The global perspective on peroxisome proliferator-activated receptor γ (PPARγ) in ectopic fat deposition: A review

Identification of an alternative ligand-binding pocket in peroxisome proliferator-activated receptor gamma and its correlated selective agonist for promoting beige adipocyte differentiation

The pharmacological activation of peroxisome proliferator-activated receptor gamma (PPARγ) is a convenient and promising strategy for promoting beige adipocyte biogenesis to combat obesity-related metabolic disorders. However, thiazolidinediones (TZDs), the full agonists of PPARγ exhibit severe side effects in animal models and in clinical settings. Therefore, the development of efficient and safe PPARγ modulators for the treatment of metabolic diseases is emerging. In this study, using comprehensive methods, we report a previously unidentified ligand-binding pocket (LBP) in PPARγ and link it to beige adipocyte differentiation. Further virtual screening of 4097 natural compounds based on this novel LBP revealed that saikosaponin A (NJT-2), a terpenoid compound, can bind to PPARγ to induce coactivator recruitment and effectively activate PPARγ-mediated transcription of the beige adipocyte program. In a mouse model, NJT-2 administration efficiently promoted beige adipocyte biogenesis and improved obesity-associated metabolic dysfunction, with significantly fewer adverse effects than those observed with TZD. Our results not only provide an advanced molecular insight into the structural ligand-binding details in PPARγ, but also develop a linked selective and safe agonist for obesity treatment.

Tea Polysaccharide Ameliorates High-Fat Diet-Induced Renal Tubular Ectopic Lipid Deposition via Regulating the Dynamic Balance of Lipogenesis and Lipolysis

Renal tubular ectopic lipid deposition (ELD) plays a significant role in the development of chronic kidney disease, posing a great threat to human health. The present work aimed to explore the intervention effect and potential molecular mechanism of a purified tea polysaccharide (TPS3A) on renal tubular ELD. The results demonstrated that TPS3A effectively improved kidney function and slowed the progression of tubulointerstitial fibrosis in high-fat-diet (HFD)-exposed ApoE-/- mice. Additionally, TPS3A notably suppressed lipogenesis and enhanced lipolysis, as shown by the downregulation of lipogenesis markers (SREBP-1 and FAS) and the upregulation of lipolysis markers (HSL and ATGL), thereby reducing renal tubular ELD in HFD-fed ApoE-/- mice and palmitic-acid-stimulated HK-2 cells. The AMPK-SIRT1-FoxO1 axis is a core signal pathway in regulating lipid deposition. Consistently, TPS3A significantly increased the levels of phosphorylated-AMPK, SIRT1, and deacetylation of Ac-FoxO1. However, these effects of TPS3A on lipogenesis and lipolysis were abolished by AMPK siRNA, SIRT1 siRNA, and FoxO1 inhibitor, resulting in exacerbated lipid deposition. Taken together, TPS3A shows promise in ameliorating renal tubular ELD by inhibiting lipogenesis and promoting lipolysis through the AMPK-SIRT1-FoxO1 signaling pathway.

Consumption of interesterified palm oil leads inflammation of white adipose tissue and triggers metabolic disturbances in mice on a high-fat diet

Growing obesity is linked to shifts in dietary patterns, particularly the increased intake of ultra-processed high-fat foods. This study aimed to evaluate the effects of interesterified palm oil consumption on glucose homeostasis, adipose tissue remodeling, and hepatic lipogenesis in C57BL/6 mice fed a high-fat diet. Sixty C57BL/6 mice were divided into four groups (n = 15): the control group (C) fed a standard diet (4% soybean oil), the high-fat group (HF) (23.8% lard), the high palm oil fat group (HFP) (23.8% palm oil), and the high interesterified palm fat group (HFI) (23.8% interesterified palm oil) for 8 weeks (all groups received 50% energy from lipids). The HFI group exhibited higher body mass than the HF group (+ 11%, P < 0.05), which was attributed to an increased percentage of fat mass. Plasma concentrations of IL-6, insulin, and HOMA-IR were also elevated in the HFI group. Both the HFP and HFI groups showed hypertrophied adipocytes and pancreatic islets, increased alpha and beta cell masses, hepatic steatosis, low expression of genes related to beta-oxidation, and upregulated lipogenesis. In conclusion, the consumption of interesterified palm oil alters inflammatory and glucose profiles.

