Endothelial Lipase Research Articles

Functionally overlapping intra- and extralysosomalpathways promote bis(monoacylglycero)phosphate synthesis in mammalian cells.

Bis(monoacylglycero)phosphate (BMP) is a major phospholipid constituent of intralumenal membranes in late endosomes/lysosomes, where it regulates the degradation and sorting of lipid cargo. Recent observations suggest that the Batten disease-associated protein CLN5 functions as lysosomal BMP synthase. Here, we show that transacylation reactions catalyzed by cytosolic and secreted enzymes enhance BMP synthesis independently of CLN5. The transacylases identified in this study are capable of acylating the precursor lipid phosphatidylglycerol (PG), generating acyl-PG, which is subsequently hydrolyzed to BMP. Extracellularly, acyl-PG and BMP are generated by endothelial lipase in cooperation with other serum enzymes of the pancreatic lipase family. The intracellular acylation of PG is catalyzed by several members of the cytosolic phospholipase A2 group IV (PLA2G4) family. Overexpression of secreted or cytosolic transacylases was sufficient to correct BMP deficiency in HEK293 cells lacking CLN5. Collectively, our observations suggest that functionally overlapping pathways promote BMP synthesis in mammalian cells.

Angioprotein-like 3 and atheroma progression in statin-treated type 2 diabetic patients with coronary artery disease: the pre-specified analysis from the OPTIMAL randomized controlled trial

Abstract Introduction Despite guideline-recommended control of LDL-C with a statin, type 2 diabetic patients more likely cause cardiovascular events. This indicates the need to identify additional therapeutic targets in those patients. Angioprotein-like 3 (ANGPTL3) is an inhibitor of lipoprotein and endothelial lipase, which increases the levels of LDL-C and other atherogenic lipoproteins. These properties suggest ANGPTL3 as a potential driver associated with diabetic atherosclerosis. The OPTIMAL randomized controlled trial (jRCT1052180152) compared the efficacy of continuous glucose monitoring-guided versus HbA1c-guided glycemic control on coronary atherosclerosis in statin-treated type 2 diabetic patients by using serial intravascular ultrasound (IVUS) imaging. This pre-specified analysis of the OPTIMAL study was designed to evaluate whether ANGPTL3 affects progression of coronary atheroma in statin-treated type 2 diabetic patients. Purpose To elucidate the association of serial change in ANGPTL3 with the degree of atheroma progression in statin-treated type 2 diabetic patients. Methods 59 patients (59 lesions) with serial ANGPTL3 levels at baseline and week 48 were included into the current analysis. Clinical demographics and IVUS-derived measure were compared in patients with and without any increase in ANGPTL3. Results All of study subjects received a statin, and over 60% of them were treated with high-intensity statin. Under these lipid-lowering therapies, any increase in ANGPTL3 levels at week 48 was observed in 52.5% of study participants. Patients with any increase in ANGPTL3 were more likely to have a history of hypertension (90.0% vs. 64.3%, p=0.02), whereas there was no significant difference in on-treatment LDL-C levels between the two groups (1.8 ± 0.4 vs. 1.6 ± 0.6 mmol/L, p=0.25) (Table). On IVUS imaging analysis, baseline percent atheroma volume (PAV) did not differ in those with and without any increase in ANGPTL3. However, patients with any increase in ANGPTL3 presented a greater progression of PAV (0.08 ± 0.28 vs. -0.74 ± 0.29, p=0.04). There was a trend toward a lower frequency of PAV regression in those exhibiting any increase in ANGPTL3 (48.4% vs. 57.1%), but this comparison did not meet statistical significance (p=0.50) (Figure). Multivariate analysis adjusting clinical characteristics demonstrated that any increase in ANGPTL3 level was not independently associated with PAV progression (β=0.16, 95%CI=-0.01 – 0.18, p=0.27). Conclusion Over 50% of statin-treated type 2 diabetic patients with coronary atherosclerosis showed any increase in ANGPTL3 levels at week 48. Serial IVUS imaging revealed that patients with any increase in ANGPTL3 more likely presented a greater atheroma progression. However, this relationship did not exist after adjusting clinical characteristics. Our findings suggest that ANGPTL3 may not be a pivotal driver associated with atheroma progression in statin-treated type 2 diabetic patients.

ANGPTL4-the Link Binding Lipid Metabolism and Inflammation.

