Effect of Shuangyu Tiaozhi Decoction on NPC1L1 and ABCG8 in Intestine of Hyperlipemic Model Rats / 中国实验方剂学杂志

Objective:To observe the expression levels of niemann-pick C1-like 1 (NPC1L1) and adenosine triphosphate-binding cassette transporters G8 (ABCG8) in intestine of hyperlipidemic model rats, in order to investigate the therapeutic mechanism of Shuangyu Tiaozhi decoction on hyperlipidemia. Method:A total of 40 SD rats were selected, including 8 for normal control group. The remaining 32 rats were used to establish hyperlipemic model. After modeling, the rats were randomly divided into the model group (equivalent normal saline), the high and low-dose Shuangyu Tiaozhi groups (15.6, 7.8 g·kg-1), and the Simvastatin group (4 mg·kg-1), with 8 in each group. They were given drugs by gavage for 8 weeks. The levels of total cholesterol (TC), triglyceride (TG) in serum and total cholesterol (TTC), free cholesterol (FTC) in liver of rats in each group were determined by biochemical and enzymatic methods. The morphological changes of liver were observed by hematoxylin-eosin (HE) staining, and the levels of expressions of NPC1L1, ABCG8 and liver X receptor-α (LXR-α) in intestine were detected by Real-time fluorescence quantitative polymerase chain reaction (Real-time PCR) and Western blot. The expression of ABCG8 protein was determined by immunohistochemistry. Result:After successful replication of the hyperlipidemia model, the blood lipid level was abnormally increased, and the liver steatosis became obvious in the model group compared with the normal control group. The expression levels of NPC1L1, LXR-α and ABCG8 increased significantly (PPα were significantly down-regulated, but ABCG8 was obviously up-regulated in a dose-dependent manner (PPPPPPConclusion:Shuangyu Tiaozhi decoction can reduce the blood lipid level of hyperlipemic rat model by reducing the absorption of cholesterol. Its mechanism may be correlated with the down-regulation of NPC1L1 expression and the up-regulation of ABCG8 expression.

Several proteins involved in absorption of cholesterol in small intestine / 军事医学

Several proteins are involved in the absorption of cholesterol in small intestine.Niemann-Pick C1 like 1 (NPC1L1) mainly mediates the absorption of cholesterol, and acyl-coenzyme A ( CoA)∶cholesterol acyltransferase 2 (ACAT2) catalyzes the free cholesterol absorpted by intestine into cholesterol ester,while unesterified free cholesterol is secreted into intestinal lumen by ATP-binding cassette(ABC) transporters G5/G8(ABCG5/ABCG8).Transcription factor liver X receptor( LXR) plays an important role in the process of intestinal cholesterol absorption.The research progress in NPC1L1,ABCG5/ABCG8,ACAT2 and LXR is reviewed in this article.

Polymorphism of ABCG5/ABCG8 gene (rs4299376) and lipid levels in Han Chinese with coronary heart disease / 第二军医大学学报

Objective: To explore the association between variant rs4299376 of ABCG5/ABCG8 gene with the risk of coronary heart disease (CHD) in Han Chinese and the association of related lipid levels with CHD. Methods: We collected blood samples from 290 CHD cases, 198 non-CHD controls and 331 healthy controls. The genomic DNA was acquired by the nucleic acid extraction automatic analyzer and the rs4299376 genotypes were analyzed by the Mass-ARRAY İPLEXR platform. Results: There were no significant differences in distribution of variant rs4299376 of ABCG5/ABCG8 gene among Han Chinese with CHD, non-CHD controls and healthy controls. There was no association between lipid levels and CHD in either total or male groups. While in female group, the triglyceride (TG) and total cholesterol (TC) were higher in CHD patients than in non-CHD controls (TG: 2. 23 ± 1. 05vs 1. 84 ± 1. 03, P = 0. 01; TC: 4. 7 9 ± 1. 17 vs 4. 36 ±1. 03, P = 0. 01). It was also found that, for those 60 years old and above, the CHD cases had a significantly lower high density lipoprotein (HDL) levll compared with non-CHD group (1. 09±0. 23 vs 1. 16±0. 25, P = 0. 03). Conclusion: There is no noticeable association between ABCG5/ ABCG8 rs4299376 polymorphism and the risk of CHD in Han Chinese. Female CHD patients have higher levels of TG and TC and when over 60 year old, CHD patients have a lower HDL level than non-CHD controls.

