Berberine promotes the development of atherosclerosis and foam cell formation by inducing scavenger receptor A expression in macrophage

Berberine is identified to lower the serum cholesterol level in human and hamster through the induction of low density lipoproteins （LDL） receptor in hepatic cells. To evaluate its potential in preventing atherosclerosis, the effect of berberine on atherosclerosis development in apolipoprotcin E-deficient （apoE^-/-） mice was investigated. In apoE^-/- mice, berberine induced in rivo foam cell formation and promoted atheroselerosis development. The foam cell formation induced by berberinc was also observed in mouse RAW264.7 cells, as well as in mouse and human primary macrophages. By inducing scavenger receptor A （SR-A） expression in macrophages, berberine increased the uptake of modified LDL （DiO-Ac-LDL）. Bcrberine-induced SR-A expression was also observed in macrophage foam cells in vivo and in the cells at atherosclerotic lesion. Analysis in RAW264.7 cells indicated that berberine induced SR-A expression by suppressing PTEN expression, which led to sustained Akt activation. Our results suggest that to evaluate the potential of a cholesterol-reducing compound in alleviating atherosclerosis, its effect on the ceils involved in atherosclerosis development, such as macrophages, should also be considered. Promotion of foam cell formation could counter-balance the beneficial effect of lowering serum cholesterol.

On the Impairment of Stress-Induced Changes in Triglyceride Levels via a Sub-Toxic Dose of Unmethylated Cytidine Phosphate Guanosine Oligodinucleotide (a Toll-Like Receptor 9 Ligand)

Changes in lipid metabolism have been implicated in protection against infectious diseases. In the first experiment of this study, we measured clinical lipid parameters in a murine model where the unmethylated cytidine phosphate guanosine (CpG) oligodinucleotide (ODN1826), a Toll-like receptor 9 (TLR9) agonist was administered in combination with D-galactosamine (GalN) that caused relatively liver-specific inflammation and toxicity. In the control mice group injected with phosphate-buffered saline (PBS) (acute psychological stress model associated with blood sampling), the serum triglyceride (TG) levels showed a rapid decrease followed by a rebound at 24 h as we have recently reported. However, such a TG rebound was impaired in the CpG/GalN- and solely CpG-treated groups of mice despite an absence of liver injury based on serum alanine aminotransferase levels in the latter group. Thus, the stress-associated serum TG rebound was abrogated by the injection of a sub-hepatotoxic CpG dose. In the second experiment, we simply measured the hepatic CD36 and SACRB1 (the gene for scavenger receptor B1 (SR-B1)) transcripts after the i.p. administration of PBS, CpG or CpG/GalN. There was a remarkable elevation of hepatic CD36 transcript expression in both the CpG- and CpG/GalN-treated mice at 8 h post-CpG injection whereas the increase in the PBS-treated mice was slower than the former two groups, suggesting that hepatic CD36 transcript expression is more pronounced in the combined stress models than under psychological stress alone. The individual mice data showed that the increase in CD36 expression was accompanied by a reduction in SCARB1 mRNA, showing reciprocal regulation between these two genes. Together with our previously reported findings, these data suggest that, in a murine model combining psychological stress with TLR-triggered hepatic inflammation, the psychological stress facilitates liver uptake of plasma TG (and its components fatty acids), but the subsequent re-esterification and/or release of TG-rich lipoproteins from the liver is impaired due to the concomitant TLR-signaling. We hypothesize that lipid metabolism during acute stress shifts toward an elevated hepatic uptake of lipids due to concomitant TLR signaling, facilitating the clearance of bacterial lipids by the liver.