Angiopoietin-like 4 (ANGPTL4) belongs to the family of angiopoietin- like proteins. The involvement of ANGPTL4 in various aspects of lipid metabolism and inflammation has become an important area of research. A thorough search on PubMed related to ANGPTL4, lipid metabolism, and inflammation was performed. Over the past two decades, the recognition of ANGPTL4 as a potent regulator of lipid metabolism has substantially increased. As part of the senescence-associated secretory phenotype, ANGPTL4 also serves as an inflammatory mediator. Considering the advancements in ANGPTL4 research, we have highlighted that ANGPTL4 acts as a key node linking lipid metabolism and inflammation. ANGPTL4 impacts inflammation by regulating lipid metabolism. It affects critical enzymes (lipoprotein lipase, hepatic lipase, endothelial lipase, and acetyl-CoA carboxylase), regulatory factors (AMPK, cAMP, SLC7A11, GPX4, and mTOR), and receptors (LepR, CD36, and PPARγ) of lipid oxidation, synthesis, and peroxidation, thereby affecting immune cells and inflammatory pathways. Understanding the potential association and the therapeutic value of ANGPTL4 for regulating lipid metabolism and inflammation could contribute to drug discovery and therapeutic development.

Abstract P153: The Role of Lipoprotein Lipase Activation in Vascular Aging

Lipoprotein metabolism plays a role in cardiovascular diseases and becomes impaired with aging. Angiopoietin-like proteins (ANGPTLs) regulate lipoprotein lipase (LPL) and endothelial lipase (EL), key hydrolases in triglyceride catabolism. We hypothesized that ANGPTL3 and ANGPTL4 would be elevated in aging and that the response to LPL activation would be impaired in mesenteric resistance arteries (MRAs) from old rats. To assess this, MRAs were isolated from 3 and 16-month-old male and female Fischer344 rats and mounted on wire myographs. Concentration-response curves (CRC) to phenylephrine (PE, 10nM-100μM), Ca 2+ channel agonist Bay-K8644 (10nM-30nM), and acetylcholine (ACh, 0.1nM-100uM) were performed with or without LPL activator, NO-1886 (10uM and 50uM). Protein expression was assessed by Western blot. We show for the first time that circulating ANGPTL3 (young: 1.5±0.8 vs old: 5±0.7) and ANGPTL4 (young: 1.7±0.3 vs old: 2.5±0.5) are increased in aging. In MRAs from young rats, NO-1886 attenuated PE-induced contraction in males (Emax; vehicle: 106±3 vs NO-1886 10uM: 86 ± 5* vs NO-1886 50uM: 69±8*, p<0.05) and females (Emax; vehicle: 104±4 vs NO-1886 10uM: 91±5* vs NO-1886 50uM: 75±8*, p<0.05). While 16-month-old males presented a similar reduction in contraction (Emax; vehicle: 105±6 vs NO-1886 10uM: 88±11* vs NO-1886 50uM: 73±17*, p<0.05), in females only 50uM showed a significant anti-contractile effect in a sex-dependent manner (Emax; vehicle: 100±7 vs NO-1886 10uM: 95±7 vs NO-1886 50uM: 83±22*, p<0.05). CRC to bay-K8644 showed decreased contraction after NO-1886 incubation (Emax; vehicle: 16±8 vs NO-1886 50uM: 5±3) indicating that L-type Ca 2+ channel Ca 2+ influx isn’t involved in NO-1886’s anti-contractile effect. NO-1886 incubation did not change the maximal ACh response in young rat MRAs, but a rightward shift in the curve was seen in both sexes. As expected, MRAs from old males (Emax; young: 97±2 vs old: 86±7) and females (Emax; young: 95±2 vs old: 92±6) had decreased maximal relaxation to ACh, compared to young rats. Interestingly, in old rats NO-1886 induced further impaired relaxation to ACh in males (Emax; vehicle: 86±7 vs NO-1886 10uM: 78±14) and females (Emax; vehicle: 92±6 vs NO-1886 10uM: 77±22). Together, this data suggests (1) ANGPTL3 and ANGPTL4 are increased in old rats, (2) LPL/EL activity diminished with age in females, but not males, and (3) while NO-1886 exerts an anti-contractile effect, it can also induce endothelial dysfunction.

Endothelial lipase and its endogenous inhibitor angiopoietin-like protein 3 regulate the transport of both low- and high- density lipoproteins by aortic endothelial cells

Endothelial lipase and its endogenous inhibitor angiopoietin-like protein 3 regulate the transport of both low- and high- density lipoproteins by aortic endothelial cells

ANGPTL3 regulates the peroxisomal translocation of SmarcAL1 in response to cell growth states.

