Mitogen-Activated Protein Kinase Regulation in Hepatic Metabolism

Epigallocatechin gallate improves oleic acid-induced hepatic steatosis in laying hen hepatocytes via the MAPK pathway

Fatty liver disease in laying hens, characterized by excessive lipid accumulation in hepatocytes, poses significant challenges to poultry health and production efficiency. In this study, we investigated the therapeutic potential of epigallocatechin gallate (EGCG), a bioactive compound found in green tea, in mitigating oleic acid (OA)-induced hepatic steatosis in primary chicken hepatocytes. Treatment with EGCG effectively attenuated lipid deposition by downregulating lipid synthesis-related genes. Moreover, EGCG mitigated oxidative stress, inflammation, DNA damage, and apoptosis induced by OA, thereby preserving hepatocyte viability. Mechanistically, EGCG exerted its protective effects by modulating the p38 MAPK signaling pathway. Our findings suggest that EGCG holds promise as a therapeutic agent for managing fatty liver disease in poultry, offering insights into novel strategies for improving poultry health and production outcomes.

Modulation of glycolipid metabolism in T2DM rats by Rubus irritans Focke extract: Insights from metabolic profiling and ERK/IRS-1 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The extracellular regulated protein kinase (ERK) plays a crucial role in the mitogen-activated protein kinase (MAPK) family, influencing apoptosis, proliferation, and differentiation. It connection to the insulin (INS) signaling cascade and the development of type 2 diabetes mellitus (T2DM) has been established. Rubus irritans Focke, an indispensable herb in Chinese Tibetan medicine for diabetes mellitus treatment, lacks a comprehensive understanding of its effects and pharmacological mechanisms in T2DM.

AIM OF THE STUDY

This study aimed to elucidate the effects of Rubus irritans Focke extract (Rife) on a T2DM rat model, exploring its impact on glycemic and lipid metabolism, histopathological changes, and its potential targeting of the extracellular regulated protein kinase/insulin receptor substrate-1 (ERK/IRS-1) signaling pathway.

MATERIALS AND METHODS

A T2DM rat model was induced by streptozotocin (STZ) injection (40 mg/kg) in high-fat diet-fed (HFD) male Wistar rats. Rife and metformin (Met) were administered for 4 weeks, and glycemic, lipid metabolism indices, and histopathological changes were assessed. Protein expression of ERK, IRS-1 in rat liver tissues was examined to evaluate the impact on the ERK/IRS-1 pathway.

RESULTS

Rife reducing hepatic ERK and IRS-1 protein expression in T2DM rats. Untargeted metabolomics identified 13 potential biomarkers and 4 differential metabolic pathways related to glycolipid metabolism disorders.

CONCLUSIONS

Rife demonstrated improved glycolipid metabolism in T2DM rats by inhibiting the ERK/IRS-1 related signaling pathway and influencing multiple metabolic pathways. This study provides valuable insights into the potential therapeutic mechanisms of Rife in the context of T2DM.

Hepatocyte-Specific Casein Kinase 1 Epsilon Ablation Ameliorates Metabolic Dysfunction-Associated Steatohepatitis by Up-Regulating Tumor Necrosis Factor Receptor-Associated Factor 3 in Mice

Casein kinase 1 epsilon (CK1ε), a member of the serine/threonine protein kinase family, is known to phosphorylate a broad range of substrates. However, its role in the development of chronic liver diseases remains elusive. This study aimed to investigate the role of CK1ε in the development and progression of metabolic dysfunction-associated steatohepatitis (MASH). Hepatocyte-specific CK1ε knockout (CK1εΔHEP) mice were generated by crossbreeding mice with floxed CK1ε alleles (CK1εfl/fl) and Cre-expressing albumin mice. Mice were fed either a Western diet (WD) or a methionine- and choline-deficient diet to induce MASH. CK1εΔHEP was associated with a decreased severity of WD- or methionine- and choline-deficient diet-induced MASH, as confirmed by reduced incidence of hepatic lesions and significantly lower levels of alanine aminotransferase, aspartate aminotransferase, and proinflammatory cytokine tumor necrosis factor (TNF)-α. CK1εΔHEP WD-fed mice exhibited significant amelioration of total cholesterol, triglycerides, and de novo lipogenic genes, indicating that CK1ε could influence lipid metabolism. CK1εΔHEP WD-fed mice showed significantly down-regulated TNF receptor-associated factor 3, phosphorylated (p) transforming growth factor-β-activated kinase 1, p-TANK-binding kinase 1, and p-AKT levels, thereby affecting downstream mitogen-activated protein kinase signaling, indicating a potential mechanism for the observed rescue. Finally, pharmacologic inhibition of CK1ε with PF670462 improved palmitic acid-induced steatohepatitis in vitro and attenuated WD-induced metabolic profile in vivo. In conclusion, CK1ε up-regulates TNF receptor-associated factor 3, which, in turn, causes transforming growth factor-β-activated kinase 1-dependent signaling, amplifies downstream mitogen-activated protein kinase signaling, modifies p-c-Jun levels, and exacerbates inflammation, all of which are factors in WD-induced metabolic dysfunction-associated steatotic liver disease.

Treatment with 1.25% cholesterol enriched diet produces severe fatty liver disease characterized by advanced fibrosis and inflammation and impaired autophagy in mice

Nonalcoholic fatty liver disease (NAFLD) is reaching pandemic proportions due to overnutrition. The understanding of advanced stages that recapitulate the human pathology is of great importance to get a better mechanistic insight. We hypothesized that feeding of WT (C57BL) mice with a diet containing a high content of fat (21%), sugar (41.5%) and 1.25% of cholesterol (called from now on high fat, sucrose and cholesterol diet, HFSCD) will reproduce the characteristics of disease severity. Analysis of 16 weeks HFSCD-fed mice demonstrated increased liver weight and plasmatic liver damage markers compared with control diet (CD)-fed mice. HFSCD-fed mice developed greater hepatic triglyceride, cholesterol and NEFA content, inflammation and NAFLD activity score (NAS) indicating an advanced disease. HFSCD-fed mice displayed augmented hepatic total CD3+ T and Th9 lymphocytes, as well as reduced Th2 lymphocytes and CD206 anti-inflammatory macrophages. Moreover, T cells and anti-inflammatory macrophages correlated positively and inversely, respectively, with intrahepatic cholesterol content. Consistently, circulating cytotoxic CD8+ T lymphocytes, Th1, and B cell levels were elevated in HFSCD-fed WT mice. Hepatic and adipose tissue expression analysis demonstrated changes in fibrotic and metabolic genes related with cholesterol, triglycerides, and fatty acid synthesis in HFSCD-fed WT. These mice also exhibited reduced antioxidant capacity and autophagy and elevated ERK signaling pathway activation and CHOP levels. Our results indicate that the feeding with a cholesterol-enriched diet in WT mice produces an advanced NAFLD stage with fibrosis, characterized by deficient autophagy and ER stress along with inflammasome activation partially via ERK pathway activation.

Gut mycobiome alterations and implications for liver diseases

Chronic liver disease and its complications are a significant global health burden. Changes in fungal communities (mycobiome), an integral component of the gut microbiome, are associated with and contribute to the development of liver disease. Fungal dysbiosis can induce intestinal barrier dysfunction and allow fungal products to translocate to the liver causing progression of disease. This review explores recent progress in understanding the compositional and functional diversity of gut mycobiome signatures across different liver diseases. It delves into causative connections between gut fungi and liver diseases. We emphasize the significance of fungal translocation, with a particular focus on fungal-derived metabolites and immune cells induced by fungi, as key contributors to liver disease. Furthermore, we review the potential impact of the intrahepatic mycobiome on the progression of liver diseases.

The PI3K/Akt signaling axis and type 2 diabetes mellitus (T2DM): From mechanistic insights into possible therapeutic targets

Type 2 diabetes mellitus (T2DM) is an immensely debilitating chronic disease that progressively undermines the well-being of various bodily organs and, indeed, most patients succumb to the disease due to post-T2DM complications. Although there is evidence supporting the activation of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway by insulin, which is essential in regulating glucose metabolism and insulin resistance, the significance of this pathway in T2DM has only been explored in a few studies. The current review aims to unravel the mechanisms by which different classes of PI3Ks control the metabolism of glucose; and also to discuss the original data obtained from international research laboratories on this topic. We also summarized the role of the PI3K/Akt signaling axis in target tissues spanning from the skeletal muscle to the adipose tissue and liver. Furthermore, inquiries regarding the impact of disrupting this axis on insulin function and the development of insulin resistance have been addressed. We also provide a general overview of the association of impaired PI3K/Akt signaling pathways in the pathogenesis of the most prevalent diabetes-related complications. The last section provides a special focus on the therapeutic potential of this axis by outlining the latest advances in active compounds that alleviate diabetes via modulation of the PI3K/Akt pathway. Finally, we comment on the future research aspects in which the field of T2DM therapies using PI3K modulators might be developed.

Macrophage-specific FGFR1 deletion alleviates high-fat-diet-induced liver inflammation by inhibiting the MAPKs/TNF pathways

Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disease that is substantially associated with obesity-induced chronic inflammation. Macrophage activation and macrophage-medicated inflammation play crucial roles in the development and progression of NAFLD. Furthermore, fibroblast growth factor receptor 1 (FGFR1) has been shown to be essentially involved in macrophage activation. This study investigated the role of FGFR1 in the NAFLD pathogenesis and indicated that a high-fat diet (HFD) increased p-FGFR1 levels in the mouse liver, which is associated with increased macrophage infiltration. In addition, macrophage-specific FGFR1 knockout or administration of FGFR1 inhibitor markedly protected the liver from HFD-induced lipid accumulation, fibrosis, and inflammatory responses. The mechanistic study showed that macrophage-specific FGFR1 knockout alleviated HFD-induced liver inflammation by suppressing the activation of MAPKs and TNF signaling pathways and reduced fat deposition in hepatocytes, thereby inhibiting the activation of hepatic stellate cells. In conclusion, the results of this research revealed that FGFR1 could protect the liver of HFD-fed mice by inhibiting MAPKs/TNF-mediated inflammatory responses in macrophages. Therefore, FGFR1 can be employed as a target to prevent the development and progression of NAFLD.

