Discovery of a potent FKBP38 agonist that ameliorates HFD-induced hyperlipidemia via mTOR/P70S6K/SREBPs pathway

Hypolipidemic effect and gut microbiota regulation of Gypenoside aglycones in rats fed a high-fat diet

ETHNOPHARMACOLOGICAL RELEVANCE

Gynostemma pentaphyllum (Thunb.) Makino has traditional applications in Chinese medicine to treat lipid abnormalities. Gypenosides (GPs), the main bioactive components of Gynostemma pentaphyllum, have been reported to exert hypolipidemic effects through multiple mechanisms. The lipid-lowering effects of GPs may be attributed to the aglycone portion resulting from hydrolysis of GPs by the gut microbiota. However, to date, there have been no reports on whether gypenoside aglycones (Agl), the primary bioactive constituents, can ameliorate hyperlipidemia by modulating the gut microbiota.

AIM OF THE STUDY

This study explored the potential therapeutic effects of gypenoside aglycone (Agl) in a rat model of high-fat diet (HFD)-induced hyperlipidemia.

METHODS

A hyperlipidemic rat model was established by feeding rats with a high-fat diet. Agl was administered orally, and serum lipid levels were analyzed. Molecular techniques, including RT-polymerase chain reaction (PCR) and fecal microbiota sequencing, were used to investigate the effects of Agl on lipid metabolism and gut microbiota composition.

RESULTS

Agl administration significantly reduced serum levels of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) and mitigated hepatic damage induced by HFD. Molecular investigations have revealed the modulation of key lipid metabolism genes and proteins by Agl. Notably, Agl treatment enriched the gut microbiota with beneficial genera, including Lactobacillus, Akkermansia, and Blautia and promoted specific shifts in Lactobacillus murinus, Firmicutes bacterium CAG:424, and Allobaculum stercoricanis.

CONCLUSION

This comprehensive study established Agl as a promising candidate for the treatment of hyperlipidemia. It also exhibits remarkable hypolipidemic and hepatoprotective properties. The modulation of lipid metabolism-related genes, along with the restoration of gut microbiota balance, provides mechanistic insights. Thus, Agl has great potential for clinical applications in hyperlipidemia management.

Alisol B regulates AMPK/mTOR/SREBPs via directly targeting VDAC1 to alleviate hyperlipidemia

BACKGROUND

The occurrence of hyperlipidemia is significantly influenced by lipid synthesis, which is regulated by sterol regulatory element binding proteins (SREBPs), thus the development of drugs that inhibit lipid synthesis has become a popular treatment strategy for hyperlipidemia. Alisol B (ALB), a triterpenoid compound extracted from Alisma, has been reported to ameliorate no-nalcoholic steatohepatitis (NASH) and slow obesity. However, the effect of ALB on hyperlipidemia and mechanism are unclear.

PURPOSE

To examine the therapeutic impact of ALB on hyperlipidemia whether it inhibits SREBPs to reduce lipid synthesis.

STUDY DESIGN

HepG2, HL7702 cells, and C57BL/6J mice were used to explore the effect of ALB on hyperlipidemia and the molecular mechanism in vivo and in vitro.

METHODS

Hyperlipidemia models were established using western diet (WD)-fed mice in vivo and oleic acid (OA)-induced hepatocytes in vitro. Western blot, real-time PCR and other biological methods verified that ALB regulated AMPK/mTOR/SREBPs to inhibit lipid synthesis. Cellular thermal shift assay (CETSA), molecular dynamics (MD), and ultrafiltration-LC/MS analysis were used to evaluate the binding of ALB to voltage-dependent anion channel protein-1 (VDAC1).

RESULTS

ALB decreased TC, TG, LDL-c, and increased HDL-c in blood, thereby ameliorating liver damage. Gene set enrichment analysis (GSEA) indicated that ALB inhibited the biosynthesis of cholesterol and fatty acids. Consistently, ALB inhibited the protein expression of n-SREBPs and downstream genes. Mechanistically, the impact of ALB on SREBPs was dependent on the regulation of AMPK/mTOR, thereby impeding the transportation of SREBPs from endoplasmic reticulum (ER) to golgi apparatus (GA). Further investigations indicated that the activation of AMPK by ALB was independent on classical upstream CAMKK2 and LKB1. Instead, ALB resulted in a decrease in ATP levels and an increase in the ratios of ADP/ATP and AMP/ATP. CETSA, MD, and ultrafiltration-LC/MS analysis indicated that ALB interacted with VDAC1. Molecular docking revealed that ALB directly bound to VDAC1 by forming hydrogen bonds at the amino acid sites S196 and H184 in the ATP-binding region. Importantly, the thermal stabilization of ALB on VDAC1 was compromised when VDAC1 was mutated at S196 and H184, suggesting that these amino acids played a crucial role in the interaction.

