Adipose-derived stem cells promote glycolysis and peritoneal metastasis via TGF-ß1/SMAD3/ANGPTL4 axis in colorectal cancer.

Peritoneal metastasis, the third most common metastasis in colorectal cancer (CRC), has a poor prognosis for the rapid progression and limited therapeutic strategy. However, the molecular characteristics and pathogenesis of CRC peritoneal metastasis are poorly understood. Here, we aimed to elucidate the action and mechanism of adipose-derived stem cells (ADSCs), a prominent component of the peritoneal microenvironment, in CRC peritoneal metastasis formation. Database analysis indicated that ADSCs infiltration was increased in CRC peritoneal metastases, and high expression levels of ADSCs marker genes predicted a poor prognosis. Then we investigated the effect of ADSCs on CRC cells in vitro and in vivo. The results revealed that CRC cells co-cultured with ADSCs exhibited stronger metastatic property and anoikis resistance, and ADSCs boosted the intraperitoneal seeding of CRC cells. Furthermore, RNA sequencing was carried out to identify the key target gene, angiopoietin like 4 (ANGPTL4), which was upregulated in CRC specimens, especially in peritoneal metastases. Mechanistically, TGF-ß1 secreted by ADSCs activated SMAD3 in CRC cells, and chromatin immunoprecipitation assay showed that SMAD3 facilitated ANGPTL4 transcription by directly binding to ANGPTL4 promoter. The ANGPTL4 upregulation was essential for ADSCs to promote glycolysis and anoikis resistance in CRC. Importantly, simultaneously targeting TGF-ß signaling and ANGPTL4 efficiently reduced intraperitoneal seeding in vivo. In conclusion, this study indicates that tumor-infiltrating ADSCs promote glycolysis and anoikis resistance in CRC cells and ultimately facilitate peritoneal metastasis via the TGF-ß1/SMAD3/ANGPTL4 axis. The dual-targeting of TGF-ß signaling and ANGPTL4 may be a feasible therapeutic strategy for CRC peritoneal metastasis.

T266M variants of ANGPTL4 improve lipid metabolism by modifying their binding affinity to acetyl-CoA carboxylase in obstructive sleep apnea.

BACKGROUND: Angiopoietin-like protein 4 (ANGPTL4) is recognized as a crucial regulator in lipid metabolism. Acetyl-CoA carboxylases (ACACAs) play a role in the ß-oxidation of fatty acids. Yet, the functions of ANGPTL4 and ACACA in dyslipidemia of obstructive sleep apnea (OSA) remain unclear. METHODS: This study included 125 male OSA subjects from the Shanghai Sleep Health Study (SSHS) who were matched for age, body mass index (BMI), and lipid profile. Serum ANGPTL4 levels were measured via ELISA. The ANGPTL4 T266M variants of 4455 subjects along with their anthropometric, fasting biochemical, and standard polysomnographic parameters were collected. Linear regression was used to analyze the associations between quantitative traits and ANGPTL4 T266M. Molecular docking and molecular dynamic simulation were employed to compare the effects of the wild-type ANGPTL4 and its T266M mutation on ACACA. RESULTS: Serum ANGPTL4 levels significantly decreased with increasing OSA severity (non-OSA: 59.6 ± 17.4 ng/mL, mild OSA: 50.0 ± 17.5 ng/mL, moderate OSA: 46.3 ± 15.5 ng/mL, severe OSA: 19.9 ± 14.3 ng/mL, respectively, p = 6.02 × 10-16). No associations were found between T266M and clinical characteristics. Molecular docking indicated that mutant ANGTPL4 T266M had stronger binding affinity for the ACACA protein, compared with wild-type ANGPTL4. In terms of protein secondary structure, mutant ANGTPL4 T266M demonstrated greater stability than wild-type ANGPTL4. CONCLUSIONS: Serum ANGTPL4 levels were significantly decreased in OSA patients, particularly among individuals with severe OSA. Although functional ANGTPL4 T266M variants were not associated with lipid levels in OSA, ANGTPL4 T266M could enhance binding affinity for the ACACA protein, potentially regulating lipid metabolism.

Characterization of sexual dimorphism in ANGPTL4 levels and function.

