conclusion, FAS and GPAT are specifically upregulated by the female secretory pattern of GH. This regulation is not a direct effect of GH on hepatocytes and does not involve changed expression of SREBP-1c or LXRα mRNA but is associated with decreased insulin sensitivity.


2006 ◽  
Vol 281 (21) ◽  
pp. 15013-15020 ◽  
Author(s):  
Jie Zhou ◽  
Yonggong Zhai ◽  
Ying Mu ◽  
Haibiao Gong ◽  
Hirdesh Uppal ◽  
...  

2009 ◽  
Vol 30 (5) ◽  
pp. 1182-1198 ◽  
Author(s):  
Virginie Lecomte ◽  
Emmanuelle Meugnier ◽  
Vanessa Euthine ◽  
Christine Durand ◽  
Damien Freyssenet ◽  
...  

ABSTRACT The role of the transcription factors sterol regulatory element binding protein 1a (SREBP-1a) and SREBP-1c in the regulation of cholesterol and fatty acid metabolism has been well studied; however, little is known about their specific function in muscle. In the present study, analysis of recent microarray data from muscle cells overexpressing SREBP1 suggested that they may play a role in the regulation of myogenesis. We then demonstrated that SREBP-1a and -1c inhibit myoblast-to-myotube differentiation and also induce in vivo and in vitro muscle atrophy. Furthermore, we have identified the transcriptional repressors BHLHB2 and BHLHB3 as mediators of these effects of SREBP-1a and -1c in muscle. Both repressors are SREBP-1 target genes, and they affect the expression of numerous genes involved in the myogenic program. Our findings identify a new role for SREBP-1 transcription factors in muscle, thus linking the control of muscle mass to metabolic pathways.


2015 ◽  
Vol 35 (2) ◽  
pp. 803-815 ◽  
Author(s):  
Andreas Bitter ◽  
Andreas K. Nüssler ◽  
Wolfgang E. Thasler ◽  
Kathrin Klein ◽  
Ulrich M. Zanger ◽  
...  

Background/Aims: Sterol regulatory element-binding protein (SREBP) 1, the master regulator of lipogenesis, was shown to be associated with non-alcoholic fatty liver disease, which is attributed to its major isoform SREBP1c. Based on studies in mice, the minor isoform SREBP1a is regarded as negligible for hepatic lipogenesis. This study aims to elucidate the expression and functional role of SREBP1a in human liver. Methods: mRNA expression of both isoforms was quantified in cohorts of human livers and primary human hepatocytes. Hepatocytes were treated with PF-429242 to inhibit the proteolytic activation of SREBP precursor protein. SREBP1a-specifc and pan-SREBP1 knock-down were performed by transfection of respective siRNAs. Lipogenic SREBP-target gene expression was analyzed by real-time RT-PCR. Results: In human liver, SREBP1a accounts for up to half of the total SREBP1 pool. Treatment with PF-429242 indicated SREBP-dependent auto-regulation of SREBP1a, which however was much weaker than of SREBP1c. SREBP1a-specifc knock-down also reduced significantly the expression of SREBP1c and of SREBP-target genes. Regarding most SREBP-target genes, simultaneous knock-down of both isoforms resulted in effects of only similar extent as SREBP1a-specific knock-down. Conclusion: We here showed that SREBP1a is significantly contributing to the human hepatic SREBP1 pool and has a share in human hepatic lipogenic gene expression.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Changjin Liu ◽  
Ying Li ◽  
Guowei Zuo ◽  
Wenchun Xu ◽  
Huanqing Gao ◽  
...  

Oleanolic acid (OA), contained in more than 1620 plants and as an aglycone precursor for naturally occurred and synthesized triterpenoid saponins, is used in China for liver disorders in humans. However, the underlying liver-protecting mechanisms remain largely unknown. Here, we found that treatment of rats with OA (25 mg/kg/day, gavage, once daily) over 10 weeks diminished liquid fructose-induced excess hepatic triglyceride accumulation without effect on total energy intake. Attenuation of the increased vacuolization and Oil Red O staining area was evident on histological examination of liver in OA-treated rats. Hepatic gene expression profile demonstrated that OA suppressed fructose-stimulated overexpression of sterol regulatory element-binding protein-(SREBP-) 1/1c mRNA and nuclear protein. In accord, overexpression of SREBP-1c-responsive genes responsible for fatty acid synthesis was also downregulated. In contrast, overexpressed nuclear protein of carbohydrate response element-binding protein and its target genes liver pyruvate kinase and microsomal triglyceride transfer protein were not altered. Additionally, OA did not affect expression of peroxisome proliferator-activated receptor-gamma- and -alpha and their target genes. It is concluded that modulation of hepatic SREBP-1c-mediated expression of the genes responsible for de novo fatty acid synthesis plays a pivotal role in OA-elicited diminishment of fructose-induced fatty liver in rats.


2006 ◽  
Vol 20 (10) ◽  
pp. 2265-2277 ◽  
Author(s):  
Hannelore V. Heemers ◽  
Guido Verhoeven ◽  
Johannes V. Swinnen

Abstract The cellular effects of androgens are mediated by a cognate receptor, the androgen receptor. Typically, the androgen receptor is viewed to exert its activity by binding to androgen response elements located in or near the promoter region of target genes, thereby directly affecting the expression of these genes. However, increasing evidence indicates that androgens may also indirectly influence the expression of genes that do not contain androgen response elements by modulating the activity of secondary transcription factors, mediating the expression of growth factors acting in a paracrine or autocrine fashion, or by inducing changes in the production of other hormones. These indirect effects of androgens can induce cascade-like actions and may play an important role in more complex processes involving coordinated responses of genes, cells, and organs. Previously, our laboratory has identified and characterized a novel indirect mechanism of androgen action involving proteolytical activation of the key lipogenic transcription factor sterol regulatory element-binding protein (SREBP), resulting in the coordinate up-regulation of entire cellular lipogenic pathways. Interestingly, activation of SREBPs by androgens occurs not only under normal physiological conditions but has also been observed in a growing number of pathologies, and more in particular in the setting of steroid-regulated cancers, where increased lipogenesis has been shown to have remarkable diagnostic and prognostic potential and is considered a prime target for novel therapeutic approaches. This review aims to analyze current insights into the molecular mechanism(s) underlying androgen activation of the SREBP pathway and to ascertain the extent to which this phenomenon can be generalized to androgen-responsive cell systems.


1995 ◽  
Vol 270 (49) ◽  
pp. 29422-29427 ◽  
Author(s):  
Xianxin Hua ◽  
Juro Sakai ◽  
Ho Y. K. ◽  
Joseph L. Goldstein ◽  
Michael S. Brown

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