Evaluation of the participation of ABCA1 transporter in epicardial and mediastinal adipose tissue from patients with coronary artery disease

ABSTRACT Objective: Recent studies have shown a relationship between adipose tissue and coronary artery disease (CAD). The ABCA1 transporter regulates cellular cholesterol content and reverses cholesterol transport. The aim of this study was to determine the relationship between single nucleotide polymorphisms (SNPs) R230C, C-17G, and C-69T and their expression in epicardial and mediastinal adipose tissue in Mexican patients with CAD. Subjects and methods: The study included 71 patients with CAD and a control group consisting of 64 patients who underwent heart valve replacement. SNPs were determined using TaqMan probes. mRNA was extracted using TriPure Isolation from epicardial and mediastinal adipose tissue. Quantification and expression analyses were done using RT-qPCR. Results: R230C showed a higher frequency of the GG genotype in the CAD group (70.4%) than the control group (57.8%) [OR 0.34, 95% CI (0.14-0.82) p = 0.014]. Similarly, C-17G (rs2740483) showed a statistically significant difference in the CC genotype in the CAD group (63.3%) in comparison to the controls (28.1%) [OR 4.42, 95% CI (2.13-9.16), p = 0.001]. mRNA expression in SNP R230C showed statistically significant overexpression in the AA genotype compared to the GG genotype in CAD patients [11.01 (4.31-15.24) vs. 3.86 (2.47-12.50), p = 0.015]. Conclusion: The results suggest that the GG genotype of R230C and CC genotype of C-17G are strongly associated with the development of CAD in Mexican patients. In addition, under-expression of mRNA in the GG genotype in R230C is associated with patients undergoing revascularization.

ABCA1 transporter promotes the motility of human melanoma cells by modulating their plasma membrane organization

BACKGROUND: Melanoma is one of the most aggressive and deadliest skin tumor. Cholesterol content in melanoma cells is elevated, and a portion of it accumulates into lipid rafts. Therefore, the plasma membrane cholesterol and its lateral organization might be directly linked with tumor development. ATP Binding Cassette A1 (ABCA1) transporter modulates physico-chemical properties of the plasma membrane by modifying cholesterol distribution. Several studies linked the activity of the transporter with a different outcome of tumor progression depending on which type. However, no direct link between human melanoma progression and ABCA1 activity has been reported yet. METHODS: An immunohistochemical study on the ABCA1 level in 110 patients-derived melanoma tumors was performed to investigate the potential association of the transporter with melanoma stage of progression and prognosis. Furthermore, proliferation, migration and invasion assays, extracellular-matrix degradation assay, immunochemistry on proteins involved in migration processes and a combination of biophysical microscopy analysis of the plasma membrane organization of Hs294T human melanoma wild type, control (scrambled), ABCA1 Knockout ( ABCA1 KO) and ABCA1 chemically inactivated cells were used to study the impact of ABCA1 activity on human melanoma metastasis processes. RESULTS: The immunohistochemical analysis of clinical samples showed that high level of ABCA1 transporter in human melanoma is associated with a poor prognosis. Depletion or inhibition ofABCA1 impacts invasion capacities of aggressive melanoma cells. Loss of ABCA1 activity partially prevented cellular motility by affecting active focal adhesions formation via blocking clustering of phosphorylated focal adhesion kinases and active integrin ß3. Moreover, ABCA1 activity regulated the lateral organization of the plasma membrane in melanoma cells. Disrupting this organization, by increasing the content of cholesterol, also blocked active focal adhesion formation. CONCLUSION: Human melanoma cells reorganize their plasma membrane cholesterol content and organization via ABCA1 activity to promote motility processes and aggressiveness potential. Therefore, ABCA1 may contribute to tumor progression and poor prognosis, suggesting ABCA1 to be a potential metastatic marker in melanoma.

THE ATP-BINDING CASSETTE TRANSPORTER A1 GENE POLYMORPHISMS AND TYPE 2 DIABETES MELLITUS.