Recent advances in toxicological research of di-(2-ethylhexyl)-phthalate: Focus on endoplasmic reticulum stress pathway

The plasticizer di-(2-ethylhexyl)-phthalate (DEHP) is the most significant phthalate in production, usage, and environmental occurrence. DEHP is found in products such as personal care products, furniture materials, cosmetics, and medical devices. DEHP is noncovalently bind with plastic therefore, repeated uses lead to leaching out of it. Exposure to DEHP plasticizers leads to toxicity in essential organs of the body through various mechanisms. The main objective of this review article is to focus on the DEHP-induced endoplasmic reticulum (ER) stress pathway implicated in the testis, brain, lungs, kidney, heart, liver, and other organs. Not only ER stress, PPAR-related pathways, oxidative stress and inflammation, Ca2+ homeostasis disturbances in mitochondria are also identified as the relative mechanisms. ER is involved in various critical functions of the cell such as Protein synthesis, protein folding, calcium homeostasis, and lipid peroxidation but, DEHP exposure leads to augmentation of misfolded/unfolded protein. This review complies with various recently reported DEHP-induced toxicity studies and some pharmacological interventions that have been shown to be effective through ER stress pathway. DEHP exposure does assess health risks and vulnerability to populations across the globe. This study offers possible targets and approaches for addressing various DEHP-induced toxicity.

Effect of Calebin-A on Critical Genes Related to NAFLD: A Protein-Protein Interaction Network and Molecular Docking Study

Background

Calebin-A is a minor phytoconstituent of turmeric known for its activity against inflammation, oxidative stress, cancerous, and metabolic disorders like Non-alcoholic fatty liver disease(NAFLD). Based on bioinformatic tools. Subsequently, the details of the interaction of critical proteins with Calebin-A were investigated using the molecular docking technique.

Methods

We first probed the intersection of genes/ proteins between NAFLD and Calebin-A through online databases. Besides, we performed an enrichment analysis using the ClueGO plugin to investigate signaling pathways and gene ontology. Next, we evaluate the possible interaction of Calebin-A with significant hub proteins involved in NAFLD through a molecular docking study.

Results

We identified 87 intersection genes Calebin-A targets associated with NAFLD. PPI network analysis introduced 10 hub genes (TP53, TNF, STAT3, HSP90AA1, PTGS2, HDAC6, ABCB1, CCT2, NR1I2, and GUSB). In KEGG enrichment, most were associated with Sphingolipid, vascular endothelial growth factor A (VEGFA), C-type lectin receptor, and mitogen-activated protein kinase (MAPK) signaling pathways. The biological processes described in 87 intersection genes are mostly concerned with regulating the apoptotic process, cytokine production, and intracellular signal transduction. Molecular docking results also directed that Calebin-A had a high affinity to bind hub proteins linked to NAFLD.

Conclusion

Here, we showed that Calebin-A, through its effect on several critical genes/ proteins and pathways, might repress the progression of NAFLD.

Glycyrrhizic acid restores the downregulated hepatic ACE2 signaling in the attenuation of mouse steatohepatitis

Glycyrrhizic acid (GA), one of the major active components derived from licorice root, exerts liver-protecting activity. Its molecular mechanisms of action, however, remain not completely understood. The angiotensin (Ang) converting enzyme (ACE) 2/Ang-(1-7)/Mas axis, regulated by ACE2 through converting Ang II into Ang-(1-7) to activate Mas receptor, counteracts the pro-inflammatory and pro-steatotic effects of the ACE/Ang II/Ang II receptor type 1 (AT1) axis. Here, it was found that pretreatment with GA suppressed LPS/D-galactosamine-induced serum hyperactivities of alanine aminotransferase and aspartate aminotransferase, hepatomegaly, pathological changes, and over-accumulation of triglycerides and fatty droplets in the liver of mice. GA also diminished LPS/free fatty acid-induced inflammation and steatosis in cultured hepatocytes. Mechanistically, GA restored hepatic protein hypoexpression of ACE2 and Mas receptor, and the decrease in hepatic Ang-(1-7) content. Hepatic overexpression of angiotensin II and AT1 was also suppressed. However, GA did not alter hepatic protein expression of renin and ACE. In addition, GA inhibited hepatic protein over-phosphorylation of the p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, extracellular signal-regulated kinase, and nuclear factor κB at Ser536. Hepatic overexpression of tumor necrosis factor α, interleukin 6, interleukin 1β, sterol regulatory element-binding protein 1c, and fatty acid synthase was also inhibited. GA-elicited recovery of ACE2 and Mas protein hypoexpression was further confirmed in the hepatocyte. Thus, the present results demonstrate that GA restores the downregulated hepatic ACE2-mediated anti-inflammatory and anti-steatotic signaling in the amelioration of steatohepatitis. We suggest that GA may protect the liver from injury by regulating the hepatic ACE2-mediated signaling.

The micro-743a-3p-GSTM1 pathway is an endogenous protective mechanism against alcohol-related liver disease in mice

BACKGROUND AND AIMS

Epidemiological evidence suggests that the phenotype of glutathione S-transferase mu 1 (GSTM1), a hepatic high-expressed phase II detoxification enzyme, is closely associated with the incidence of alcohol-related liver disease (ALD). However, whether and how hepatic GSTM1 determines the development of ALD is largely unclear. This study was designed to elucidate the role and potential mechanism(s) of hepatic GSTM1 in the pathological process of ALD.

METHODS

GSTM1 was detected in the liver of various ALD mice models and cultured hepatocytes. Liver-specific GSTM1 or/and micro (miR)-743a-3p deficiency mice were generated by adenoassociated virus-8 delivered shRNA, respectively. The potential signal pathways involving in alcohol-regulated GSTM1 and GSTM1-associated ALD were explored via both genetic manipulation and pharmacological approaches.

RESULTS

GSTM1 was significantly upregulated in both chronic alcohol-induced mice liver and ethanol-exposed murine primary hepatocytes. Alcohol-reduced miR-743a-3p directly contributed to the upregulation of GSTM1, since liver specific silencing miR-743a-3p enhanced GSTM1 and miR-743a-3p loss protected alcohol-induced liver dysfunctions, which was significantly blocked by GSTM1 knockdown. GSTM1 loss robustly aggravated alcohol-induced hepatic steatosis, oxidative stress, inflammation, and early fibrotic-like changes, which was associated with the activation of apoptosis signal-regulating kinase 1 (ASK1), c-Jun N-terminal kinase (JNK), and p38. GSTM1 antagonized ASK1 phosphorylation and its downstream JNK/p38 signaling pathway upon chronic alcohol consumption via binding with ASK1. ASK1 blockage significantly rescued hepatic GSTM1 loss-enhanced disorders in alcohol-fed mice liver.

CONCLUSIONS

Chronic alcohol consumption-induced upregulation of GSTM1 in the liver provides a feedback protection against hepatic steatosis and liver injury by counteracting ASK1 activation. Down-regulation of miR-743a-3p improves alcohol intake-induced hepatic steatosis and liver injury via direct targeting on GSTM1. The miR-743a-3p-GSTM1 axis functions as an innate protective pathway to defend the early stage of ALD.

Polystyrene nanoplastics induce glycolipid metabolism disorder via NF-κB and MAPK signaling pathway in mice

Nanoplastics-induced developmental and reproductive toxicity, neurotoxicity and immunotoxicity are a focus of widespread attention. However, the effects of nanoplastics (NPs) on glycolipid metabolism and the precise underlying mechanisms are unclear at present. Here, we showed that oral administration of polystyrene nanoparticles (PS-NPs) disrupts glycolipid metabolism, with reactive oxygen species (ROS) identified as a potential key signaling molecule. After PS-NPs treatment, excessive production of ROS induced the inflammatory response and activated the antioxidant pathway through nuclear factor-erythroid factor 2-related factor 2. The activation of nuclear factor-κB (NFκB) signaling pathway induced the phosphorylation of the mitogen-activated protein kinases (MAPK) signaling pathway, which induced the activation of extracellular regulated kinases (ERK) and p38. Constitutive activation of the MAPK signaling proteins induced high continued phosphorylation of insulin receptor substrate-1, in turn, leading to decreased protein kinase B (Akt) activity, which weakened the sensitivity of liver cells to insulin signals and induced insulin resistance. In parallel, phosphorylation of Akt led to loss of control of FoXO1, a key gene of gluconeogenesis, activating transcription of glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase (PEPCK) in a manner dependent on PGC1α. Moreover, the activated ERK promoted lipid accumulation through ERK-PPARγ cascades. Therefore, sterol regulatory element-binding protein-1 and levels of its downstream lipogenic enzymes, ACC-1, were up-regulated. Upon treatment with the antioxidant resveratrol, PS-NPs-induced glucose and lipid metabolic disorders were improved by inhibiting ROS-induced activation of NFκB and MAPK signaling pathway in mice. Based on above, PS-NPs exposure disrupts glycolipid metabolism in mice, with ROS identified as a potential key signaling molecule.

