Methylation of Hypothalamic Tsc1-mTOR Signaling in Regulation of Obesity and Obesity Resistance

Increased FGF-21 Improves Ectopic Lipid Deposition in the Liver and Skeletal Muscle

Obesity can lead to excessive lipid accumulation in non-adipose tissues, such as the liver and skeletal muscles, leading to ectopic lipid deposition and damaging target organ function through lipotoxicity. FGF-21 is a key factor in regulating lipid metabolism, so we aim to explore whether FGF-21 is involved in improving ectopic lipid deposition. We observed the characteristics of ectopic lipid deposition in the liver and skeletal muscles of obesity-resistant mice, detected the expression of FGF-21 and perilipin, and found that obesity-resistant mice showed a decrease in ectopic lipid deposition in the liver and skeletal muscles and increased expression of FGF-21. After inhibiting the expression of FGF-21, a more severe lipid deposition in liver cells and skeletal muscle cells was found. The results indicate that inhibiting FGF-21 can exacerbate ectopic lipid deposition via regulating lipid droplet synthesis and decomposition, as well as free fatty acid translocation and oxidation. In conclusion, FGF-21 is involved in improving ectopic lipid deposition caused by obesity in the liver and skeletal muscles.

Alisol B 23-acetate promotes white adipose tissue browning to mitigate high-fat diet-induced obesity by regulating mTOR-SREBP1 signaling

OBJECTIVE

Obesity is a global health concern with management strategies encompassing bariatric surgery and anti-obesity drugs; however, concerns regarding complexities and side effects persist, driving research for more effective, low-risk strategies. The promotion of white adipose tissue (WAT) browning has emerged as a promising approach. Moreover, alisol B 23-acetate (AB23A) has demonstrated efficacy in addressing metabolic disorders, suggesting its potential as a therapeutic agent in obesity management. Therefore, in this study, we aimed to investigate the therapeutic potential of AB23A for mitigating obesity by regulating metabolic phenotypes and lipid distribution in mice fed a high-fat diet (HFD).

METHODS

An obesity mouse model was established by administration of an HFD. Glucose and insulin metabolism were assessed via glucose and insulin tolerance tests. Adipocyte size was determined using hematoxylin and eosin staining. The expression of browning markers in WAT was evaluated using Western blotting and quantitative real-time polymerase chain reaction. Metabolic cage monitoring involved the assessment of various parameters, including food and water intake, energy metabolism, respiratory exchange rates, and physical activity. Moreover, oil red O staining was used to evaluate intracellular lipid accumulation. A bioinformatic analysis tool for identifying the molecular mechanisms of traditional Chinese medicine was used to examine AB23A targets and associated signaling pathways.

RESULTS

AB23A administration significantly reduced the weight of obese mice, decreased the mass of inguinal WAT, epididymal WAT, and perirenal adipose tissue, improved glucose and insulin metabolism, and reduced adipocyte size. Moreover, treatment with AB23A promoted the expression of browning markers in WAT, enhanced overall energy metabolism in mice, and had no discernible effect on food intake, water consumption, or physical activity. In 3T3-L1 cells, AB23A inhibited lipid accumulation, and both AB23A and rapamycin inhibited the mammalian target of rapamycin-sterol regulatory element-binding protein-1 (mTOR-SREBP1) signaling pathway. Furthermore, 3-isobutyl-1-methylxanthine, dexamethasone and insulin, at concentrations of 0.25 mmol/L, 0.25 μmol/L and 1 μg/mL, respectively, induced activation of the mTOR-SREBP1 signaling pathway, which was further strengthened by an mTOR activator MHY1485. Notably, MHY1485 reversed the beneficial effects of AB23A in 3T3-L1 cells.

CONCLUSION

AB23A promoted WAT browning by inhibiting the mTOR-SREBP1 signaling pathway, offering a potential strategy to prevent obesity. Please cite this article as: Han LL, Zhang X, Zhang H, Li T, Zhao YC, Tian MH, Sun FL, Feng B. Alisol B 23-acetate promotes white adipose tissue browning to mitigate high-fat diet-induced obesity by regulating mTOR-SREBP1 signaling. J Integr Med. 2024; 22(1): 83-92.

Epigenotoxicity: a danger to the future life

Environmental toxicants can regulate gene expression in the absence of DNA mutations via epigenetic mechanisms such as DNA methylation, histone modifications, and non-coding RNAs' (ncRNAs). Here, all three epigenetic modifications for seven important categories of diseases and the impact of eleven main environmental factors on epigenetic modifications were discussed. Epigenetic-related mechanisms are among the factors that could explain the root cause of a wide range of common diseases. Its overall impression on the development of diseases can help us diagnose and treat diseases, and besides, predict transgenerational and intergenerational effects. This comprehensive article attempted to address the relationship between environmental factors and epigenetic modifications that cause diseases in different categories. The studies main gap is that the precise role of environmentally-induced epigenetic alterations in the etiology of the disorders is unknown; thus, still more well-designed researches need to be accomplished to fill this gap. The present review aimed to first summarize the adverse effect of certain chemicals on the epigenome that may involve in the onset of particular disease based on in vitro and in vivo models. Subsequently, the possible adverse epigenetic changes that can lead to many human diseases were discussed.