Insulin resistance (IR), secretion of insulin, and abnormalities of lipid metabolism are all markers of type 2 diabetes (T2DM), which is a progressive and complex metabolic disorder. Major risk factors for the development of T2DM were identified as genetic, environmental, and lifestyle factors. Several studies found that many genes contribute to T2DM susceptibility after glucose tolerance. Adenosine Binding Cassette Transporter Proteins 1 is a member of the ABC gene superfamily that is involved in cholesterol transport and HDL cholesterol (HDL-C) biosynthesis. Abnormal cholesterol metabolism, particularly high-density lipoprotein, has been related to genetic variations in the ABCA1 gene (HDL-C). Previous research suggested that ABCA1 gene polymorphisms may a hereditary risk factor for type 2 diabetes, along with lower HDL levels in various populations.

Effect of Five Huoxue Huayu Prescriptions on Blood Lipid Metabolism， Liver Tissue and ABCA1 and PPARγ Expression in New Zealand Rabbits with Blood Stasis Syndrome / 中国实验方剂学杂志

ObjectiveTo observe the effects of five Huoxue Huayu prescriptions on blood lipid metabolism， liver tissue and adenosine triphosphate binding cassette transporter A1 （ABCA1） and peroxisome proliferator-activated receptor γ（PPARγ） expression in New Zealand rabbits with blood stasis syndrome， and to compare their differences in order to provide laboratory evidence for clinical selection of prescriptions and drugs. MethodSeventy New Zealand rabbits were randomly divided into normal group （n=10） and model group （n=60）. The blood stasis syndrome was modeled by the method of starvation+high-fat feed+adrenaline. After the models were successfully established， they were randomly divided into Xuefu Zhuyutang（3.55 g·kg-1·d-1） group， Danshenyin（1.962 g·kg-1·d-1） group， Shixiaosan（0.56 g·kg-1·d-1） group， Huoluo Xiaolingdan（2.80 g·kg-1·d-1） group， and Taohong Siwutang（2.66 g·kg-1·d-1） group， and were given corresponding compound prescriptions by gavage. The normal group and model group were given the same dose of distilled water. After the treatment of 30 consecutive days， blood was taken from the abdominal aorta to detect the content of total cholesterol （TC）， triglycerides （TG）， high-density lipoprotein cholesterol （HDL-C）， low-density lipoprotein cholesterol（LDL-C） and apolipoprotein A1 （ApoA1）. Hematoxylin-eosin（HE） staining was used to observe the changes in liver tissue. Real-time polymerase chain reaction （Real-time PCR） and Western blot were used to detect the mRNA and protein expression of ABCA1 and PPARγ in liver tissue， respectively. ResultCompared with the conditions in the normal group， increased mRNA and protein levels of HDL-C， LDL-C， TG， TC， and PPARγ （P<0.01）， decreased ApoA1 level （P<0.05） and decreased mRNA and protein levels of ABCA1 （P<0.01） were found in the model group. Compared with the conditions in the model group， the HDL-C level in the five Huoxue Huayu prescriptions was lowered （P<0.05）， and lowered TG level in Xuefu Zhuyutang group and Shixiaosan group （P<0.05）， decreased LDL-C and TC levels in Shixiaosan group （P<0.05）， and increased ApoA1 level in the Huoluo Xiaolingdan group （P<0.01） and Taohong Siwutang group （P<0.05） were observed. Furthermore， the mRNA and protein levels of ABCA1 in Xuefu Zhuyutang group， Shixiaosan group， Huoluo Xiaolingdan group and Taohong Siwutang group were elevated （P<0.05， P<0.01）， and the elevated levels were higher than that of Danshenyin group （P<0.05）. The mRNA level of PPARγ in the five Huoxue Huayu prescriptions was reduced （P<0.01）， and its protein level was also decreased in Xuefu Zhuyutang group， Shixiaosan group， Huoluo Xiaolingdan group and Taohong Siwutang group （P<0.01）. ConclusionThe five Huoxue Huayu prescriptions had a certain therapeutic effect on dyslipidemia，which might be achieved by up-regulating the expression of ApoA1 and ABCA1 to promote the production of HDL-C and strengthen the excretion of dysfunctional HDL-C. And Xuefu Zhuyutang had the optimal effect in lowering lipid.

