Pharmacological targeting of adipocytes/fat metabolism for treatment of obesity and diabetes

Berberine: Pharmacological Features in Health, Disease and Aging

BACKGROUND

Berberine is the main active compound of different herbs and is defined as an isoquinoline quaternary botanical alkaloid found in barks and roots of numerous plants. It exhibits a wide range of pharmacological effects, such as anti-obesity and antidiabetic effects. Berberine has antibacterial activity against a variety of microbiota, including many bacterial species, protozoa, plasmodia, fungi, and trypanosomes.

OBJECTIVE

This review describes the role of berberine and its metabolic effects. It also discusses how it plays a role in glucose metabolism, fat metabolism, weight loss, how it modulates the gut microbiota, and what are its antimicrobial properties along with its potential side effects with maximal tolerable dosage.

METHODS

Representative studies were considered and analyzed from different scientific databases, including PubMed and Web of Science, for the years 1982-2022.

RESULTS

Literature analysis shows that berberine affects many biochemical and pharmacological pathways that theoretically yield a positive effect on health and disease. Berberine exhibits neuroprotective properties in various neurodegenerative and neuropsychological ailments. Despite its low bioavailability after oral administration, berberine is a promising tool for several disorders. A possible hypothesis would be the modulation of the gut microbiome. While the evidence concerning the aging process in humans is more limited, preliminary studies have shown positive effects in several models.

CONCLUSION

Berberine could serve as a potential candidate for the treatment of several diseases. Previous literature has provided a basis for scientists to establish clinical trials in humans. However, for obesity, the evidence appears to be sufficient for hands-on use.

Anti-obesity effects of galla rhois via genetic regulation of adipogenesis

In the present study, we investigated the effects of Galla Rhois (GR) on obesity and gene expression. We prepared a GR extract and various solvent fractions and evaluated the degree to which they inhibited adipocyte differentiation and adipogenesis in vitro. Among them, the GR ethyl acetate fraction (GE) had the lowest EC50 for adipocyte differentiation and adipogenesis and thus was selected for in vivo experiments. We induced obesity in C57BL/6 mice by providing them a high-fat diet (HFD). Then, GE (10-40 mg/kg) or orlistat (positive control, 4 mg/kg) was orally administered daily for six weeks. Mean body weights and weight gain were significantly lower in the GE40 group (40 mg/kg of GE) compared with the HFD group (p < 0.05). The most significant changes in serum glucose, total cholesterol, and triglyceride levels were confirmed in the GE40 group (p < 0.05). Epididymal fat was weighed and stained for body fat measurement, and significant differences were recorded from GE10 to GE40 (p < 0.05). Finally, 3T3-L1 pre-adipocytes were treated with GE, and cDNA from these cells was used for microarray analysis and qRT-PCR. Microarray analysis revealed 13 genes up-regulated and 21 genes down-regulated by GE. From the qRT-PCR analysis, we found that GE altered the mRNA expression of eosinophil peroxidase, glucose-dependent insulinotropic polypeptide receptor, and apolipoprotein B. Based on this study, we suggest that GR could be developed as an anti-obesity therapeutic agent.

Description of the unusual digestive tract of Platax orbicularis and the potential impact of Tenacibaculum maritimum infection

Background

Ephippidae fish are characterized by a discoid shape with a very small visceral cavity. Among them Platax orbicularis has a high economic potential due to its flesh quality and flesh to carcass ratio. Nonetheless, the development of its aquaculture is limited by high mortality rates, especially due to Tenacibaculum maritimum infection, occurring one to three weeks after the transfer of fishes from bio-secure land-based aquaculture system to the lagoon cages for growth. Among the lines of defense against this microbial infection, the gastrointestinal tract (GIT) is less studied. The knowledge about the morphofunctional anatomy of this organ in P. orbicularis is still scarce. Therefore, the aims of this study are to characterize the GIT in non-infected P. orbicularis juveniles to then investigate the impact of T. maritimum on this multifunctional organ.