ANGPTL4 is an attractive pharmacological target for lowering plasma triglycerides and cardiovascular risk. Since most preclinical studies on ANGPTL4 were performed in male mice, little is known about sexual dimorphism in ANGPTL4 regulation and function. Here, we aimed to study potential sexual dimorphism in ANGPTL4 mRNA and protein levels and ANGPTL4 function. Additionally, we performed exploratory studies on the function of ANGPTL4 in the liver during fasting using Angptl4-transgenic and Angptl4-/- mice. Compared to female mice, male mice showed higher hepatic and adipose ANGPTL4 mRNA and protein levels, as well as a more pronounced effect of genetic ANGPTL4 modulation on plasma lipids. By contrast, very limited sexual dimorphism in ANGPTL4 levels was observed in human liver and adipose tissue. In human and mouse adipose tissue, ANGPTL8 mRNA and/or protein levels were significantly higher in females than males. Adipose LPL protein levels were higher in female than male Angptl4-/- mice, which was abolished by ANGPTL4 (over) expression. At the human genetic level, the ANGPTL4 E40K loss-of-function variant was associated with similar plasma triglyceride reductions in women and men. Finally, ANGPTL4 ablation in fasted mice was associated with changes in hepatic gene expression consistent with PPARα activation. In conclusion, the levels of ANGPTL4 and the magnitude of the effect of ANGPTL4 on plasma lipids exhibit sexual dimorphism. Nonetheless, inactivation of ANGPTL4 should confer a similar metabolic benefit in women and men. Expression levels of ANGPTL8 in human and mouse adipose tissue are highly sexually dimorphic, showing higher levels in females than males.

Correlation between the serum FABP4, ANGPTL3, and ANGPTL4 levels and coronary artery disease.

BACKGROUND: Lipid metabolism related factors, such as angiopoietin-like protein 3 (ANGPTL3), angiopoietin-like 4 (ANGPTL4), fatty acid-binding protein 4 (FABP4) are newly discovered factors that can affect coronary artery disease (CAD). In this study, we aimed to investigate the relationship between CAD and these lipid metabolism factors. HYPOTHESIS: ANGPTL3, ANGPTL4, and FABP4 may provide a new method for the control of CAD risk factors and the prevention and treatment of CAD. METHODS: We enrolled 284 consecutive inpatients with suspected CAD and divided them into CAD and non-CAD groups based on the coronary angiography results. Serum ANGPTL3, ANGPTL4, FABP4, and tumor necrosis factor-α (TNF-α) levels were estimated using the enzyme-linked immunosorbent assay. Multivariate logistic regression was used to assess the risk factors for CAD. The receiver operating characteristic curve was used to determine the cutoff and diagnostic values. RESULTS: The serum TNF-α, FABP4, ANGPTL3, and ANGPTL4 values showed a significant difference between the CAD and non-CAD groups (p < .05). After adjusting for confounding factors, the FABP4, ANGPTL3, and ANGPTL4 levels were independently associated with CAD (p < .05). The ANGPTL3 expression level was an independent risk factor for CAD in patients with hypertension, but not in those without hypertension. The ANGPTL3 > 67.53 ng/mL, ANGPTL4 > 29.95 ng/mL, and FABP4 > 1421.25 ng/L combination had the highest diagnostic value for CAD. CONCLUSION: ANGPTL3, ANGPTL4, and FABP4 were identified as independent risk factors for CAD and have valuable clinical implications for the diagnosis and treatment of CAD.

Angiopoietin-Related Protein 4-Transcript 3 Increases the Proliferation, Invasion, and Migration of Hepatocellular Carcinoma Cells and Inhibits Apoptosis.