CONCLUSION

Our findings reveal that VDAC1 serves as the target of ALB, leading to the inhibition of lipid synthesis, presents potential target and candidate drugs for hyperlipidemia.

Discovery of Oral AMP-Activated Protein Kinase Activators for Treating Hyperlipidemia

Activation of AMP-activated protein kinase (AMPK) is proposed to alleviate hyperlipidemia. With cordycepin and N6-(2-hydroxyethyl) adenosine (HEA) as lead compounds, a series of adenosine-based derivatives were designed, synthesized, and evaluated on activation of AMPK. Finally, compound V1 was identified as a potent AMPK activator with the lipid-lowering effect. Molecular docking and circular dichroism indicated that V1 exerted its activity by binding to the γ subunit of AMPK. V1 markedly decreased the serum low-density lipoprotein cholesterol levels in C57BL/6 mice, golden hamsters, and rhesus monkeys. V1 was selected as the clinical compound and concluded Phase 1 clinical trials. A single dose of V1 (2000 mg) increased AMPK activation in human erythrocytes after 5 and 12 h of treatment. RNA sequencing data suggested that V1 downregulated expression of genes involved in regulation of apoptotic process, lipid metabolism, endoplasmic reticulum stress, and inflammatory response in liver by activating AMPK.

The beneficial health effects of puerarin in the treatment of cardiovascular diseases: from mechanisms to therapeutics

Cardiovascular diseases (CVDs) are the leading causes of death globally that seriously threaten human health. Although novel western medicines have continued to be discovered over the past few decades to inhibit the progression of CVDs, new drug research and development for treating CVDs with less side effects and adverse reactions are continuously being desired. Puerarin is a natural product found in a variety of medicinal plants belonging to the flavonoid family with potent biological and pharmacological activities. Abundant research findings in the literature have suggested that puerarin possesses a promising prospect in treating CVDs. In recent years, numerous new molecular mechanisms of puerarin have been explored in experimental and clinical studies, providing new evidence for this plant metabolite to protect against CVDs. This article systematically introduces the history of use, bioavailability, and various dosage forms of puerarin and further summarizes recently published data on the major research advances and their underlying therapeutic mechanisms in treating CVDs. It may provide references for researchers in the fields of pharmacology, natural products, and internal medicine.

The Effect of Guisangyou Tea on Abnormal Lipid Metabolism in Mice Induced by High-Fat Diet

This study was aimed to investigate the effect of Guisangyou tea (GSY tea) in improving abnormal lipid metabolism in mice with obesity induced by a high-fat diet (HFD). The results showed that intervention of the water extract of GSY tea (WE) decreased serum levels of lipids, and positively regulated the related antioxidant enzyme activities and the inflammatory factors in the serum and liver. In the liver, the mRNA and protein expression levels of sterol regulatory element-binding proteins-1 (SREBP-1), stearoyl-CoA desaturase-1 (SCD-1), fatty acid synthase (FASN), and acetyl CoA carboxylase (ACC) related to lipid synthesis were downregulated, and the mRNA and protein expression levels of the farnesoid X receptor (FXR) and small heterodimer partner (SHP) related to bile acid production were upregulated. The results demonstrate that GSY tea can improve abnormal lipid metabolism in obese mice by improving the body's antioxidant capacity, regulating the inflammatory state, and reducing the synthesis of lipids and increasing the production of bile acids. GSY tea can be processed and utilized as a safe and effective resource for improving abnormal lipid metabolism.