Bulbils of Aerial Yam Attenuate Ethanol-Induced Hepatotoxicity in HepG2 Cells through Inhibition of Oxidative Stress by Activation of the Nuclear Factor Erythroid-2-Related Factor 2 Signaling Pathway

Bulbil of yam (BY) extract contains various active compounds possessing many pharmacological properties. However, little is known about the effect and underlying mechanism of BY extract on ethanol-induced liver damage. The present study explored the beneficial potential of BY extract on ethanol-induced hepatotoxicity. To evaluate its effectiveness, ethanol-induced HepG2 liver cells were pretreated with BY extract. BY extract effectively rescued cells from ethanol treatment through inhibition of apoptotic cell death as well as inhibiting expression of mitogen-activated protein kinase (MAPK) proteins as stress inducers. BY extract increased the expression of typical antioxidants. Furthermore, BY extract significantly inhibited mitochondrial dysfunction and endoplasmic reticulum (ER) stress, which are major ROS-inducing factors. Finally, as an underlying mechanism of the protective effects of BY extract on ethanol-induced liver damage, it activated Nrf2 protein through translocation from the cytosol to the nucleus, which in turn activated its target oxidative stress suppressor genes. Collectively, our findings demonstrate that BY extract has potential antioxidative effects in ethanol-induced liver cells and contributes to the establishment of a treatment strategy for alcohol-derived liver injuries.

Molecular mechanism of microRNA-mediated hypoglycemic effect of whole grain highland barley

As a non-coding RNA, microRNA (miRNA) has been proven to play an important role in the development and progression of type 2 diabetes mellitus (T2DM). Highland barley is a whole grain from the Tibetan areas of China. Our previous studies have demonstrated its hypoglycemic effect. To further explore the underlining molecular mechanism, we investigated the effect of highland barley intervention on liver miRNA expression profiles in diabetic mice. Our results showed that ten differentially expressed miRNA among different groups were identified and their target genes were predicted. Remarkably, many glycometabolism-associated genes, including Foxo3, Nras, Rptor, Igf1r, Tsc2 and Braf, were negatively regulated by miR-122-5p, miR-503-5p, miR-455-5p and miR-210-3p, respectively. Pathway enrichment analysis revealed these target genes were mainly involved in AMPK, MAPK and FOXO signaling pathways. Thereby, these miRNA and mRNA were validated using qRT-PCR, and the results were consistent with the small RNA-seq and expectations. Highland barley could regulate the MAPK, AMPK, and FOXO signaling pathways by regulating critical miRNA-mRNA pairs, e.x. miR-210-3p-Tsc2/Braf, miR-122-5p-Foxo3, and miR-455-5p-Igf1r, thereby improving blood glucose metabolism in diabetic mice. The present study preliminarily explored the hypoglycaemic effects of highland barley based on transcriptomics, and more detailed and in-depth studies on this topic are needed in the future.

Multispecies transcriptomics identifies SIKE as a MAPK repressor that prevents NASH progression

Nonalcoholic fatty liver (NAFL) remains relatively benign, but high-risk to end-stage liver diseases become highly prevalent when it progresses into nonalcoholic steatohepatitis (NASH). Our current understanding of the development of NAFL to NASH remains insufficient. In this study, we revealed MAP kinase (MAPK) activation as the most notable molecular signature associated with NASH progression across multiple species. Furthermore, we identified suppressor of IKKε (SIKE) as a conserved and potent negative controller of MAPK activation. Hepatocyte-specific overexpression of Sike prevented NASH progression in diet- and toxin-induced mouse NASH models. Mechanistically, SIKE directly interacted with TGF-β-activated kinase 1 (TAK1) and TAK1-binding protein 2 (TAB2) to interrupt their binding and subsequent TAK1-MAPK signaling activation. We found that indobufen markedly up-regulated SIKE expression and effectively improved NASH features in mice and macaques. These findings identify SIKE as a MAPK suppressor that prevents NASH progression and provide proof-of-concept evidence for targeting the SIKE-TAK1 axis as a potential NASH therapy.

Tea seed saponin‑reduced extract ameliorates palmitic acid‑induced insulin resistance in HepG2 cells

Tea (Camellia sinensis) seed cake is a potential resource that contains a wealth of bioactive compounds. However, the high toxicity of tea saponins in tea seed cake restricts its applications. The present study aimed to i) develop a method of extracting bioactive compounds and reducing tea saponins during the process of tea seed cake extraction and ii) investigate the anti‑insulin resistance effect of tea seed saponin‑reduced extract (TSSRE) in a palmitic acid (PA)‑induced insulin resistance HepG2‑cell model. The concentration of tea saponins in TSSRE was ~10‑fold lower than that in tea seed crude extract (TSCE) after the saponin‑reduction process. In addition, TSSRE cytotoxicity was significantly lower than that of TSCE in HepG2 cells. TSSRE treatment improved glucose consumption as well as glucose transporter (GLUT) 2 and GLUT4 expression levels in PA‑stimulated HepG2 cells. Moreover, TSSRE enhanced the phosphorylation of the insulin receptor substrate 1/protein kinase B/forkhead box protein O1/glycogen synthase kinase 3β and inhibited the elevated expression of phosphoenolpyruvate carboxykinase in PA‑exposed HepG2 cells. The effect of TSSRE on the mediation of the insulin signaling pathway was attributed to the inhibition of PA‑induced mitogen‑activated protein kinase activation. The findings of the present study indicated that TSSRE ameliorates hepatic insulin resistance by ameliorating insulin signaling and inhibiting inflammation-related pathways.

LncRNA H19 inhibition impairs endoplasmic reticulum-mitochondria contact in hepatic cells and augments gluconeogenesis by increasing VDAC1 levels

Inspite of exerting independent cellular functions, the endoplasmic-reticulum (ER) and the mitochondria also physically connect at specific sites termed mitochondria-associated ER membranes (MAMs) and these sites consist of several tethering proteins that play varied roles in diverse cellular processes. However, the regulation of these tethering proteins within the cell is relatively less studied. Here, we show that several MAM proteins are significantly altered in the liver during diabetes and among these, the lncRNA, H19 regulates the levels of VDAC1. Inhibition of H19 expression using H19 specific siRNA altered VDAC1, mitochondrial Ca2+ and oxygen consumption rate, ATP and ROS levels and enhanced ER and mitochondria coupling in Hepa 1-6 cells. While H19 inhibition did not impact lipid accumulation, levels of gluconeogenic genes were significantly increased. JNK-phosphorylation and IRS1-Ser307-phosphorylation were increased by H19 inhibition and this was associated with abrogation of insulin-stimulated AKT (Ser-473) phosphorylation and glucose uptake in Hepa 1-6 cells. While inhibition of VDAC1 expression using siRNAs and with metformin significantly rescued the effects of H19 inhibition, VDAC1 overexpression alone exerted effects similar to H19 inhibition, suggesting that VDAC1 increase mediates the adverse effects of H19. In-vivo H19 inhibition using specific siRNAs increased hepatic VDAC1, pJNK and pIRS1 (Ser307) levels and decreased AKT (Ser-473) phosphorylation in mice. These suggest an important role of the H19-VDAC1 axis in ER-mitochondria coupling and regulation of gluconeogenesis in the liver during diabetes.

Prepared Radix Polygoni Multiflori and emodin alleviate lipid droplet accumulation in nonalcoholic fatty liver disease through MAPK signaling pathway inhibition

As one of the most common liver diseases, nonalcoholic fatty liver disease (NAFLD) affects almost one-quarter of the world's population. Although the prevalence of NAFLD is continuously rising, effective medical treatments are still inadequate. Radix Polygoni Multiflori (RPM) is a traditional Chinese herbal medicine. As a processed product of RPM, prepared Radix Polygoni Multiflori (PRPM) has been reported to have antioxidant and anti-inflammatory effects. This study investigated whether PRPM treatment could significantly improve NAFLD. We used recent literature, the Herb database and the SwissADME database to isolate the active compounds of PRPM. The OMIM, DisGeNET and GeneCards databases were used to isolate NAFLD-related target genes, and GO functional enrichment and KEGG pathway enrichment analyses were conducted. Moreover, PRPM treatment in NAFLD model mice was evaluated. The results indicate that the target genes are mainly enriched in the AMPK and de novo lipogenesis signaling pathways and that PRPM treatment improves NAFLD disease in model mice. Here, we found the potential benefits of PRPM against NAFLD and demonstrated in vivo and in vitro that PRPM and its ingredient emodin downregulate phosphorylated P38/P38, phosphorylated ERK1/2 and genes related to de novo adipogenesis signaling pathways and reduce lipid droplet accumulation. In conclusion, our findings revealed a novel therapeutic role for PRPM in the treatment of NAFLD and metabolic inflammation.

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

Excessive expansion of adipocytes can have unhealthy consequences as excess free fatty acids enter other tissues and cause ectopic fat deposition by resynthesizing triglycerides. This lipid accumulation in various tissues is harmful and can increase the risk of related metabolic diseases such as type II diabetes, cardiovascular disease, and insulin resistance. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that play a key role in energy metabolism as fatty acid metabolism sensors, and peroxisome proliferator-activated receptor γ (PPARγ) is the main subtype responsible for fat cell differentiation and adipogenesis. In this paper, we introduce the main structure and function of PPARγ and its regulatory role in the process of lipogenesis in the liver, kidney, skeletal muscle, and pancreas. This information can serve as a reference for further understanding the regulatory mechanisms and measures of the PPAR family in the process of ectopic fat deposition.

