Long-term exposure to peroxisome proliferator-activated receptor g (PPARg) agonists such as rosiglitazone induces browning of rodent and human adipocytes; however, the transcriptional mechanisms governing this phenotypic switch in adipocytes are largely unknown. Here we show that rosiglitazone-induced browning of human adipocytes activates a comprehensive gene program that leads to increased mitochondrial oxidative capacity. Once induced, this gene program and oxidative capacity are maintained independently of rosiglitazone, suggesting that additional browning factors are activated. Browning triggers reprogramming of PPARg binding, leading to the formation of PPARg ''superenhancers'' that are selective for brown-in-white (brite) adipocytes. These are highly associated with key brite-selective genes. Based on such an association, we identified an evolutionarily conserved metabolic regulator, Kruppel-like factor 11 (KLF11), as a novel browning transcription factor in human adipocytes that is required for rosiglitazone-induced browning, including the increase in mitochondrial oxidative capacity. KLF11 is directly induced by PPARg and appears to cooperate with PPARg in a feed-forward manner to activate and maintain the brite-selective gene program.

Peroxisome proliferator-activated receptor ␥ (PPAR␥) is a master regulator of adipocyte differentiation and function. We and others have previously mapped PPAR␥ binding at a genome-wide level in murine and human adipocyte cell lines and in primary human adipocytes. However, little is known about how binding patterns of PPAR␥ differ between brown and white adipocytes and among different types of white adipocytes. Here we have employed chromatin immunoprecipitation combined with deep sequencing to map and compare PPAR␥ binding in in vitro differentiated primary mouse adipocytes isolated from epididymal, inguinal, and brown adipose tissues. While these PPAR␥ binding profiles are overall similar, there are clear depot-selective binding sites. Most PPAR␥ binding sites previously mapped in 3T3-L1 adipocytes can also be detected in primary adipocytes, but there are a large number of PPAR␥ binding sites that are specific to the primary cells, and these tend to be located in closed chromatin regions in 3T3-L1 adipocytes. The depot-selective binding of PPAR␥ is associated with highly depot-specific gene expression. This indicates that PPAR␥ plays a role in the induction of genes characteristic of different adipocyte lineages and that preadipocytes from different depots are differentially preprogrammed to permit PPAR␥ lineage-specific recruitment even when differentiated in vitro.M ammals have fat depots at various locations in the body. Classically, these tissues have been characterized as either white adipose tissue (WAT) or brown adipose tissue (BAT). Both tissues store energy in the form of triglycerides; however, whereas WAT releases the energy as fatty acids that can be converted to metabolic energy in other tissues, BAT metabolizes the fatty acids in the adipocytes and releases the energy as heat. This unique energy-dispersing function of BAT relies on the high number of mitochondria in the adipocytes and the expression and activation of uncoupling protein 1 (UCP1), residing in the inner mitochondrial membrane (9). Previously, BAT was thought to be present only in newborn and hibernating mammals; however, recently it was demonstrated that also human adults have discrete BAT depots (13,38,46,58,61). It has been suggested that activation of these BAT depots could increase energy expenditure and lead to weight loss. Consistent with this, there seems to be a negative correlation between body mass index and the presence of BAT (13,68,69) Notably, it has also been indicated that different WAT depots are not identical but have different properties (57,62). It is currently unclear to what extent differences between the distinct WAT depots reflect differences at the cellular level between adipocytes in the depots or reflect context-dependent differences (e.g., microenvironment); however, recent evidence indicates that different subtypes of white adipocytes do exist. Thus, several studies have demonstrated different gene expression profiles between visceral and subcutaneous WAT and preadipocytes and adipocytes from these tiss...

Background As pathogenic variants in the gene for RBM20 appear with a frequency of 6% among Danish patients with dilated cardiomyopathy (DCM), it was the aim to investigate the associated disease expression in affected families. Methods and Results Clinical investigations were routinely performed in DCM index-patients and their relatives. In addition, ≥76 recognized and likely DCM-genes were investigated. DNA-sequence-variants within RBM20 were considered suitable for genetic testing when they fulfilled the criteria of (1) being pathogenic according to the American College of Medical Genetics and Genomics-classification, (2) appeared with an allele frequency of <1:10.000, and (3) segregated with DCM in ≥7 affected individuals. A total of 80 individuals from 15 families carried 5 different pathogenic RBM20 -variants considered suitable for genetic testing. The penetrance was 66% (53/80) and age-dependent. Males were both significantly younger and had lower ejection fraction at diagnosis than females (age, 29±11 versus 48±12 years; P <0.01; ejection fraction, 29±13% versus 38±9%; P <0.01). Furthermore, 11 of 31 affected males needed a cardiac transplant while none of 22 affected females required this treatment ( P <0.001). Thirty percent of RBM20 -carriers with DCM died suddenly or experienced severe ventricular arrhythmias although no adverse events were identified among healthy RBM20 -carriers with a normal cardiac investigation. The event-free survival of male RBM20 -carriers was significantly shorter compared with female carriers ( P <0.001). Conclusions The disease expression associated with pathogenic RBM20 -variants was severe especially in males. The findings of the current study suggested that close clinical follow-up of RBM20 -carriers is important which may ensure early detection of disease development and thereby improve management.

Nuclear receptors (NRs) are key transcriptional regulators of metazoan physiology and metabolism. Different NRs bind to similar or even identical core response elements; however, they regulate transcription in a highly receptor- and gene-specific manner. These differences in gene activation can most likely be accounted for by mechanisms involving receptor-specific interactions with DNA as well as receptor-specific interactions with protein complexes binding to adjacent and distant DNA sequences. Here, we review key molecular aspects of transactivation by NRs with special emphasis on the recent advances in the molecular mechanisms responsible for receptor- and gene-specific transcriptional activation. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.

We have previously shown that adenoviral expression of peroxisome proliferator-activated receptors (PPARs) leads to rapid establishment of transcriptionally active complexes and activation of target gene expression within 5-8 h after transduction. Here we have used the adenoviral delivery system combined with expression array analysis to identify novel putative PPARgamma target genes in murine fibroblasts and to determine the role of the A/B-domain in PPARgamma-mediated transactivation of genomic target genes. Of the 257 genes found to be induced by PPARgamma2 expression, only 25 displayed A/B-domain dependency, i.e. significantly reduced induction in the cells expressing the truncated PPARgamma lacking the A/B-domain (PPARgammaCDE). Nine of the 25 A/B-domain-dependent genes were involved in lipid storage, and in line with this, triglyceride accumulation was considerably decreased in the cells expressing PPARgammaCDE compared with cells expressing full-length PPARgamma2. Using chromatin immunoprecipitation, we demonstrate that PPARgamma binding to genomic target sites and recruitment of the mediator component TRAP220/MED1/PBP/DRIP205 is not affected by the deletion of the A/B-domain. By contrast, the PPARgamma-mediated cAMP response element-binding protein (CREB)-binding protein (CBP) and p300 recruitment to A/B-domain-dependent target genes is compromised by deletion of the A/B-domain. These results indicate that the A/B-domain of PPARgamma2 is specifically involved in the recruitment or stabilization of CBP- and p300-containing cofactor complexes to a subset of target genes.