To investigate the functional differences of angiopoietin-related protein 4 (ANGPTL4) transcripts in hepatocellular carcinoma (HCC) cells. By transfecting ANGPTL4-Transcript 1 and ANGPTL4-Transcript 3 overexpression vectors into HepG2 and Huh7 cell lines with ANGPTL4 knockdown, the effects of overexpression of two transcripts on cell viability, invasion, migration, and apoptosis were analyzed. The expression of two transcripts was compared in human liver cancer tissue, and their effects on tumor development were validated in vivo experiments in mice. Compared with control, the overexpression of ANGPTL4-Transcript 1 had no significant effect on viability, invasion, healing, and apoptosis of HepG2 and Huh7 cells. However, these two cell lines overexpressing ANGPTL4-Transcript 3 showed remarkably enhanced cell viability, invasive and healing ability, and decreased apoptosis ability. Furthermore, the mRNA level of ANGPTL4-Transcript 3 was significantly increased in human HCC tissues and promoted tumor growth compared with Transcript 1. Different transcripts of gene ANGPTL4 have distinct effects on HCC. The abnormally elevated Transcript 3 with the specific ability of promoting HCC proliferation, infiltration, and migration is expected to become a new biological marker and more precise intervention target for HCC.

Knockdown of ANGPTL4 inhibits adipogenesis of preadipocyte via autophagy.

It has been demonstrated that angiopoietin-like protein 4 (ANGPTL4) plays an important regulatory role in lipid metabolism and backfat deposition appears to vary in different pig breeds. However, the correlation between ANGPTL4 and backfat deposition have not been well characterized and the role of ANGPTL4 in regulating adipogenesis remains unclear. Therefore, this study aimed to investigate correlation between ANGPTL4 and backfat deposition and to explore the effects of ANGPTL4 on preadipocyte differentiation and the underlying mechanism. Our results showed that the backfat thickness and the ANGPTL4 gene expression of Laiwu pigs were significantly higher than those in DLY pigs and the ANGPTL4 gene expression was positively correlated with backfat thickness both in DLY pigs and Laiwu pigs. Moreover, an increase in ANGPTL4 expression and activation of autophagy were observed during the differentiation of stromal vascular fraction cells. In addition, knockdown of ANGPTL4 inhibited the differentiation of 3T3-L1 cells with decreased expression of LC3-II and ATG5 and increased expression of SQSTM1, suggesting the involvement of autophagy in ANGPTL4-mediated adipogenesis. In conclusion, these results suggested that ANGPTL4 is positively correlated with backfat deposition in pigs and knockdown of ANGPTL4 inhibits adipogenesis of preadipocyte via autophagy, providing new insights into the regulation of fat deposition and to improve the carcass quality and meat quality of porcine.

Construction of an Anoikis-Related Gene Prognostic Signature and Identification of ANGPTL4 as a Key Oncogene in Lung Adenocarcinoma.

Anoikis plays an important role in cancer invasion and metastasis. However, the role of anoikis-related genes, AnRGs, in lung adenocarcinoma (LUAD) is not clear. First, anoikis-related genes (AnRGs) were obtained from the Genecard database. Second, the prognostic risk model of AnRGs was established by univariate Cox analysis, the Least Absolute Shrinkage and Selection Operator (LASSO) analysis, and multivariate Cox analysis. Finally, in vitro cell experiments were carried out to determine the expression and function of the key gene AnRGs. Three AnRGs (angiopoietin-like 4, ANGPTL4; Cyclin-Dependent Kinase Inhibitor 3, CDKN3; Solute Carrier Organic Anion Transporter Family Member 1B3, SLCO1B3) were screened for the construction of risk prediction model. Additionally, ANGPTL4 was significantly highly expressed in tumor cells, and the knockdown of ANGPTL4 expression on tumor cells could inhibit tumor cell migration and apoptosis. Constructing a risk model based on anoikis-related genes can effectively differentiate the prognosis of LUAD. ANGPTL4 can be used as a potential new target for LUAD treatment.

Effect of Deletion of ANGPTL4 Gene on Viability, Migration and Invasion Ability and Apoptosis of Hepatocellular Carcinoma Cells.