Analysis of Dysferlin Direct Interactions with Putative Repair Proteins Links Apoptotic Signaling to Ca2+ Elevation via PDCD6 and FKBP8

Quantitative surface plasmon resonance (SPR) was utilized to determine binding strength and calcium dependence of direct interactions between dysferlin and proteins likely to mediate skeletal muscle repair, interrupted in limb girdle muscular dystrophy type 2B/R2. Dysferlin canonical C2A (cC2A) and C2F/G domains directly interacted with annexin A1, calpain-3, caveolin-3, affixin, AHNAK1, syntaxin-4, and mitsugumin-53, with cC2A the primary target and C2F lesser involved, overall demonstrating positive calcium dependence. Dysferlin C2 pairings alone showed negative calcium dependence in almost all cases. Like otoferlin, dysferlin directly interacted via its carboxy terminus with FKBP8, an anti-apoptotic outer mitochondrial membrane protein, and via its C2DE domain with apoptosis-linked gene (ALG-2/PDCD6), linking anti-apoptosis with apoptosis. Confocal Z-stack immunofluorescence confirmed co-compartmentalization of PDCD6 and FKBP8 at the sarcolemmal membrane. Our evidence supports the hypothesis that prior to injury, dysferlin C2 domains self-interact and give rise to a folded, compact structure as indicated for otoferlin. With elevation of intracellular Ca2+ in injury, dysferlin would unfold and expose the cC2A domain for interaction with annexin A1, calpain-3, mitsugumin 53, affixin, and caveolin-3, and dysferlin would realign from its interactions with PDCD6 at basal calcium levels to interact strongly with FKBP8, an intramolecular rearrangement facilitating membrane repair.

Ultra-high performance liquid chromatography-quadrupole/time-of-flight mass spectrometry-based lipidomics reveals key lipid molecules as potential therapeutic targets of Polygonum cuspidatum against hyperlipidemia in a hamster model

Polygonum cuspidatum is a homology of traditional medicine and functional food widely distributed around the world. Our previous study on the hyperlipidemic animal model demonstrated that Polygonum cuspidatum was effective in ameliorating hyperlipidemia, which is characterized by lipid disorders. Herein, the regulatory effect of Polygonum cuspidatum on lipid metabolism needs to be known if its hypolipidemic mechanism is desired to clarify. In this study, an ultra-high performance liquid chromatography-quadrupole/time-of-flight mass spectrometry-based lipidomic strategy was first applied to investigate the lipidomic patterns of high-fat diet-induced hyperlipidemic hamsters when treated with Polygonum cuspidatum. The results showed that Polygonum cuspidatum improved the lipidomic profile of hyperlipidemia. A total of 65 differential lipids related to the hypolipidemic effect of Polygonum cuspidatum were screened out and identified, and these differential lipids covered various categories, such as phosphatidylcholines, phosphatidylethanolamines, triacylglycerols, sphingomyelins and so on. Orally administrated Polygonum cuspidatum restored these differential lipids back to normal or nearly normal levels. This study adopted lipidomics to reveal the key lipid molecules as potential therapeutic targets of Polygonum cuspidatum against hyperlipidemia, which would provide a scientific basis for its clinical application.

PPARγ/mTOR Regulates the Synthesis and Release of Prostaglandins in Ovine Trophoblast Cells in Early Pregnancy

Trophoblast cells synthesize and secrete prostaglandins (PGs), which are essential for ruminants in early gestation to recognize pregnancy. Hormones in the intrauterine environment play an important role in regulating PGs synthesis during implantation, but the underlying mechanism remains unclear. In this study, co-treatment of sheep trophoblast cells (STCs) with progesterone (P4), estradiol (E2), and interferon-tau (IFN-τ) increased the ratio of prostaglandin E2 (PGE2) to prostaglandin F2α (PGF2α) and upregulated peroxisome proliferator-activated receptor γ (PPARγ) expression, while inhibiting the mechanistic target of rapamycin (mTOR) pathway and activating cellular autophagy. Under hormone treatment, inhibition of PPARγ activity decreased the ratio of PGE2/PGF2α and cellular activity, while activating expression of the mTOR downstream marker-the phosphorylation of p70S6K (p-p70S6K). We also found that the PPARγ/mTOR pathway played an important role in regulating trophoblast cell function. Inhibition of the mTOR pathway by rapamycin increased the ratio of PGE2/PGF2α and decreased the expression of apoptosis-related proteins after inhibiting PPARγ activity. In conclusion, our findings provide new insights into the molecular mechanism of prostaglandin regulation of trophoblast cells in sheep during early pregnancy, indicating that the PPARγ/mTOR pathway plays an important role in PGs secretion and cell viability.

