Effect of Curcumin on the Gene Expression of Low Density Lipoprotein Receptors

Objective： To investigate the molecular mechanisms and effective target ponits of lipid-lowering drug, Rhizoma Curcumae Longae, and study the effect of curcumin on the expression of low density lipoprotein （LDL） receptors in macrophages in mice. Methods. Macrophages in mice were treated with curcumin, which was purified from the ethanolly extraction of Rhizoma Curcumae Longae for 24 h. The LDL receptors expressed in the macrophages were determined by enzyme-linked immunosorbent assay （ELISA） and assay of Dil labeled LDL uptake by flow cytometer. Results： It was found for the first time that 10 μmol/L-50 μmol/L curcumin could obviously up-regulate the expression of LDL receptor in macrophages in mice, and a dose-effect relationship was demonstrated. Conclusion： One of the lipid-lowering mechanisms of traditional Chinese medicine, Rhizoma Curcumae Longae, was completed by the effect of curcumin through the up-regulation of the expression of LDL receptor.

Overexpression of low-density lipoprotein receptor prevents neurotoxic polarization of astrocytes via inhibiting NLRP3 inflammasome activation in experimental ischemic stroke

Neurotoxic astrocytes are a promising therapeutic target for the attenuation of cerebral ischemia/reperfusion injury.Low-density lipoprotein receptor,a classic cholesterol regulatory receptor,has been found to inhibit NLR family pyrin domain containing protein 3(NLRP3)inflammasome activation in neurons following ischemic stroke and to suppress the activation of microglia and astrocytes in individuals with Alzheimer’s disease.However,little is known about the effects of low-density lipoprotein receptor on astrocytic activation in ischemic stroke.To address this issue in the present study,we examined the mechanisms by which low-density lipoprotein receptor regulates astrocytic polarization in ischemic stroke models.First,we examined low-density lipoprotein receptor expression in astrocytes via immunofluorescence staining and western blotting analysis.We observed significant downregulation of low-density lipoprotein receptor following middle cerebral artery occlusion reperfusion and oxygen-glucose deprivation/reoxygenation.Second,we induced the astrocyte-specific overexpression of low-density lipoprotein receptor using astrocyte-specific adeno-associated virus.Low-density lipoprotein receptor overexpression in astrocytes improved neurological outcomes in middle cerebral artery occlusion mice and reversed neurotoxic astrocytes to create a neuroprotective phenotype.Finally,we found that the overexpression of low-density lipoprotein receptor inhibited NLRP3 inflammasome activation in oxygen-glucose deprivation/reoxygenation injured astrocytes and that the addition of nigericin,an NLRP3 agonist,restored the neurotoxic astrocyte phenotype.These findings suggest that low-density lipoprotein receptor could inhibit the NLRP3-meidiated neurotoxic polarization of astrocytes and that increasing low-density lipoprotein receptor in astrocytes might represent a novel strategy for treating cerebral ischemic stroke.

Hypercholesterolemia,low density lipoprotein receptor and proprotein convertase subtilisin/kexin-type 9

Atherosclerotic cardiovascular disease is the main cause of mortality and morbidity in the world. Plasma levels of low density lipoprotein cholesterol （LDL-C） are positively correlated with the risk of atherosclerosis. High plasma LDL concentrations in patients with hypercholesterolemia lead to build-up of LDL in the inner walls of the arteries, which becomes oxidized and promotes the formation of foam cells, consequently initiating atherosclerosis. Plasma LDL is mainly cleared through the LDL receptor （LDLR） pathway. Mutations in the LDLR cause familiar hyperch- olesterolemia and increase the risk of premature coronary heart disease. The expression of LDLR is regulated at the transcriptional level via the sterol regulatory element binding protein 2 （SREBP-2） and at the posttranslational levels mainly through proprotein convertase subtilisin/kexin-type 9 （PCSK9） and inducible degrader of the LDLR （IDOL）. In this review, we summarize the latest advances in the studies of PCSK9.

Oxidized low-density lipoprotein receptor 1:a novel potential therapeutic target for intracerebral hemorrhage

Oxidized low-density lipoprotein receptor 1(OLR1)is upregulated in neurons and participates in hypertension-induced neuronal apoptosis.OLR1 deletion exerts protective effects on cerebral damage induced by hypertensive-induced stroke.Therefore,OLR1 is likely involved in the progress of intracerebral hemorrhage.In this study,we examined the potential role of OLR1 in intracerebral hemorrhage using a rat model.OLR1 small interfering RNA(10μL;50 pmol/μL)was injected into the right basal ganglia to knock down OLR1.Twenty-four hours later,0.5 U collagenase type VII was injected to induce intracerebral hemorrhage.We found that knockdown of OLR1 attenuated neurological behavior impairment in rats with intracerebral hemorrhage and reduced hematoma,neuron loss,inflammatory reaction,and oxidative stress in rat brain tissue.We also found that silencing of OLR1 suppressed ferroptosis induced by intracerebral hemorrhage and the p38 signaling pathway.Therefore,silencing OLR1 exhibits protective effects against secondary injury of intracerebral hemorrhage.These findings suggest that OLR1 may be a novel potential therapeutic target for intracerebral hemorrhage.