Targeting mTOR Signaling by Dietary Polyphenols in Obesity Prevention

Dietary polyphenols can be utilized to treat obesity and chronic disorders linked to it. Dietary polyphenols can inhibit pre-adipocyte proliferation, adipocyte differentiation, and triglyceride accumulation; meanwhile, polyphenols can also stimulate lipolysis and fatty acid β-oxidation, but the molecular mechanisms of anti-obesity are still unclear. The mechanistic target of rapamycin (mTOR) is a protein kinase that regulates cell growth, survival, metabolism, and immunity. mTOR signaling is also thought to play a key role in the development of metabolic diseases such as obesity. Recent studies showed that dietary polyphenols could target mTOR to reduce obesity. In this review, we systematically summarized the research progress of polyphenols in preventing obesity through the mTOR signaling pathway. Mechanistically, polyphenols can target multiple signaling pathways and gut microbiota to regulate the mTOR signaling pathway to exert anti-obesity effects. The main mechanisms include: modulating lipid metabolism, adipogenesis, inflammation, etc. Dietary polyphenols exerting an anti-obesity effect by targeting mTOR signaling will broaden our understanding of the anti-obesity mechanisms of polyphenols and provide valuable insights for researchers in this novel field.

Electroacupuncture induces weight loss by regulating tuberous sclerosis complex 1-mammalian target of rapamycin methylation and hypothalamic autophagy in high-fat diet-induced obese rats

Background: Obesity can be caused by abnormalities of hypothalamic autophagy, which is closely regulated by the epigenetic modification of TSC1-mTOR. However, whether the weight-reducing effect of EA may relate to the modification of TSC1-mTOR methylation and hypothalamic autophagy remain unclear. This study was conducted to reveal the possible mechanism by which EA reduces BW by measuring the levels of TSC1-mTOR methylation and hypothalamic autophagy-related components.

Methods: The weight-reducing effect of EA was investigated in high-fat diet (HFD)-induced obese (DIO) rats by monitoring the BW, food consumption, and epididymal white adipose tissue (eWAT)/BW ratio. Hematoxylin and eosin staining was performed for morphological evaluation of eWAT. Immunofluorescence was utilized to observe the localization of LC3 in the hypothalamus. The expressions of autophagy components (Beclin-1, LC3, and p62) and mTOR signaling (mTOR, p-mTOR, p70S6K, and p-p70S6K) were assessed by western blot. The methylation rate of the TSC1 promoter was detected by bisulfite genomic sequencing.

Results: Treatment with EA significantly reduced the BW, food consumption, and eWAT/BW ratio; attenuated the morphological alternations in the adipocytes of DIO rats. While HFD downregulated the expression levels of Beclin-1 and LC3 and upregulated those of p62, these changes were normalized by EA treatment. EA markedly decreased the methylation rate of the TSC1 gene promoter and suppressed the protein expressions of mTOR, p-mTOR, p70S6K, and p-p70S6K in the hypothalamus.

Conclusion: EA could reduce BW and fat accumulation in DIO rats. This ameliorative effect of EA may be associated with its demethylation effect on TSC1-mTOR and regulation of autophagy in the hypothalamus.

All-in-one theranostic nano-platform based on polymer nanoparticles for BRET/FRET-initiated bioluminescence imaging and synergistically anti-inflammatory therapy for ulcerative colitis

Background

Ulcerative colitis (UC), a subtype of inflammatory bowel disease (IBD), has evolved into a global burden given its high incidence. There is a clinical need to create better diagnostic and therapeutic approaches to UC.

Results

We fabricated P-selectin binding peptide-decorated poly lactic-co-glycolic acid (PBP-PLGA-NP) doped with two lipophilic dyes, DiL and DiD. Meanwhile, two low-toxic anti-inflammatory natural products (betulinic acid [BA] and resveratrol [Res]) were co-loaded in the PBP-PLGA-NP system. The BA/Res-loaded NPs had an average size of around 164.18 nm with a negative zeta potential (− 25.46 mV). Entrapment efficiencies of BA and Res were 74.54% and 52.33%, respectively, and presented a sustained drug release profile. Further, the resulting PBP-PLGA-NP could be internalized by RAW 264.7 cells and Colon-26 cells efficiently in vitro and preferentially localized to the inflamed colon. When intravenously injected with luminol, MPO-dependent bioluminescence imaging to visualize tissue inflammation was activated by the bioluminescence and fluorescence resonance energy transfer (BRET-FRET) effect. Importantly, injected NPs could remarkably alleviate UC symptoms yet maintain intestinal microbiota homeostasis without inducing organ injuries in the mice models of colitis.

Conclusions

This theranostic nano-platform not only serves as a therapeutic system for UC but also as a non-invasive and highly-sensitive approach for accurately visualizing inflammation.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01299-8.