Isoflavones from Sojae Semen Praeparatum Regulate Lipid Metabolism in Atherosclerotic Mice Through PPARγ/LXRα/ABCA1 Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo study the effect of isoflavones from Sojae Semen Praeparatum （ISSP） on lipid metabolism in atherosclerotic mice， and decipher the underlying mechanism via the peroxisome proliferator-activated receptor gamma/liver X receptor alpha/ATP-binding cassette transporter A1 （PPARγ/LXRα/ABCA1） signaling pathway. MethodFifty ApoE-/- mice were randomly assigned into the model group， western medicine （atorvastatin calcium， 3.03 mg·kg-1） group， and low-， medium-， and high-dose ISSP （2.5， 5， 10 mg·kg-1， respectively） groups， with 10 rats in each group. Atherosclerosis model mice were established by bilateral ovariectomy and feeding high-fat diet. Another 10 ApoE-/- mice receiving ovariectomy and high-fat diet were taken as the sham group. Some mice died of postoperative infection， and finally 6 mice were included in each group. One week after operation， each group was administrated with corresponding drugs or equivalent amount of normal saline. After 12 weeks， the levels of triglyceride （TG）， total cholesterol （TC）， high-density lipoprotein cholesterol （HDL-C）， low-density lipoprotein cholesterol （LDL-C）， and non-esterified fatty acids （NEFAs） in serum and liver tissue were measured. The levels of tumor necrosis factor-α （TNF-α） and interleukin-6 （IL-6） in serum were detected by enzyme-linked immunosorbent assay （ELISA）. Hematoxylin-eosin （HE） staining and oil red O staining were used for observation of aortic plaque formation and liver lipid deposition. The mRNA and protein levels of PPARγ， LXRα， ABCA1， and ATP-binding cassette transporter G1 （ABCG1） in liver were determined by real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot. ResultCompared with the sham group， the modeling of atherosclerosis increased the aortic plaque area （P<0.01）， elevated the serum TC， TG， LDL-C， TNF-α， and IL-6 levels （P<0.01）， decreased the level of HDL-C （P<0.01）， increased the liver index （P<0.05） and the levels of TC， TG， and NEFAs in liver （P<0.01）， and caused obvious hepatic fat vacuoles and lipid deposition. In addition， the modeling down-regulated the mRNA levels of PPARγ， LXRα， ABCA1 in liver （P<0.05， P<0.01），and regulated the mRNA and protein levels of ABCG1（P<0.05， P<0.01）. Compared with the model group， atorvastatin calcium and middle-， high-dose ISSP reduced the serum TC， TG， LDL-C， TNF-α， and IL-6 levels （P<0.01）， decreased the liver index （P<0.01）， alleviated the liver fat vacuoles and lipid deposition， and increased the levels of TC， TG， and NEFAs in the liver （P<0.05， P<0.01）. Furthermore， they up-regulated the mRNA and protein levels of PPARγ， LXRα， ABCA1， and ABCG1 in the liver （P<0.05， P<0.01）. ConclusionISSP may regulate lipid metabolism through PPARγ/LXRα/ABCA1 signaling pathway to down-regulate the expression of inflammatory cytokines in serum and alleviate liver lipid deposition， thereby suppressing the formation of atherosclerotic plaque.

Tangshen formula improves cholesterol uptake and efflux of macrophages induced by high lipid via activating PGC-1α/LXR/ABCA1 pathway / 中国临床药理学与治疗学

AIM: To observe the effects of Tangshen formula (TSF) treatment on lipid efflux and uptake in sodium palmitate (PA) induced RAW264.7 macrophages. METHODS: After 200 μmol/L PA induced RAW264.7 macrophages, TSF and PGC-1α-siRNA were given to intervene respectively. The lipid content in the cells was detected by ELISA kit; intracellular lipid droplet deposition was detected by BODIPY 493/503 and Filipin staining. Western blot and Real-time PCR were used to detect the expression of PGC-1α, LXR, ABCA1 and CD36. RESULTS: TSF diminished the levels of TC, TG and intracellular lipid droplet deposition in PA-induced RAW264.7 macrophages. Western blot and Real-time PCR analysis showed that TSF could up-regulate the expression of PGC-1α, LXR, ABCA1 and down-regulate the expression of CD36. Furthermore, silencing PCG-1α by SiRNA significantly suppressed the effects of upregulating the expression of PGC-1α, LXR and ABCA1, and downregulating the CD36 expression with TSF treatment. CONCLUSION: TSF may extenuate intracellular lipid droplet deposition in macrophages by upregulating cholesterol efflux through activating the PGC-1α/LXR/ABCA1 pathway and inhibiting lipid uptake through down-regulateing the expression of CD36.

