An Additive Effect of Promoting Thermogenic Gene Expression in Mice Adipose-Derived Stromal Vascular Cells by Combination of Rosiglitazone and CL316,243

Spermidine activates adipose tissue thermogenesis through autophagy and fibroblast growth factor 21

Spermidine exerts protective roles in obesity, while the mechanism of spermidine in adipose tissue thermogenesis remains unclear. The present study first investigated the effect of spermidine on cold-stimulation and β3-adrenoceptor agonist-induced thermogenesis in lean and high-fat diet-induced obese mice. Next, the role of spermidine on glucose and lipid metabolism in different types of adipose tissue was determined. Here, we found that spermidine supplementation did not affect cold-stimulated thermogenesis in lean mice, while significantly promoting the activation of adipose tissue thermogenesis under cold stimulation and β3-adrenergic receptor agonist treatment in obese mice. Spermidine treatment markedly enhanced glucose and lipid metabolism in adipose tissues, and these results were associated with the activated autophagy pathway. Moreover, spermidine up-regulated fibroblast growth factor 21 (FGF21) signaling and its downstream pathway, including PI3K/AKT and AMPK pathways in vivo and in vitro. Knockdown of Fgf21 or inhibition of PI3K/AKT and AMPK pathways in brown adipocytes abolished the thermogenesis-promoting effect of spermidine, suggesting that the effect of spermidine on adipose tissue thermogenesis might be regulated by FGF21 signaling via the PI3K/AKT and AMPK pathways. The present study provides new insight into the mechanism of spermidine on obesity and its metabolic complications, thereby laying a theoretical basis for the clinical application of spermidine.

Browning of Mesenteric White Adipose Tissue in Crohn's Disease: A New Pathological Change and Therapeutic Target

BACKROUND

Hypertrophic mesenteric adipose tissue [htMAT] is a distinctive hallmark of Crohn's disease [CD], and it affects enteritis via inflammatory adipokine secretion by dysfunctional white adipocytes. White adipocytes can become beige adipocytes, which are characterized by active lipid consumption and favourable endocrine function, via white adipocyte browning. Our study aimed to determine whether white adipocyte browning occurs in htMAT and its role in CD.

METHODS

White adipocyte browning was examined in MAT samples from CD patients and controls. Human MAT explants and primary mesenteric adipocytes were cultured for in vitro experiments. Mice with 2,4,6-trinitrobenzenesulphonic acid solution [TNBS]-induced colitis were used for in vivo studies. A β3-adrenergic receptor agonist [CL316,243] was used to induce white adipocyte browning, and IL-4/STAT6 signalling was analysed to explore the mechanism underlying the anti-inflammatory activity of beige adipocytes.

RESULTS

White adipocyte browning was observed in htMAT from CD patients, as shown by the appearance of uncoupling protein 1 [UCP1]-positive multilocular [beige] adipocytes with lipid-depleting activity and anti-inflammatory endocrine profiles. Both human MAT and primary mesenteric adipocytes from CD patients and controls could be induced to undergo browning, which increased their lipid-depleting and anti-inflammatory activities in vitro. Inducing MAT browning ameliorated mesenteric hypertrophy and inflammation as well as colitis in TNBS-treated mice in vivo. The anti-inflammatory activity of beige adipocytes was at least partially related to STAT6 signalling activation via the autocrine and paracrine effects of IL-4.

CONCLUSION

White adipocyte browning is a newly identified pathological change in htMAT of CD patients and a possible therapeutic target.

Synergistic Treatment of Obesity via Locally Promoting Beige Adipogenesis and Antioxidative Defense in Adipose Tissues