Methods

In the first place, the morpho-anatomy of the GIT in non-infected individuals was characterized using various histological techniques. Then, infected individuals, experimentally challenged by T. maritimum were analysed and compared to the previously established GIT reference.

Results

The overlapped shape of the GIT of P. orbicularis is probably due to its constrained compaction in a narrow visceral cavity. Firstly, the GIT was divided into 10 sections, from the esophagus to the rectum. For each section, the structure of the walls was characterized, with a focus on mucus secretions and the presence of the Na⁺/K⁺ ATPase pump. An identification key allowing the characterization of the GIT sections using in toto histology is given. Secondly, individuals challenged with T. maritimum exhibited differences in mucus type and proportion and, modifications in the mucosal and muscle layers. These changes could induce an imbalance in the trade-off between the GIT functions which may be in favour of protection and immunity to the disadvantage of nutrition capacities.

Ezetimibe ameliorates lipid accumulation during adipogenesis by regulating the AMPK-mTORC1 pathway

Adipogenesis, a critical process that converts adipocyte precursors into adipocytes, is considered a potential therapeutic target for the treatment of obesity. Ezetimibe, a drug approved by the United States Food and Drug Administration, is used for the treatment of hypercholesterolemia. Recently, it was reported to ameliorate high fat diet-induced dyslipidemia in mice and reduce lipid accumulation in hepatocytes through the activation of AMPK. However, the anti-adipogenic effects of ezetimibe and the underlying molecular mechanism have not yet been elucidated. Here, we found that ezetimibe reduced lipid accumulation via activating AMPK during the early phase of adipogenesis. We also observed that ezetimibe inhibited peroxisome proliferator-activated receptor γ, which is a major transcription factor of adipogenesis. Furthermore, ezetimibe-mediated AMPK activation reduced lipid accumulation by inhibiting mTORC1 signaling, leading to the downregulation of lipogenesis-related genes. Mitotic clonal expansion, required for adipogenesis, accelerates cell cycle progression and cell proliferation. We additionally observed that ezetimibe prevented the progression of mitotic clonal expansion by arresting the cell cycle at the G0/G1 phase, which was followed by the inhibition of cell proliferation. Collectively, ezetimibe-mediated inhibition of adipogenesis is dependent on the AMPK-mTORC1 pathway. Thus, we suggest that ezetimibe might be a promising drug for the treatment of obesity.

Placental extract suppresses differentiation of 3T3-L1 preadipocytes to mature adipocytes via accelerated activation of p38 MAPK during the early phase of adipogenesis

Background

Adipogenesis, the process of preadipocyte differentiation to mature adipocytes accompanied by accumulation of intracytoplasmic lipid droplets, is regulated by various genetic and environmental factors, and closely associated with the development of obesity. Numerous recent studies suggest that some bioactive peptides and proteins derived from animals, and chemical compounds isolated from plants may be useful for prevention and treatment of obesity and obesity-related chronic diseases. In the present study, we examined the broad spectrum of effects of placental extract, with a focus on the influence of placental extract on adipogenesis.

Method

We cultured 3T3-L1 cells, which are widely used as a model of white preadipocytes, under differentiation conditions in the presence of porcine placental extract (PPE) for 8 days, and then stained the lipid droplets accumulated in the cytoplasm with Oil Red O. We also analyzed the effects of PPE on the mitogen-activated protein kinases (MAPKs) signaling, mitotic clonal expansion (MCE) and gene expressions associated with 3T3-L1 differentiation.