Jian Pi Tiao Gan Yin alleviates obesity phenotypes through mTORC1/SREBP1 signaling in vitro and in vivo

Background

Obesity has been considered as a leading cause of multiple metabolic syndromes, such as type 2 diabetes and hypertension cardiovascular diseases. Jian Pi Tiao Gan Yin (JPTGY), a Chinese herb preparation, is used to treat obesity of liver qi stagnation and spleen deficiency. The mechanism of action of JPTGY in obesity remains unclear. This study evaluated the effect of JPTGY on obesity.

Methods

The mechanism of action of JPTGY on obesity was investigated in high-fat diet (HFD)-induced obese mice and palmitic acid-treated 3T3-L1 cells. Lipid droplet accumulation was detected using oil red O staining. Factors associated with lipid accumulation were detected by western blotting.

Results

Treatment with JPTGY reduced HFD-induced adiposity and body weight gain. JPTGY increased the levels of brown adipose tissue biomarkers in obese mice and palmitic acid-treated 3T3-L1 cells, including peroxisome proliferator-activated receptor gamma coactivator-1-alpha (PGC-1α) and uncoupling protein-1 (UCP-1). Meanwhile, the protein expression of white adipose tissue biomarkers, such as AGT, primary subtalar arthrodesis (PSTA), and endothelin receptor type A (EDNRA), was decreased in obese mice and palmitic acid-treated 3T3-L1 cells. JPTGY affects browning of 3T3-L1 cells through mechanistic target of rapamycin complex 1 (mTORC1) signaling. JPTGY decreased the expression levels of key adipogenic-specific proteins and lipogenic enzymes, including peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), sterol regulatory element binding protein (SREBP), and FAS. Treatment with the mTOR activator MHY reversed JPTGY-mediated protein expression.

Conclusions

We concluded that JPTGY relieved obesity phenotypes through mTORC1/SREBP1 signaling in vitro and in vivo. JPTGY may benefit the attenuation of obesity.

In vitro characterization of subventricular zone isolated neural stem cells, from adult monkey and rat brain

Neural stem cells (NSCs) are multipotent, self-renewable cells who are capable of differentiating into neurons, astrocytes, and oligodendrocytes. NSCs reside at the subventricular zone (SVZ) of the adult brain permanently to guarantee a lifelong neurogenesis during neural network plasticity or undesirable injuries. Although the specious inaccessibility of adult NSCs niche hampers their in vivo identification, researchers have been seeking ways to optimize adult NSCs isolation, expansion, and differentiation, in vitro. NSCs were isolated from rhesus monkey SVZ, expanded in vitro and then characterized for NSCs-specific markers expression by immunostaining, real-time PCR, flow cytometry, and cell differentiation assessments. Moreover, cell survival as well as self-renewal capacity were evaluated by TUNEL, Live/Dead and colony assays, respectively. In the next step, to validate SVZ-NSCs identity in other species, a similar protocol was applied to isolate NSCs from adult rat's SVZ as well. Our findings revealed that isolated SVZ-NSCs from both monkey and rat preserve proliferation capacity in at least nine passages as confirmed by Ki67 expression. Additionally, both SVZ-NSCs sources are capable of self-renewal in addition to NESTIN, SOX2, and GFAP expression. The mortality was measured meager with over 95% viability according to TUNEL and Live/Dead assay results. Eventually, the multipotency of SVZ-NSCs appraised authentic after their differentiation into neurons, astrocytes, and oligodendrocytes. In this study, we proposed a reliable method for SVZ-NSCs in vitro maintenance and identification, which, we believe is a promising cell source for therapeutic approach to recover neurological disorders and injuries condition.

Prdm16-Mediated Browning is Involved in Resistance to Diet-Induced and Monosodium Glutamate-Induced Obesity

PURPOSE

To investigate resistance to diet-induced obesity (DIO) and monosodium glutamate (MSG)-induced obesity as well as the underlying mechanisms.

METHODS

Newborn mice were used to construct DIO and MSG-induced obesity models. Obesity indices, such as body weight, body length, Lee index, body temperature, food intake, fat weight, and leptin level, were examined. Mice that did not exhibit obesity were defined as the obesity-resistant group. The morphological changes of white adipose tissue were observed by hematoxylin and eosin staining, and expression levels of PR domain containing 16 (Prdm16) and uncoupling protein-1 (Ucp-1) in white adipose tissue were measured by Western blot.

RESULTS

Obesity-resistant mice fed a high-fat diet showed resistance beginning at week 5 along with lower weights and lengths than those in the obesity group from weeks 5 to 12. MSG-induced obesity-resistant mice showed features consistent with resistance to obesity from week 1 along with higher body lengths relative to the obesity group; however, the weight difference was not significant until week 10, when body weights decreased significantly in obesity-resistant mice. The Lee index was lower in obesity-resistant mice than in the obesity group and the normal group, further suggesting obesity resistance. Additionally, obesity-resistant mice showed higher levels of leptin, whereas obese mice induced by a high-fat diet showed leptin resistance. Furthermore, Prdm16 and Ucp-1 levels were both downregulated in the obesity group and upregulated in obesity-resistant mice, showing that white fat browning was highest in obesity-resistant mice.

CONCLUSION

The phenotypes of mice with DIO and MSG-induced obesity differed. Obesity resistance might be related to Prdm16 and Ucp-1-mediated white adipocyte browning.