Molecular Targets and Mechanisms of Casein-Derived Tripeptides Ile-Pro-Pro and Val-Pro-Pro on Hepatic Glucose Metabolism

The objective of this study was to explore the molecular targets and mechanism of Ile-Pro-Pro (IPP) and Val-Pro-Pro (VPP) on regulating glucose metabolism in hepatic cells and their in vivo hypoglycemic activities in mice. Results showed that both IPP and VPP (600 μM) significantly enhanced the glucose consumption in HepG2 cells and primary hepatocytes (p < 0.05). They also regulated activities of glucose metabolizing enzymes and increased the protein expression of p-AKT and GLUT2 in HepG2 cells. IPP directly interacted with the insulin receptor (IR) to activate the insulin/AKT signaling pathway. The activity of VPP on glucose consumption was not attributed to IR binding, and 76 potential antidiabetic targets were predicted by similarity ensemble and shape similarity approaches. Among them, the AKT and MAPK signaling pathway, in which two hub genes AKT1 and MAPK4 existed, were evaluated to make major contributions to the activity of VPP on glucose consumption. Moreover, both IPP and VPP (300 μmol/kg) could significantly reduce the blood glucose levels in mice (p < 0.05), with blood glucose area under the curve dropping by approximately 19% ± 0.09 and 21% ± 0.11%, respectively. This study provides a new theoretical support for the development of IPP and VPP as functional foods to regulate glucose metabolic disorders.

Maternal-Periconceptional Vitamin B12 Deficiency in Wistar Rats Leads to Sex-Specific Programming for Cardiometabolic Disease Risk in the Next Generation

BACKGROUND

Maternal vitamin B12 deficiency plays a vital role in fetal programming, as corroborated by previous studies on murine models and longitudinal human cohorts.

OBJECTIVES

This study assessed the effects of diet-induced maternal vitamin B12 deficiency on F1 offspring in terms of cardiometabolic health and normalization of these effects by maternal-periconceptional vitamin B12 supplementation.

METHODS

A diet-induced maternal vitamin B12 deficient Wistar rat model was generated in which female rats were either fed a control AIN-76A diet (with 0.01 g/kg vitamin B12) or the same diet with vitamin B12 removed. Females from the vitamin B12-deficient group were mated with males on the control diet. A subset of vitamin B12-deficient females was repleted with vitamin B12 on day 1 of conception. The offspring in the F1 generation were assessed for changes in body composition, plasma biochemistry, and molecular changes in the liver. A multiomics approach was used to obtain a mechanistic insight into the changes in the offspring liver.

RESULTS

We showed that a 36% reduction in plasma vitamin B12 levels during pregnancy in F0 females can lead to continued vitamin B12 deficiency (60%-70% compared with control) in the F1 offspring and program them for cardiometabolic adversities. These adversities, such as high triglycerides and low high-density lipoprotein cholesterol, were seen only among F1 males but not females. DNA methylome analysis of the liver of F1 3-mo-old offspring highlights sexual dimorphism in the alteration of methylation status of genes critical to signaling processes. Proteomics and targeted metabolomics analysis confirm that sex-specific alterations occur through modulations in PPAR signaling and steroid hormone biosynthesis pathway. Repletion of deficient mothers with vitamin B12 at conception normalizes most of the molecular and biochemical changes.

CONCLUSIONS

Maternal vitamin B12 deficiency has a programming effect on the next generation and increases the risk for cardiometabolic syndrome in a sex-specific manner. Normalization of the molecular risk markers on vitamin B12 supplementation indicates a causal role.

Konjac glucomannan attenuate high-fat diet-fed obesity through enhancing β-adrenergic-mediated thermogenesis in inguinal white adipose tissue in mice

Konjac glucomannan (KGM) has been reported to prevent high-fat diet-induced obesity, and we study investigated whether dietary supplementation with KGM can prevent obesity by increasing energy expenditure in inguinal white adipose tissue (iWAT) of high-fat diet (HF) -fed mice. Weaned mice fed the control diet (Con), HF, or HF plus KGM (8%, w/w, HFK) were divided into three groups. The results showed that 10-week supplementation with KGM significantly reduced partial adipose tissue weight and body weight, and improved glucose tolerance. Compared to the HF group, plasma lipid concentrations in the HFK group were greatly decreased to the control level. Moreover, transcriptomic research has shown that genes that are mainly associated with energy and lipid metabolism are significantly altered in iWAT. Mechanistically, KGM stimulated thermogenesis by promoting the expression of uncoupling protein-1 (UCP1) and the β3-adrenergic receptor (ADR3β). Taken together, our results suggest that dietary supplementation with konjac glucomannan can effectively alleviate obesity induced by a high-fat diet by activating ADR3β-mediated iWAT thermogenesis. Dietary supplementation with KGM can effectively alleviate high fat diet- induced obesity mice by via activating ADR3β-mediated thermogenesis of iWAT.

MKP1 promotes nonalcoholic steatohepatitis by suppressing AMPK activity through LKB1 nuclear retention

Nonalcoholic steatohepatitis (NASH) is triggered by hepatocyte death through activation of caspase 6, as a result of decreased adenosine monophosphate (AMP)-activated protein kinase-alpha (AMPKα) activity. Increased hepatocellular death promotes inflammation which drives hepatic fibrosis. We show that the nuclear-localized mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP1) is upregulated in NASH patients and in NASH diet fed male mice. The focus of this work is to investigate whether and how MKP1 is involved in the development of NASH. Under NASH conditions increased oxidative stress, induces MKP1 expression leading to nuclear p38 MAPK dephosphorylation and decreases liver kinase B1 (LKB1) phosphorylation at a site required to promote LKB1 nuclear exit. Hepatic deletion of MKP1 in NASH diet fed male mice releases nuclear LKB1 into the cytoplasm to activate AMPKα and prevents hepatocellular death, inflammation and NASH. Hence, nuclear-localized MKP1-p38 MAPK-LKB1 signaling is required to suppress AMPKα which triggers hepatocyte death and the development of NASH.

MKP1 promotes nonalcoholic steatohepatitis by suppressing AMPK activity through LKB1 nuclear retention

Nonalcoholic steatohepatitis (NASH) is triggered by hepatocyte death through activation of caspase 6, as a result of decreased adenosine monophosphate (AMP)-activated protein kinase-alpha (AMPKα) activity. Increased hepatocellular death promotes inflammation which drives hepatic fibrosis. We show that the nuclear-localized mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP1) is upregulated in NASH patients and in NASH diet fed mice. The focus of this work was to investigate whether and how MKP1 is involved in the development of NASH. Under NASH conditions increased oxidative stress, induces MKP1 expression leading to nuclear p38 MAPK dephosphorylation and decreased liver kinase B1 (LKB1) phosphorylation at a site required to promote LKB1 nuclear exit. Hepatic deletion of MKP1 in NASH diet fed mice released nuclear LKB1 into the cytoplasm to activate AMPKα and prevent hepatocellular death, inflammation and NASH. Hence, nuclear-localized MKP1-p38 MAPK-LKB1 signaling is required to suppress AMPKα which triggers hepatocyte death and the development of NASH.

Obesity, non-alcoholic fatty liver disease and hepatocellular carcinoma: current status and therapeutic targets

Obesity is a global epidemic and overwhelming evidence indicates that it is a risk factor for numerous cancers, including hepatocellular carcinoma (HCC), the third leading cause of cancer-related deaths worldwide. Obesity-associated hepatic tumorigenesis develops from nonalcoholic fatty liver disease (NAFLD), progressing to nonalcoholic steatohepatitis (NASH), cirrhosis and ultimately to HCC. The rising incidence of obesity is resulting in an increased prevalence of NAFLD and NASH, and subsequently HCC. Obesity represents an increasingly important underlying etiology of HCC, in particular as the other leading causes of HCC such as hepatitis infection, are declining due to effective treatments and vaccines. In this review, we provide a comprehensive overview of the molecular mechanisms and cellular signaling pathways involved in the pathogenesis of obesity-associated HCC. We summarize the preclinical experimental animal models available to study the features of NAFLD/NASH/HCC, and the non-invasive methods to diagnose NAFLD, NASH and early-stage HCC. Finally, since HCC is an aggressive tumor with a 5-year survival of less than 20%, we will also discuss novel therapeutic targets for obesity-associated HCC and ongoing clinical trials.

Signaling pathways and intervention for therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.

Bombax ceiba Linn. leaf extract rich in phenolic compounds to mitigate non-alcoholic fatty liver-related complications in experimental model

OBJECTIVES

Obesity, diabetes mellitus, insulin resistance (IR), and hypertriglyceridemia are common features observed in non-alcoholic fatty liver diseases (NAFLD). There is a critical medical necessity to find novel therapeutics that can halt the development of NAFLD.

METHODS

Bombax ceiba Linn. leaf extract was prepared and its phytochemical profile was determined. Standard and high carbohydrate high-fat diets (HCHF) were prepared. Rats were fed HCHF for 18 weeks to induce a non-alcoholic fatty liver (NAFL) model. Forty male rats were divided into control, B. ceiba Linn. leaf extract, NAFL, prophylactic, and treated groups. Serum fasting blood sugar (FBS), insulin, insulin resistance (HOMA-IR), cholesterol, high-density lipoprotein (HDL), triglycerides (TG), low density lipoprotein (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), intelectin-1 (ITLN1), p38 MAP kinase (MAPK), peroxisome proliferator-activated receptor alpha (PPAR-α), and interleukin-6 (IL-6) were evaluated.