BACKGROUND: Hepatocellular carcinoma (HCC) is a malignant tumor that impacts individuals worldwide and is particularly prevalent in Asia. Angiopoietin-like protein 4 (ANGPTL4) plays an important role in regulating glucose and lipid metabolism in mouse liver. We sought to explore the effects of the ANGPTL4 gene on cell viability, migration, invasive capacity, and apoptosis of HCC cells. METHODS: The expression of ANGPTL4 in HCC and paracancerous tissues was determined by immunohistochemistry and immunofluorescence assays. The ANGPTL4 knockdown cells were established by shRNA transfection. The effect of ANGPTL4 knockdown on HepG2 and Huh7 cells was determined by Cell Count Kit-8 (CCK-8), wound healing and transwell assays. Cell apoptosis was determined by flow cytometry. RESULTS: The ANGPTL4 expression was dramatically enhanced in HCC tissues than in paracancerous tissues (p < 0.001). HCC cell lines HepG2 and Huh7 with knockdown of ANGPTL4 gene showed lower cell viability, migration, and invasion ability while inducing higher apoptosis levels than the control group (p < 0.001). CONCLUSIONS: High expression of ANGPTL4 is closely related to HCC. Knockdown of ANGPTL4 significantly inhibits the proliferation of HCC cells. This study provides a rationale for the ANGPTL4 gene, a molecular marker of HCC.

ANGPTL4 accelerates ovarian serous cystadenocarcinoma carcinogenesis and angiogenesis in the tumor microenvironment by activating the JAK2/STAT3 pathway and interacting with ESM1.

BACKGROUND: Ovarian cancer (OC) is a malignant neoplasm that displays increased vascularization. Angiopoietin-like 4 (ANGPTL4) is a secreted glycoprotein that functions as a regulator of cell metabolism and angiogenesis and plays a critical role in tumorigenesis. However, the precise role of ANGPTL4 in the OC microenvironment, particularly its involvement in angiogenesis, has not been fully elucidated. METHODS: The expression of ANGPTL4 was confirmed by bioinformatics and IHC in OC. The potential molecular mechanism of ANGPTL4 was measured by RNA-sequence. We used a series of molecular biological experiments to measure the ANGPTL4-JAK2-STAT3 and ANGPTL4-ESM1 axis in OC progression, including MTT, EdU, wound healing, transwell, xenograft model, oil red O staining, chick chorioallantoic membrane assay and zebrafish model. Moreover, the molecular mechanisms were confirmed by Western blot, Co-IP and molecular docking. RESULTS: Our study demonstrates a significant upregulation of ANGPTL4 in OC specimens and its strong association with unfavorable prognosis. RNA-seq analysis affirms that ANGPTL4 facilitates OC development by driving JAK2-STAT3 signaling pathway activation. The interaction between ANGPTL4 and ESM1 promotes ANGPTL4 binding to lipoprotein lipase (LPL), thereby resulting in reprogrammed lipid metabolism and the promotion of OC cell proliferation, migration, and invasion. In the OC microenvironment, ESM1 may interfere with the binding of ANGPTL4 to integrin and vascular-endothelial cadherin (VE-Cad), which leads to stabilization of vascular integrity and ultimately promotes angiogenesis. CONCLUSION: Our findings underscore that ANGPTL4 promotes OC development via JAK signaling and induces angiogenesis in the tumor microenvironment through its interaction with ESM1.

The association between plasma angiopoietin-like protein 4, glucose and lipid metabolism during pregnancy, placental function, and risk of delivering large-for-gestational-age neonates.

BACKGROUND: Large-for-gestational-age (LGA) neonates have increased risk of adverse pregnancy outcomes and adult metabolic diseases. We aimed to investigate the relationship between plasma angiopoietin-like protein 4 (ANGPTL4), a protein involved in lipid and glucose metabolism during pregnancy, placental function, growth factors, and the risk of LGA. METHODS: We conducted a prospective cohort study and recruited women with singleton pregnancies at the National Taiwan University Hospital between 2013 and 2018. First trimester maternal plasma ANGPTL4 concentrations were measured. RESULTS: Among 353 pregnant women recruited, the LGA group had higher first trimester plasma ANGPTL4 concentrations than the appropriate-for-gestational-age group. Plasma ANGPTL4 was associated with hemoglobin A1c, post-load plasma glucose, plasma triglyceride, plasma free fatty acid concentrations, plasma growth hormone variant (GH-V), and birth weight, but was not associated with cord blood growth factors. After adjusting for age, body mass index, hemoglobin A1c, and plasma triglyceride concentrations, plasma ANGPTL4 concentrations were significantly associated with LGA risk, and its predictive performance, as measured by the area under the receiver operating characteristic curve, outperformed traditional risk factors for LGA. CONCLUSIONS: Plasma ANGPTL4 is associated with glucose and lipid metabolism during pregnancy, plasma GH-V, and birth weight, and is an early biomarker for predicting the risk of LGA.