Results

When we cultured 3T3-L1 cells with PPE under differentiation conditions, the accumulation of lipid droplets and expression of adipocyte differentiation marker genes (Cebpa, Pparg, Slc2a4, Fasn and Adipoq) were dramatically attenuated. The suppressive activity of PPE against adipogenesis was heat-stable and recovered in a low-molecular-weight fraction after ultrafiltration (< 3 kDa) and gel-filtration chromatography (fraction No. 9). We also found that the suppressive activity of PPE affected the early phase of adipocyte differentiation (Days 0–2) without influencing the expression levels of C/EBPβ and C/EBPδ. The PPE and fraction No. 9 obtained from gel-filtration chromatography both promoted mitotic clonal expansion of 3T3-L1 while accelerating p38 MAPK phosphorylation. In addition, SB203580, a p38 MAPK inhibitor, partially restored the accumulation of lipid droplets and the expression of adipocyte differentiation marker genes that were suppressed by fraction No. 9.

Conclusion

These results indicate that PPE suppresses the differentiation of preadipocytes via accelerated activation of p38 MAPK during the early phase of adipogenesis, suggesting PPE or its functional component could be a potential therapy for treating obesity.

Electronic supplementary material

The online version of this article (10.1186/s12986-019-0361-8) contains supplementary material, which is available to authorized users.

Anti-obesity and hypolipidemic effect of water extract from Pleurotus citrinopileatus in C57BL/6J mice

Obesity has become one of the most important health problems worldwide requiring urgent need for efficient control. Pleurotus citrinopileatus (P. citrinopileatus)-a type of edible mushroom with abundant bioactive molecules-is a promising source for achieving this goal. In the present study, we evaluated the anti-obesity and hypolipidemic effect of P. citrinopileatus water extract (PWE) using a series of biochemical assays in randomized high-fat diet-induced obese (DIO) C57BL/6J mice, which were gavaged daily with low or high levels of PWE (400 or 800 mg/kg of body weight, respectively) in addition to high-fat diet for 12 weeks. Results showed that PWE significantly reduced the weight gain, fat accumulation, and food intake of DIO mice within 12 weeks. PWE also decreased the serum triglycerides, cholesterol and low-density lipoprotein, aspartate transaminase, nonesterified fatty acid, and creatinine, but increased high-density lipoprotein. Additionally, PWE improved the glucose tolerance of mice fed with high fat. From above, we conclude that PWE has great potential as functional foods for management of obesity and/or associated metabolic disorders.

Methyl gallate, a potent antioxidant inhibits mouse and human adipocyte differentiation and oxidative stress in adipocytes through impairment of mitotic clonal expansion

Methyl gallate (MG) is a derivative of gallic acid and a potent antioxidant. In this study, we confirmed that MG treatment effectively inhibits lipid accumulation, which occurred mostly in the early stages of adipogenesis. We also showed that shortly after adipogenic induction, MG facilitated a G0/G1 cell cycle arrest. Mechanistic studies revealed that MG treatment inhibited ERK1/2 phosphorylation, which is a key regulator of the G1- to S-phase transition. Furthermore, MG treatment prevented the adipogenic hormonal stimuli-induced inhibition of the cyclin-dependent kinase inhibitor p27^Kip1 . This led to inhibition of the transcription factor E2F1 by preventing the phosphorylation of, and thereby activation of its destruction partner RB. MG treatment also downregulated factors that are upstream of RB-E2F1 signaling such as Cdk2, Cyclin E, Cdk4, and Cyclin D1 where Cyclin D3 level was unaffected. We also found that MG treatment markedly decreased the expression and phosphorylation of C/EBPβ, by phosphorylating, and therefore inactivating, GSK3β, which is a prerequisite for its DNA binding capacity, and thereby mitotic clonal expansion (MCE). Ultimately, MG treatment downregulates key terminal adipogenic transcription factors including C/EBPα, PPARγ, aP2 (Fabp4), and adiponectin. Moreover, MG also protects adipocytes from oxidative stress by alleviating intracellular reactive oxygen species and activating Nrf2, HO-1, and PRDX3. Thus, this study provides a mechanistic insight into the anti-adipogenic actions of MG. © 2016 BioFactors, 42(6):716-726, 2016.

