Nuclear receptor-mediated regulation of lipid droplet-associated protein gene expression in adipose tissue

Author(s):  
Mark Christian

AbstractIn adipose tissues, nuclear receptors (NRs) have important metabolic actions on cellular lipid-storing capacity through targeted gene regulation. Lipid droplets (LDs) are the organelles for intracellular triacylglycerol (TAG) storage and are present in all eukaryotic cells. They are small in most cells, but in white adipocytes, they can occupy 90% of the cytoplasm. LDs consist of a TAG core surrounded by a phospholipid monolayer and an array of associated proteins that determine size, stability, inter-droplet interaction, and lipid storage capacity. The genes that encode these proteins are more highly expressed in brown compared with white fat, correlating with the greater LD surface area in multilocular brown adipocytes. Gene expression profiling reveals that most NRs are present in adipose tissues, with some showing greater expression in brown compared with white fat, including peroxisome proliferator-activated receptor (PPAR) α, estrogen-related receptor α, and NURR1. NR signaling is important for the regulated expression of most genes that encode LD-associated proteins. For example, estradiol signals via estrogen receptor α to regulate the levels of PLIN1 and the lipase ATGL controlling LD size and total lipid accumulation. PPARγ is essential for adipocyte differentiation and function, and analysis of data obtained through chromatin immunoprecipitation followed by high-throughput DNA sequencing shows that it binds to the promoters of many genes encoding LD proteins in adipocytes. Of these genes, the greatest PPARγ binding was to regulatory regions for

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1490
Author(s):  
Yanxiong Huo ◽  
Xuhong Lu ◽  
Xiaoyu Wang ◽  
Xifan Wang ◽  
Lingli Chen ◽  
...  

Probiotics are widely known for their health benefits. Mitochondrial dysfunction is related to obesity. The aim of this study was to illuminate whether Bifidobacterium animalis subsp. lactis A6 (BAA6) could improve obesity due to increased mitochondrial biogenesis and function of adipose tissues. Four-week-old male C57BL/6 mice were fed with a high-fat diet (HFD) for 17 weeks. For the final eight weeks, the HFD group was divided into three groups including HFD, HFD with BAA6 (HFD + BAA6 group), and HFD with Akkermansia muciniphila (AKK) (HFD + AKK group as positive control). The composition of the microbiota, serum lipopolysaccharides (LPS), and mitochondrial biosynthesis and function of epididymal adipose tissues were measured. Compared with the HFD group, body weight, relative fat weight, the relative abundance of Oscillibacter and Bilophila, and serum LPS were significantly decreased in the HFD + BAA6 and HFD + AKK groups (p < 0.05). Furthermore, the addition of BAA6 and AKK increased the expression of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) (by 21.53- and 18.51-fold), estrogen-related receptor α (ERRα) (by 2.83- and 1.24-fold), and uncoupling protein-1 (UCP-1) (by 1.51- and 0.60-fold) in epididymal adipose tissues. Our results suggest that BAA6 could improve obesity associated with promoting mitochondrial biogenesis and function of adipose tissues in mice.


2013 ◽  
Vol 304 (11) ◽  
pp. C1064-C1072 ◽  
Author(s):  
Angela Ramjiawan ◽  
Rushita A. Bagchi ◽  
Alexandra Blant ◽  
Laura Albak ◽  
Maria A. Cavasin ◽  
...  

The transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a key determinant of cardiac metabolic function by regulating genes governing fatty acid oxidation and mitochondrial biogenesis. PGC-1α expression is reduced in many cardiac diseases, and gene deletion of PGC-1α results in impaired cardiomyocyte metabolism and function. Reduced fuel supply generally induces PGC-1α expression, but the specific role of oxygen deprivation is unclear, and the mechanisms governing PGC-1α gene expression in these situations are poorly understood. During hypoxia of primary rat cardiomyocytes up to 12 h, we found that PGC-1α expression was downregulated via a histone deacetylation-dependent mechanism. Conversely, extended hypoxia to 24 h concomitant with glucose depletion upregulated PGC-1α expression via an AMP-activated protein kinase (AMPK)-mediated mechanism. Our previous work demonstrated that estrogen-related receptor-α (ERRα) regulates PGC-1α expression, and we show here that overexpression of ERRα was sufficient to attenuate PGC-1α downregulation in hypoxia. We confirmed that chronic hypoxia downregulated cardiac PGC-1α expression in a hypoxic but nonischemic hypobaric rat model of pulmonary hypertension. Our data demonstrate that depletion of oxygen or fuel results in repression or induction, respectively, of PGC-1α expression via discrete mechanisms, which may contribute to cardiac energetic derangement during hypoxia, ischemia, and failure.


