scholarly journals Mechanisms of fructose-induced hypertriglyceridaemia in the rat. Activation of hepatic pyruvate dehydrogenase through inhibition of pyruvate dehydrogenase kinase

1992 ◽  
Vol 282 (3) ◽  
pp. 753-757 ◽  
Author(s):  
O J Park ◽  
D Cesar ◽  
D Faix ◽  
K Wu ◽  
C H L Shackleton ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
De Novo ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Pyruvate Dehydrogenase Kinase ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Hepatic Lipogenesis ◽  
Daily Food ◽  
Dietary Fructose

1. The effects of purified diets containing 70% glucose or 70% fructose on the activation state of hepatic pyruvate dehydrogenase (PDHa), activity of mitochondrial PDH kinase, plasma triacylglycerols (TG) and hepatic lipogenesis de novo in rats were measured. 2. Plasma TG were significantly increased in the fructose-fed compared with the glucose-fed group (125 +/- 45 mg/dl versus 57 +/- 19 mg/dl; P less than 0.002) after 3-5 weeks on the diet despite less daily food intake. 3. Hepatic PDHa in fructose-fed rats was 144% of the value in glucose-fed rats (15.4 +/- 1.2% versus 10.7 +/- 0.5%; P less than 0.002), whereas cardiac muscle PDHa was not different (45.5 +/- 6.6% versus 41.0 +/- 7.8%). 4. Intrinsic hepatic PDH kinase activity was decreased to 34% of glucose-fed values by fructose feeding (-k = 3.56 +/- 0.39 versus 10.41 +/- 1.85 min-1; P less than 0.005). 5. The fractional contribution to very-low-density-lipoprotein palmitate from hepatic lipogenesis de novo, measured by a stable-isotope mass-spectrometric method, was 10.49 +/- 2.42% (n = 8) in fructose-fed rats versus 5.55 +/- 1.38% (n = 9) in glucose-fed rats (P less than 0.05), and 2.66 +/- 2.39% (n = 3) in chow-fed rats (P less than 0.05 versus fructose-fed group). The absolute contribution to circulating TG from lipogenesis de novo was also significantly higher in the fructose-fed than in the glucose-fed group (14.9 +/- 5.1 mg/dl versus 2.9 +/- 0.6 mg/dl; P less than 0.05) 6. Portal insulin concentrations were significantly higher in the fructose-fed rats (206 +/- 49 mu-units/ml versus 81 +/- 15 mu-units/ml; P less than 0.05). 7. In conclusion, dietary fructose appears to have a specific activating effect on hepatic PDH, mediated at least in part by inhibition of PDH kinase. These results are consistent with increased flux through hepatic PDH and synthesis of new fat, not just increased re-esterification of non-esterified fatty acids.

scholarly journals Effects of recombinant monokines on hepatic pyruvate dehydrogenase, pyruvate dehydrogenase kinase, lipogenesis de novo and plasma triacylglycerols. Abolition by prior fasting

1992 ◽  
Vol 284 (1) ◽  
pp. 129-135 ◽  
Author(s):  
M Blackham ◽  
D Cesar ◽  
O J Park ◽  
T C Vary ◽  
K Wu ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
De Novo ◽  
Pyruvate Dehydrogenase Complex ◽  
Interleukin 1 ◽  
Covalent Modification ◽  
Pyruvate Dehydrogenase Kinase ◽  
Hepatic Lipogenesis ◽  
Necrosis Factor Alpha ◽  
Intravenous Glucose ◽  
Ad Libitum

1. The effects of recombinant human tumour necrosis factor alpha (TNF) and murine interleukin-1 alpha (IL-1) on the activation state of the hepatic pyruvate dehydrogenase complex (PDHa), the activity of mitochondrial PDH kinase, hepatic lipogenesis de novo and plasma triacylglycerol (TG) concentrations were studied. 2. Monokine effects depended upon prior nutritional state. In rats fasted for 20 h or 45 h before monokine administration and refeeding (orally or with intravenous glucose), PDHa, TG and hepatic lipogenesis were not increased. In rats fed ad libitum, treatment with TNF plus IL-1 increased the contribution of hepatic lipogenesis to circulating TG to 550% of control values (P = 0.03) and plasma TG concentrations to 159% (P = 0.02), whereas PDHa increased slightly to 120% (P = 0.02) and liver glycogen content fell to 45.8% (P = 0.05) of control values. 3. Intrinsic hepatic PDH kinase activity was not changed by monokine treatment in rats fed ad libitum. 4. The increased lipogenesis de novo showed no correlation (r2 = 0.05, not significant) with hepatic PDHa in individual animals fed ad libitum. 5. In conclusion, these results suggest that monokines increase pyruvate flux through hepatic PDH in vivo in rats fed ad libitum primarily by mechanisms other than covalent modification of PDH. Prior nutritional status exerts a permissive effect for monokine stimulation of PDHa and lipogenesis, consistent with a substrate-mediated action, but the mechanism of this permissive effect remains uncertain.