Obesity is a primary risk factor for type 2 diabetes, cardiovascular diseases, cancer, and other chronic diseases. Current antiobesity medications need frequent administration and show limited efficacy with severe side effects. Herein, browning agent rosiglitazone (Rsg) and antioxidant manganese tetroxide nanoparticles (MnNPs, around 250 nm) are integrated into electrospun short fibers (SF@Rsg-Mn) with a 1.5 μm width and a 20 μm length. Upon injection into inguinal adipose tissues, SF@Rsg-Mn are well retained in the local depots to sustainably release Rsg in 30 days for adipose tissue browning, while MnNPs on the fiber surface continuously scavenge adipose reactive oxygen species (ROS) for an extended period of time. Synergistic inhibition of fat accumulation through ROS scavenging and white adipocyte browning has been demonstrated for the first time, and the optimal synergistic ratio of Rsg and MnNPs is determined to be 1/14 via combination index examination. SF@Rsg-Mn inhibit lipid accumulation through downregulation of adipogenic gene PPARγ while promoting energy expenditure through upregulation of brown-specific gene UCP1 and mitochondrial function gene COX7A1. In a diet-induced obesity mouse model, a single injection of SF@Rsg-Mn into inguinal adipose tissues has accomplished a synergistic effect on body weight loss, fat reduction, glucose, and lipid metabolic improvement while minimizing adverse effects on other tissues, thereby paving the way to efficacious, safe, and practical treatment of obesity.

Adipose-Derived Stromal Cells Attenuate Adipose Inflammation in Obesity through Adipocyte Browning and Polarization of M2 Macrophages

Obesity is a metabolic condition associated with multiple health problems such as endocrine and metabolic dysfunction and chronic inflammation in adipose tissues. In this study, the ADSCs could be stimulated to differentiate into brown adipocyte with rosiglitazone treatment based on the Oil-Red-O staining trial. Furthermore, the multilocular lipid droplets located in the center was increased in differentiated brown adipocytes, and brown fat-associated proteins, UCP1, PPAR-γ, and LPL were highly expressed in brown adipocytes differentiated from ADSCs. Additionally, the results of animal experiments showed that both weight and amount of VLDL and LDL were decreased in the serum of obese mice after transplantation of rosiglitazone-induced brown adipocytes, while the level of HDL increased. Moreover, the proteins associated with lipid metabolism, LPA and UCP1, were downregulated, and the inflammatory response was suppressed through inhibition of the ITGAM/NF-κB-mediated proinflammatory responses and polarization of M2 macrophages. Similarly, the amounts of proinflammatory cytokines, TNF-α, IL-6, and IL-1β were decreased after rosiglitazone-induced brown adipocyte transplantation. On the contrary, anti-inflammatory cytokine IL-10 was significantly increased in both groups of obese mice, with or without brown adipocyte transplantation. Therefore, the adipose-derived stromal cells with induced browning could promote lipid consumption and alternative polarization of M2 macrophages to attenuate adipose inflammation in obesity mouse models, which thus provides a potential therapy for obesity.

Rosiglitazone Enhances Browning Adipocytes in Association with MAPK and PI3-K Pathways During the Differentiation of Telomerase-Transformed Mesenchymal Stromal Cells into Adipocytes

Obesity is a major risk for diabetes. Brown adipose tissue (BAT) mediates production of heat while white adipose tissue (WAT) function in the storage of fat. Roles of BAT in the treatment of obesity and related disorders warrants more investigation. Peroxisome proliferator activator receptor gamma (PPAR-γ) is the master regulator of both BAT and WAT adipogenesis and has roles in glucose and fatty acid metabolism. Adipose tissue is the major expression site for PPAR-γ. In this study, the effects of rosiglitazone on the brown adipogenesis and the association of MAPK and PI3K pathways was investigated during the in vitro adipogenic differentiation of telomerase transformed mesenchymal stromal cells (iMSCs). Our data indicate that 2 µM rosiglitazone enhanced adipogenesis by over-expression of PPAR-γ and C/EBP-α. More specifically, brown adipogenesis was enhanced by the upregulation of EBF2 and UCP-1 and evidenced by multilocular fatty droplets morphology of the differentiated adipocytes. We also found that rosiglitazone significantly activated MAPK and PI3K pathways at the maturation stage of differentiation. Overall, the results indicate that rosiglitazone induced overexpression of PPAR-γ that in turn enhanced adipogenesis, particularly browning adipogenesis. This study reports the browning effects of rosiglitazone during the differentiation of iMSCs into adipocytes in association with the activation of MAPK and PI3K signaling pathways.

Beta 3 Adrenergic Receptor Activation Rescues Metabolic Dysfunction in Female Estrogen Receptor Alpha-Null Mice

Metabolic disease risk escalates following menopause. The mechanism is not fully known, but likely involves reduced signaling through estrogen receptor alpha (ERα), which is highly expressed in brown and white adipose tissue (BAT and WAT).

