Vascular endothelial growth factor B exerts lipid-lowering effect by activating AMPK via VEGFR1

Knockdown of VEGF-B improves HFD-induced insulin resistance by enhancing glucose uptake in vascular endothelial cells via the PI3K/Akt pathway

Vascular endothelial growth factor B (VEGF-B) has been suggested to play a crucial role in regulating whole-body glucose homeostasis. However, the involved mechanisms are not fully understood. This study aimed to elucidate the regulatory effects and mechanisms of VEGF-B on glucose uptake in skeletal muscle, focusing on glucose uptake by skeletal muscle cells and vascular endothelial cells. Our results showed that a high-fat diet (HFD) induced significant increase in VEGF-B expression and decrease in glucose uptake by skeletal muscle, accompanied by elevated serum glucose levels. Interestingly, VEGF-B had no direct effect on glucose uptake by skeletal muscle cells (differentiated C2C12). Instead, VEGF-B inhibited glucose uptake of vascular endothelial cells bEnd.3 and subsequent trans-endothelial glucose transport, ultimately resulting in decreased glucose uptake by skeletal muscle cells. Furthermore, VEGF-B suppressed glucose uptake of vascular endothelial cells by downregulating the expression of glucose transporter 1 (GLUT1) through the VEGFR-PI3K/Akt signaling pathway. In vivo, knockdown of VEGF-B in skeletal muscle increased the HFD-impaired glucose uptake of skeletal muscle and improved the HFD-induced glucose intolerance and insulin resistance. This beneficial effect of VEGF-B knockdown was associated with the elevated expression of GLUT1 in the plasma membrane and the activation of the PI3K/Akt pathway in skeletal muscle. In conclusion, our findings demonstrated that knockdown of VEGF-B improved HFD-induced insulin resistance by enhancing glucose uptake in vascular endothelial cells via the PI3K/Akt pathway. These results highlighted the critical role of VEGF-B in regulating glucose uptake by vascular endothelial cells in skeletal muscle, providing a potential new target for improving obesity-induced glucose homeostasis imbalance.

VEGFB ameliorates insulin resistance in NAFLD via the PI3K/AKT signal pathway

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the most universal liver diseases with complicated pathogenesis throughout the world. Insulin resistance is a leading risk factor that contributes to the development of NAFLD. Vascular endothelial growth factor B (VEGFB) was described by researchers as contributing to regulating lipid metabolic disorders. Here, we investigated VEGFB as a main target to regulate insulin resistance and metabolic syndrome.

METHODS

In this study, bioinformatics, transcriptomics, morphological experiments, and molecular biology were used to explore the role of VEGFB in regulating insulin resistance in NAFLD and its molecular mechanism based on human samples, animal models, and cell models. RNA-seq was performed to analyze the signal pathways associated with VEGFB and NAFLD; Palmitic acid and High-fat diet were used to induce insulin-resistant HepG2 cells model and NAFLD animal model. Intracellular glucolipid contents, glucose uptake, hepatic and serum glucose and lipid levels were examined by Microassay and Elisa. Hematoxylin-eosin staining, Oil Red O staining, and Periodic acid-schiff staining were used to analyze the hepatic steatosis, lipid droplet, and glycogen content in the liver. Western blot and quantitative real-time fluorescent PCR were used to verify the expression levels of the VEGFB and insulin resistance-related signals PI3K/AKT pathway.

RESULTS

We observed that VEGFB is genetically associated with NAFLD and the PI3K/AKT signal pathway. After VEGFB knockout, glucolipids levels were increased, and glucose uptake ability was decreased in insulin-resistant HepG2 cells. Meanwhile, body weight, blood glucose, blood lipids, and hepatic glucose of NAFLD mice were increased, and hepatic glycogen, glucose tolerance, and insulin sensitivity were decreased. Moreover, VEGFB overexpression reduced glucolipids and insulin resistance levels in HepG2 cells. Specifically, VEGFB/VEGFR1 activates the PI3K/AKT signals by activating p-IRS1Ser307 expression, inhibiting p-FOXO1pS256 and p-GSK3Ser9 expressions to reduce gluconeogenesis and glycogen synthesis in the liver. Moreover, VEGFB could also enhance the expression level of GLUT2 to accelerate glucose transport and reduce blood glucose levels, maintaining glucose homeostasis.