scholarly journals Deficiency of ASGR1 in pigs recapitulates reduced risk factor for cardiovascular disease in humans

PLoS Genetics ◽  
2021 ◽  
Vol 17 (11) ◽  
pp. e1009891
Author(s):  
Baocai Xie ◽  
Xiaochen Shi ◽  
Yan Li ◽  
Bo Xia ◽  
Jia Zhou ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
De Novo ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Atherogenic Diet ◽  
Standard Diet ◽  
Low Levels ◽  
Reduced Risk

Genetic variants in the asialoglycoprotein receptor 1 (ASGR1) are associated with a reduced risk of cardiovascular disease (CVD) in humans. However, the underlying molecular mechanism remains elusive. Given the cardiovascular similarities between pigs and humans, we generated ASGR1-deficient pigs using the CRISPR/Cas9 system. These pigs show age-dependent low levels of non-HDL-C under standard diet. When received an atherogenic diet for 6 months, ASGR1-deficient pigs show lower levels of non-HDL-C and less atherosclerotic lesions than that of controls. Furthermore, by analysis of hepatic transcriptome and in vivo cholesterol metabolism, we show that ASGR1 deficiency reduces hepatic de novo cholesterol synthesis by downregulating 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), and increases cholesterol clearance by upregulating the hepatic low-density lipoprotein receptor (LDLR), which together contribute to the low levels of non-HDL-C. Despite the cardioprotective effect, we unexpectedly observed mild to moderate hepatic injury in ASGR1-deficient pigs, which has not been documented in humans with ASGR1 variants. Thus, targeting ASGR1 might be an effective strategy to reduce hypercholesterolemia and atherosclerosis, whereas further clinical evidence is required to assess its hepatic impact.

scholarly journals The Implications of PDK1–4 on Tumor Energy Metabolism, Aggressiveness and Therapy Resistance

2020 ◽  
Vol 10 ◽  
Author(s):  
Emine Atas ◽  
Monika Oberhuber ◽  
Lukas Kenner
Keyword(s):  
Pyruvate Dehydrogenase ◽  
De Novo ◽  
Pyruvate Dehydrogenase Complex ◽  
Acid Synthesis ◽  
Therapy Resistance ◽  
Pyruvate Dehydrogenase Kinase ◽  
Metabolic Shift ◽  
Cytotoxic Effects ◽  
Glycolytic Activity ◽  
Energetic State

A metabolic shift from oxidative phosphorylation (OXPHOS) to glycolysis—known as the Warburg effect—is characteristic for many cancers. It gives the cancer cells a survival advantage in the hypoxic tumor microenvironment and protects them from cytotoxic effects of oxidative damage and apoptosis. The main regulators of this metabolic shift are the pyruvate dehydrogenase complex and pyruvate dehydrogenase kinase (PDK) isoforms 1–4. PDK is known to be overexpressed in several cancers and is associated with bad prognosis and therapy resistance. Whereas the expression of PDK1–3 is tissue specific, PDK4 expression is dependent on the energetic state of the whole organism. In contrast to other PDK isoforms, not only oncogenic, but also tumor suppressive functions of PDK4 have been reported. In tumors that profit from high OXPHOS and high de novo fatty acid synthesis, PDK4 can have a protective effect. This is the case for prostate cancer, the most common cancer in men, and makes PDK4 an interesting therapeutic target. While most work is focused on PDK in tumors characterized by high glycolytic activity, little research is devoted to those cases where PDK4 acts protective and is therefore highly needed.

scholarly journals Fasting hepatic de novo lipogenesis is not reliably assessed using circulating fatty acid markers

2019 ◽  
Vol 109 (2) ◽  
pp. 260-268 ◽  
Author(s):  
Fredrik Rosqvist ◽  
Catriona A McNeil ◽  
Camilla Pramfalk ◽  
Sion A Parry ◽  
Wee Suan Low ◽  
...  
Keyword(s):  
Fatty Acid ◽  
De Novo ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Blood Lipid ◽  
De Novo Lipogenesis ◽  
Deuterated Water ◽  
Lipid Fractions ◽  
Habitual Diet ◽  
Fa Markers