Angiopoietin-like 3 (ANGPTL3) is a key regulator of lipoprotein metabolism, known for its potent inhibition on intravascular lipoprotein and endothelial lipase activities. Recent studies have shed light on the cellular functions of ANGPTL3. However, the precise mechanism underlying its regulation of cellular lipid metabolism remains elusive. We recently reported that ANGPTL3 interacts with the chromatin regulator SMARCAL1, which plays a pivotal role in maintaining cellular lipid homeostasis. Here, through a combination of in vitro and in vivo functional analyses, we provide evidence that ANGPTL3 indeed influences cellular lipid metabolism. Increased expression of Angptl3 prompted the formation of lipid droplets (LDs) in response to slow growth conditions. Notably, under the conditions, Angptl3 accumulated within cytoplasmic peroxisomes, where it interacts with SmarcAL1, which translocated from nucleus as observed previously. This translocation induced changes in gene expression favoring triglyceride (TG) accumulation. Indeed, ANGPTL3 gene knockout (KO) in human cells increased the expression of key lipid genes, which could be linked to elevated nuclear localization of SMARCAL1, whereas the expression of these genes decreased in SMARCAL1 KO cells. Consistent with these findings, the injection of Angptl3 protein to mice led to hepatic fat accumulation derived from circulating blood, a phenotype likely indicative of its long-term effect on blood TG, linked to SmarcAL1 activities. Thus, our results suggest that the Angptl3-SmarcAL1 pathway may confer the capacity for TG storage in cells in response to varying growth states, which may have broad implications for this pathway in regulating energy storage and trafficking.

Evinacumab: Mechanism of action, clinical, and translational science

AbstractHomozygous familial hypercholesterolemia (HoFH) is a rare and serious genetic condition characterized by premature cardiovascular disease due to severely elevated low‐density lipoprotein cholesterol (LDL‐C). HoFH primarily results from loss‐of‐function (LOF) mutations in the LDL receptor (LDLR), reducing LDL‐C clearance such that patients experience severe hypercholesterolemia, exacerbating the risk of developing cardiovascular events. Treatment options such as statins, lomitapide, ezetimibe, proprotein convertase subtilisin/kexin type 9 inhibitors, and apheresis help lower LDL‐C; however, many patients with HoFH still fail to reach their target LDL‐C levels and many of these lipid‐lowering therapies are not indicated for pediatric use. Angiopoietin‐like protein 3 (ANGPTL3) has been identified as a target to treat elevated LDL‐C by acting as a natural inhibitor of lipoprotein lipase (LPL) and endothelial lipase (EL), enzymes involved in the hydrolysis of the triglyceride and phospholipid content of very low‐density lipoproteins. Persons heterozygous for LOF mutations in ANGPTL3 were reported to have lower LDL‐C than non‐carriers and lower risk of coronary artery disease. Evinacumab is a first‐in‐class human monoclonal antibody that specifically binds to ANGPTL3 to prevent its inhibition of LPL and EL. In clinical trials, a 15 mg/kg intravenous dose every 4 weeks has shown a mean percent change from baseline in LDL‐C of ~50% in adult, adolescent, and pediatric patients with HoFH. This mini review article describes the mechanism of action of evinacumab, evinacumab population PK and PD modeling, and clinical development history of evinacumab for the treatment of HoFH.

Circumventing Cardiovascular Calamities: The Dawn of ANGPTL3 Blockade in Severe Dyslipidemia Management.

The landscape of severe dyslipidemia treatment is undergoing a remarkable transformation with the advent of angiopoietin-like 3 (ANGPTL3) inhibitors. ANGPTL3, a pivotal regulator of lipoprotein lipase and endothelial lipase, orchestrates the catabolism of triglyceride-rich and high-density lipoproteins, thus playing a critical role in lipid homeostasis. This review article examines the therapeutic potential of ANGPTL3 blockade and its implications for patients with severe dyslipidemias, particularly those unresponsive to traditional lipid-lowering regimens. We delve into the molecular mechanisms by which ANGPTL3 influences lipid metabolism and appraise the clinical utility of emerging therapeutics, such as monoclonal antibodies and antisense oligonucleotides. Moreover, we discuss the impact of ANGPTL3 inhibition on cardiovascular risk factors and project its promising role in reducing cardiovascular morbidity and mortality. The narrative synthesizes data from recent clinical trials, including the efficacy and safety profiles of ANGPTL3 inhibitors, and forecasts the potential of these agents to revolutionize the management of dyslipidemic conditions. The advent of ANGPTL3-targeted therapies signifies a potential breakthrough in the therapeutic armamentarium against complex lipid disorders, heralding a new era of precision medicine in cardiovascular risk mitigation.