Correlation of serum VEGF-C, ANGPTL4, and activin A levels with frailty.

BACKGROUND: Secretory factors linked to lymphogenesis, such as vascular endothelial growth factor C (VEGF-C), angiopoietin like protein 4 (ANGPTL4), and activin A (ACV-A), have been recognized as potential markers of chronic inflammatory status and age-related diseases. Furthermore, these factors may also be linked to frailty. The primary objective of this study was to examine the serum VEGF-C, ANGPTL4, and ACV-A levels in young individuals, healthy older individuals, and older individuals with pre-frailty and frailty, and to determine their association with pro-inflammatory factor levels. METHODS: We conducted an observational study, enrolling a total of 210 older individuals and 20 young healthy volunteers. Participants were divided into four groups based on the Freid frailty phenotype: healthy young group, older patients without frailty group, pre-frail older group, and frail older group. Plasma and peripheral blood mononuclear cells (PBMCs) were collected from all four groups. ELISA was used to measure the serum levels of VEGF-C, ANGPTL4, ACV-A, and pro-inflammatory cytokines, while RT-qPCR was used to measure the transcription level of VEGF-C, ANGPTL4 and ACV-A in PBMCs. RESULTS: In comparison to healthy young individuals and older participants without frailty, older participants with frailty exhibited lower renal function, higher serum levels and transcription levels of VEGF-C, ANGPTL4, ACV-A, and elevated levels of pro-inflammatory cytokines (CRP, IL-1ß, and TNF-α). Multiple linear regression analysis revealed that serum levels of VEGF-C, ANGPTL4, and ACV-A were positively correlated with the frailty index, independent of age, eGFR, and comorbidities. Furthermore, the receiver operating characteristic (ROC) curve analysis demonstrated that serum levels of VEGF-C, ANGPTL4, and ACV-A have great accuracy in predicting frailty. CONCLUSION: Elevated serum levels of VEGF-C, ANGPTL4, and ACV-A are associated with frailty status.

PPARß/δ-ANGPTL4 axis mediates the promotion of mono-2-ethylhexyl phthalic acid on MYCN-amplified neuroblastoma development.

Di-2-ethylhexyl phthalic acid (DEHP) is one of the most widely used plasticizers in the industry, which can improve the flexibility and durability of plastics. It is prone to migrate from various daily plastic products through wear and leaching into the surrounding environment and decompose into the more toxic metabolite mono-2-ethylhexyl phthalic acid (MEHP) after entering the human body. However, the impacts and mechanisms of MEHP on neuroblastoma are unclear. We exposed MYCN-amplified neuroblastoma SK-N-BE(2)C cells to an environmentally related concentration of MEHP and found that MEHP increased the proliferation and migration ability of tumor cells. The peroxisome proliferator-activated receptor (PPAR) ß/δ pathway was identified as a pivotal signaling pathway in neuroblastoma, mediating the effects of MEHP through transcriptional sequencing analysis. Because MEHP can bind to the PPARß/δ protein and initiate the expression of the downstream gene angiopoietin-like 4 (ANGPTL4), the PPARß/δ-specific agonist GW501516 and antagonist GSK3787, the recombinant human ANGPTL4 protein, and the knockdown of gene expression confirmed the regulation of the PPARß/δ-ANGPTL4 axis on the malignant phenotype of neuroblastoma. Based on the critical role of PPARß/δ and ANGPTL4 in the metabolic process, a non-targeted metabolomics analysis revealed that MEHP altered multiple metabolic pathways, particularly lipid metabolites involving fatty acyls, glycerophospholipids, and sterol lipids, which may also be potential factors promoting tumor progression. We have demonstrated for the first time that MEHP can target binding to PPARß/δ and affect the progression of neuroblastoma by activating the PPARß/δ-ANGPTL4 axis. This mechanism confirms the health risks of plasticizers as tumor promoters and provides new data support for targeted prevention and treatment of neuroblastoma.