Transgenic mice with overexpression of human scavenger receptor A on endothelial cells

Objectives To establish a new transgenic mouse model for determining the function and role of human scavenger receptor A (SR-A) in atherosclerosis in vivo.Methods Human scavenger receptor minigene-driven mouse tie-1 promoter was constructed and confirmed by endonuclease digestion and sequence analysis. Transgenic mice were generated via the microinjection method. PCR and Southern blot were used to screen the positive transgenic mice. RT-PCR and immunohistochemical analysis were used to detect the level and location of human SR-A Ⅰ expression in transgenic mice. The activity of human SR-A Ⅰ was determined by morphologic observation of aortic endothelial cells of transgenic mice under transmission electron microscopy.Results The electrophoresis assay showed the expected 4 fragments of 0.9 kb, 1.1 kb, 1.2 kb and 4.2 kb in the Sma Ⅰ digest and 2 fragments of 0.8 kb and 6.7 kb in Bgl Ⅱ digest of plasmids pTie-1/hSR-A. The fragment sequence of tie-1 promoter and human SR-A cDNA in plasmids pTie-1/hSR-A was correct and no ATG before the translation initiation sites of human SR-A was found by sequence analysis. 561 injected and surviving embryos with the purified human SR-A minigene were implanted into the oviducts of 19 ICR pseudopregnant mice. Among the 54 surviving pups from 13 foster mothers, 7 were identified by PCR and Southern blot analysis. The results of RT-PCR and imrnunohistochemical analysis showed human SR-A was specifically expressed on vascular endothelial cells of the aorta and renal artery, as well as hepatic sinusoidal endothelial cells in transgenic mice. Transmmion electron microscope (TEM) of aorta of transgenic mice showed that a large number of vesicles, multivesicle bodies and swollen mitochondria filled the plasma of endothelial cells.Conclusions A transgenic mouse model with overexpression of human SR-A in endothelial cells was successfully established. The transgene was integrated and transmitted into the chromosome of transgenic mice. Tie-1 promoter controlled the transgene to express in endothelial cells in mice. Pinocytic activity of aortic endothelial cells in transgenic mice was higher than that of C57BL/6J mice. Our studies will provide a new transcgenic model for investigation of atherosclerosis and functions of human SR-A.

Scavenger receptor BI: A multi-purpose player in cholesterol and steroid metabolism

Scavenger receptor class B type Ⅰ (SR-BI) is an important member of the scavenger receptor family of integral membrane glycoproteins. This review highlights studies in SR-BI knockout mice, which concern the role of SR-BI in cholesterol and steroid metabolism. SR-BI in hepatocytes is the sole molecule involved in selective uptake of cholesteryl esters from high-density lipoprotein (HDL). SR-BI plays a physiological role in binding and uptake of native apolipoprotein B (apoB)-containing lipoproteins by hepatocytes, which identif ies SR-BI as a multipurpose player in lipid uptake from the blood circulation into hepatocytes in mice. In adrenocortical cells, SR-BI mediates the selective uptake of HDL-cholesteryl esters, which is eff iciently coupled to the synthesis of glucocorticoids (i.e. corticosterone). SR-BI knockout mice suffer from adrenal glucocorticoid insuff iciency, which suggests that functional SR-BI protein is necessary for optimal adrenal steroidogenesis in mice. SR-BI in macrophages plays a dual role in cholesterol metabolism as it is able to take up cholesterol associated with HDL and apoBcontaining lipoproteins and can possibly facilitate cholesterol efflux to HDL. Absence of SR-BI is associated with thrombocytopenia and altered thrombosis susceptibility, which suggests a novel role for SR-BI in regulating platelet number and function in mice. Transgenic expression of cholesteryl ester transfer protein in humanized SR-BI knockout mice normalizes hepatic delivery of HDL-cholesteryl esters. However, other pathologies associated with SR-BI def iciency, i.e. increased atherosclerosis susceptibility, adrenal glucocorticoid insuffi ciency, and impaired platelet function are not normalized, which suggests an important role for SR-BI in cholesterol and steroid metabolism in man. In conclusion, generation of SR-BI knockout mice has signif icantly contributed to our knowledge of the physiological role of SR-BI. Studies using these mice have identif ied SR-BI as a multi-purpose player in cholesterol and steroid metabolism because it has distinct roles in reverse cholesterol transport, adrenal steroidogenesis, and platelet function.