Zodasiran, an RNAi Therapeutic Targeting ANGPTL3, for Mixed Hyperlipidemia

BackgroundAngiopoietin-like 3 (ANGPTL3) inhibits lipoprotein and endothelial lipases and hepatic uptake of triglyceride-rich lipoprotein remnants. ANGPTL3 loss-of-function carriers have lower levels of triglycerides, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and non-HDL cholesterol and a lower risk of atherosclerotic cardiovascular disease than noncarriers. Zodasiran is an RNA interference (RNAi) therapy targeting expression of ANGPTL3 in the liver.MethodsWe conducted a double-blind, placebo-controlled, dose-ranging phase 2b trial to evaluate the safety and efficacy of zodasiran in adults with mixed hyperlipidemia (fasting triglyceride level of 150 to 499 mg per deciliter and either an LDL cholesterol level of ≥70 mg per deciliter or a non-HDL cholesterol level of ≥100 mg per deciliter). Eligible patients were randomly assigned in a 3:1 ratio to receive subcutaneous injections of zodasiran (50, 100, or 200 mg) or placebo on day 1 and week 12 and were followed through week 36. The primary end point was the percent change in the triglyceride level from baseline to week 24.ResultsA total of 204 patients underwent randomization. At week 24, substantial mean dose-dependent decreases from baseline in ANGPTL3 levels were observed with zodasiran (difference in change vs. placebo, −54 percentage points with 50 mg, −70 percentage points with 100 mg, and −74 percentage points with 200 mg), and significant dose-dependent decreases in triglyceride levels were observed (difference in change vs. placebo, −51 percentage points, −57 percentage points, and −63 percentage points, respectively) (P<0.001 for all comparisons). Other differences in change from baseline as compared with placebo included the following: for non-HDL cholesterol level, −29 percentage points with 50 mg, −29 percentage points with 100 mg, and −36 percentage points with 200 mg; for apolipoprotein B level, −19 percentage points, −15 percentage points, and −22 percentage points, respectively; and for LDL cholesterol level, −16 percentage points, −14 percentage points, and −20 percentage points, respectively. We observed a transient elevation in glycated hemoglobin levels in patients with preexisting diabetes who received the highest dose of zodasiran.ConclusionsIn patients with mixed hyperlipidemia, zodasiran was associated with significant decreases in triglyceride levels at 24 weeks. (Funded by Arrowhead Pharmaceuticals; ARCHES-2 ClinicalTrials.gov number, NCT04832971.)

Unraveling the metabolic pattern of angiopoietin-like 3 knock-out mouse models under fasting and fed conditions

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): University of Milan Background Angiopoietin-like 3 (ANGPTL3) is a hepatokine and a regulator of lipid and lipoprotein metabolism through lipoprotein lipase and endothelial lipase inhibition, preventing the hydrolyzation of lipoprotein-derived triglycerides. A lack of ANGPTL3 results into a hypolipidemic phenotype, with a lower profile of lipids and lipoproteins, and this is evident in humans carrying a loss of function mutation, or in cellular or in vivo models. ANGPTL3 action, from the liver, is finely regulated between oxidative and storage tissues in the fasting and postprandial phases; from the current pharmacological treatments a possible ANGPTL3 intrahepatic role besides the lipases’ inhibition is emerging, thus possibly affecting the systemic metabolism with different implications. Purpose An axis between ANGPTL3 and other Angiopoietin-like proteins is known to regulate the triglyceride partitioning after a meal or during fasting, however the effect on tissues and the following metabolic and pathologic implications are still not known. Therefore, we aim to describe the impact of ANGPTL3 deficiency in fasting or in a postprandial state, and in different compartments of the organism. Methods As models, we utilized Angptl3 Knock-out (KO) mice (C57BL6/J background) and their littermate controls (wild-type, WT) fed a chow diet for 16 weeks. We assessed the metabolic phenotype with indirect calorimetry and with lipids, glucose, and insulin tolerance tests; we evaluated changes in plasma lipids under fast, fed, and fast-refeed settings and we investigated the histology of key metabolic organs. Results ANGPTL3 KO mice fed ad libitum a chow diet are hypolipidemic (plasma triglycerides levels: 42,42±8,80 mg/dL in ANGPTL3 KO mice vs. 122,02±55,09 mg/dL in WT mice; plasma cholesterol levels: 44,00±9,11 mg/dL in ANGPTL3 KO mice vs. 76,51±15,87 mg/dL in WT mice). The oral charge lipid challenge suggests that KO mice have lower lipid levels at all time points. Conclusions This preliminary profiling of ANGPTL3 KO mice under fasting and fed conditions highlights the hypolipidemia of these models, and the potentially beneficial impact of ANGPTL3 deficiency on their metabolism compared to controls.

Abstract 2046: Overexpression Of Endothelial Lipase Enhances The Cellular Uptake Of Low-density Lipoproteins In Cultured Hepatocytes In The Absence Of Low-density Lipoprotein Receptor.