ABSTRACT Background Observational studies often infer hepatic de novo lipogenesis (DNL) by measuring circulating fatty acid (FA) markers; however, it remains to be elucidated whether these markers accurately reflect hepatic DNL. Objectives We investigated associations between fasting hepatic DNL and proposed FA markers of DNL in subjects consuming their habitual diet. Methods Fasting hepatic DNL was assessed using 2H2O (deuterated water) in 149 nondiabetic men and women and measuring the synthesis of very low-density lipoprotein triglyceride (VLDL-TG) palmitate. FA markers of blood lipid fractions were determined by gas chromatography. Results Neither the lipogenic index (16:0/18:2n–6) nor the SCD index (16:1n–7/16:0) in VLDL-TG was associated with isotopically assessed DNL (r = 0.13, P = 0.1 and r = −0.08, P = 0.35, respectively). The relative abundances (mol%) of 14:0, 16:0, and 18:0 in VLDL-TG were weakly (r ≤ 0.35) associated with DNL, whereas the abundances of 16:1n–7, 18:1n–7, and 18:1n–9 were not associated. When the cohort was split by median DNL, only the abundances of 14:0 and 18:0 in VLDL-TG could discriminate between subjects having high (11.5%) and low (3.8%) fasting hepatic DNL. Based on a subgroup, FA markers in total plasma TG, plasma cholesteryl esters, plasma phospholipids, and red blood cell phospholipids were generally not associated with DNL. Conclusions The usefulness of circulating FAs as markers of hepatic DNL in healthy individuals consuming their habitual diet is limited due to their inability to discriminate clearly between individuals with low and high fasting hepatic DNL.

scholarly journals Roles of Achieved Levels of Low-Density Lipoprotein Cholesterol and High-Sensitivity C-Reactive Protein on Cardiovascular Outcome in Statin Therapy

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Myung Han Hyun ◽  
Yuchang Lee ◽  
Byoung Geol Choi ◽  
Jin Oh Na ◽  
Cheol Ung Choi ◽  
...  
Keyword(s):  
Statin Therapy ◽  
De Novo ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
High Sensitivity ◽  
Cardiovascular Outcome ◽  
Low Density ◽  
C Reactive Protein ◽  
Low Density Lipoprotein Cholesterol ◽  
Reactive Protein

In statin therapy, the prognostic role of achieved low-density lipoprotein cholesterol (LDL-C) and high-sensitivity C-reactive protein (hsCRP) in cardiovascular outcomes has not been fully elucidated. A total of 4,803 percutaneous coronary intervention (PCI)-naïve patients who prescribed moderate intensity of statin therapy were followed up. Total and each component of major adverse cardiovascular events (MACE) according to LDL-C and hsCRP quartiles were compared. The incidence of 5-year total MACEs in the highest quartile group according to the followed-up hsCRP was higher than that in the lowest quartile (hazard ratio (HR) = 2.16, p<0.001). However, there was no difference between the highest and lowest quartiles of the achieved LDL-C (HR = 0.95, p=0.743). After adjustment of potential confounders, the incidence of total death, de novo PCI, atrial fibrillation, and heart failure in the highest quartile of followed-up hsCRP, was higher than that in the lowest quartile (all p<0.05). However, other components except for de novo PCI in the highest quartile by achieved LDL-C was not different to that in the lowest quartile. These results suggest that followed-up hsCRP can be more useful for predicting future cardiovascular outcome than achieved LDL-C in PCI-naïve patients with statin therapy.

scholarly journals Identification of miR-185 as a regulator of de novo cholesterol biosynthesis and low density lipoprotein uptake

2013 ◽  
Vol 55 (2) ◽  
pp. 226-238 ◽  
Author(s):  
Muhua Yang ◽  
Weidong Liu ◽  
Christina Pellicane ◽  
Christine Sahyoun ◽  
Biny K. Joseph ◽  
...  
Keyword(s):  
De Novo ◽  
Cholesterol Biosynthesis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Uptake

scholarly journals An Untargeted Lipidomic Analysis Reveals Depletion of Several Phospholipid Classes in Patients with Familial Hypercholesterolemia on Treatment with Evolocumab