RESULTS

Data obtained showed that HCHF-induced NAFL resulting in a significant increase in FBS, serum insulin, HOMA-IR, cholesterol, LDL, TG, ALT, AST, and IL-6 and a significant decrease in serum levels of HDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the control group. The analysis of B. ceiba Linn. leaf extract showed high content of phenol compounds which may cause a significant decrease in the levels of FBS, insulin, HOMA-IR values, lipid profile, and levels of IL-6 while a significant increase in serum levels of LDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the NAFL group.

CONCLUSIONS

B. ceiba Linn. Leaf extract is a highly protective and promising therapeutic agent against inflammation and oxidative stress in the NAFLD model induced by HCHF.

Developmental defects induced by thiabendazole are mediated via apoptosis, oxidative stress and alteration in PI3K/Akt and MAPK pathways in zebrafish

Thiabendazole, a benzimidazole fungicide, is widely used to prevent yield loss in agricultural land by inhibiting plant diseases derived from fungi. As thiabendazole has a stable benzimidazole ring structure, it remains in the environment for an extended period, and its toxic effects on non-target organisms have been reported, indicating the possibility that it could threaten public health. However, little research has been conducted to elucidate the comprehensive mechanisms of its developmental toxicity. Therefore, we used zebrafish, a representative toxicological model that can predict toxicity in aquatic organisms and mammals, to demonstrate the developmental toxicity of thiabendazole. Various morphological malformations were observed, including decreased body length, eye size, and increased heart and yolk sac edema. Apoptosis, reactive oxygen species (ROS) production, and inflammatory response were also triggered by thiabendazole exposure in zebrafish larvae. Furthermore, PI3K/Akt and MAPK signaling pathways important for appropriate organogenesis were significantly changed by thiabendazole. These results led to toxicity in various organs and a reduction in the expression of related genes, including cardiovascular toxicity, neurotoxicity, and hepatic and pancreatic toxicity, which were detected in flk1:eGFP, olig2:dsRED, and L-fabp:dsRed;elastase:GFP transgenic zebrafish models, respectively. Overall, this study partly determined the developmental toxicity of thiabendazole in zebrafish and provided evidence of the environmental hazards of this fungicide.

Inhibition of GSK3B phosphorylation improves glucose and lipid metabolism disorder

Hepatic glycolipid metabolism disorder is considered as one of the key pathogenic factors for many chronic diseases. Revealing the molecular mechanism of metabolic disorder and exploring drug targets are crucial for the treatment of glucose and lipid metabolic diseases. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been reported to be associated with the pathogenesis of various metabolic diseases. Herein, GAPDH-knockdown ZFL cells and GAPDH-downregulation zebrafish exhibited significant lipid deposition increase and glycogen reduction, thus inducing glucose and lipid metabolism disorders. Using high-sensitivity mass spectrometry-based proteomic and phosphoproteomic analysis, we identified 6838 proteins and 3738 phosphorylated proteins in GAPDH-knockdown ZFL cells. The protein-protein interaction network and DEPPs analyses showed that gsk3ba^Y216 were involved in lipid and glucose metabolism, which was verified by In vitro study. The enzyme activity analysis and cell staining results showed that HepG2 and NCTC-1469 cells transfected with GSK3B^Y216F plasmid had significantly lower glucose and insulin levels, the decreased lipid deposition, and the increased glycogen synthesis than those transfected with GSK3B^Y216E plasmid, suggesting that inhibition of GSK3B phosphorylation could significantly improve GSK3B hyperphosphorylation-induced glucose tolerance impairment and insulin sensitivity reduction. To our knowledge, this is the first multi-omic study of GAPDH-knockdown ZFL cells. This study provides insights into the molecular mechanism of glucose and lipid metabolic disorder, and provides potential targets (kinases) for the treatments of human glucose and lipid metabolic diseases.

Human milk-derived extracellular vesicles alleviate high fat diet-induced non-alcoholic fatty liver disease in mice

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD), characterized by excessive hepatic lipid accumulation, imposes serious challenges on public health worldwide. Breastfeeding has been reported to reduce the risk of NAFLD. Extracellular vesicles (EVs) are bilayer membrane vesicles released from various cells into the extracellular space, participating in multiple life processes. Whether EVs from human milk exert metabolic benefits against NAFLD is worth investigating.

METHODS AND RESULTS

In this study, the EVs were isolated from human milk collected from healthy mothers and quantified. Functional analyses were performed using the NAFLD mouse model and free fatty acid (FFA)-stimulated mouse primary hepatocytes. The results showed that human milk-derived EVs could effectively alleviate high fat diet-induced hepatic steatosis and insulin resistance in mice with NAFLD via inhibiting lipogenesis and increasing lipolysis. The FFA-induced lipid accumulation was also inhibited in hepatocytes after treatment with human milk-derived EVs. Mechanistically, the human milk derived-EVs cargo (proteins and miRNAs), which linked to lipid metabolism, may be responsible for these beneficial effects.

CONCLUSION

The findings of this study highlighted the therapeutic benefits of human milk-derived EVs and provided a new strategy for NAFLD treatment.

Effect of Isoquercitrin on Free Fatty Acid-Induced Lipid Accumulation in HepG2 Cells

Liver metabolic disorders and oxidative stress are crucial factors in the development of nonalcoholic fatty liver disease (NAFLD); however, treatment strategies to combat NAFLD remain poorly established, presenting an important challenge that needs to be addressed. Herein, we aimed to examine the effect of isoquercitrin on lipid accumulation induced by exogenous free fatty acids (FFA) using HepG2 cells and elucidate the underlying molecular mechanism. The cells were exposed to 0.5 mM FFA to induce intracellular lipid accumulation, followed by co-treatment with isoquercitrin to confirm the potential inhibitory effect on FFA-induced lipid production. HepG2 cells exposed to FFA alone exhibited intracellular lipid accumulation, compromised endoplasmic reticulum (ER) stress, and enhanced expression of proteins and genes involved in lipid synthesis; however, co-treatment with isoquercitrin decreased the expression of these molecules in a dose-dependent manner. Furthermore, isoquercitrin could activate AMP-activated protein kinase (AMPK), a key regulatory protein of hepatic fatty acid oxidation, suppressing new lipid production by phosphorylating acetyl-CoA carboxylase (ACC) and inhibiting sterol regulatory element-binding transcription factor 1 (SREBP-1)/fatty acid synthase (FAS) signals. Overall, these findings suggest that isoquercitrin can be employed as a therapeutic agent to improve NAFLD via the regulation of lipid metabolism by targeting the AMPK/ACC and SREBP1/FAS pathways.

HADHA alleviates hepatic steatosis and oxidative stress in NAFLD via inactivation of the MKK3/MAPK pathway

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a liver metabolic syndrome and still lacks effective treatments because the molecular mechanism underlying the development of NAFLD is not completely understood. We investigated the role of Hydroxyl CoA dehydrogenase alpha subunit (HADHA) in the pathogenesis of NAFLD.

METHODS

HADHA expression was detected both in NAFLD cell and mice, and knockdown of HADHA in free fatty acids (FFA)-treated L02 or overexpression of HADHA in high fat diet (HFD)-fed mice was used to detected the influence of HADHA on hepatic steatosis, mitochondrial dysfunction, and oxidative stress by regulating of MKK3/MAPK signaling.

RESULTS

Our data revealed that HADHA expression was decreased in FFA-treated L02 cells and in HFD-fed mice. Knockdown of HADHA markedly aggravated hepatic steatosis, inflammation and oxidative stress in FFA-treated L02 cells, which was associated with the activation of MKK3/MAPK signalling pathways. Moreover, oxidative stress and liver lesions were improved in NAFLD mice by upregulation of HADHA. Importantly, we demonstrated that overexpression of HADHA inhibited the expression of p-MAPK in NAFLD mice, reducing lipid accumulation and steatosis.

CONCLUSION

HADHA may function as a protective factor in the progression of NAFLD by alleviating abnormal metabolism and oxidative stress by suppressing MKK3/MAPK signalling pathway activation, providing a new target for the treatment of NAFLD.

Mitogen-Activated Protein Kinase Phosphatases: No Longer Undruggable?

Phosphatases and kinases maintain an equilibrium of dephosphorylated and phosphorylated proteins, respectively, that are required for critical cellular functions. Imbalance in this equilibrium or irregularity in their function causes unfavorable cellular effects that have been implicated in the development of numerous diseases. Protein tyrosine phosphatases (PTPs) catalyze the dephosphorylation of protein substrates on tyrosine residues, and their involvement in cell signaling and diseases such as cancer and inflammatory and metabolic diseases has made them attractive therapeutic targets. However, PTPs have proved challenging in therapeutics development, garnering them the unfavorable reputation of being undruggable. Nonetheless, great strides have been made toward the inhibition of PTPs over the past decade. Here, we discuss the advancement in small-molecule inhibition for the PTP subfamily known as the mitogen-activated protein kinase (MAPK) phosphatases (MKPs). We review strategies and inhibitor discovery tools that have proven successful for small-molecule inhibition of the MKPs and discuss what the future of MKP inhibition potentially might yield.

Repressing effect of transformed ginsenoside Rg3-mix against LPS-induced inflammation in RAW264.7 macrophage cells

BACKGROUND

Rg3-ginsenoside, a protopanaxadiol saponin, is a well-known adaptogen used for the prevention of cancer and inflammation. However, despite its distinct biological activity, the concentration of Rg3 in the total ginseng extract is insufficient for therapeutic applications. This study aims to convert PPD-class of major ginsenosides into a mixture of minor ginsenoside, to analyze its immune-regulatory role in macrophage cells.