Background: Inhibitors of angiopoietin-like3 (ANGPTL3) reduce low-density lipoprotein (LDL) cholesterol, even in Familial Hypercholesterolemia (FH) patients with a dysfunctional LDL receptor (LDLR). Although the exact mechanism remains elusive, it may depend upon endothelial lipase (EL). Early studies showed that EL mediates the cellular uptake of high-density lipoproteins in hepatocytes; however, whether EL similarly mediates LDL uptake is unknown. Aim: Investigate the role of EL in mediating the cellular uptake of LDL in an LDLR-deficient model. Methods: Cas9-expressing HepG2 cells were transfected with a scrambled or an LDLR -targeting guide RNA to produce control and LDLR -knockout (KO) cells. Control and KO cells were transfected by lipofection with an empty plasmid or a plasmid containing the human LIPG gene (EL). Cellular uptake of fluorescent human LDL was measured by FACS. In addition, we measured the uptake of LDL in cells with and without the pre-incubation with 5 U/ml heparin or a cocktail of heparinases I, II, and II to test the contribution of heparan sulfate proteoglycans (HSPG). Results: LDLR -KO HepG2 cells showed a 20-25% residual uptake of LDL compared to controls (p&lt;0.001) and 10-fold higher levels of EL mRNA. Remarkably, LIPG -transfected LDLR -KO hepatocytes showed a 2-fold increase in LDL uptake compared to LDLR-KO cells non-overexpressing EL (p&lt;0.001). The pre-incubation with either heparinases or heparin completely blocked the uptake of LDL not only in LIPG -transfected LDLR -KO cells but also in those LDLR -KO cells transfected with the empty plasmid, suggesting a crucial role of HSPG in the LDL uptake. Conversely, overexpression of EL decreased LDL uptake in control cells (-11%, p=0.02), while unchanged or slightly increased LDL uptake was observed after incubating with heparinases or heparin. Conclusions: Our findings demonstrate that EL facilitates the uptake of LDL through an LDLR-independent, HSPG-dependent pathway. This pathway may be responsible for the residual uptake of LDL observed in LDLR -KO hepatocytes and may represent a potential druggable target to treat FH. Our data provides an alternative mechanism to explain the reduction of LDL cholesterol induced by ANGPTL3 inhibitors.

Definition of the metabolic pattern of ANGPTL3 deficient mice on a chow diet and under dysmetabolic conditions

Aim: ANGPTL3 controls lipid and lipoprotein metabolism through lipoprotein lipase and endothelial lipase inhibition and the prevention of lipoprotein-derived triglycerides hydrolyzation. Here we present the metabolic profile of ANGPTL3 deficient mice in physiology and during the development of metabolic disorders. Methods: Angptl3 KO mice (C57BL6/J background) and their littermate controls (wild-type, WT) were fed a chow and a High Fat Diet (HFD, 60%kcal from lipids) for 16 weeks. During the diet protocol, changes in lipids and lipoprotein profile, under fast, fed, and fast-refeed setting were assessed. The metabolic phenotype was assessed, with a Glucose Tolerance Test (GTT) and an Insulin Tolerance Test (ITT); the lipids absorption profile was assessed with an Oral Lipid Tolerance Test (OLTT). Results: ANGPTL3 KO mice fed ad libitum a chow diet are hypolipidemic (plasma triglycerides levels: 42,42±8,80 mg/dL in ANGPTL3 KO mice compared to 122,02±55,09 mg/dL in WT mice; plasma cholesterol levels: 44,00±9,11 mg/dL in ANGPTL3 KO mice compared to 76,51±15,87 mg/dL in WT mice). After 16h fasting, ANGPTL3 KO mice on a chow diet are hypolipidemic and display small lipoproteins less rich in cholesterol and triglycerides, as established in humans, and the same holds true for mice fed a HFD diet. On HFD, ANGPTL3 KO mice gain less body weight, suggesting an improved metabolic profile compared to WT animals. The hypolipidemia is conserved during all the timepoints of OLTT, both in mice on chow or HFD, suggesting a different lipid management; in spite, no significant differences in the circulating glycaemia has been proved with a GTT after 16h of fasting; likewise, a similar sensitivity to insulin has been outlined with an ITT after 4h of fasting. Conclusions: This metabolic profiling of ANGPTL3 KO mice on chow diet or HFD highlights that these mice are hypolipidemic and may have beneficial metabolic features compared to controls.

In Silico Description of the Direct Inhibition Mechanism of Endothelial Lipase by ANGPTL3.