The effective transfection of a low dose of negatively charged drug-loaded DNA-nanocarriers into cancer cells via scavenger receptors

DNA-nanotechnology-based nano-architecture scaffolds based on circular strands were designed in the form of DNA-nanowires(DNA-NWs) as a polymer of DNA-triangles. Circularizing a scaffold strand(84-NT) was the critical step followed by annealing with various staple strands to make stiff DNAtriangles. Atomic force microcopy(AFM), native polyacrylamide gel electrophoresis(PAGE), UVanalysis, MTT-assay, flow cytometry, and confocal imaging were performed to assess the formulated DNA-NWs and cisplatin(CPT) loading. The AFM and confocal microscopy images revealed a uniform shape and size distribution of the DNA-NWs, with lengths ranging from 2 to 4 mm and diameters ranging from 150 to 300 nm. One sharp band at the top of the lane(500 bp level) with the loss of electrophoretic mobility during the PAGE(native) gel analysis revealed the successful fabrication of DNA-NWs. The loading efficiency of CPT ranged from 66.85% to 97.35%. MTT and flow cytometry results showed biocompatibility of the blank DNA-NWs even at 95% concentration compared with the CPT-loaded DNANWs. The CPT-loaded DNA-NWs exhibited enhanced apoptosis(22%) compared to the apoptosis(7%)induced by the blank DNA-NWs. The release of CPT from the DNA-NWs was sustained at < 75% for 6 h in the presence of serum, demonstrating suitability for systemic applications. The IC_(50) of CPT@DNA-NWs was reduced to 12.8 nM CPT, as compared with the free CPT solution exhibiting an IC_(50) of 51.2 n M.Confocal imaging revealed the targetability, surface binding, and slow internalization of the DNA-NWs in the scavenger-receptor-rich cancer cell line(HepG2) compared with the control cell line.

Genetic variants of the class A scavenger receptor gene are associated with coronary artery disease in Chinese

The class A scavenger receptor, encoded by the macrophage scavenger receptor 1 （MSR1） gene, is a pattern recognition receptor （PPR） primarily expressed in macrophages. It has been reported that genetic polymorphisms of MSR1 are significantly associated with the number of diseased vessels and coronary artery narrowing greater than 20% in Caucasians. However, whether it links genetically to coronary artery disease （CAD） in Chinese is not defined. Here, we performed an independent case-control study in a Chinese population consisting of 402 CAD cases and 400 controls by genotyping ten single nucleotide polymorphisms （SNPs） of MSR1. We found that rs416748 and rs13306541 were significantly associated with an increased risk of CAD with per allele odds ratio （OR） of 1.56 [95% confidence interval （CI） = 1.28-1.90; P 〈 0.001] and 1.70 （95% CI = 1.27-2.27; P 〈 0.001）, re- spectively. Our results indicate that genetic variants of MSR1 may serve as predictive markers for the risk of CAD / in combination with traditional risk factors of CAD in Chinese population.

Biliary cholesterol secretion: More than a simple ABC

Biliary cholesterol secretion is a process important for 2 major disease complexes, atherosclerotic cardiovascular disease and cholesterol gallstone disease. With respect to cardiovascular disease, biliary cholesterol secretion is regarded as the f inal step for the elimination of cholesterol originating from cholesterol-laden macrophage foam cells in the vessel wall in a pathway named reverse cholesterol transport. On the other hand, cholesterol hypersecretion into the bile is considered the main pathophysiological determinant of cholesterol gallstone formation. This review summarizes current knowledge on the origins of cholesterol secreted into the bile as well as the relevant processes and transporters involved. Next to the established ATP-binding cassette (ABC) transporters mediating the biliary secretion of bile acids (ABCB11), phospholipids (ABCB4) and cholesterol (ABCG5/G8), special attention is given to emerging proteins that modulate or mediate biliary cholesterol secretion. In this regard, the potential impact of the phosphatidylserine flippase ATPase class Ⅰ type 8B member 1, the Niemann Pick C1-like protein 1 that mediatescholesterol absorption and the high density lipoprotein cholesterol uptake receptor, scavenger receptor class B type Ⅰ, is discussed.