Anti-atherosclerotic activity of n-Hexane extract of Eleutherine americana Merr. on human macrophage primary cell culture

Atherosclerosis, a chronic disorder and the main pathogenesis of various cardiovascular diseases, is initiated by theformation of the macrophage foam cell at the subendothelial layer of the blood vessel wall. This study aimed toinvestigate the anti-atherosclerosis activity of n-hexane extract of Eleutherine americana Merr. (E. americana) onhuman macrophage through in vitro induction with oxidized-Low Density Lipoprotein (ox-LDL). The macrophagewas obtained from peripheral blood mononuclear cells (PBMCs) that were isolated from the serum of a healthy male.After the monocytes were maturely differentiated, the n-hexane extract of E. americana with a dose of 0.25, 1, and2 mg/ml was added before stimulation with ox-LDL. The foam cell was determined through Oil Red O staining, theexpressions of Toll-Like Receptor 4 (TLR4) and Adenosine Triphosphate-binding cassette transporter A1/G1 (ABCA1/ABCG1) were measured by immunofluorescence, and the activity of peroxisome-proliferator-activator receptor γ(PPARγ) was measured through Enzyme-linked immunosorbent assay. The results demonstrated that the foam celland the expression of TLR4 on the group with E. americana extract treatment were lower than the ox-LDL group (p <0.05). The expression of ABCA1 and ABCG1 on the group that was given the extract was higher than ox-LDL group(p < 0.05). This study concluded that the n-hexane extract of E. americana demonstrated anti-atherosclerosis activityon human macrophage induced with ox-LDL.

Essential Oil from Alpinia zerumbet Rhizome Inhibits Macrophage-derived Foam Cell Formation Via Modulating Expression of CD36 and ABCA1 / 中国实验方剂学杂志

Objective::To clarify the inhibitory effect of essential oil from Alpinia zerumbet rhizome (EOFAZ) on oxidized low-density lipoprotein (ox-LDL)-induced transformation of macrophage into foam cell and explore its possible mechanism. Method::THP-1 monocyte was incubated with 100 μg·L-1 phorbol myristate acetate (PMA) to grow into macrophage, experiment was divided into 4 groups as follows, control group, model group (80 mg·L-1 ox-LDL), EOFAZ at low dose (80 mg·L-1 ox-LDL+ 4 μg·L-1 EOFAZ)and EOFAZ at high dose (80 g·L-1 ox-LDL+ 20 μg·L-1 EOFAZ). Mathye thiazolye telrazliurn (MTT) method was employed to examine the influence of EOFAZ on macrophage viability. Western blot was used to analyze the expression level of cluster of differentiation 36(CD36) and ATP-binding cassette transporter A1(ABCA1) protein in macrophage. Enzyme-linked immunosorbent assay (ELISA) was used to detect cholesteryl ester contents in macrophage. Oil red O staining was applied to determine the accumulation of lipids in macrophage. Result::EOFAZ showed non-toxic effect on macrophage. Compared to control group, macrophage in model group displayed higher level of cholesteryl ester and lipid droplet(P<0.01), as well as significant increasing of CD36 expression (P<0.01), but no effect on ABCA1 expression. EOFAZ notably reduced the contents of lipids and cholesteryl ester(P<0.01), down-regulated expression of CD36 and up-regulated expression of ABCA1 in macrophage in comparison with the model group(P<0.01), indicating that EOFAZ inhibited transformation of macrophage into foam cell. Conclusion::EOFAZ could inhibit ox-LDL-induced transformation of macrophage into foam cell, the underlying mechanism may involves its ability to increase CD36 expression and decrease ABCA1 expression in macrophage.

Association of the ATP-binding Cassette Transporter A1 Gene Polymorphismo with Lipid Profile and Tye 2 Diabetes Mellitus