Biomedicines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1941
Author(s):  
Andrea Anesi ◽  
Alessandro Di Di Minno ◽  
Ilenia Calcaterra ◽  
Viviana Cavalca ◽  
Maria Tripaldella ◽  
...  
Keyword(s):  
Familial Hypercholesterolemia ◽  
High Performance ◽  
De Novo ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Unsaturation Index ◽  
Fatty Acyl ◽  
Phospholipid Classes

Rationale: Familial hypercholesterolemia (FH) is caused by mutations in genes involved in low-density lipoprotein cholesterol (LDL-C) metabolism, including those for pro-protein convertase subtilisin/kexin type 9 (PCSK-9). The effect of PCSK-9 inhibition on the plasma lipidome has been poorly explored. Objective: Using an ultra-high-performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry method, the plasma lipidome of FH subjects before and at different time intervals during treatment with the PCSK-9 inhibitor Evolocumab was explored. Methods and Results: In 25 FH subjects, heterozygotes or compound heterozygotes for different LDL receptor mutations, untargeted lipidomic revealed significant reductions in 26 lipid classes belonging to phosphatidylcholine (PC), sphingomyelin (SM), ceramide (CER), cholesteryl ester (CE), triacylglycerol (TG) and phosphatidylinositol (PI). Lipid changes were graded between baseline and 4- and 12-week treatment. At 12-week treatment, five polyunsaturated diacyl PC, accounting for 38.6 to 49.2% of total PC at baseline; two ether/vinyl ether forms; seven SM; five CER and glucosyl/galactosyl-ceramide (HEX-CER) were reduced, as was the unsaturation index of HEX-CER and lactosyl—CER (LAC-CER). Although non quantitative modifications were observed in phosphatidylethanolamine (PE) during treatment with Evolocumab, shorter and more saturated fatty acyl chains were documented. Conclusions: Depletion of several phospholipid classes occurs in plasma of FH patients during treatment with the PCSK-9 inhibitor Evolocumab. The mechanism underlying these changes likely involves the de novo synthesis of SM and CER through the activation of the key enzyme sphingomyelin synthase by oxidized LDL and argues for a multifaceted system leading to vascular improvement in users of PCSK-9 inhibitors.

scholarly journals Loss of Hepatic Surf4 Depletes Lipid Droplets in the Adrenal Cortex but Does Not Impair Adrenal Hormone Production

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiaole Chang ◽  
Yongfang Zhao ◽  
Shucun Qin ◽  
Hao Wang ◽  
Bingxiang Wang ◽  
...  
Keyword(s):  
Adrenal Gland ◽  
De Novo ◽  
Cholesterol Biosynthesis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipoprotein Cholesterol ◽  
Hormone Production ◽  
Adrenal Steroid ◽  
Adult Mice ◽  
Cholesterol Levels

The adrenal gland produces steroid hormones to play essential roles in regulating various physiological processes. Our previous studies showed that knockout of hepatic Surf4 (Surf4LKO) markedly reduced fasting plasma total cholesterol levels in adult mice, including low-density lipoprotein and high-density lipoprotein cholesterol. Here, we found that plasma cholesterol levels were also dramatically reduced in 4-week-old young mice and non-fasted adult mice. Circulating lipoprotein cholesterol is an important source of the substrate for the production of adrenal steroid hormones. Therefore, we investigated whether adrenal steroid hormone production was affected in Surf4LKO mice. We observed that lacking hepatic Surf4 essentially eliminated lipid droplets and significantly reduced cholesterol levels in the adrenal gland; however, plasma levels of aldosterone and corticosterone were comparable in Surf4LKO and the control mice under basal and stress conditions. Further analysis revealed that mRNA levels of genes encoding enzymes important for hormone synthesis were not altered, whereas the expression of scavenger receptor class B type I (SR-BI), low-density lipoprotein receptor (LDLR) and 3-hydroxy-3-methyl-glutaryl-CoA reductase was significantly increased in the adrenal gland of Surf4LKO mice, indicating increased de novo cholesterol biosynthesis and enhanced LDLR and SR-BI-mediated lipoprotein cholesterol uptake. We also observed that the nuclear form of SREBP2 was increased in the adrenal gland of Surf4LKO mice. Taken together, these findings indicate that the very low levels of circulating lipoprotein cholesterol in Surf4LKO mice cause a significant reduction in adrenal cholesterol levels but do not significantly affect adrenal steroid hormone production. Reduced adrenal cholesterol levels activate SREBP2 and thus increase the expression of genes involved in cholesterol biosynthesis, which increases de novo cholesterol synthesis to compensate for the loss of circulating lipoprotein-derived cholesterol in the adrenal gland of Surf4LKO mice.

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