Objective: Test the hypothesis that uncoupling protein (UCP1) activation mitigates metabolic dysfunction caused by loss of signaling through ERα.

Methods: At 8 weeks of age, female ERα knock out (KO) and wild-type mice were housed at 28°C and fed a Western-style high-fat, high sucrose diet (HFD) or a normal low-fat chow diet (NC) for 10 weeks. During the final 2 weeks, they received daily injections of CL 316,256 (CL), a selective β3 adrenergic agonist, or vehicle control (CTRL), creating eight groups: WT-CTRL, WT-CL, KO-CTRL, and KO-CL on HFD or NC; n = 4–10/group.

Results: ERαKO demonstrated exacerbated HFD-induced adiposity gain (P < 0.001) and insulin resistance (P = 0.006). CL treatment improved insulin sensitivity (P < 0.05) and normalized ERαKO-induced adiposity increase (P < 0.05). In both genotypes, CL increased resting energy expenditure (P < 0.05) and induced WAT beiging indicated by increased UCP1 protein in both perigonadal (PGAT) and subcutaneous (SQAT) depots. These effects were attenuated under HFD conditions (P < 0.05). In KO, CL reduced HFD energy consumption compared to CTRL (P < 0.05). Remarkably, CL increased WAT ERβ protein levels of both WT and KO (P < 0.001), revealing CL-mediated changes in estrogen signaling may have protective metabolic effects.

Conclusion: CL completely restored metabolic dysfunction in ERαKO mice. Thus, UCP1 may be a therapeutic target for treating metabolic dysfunction following loss of estrogen receptor signaling.

EGCG stimulates the recruitment of brite adipocytes, suppresses adipogenesis and counteracts TNF-α-triggered insulin resistance in adipocytes

The global rise in obesity and type 2 diabetes has precipitated the need for therapeutic intervention in the arsenal against adiposity. (-)-Epigallocatechin-3-gallate (EGCG), a major nutraceutical component of green tea, has been regarded as a nutraceutical that has powerful antioxidant and anti-obesity bioactivities. In the present study, we showed that EGCG alleviates intracellular lipid accumulation markedly, and the inhibitory effect was largely limited to the early stage of adipocyte differentiation. Consistently, EGCG notably evoked the phosphorylation of AMPK and ACC and blunted the key enzymes of de novo lipogenesis. Interestingly, EGCG elicited iWAT-preadipocyte-derived mature white adipocyte beiging via activating thermogenic gene Ucp1 expression and mitochondrial biogenesis. Furthermore, our results also revealed that EGCG attenuated insulin signaling pathway blockage induced by TNF-α through the abrogation of redox imbalance and mitochondrial dysfunction. These findings indicate that EGCG is capable of suppressing adipogenesis and evoking white adipocyte beiging and therefore it may potentially serve as a novel approach to combat obesity.

GEOMetaCuration: a web-based application for accurate manual curation of Gene Expression Omnibus metadata

Abstract

Metadata curation has become increasingly important for biological discovery and biomedical research because a large amount of heterogeneous biological data is currently freely available. To facilitate efficient metadata curation, we developed an easy-to-use web-based curation application, GEOMetaCuration, for curating the metadata of Gene Expression Omnibus datasets. It can eliminate mechanical operations that consume precious curation time and can help coordinate curation efforts among multiple curators. It improves the curation process by introducing various features that are critical to metadata curation, such as a back-end curation management system and a curator-friendly front-end. The application is based on a commonly used web development framework of Python/Django and is open-sourced under the GNU General Public License V3. GEOMetaCuration is expected to benefit the biocuration community and to contribute to computational generation of biological insights using large-scale biological data. An example use case can be found at the demo website: http://geometacuration.yubiolab.org. Database URL: https://bitbucket.com/yubiolab/GEOMetaCuration

Mirabegron: potential off target effects and uses beyond the bladder

The β₃ -adrenoceptor was initially an attractive target for several pharmaceutical companies due to its high expression in rodent adipose tissue, where its activation resulted in decreased adiposity and improved metabolic outputs (such as glucose handling) in animal models of obesity and Type 2 diabetes. However, several drugs acting at the β₃ -adrenoceptor failed in clinical trials. This was thought to be due to their lack of efficacy at the human receptor. Recently, mirabegron, a β₃ -adrenoceptor agonist with human efficacy, was approved in North America, Europe, Japan and Australia for the treatment of overactive bladder syndrome. There are indications that mirabegron may act at other receptors/targets, but whether they have any clinical relevance is relatively unknown. Besides overactive bladder syndrome, mirabegron may have other uses such as in the treatment of heart failure or metabolic disease. This review gives an overview of the off-target effects of mirabegron and its potential use in the treatment of other diseases.