Unraveling the rationale and conducting a comprehensive assessment of KD025 (Belumosudil) as a candidate drug for inhibiting adipogenic differentiation-a systematic review

Rho-associated kinases (ROCKs) are crucial during the adipocyte differentiation process. KD025 (Belumosudil) is a newly developed inhibitor that selectively targets ROCK2. It has exhibited consistent efficacy in impeding adipogenesis across a spectrum of in vitro models of adipogenic differentiation. Given the novelty of this treatment, a comprehensive systematic review has not been conducted yet. This systematic review aims to fill this knowledge void by providing readers with an extensive examination of the rationale behind KD025 and its impacts on adipogenesis. Preclinical evidence was gathered owing to the absence of clinical trials. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and the study's quality was assessed using the Joanna Briggs Institute (JBI) Checklist Critical Appraisal Tool for Systematic Reviews. In various in vitro models, such as 3T3-L1 cells, human orbital fibroblasts, and human adipose-derived stem cells, KD025 demonstrated potent anti-adipogenic actions. At a molecular level, KD025 had significant effects, including decreasing fibronectin (Fn) expression, inhibiting ROCK2 and CK2 activity, suppressing lipid droplet formation, and reducing the expression of proadipogenic genes peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα). Additionally, KD025 resulted in the suppression of fatty acid-binding protein 4 (FABP4 or AP2) expression, a decrease in sterol regulatory element binding protein 1c (SREBP-1c) and Glut-4 expression. Emphasis must be placed on the fact that while KD025 shows potential in preclinical studies and experimental models, extensive research is crucial to assess its efficacy, safety, and potential therapeutic applications thoroughly and directly in human subjects.

Microbe-derived Antioxidants Enhance Lipid Synthesis by Regulating the Hepatic AMPKα-SREBP1c Pathway in Weanling Piglets

BACKGROUND

Weaning usually causes low feed intake and weight loss in piglets, which mobilizes lipid to energize. The microbe-derived antioxidants (MAs) exhibit great potential in antioxidation, anti-inflammation, and metabolic regulation.

OBJECTIVES

We aimed to investigate the changes of lipid metabolism postweaning and effects of MA on growth performance and hepatic lipid metabolism in weanling piglets.

METHODS

In the first experiment, piglets weaned at 21 d of age were slaughtered on weaning day (d0), 4 (d4), and 14 (d14) postweaning (6 piglets per day). In the second experiment, piglets were divided into 2 groups, receiving MA (MA) and saline gavage (CON), respectively. All piglets were weaned at 21 d of age and 6 piglets from each group were slaughtered at 25 d of age.

RESULTS

In experiment 1, the serum triglyceride, total cholesterol (TC), and LDL cholesterol on d4 and d14 declined significantly compared with d0 (P < 0.05). The serum leptin on d0 was higher than that on d4 and d14 (P < 0.05). The serum ghrelin kept increasing from d0 to d14 (P < 0.05). The hepatic hormone-sensitive lipase and adipose triglyceride lipase first increased from d0 to d4 and then decreased from d4 to d14 (P < 0.05). In experiment 2, the average daily gain and average daily feed intake from 21 to 25 d of age increased in the MA group compared with the CON group (P < 0.05). The serum TC, hepatic TC, and glucose of MA group showed a significant increase than that of the CON group (P < 0.05). The expression of SCD1, ACAT2, and PPARγ were upregulated in the MA group (P < 0.05). Contrary to the decreased expression of phosphorylation of adenosine 5'-monophosphate-activated protein kinase alfa subunit (Thr172), the nuclear sterol regulatory element-binding protein 1c, fatty acid synthase, and peroxisome proliferator-activated receptor gamma of MA group increased than that of CON group (P < 0.05).

CONCLUSIONS

Weaning promoted hepatic lipolysis and MA could enhance lipid synthesis by regulating adenosine 5'-monophosphate-activated protein kinase alfa subunit-sterol regulatory element-binding protein 1c pathway, thus improving growth performance of weanling piglets.