FUCOIDIN INHIBITS OXIDIZED LOW DENSITY LIPOPROTEIN FROM INDUCING HUMAN PERIPHERAL BLOOD MONOCYTE EXPRESSION OF PROINFLAMMATORY CYTOKINES mRNA

Objective To study the significance of scavenger receptor class A(SR A)in mediating human peripheral blood monocyte to uptake oxidized low density lipoprotein(OxLDL) and promoting the atherosclerotic immuno pathological lesion in the local blood vessel. Methods With the Digoxenin labeled Oligonucleotide probes In situ Hybridization, this research investigated the effects of OxLDL on the mRNA expression of proinflammatory cytokines including MCP 1, bFGF, PDGF and IL 10 in the human peripheral blood monocyte and whether fucoidin, a peculiarly inhibitory ligand for SR A, would influence this process. Results Monocyte was significantly increased the mRNA expression of MCP 1, bFGF, PDGF and IL 10 in a dose dependent manner after incubating with OxLDL (10,15,20,25,30?mg·L -1 , respectively)for 24 hours( P < 0.001 ). Fucoidin(50,100,150,200,250?mg·mL -1 , respectively)completely inhibited OxLDL(20?mg·L -1 )from inducing monocyte the mRNA expression of above proinflammatory cytokines( P < 0.001 ). Conclusion OxLDL can stimulate human peripheral blood monocyte to give expression to proinflammatory cytokines mRNA in a dose dependent manner, while a peculiarly inhibitory ligand for SR A fucoidin has an obviously opposed role.

Upregulation of caveolin-1 and SR-B1 in mice with non-alcoholic fatty liver disease

BACKGROUND:Non-alcoholic fatty liver disease(NAFLD)is one of the most frequent causes of liver diseases,with markedly increased prevalence.However,its mechanisms are not clear.The present study was undertaken to illustrate the role of caveolin-1(cav1)and the scavenger receptor class B type 1(SR-B1)in NAFLD.METHODS:Adult male C57BL/6 mice were fed with a normal diet or high fat and cholesterol(HFC)diet for 14 weeks.The mice were sacrificed to collect plasma and harvest the liver;their plasma lipid concentration was measured.Hepatic cav1and SR-B1 mRNA and protein expression were determined by real-time quantitative polymerase chain reaction(qPCR)and Western blotting,respectively.In order to study cav1 and SR-B1distribution and change in hepatocytes,immunohistochemical analysis was performed.RESULTS:HFC diet increased plasma lipids,induced NAFLD and increased the liver/body weight ratio.Compared to the control mice(n=6),the mRNA and protein levels of cav1 and SR-B1 in liver tissue of the NAFLD mice(n=12)increased significantly(cav1 mRNA:1.536±0.226 vs 0.980±0.272,P【0.05;protein:0.643±0.240 vs 0.100±0.130,P【0.01;SR-B1 mRNA:1.377±0.125 vs 0.956±0.151,P【0.01;protein:2.156±0.507vs 0.211±0.211,P【0.01).Furthermore,both cav1 and SR-B1immunoreactivity increased and their distribution was also changed,mainly in the plasma membrane of hepatocytes,cytoplasm and membrane of lipid droplets and around.CONCLUSION:NAFLD is associated with increased concentration of plasma lipids and upregulation of hepatic cav1 and SR-B1 gene and protein expressions,which indicate that cav1 and SR-B1 might play crucial roles in the pathogenesis of NAFLD.