Angiopoietin-like protein 3 (ANGPTL3) is a plasmatic protein that plays a crucial role in lipoprotein metabolism by inhibiting the lipoprotein lipase (LPL) and the endothelial lipase (EL) responsible for the hydrolysis of phospholipids on high-density lipoprotein (HDL). Interest in developing new pharmacological therapies aimed at inhibiting ANGPTL3 has been growing due to the hypolipidemic and antiatherogenic profile observed in its absence. The goal of this study was the in silico characterization of the interaction between ANGPTL3 and EL. Because of the lack of any structural information on both the trimeric coiled-coil N-terminal domain of ANGPTL3 and the EL homodimer as well as data regarding their interactions, the first step was to obtain the three-dimensional model of these two proteins. The models were then refined via molecular dynamics (MD) simulations and used to investigate the interaction mechanism. The analysis of interactions in different docking poses and their refinement via MD allowed the identification of three specific glutamates of ANGPTL3 that recognize a positively charged patch on the surface of EL. These ANGPTL3 key residues, i.e., Glu154, Glu157, and Glu160, could form a putative molecular recognition site for EL. This study paves the way for future investigations aimed at confirming the recognition site and at designing novel inhibitors of ANGPTL3.

Expression of Placental Lipid Transporters in Pregnancies Complicated by Gestational and Type 1 Diabetes Mellitus.

The objective of the study was to assess the expression of proteins responsible for placental lipid transport in term pregnancies complicated by well-controlled gestational (GDM) and type 1 diabetes mellitus (PGDM). A total of 80 placental samples were obtained from patients diagnosed with PGDM (n = 20), GDM treated with diet (GDMG1, n = 20), GDM treated with diet and insulin (GDMG2, n = 20), and a non-diabetic control group (n = 20). Umbilical and uterine artery blood flows were assessed by means of ultrasound in the period prior to delivery and computer-assisted quantitative morphometry of immunostained placental sections was performed to determine the expression of selected proteins. The morphometric analysis performed for the vascular density-matched placental samples demonstrated a significant increase in the expression of fatty acid translocase (CD36), fatty acid binding proteins (FABP1, FABP4 and FABP5), as well as a decrease in the expression of endothelial lipase (EL) and fatty acid transport protein (FATP4) in the PGDM-complicated pregnancies as compared to the GDMG1 and control groups (p < 0.05). No significant differences with regard to the placental expression of lipoprotein lipase (LPL) and FATP6 protein between GDM/PGDM and non-diabetic patients were noted. Maternal pre-pregnancy weight, body mass index, placental weight as well as the expression of LPL and FABP4 were selected by the linear regression model as the strongest contributors to the fetal birth weight. To conclude, in placentas derived from pregnancies complicated by well-controlled PGDM, the expression of several lipid transporters, including EL, CD36, FATP4, FABP1, FABP4 and FABP5, is altered. Nonetheless, only LPL and FABP4 were significant predictors of the fetal birth weight.

ANGPTL3 is a novel HDL component that regulates HDL function

BackgroundAngiopoietin-like protein 3 (ANGPTL3) is secreted by hepatocytes and inhibits lipoprotein lipase and endothelial lipase activity. Previous studies reported the correlation between plasma ANGPTL3 levels and high-density lipoprotein (HDL). Recently ANGPTL3 was found to preferentially bind to HDL in healthy human circulation. Here, we examined whether ANGPTL3, as a component of HDL, modulates HDL function and affects HDL other components in human and mice with non-diabetes or type 2 diabetes mellitus.MethodsHDL was isolated from the plasma of female non-diabetic subjects and type-2 diabetic mellitus (T2DM) patients. Immunoprecipitation, western blot, and ELISA assays were used to examine ANGPTL3 levels in HDL. Db/m and db/db mice, AAV virus mediated ANGPTL3 overexpression and knockdown models and ANGPTL3 knockout mice were used. The cholesterol efflux capacity induced by HDL was analyzed in macrophages preloaded with fluorescent cholesterol. The anti-inflammation capacity of HDL was assessed using flow cytometry to measure VCAM-1 and ICAM-1 expression levels in TNF-α-stimulated endothelial cells pretreated with HDL.ResultsANGPTL3 was found to bind to HDL and be a component of HDL in both non-diabetic subjects and T2DM patients. Flag-ANGPTL3 was found in the HDL of transgenic mice overexpressing Flag-ANGPTL3. ANGPLT3 of HDL was positively associated with cholesterol efflux in female non-diabetic controls (r = 0.4102, p = 0.0117) but not in female T2DM patients (r = − 0.1725, p = 0.3224). Lower ANGPTL3 levels of HDL were found in diabetic (db/db) mice compared to control (db/m) mice and were associated with reduced cholesterol efflux and inhibition of VCAM-1 and ICAM-1 expression in endothelial cells (p < 0.05 for all). Following AAV-mediated ANGPTL3 cDNA transfer in db/db mice, ANGPTL3 levels were found to be increased in HDL, and corresponded to increased cholesterol efflux and decreased ICAM-1 expression. In contrast, knockdown of ANGPTL3 levels in HDL by AAV-mediated shRNA transfer led to a reduction in HDL function (p < 0.05 for both). Plasma total cholesterol, total triglycerides, HDL-c, protein components of HDL and the cholesterol efflux function of HDL were lower in ANGPTL3−/− mice than ANGPTL3+/+ mice, suggesting that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL.ConclusionANGPTL3 was identified as a component of HDL in humans and mice. ANGPTL3 of HDL regulated cholesterol efflux and the anti-inflammatory functions of HDL in T2DM mice. Both the protein components of HDL and cholesterol efflux capacity of HDL were decreased in ANGPTL3−/− mice. Our findings suggest that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL. Our study contributes to a more comprehensive understanding of the role of ANGPTL3 in lipid metabolism.