Diabetes remains unique among the main non-communicable ailments (NCDs) recognized by the World Health Organization (WHO), apart from the circulatory diseases, tumours, and long-lasting respiratory ailments. The current study aimed to determine the correlation between ABCA1 gene polymorphismo and lipid profile in type 2 diabetes mellitus patients. Serum samples from 100 type 2 diabetes mellitus patients (46 males and 54 females) and 50 standard subjects (26 males and 24 females) were colected from Najaf province/Irak. Fasting blood sugar (FBS), and lipid profiles (total cholesterol (TC), triglycerides (TH), HDL, LDL, and VLDL) were meassured. Plymerase chain reaction (PCR) with the Taq1 enzye was used for the amplification of the ABCA1 gene, which contains 525bp of the AABCA1 gene in the locus V825I. The present study revaled a positive corrrelation between FBS and body mass index (BMI) (r= 0.2390, p= 0.0463), TG (r = 0.1836, p= .01743), and VLDL (r = 0.1836, p = 0.1839). The frequencies of the GG genotype and the G allele were higher in the normal groups compared to the patientes (58% vs. 56% and 70% vs. 67%, respectively); conversely, the frequencies of the AA genotype (18% vs. 22%) and the A allele (30% vs. 33%) were higher in the patients compared to the normal groups. The data also showed a significant relationship between ABCA1 gene polymorphim and both TG and VLDL (P=0.007 for cach). There is relationship between the ABCA1 gene and HDL level. Additiionally, the G allele could be a defensive factor against diabetes mellitus in Iraqi peole (AU)

Catechins green tea upregulates the expression of ABCA1, ABCG1, and SRB1 in rats induced atherogenic diet

The efflux of cholesterol from macrophage to liver is known as reverse cholesterol transport (RCT). Impairedcholesterol efflux leads to cholesterol accumulation in macrophages. Therefore, how to increasing cholesterol effluxmay be an effective strategy for atherosclerosis prevention. Key molecules that play a vital role in the efflux ofcholesterol from macrophage are Adenosin Tri Phosphate (ATP)-binding casette transporters A1 and G. This study wasundertaken to clarify the effect of Catechins on the expression of specific transporters such as ATP-binding cassettesub-family A member 1 (ABCA1), ATP-binding cassette sub-family G member 1 (ABCG1) from macrophage to liver,and scavenger receptor class B type I (SRB1). This research was done on Wistar rats induced atherogenic diets. SRB1is one of the transporters to facilitate the delivery of cholesterol from the macrophage to the liver. The SRB1 pathwaymediated the selective uptake of cholesteryl ester. Catechins significantly increased the mRNA expression of ABCA1and ABCG1 in aorta as well as SRB1 of liver also increased. Thus, Catechins decreased the total cholesterol levels inaorta and serum. Catechins can be developed as a potential agent to increase ABCA1 to inhibit atherogenesis process.In conclusion, this study indicates that the potential anti-atherogenic properties of Catechins could be explained, atleast in part, as being due to upregulated expression of ABCA1, ABCG1, and SRB1 through activation liver X receptorsignaling pathway

Catechins green tea upregulates the expression of ABCA1, ABCG1, and SRB1 in rats induced atherogenic diet

The efflux of cholesterol from macrophage to liver is known as reverse cholesterol transport (RCT). Impairedcholesterol efflux leads to cholesterol accumulation in macrophages. Therefore, how to increasing cholesterol effluxmay be an effective strategy for atherosclerosis prevention. Key molecules that play a vital role in the efflux ofcholesterol from macrophage are Adenosin Tri Phosphate (ATP)-binding casette transporters A1 and G. This study wasundertaken to clarify the effect of Catechins on the expression of specific transporters such as ATP-binding cassettesub-family A member 1 (ABCA1), ATP-binding cassette sub-family G member 1 (ABCG1) from macrophage to liver,and scavenger receptor class B type I (SRB1). This research was done on Wistar rats induced atherogenic diets. SRB1is one of the transporters to facilitate the delivery of cholesterol from the macrophage to the liver. The SRB1 pathwaymediated the selective uptake of cholesteryl ester. Catechins significantly increased the mRNA expression of ABCA1and ABCG1 in aorta as well as SRB1 of liver also increased. Thus, Catechins decreased the total cholesterol levels inaorta and serum. Catechins can be developed as a potential agent to increase ABCA1 to inhibit atherogenesis process.In conclusion, this study indicates that the potential anti-atherogenic properties of Catechins could be explained, atleast in part, as being due to upregulated expression of ABCA1, ABCG1, and SRB1 through activation liver X receptorsignaling pathway.