CONCLUSIONS

Our studies suggest that VEGFB could present a novel strategy for treating NAFLD as a positive factor.

Molecular characterization of vascular endothelial growth factor b from spotted sea bass (Lateolabrax maculatus) and its potential roles in decreasing lipid deposition

Vascular endothelial growth factor B (VEGFB), a member of the VEGF family, exhibits limited angiogenic activity in mammals but plays an unexpected role in targeting lipids to peripheral tissues. However, its role in lipid metabolism in fish is unknown. In this study, the vegfb gene was cloned and characterized from spotted sea bass (Lateolabrax maculatus). It encodes 254 amino acids and possesses the typical characteristics of the Vegfb family, demonstrating high homology with those from other vertebrate species. The vegfb gene exhibits the highest expression levels in the liver, followed by the gills, intestine, and adipose tissues in spotted sea bass. In vivo, high-lipid diets decreased vegfb expression and increased lipid deposition in liver of fish. In vitro, palmitic acid + oleic acid treatment or vegfb knockdown significantly increased TG and TC contents, promoting lipid droplet deposition in hepatocytes. Vegfb overexpression has the opposite effects, inhibiting lipid deposition and downregulating fatty acid transport and adipogenesis genes. In contrast, the vegfb knockdown significantly upregulated the expression levels of c/ebpα, plin2, and dgat1 (P < 0.05). These results demonstrate that Vegfb may play an important role in reducing lipid deposition by regulating fatty acid transport and adipogenesis in the hepatocytes of spotted sea bass.

Role of vascular endothelial growth factor B in nonalcoholic fatty liver disease and its potential value

Nonalcoholic fatty liver disease (NAFLD) refers to fatty liver disease caused by liver injury factors other than alcohol. The disease is characterized by diffuse fat infiltration, including simple steatosis (no inflammatory fat deposition), nonalcoholic fatty hepatitis, liver fibrosis, and so on, which may cause liver cirrhosis, liver failure, and even liver cancer in the later stage of disease progression. At present, the pathogenesis of NAFLD is still being studied. The "two-hit" theory, represented by lipid metabolism disorder and inflammatory reactions, is gradually enriched by the "multiple-hit" theory, which includes multiple factors, such as insulin resistance and adipocyte dysfunction. In recent years, vascular endothelial growth factor B (VEGFB) has been reported to have the potential to regulate lipid metabolism and is expected to become a novel target for ameliorating metabolic diseases, such as obesity and type 2 diabetes. This review summarizes the regulatory role of VEGFB in the onset and development of NAFLD and illustrates its underlying molecular mechanism. In conclusion, the signaling pathway mediated by VEGFB in the liver may provide an innovative approach to the diagnosis and treatment of NAFLD.

The Role of VEGF Family in Lipid Metabolism

The vascular endothelial growth factor (VEGF) family plays a major role in tumors and ophthalmic diseases. However, increasingly more data reported its potential in regulating lipids. With its biological functions mainly expressed in lymphatic vessels, some factors in the families, like VEGF-A and VEGF-C, have been proved to regulate intestinal absorption of lipids by affecting chylous ducts. Other effects, including regulating lipoprotein lipase (LPL), endothelial lipase (EL), and recombinant syndecan 1 (SDC1), have also been confirmed. However, given the scant-related studies, further research should be conducted to examine the concrete mechanisms and provide pragmatic ways to apply them in the clinic. The VEGF family may treat dyslipidemia in specific ways that are different from common methods and concurrently contribute to the treatment of other metabolic diseases, like diabetes and obesity.