Function and Significance of Very Low Density Lipoprotein Receptor Subtype Ⅱ

To explore the functions of very low density lipoprotein receptor (VLDL-R) subtype II in lipoprotein metabolism and foam cells formation, the recombinant plasmid with the two subtypes cDNA was constructed respectively, the ldl-A7 cell lines were transfected and two cell lines expressing VLDL-R were obtained: one stably expressing the VLDLR with the O-linked sugar region (type I VLDLR) and the other without the O-linked sugar region (type II VLDLR). In the study on binding of VLDLR to their nuclein labeled natural ligands (VLDL and β-VLDL), it was found that surface binding of 125I-VLDL or 125I-β-VLDL of ldl-A7 cells transfected with type I VLDLR recombinant (ldl-A7-VRI) was more higher than that of ldl-A7 cells transfected with type II VLDLR recombinant (ldl-A7-VRII). After being incubated with VLDL for different time, the contents of triglyceride and total cholesterol in cells were mensurated, and the formation of foam cells and accumulation of lipid in cells was observed by oil-red O staining. The results showed that the contents of triglyceride and total cholesterol in ldl-A7-VR I were much higher than those in ldl-A7-VR II, and ldl-A7-VR I could transform into foam cells notably. It was suggested that type I VLDLR binds with relative higher affinity to VLDL and β-VLDL, and internalizes much more lipoprotein into cells. As a result, we can conclude that type I VLDLR plays a more important role in lipoprotein metabolism and foam cells formation than type II VLDLR.

Relationship between the low density lipoprotein receptor gene polymorphism and serum lipid levels in the Guangxi Bai Ku Yao population

Objectives Bai Ku Yao(White-trousers Yaos)is a special branch of Yao minority in China.They are now living in both Lihu and Baxu villages,Nandan County, Guangxi,China.The population size is about 30,000.The special customs and culture of Bai Ku Yao,including their special clothing,intra-ethnic marriages and alcohol intake are still completely conserved to the present day.In previous epidemiologic studies,we found that the serum lipid levels and the prevalence of hyperlipidaemia were lower in Bai Ku Yao than in Han Chinese from the same region.This ethnic difference in serum lipid profiles is still not well known.We hypothesized that there may be significant differences in some genetic polymorphismsssociation of low density lipoprotein receptor (LDL-R) genepolymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.Methods A total of 1024 subjects of Bai Ku Yao and 792 participants of Han Chinese were stud- ied by a stratified randomized cluster sampling.Epidemiological survey was carried out using internationally standardized methods.Information on demographics,socioeconomic status, and lifestyle factors was collected with standardized questionnaires. The height,weight,waist circumference,blood pressure, and serum total cholesterol(TC),triglyceride(TG), high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C),apolipoprotein(Apo) A1, and ApoB were measured.Body massindex(BMI,kg/m2) was calculated.Genotyping of the LDL-RAvaⅡwas performed by polymerse chain reaction and restriction fragment length polymorphism combined with gel electrophoresis,and then confirmed by direct sequencing.Results(l)The height,weight,serum TC,HDL-C,LDL-C,ApoAl levels and the ratio of ApoAl to ApoB were lower in Bai Ku Yao than in Han Chinese(P【0.01 for all),whereas the percentage of subjects who consumed alcohol or smoked cigarettes was higher in Bai Ku Yao than in Han Chinese(P【0.01 for each).(2) The frequency of A+ allele in Bai Ku Yao was 34.5%,and the frequencies of A-A-,A-A+ and A+A + genotypes were 42.6%,45.9%and 11.5%;respectively. The frequency of A+ allele in Han Chinese was 19.3%(P【0.001),and the frequencies of A-A-,A-A + and A+A+ genotypes were 64.9%,31.6%and 3.5%(P【0.001);respectively. The frequencies of A-A-,A-A+ and A+A+ genotypes in Bai Ku Yao were significant difference between males and females,between normal TC and high TC subgroup, and between normal LDL-C and high LDL-C subgroup (P【0.05 for all),whereas the frequencies of A- and A+ ? alleles in Han Chinese were significant difference between males and females(P【0.05).(3) Serum LDL-C levels in Bai Ku Yao were significant difference among the A-A-, A-A+ and A+A+ genotypes(P【0.05),the A+ carriers had higher serum LDL-C levels.Serum HDL-C levels in Han Chiese were significant difference among the A-A-,A-A + and A+A+ genotypes(P【0.01),the A+ carriers had higher serum HDL-C levels.(4) After adjusting other factors,the prevalence of LDL-C abnormality was still higher in Han Chiese than in Bai Ku Yao.The prevalence of TC abnormality in Han Chinese was almost twice high as in Bai Ku Yao. The age and diet were common risk factor for TC abnormality. No effect of AvaⅡgenotype or alcohol consumption on the TC abnormality was found,but the combination of geno-type and alcohol consumption can increase the prevalence of TC abnormality[Exp(B) =(1.154)].Age was negatively cor- related with TG level.Conclusions Serum TC and LDL-C levels were lower in Bai Ku Yao than in Han Chinese.There were significant differences in the AvaⅡallele and genotype frequencies between the he A+ carriers in Bai Ku Yao had higher serum LDL-C levels,whereas the A+ carriers in Han had higher serum HDL-C levels.Interactions between alcohol consumption or cigarette smoking and the LDL-R AvaⅡgenotype were also observed.The differences in the serum lipid profiles between the two ethnic groups might partly result from different genotypic frequency of LDL-R AvaⅡpolymorphism or differentgene-enviromental interactions.Bai Ku Yao and Han population,the frequency of A + allele was higher in Bai Ku Yao than in Han.T between the two ethnic groups.Therefore,the aim of the present study was to detect the