RESULTS

Using heat and organic acid treatment, three major ginsenosides, Rc, Rd, and Rb1, were converted into a mixture of minor ginsenosides, GRg3-mix [Rg3(S), Rg3(R), Rg5, and Rk1]. Purity and content analysis of the transformed compound were performed using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), compared with their standards. Preceding with the anti-inflammatory activity of GRg3-mix, lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophage cells were treated with various concentrations of GRg3-mix (6.25, 12.5, 25, and 50 μg/mL). The cell viability assay revealed that the level of cell proliferation was increased, while the nitric oxide (NO) assay showed that NO production decreased dose-dependently in activated RAW264.7 cells. The obtained results were compared to those of pure Rg3(S) ≥ 98% (6.25, 12.5, and 25 μg/mL). Preliminary analysis of the CCK-8 and NO assay demonstrated that GRg3-mix can be used as an anti-inflammatory mediator, but mRNA and protein expression levels were evaluated for further confirmation. The doses of GRg3-mix significantly suppressed the initially upregulated mRNA and protein expression of inflammation-related enzymes and cytokines, namely inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear transcription factor kappa B (NF-κB), tumor necrosis factor (TNF-α), and interleukins (IL-6 and IL1B), as measured by reverse transcription-polymerase chain reaction and western blotting.

CONCLUSIONS

Our pilot data confirmed that the mixture of minor ginsenosides, namely GRg3-mix, has high anti-inflammatory activity and has an easy production procedure.

Uncovering the effect and mechanism of Panax notoginseng saponins on metabolic syndrome by network pharmacology strategy

ETHNOPHARMACOLOGICAL RELEVANCE

Metabolic syndrome (MetS) is a cluster of disease centered on obesity, which is the result of stagnation of liver qi according to traditional Chinese medicine. Panax notoginseng is a traditional Chinese herbal medicine, entering liver and stomach meridians and dissipating blood stasis, in which panax notoginseng saponins (PNS) are the main active components. However, its effects and mechanism on metabolic syndrome has not been revealed yet.

AIM OF STUDY

To evaluate the anti-MetS effect of PNS, including body weight and adiposity, glucose metabolism and non-alcoholic fatty liver disease (NAFLD), as well as to explore the mechanism and signaling pathway of PNS on MetS effect.

MATERIALS AND METHODS

HPLC was utilized to affirm the percentages of saponins in PNS. In vivo, normal C57BL/6J mice and high-fat diet (HFD)-induced MetS mice were used to evaluate anti-MetS effect of PNS. Body weight, food and water intake were recorded. NMR imager was used for NMR imaging and lipid-water analysis. Blood glucose detection, glucose and insulin tolerance test were performed to evaluate glucose metabolism. Biochemical indexes analysis and histopathological staining were used to evaluate the effect on NAFLD. The expressions of mRNA and proteins related to thermogenesis in adipose tissue were determined using real-time PCR and Western blot. In silico, network pharmacology was utilized to predict potential mechanism. In vitro, matured 3T3-L1 adipocyte was used as subject to confirm the signaling pathway by Western blot.

RESULTS

We determined the content of PNS component by HPLC. In vivo, PNS could improve metabolic syndrome with weight loss, reduction of adiposity, improvement of adipose distribution, correction of glucose metabolism disorder and attenuation of NAFLD. Mechanismly, PNS boosted energy exhaustion and dramatically enhanced thermogenesis in brown adipose tissue (BAT), induced white adipose tissue (WAT) browning. In silico, utilizing network pharmacology strategy, we identified 307 candidate targets which were enriched in MAPK signaling pathway specifically in liver tissue and adipocyte. In vitro validation confirmed ERK and p38MAPK mediated anti-MetS effects of PNS, not JNK signaling pathway.

CONCLUSION

PNS exerted protective effect on metabolic syndrome through MAPK-mediated adipose thermogenic activation, which may serve as a prospective therapeutic drug for metabolic syndrome.

Comparative effects of thymol and vitamin E on nonalcoholic fatty liver disease in male Wistar rats

Following the obesity epidemics, nonalcoholic fatty liver disease (NAFLD) has grown in prevalence and become a main cause of morbidity and death, intimately linked to cardiovascular disease, cancer, and cirrhosis. The key factor in the evolution of NAFLD is thought to be oxidative stress. Because most patients cannot change their lifestyle or dietary habits, a pharmaceutical strategy is now required to treat NAFLD. Nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis, is treated with vitamin E. (NASH). Vitamin E is also a powerful antioxidant that has been demonstrated to lower oxidative stress in people with NAFLD. Thymol is a monoterpene phenol with a variety of pharmacological effects, however its anti-fatty liver properties have yet to be investigated. Despite the fact that oxidative stress is thought to have a role in the etiology of nonalcoholic steatohepatitis, antioxidant therapies have not been well studied in the treatment of nonalcoholic steatohepatitis. The goal was to learn more about vitamin E and thymol's biological activities, with a particular emphasis on their therapeutic effectiveness in NAFLD. Four groups of thirty-two adult male rats were formed (healthy control, thymol, Vit E, and fatty liver). For 28 days, rats were given either oral vitamin E (200 mg/kg) or thymol (50 mg/kg) randomly. The levels of ALT, AST, TNF- α, Ferritin, CK-MB enzymes, and MAPK gene expression were then determined in the serum. Based on a random effect model analysis, at the end of 28 days of therapy, ALT (41.43 U/L), AST (47.91 U/L), Ferritin (1.13 pg/dl), CK-MB (251.22 IU/L), TNF-α (95.39 pg/mL) (p≤0.001), and MAPK gene expression levels (p≤0.05) significantly reduced in both experimental groups compared with the fatty liver group. Vitamin E and thymol therapy is a safe, affordable, and effective therapeutic option in the fatty liver group. Patients with fatty liver disease should be encouraged to take vitamin E and Thymol supplements, which are both safe and affordable, because more effective new therapeutic options are lacking.

Defining the structure-activity relationship for a novel class of allosteric MKP5 inhibitors

Mitogen-activated protein kinase (MAPK) phosphatase 5 (MKP5) is responsible for regulating the activity of the stress-responsive MAPKs and has been put forth as a potential therapeutic target for a number of diseases, including dystrophic muscle disease a fatal rare disease which has neither a treatment nor cure. In previous work, we identified Compound 1 (3,3-dimethyl-1-((9-(methylthio)-5,6-dihydrothieno[3,4-h]quinazolin-2-yl)thio)butan-2-one) as the lead compound of a novel class of MKP5 inhibitors. In this work, we explore the structure-activity relationship for inhibition of MKP5 through modifications to the scaffold and functional groups present in 1. A series of derivative compounds was designed, synthesized, and evaluated for inhibition of MKP5. In addition, the X-ray crystal structures of six enzyme-inhibitor complexes were solved, further elucidating the necessary requirements for MKP5 inhibition. We found that the parallel-displaced π-π interaction between the inhibitor three-ring core and Tyr435 is critical for modulating potency, and that modifications to the core and functionalization at the C-9 position are essential for ensuring proper positioning of the core for this interaction. These results lay the foundation from which more potent MKP5 allosteric inhibitors can be developed for potential therapeutics towards the treatment of dystrophic muscle disease.

Misuse of Cardiac Lipid upon Exposure to Toxic Trace Elements-A Focused Review

Heavy metals and metalloids like cadmium, arsenic, mercury, and lead are frequently found in the soil, water, food, and atmosphere; trace amounts can cause serious health issues to the human organism. These toxic trace elements (TTE) affect almost all the organs, mainly the heart, kidney, liver, lungs, and the nervous system, through increased free radical formation, DNA damage, lipid peroxidation, and protein sulfhydryl depletion. This work aims to advance our understanding of the mechanisms behind lipid accumulation via increased free fatty acid levels in circulation due to TTEs. The increased lipid level in the myocardium worsens the heart function. This dysregulation of the lipid metabolism leads to damage in the structure of the myocardium, inclusive fibrosis in cardiac tissue, myocyte apoptosis, and decreased contractility due to mitochondrial dysfunction. Additionally, it is discussed herein how exposure to cadmium decreases the heart rate, contractile tension, the conductivity of the atrioventricular node, and coronary flow rate. Arsenic may induce atherosclerosis by increasing platelet aggregation and reducing fibrinolysis, as exposure interferes with apolipoprotein (Apo) levels, resulting in the rise of the Apo-B/Apo-A1 ratio and an elevated risk of acute cardiovascular events. Concerning mercury and lead, these toxicants can cause hypertension, myocardial infarction, and carotid atherosclerosis, in association with the generation of free radicals and oxidative stress. This review offers a complete overview of the critical factors and biomarkers of lipid and TTE-induced cardiotoxicity useful for developing future protective interventions.