TNP [N2-(m-Trifluorobenzyl), N6-(p-nitrobenzyl)purine] ameliorates diet induced obesity and insulin resistance via inhibition of the IP6K1 pathway

Objective

Obesity and type 2 diabetes (T2D) lead to various life-threatening diseases such as coronary heart disease, stroke, osteoarthritis, asthma, and neurodegeneration. Therefore, extensive research is ongoing to identify novel pathways that can be targeted in obesity/T2D. Deletion of the inositol pyrophosphate (5-IP7) biosynthetic enzyme, inositol hexakisphosphate kinase-1 (IP6K1), protects mice from high fat diet (HFD) induced obesity (DIO) and insulin resistance. Yet, whether this pathway is a valid pharmacologic target in obesity/T2D is not known. Here, we demonstrate that TNP [N2-(m-Trifluorobenzyl), N6-(p-nitrobenzyl)purine], a pan-IP6K inhibitor, has strong anti-obesity and anti-diabetic effects in DIO mice.

Methods

Q-NMR, GTT, ITT, food intake, energy expenditure, QRT-PCR, ELISA, histology, and immunoblot studies were conducted in short (2.5-week)- and long (10-week)-term TNP treated DIO C57/BL6 WT and IP6K1-KO mice, under various diet and temperature conditions.

Results

TNP, when injected at the onset of HFD-feeding, decelerates initiation of DIO and insulin resistance. Moreover, TNP facilitates weight loss and restores metabolic parameters, when given to DIO mice. However, TNP does not reduce weight gain in HFD-fed IP6K1-KO mice. TNP specifically enhances insulin sensitivity in DIO mice via Akt activation. TNP decelerates weight gain primarily by enhancing thermogenic energy expenditure in the adipose tissue. Accordingly, TNP's effect on body weight is partly abolished whereas its impact on glucose homeostasis is preserved at thermoneutral temperature.

Conclusion

Pharmacologic inhibition of the inositol pyrophosphate pathway has strong therapeutic potential in obesity, T2D, and other metabolic diseases.

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Pharmacologic inhibition of IP6K by TNP, at the onset of high fat feeding, decelerates initiation of DIO and insulin resistance in mice.

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TNP, when treated to DIO mice, promotes weight loss and restores metabolic homeostasis.

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TNP does not reduce high fat diet induced weight gain in IP6K1-KO mice.

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TNP promotes insulin sensitivity by stimulating Akt activity, whereas it reduces body weight primarily by enhancing thermogenic energy expenditure.

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Long-term TNP treatment does not display deleterious side effects.

Sea cucumber and blue mussel: new sources of phospholipid enriched omega-3 fatty acids with a potential role in 3T3-L1 adipocyte metabolism

Sea cucumber and blue mussel methanolic extracts are enriched inn-3 polyunsaturated fatty acids structured in the phospholipid form, which increases adipogenesis and decreases lipogenesis in 3T3-L1 adipocytes.

Small‑molecule COH-SR4 inhibits adipocyte differentiation via AMPK activation

Obesity is a chronic metabolic disorder caused by an imbalance between energy intake and expenditure. It is one of the principal causative factors involved in the development of metabolic syndrome and cancer. Inhibition of adipocyte differentiation has often been a target of anti-obesity strategies since obesity is caused not only by hypertrophy but also by adipocyte hyperplasia. In this study, we investigated the effects of COH-SR4, a novel compound with anticancer properties, on the adipogenesis in 3T3-L1 cells. Treatment with COH-SR4 significantly inhibited adipocyte differentiation in a dose-dependent manner. This inhibitory effect mainly occurred at the early phase of differentiation through inhibition of mitotic clonal expansion and cell cycle arrest at the G1/S phase transition. In differentiating adipocytes, COH-SR4 significantly reduced intracellular lipid accumulation and downregulated the expression of key adipogenesis-related transcription factors and lipogenic proteins. COH-SR4 exhibited no cytotoxic effects in 3T3-L1 cells, but indirectly activated AMP-activated protein kinase (AMPK). AMPK activation by COH-SR4 also resulted in the phosphorylation of raptor and tuberous sclerosis protein 2 (TSC2), two proteins involved in the mammalian target of rapamycin (mTOR) signaling pathways. Additionally, COH-SR4 decreased the phosphorylation of p70 kDa ribosomal protein S6 kinase (S6K) and initiation factor 4E (eIF4E) binding protein 1 (4EB‑P1), two downstream effectors of mTOR that regulate protein synthesis. Interestingly, knockdown of AMPKα1/α2 prevented the ability of COH-SR4 to inhibit cell cycle arrest and overall adipogenesis and lipid accumulation in the differentiating 3T3-L1 cells. Taken together, these results suggest that COH-SR4 inhibits 3T3-L1 adipogenesis via AMPK activation. COH-SR4 may be a promising compound for the treatment of obesity and related metabolic disorders.