[Fkbp38 deletion induces premature ovarian insufficiency in mice by activating mTOR signaling and inducing granulosa cell apoptosis]

OBJECTIVE

To investigate the role of tacrolimus-binding protein 38 (FKBP38) in follicle development and the mechanism by which Fkbp38 gene deletion causes premature ovarian insufficiency (POI).

METHODS

The Cre-loxp system was used to construct oocyte-specific Fkbp38 knockout transgenic mice. The genotype of the transgenic mice was identified using PCR, and the expression of FKBP38 in the oocytes was verified. The numbers of primordial follicles, primary follicles, secondary follicles and antral follicles in Fkbp38 knockout mice and non-transgenic littermate control mice were counted with HE staining under a microscope for analyzing the effect of Fkbp38 deletion on follicular development. The fertility and serum sex hormone levels of the mice were determined by reproduction experiments and ELISA to assess ovarian function. Ovarian granulosa cell apoptosis of the mice was assessed using TUNEL assay. The activity of the downstream target protein of phosphorylated ribosomal S6 (PS6) of mTOR signaling pathway was detected, and the expressions of BCL-2 and BAX proteins were determined using immunofluorescence assay for assessing oocyte development in the mice.

RESULTS

The oocyte-specific Fkbp38 knockout transgenic mouse model was successfully constructed, which showed decreased fertility, disordered sex hormone levels, and significantly reduced primordial follicles, primary follicles and secondary follicles in the ovary (P < 0.05), demonstrating POI-like changes. Compared with the control mice, oocyte-specific Fkbp38 knockout caused activation of the mTOR signaling pathway, significantly increased apoptosis of the granulosa cells, and obviously increased the BAX/BCL- 2 ratio by increasing BAX expression and reducing BCL-2 expression in the oocytes (P < 0.05).

CONCLUSION

FKBP38 plays an important role in follicle development, and Fkbp38 gene deletion in mice causes POI possibly by activating the mTOR signaling pathway and inducing granulosa cell apoptosis.

Hawk Tea Flavonoids as Natural Hepatoprotective Agents Alleviate Acute Liver Damage by Reshaping the Intestinal Microbiota and Modulating the Nrf2 and NF-κB Signaling Pathways

Hawk tea (Litsea coreana Levl. var. lanuginosa) is a traditional herbal tea in southwestern China, and was found to possess hepatoprotective effects in our previous study. However, it is unclear whether hawk tea flavonoids (HTF) can alleviate alcoholic liver damage (ALD). Firstly, we extracted and identified the presence of 191 molecules categorized as HTFs, with reynoutrin, avicularin, guaijaverin, cynaroside, and kaempferol-7-O-glucoside being the most prevalent. After taking bioavailability into consideration and conducting comprehensive sorting, the contribution of guaijaverin was the highest (0.016 mg/mice). Then, by daily intragastric administration of HTF (100 mg/kg/day) to the ALD mice, we found that HTF alleviated liver lipid deposition (inhibition of TG, TC, LDL-C) by reducing liver oxidative-stress-mediated inflammation (up-regulation NRF2/HO-1 and down-regulation TLR4/MyD88/NF-κB pathway) and reshaping the gut microbiota (Lactobacillus, Bifidobacterium, Bacillus increased). Overall, we found HTF could be a potential protective natural compound for treating ALD via the gut–liver axis and guaijaverin might be the key substance involved.

The Role of Fecal Microbiota in Liver Toxicity Induced by Perfluorooctane Sulfonate in Male and Female Mice

BACKGROUND

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that can cause hepatotoxicity. The underlying toxicological mechanism remains to be investigated. Given the critical role of fecal microbiota in liver function, it is possible that fecal microbiota may contribute to the liver toxicity induced by PFOS.

OBJECTIVES

We aimed to investigate the role of liver-fecal microbiota axis in modulating PFOS-induced liver injury in mice.