Effects of exercise training on ANGPTL3/8 and ANGPTL4/8 and their associations with cardiometabolic traits.

Angiopoietin-like protein (ANGPTL) complexes 3/8 and 4/8 are established inhibitors of LPL and novel therapeutic targets for dyslipidemia. However, the effects of regular exercise on ANGPTL3/8 and ANGPTL4/8 are unknown. We characterized ANGPTL3/8 and ANGPTL4/8 and their relationship with in vivo measurements of lipase activities and cardiometabolic traits before and after a 5-month endurance exercise training intervention in 642 adults from the HERITAGE (HEalth, RIsk factors, exercise Training And GEnetics) Family Study. At baseline, higher levels of both ANGPTL3/8 and ANGPTL4/8 were associated with a worse lipid, lipoprotein, and cardiometabolic profile, with only ANGPTL3/8 associated with postheparin LPL and HL activities. ANGPTL3/8 significantly decreased with exercise training, which corresponded with increases in LPL activity and decreases in HL activity, plasma triglycerides, apoB, visceral fat, and fasting insulin (all P < 5.1 × 10-4). Exercise-induced changes in ANGPTL4/8 were directly correlated to concomitant changes in total cholesterol, LDL-C, apoB, and HDL-triglycerides and inversely related to change in insulin sensitivity index (all P < 7.0 × 10-4). In conclusion, exercise-induced decreases in ANGPTL3/8 and ANGPTL4/8 were related to concomitant improvements in lipase activity, lipid profile, and cardiometabolic risk factors. These findings reveal the ANGPTL3-4-8 model as a potential molecular mechanism contributing to adaptations in lipid metabolism in response to exercise training.

Suppression of angiopoietin-like 4 reprograms endothelial cell metabolism and inhibits angiogenesis.

Angiopoietin-like 4 (ANGPTL4) is known to regulate various cellular and systemic functions. However, its cell-specific role in endothelial cells (ECs) function and metabolic homeostasis remains to be elucidated. Here, using endothelial-specific Angptl4 knock-out mice (Angptl4iΔEC), and transcriptomics and metabolic flux analysis, we demonstrate that ANGPTL4 is required for maintaining EC metabolic function vital for vascular permeability and angiogenesis. Knockdown of ANGPTL4 in ECs promotes lipase-mediated lipoprotein lipolysis, which results in increased fatty acid (FA) uptake and oxidation. This is also paralleled by a decrease in proper glucose utilization for angiogenic activation of ECs. Mice with endothelial-specific deletion of Angptl4 showed decreased pathological neovascularization with stable vessel structures characterized by increased pericyte coverage and reduced permeability. Together, our study denotes the role of endothelial-ANGPTL4 in regulating cellular metabolism and angiogenic functions of EC.

Serum ANGPTL4 and SIRT1 factor levels and the Carotid Atherosclerotic plaque stability relationship analysis.

This study was to investigate the relationship between the levels of Angiopoietin-Like Protein 4 (ANGPTL4) and Silent Mating-type Information Regulation 2 Homolog 1 (SIRT1) and the stability of carotid atherosclerotic plaque. For this purpose, 108 patients with coronary heart disease in our hospital from Jan 2021 to May 2022 were selected as the coronary heart disease (CHD) group and 80 patients with the healthy examination as the control group. Patients' serum levels of ANGPTL4 and SIRT1 were collected, and their stability of carotid atherosclerotic plaque was determined by carotid ultrasound. According to their stability results, patients were divided into three subgroups: No plaque, Stable plaque, and Unstable plaque. The serum ANGPTL4 and SIRT1 levels were analyzed in different groups, and the correlation between their serum levels and the stability of carotid atherosclerotic plaque was analyzed by rank correlation. Results showed that the CHD group's serum ANGPTL4 and SIRT1 levels were lower, with statistical significance (P<0.05); A statistically significant difference in serum ANGPTL4 and SIRT1 levels were observed among patients with No plaques, Stable plaques, and Unstable plaques (P<0.05); A negative correlation was observed between serum levels of ANGPTL4 and SIRT1 and the stability of carotid atherosclerotic plaque (r=-0.438, -0.717, P<0.001); Serum ANGPTL4 and SIRT1 can be used as the evaluation method of carotid atherosclerotic plaque stability. When ANGPTL4 ≤ 30.17mg/L and SIRT1 ≤ 6.91µg/L, patients were more likely to develop unstable plaques; When ANGPTL4 ≤ 30.40mg/L and SIRT1 ≤ 6.87µg/L, patients were more likely to develop plaques (instability and/or stability). In conclusion, the serum levels of ANGPTL4 and SIRT1 in patients with CHD decreased. ANGPTL4 and SIRT1 will participate in the formation and development of carotid plaque, which can be used as a serological evaluation index to evaluate the occurrence and carotid atherosclerotic plaque's stability.