Hepatoprotective Role of Carvedilol against Ischemic Hepatitis Associated with Acute Heart Failure via Targeting miRNA-17 and Mitochondrial Dynamics-Related Proteins: An In Vivo and In Silico Study

Acute heart failure (AHF) is one of the most common diseases in old age that can lead to mortality. Systemic hypoperfusion is associated with hepatic ischemia–reperfusion injury, which may be irreversible. Ischemic hepatitis due to AHF has been linked to the pathogenesis of liver damage. In the present study, we extensively investigated the role of mitochondrial dynamics-related proteins and their epigenetic regulation in ischemic liver injury following AHF and explored the possible hepatoprotective role of carvedilol. The biochemical analysis revealed that the ischemic liver injury following AHF significantly elevated the activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) enzymes, the level of total and direct bilirubin, and the expression of hepatic mitogen-activated protein kinase (MAPK), dynamin-1-like protein (DNM1L), and hepatic miRNA-17. At the same time, it significantly reduced the serum albumin level, the activity of hepatic superoxide dismutase (SOD), and the expression of mitochondrial peroxisome proliferator-activated receptor-1α (PGC-1α), and mitofusin 2 (Mtf2). The histological examination of the liver tissue revealed degenerated hepatocytes. Interestingly, administration of carvedilol either prior to or after isoprenaline-induced AHF significantly improved the liver function and reversed the deterioration effect of AHF-induced ischemic hepatitis, as demonstrated by biochemical, immunohistochemical, and histological analysis. Our results indicated that the hepatoprotective effect of carvedilol in ameliorating hepatic ischemic damage could be attributed to its ability to target the mitochondrial dynamics-related proteins (Mtf2, DNM1L and PGC-1α), but also their epigenetic regulator miRNA-17. To further explore the mode of action of carvedilol, we have investigated, in silico, the ability of carvedilol to target dynamin-1-like protein and mitochondrial dynamics protein (MID51). Our results revealed that carvedilol has a high binding affinity (−14.83 kcal/mol) toward the binding pocket of DNM1L protein. In conclusion, our study highlights the hepatoprotective pharmacological application of carvedilol to attenuate ischemic hepatitis associated with AHF.

Nootkatone, a Sesquiterpene Ketone From Alpiniae oxyphyllae Fructus, Ameliorates Metabolic-Associated Fatty Liver by Regulating AMPK and MAPK Signaling

Metabolic-associated fatty liver disease (MAFLD) is becoming more common due to lifestyle changes. A long-term high-fat and high-glucose diet induces glycolipid metabolism disorders in the liver, which results in the development of MAFLD. To date, there is no specific clinically useful therapeutics for this disease. Natural products or synthetic compounds were screened and investigated to find effective agents for treating MAFLD. In this study, nootkatone (Nok), a natural sesquiterpene ketone isolated from Alpiniae oxyphyllae fructus, was explored for its potential to treat MAFLD, and underlying mechanisms were studied. Our results show that Nok dramatically ameliorated the disordered lipid and glucose metabolism in MAFLD mice, decreased fat accumulation in hepatic tissue, and improved liver injury. Inflammation, metabolic disorder, and oxidative stress were ameliorated in liver tissue based on RNA-seq transcriptome comparison between a Nok-treated group and an MAFLD model group. Furthermore, Nok significantly activated AMPK activity and inhibited MAPK activity, especially the p38 and JNK signaling pathways, in vivo based on western blot analysis. The pharmaceutical effects and potential signaling pathways impacted by Nok were also investigated in L02 cells. Nok significantly promoted the consumption of glucose and decreased the deposition of triglycerides in vitro. The p-AMPKα level was notably upregulated by Nok, indicating dramatic AMPK activation. In addition, Nok decreased the levels of p-ERK1/2, p-p38, and p-JNK. Nok also inhibited the activation of MAPK signaling and, thus, alleviated MAFLD development. Our results suggest that Nok may be useful in treating MAFLD. Nok may ameliorate MAFLD by regulating glycolipid metabolism disorders by activating AMPK and inhibiting MAPK activity. Collectively, this study suggests that Nok is an effective compound for the treatment of MAFLD.

The role of protein kinases as key drivers of metabolic dysfunction-associated fatty liver disease progression: New insights and future directions

Metabolic dysfunction-associated fatty liver disease (MAFLD), proposed in 2020 is a novel term for non-alcoholic fatty liver disease (NAFLD) which was coined for the first time in 1980. It is a leading cause of the most chronic liver disease and hepatic failure all over the world, and unfortunately, with no licensed drugs for treatment yet. The progress of the disease is driven by the triggered inflammatory process, oxidative stress, and insulin resistance in many pathways, starting with simple hepatic steatosis to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and liver cancer. Protein kinases (PKs), such as MAPK, ErbB, PKC, PI3K/Akt, and mTOR, govern most of the pathological pathways by acting on various downstream key points in MAFLD and regulating both hepatic gluco- lipo-neogenesis and inflammation. Therefore, modulating the function of those potential protein kinases that are effectively involved in MAFLD might be a promising therapeutic approach for tackling this disease. In the current review, we have discussed the key role of protein kinases in the pathogenesis of MAFLD and performed a protein-protein interaction (PPI) network among the main proteins of each kinase pathway with MAFLD-related proteins to predict the most likely targets of the PKs in MAFLD. Moreover, we have reported the experimental, pre-clinical, and clinical data for the most recent investigated molecules that are activating p38-MAPK and AMPK proteins and inhibiting the other PKs to improve MAFLD condition by regulating oxidation and inflammation signalling.

Metabolic Impact of MKP-2 Upregulation in Obesity Promotes Insulin Resistance and Fatty Liver Disease

The mechanisms connecting obesity with type 2 diabetes, insulin resistance, nonalcoholic fatty liver disease, and cardiovascular diseases remain incompletely understood. The function of MAPK phosphatase-2 (MKP-2), a type 1 dual-specific phosphatase (DUSP) in whole-body metabolism, and how this contributes to the development of diet-induced obesity, type 2 diabetes (T2D), and insulin resistance is largely unknown. We investigated the physiological contribution of MKP-2 in whole-body metabolism and whether MKP-2 is altered in obesity and human fatty liver disease using MKP-2 knockout mice models and human liver tissue derived from fatty liver disease patients. We demonstrate that, for the first time, MKP-2 expression was upregulated in liver tissue in humans with obesity and fatty liver disease and in insulin-responsive tissues in mice with obesity. MKP-2-deficient mice have enhanced p38 MAPK, JNK, and ERK activities in insulin-responsive tissues compared with wild-type mice. MKP-2 deficiency in mice protects against diet-induced obesity and hepatic steatosis and was accompanied by improved glucose homeostasis and insulin sensitivity. Mkp-2^−/− mice are resistant to diet-induced obesity owing to reduced food intake and associated lower respiratory exchange ratio. This was associated with enhanced circulating insulin-like growth factor-1 (IGF-1) and stromal cell-derived factor 1 (SDF-1) levels in Mkp-2^−/− mice. PTEN, a negative regulator of Akt, was downregulated in livers of Mkp-2^−/− mice, resulting in enhanced Akt activity consistent with increased insulin sensitivity. These studies identify a novel role for MKP-2 in the regulation of systemic metabolism and pathophysiology of obesity-induced insulin resistance and fatty liver disease.

Inhibition of MAP4K4 Signaling Initiaties Metabolic Reprogramming to Protect Hepatocytes from Lipotoxic Damage

The primary hepatic consequence of obesity is non-alcoholic fatty liver disease (NAFLD), affecting about 25% of the global adult population. Non-alcoholic steatohepatitis (NASH) is a severe form of NAFLD characterized by liver lipid accumulation, inflammation, and hepatocyte ballooning, with a different degree of hepatic fibrosis. In the light of rapidly increasing prevalence of NAFLD and NASH, there is an urgent need for improved understanding of the molecular pathogenesis of these diseases. The aim of this study was to decipher the possible role of STE20-type kinase MAP4K4 in the regulation of hepatocellular lipotoxicity and susceptibility to NAFLD. We found that MAP4K4 mRNA expression in human liver biopsies was positively correlated with key hallmarks of NAFLD (i.e., liver steatosis, lobular inflammation, hepatocellular ballooning, and fibrosis). We also found that the silencing of MAP4K4 suppressed lipid deposition in human hepatocytes by stimulating β-oxidation and triacylglycerol secretion, while attenuating fatty acid influx and lipid synthesis. Furthermore, downregulation of MAP4K4 markedly reduced the glycolysis rate and lowered incidences of oxidative/endoplasmic reticulum stress. In parallel, we observed suppressed JNK and ERK and increased AKT phosphorylation in MAP4K4-deficient hepatocytes. Together, these results provide the first experimental evidence supporting the potential involvement of STE20-type kinase MAP4K4 as a component of the hepatocellular lipotoxic milieu promoting NAFLD susceptibility.

OTUB1 alleviates NASH through inhibition of the TRAF6-ASK1 signaling pathways

BACKGROUND AND AIMS

NAFLD is considered as the hepatic manifestation of the metabolic syndrome, which includes insulin resistance, obesity and hyperlipidemia. NASH is a progressive stage of NAFLD with severe hepatic steatosis, hepatocyte death, inflammation, and fibrosis. Currently, no pharmacological interventions specifically tailored for NASH are approved. Ovarian tumor domain, ubiquitin aldehyde binding 1 (OTUB1), the founding member of deubiquitinases, regulates many metabolism-associated signaling pathways. However, the role of OTUB1 in NASH is unclarified.

METHODS AND RESULTS

We demonstrated that mice with Otub1 deficiency exhibited aggravated high-fat diet-induced and high-fat high-cholesterol (HFHC) diet-induced hyperinsulinemia and liver steatosis. Notably, hepatocyte-specific overexpression of Otub1 markedly alleviated HFHC diet-induced hepatic steatosis, inflammatory responses, and liver fibrosis. Mechanistically, we identified apoptosis signal-regulating kinase 1 (ASK1) as a key candidate target of OTUB1 through RNA-sequencing analysis and immunoblot analysis. Through immunoprecipitation-mass spectrometry analysis, we further found that OTUB1 directly bound to tumor necrosis factor receptor-associated factor 6 (TRAF6) and suppressed its lysine 63-linked polyubiquitination, thus inhibiting the activation of ASK1 and its downstream pathway.

CONCLUSIONS

OTUB1 is a key suppressor of NASH that inhibits polyubiquitinations of TRAF6 and attenuated TRAF6-mediated ASK1 activation. Targeting the OTUB1-TRAF6-ASK1 axis may be a promising therapeutic strategy for NASH.