Association of ABCA1 rare nonsynonymous variants with primary open angle glaucoma / 中华实验眼科杂志

Objective To explore the rare nonsynonymous variants of ABCA1 gene in primary open angle glaucoma (POAG).Methods A prospective cohort study was carried out.Three hundred and ninety-eight POAG patients and 198 healthy controls matched in age and gender were recruited from March 2017 to March 2018 in Eye and Ear Nose Throat (ENT) Hospital of Fudan University.The periphery blood of 2-5 ml from all the subjects was collected for extraction of DNA,and rare variant analysis of the ABCA1 gene was conducted by whole exome sequencing (WES) data of these subjects.The study protocol was approved by Ethic Committee of Eye and Ear Nose Throat Hospital of Fudan University and Sichuan Provincial People's Hospital (No.2016-32-1,and written informed consent was obtained from each subject prior to entering the study cohort.Results A total of 21 rare nonsynonymous variants (minor allele frequency MAF＜0.O1) were detected in the coding regions of ABCA1 gene in 27 subjects of the 398 POAG,with the detection rate of 6.8％.Among them,c.4310C＞A (p.Thr1437Asn),c.3772G＞T(p.Asp1258Tyr),c.775A＞G (p.Lys259Glu) and c.1507_1508insGAGGT (p.Glu503GlyfsX7) were four novel variants.In the 198 healthy controls,five rare nonsynonymous variants were detected in the ABCA1 gene from five subjects respectively,with the detection rate of 2.5％,the detection rate of nonsynonymous in POAG group was higher than that in healthy control group,showing a significant difference (x2=4.72,P =0.03,OR =2.81).Conclusions Rare nonsynonymous variants in ABCA1 is associated with the pathogenesis of POAG.These variants can enrich the variation spectrum of ABCA1.

Effect and mechanism of astragalus polysaccharide on lipid metabolism of macrophages / 西安交通大学学报(医学版)

Objective: To explore the effect of astragalus polysaccharide (APS) on oxidized low-density lipoprotein (ox-LDL)-induced lipid metabolism of macrophages and its underlying mechanism. Methods: The small interfering RNA (siRNA) targeting ATP binding cassette transporter A1 (ABCA1) was transfected into RAW 264.7 macrophages. Then the cells were stimulated with various concentrations of APS (20 mg/L, 60 mg/L and 150 mg/L), followed by the incubation with 50 mg/L ox-LDL for 24 h. qRT-PCR and Western blot were used to investigate the expression of ABCA1 mRNA and protein. Oil red O was used to analyze the level of foam cells. Lipid accumulation level was assessed by high performance liquid chromatography. [3H]-cholesterol was used to evaluate cholesterol efflux. Results: APS dose-dependently inhibited ox-LDL-induced formation of macrophage-derived foam cell compared with those in control group (P<0.05). HPLC analysis confirmed that APS attenuated lipid accumulation in a dose-dependent manner based on the decrease in ratio of cholesterol ester (CE)/total cholesterol (TC), concomitant with up-regulation of cholesterol efflux (P<0.05), indicating that APS might inhibit lipid deposition in macrophage by enhancing reverse cholesterol transport. Further more, APS dose-dependently increased ABCA1 mRNA and protein levels (P<0.05). When silencing ABCA1 expression with its specific siRNA, APS-inhibited lipid accumulation was significantly up-regulated, accompanied with the down-regulation of cholesterol efflux (P<0.05). Conclusion: APS may regulate lipid metabolism of macrophages by ABCA1-mediated progress of reverse cholesterol transport. Therefore, this study provides a potential target for the treatment of cardiovascular diseases triggered by vulnerable plaque.

Differences between the Molecular Mechanisms Underlying Ruptured and Non-Ruptured Carotid Plaques, and the Significance of ABCA1 / 대한뇌졸중학회지

BACKGROUND AND PURPOSE: Carotid plaques are a strong risk factor for ischemic stroke, and plaque rupture poses an even higher risk. Although many studies have investigated the pathogenic mechanisms of carotid plaque formation, few have studied the differences in molecular mechanisms underlying the rupture and non-rupture of carotid plaques. In addition, since early diagnosis and treatment of carotid plaque rupture are critical for the prevention of ischemic stroke, many studies have sought to identify the important target molecules involved in the rupture. However, a target molecule critical in symptomatic ruptured plaques is yet to be identified. METHODS: A total of 79 carotid plaques were consecutively collected, and microscopically divided into ruptured and non-ruptured groups. Quantitative polymerase chain reaction array, proteomics, and immunohistochemistry were performed to compare the differences in molecular mechanisms between ruptured and non-ruptured plaques. Enzyme-linked immunosorbent assay was used to measure the differences in ATP-binding cassette subfamily A member 1 (ABCA1) levels in the serum. RESULTS: The expression of several mRNAs and proteins, including ABCA1, was higher in ruptured plaques than non-ruptured plaques. In contrast, the expression of other proteins, including β-actin, was lower in ruptured plaques than non-ruptured plaques. The increased expression of ABCA1 was consistent across several experiments, ABCA1 was positive only in the serum of patients with symptomatic ruptured plaques. CONCLUSIONS: This study introduces a plausible molecular mechanism underlying carotid plaque rupture, suggesting that ABCA1 plays a role in symptomatic rupture. Further study of ABCA1 is needed to confirm this hypothesis.