Control of lipid storage and cell size between adipocytes by vesicle-associated glycosylphosphatidylinositol-anchored proteins

Adipose tissue mass in mammals is expanding by increasing the average cell volume as well as the total number of the adipocytes. Up-regulation of lipid storage in fully differentiated adipocytes resulting in their enlargement is well documented and thought to be a critical mechanism for the expansion of adipose tissue depots during the growth of both lean and obese animals and human beings. A novel molecular mechanism for the regulation of lipid storage and cell size in rat adipocytes has recently been elucidated for the physiological stimuli, palmitate and hydrogen peroxide, the anti-diabetic sulfonylurea drug, glimepiride, and insulin-mimetic phosphoinositolglycans. It encompasses (i) the release of small vesicles, so-called adiposomes, harbouring the glycosylphosphatidylinositol-anchored (c)AMP-degrading phosphodiesterase Gce1 and 5'-nuceotidase CD73 from large donor adipocytes, (ii) the transfer of the adiposomes and their interaction with detergent-insoluble glycolipid-enriched microdomains of the plasma membrane of small acceptor adipocytes, (iii) the translocation of Gce1 and CD73 from the adiposomes to the intracellular lipid droplets of the acceptor adipocytes and (iv) the degradation of (c)AMP at the lipid droplet surface zone by Gce1 and CD73 in the acceptor adipocytes. In concert, this sequence of events leads to up-regulation of esterification of fatty acids into triacylglycerol and down-regulation of their release from triacylglycerol. This apparent mechanism for shifting the triacylglycerol burden from large to small adipocytes may provide novel strategies for the therapy of metabolic diseases, such as type 2 diabetes and obesity.

Lipid storage in large and small rat adipocytes by vesicle-associated glycosylphosphatidylinositol-anchored proteins

Adipose tissue mass in mammals expands by increasing the average cell volume and/or total number of the adipocytes. Upregulated lipid storage in fully differentiated adipocytes resulting in their enlargement is well documented and thought to be a critical mechanism for the expansion of adipose tissue depots during the growth of both lean and obese animals and human beings. A novel molecular mechanism for the regulation of lipid storage and cell size in rat adipocytes was recently elucidated for the physiological stimuli, palmitate and H(2)O(2), and the antidiabetic sulfonylurea drug, glimepiride. It encompasses (1) the release of small vesicles, so-called adiposomes, harboring the glycosylphosphatidylinositol -anchored (c)AMP-degrading phosphodiesterase Gce1 and 5'-nucleotidase CD73 from donor adipocytes, (2) the transfer of the adiposomes and their interaction with detergent-insoluble glycolipid-enriched microdomains of the plasma membrane of acceptor adipocytes, (3) the translocation of Gce1 and CD73 from the adiposomes to the intracellular lipid droplets of the acceptor adipocytes, and (4) the degradation of (c)AMP at the lipid droplet surface zone by Gce1 and CD73 in the acceptor adipocytes, leading to the upregulation of the esterification of fatty acids into triacylglycerol s and the downregulation of their release from triacylglycerols. This mechanism may provide novel strategies for the therapy of metabolic diseases, such as type 2 diabetes and obesity.