Therapeutic Potential of VEGF-B in Coronary Heart Disease and Heart Failure: Dream or Vision?

Coronary heart disease (CHD) is the leading cause of death around the world. Based on the roles of vascular endothelial growth factor (VEGF) family members to regulate blood and lymphatic vessels and metabolic functions, several therapeutic approaches have been attempted during the last decade. However proangiogenic therapies based on classical VEGF-A have been disappointing. Therefore, it has become important to focus on other VEGFs such as VEGF-B, which is a novel member of the VEGF family. Recent studies have shown the very promising potential of the VEGF-B to treat CHD and heart failure. The aim of this review article is to present the role of VEGF-B in endothelial biology and as a potential therapeutic agent for CHD and heart failure. In addition, key differences between the VEGF-A and VEGF-B effects on endothelial functions are demonstrated.

Reducing VEGFB expression regulates the balance of glucose and lipid metabolism in mice via VEGFR1

In recent years, studies have demonstrated that vascular endothelial growth factor B (VEGFB) can affect the metabolism of fatty acids and glucose, and it is expected to become a target for the diagnosis and treatment of metabolic diseases such as obesity and diabetes. At present, the specific mechanism that VEGFB regulates lipid and glucose metabolism balance is not completely understood. The present study used systemic VEGFB gene-knockout mice to investigate the effects of downregulation of the VEGFB gene on lipid metabolism and insulin secretion, and to explore the mechanism of the VEGFB pathway involved in the regulation of glucose and lipid metabolism. The morphological changes in the liver and pancreas of mice after VEGFB gene deletion were observed under a light microscope and a scanning electron microscope, and the effects of VEGFB gene deletion on lipid metabolism and blood glucose balance were detected by a serological technique. The detection indexes included total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol. Simultaneously, fasting blood glucose, glycosylated hemoglobin A1c (HbA1c), fasting insulin and glucagon were measured. Insulin sensitivity was assessed by using the insulin tolerance tests and glucose tolerance tests, and function of β-cell islets was evaluated by using the insulin resistance index (HOMA-IR) and pancreatic β-cell secretion index (HOMA-β). Τhe protein expression changes of vascular endothelial growth factor receptor 1 (VEGFR1) and vascular endothelial growth factor receptor 2 (VEGFR2) in mouse islets were detected by western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) after the VEGFB gene was knocked down to analyze the mechanism of VEGFB that may be involved in glucose and lipid metabolism. It was observed that after VEGFB was knocked down, mouse hepatocytes exhibited steatosis and increased secretory vesicles in islet cells. The lipid metabolism indexes such as TG, TC and LDL increased significantly; however, the levels of FBS, postprandial blood glucose and HbA1c decreased, whereas the glucose tolerance increased. Serum insulin secretion increased and HOMA-IR decreased since VEGFB was knocked down. Western blotting and RT-qPCR results revealed that the expression levels of VEGFR1 and neuropilin-1 decreased after the VEGFB gene was knocked down, while the expression levels of VEGFA and VEGFR2 increased. The absence of VEGFB may be involved in the regulation of glucose and lipid metabolism in mice by activating the VEGFA/VEGFR2 signaling pathway. VEGFB is expected to become a new target for the treatment of metabolic diseases such as obesity and diabetes. At present, the mechanism of VEGFB involved in regulating lipid metabolism and glucose metabolism is not completely clear. It was identified that downregulating VEGFB improved lipid metabolism and insulin resistance. The role of VEGFB/VEGFR1 pathway and other family members in regulating glucose and lipid metabolism was detected, which provided a theoretical and experimental basis for VEGFB to affect the regulation of glucose and lipid metabolism balance.