Endothelial lipase variant T111I does not alter inhibition by angiopoietin-like proteins

High levels of HDL-C are correlated with a decreased risk of cardiovascular disease. HDL-C levels are modulated in part by the secreted phospholipase, endothelial lipase (EL), which hydrolyzes the phospholipids of HDL and decreases circulating HDL-C concentrations. A 584C/T polymorphism in LIPG, the gene which encodes EL, was first identified in individuals with increased HDL levels. This polymorphism results in a T111I point mutation the EL protein. The association between this variant, HDL levels, and the risk of coronary artery disease (CAD) in humans has been extensively studied, but the findings have been inconsistent. In this study, we took a biochemical approach, investigating how the T111I variant affected EL activity, structure, and stability. Moreover, we tested whether the T111I variant altered the inhibition of phospholipase activity by angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4), two known EL inhibitors. We found that neither the stability nor enzymatic activity of EL was altered by the T111I variant. Moreover, we found no difference between wild-type and T111I EL in their ability to be inhibited by ANGPTL proteins. These data suggest that any effect this variant may have on HDL-C levels or cardiovascular disease are not mediated through alterations in these functions.

Cornelian Cherry (Cornus mas L.) Fruit Extract Lowers SREBP-1c and C/EBPα in Liver and Alters Various PPAR-α, PPAR-γ, LXR-α Target Genes in Cholesterol-Rich Diet Rabbit Model.

Cornelian cherry (Cornus mas L.) fruits, abundant in iridoids and anthocyanins, are natural products with proven beneficial impacts on the functions of the cardiovascular system and the liver. This study aims to assess and compare whether and to what extent two different doses of resin-purified cornelian cherry extract (10 mg/kg b.w. or 50 mg/kg b.w.) applied in a cholesterol-rich diet rabbit model affect the levels of sterol regulatory element-binding protein 1c (SREBP-1c) and CCAAT/enhancer binding protein α (C/EBPα), and various liver X receptor-α (LXR-α), peroxisome proliferator-activated receptor-α (PPAR-α), and peroxisome proliferator-activated receptor-γ (PPAR-γ) target genes. Moreover, the aim is to evaluate the resistive index (RI) of common carotid arteries (CCAs) and aortas, and histopathological changes in CCAs. For this purpose, the levels of SREBP-1c, C/EBPα, ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), fatty acid synthase (FAS), endothelial lipase (LIPG), carnitine palmitoyltransferase 1A (CPT1A), and adiponectin receptor 2 (AdipoR2) in liver tissue were measured. Also, the levels of lipoprotein lipase (LPL), visceral adipose tissue-derived serine protease inhibitor (Vaspin), and retinol-binding protein 4 (RBP4) in visceral adipose tissue were measured. The RI of CCAs and aortas, and histopathological changes in CCAs, were indicated. The oral administration of the cornelian cherry extract decreased the SREBP-1c and C/EBPα in both doses. The dose of 10 mg/kg b.w. increased ABCA1 and decreased FAS, CPT1A, and RBP4, and the dose of 50 mg/kg b.w. enhanced ABCG1 and AdipoR2. Mitigations in atheromatous changes in rabbits' CCAs were also observed. The obtained outcomes were compared to the results of our previous works. The beneficial results confirm that cornelian cherry fruit extract may constitute a potentially effective product in the prevention and treatment of obesity-related disorders.