Role of sphingosine 1-phosphate in anti-atherogenic actions of high-density lipoprotein

The reverse cholesterol transport mediated by high-density lipoprotein (HDL) is an important mechanism for maintaining body cholesterol, and hence, the crucial anti-atherogenic action of the lipoprotein. Recent studies, however, have shown that HDL exerts a variety of anti-inflammatory and anti-atherogenic actions independently of cholesterol metabolism. The present review provides an overview of the roles of sphingosine 1-phosphate (S1P)/S1P receptor and apolipoprotein A-I/scavenger receptor class B type I systems in the anti-atherogenic HDL actions. In addition, the physiological significance of the existence of S1P in the HDL particles is discussed.

GRP78 inhibits macrophage adhesion via SR-A

Class A scavenger receptor （SR-A） plays an important role in macrophage adhesion. However, the underlying mechanism remains unclear. We previously found that 78 kDa glucose-regulated protein （GRP78） inhibited SR- A-mediated ligand internalization into macrophage by binding to SR-A. The aim of the study was to investigate whether GRP78 could regulate SR-A-mediated cell adhesion. We demonstrated that GRP78 bound directly to SR-A by fluorescence resonance energy transfer （FRET） assay. Overexpression of GRP78 inhibited macrophage adhesion via SR-A. These results suggest that GRP78 may act as an inhibitor of macrophage adhesion via SR-A.

HDL signaling and protection against coronary artery atherosclerosis in mice

Atherosclerosis is a leading underlying factor in cardiovascular disease and stroke,important causes of morbidity and mortality across the globe.Abundant epidemiological studies demonstrate that high levels of high density lipoprotein（HDL） are associated with reduced risk of atherosclerosis and preclinical,animal model studies demonstrate that this association is causative.Understanding the molecular mechanisms underlying the protective effects of HDL will allow more strategic approaches to development of HDL based therapeutics.Recent evidence suggests that an important aspect of the ability of HDL to protect against atherosclerosis is its ability to trigger signaling responses in a variety of target cells including endothelial cells and macrophages in the vessel wall.These signaling responses require the HDL receptor,scavenger receptor class B type 1（SR-B1）,an adaptor protein（PDZK1） that binds to the cytosolic C terminus of SR-B1,Akt1 activation and（at least in endothelial cells） activation of endothelial NO synthase（eNOS）.Mouse models of atherosclerosis,exemplified by apolipoprotein E or low density lipoprotein receptor gene inactivated mice（apoE or LDLR KO） develop atherosclerosis in their aortas but appear generally resistant to coronary artery atherosclerosis.On the other hand,inactivation of each of the components of HDL signaling（above）in either apoE or LDLR KO mice renders them susceptible to extensive coronary artery atherosclerosis suggesting that HDL signaling may play an important role in protection against coronary artery disease.

Susceptibility gene for stroke or cerebral infarction in the Han population in Hunan Province of China

The scavenger receptor class B type I gene can protect against atherosclerosis; a mononucleotide polymorphism is associated with differences in blood lipid metabolism, postprandial serum lipid levels, insulin resistance, coronary artery disease and familial hyperlipidemia. In this study, the scavenger receptor class B type I gene exon 1 G4A gene polymorphism in atherosclerotic cerebral infarction patients, cerebral hemorrhage patients and normal controls was detected using the polymerase chain reaction-restriction fragment length polymorphism method. The results showed that the GA ＋ AA genotype frequency of scavenger receptor class B type I gene G4A in atherosclerotic cerebral infarction patients was similar to that in cerebral hemorrhage patients and normal controls; however, the A allele frequency was significantly lower than that in normal controls. The serum level of high-density lipoprotein cholesterol in patients with the scavenger receptor class B type I gene G4A GA ＋ AA genotype was significantly higher, while the serum level of low-density lipoprotein cholesterol was significantly lower than that in patients with the GG genotype, in both the atherosclerotic cerebral infarction and cerebral hemorrhage groups. The serum level of high-density lipoprotein cholesterol in patients with the scavenger receptor class B type I gene G4A GA ＋ AA genotype was significantly higher, while the serum levels of low-density lipoprotein cholesterol and total cholesterol were significantly lower than those in normal controls with the GG genotype. Our experimental results suggest that the G4A polymorphism of the scavenger receptor class B type I gene is a possible predisposing risk factor for atherosclerotic cerebral infarction, and that it has no association with cerebral hemorrhage in the Hart population in Hunan province of China. The A allele is possibly associated with the metabolism of high-density and low-density lipoprotein cholesterol.