Effect of garlic extract on some serum biochemical parameters and expression of npc1l1, abca1, abcg5 and abcg8 genes in the intestine of hypercholesterolemic mice.

Some compounds in the garlic inhibit cholesterol synthesis, resulting in lowering of serum cholesterol and triglycerides and increase in HDL level. However, the mechanism of this specific effect is not fully understood. In the small intestine, ATP-binding cassette transporters G5, G8 and A1 (ABCG5, ABCG8 and ABCA1), as well as Niemann-Pick C1 like 1 (NPC1L1) protein have important roles in cholesterol metabolism. In this study, we evaluated the beneficial effect of aqueous extract of garlic on lipid profile and also expression of npc1l1, abca1, abcg5 and abcg8 genes in the intestine of N-Marry mice fed a high cholesterol diet as a possible mechanism of garlic effect. Twenty-four mice were randomly divided into three groups: Group 1: hypercholesterolmic (received chow + 2% cholesterol + 0.5% cholic acid); Group 2: garlic (received chow + 4% (w/w) garlic extract + 2% cholesterol + 0.5% cholic acid); and Group 3: received chow only. After one month, mice were anesthetized and blood was collected from their heart. The jejunum was removed, washed with PBS and entrocytes were scraped and used for the experiments. Serum lipids were measured enzymatically and expression of mRNA levels for the above-mentioned proteins was determined by semi-quantitative RT-PCR. Garlic extract significantly reduced serum lipids (p<0.05), compared with the hypercholesterolemic group. Expression of the intestinal npc1l1 was significantly decreased (p<0.01) in the garlic group, compared with the chow group, while abcg5 (p<0.01), abcg8 (p<0.01) and abca1 (p<0.05) expressions were significantly increased. In conclusion, this study reveals a possible mechanism for the beneficial effects of the garlic in lowering serum lipids by decreasing the intestinal lipid absorption and increasing excretion of cholesterol back into the intestinal lumen.

Effect of Thyroid Hormone to the Expression of ATP-binding Cassette Transporter ABCG5 / 대한갑상선학회지

BACKGROUND AND OBJECTIVES: Excretion of bile acid and free cholesterol of bile was important to maintain cholesterol homeostasis. ATP-binding cassette transporter G5 (ABCG5) and G8 (ABCG8) promoted biliary cholesterol excretion. In previous study, hepatic secretion of cholesterol and ABCG5/G8 expression are strongly stimulated in hypophysectomized rats during treatment with thyroid hormone. In this study, we aimed to evaluate the effect of thyroid hormone to expression of ABCG5 and G8 in mouse liver. MATERIALS AND METHODS: We administered thyroid hormone (T3) to C57BL/6 mice and then RNA and protein was isolated from liver. We isolated primary hepatocyte and administered T3 to evaluate in vitro effect. HepG2 cells were cotransfected with either a control plasmid or expression plasmids for human thyroid hormone receptor (hTR)beta/human retinoid X receptor (hRXR)alpha or human liver X receptor (hLXR)alpha in combination with reporter plasmids TK-LXRE3-LUC with or without T3. RESULTS: Serum total cholesterol was decreased after 5 days of T3 treatment. Expression of ABCG5/8 mRNA and ABCG5 protein was increased after T3 treatment. In primary hepatocytes, T3 also increased ABCG5/8 mRNA expression. LXRalpha mRNA was not increased by T3. However, when we cotransfected liver X receptor response element (LXRE) construct and TRbeta/RXRalpha with T3, the activity of LXRE containing construct was markedly increased. CONCLUSION: We confirmed that thyroid hormone increased expression of ABCG5/8. This result suggested that thyroid hormone played an important role in decreasing serum cholesterol through bile excretion.