Zinc finger protein ZNF638 regulates triglyceride metabolism via ANGPTL8 in an estrogen dependent manner

Background and aimTriglyceride (TG) levels are closely related to obesity, fatty liver and cardiovascular diseases, while the regulatory factors and mechanism for triglyceride homeostasis are still largely unknown. Zinc Finger Protein 638 (ZNF638) is a newly discovered member of zinc finger protein family for adipocyte function in vitro. The aim of the present work was to investigate the role of ZNF638 in regulating triglyceride metabolism in mice. MethodsWe generated ZNF638 adipose tissue specific knockout mice (ZNF638 FKO) by cross-breeding ZNF638 flox to Adiponectin-Cre mice and achieved adipose tissue ZNF638 overexpression via adenoviral mediated ZNF638 delivery in inguinal adipose tissue (iWAT) to examined the role and mechanisms of ZNF638 in fat biology and whole-body TG homeostasis. ResultsAlthough ZNF638 FKO mice showed similar body weights, body composition, glucose metabolism and serum parameters compared to wild-type mice under chow diet, serum TG levels in ZNF638 FKO mice were increased dramatically after refeeding compared to wild-type mice, accompanied with decreased endothelial lipoprotein lipase (LPL) activity and increased lipid absorption of the small intestine. Conversely, ZNF638 overexpression in iWAT reduced serum TG levels while enhanced LPL activity after refeeding in female C57BL/6J mice and obese ob/ob mice. Specifically, only female mice exhibited altered TG metabolism upon ZNF638 expression changes in fat. Mechanistically, RNA-sequencing analysis revealed that the TG regulator angiopoietin-like protein 8 (Angptl8) was highly expressed in iWAT of female ZNF638 FKO mice. Neutralizing circulating ANGPTL8 in female ZNF638 FKO mice abolished refeeding-induced TG elevation. Furthermore, we demonstrated that ZNF638 functions as a transcriptional repressor by recruiting HDAC1 for histone deacetylation and broad lipid metabolic gene suppression, including Angptl8 transcription inhibition. Moreover, we showed that the sexual dimorphism is possibly due to estrogen dependent regulation on ZNF638-ANGPTL8 axis. ConclusionWe revealed a role of ZNF638 in the regulation of triglyceride metabolism by affecting Angptl8 transcriptional level in adipose tissue with sexual dimorphism.

Lipolysis products from triglyceride-rich lipoproteins induce stress protein ATF3 in osteoblasts.

High fat diets overwhelm the physiological mechanisms for absorption, storage, and utilization of triglycerides (TG); consequently TG, TG-rich lipoproteins (TGRL), and TGRL remnants accumulate, circulate systemically, producing dyslipidemia. This associates with, or is causative for increased atherosclerotic cardiovascular risk, ischemic stroke, fatty liver disease, and pancreatitis. TGRL hydrolysis by endothelial surface-bound lipoprotein lipase (LPL) generates metabolites like free fatty acids which have proinflammatory properties. While osteoblasts utilize fatty acids as an energy source, dyslipidemia is associated with negative effects on the skeleton. In this study we investigated the effects of TGRL lipolysis products (TGRL-LP) on expression of a stress responsive transcription factor, termed activating transcription factor 3 (ATF3), reactive oxygen species (ROS), ATF3 target genes, and angiopoietin-like 4 (Angptl4) in osteoblasts. As ATF3 negatively associates with osteoblast differentiation, we also investigated the skeletal effects of global ATF3 deletion in mice. TGRL-LPincreased expression of Atf3, proinflammatory proteins Ptgs2 and IL-6, and induced ROS in MC3T3-E1 osteoblastic cells. Angptl4 is an endogenous inhibitor of LPL which was transcriptionally induced by TGRL-LP, while recombinant Angptl4 prevented TG-driven Atf3 induction. Atf3 global knockout male mice demonstrated increased trabecular and cortical microarchitectural parameters. In summary, we find that TGRL-LP induce osteoblastic cell stress as evidenced by expression of ATF3, which may contribute to the negative impact of dyslipidemia in the skeleton. Further, concomitant induction of Angptl4 in osteoblasts might play a protective role by reducing local lipolysis.

Hydrolases &amp; Lipases in GtoPdb v.2023.3

Listed in this section are hydrolases not accumulated in other parts of the Concise Guide, such as monoacylglycerol lipase and acetylcholinesterase. Pancreatic lipase is the predominant mechanism of fat digestion in the alimentary system; its inhibition is associated with decreased fat absorption. CES1 is present at lower levels in the gut than CES2 (P23141), but predominates in the liver, where it is responsible for the hydrolysis of many aliphatic, aromatic and steroid esters. Hormone-sensitive lipase is also a relatively non-selective esterase associated with steroid ester hydrolysis and triglyceride metabolism, particularly in adipose tissue. Endothelial lipase is secreted from endothelial cells and regulates circulating cholesterol in high density lipoproteins.