Overflow phenomenon in serum lutein after supplementation:a systematic review supported with SNPs analyses

Lutein,a type of carotenoids,is found to delay the onset and progression of age-related macular degeneration(AMD).Several lutein supplementation studies showed that after an initial increase,lutein serum levels demonstrated a subsequent decrease despite continuous supplementation.In this systematic literature review,this obscure phenomenon was tried to be explained.The subsequent drop in lutein levels was postulated due to down-regulation of lutein receptors scavenger receptor class B typeⅠ(SR-BI)in the gastrointestinal tract,upregulation of lutein degrading enzymeβ-carotene dioxygenase(BCDO2),or perhaps a combination of both.Some single nucleotides polymorphisms(SNPs)that could have influence on the occurrence of this phenomenon.To date,an exact scientific explanation for this phenomenon has not been established.Further research is needed to investigate this phenomenon in depth to reach an irrefutable explanation,giving that lutein is proven to be effective in delaying the onset and progression of AMD and its metabolism in the human body becomes of equal importance.

Anti-CD163-dexamethasone conjugate inhibits the acute phase response to lipopolysaccharide in rats

AIM: To study the effect of a new anti-CD163-dexamethasone conjugate targeting activated macrophages on the hepatic acute phase response in rats. METHODS: Wistar rats were injected intravenous with either the CD163 targeted dexamethasone-conjugate(0.02 mg/kg) or free dexamethasone(0.02 or 1 mg/kg) 24 h prior to lipopolysaccharide(LPS)(2.5 mg/kg intraperitoneal). We measured plasma concentrations of tumour necrosis factor-a(TNF-a) and interleukin 6(IL-6) 2 h post-LPS and liver m RNAs and serum concentrations of the rat acute phase protein a-2-macroglobulin(a-2-M) 24 h after LPS. Also, plasma concentrations of alanine aminotransferase and bilirubin were measured at termination of the study. Spleen weight served as an indicator of systemic steroid effects.RESULTS: The conjugate halved the a-2-M liver m RNA(3.3 ± 0.6 vs 6.8 ± 1.1, P < 0.01) and serum protein(201 ± 48 μg/mL vs 389 ± 67 μg/mL, P = 0.04) after LPS compared to low dose dexamethasone treated animals, while none of the free dexamethasone doses had an effect on liver m RNA or serum levels of a-2-M. Also, the conjugate reduced TNF-a(7208 ± 1977 pg/mL vs 21583 ± 7117 pg/mL, P = 0.03) and IL-6(15685 ± 3779 pg/mL vs 25715 ± 4036 pg/mL, P = 0.03) compared to the low dose dexamethasone. The high dose dexamethasone dose decreased the spleen weight(421 ± 11 mg vs 465 ± 12 mg, P < 0.05) compared to controls, an effect not seen in any other group.CONCLUSION: Low-dose anti-CD163-dexamethasone conjugate effectively decreased the hepatic acute phase response to LPS. This indicates an anti-inflammatory potential of the conjugate in vivo.