Burmese pythons exhibit a transient adaptation to nutrient overload that prevents liver damage

As an opportunistic predator, the Burmese python (Python molurus bivittatus) consumes large and infrequent meals, fasting for up to a year. Upon consuming a large meal, the Burmese python exhibits extreme metabolic responses. To define the pathways that regulate these postprandial metabolic responses, we performed a comprehensive profile of plasma metabolites throughout the digestive process. Following ingestion of a meal equivalent to 25% of its body mass, plasma lipoproteins and metabolites, such as chylomicra and bile acids, reach levels observed only in mammalian models of extreme dyslipidemia. Here, we provide evidence for an adaptive response to postprandial nutrient overload by the python liver, a critical site of metabolic homeostasis. The python liver undergoes a substantial increase in mass through proliferative processes, exhibits hepatic steatosis, hyperlipidemia-induced insulin resistance indicated by PEPCK activation and pAKT deactivation, and de novo fatty acid synthesis via FASN activation. This postprandial state is completely reversible. We posit that Burmese pythons evade the permanent hepatic damage associated with these metabolic states in mammals using evolved protective measures to inactivate these pathways. These include a transient activation of hepatic nuclear receptors induced by fatty acids and bile acids, including PPAR and FXR, respectively. The stress-induced p38 MAPK pathway is also transiently activated during the early stages of digestion. Taken together, these data identify a reversible metabolic response to hyperlipidemia by the python liver, only achieved in mammals by pharmacologic intervention. The factors involved in these processes may be relevant to or leveraged for remediating human hepatic pathology.

MicroRNA-29b ameliorates hepatic inflammation via suppression of STAT3 in alcohol-associated liver disease

Alcohol-associated liver disease (ALD) is induced by chronic excessive alcohol consumption resulting in the clinical manifestations of steatosis, inflammation, and cirrhosis. MicroRNA-29b (miR-29b) is mainly expressed in hepatic nonparenchymal cells, and its expression level varies in different diseases. In this study, we aimed to determine the role of miR-29b in a mouse model of alcohol-associated liver disease. Wild-type (WT) and miR-29b knockout (miR-29b^-/-) mice were fed a Lieber-DeCarli liquid diet containing 5% alcohol for 10 days, followed by gavage of a single dose of ethanol (5 g/kg body weight). Histology, immunoblotting, and biochemical analyses were then conducted for comparison. miR-29b expression was decreased in the livers of chronic-plus-binge ethanol-fed mice. Further analysis revealed that alcohol exposure exacerbated hepatic injury by significantly increasing serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, with decreased survival rates for miR-29b^-/- mice. Results from the luciferase assay indicated that miR-29b negatively regulated the signal transducer and activator of transcription 3 (STAT3). Depletion of miR-29b led to an increase in STAT3 and more noticeable inflammation in the liver, whereas overexpression of miR-29b downregulated STAT3 and proinflammatory cytokine expression in primary mouse peritoneal macrophages. Taken together, these results demonstrate a novel association between miR-29b and ALD. miR-29b plays a hepatoprotective role in alcohol-induced inflammation and liver injury by targeting STAT3.

Farnesoid X Receptor Deficiency Induces Hepatic Lipid and Glucose Metabolism Disorder via Regulation of Pyruvate Dehydrogenase Kinase 4

Farnesoid X receptors (FXR) are bile acid receptors that play roles in lipid, glucose, and energy homeostasis. Synthetic FXR-specific agonists have been developed for treating nonalcoholic fatty liver disease (NAFLD) patients. However, the detailed mechanism remains unclear. To investigate the effects of FXR on NAFLD and the possible mechanism, FXR-null mice were fed either a normal or a high-fat diet. The FXR-null mice developed hepatomegaly, steatosis, accumulation of lipid droplets in liver cells, glucose metabolism disorder, and elevated serum lipid levels. Transcriptomic results showed increased expression of key lipid synthesis and glucose metabolism-related proteins. We focused on pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme involved in the regulation of glucose and fatty acid (FA) metabolism and homeostasis. Subsequently, we confirmed an increase in PDK4 expression in FXR knockout cells. Moreover, inhibition of PDK4 expression alleviated lipid accumulation in hepatocytes caused by FXR deficiency in vivo and in vitro. Our results identify FXR as a nuclear transcription factor that regulates glucose and lipid metabolism balance through PDK4, providing further insights into the mechanism of FXR agonists in the treatment of metabolic diseases.

Hepatocyte glutathione S-transferase mu 2 prevents non-alcoholic steatohepatitis by suppressing ASK1 signaling

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. The advanced stage of NAFLD, non-alcoholic steatohepatitis (NASH), has been recognized as a leading cause of end-stage liver injury for which there are no FDA-approved therapeutic options. Glutathione S-transferase Mu 2 (GSTM2) is a phase II detoxification enzyme. However, the roles of GSTM2 in NASH have not been elucidated.

METHODS

Multiple RNA-seq analyses were used to identify hepatic GSTM2 expression in NASH. In vitro and in vivo gain- or loss-of-function approaches were used to investigate the role and molecular mechanism of GSTM2 in NASH.

RESULTS

We identified GSTM2 as a sensitive responder and effective suppressor of NASH progression. GSTM2 was significantly downregulated during NASH progression. Hepatocyte GSTM2 deficiency markedly aggravated insulin resistance, hepatic steatosis, inflammation and fibrosis induced by a high-fat diet and a high-fat/high-cholesterol diet. Mechanistically, GSTM2 sustained MAPK pathway signaling by directly interacting with apoptosis signal-regulating kinase 1 (ASK1). GSTM2 directly bound to the N-terminal region of ASK1 and inhibited ASK1 N-terminal dimerization to subsequently repress ASK1 phosphorylation and the activation of its downstream JNK/p38 signaling pathway under conditions of metabolic dysfunction.

CONCLUSIONS

These data demonstrated that hepatocyte GSTM2 is an endogenous suppressor that protects against NASH progression by blocking ASK1 N-terminal dimerization and phosphorylation. Activating GSTM2 holds promise as a therapeutic strategy for NASH.

CLINICAL TRIAL NUMBER

IIT-2021-277.

LAY SUMMARY

New therapeutic strategies for non-alcoholic steatohepatitis are urgently needed. We identified that the protein GSTM2 exerts a protective effect in response to metabolic stress. Therapies that aim to increase the activity of GSTM2 could hold promise for the treatment of non-alcoholic steatohepatitis.

Exercise suppresses mouse systemic AApoAII amyloidosis through enhancement of the p38 MAPK signaling pathway

Exercise interventions are beneficial for reducing the risk of age-related diseases, including amyloidosis, but the underlying molecular links remain unclear. Here, we investigated the protective role of interval exercise training in a mouse model of age-related systemic apolipoprotein A-II amyloidosis (AApoAII) and identified potential mechanisms. Mice subjected to sixteen weeks of exercise showed improved whole-body physiologic functions and exhibited substantial inhibition of amyloidosis, particularly in the liver and spleen. Exercise activated the hepatic p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway and the downstream transcription factor tumor suppressor p53. This activation resulted in elevated expression and phosphorylation of heat shock protein beta-1 (HSPB1), a chaperone that defends against protein aggregation. In amyloidosis-induced mice, the hepatic p38 MAPK-related adaptive responses were additively enhanced by exercise. We observed that with exercise, greater amounts of phosphorylated HSPB1 accumulated at amyloid deposition areas, which we suspect inhibits amyloid fibril formation. Collectively, our findings demonstrate the exercise-activated specific chaperone prevention of amyloidosis, and suggest that exercise may amplify intracellular stress-related protective adaptation pathways against age-associated disorders such as amyloidosis.

A high-fat High-fructose Diet Dysregulates the Homeostatic Crosstalk Between Gut Microbiome, Metabolome and Immunity in an Experimental Model of Obesity

SCOPE

Ample evidence supports the prominent role of gut-liver axis in perpetuating pathological networks of high-fat high-fructose (HFF) diet induced metabolic disorders, however, the molecular mechanisms are still not fully understood. Herein, we aim to present a holistic delineation and scientific explanation for the crosstalk between the gut and liver, including the potential mediators involved in orchestrating the metabolic and immune systems.

METHODS

An experimental obesity associated metaflammation rat model was induced with a HFF diet. An integrative multi-omics analysis was then performed. Following the clues illustrated by the multi-omics discoveries, putative pathways were subsequently validated by RT-qPCR and Western blotting.

RESULTS

HFF diet led to obese phenotypes in rats, as well as histopathological changes. Integrated omics analysis showed there existed a strong interdependence among gut microbiota composition, intestinal metabolites and innate immunity regulation in the liver. Some carboxylic acids might contribute to gut-liver communication. Moreover, activation of the hepatic LPS-TLR4 pathway in obesity was confirmed.

CONCLUSIONS

HFF-intake disturbs gut flora homeostasis. Crosstalk between gut microbiota and innate immune system mediated hepatic metaflammation in obese rats, associated with LPS-TLR4 signaling pathway activation. Moreover, α-hydroxyisobutyric acid and some other organic acids may play a role as messengers in the liver-gut axis. High-fat high-fructose diet (HFF) induces obesity associated chronic inflammation; HFF dysregulates the rat intestinal metabolome and gut microbiota composition; HFF impacts hepatic expression of genes involved in innate immunity; Modulation of gut microbiota composition and innate immunity are connected partly via TLR4 signalling; Small molecular carboxylic acids are potential mediators of gut-liver axis communication in chronic obesity. This article is protected by copyright. All rights reserved.