PPAR Research ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Jérôme Eeckhoute ◽  
Frédérik Oger ◽  
Bart Staels ◽  
Philippe Lefebvre

The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) is required for differentiation and function of mature adipocytes. Its expression is induced during adipogenesis where it plays a key role in establishing the transcriptome of terminally differentiated white fat cells. Here, we review findings indicating that PPARγexpression and activity are intricately regulated through control of chromatin structure. Hierarchical and combinatorial activation of transcription factors, noncoding RNAs, and chromatin remodelers allows for temporally controlled expression of PPARγand its target genes through sequential chromatin remodelling. In obesity, these regulatory pathways may be altered and lead to modified PPARγactivity.


2006 ◽  
Vol 42 ◽  
pp. 13-29 ◽  
Author(s):  
Anna-Maria Joseph ◽  
Henriette Pilegaard ◽  
Anastassia Litvintsev ◽  
Lotte Leick ◽  
David A. Hood

Every time a bout of exercise is performed, a change in gene expression occurs within the contracting muscle. Over the course of many repeated bouts of exercise (i.e. training), the cumulative effects of these alterations lead to a change in muscle phenotype. One of the most prominent of these adaptations is an increase in mitochondrial content, which confers a greater resistance to muscle fatigue. This essay reviews current knowledge on the regulation of exercise-induced mitochondrial biogenesis at the molecular level. The major steps involved include, (i) transcriptional regulation of nuclear-encoded genes encoding mitochondrial proteins by the coactivator peroxisome-proliferator-activated receptor g coactivator-1, (ii) control of mitochondrial DNA gene expression by the transcription factor Tfam, (iii) mitochondrial fission and fusion mechanisms, and (iv) import of nuclear-derived gene products into the mitochondrion via the protein import machinery. It is now known that exercise can modify the rates of several of these steps, leading to mitochondrial biogenesis. An understanding of how exercise can produce this effect could help us decide whether exercise is beneficial for patients suffering from mitochondrial disorders, as well as a variety of metabolic diseases.


Oncogene ◽  
2021 ◽  
Vol 40 (13) ◽  
pp. 2355-2366
Author(s):  
Laura C. A. Galbraith ◽  
Ernest Mui ◽  
Colin Nixon ◽  
Ann Hedley ◽  
David Strachan ◽  
...  

AbstractPeroxisome Proliferator-Activated Receptor Gamma (PPARG) is one of the three members of the PPAR family of transcription factors. Besides its roles in adipocyte differentiation and lipid metabolism, we recently demonstrated an association between PPARG and metastasis in prostate cancer. In this study a functional effect of PPARG on AKT serine/threonine kinase 3 (AKT3), which ultimately results in a more aggressive disease phenotype was identified. AKT3 has previously been shown to regulate PPARG co-activator 1 alpha (PGC1α) localisation and function through its action on chromosome maintenance region 1 (CRM1). AKT3 promotes PGC1α localisation to the nucleus through its inhibitory effects on CRM1, a known nuclear export protein. Collectively our results demonstrate how PPARG over-expression drives an increase in AKT3 levels, which in turn has the downstream effect of increasing PGC1α localisation within the nucleus, driving mitochondrial biogenesis. Furthermore, this increase in mitochondrial mass provides higher energetic output in the form of elevated ATP levels which may fuel the progression of the tumour cell through epithelial to mesenchymal transition (EMT) and ultimately metastasis.


PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Jaou-Chen Huang

Peroxisome proliferator-activated receptorδ(PPARδ, also known as PPARβ) has ubiquitous distribution and extensive biological functions. The reproductive function of PPARδwas first revealed in the uterus at the implantation site. Since then, PPARδand its ligand have been discovered in all reproductive tissues, including the gametes and the preimplantation embryos. PPARδin preimplantation embryos is normally activated by oviduct-derived PPARδligand. PPARδactivation is associated with an increase in embryonic cell proliferation and a decrease in programmed cell death (apoptosis). On the other hand, the role of PPARδand its ligand in gamete formation and function is less well understood. This review will summarize the reproductive functions of PPARδand project its potential applications in assisted reproductive technology.


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