Reducing VEGFB accelerates NAFLD and insulin resistance in mice via inhibiting AMPK signaling pathway

Objective

Vascular endothelial growth factor B (VEGFB) was regarded to improve lipid metabolism and reduce obesity-related hyperlipidemia. Whether VEGFB participates in lipid metabolism in nonalcoholic fatty liver disease (NAFLD) has not been clear yet. This study investigated the involvement of VEGFB in lipid metabolism and insulin resistance via the AMPK signaling pathway in NAFLD.

Methods

We constructed the animal and cell model of NAFLD after VEGFB gene knockout to detect liver damage and metabolism in NAFLD. Bioinformatics analysis of VEGFB and the AMPK signaling pathway relative genes to verify the differential proteins. And mRNA levels of NAFLD fatty acid metabolism-related genes were detected.

Results

After the systemic VEGFB knockout mice were fed with high fat, the body fat, serum lipoprotein, NAFLD score, and insulin resistance were increased. Animal and cell experiments showed that the expression levels of phosphorylated proteins of CaMKK2 and AMPK decreased, the expression of proteins related to AMPK/ACC/CPT1 signaling pathway decreased, and the target genes CPT1α and Lcad decreased accordingly, reducing fatty acid oxidation in hepatocyte mitochondria; The expression of AMPK/SREBP1/Scd1 signaling pathway relative proteins increased, ACC1 and FAS increased correspondingly, which increased lipid synthesis in the endoplasmic reticulum.

Conclusion

VEGFB can participate in lipid metabolism and insulin resistance of NAFLD through the AMPK signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03540-2.

The Role of the VEGF Family in Atherosclerosis Development and Its Potential as Treatment Targets

The vascular endothelial growth factor (VEGF) family, the crucial regulator of angiogenesis, lymphangiogenesis, lipid metabolism and inflammation, is involved in the development of atherosclerosis and further CVDs (cardiovascular diseases). This review discusses the general regulation and functions of VEGFs, their role in lipid metabolism and atherosclerosis development and progression. These functions present the great potential of applying the VEGF family as a target in the treatment of atherosclerosis and related CVDs. In addition, we discuss several modern anti-atherosclerosis VEGFs-targeted experimental procedures, drugs and natural compounds, which could significantly improve the efficiency of atherosclerosis and related CVDs' treatment.

The Role of the VEGF Family in Coronary Heart Disease

The vascular endothelial growth factor (VEGF) family, the regulator of blood and lymphatic vessels, is mostly investigated in the tumor and ophthalmic field. However, the functions it enjoys can also interfere with the development of atherosclerosis (AS) and further diseases like coronary heart disease (CHD). The source, regulating mechanisms including upregulation and downregulation, target cells/tissues, and known functions about VEGF-A, VEGF-B, VEGF-C, and VEGF-D are covered in the review. VEGF-A can regulate angiogenesis, vascular permeability, and inflammation by binding with VEGFR-1 and VEGFR-2. VEGF-B can regulate angiogenesis, redox, and apoptosis by binding with VEGFR-1. VEGF-C can regulate inflammation, lymphangiogenesis, angiogenesis, apoptosis, and fibrogenesis by binding with VEGFR-2 and VEGFR-3. VEGF-D can regulate lymphangiogenesis, angiogenesis, fibrogenesis, and apoptosis by binding with VEGFR-2 and VEGFR-3. These functions present great potential of applying the VEGF family for treating CHD. For instance, angiogenesis can compensate for hypoxia and ischemia by growing novel blood vessels. Lymphangiogenesis can degrade inflammation by providing exits for accumulated inflammatory cytokines. Anti-apoptosis can protect myocardium from impairment after myocardial infarction (MI). Fibrogenesis can promote myocardial fibrosis after MI to benefit cardiac recovery. In addition, all these factors have been confirmed to keep a link with lipid metabolism, the research about which is still in the early stage and exact mechanisms are relatively obscure. Because few reviews have been published about the summarized role of the VEGF family for treating CHD, the aim of this review article is to present an overview of the available evidence supporting it and give hints for further research.