Current understanding of ABCA1 in lipid accumulation / 基础医学与临床

ATP-binding cassette transporter A1 (ABCA1) is an membrane protein,using ATP for transferring substances,modulated by liver X receptors(LXRs), retinoic X receptors(RXRs), sterol regulatory element binding proteins(SREBPs), microRNAs and other upstream modulators.ABCA1 plays an important role in multiple pathways related to lipid accumulation.Upregulating ABCA1 expression may slow-down lipid accumulation, thus offers a promising strategy for metabolic diseases.

E17110 promotes reverse cholesterol transport with liver X receptor β agonist activity in vitro

Liver X receptor (LXR) plays an important role in reverse cholesterol transport (RCT), and activation of LXR could reduce atherosclerosis. In the present study we used a cell-based screening method to identify new potential LXRβ agonists. A novel benzofuran-2-carboxylate derivative was identified with LXRβ agonist activity: E17110 showed a significant activation effect on LXRβ with an EC50 value of 0.72 μmol/L. E17110 also increased the expression of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1) in RAW264.7 macrophages. Moreover, E17110 significantly reduced cellular lipid accumulation and promoted cholesterol efflux in RAW264.7 macrophages. Interestingly, we found that the key amino acids in the LXRβ ligand-binding domain had distinct interactions with E17110 as compared to TO901317. These results suggest that E17110 was identified as a novel compound with LXRβ agonist activity in vitro via screening, and could be developed as a potential anti-atherosclerotic lead compound.

Effect of high glucose on cholesterol efflux in renal tubular cell and intervention of anthocyanins / 中国药理学通报

Aim To investigate the effects of high glu-cose on cholesterol metabolism in renal tubular cells and the intervention of the anthocyanins. Methods HK-2 cells were grown in the DMEM medium supple-mented with 10% FBS and were divided into 5 groups:normal glucose group, high glucose group, mannitol group, C3G group and Cy group. Effect of anthocya-nins on cell viability was detected with MTT, and cho-lesterol accumulation was detected with Amplex Red Cholesterol Assay kit and Filipin staining. Expression of ABCA1 was detected with RT-qPCR and Western Blot. Results In compared with control groups, HG significantly promoted cholesterol mass inside the cell and decreased the cholesterol concentration in the me-dium after treatment for 24 h or 48 h. The levels of mRNA and protein of ABCA1 were detected with RT-qPCR and Western blot, and both were decreased in the presence of HG. Whereas treatment with C3G and Cy markedly attenuated HG-induced cholesterol mass inside the cell by up-regulating the expression of AB-CA1. Conclusions High glucose can reduce the ex-pressions of the ABCA1, and then decrease cholesterol efflux and increase the cholesterol accumulation in HK-2 cells. Anthocyanins can decrease cholesterol accu-mulation by up-regulating the expression of ABCA1.

EGCG upregulated ABCA1 expression by decreasing miR-33 a generation to reduce lipid accumulation of macrophage-derived foam cells / 中国药理学通报