A DNA-based nanocarrier for efficient cancer therapy

The study aimed to achieve enhanced targeted cytotoxicity and cell-internalization of cisplatin-loaded deoxyribonucleic acid-nanothread(CPT-DNA-NT),mediated by scavenger receptors into HeLa cells.DNA-NT was developed with stiff-topology utilizing circular-scaffold to encapsulate CPT.Atomic force microscopy(AFM)characterization of the DNA-NT showed uniformity in the structure with a diameter of 50-150 nm and length of 300-600 nm.The successful fabrication of the DNA-NT was confirmed through native-polyacrylamide gel electrophoresis analysis,as large the molecular-weight(polymeric)DNA-NT did not split into constituting strands under applied current and voltage.The results of cell viability confirmed that blank DNA-NT had the least cytotoxicity at the highest concentration(512 nM)with a viability of 92%as evidence of its biocompatibility for drug delivery.MTT assay showed superior cytotoxicity of CPT-DNA-NT than that of the free CPT due to the depot release of CPT after DNA-NT internalization.The DNA-NT exhibited targeted cell internalizations with the controlled intracellular release of CPT(from DNA-NT),as illustrated in confocal images.Therefore,in vitro cytotoxicity assessment through flow cytometry showed enhanced apoptosis(72.7%)with CPT-DNA-NT(compared to free CPT;64.4%).CPT-DNA-NT,being poly-anionic,showed enhanced endocytosis via scavenger receptors.

Single amino acid mutation of SR-BI decreases infectivity of hepatitis C virus derived from cell culture in a cell culture model

AIM To investigate the effect of a single amino acid mutation in human class B scavenger receptor I(SR-BI) on the infectivity of cell culture-derived hepatitis C virus(HCVcc) in SR-BI knock-down Huh7-si SR-BI cells.METHODS Site-directed mutagenesis was used to construct the SR-BI S112 F mutation,and the mutation was confirmed by nucleotide sequencing. SR-BI knock-down Huh7-si SR-BI cells were transfected with SR-BI S112 F,SR-BI wild type(WT) and control plasmids,and then infected with HCVpp(HCV pseudoparticles) and hepatitis C virus derived from cell culture(HCVcc). A fluorescence assay was performed to analyze the effect of the S112 F mutation on HCV entry; quantitative real-time PCR,immunofluorescence,and Western blot assays were used to analyze the effect of the S112 F mutation on HCV infectivity. CHO cells expressing WT and SRBI S112 F were incubated with the HCV E2 protein expressed in HEK 293 T cells,and flow cytometry was performed to examine the ability of SR-BI S112 F to bind to the HCV E2 protein. Huh7-si SR-BI cells were transfected with SR-BI WT and the S112 F mutant,andthen Di I-HDL was added and images captured under the microscope to assess the ability of SR-BI S112 F to take up HDL.RESULTS The SR-BI S112 F mutation was successfully constructed. The S112 F mutation decreased the expression of the SR-BI m RNA and protein. SR-BI S112 F decreased HCV entry and HCVcc infectivity in Huh7-si SR-BI cells. The S112 F mutation impaired the binding of SR-BI to HCV E2 protein and decreased the HDL uptake of SR-BI.CONCLUSION The S112 F single amino acid mutation in SR-BI decreased the levels of the SR-BI m RNA and protein,as well as the ability of SR-BI to bind to the HCV E2 protein. Amino acid 112 in SR-BI plays important roles in HCV entry and the infectivity of HCVcc in vitro.

Transcriptome analysis differentially expressed genes with total carotenoid contents in pearl oyster(Pinctada fucata martensii)

Differentially expressed genes(DEGs)between individuals with high(HC)and low(LC)total carotenoid content(TCC)were sampled from a selected line of Pinctada fucata martensii with black shell in the prismatic layer.The expression levels of candidate genes were verified by qRT-PCR.Targeted resequencing was used to detect SNPs in a candidate gene,PmSR-BI.The association of TCC with SNPs in PmSR-BI was determined.Results showed that a total of 1025 DEGs were identified between HC and LC.The expression levels of the candidate gene PmSR-BI in HC were higher than those in LC.Seven SNPs in the exon and eight SNPs in the 5′regulatory regions of PmSR-BI were found.Association analysis showed that one SNP in the exon and two SNPs in the 5′regulatory regions of PmSR-BI were significantly associated with the TCC(P<0.05).All SNPs of PmSR-BI were divided into four blocks.CC haplotype in Block 1 and AG haplotype in Block 3 were significantly higher than other haplotypes.These results help elucidate the mechanism underlying carotenoid metabolism and develop marker-assisted breeding design in the species.