LINKED ARTICLES

This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.

Rosiglitazone and a β3-Adrenoceptor Agonist Are Both Required for Functional Browning of White Adipocytes in Culture

The recruitment of brite (or beige) adipocytes has been advocated as a means to combat obesity, due to their ability to phenotypically resemble brown adipocytes (BA). Lineage studies indicate that brite adipocytes are formed by differentiation of precursor cells or by direct conversion of existing white adipocytes, depending on the adipose depot examined. We have systematically compared the gene expression profile and a functional output (oxygen consumption) in mouse adipocytes cultured from two contrasting depots, namely interscapular brown adipose tissue, and inguinal white adipose tissue (iWAT), following treatment with a known browning agent, the peroxisome proliferator-activated receptor (PPARγ) activator rosiglitazone. Prototypical BA readily express uncoupling protein (UCP)1, and upstream regulators including the β₃-adrenoceptor and transcription factors involved in energy homeostasis. Adipocytes from inguinal WAT display maximal UCP1 expression and mitochondrial uncoupling only when treated with a combination of the PPARγ activator rosiglitazone and a β₃-adrenoceptor agonist. In conclusion, brite adipocytes are fully activated only when a browning agent (rosiglitazone) and a thermogenic agent (β₃-adrenoceptor agonist) are added in combination. The presence of rosiglitazone throughout the 7-day culture period partially masks the effects of β₃-adrenoceptor signaling in inguinal white adipocyte cultures, whereas including rosiglitazone only for the first 3 days promotes robust β₃-adrenoceptor expression and provides an improved window for detection of β₃-adrenoceptor responses.

Use of deep neural network ensembles to identify embryonic-fetal transition markers: repression of COX7A1 in embryonic and cancer cells

Here we present the application of deep neural network (DNN) ensembles trained on transcriptomic data to identify the novel markers associated with the mammalian embryonic-fetal transition (EFT). Molecular markers of this process could provide important insights into regulatory mechanisms of normal development, epimorphic tissue regeneration and cancer. Subsequent analysis of the most significant genes behind the DNNs classifier on an independent dataset of adult-derived and human embryonic stem cell (hESC)-derived progenitor cell lines led to the identification of COX7A1 gene as a potential EFT marker. COX7A1, encoding a cytochrome C oxidase subunit, was up-regulated in post-EFT murine and human cells including adult stem cells, but was not expressed in pre-EFT pluripotent embryonic stem cells or their in vitro-derived progeny. COX7A1 expression level was observed to be undetectable or low in multiple sarcoma and carcinoma cell lines as compared to normal controls. The knockout of the gene in mice led to a marked glycolytic shift reminiscent of the Warburg effect that occurs in cancer cells. The DNN approach facilitated the elucidation of a potentially new biomarker of cancer and pre-EFT cells, the embryo-onco phenotype, which may potentially be used as a target for controlling the embryonic-fetal transition.

Critical review of beige adipocyte thermogenic activation and contribution to whole-body energy expenditure

Beige (or brite, "brown in white") adipocytes are uncoupling protein 1 (UCP1)-positive cells residing in white adipose depots that, depending on the conditions, behave either as classic white adipocytes, storing energy as lipids, or as brown adipocytes, dissipating energy from oxidative metabolism as heat through non-shivering thermogenesis. Because of their thermogenic potential and, therefore, possible usage to treat metabolic diseases such as obesity and type 2 diabetes, beige cells have attracted the attention of many scientists worldwide aiming to develop strategies to safely recruit and activate their thermogenic activity. Indeed, in recent years, a large variety of conditions, molecules (including nutrients) and signaling pathways were reported to promote the recruitment of beige adipocytes. Despite of those advances, the true contribution of beige adipocyte thermogenesis to whole-body energy expenditure is still not completely defined. Herein, we discuss some important aspects that should be considered when studying beige adipocyte biology and the contribution to energy balance and whole-body metabolism.