angptl4 gene expression as a marker of adaptive homeostatic response to social isolation across the lifespan in zebrafish.

Social isolation has detrimental health effects, but the underlying mechanisms are unclear. Here, we investigated the impact of 2 weeks of isolation on behavior and gene expression in the central nervous system at different life stages of zebrafish. Results showed that socially deprived young adult zebrafish experienced increased anxiety, accompanied by changes in gene expression. Most gene expression patterns returned to normal within 24 hours of reintroduction to a social environment, except angptl4, which was upregulated after reintroduction, suggesting an adaptive mechanism. Similarly, aging zebrafish displayed heightened anxiety and increased central nervous system expression of angptl4 during isolation, but effects were reversed upon reintroduction to a social group. The findings imply that angptl4 plays a homeostatic role in response to social isolation, which varies across the lifespan. The study emphasizes the importance of social interactions for psychological well-being and highlights the negative consequences of isolation, especially in older individuals. Further research may unravel how social isolation affects angptl4 expression and its developmental and aging effects.

Dual role of ANGPTL4 in inflammation.

BACKGROUND: Angiopoietin-like 4 (ANGPTL4) belongs to the angiopoietin-like protein family and mediates the inhibition of lipoprotein lipase activity. Emerging evidence suggests that ANGPTL4 has pleiotropic functions with anti- and pro-inflammatory properties. METHODS: A thorough search on PubMed related to ANGPTL4 and inflammation was performed. RESULTS: Genetic inactivation of ANGPTL4 can significantly reduce the risk of developing coronary artery disease and diabetes. However, antibodies against ANGPTL4 result in several undesirable effects in mice or monkeys, such as lymphadenopathy and ascites. Based on the research progress on ANGPTL4, we systematically discussed the dual role of ANGPTL4 in inflammation and inflammatory diseases (lung injury, pancreatitis, heart diseases, gastrointestinal diseases, skin diseases, metabolism, periodontitis, and osteolytic diseases). This may be attributed to several factors, including post-translational modification, cleavage and oligomerization, and subcellular localization. CONCLUSION: Understanding the potential underlying mechanisms of ANGPTL4 in inflammation in different tissues and diseases will aid in drug discovery and treatment development.

HIF-1α regulates osteoclastogenesis and alveolar bone resorption in periodontitis via ANGPTL4.

OBJECTIVE: The mechanism of alveolar bone resorption caused by periodontitis is not fully understood. We sought to investigate whether microenvironmental changes of local hypoxia are involved in these processes. METHODS: In this study, periodontitis models of control mice and knockout of Hypoxia Induced Factor 1α (HIF-1α) harboring Cathepsin K (CTSK) Cre mice were constructed to study the effect of osteoclasts affected by hypoxic environment on alveolar bone resorption. RAW264.7 cells were subsequently induced by CoCl2 to observe the effects of HIF-1α and Angiopoietin-like Protein 4 (ANGPTL4) on osteoblast differentiation and fusion. RESULTS: The degree of alveolar bone resorption in the periodontitis tissues was lesser in mice with conditional knockout of HIF-1α in osteoclasts than in wild-type mice. We also observed that HIF-1α conditional knockout mice had fewer osteoclasts on the alveolar bone surface than control mice. HIF-1α increases the expression of ANGPTL4 and promotes the differentiation of RAW264.7 cells into osteoblasts and cell fusion under chemically simulated hypoxic conditions. CONCLUSION: HIF-1α regulates osteoclastogenesis and participates in bone resorption in periodontitis through ANGPTL4.