Expression pattern and tissue localization of the class B scavenger receptor BmSCRBQ4 in Bombyx moil

Class B scavenger receptors （SR-Bs） are cell surface glycoproteins involved in various physiological processes in vivo, including the transport and metabolism of lipids, binding and phagoeytosis of xenobiotics, and signaling. But little information is available about silkworm SR-Bs; it is necessary to study these SR-Bs for revealing their function. In this study, we cloned the full-length coding sequence of BrnSCRBQ4, a SR-B gene from the silkworm Bombyx mori L. We found that the BmSCRBQ4 gene consists of nine exons and eight introns, with an open reading frame of 1371 bp encoding 456 amino acids. Gene expression studies determined that BmSCRBQ4 messenger RNA （mRNA） was expressed in unfertilized eggs, during embryonic development and throughout the majority of the larval period. Expression of mRNA was detected in the mid gut, middle silk gland, posterior silk gland, head, integumentum, fat body, testes and the ovaries of the larval B. mori Dazao strain, as well as in the silkworm cell lines BmN and BmE. Protein expression studies found BmSCRBQ4 protein was expressed only in the testes, fat body and middle silk gland of larvae, as well as in the silkworm cell lines BmN and BmE. The BmSCRBQ4 protein showed variability in banding patterns in different tissues and cells when analyzed by Western blotting. Immunohistochemical staining showed that the BmSCRBQ4 protein localizes to the constitutive membranes or cellular membranes of these tissues. These results indicated that BmSCRBQ4 gene may play some physiologically relevant roles at the cell surface in each tissue.

Effect of Danhong injection on expressions of macrophage scavenger receptor 1 and sub-family A member 1 in human U937 cells

OBJECTIVE： To study the effects of Danhong injec- tion （DHI） on expression of the macrophage scaven- ger receptor 1 （MSR1） and ATP-binding cassette, sub-family A member 1 （ABCA1） genes, which en- code scavenger receptor-A I （SR-AI） and ATP-bind- ing cassette transporter 1 （ABCA1）, respectively, as a potential anti-atherosclerotic mechanism. METHODS： Human U937 cells were stimulated by in- cubation with 100 nM phorbo112-myristate 13-ace- tate （PMA） for 48 h.These stimulated, monocyte-like cells were then incubated for 24 h with 50 mg/L oxi- dized low-density lipoprotein （ox-LDL, to induce foam cell formation）, together with a liver X recep- tor （LXR） agonist or with different DHI concentra- tions. MSR1 and ABCA1 mRNA levels were mea- sured by fluorescence-based quantitative PCR. RESULTS： Compared with control cells （which re- ceived only ox-LDL）, cells treated with both ox-LDL and 10 IJmol/L LXR agonist showed lower MSR1 ex-pression （but this effect was not statistically signifi- cant, P〉0.05） and higher ABCA1 expression （P〈 0.01）. Cells that received ox-LDL and 3 mL/L DHI possessed higher MSR1 mRNA levels than the con- trols, whereas cells treated with ox-LDL and higher DHI concentrations （10, 30 or 60 mL/L） showed low- er MSR1 expression levels （but the differences ob- served between DHI concentration groups were not statistically significant, P〉0.05）. ABCA1 expression in cells treated with ox-LDL and 3, 10 or 30 mL/L DHI was higher than in the control cells, and increased with increasing DHI concentration （P〈0.05）. ABCA1 expression in cells treated with ox-LDL and the highest DHI concentration tested （60 mL/L） was not significantly different from that in the controls. ABCA1 mRNA levels in cells treated with ox-LDL and DHI were similar to, or lower than, those in cells treated with ox-LDL and the LXR agonist. CONCLUSION： DHI does not affect MSR1 mRNA lev- els in ox-LDL-treated U937 cells. However, at certain concentrations （10 and 30 mL/L）, DHI significantly increases ABCA1 mRNA levels. Therefore, the an- ti-atherosclerotic action of DHI might be mediated by an increased expression of ABCA1.