METHODS

Male and female mice were exposed to PFOS or vehicle for 14 d. In this investigation, 16S rDNA sequencing and metabolomic profiling were performed to identify the perturbed fecal microbiota and altered metabolites with PFOS exposure. In addition, antibiotic treatment, fecal microbiota transplantation, and bacterial administration were conducted to validate the causal role of fecal microbiota in mediating PFOS-induced liver injury and explore the potential underlying mechanisms.

RESULTS

Both male and female mice exposed to PFOS exhibited liver inflammation and steatosis, which were accompanied by fecal microbiota dysbiosis and the disturbance of amino acid metabolism in comparison with control groups. The hepatic lesions were fecal microbiota-dependent, as supported by antibiotic treatment and fecal microbiota transplantation. Mice with altered fecal microbiota in antibiotic treatment or fecal microbiota transplantation experiments exhibited altered arginine concentrations in the liver and feces. Notably, we observed sex-specific lower levels of key microbiota, including Lactobacillus, Enterococcus, and Akkermansia. Mice treated with specific bacteria showed lower arginine levels and lower expression of the phosphorylated mTOR and P70S6K, suggesting lower activity of the related pathway and mitigation of the pathological differences observed in PFOS-exposed mice.

CONCLUSIONS

Our study demonstrated the critical role of the fecal microbiota in PFOS-induced liver injury in mice. We also identified several critical bacteria that could protect against liver injury induced by PFOS in male and female mice. Our present research provided novel insights into the mechanism of PFOS-induced liver injury in mice. https://doi.org/10.1289/EHP10281.

The Molecular Mechanism of Hepatic Lipid Metabolism Disorder Caused by NaAsO2 through Regulating the ERK/PPAR Signaling Pathway

Chronic arsenic exposure is a risk factor for human fatty liver disease, and the ERK signaling pathway plays an important role in the regulation of liver lipid metabolism. However, whether ERK plays a role in the progression of arsenic-induced liver lipid metabolism disorder and the specific mechanism remain unclear. Here, by constructing a rat model of liver lipid metabolism disorder induced by chronic arsenic exposure, we demonstrated that ERK might regulate arsenic-induced liver lipid metabolism disorders through the PPAR signaling pathway. Arsenic could upregulate the expression of PPARγ and CD36 in the rat liver, decrease the expression of PPARα and CPT-1 in the rat liver, increase the organ coefficient of the rat liver, decrease the content of TG in rat serum, and promote fat deposition in the rat liver. In the arsenic-induced rat model of hepatic lipid metabolism disorder, we found that the expression of p-ERK was increased. In order to further explore whether the ERK signaling pathway was involved in arsenic-induced liver lipid metabolism disorder, we exposed L-02 cells to different arsenic concentrations, and the results showed that arsenic significantly increased the expression of P-ERK in L-02 cells in a dose-dependent manner. We further treated L-02 cells with ERK inhibitors and found that the expression of TG, PPARα, and CPT-1 in L-02 cells increased, while the expression of P-ERK, PPARγ, and CD36 decreased. In conclusion, ERK may be involved in arsenic-induced liver lipid metabolism disorder by regulating the PPAR signaling pathway. These findings are expected to provide a new targeting strategy for arsenic-induced liver lipid metabolism disorder.

Comprehensive multi-omics approaches reveal the hepatotoxic mechanism of perfluorohexanoic acid (PFHxA) in mice

Perfluorohexanoic acid (PFHxA), one of the short-chain perfluoroalkyl acids (PFAAs), is considered as a substitute of perfluorooctane sulfonate (PFOS). This emerging organic pollutant is persistent and highly bioavailable to humans, raising concerns about its potential health risks. There are currently few researches on the toxicity of PFHxA. Liver has been suggested to be the main target of PFHxA toxicity, and the mechanism remains unclear. Herein, we investigated the transcriptomic, proteomic, and metabolomic landscape in PFHxA-exposed mice. Using these approaches, we identified several valuable biological processes involved in the process of liver injury, comprising fatty acid biosynthesis and degradation pathways, which might be induced by peroxisome proliferator-activated receptor (PPAR) signaling pathway. These processes further promoted oxidative stress and induced liver injury. Meanwhile, abnormalities in purine metabolism and glutathione metabolism were observed during the liver injury induced by PFHxA, indicating the production of oxidative stress. Finally, our present multi-omics studies provided new insights into the mechanisms involved in PFHxA-induced liver injury.