Transcriptomic and functional analysis of ANGPTL4 overexpression in pancreatic cancer nominates targets that reverse chemoresistance.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers based on five-year survival rates. Genes contributing to chemoresistance represent novel therapeutic targets that can improve treatment response. Increased expression of ANGPTL4 in tumors correlates with poor outcomes in pancreatic cancer. METHODS: We used statistical analysis of publicly available gene expression data (TCGA-PAAD) to test whether expression of ANGPTL4 and its downstream targets, ITGB4 and APOL1, were correlated with patient survival. We measured the impact of ANGPTL4 overexpression in a common pancreatic cancer cell line, MIA PaCa-2 cells, using CRISPRa for overexpression and DsiRNA for knockdown. We characterized global gene expression changes associated with high levels of ANGPTL4 and response to gemcitabine treatment using RNA-sequencing. Gemcitabine dose response curves were calculated on modified cell lines by measuring cell viability with CellTiter-Glo (Promega). Impacts on cell migration were measured using a time course scratch assay. RESULTS: We show that ANGPTL4 overexpression leads to in vitro resistance to gemcitabine and reduced survival times in patients. Overexpression of ANGPTL4 induces transcriptional signatures of tumor invasion and metastasis, proliferation and differentiation, and inhibition of apoptosis. Analyses revealed an overlapping signature of genes associated with both ANGPTL4 activation and gemcitabine response. Increased expression of the genes in this signature in patient PDAC tissues was significantly associated with shorter patient survival. We identified 42 genes that were both co-regulated with ANGPTL4 and were responsive to gemcitabine treatment. ITGB4 and APOL1 were among these genes. Knockdown of either of these genes in cell lines overexpressing ANGPTL4 reversed the observed gemcitabine resistance and inhibited cellular migration associated with epithelial to mesenchymal transition (EMT) and ANGPTL4 overexpression. CONCLUSIONS: These data suggest that ANGPTL4 promotes EMT and regulates the genes APOL1 and ITGB4. Importantly, we show that inhibition of both targets reverses chemoresistance and decreases migratory potential. Our findings have revealed a novel pathway regulating tumor response to treatment and suggest relevant therapeutic targets in pancreatic cancer.

[Effects of Peroxisome Proliferator-Activated Receptor γ on Modulating Angiopoietin-Like Protein 4 Synthesis in Caco-2 Cells Exposed to Clostridium butyricum].

Angiopoietin-like protein 4 (ANGPTL4) is considered to be one of the important circulating mediators linking intestinal microorganisms and host lipid metabolism. The objective of this study was to assess the effects of peroxisome proliferator-activated receptor у (PPARγ) on modulating ANGPTL4 synthesis in Caco-2 cells exposed to Clostridium butyricum. The viability of Caco-2 cells and the expression of PPARγ and ANGPTL4 in Caco-2 cells were detected after the Caco-2 cells were co-cultured with C. butyricum at the concentration of 1 x 10^(6), 1 x 10^(7) and 1 x 10^(8) CFU/mL. The results showed that cell viability was enhanced by C. butyricum. Besides, PPARγ and ANGPTL4 expression and secretion in Caco-2 cells was significantly increased by 1 x 10^(7) and 1 x 10^(8) CFU/mL of C. butyricum. Furthermore, the effects of PPARγ on modulating ANGPTL4 synthesis in Caco-2 cells regulated by 1 x 10^(8) CFU/mL of C. butyricum was also be expounded in PPARγ activation/inhibition model based on Caco-2 cells and via ChIP technique. It was found that C. butyricum promoted the binding of PPARγ to the PPAR binding site (chr19: 8362157-8362357, located upstream of the transcriptional start site of angptl4) of the angptl4 gene in Caco-2 cells. However, the PPARγ was not the only way for C. butyricum to stimulate ANGPTL4 production. Taken together, PPARγ played a role in the regulation of ANGPTL4 synthesis by C. butyricum in Caco-2 cells.