Aim To investigate whether EGCG regu-lates ABCA1 expression by influencing the expression of miR-33 a to promote cholesterol efflux from macro-phages. Methods THP-1 macrophage-derived foam cells were established by co-incubated with oxLDL, and then treated with EGCG, and miR-33a expression was detected with Real-time PCR. THP-1 macrophage-derived foam cells were randomly divided into the fol-lowing groups: control group, 50 μmol · L-1 EGCG treatment group, 50 μmol · L-1 EGCG +80 nmol · L-1 miR-33a mimic treated group. Real-time PCR and Werstern blot was used to detect ABCA1 mRNA and protein expression, Oil Red O staining and high per-formance liquid chromatography were used to detect in-tracellular lipid content, and [3H] assay was used to determine cellular cholesterol efflux. Results EGCG could downregulate miRNA33 a expression in a dose-and time-dependent fashion within safe doses. EGCG significantly upregulated ABCA1 mRNA and protein expression, which could be inhibited after miRNA33 mimic transfected into cells, however. EGCG may re-duce lipid accumulation in THP-1 macrophage-derived foam cells, and this effect could also be weakened after miRNA33 mimic transfected. EGCG could reduce the accumulation of intracellular cholesterol,which was re-lated with EGCG promoting intracellular cholesterol ef-flux , and excess miRNA33 a transfected into cells could inhibit intracellular cholesterol efflux. Conclusion EGCG may upregulate ABCA1 expression by reducing miRNA33a generation, resulting in the promotion of cholesterol efflux from macrophages, which may be one of the molecular mechanisms of EGCG anti-atheroscle-rotic effect.

Effects of dihydromyricetin on the cholesterol efflux in macrophage derived foam cells / 天津医药

Objective To explore the effect of dihydromyricetin (DMY) on the cholesterol efflux in macrophage derived foam cells and analyze the possible mechanisms. Methods RAW 264.7 macrophages were incubated by oxidized low densi?ty lipoprotein (ox-LDL, 50 mg/L) for 48 h to induce foam cells. Subsequently, the foam cells were subdivided into control group (RPMI1640 media) and DMY 1-4 groups (10, 20, 40 and 80μmol/L) and cultured for 24 h. Cholesterol efflux from foam cells was examined by [3H] labed cholesterol. The high performance liquid chromatography assay was used to test the cellular contents of free cholesterol (FC), cholesteryl ester (CE) and total cholesterol (TC). The expression of ATP-binding cassette transporter A1 (ABCA1) was measured by Western blot assay. Results Compared with control group, cholesterol efflux was significantly increased, the content of FC, TC CE and CE/TC ratio were significantly decreased and expression of ABCA1 was significantly up-regulated in dose dependent manner in DMY (20, 40 and 80μmol/L) groups (P0.05). Conclusion DMY promotes the cholesterol efflux in the macro?phage derived foam cells, which may be related with the increase of ABCA1 induced by DMY.

Phosphatidylcholine-Mediated Aqueous Diffusion of Cellular Cholesterol Down-Regulates the ABCA1 Transporter in Human Skin Fibroblasts.

ATP-binding cassette protein A1 (ABCA1) is a cholesterol transporter that contributes to the active transport/removal of excess cellular cholesterol. ABCA1 expression is up-regulated when cells accumulate cholesterol. Aims: The purpose of this study was to determine any correlation between extracellular phospholipid levels and ABCA1 expression and function. Methodology: Human foreskin fibroblasts were incubated with cholesterol alone or cholesterol and phosphatidylcholine. Total RNA was isolated and subjected to end-point RT-PCR to compare ABCA1 transcript levels. Cell lysates were subjected to Western blot analysis to compare ABCA1 protein levels. Cells were loaded with radiolabeled cholesterol and cellular cholesterol efflux was measured in the presence and absence of apoE, a cholesterol acceptor. ApoE-dependent efflux was calculated as a measure of ABCA1-mediated efflux. Results: Here we show that incubation of cholesterol-loaded human skin fibroblasts with L-- phosphatidylcholine (PC) decreases ABCA1 mRNA and protein levels by 93% and 57%, respectively, compared to cells loaded with cholesterol alone. Similarly, PC treatment results in a 25% reduction in ABCG1 mRNA levels compared to cells treated with cholesterol alone, but there is no change in SR-BI transcript levels. Subsequent incubation of phospholipid-treated cells with a cholesterol acceptor such as apoE for 24 hours shows a 65% reduction in ABCA1-mediated cholesterol efflux compared to efflux in cells not treated with PC. During the lipid treatment itself, there is a 2.7-fold greater loss of cholesterol from PC treated cells compared to cells treated with cholesterol alone. Measurement of cholesterol in cellular lipid extracts reveals that cells incubated in the presence of phosphatidylcholine are significantly depleted of cholesterol having only 20% of the cholesterol compared to cells loaded with cholesterol alone. Conclusion: Thus, phosphatidylcholine facilitates removal of cellular cholesterol, thereby negating the cholesterol-dependent induction of ABCA1 message, protein and function.