Berberine inhibits adipogenesis in high-fat diet-induced obesity mice

Our previous studies illustrated that berberine inhibited adipogenesis in murine-derived 3T3-L1 preadipocytes and human white preadipocytes. In this study, the effects of berberine on the adipogenesis of high-fat diet-induced obesity (FD) or normal diet (ND) mice and possible transcriptional impact are investigated. The results demonstrated that in FD mice, berberine reduced mouse weight gain and food intake and serum glucose, triglyceride, and total cholesterol levels accompanied with a down-regulation of PPARgamma expression and an up-regulation of GATA-3 expression. Berberine had no adverse effects on ND mice. These encouraging findings suggest that berberine has excellent pharmacological potential to prevent obesity.

Mitochondrial (dys)function in adipocyte (de)differentiation and systemic metabolic alterations

In mammals, adipose tissue, composed of BAT and WAT, collaborates in energy partitioning and performs metabolic regulatory functions. It is the most flexible tissue in the body, because it is remodeled in size and shape by modifications in adipocyte cell size and/or number, depending on developmental status and energy fluxes. Although numerous reviews have focused on the differentiation program of both brown and white adipocytes as well as on the pathophysiological role of white adipose tissues, the importance of mitochondrial activity in the differentiation or the dedifferentiation programs of adipose cells and in systemic metabolic alterations has not been extensively reviewed previously. Here, we address the crucial role of mitochondrial functions during adipogenesis and in mature adipocytes and discuss the cellular responses of white adipocytes to mitochondrial activity impairment. In addition, we discuss the increase in scientific knowledge regarding mitochondrial functions in the last 10 years and the recent suspicion of mitochondrial dysfunction in several 21st century epidemics (ie, obesity and diabetes), as well as in lipodystrophy found in HIV-treated patients, which can contribute to the development of new therapeutic strategies targeting adipocyte mitochondria.

FOXO-binding partners: it takes two to tango

Modulation FOXO transcription factor activities can lead to a variety of cellular outputs resulting in changes in proliferation, apoptosis, differentiation and metabolic responses. Although FOXO proteins all contain an identical DNA-binding domain their cellular functions appear to be distinct, as exemplified by differences in the phenotype of Foxo1, Foxo3 and Foxo4 null mutant mice. While some of these differences may be attributable to the differential expression patterns of these transcription factors, many cells and tissues express several FOXO isoforms. Recently it has become clear that FOXO proteins can regulate transcriptional responses independently of direct DNA-binding. It has been demonstrated that FOXOs can associate with a variety of unrelated transcription factors, regulating activation or repression of diverse target genes. The complement of transcription factors expressed in a particular cell type is thus critical in determining the functional end point of FOXO activity. These interactions greatly expand the possibilities for FOXO-mediated regulation of transcriptional programmes. This review details currently described FOXO-binding partners and examines the role of these interactions in regulating cell fate decisions.

One-step intracellular triglycerides extraction and quantitative measurement in vitro

INTRODUCTION

Measurement of intracellular triglyceride content is traditionally performed using Oil Red O stain and isopropanol extraction. However, the assay is semi-quantitative and its simplicity needs improving. Therefore, a novel assay is described to address these problems.

METHODS

Intracellular triglycerides (TG) were extracted directly by organic solvent Dimethyl Sulfoxide (DMSO) without stain. TG concentration dissolved in DMSO was subsequently measured with a commercial assay kit.

RESULTS

A series of experiments were conducted to verify the validity of the new protocol such as the extraction efficiency of DMSO, linear range of the kit and sensitivity of the assay. Our results suggest that this novel assay may be applied in the measurement of intracellular triglyceride accumulation induced by pre-adipocyte differentiation or compounds such as peroxisome proliferator-activated receptor gamma (PPARgamma) agonists.

CONCLUSION

The simplicity and efficiency of the method were validated in this study. Our findings show that this novel assay has potential application in the discovery of anti-diabetic compounds or in the research of cell TG metabolism.