Lipid transport to avian oocytes and to the developing embryo

Studies of receptor-mediated lipoprotein metabolic pathways in avian species have revealed that physiological intricacies of specific cell types are highly analogous to those in mammals. A prime example for the power of com- parative studies across different animal kingdoms, elucidated in the chicken, is that the expression of different lipo- protein receptors in somatic cells and oocytes are the key to oocyte growth. In avian species, yolk precursor transport from the hen＇s liver to rapidly growing oocytes and the subsequent transfer of yolk nutrients via the yolk sac to the developing embryo are highly efficient processes. Oocytes grow from a diameter of 5 mm to 2.5-3 cm in only 7 days, and the yolk sac transfers nutrients from the yolk stored in the mature oocyte to the embryo within just 2 weeks. The underlying key transport mechanism is receptor-mediated endocytosis of macromolecules, i.e., of hepatically synthesized yolk precursors for oocyte growth, and of mature yolk components for embryo nutrition, respectively. Recently, the receptors involved, as well as the role of lipoprotein synthesis in the yolk sac have been identified. As outlined here, lipoprotein degradation/resynthesis cycles and the expression of lipoprotein receptors are not only coordinated with the establishment of the tbllicular architecture embedding the oocyte, but also with the generation of the yolk sac vasculature essential for nutrient transfer to the embryo.

Role of VLDL Receptor in the Process of Foam Cell Formation

The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β VLDL or low density lipoprotein (LDL), respectively for 24 h and 48 h, foam cells formation was identified by oil red O staining and cellular contents of triglyceride (TG) and total cholesterol (TC) were determined. The mRNA levels of LDLR, LDLR related protein (LRP) and VLDLR were detected by semi quantitative RT PCR. The results demonstrated that VLDL, β VLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or β VLDL showed markedly increased expression of VLDLR and decreased expression of LDLR, whereas LRP was up regulated slightly. For identifying the effect of VLDL receptor on cellular lipid accumulation, ldl A7 VR cells, which expresses VLDLR and trace amount of LRP without functional LDLR, was used to incubate with lipoproteins for further examination. The results elucidated that the uptake of triglyceride rich lipoprotein mediated by VLDLR plays an important role in accumulation of lipid and the formation of foam cells.

Genetically confirmed familial hypercholesterolemia in outpatients with hypercholesterolemia

Background Familial hypercholesterolemia （FH） is an autosomal dominant disorder of lipoprotein metabolism which can lead to premature coronary heart disease （pCHD）. There are about 3.8 million potential FH patients in China, whereas the clinical and genetic data of FH are limited. Methods Dutch Lipid Clinic Network （DLCN） criteria was used to diagnose FH in outpatients with hypercholesterolemia. Resequencing chip analysis combined with Sanger sequencing validation were used to identify mutations in the definite FH patients according to DLCN criteria. In silico analysis was conducted in mutations with previously unknown pathogenicity. Then, the novel mutant receptors were transfected into human embryo kidney 293 （HEK-293） cells. The binding and the internalization activities of the mu- tant receptors were analyzed by flow cytometry. Results The prevalence of definite FH in outpatients with hypercholesterolemia in this study is 3.2%. Using genetic testing, one homozygous FH （HoFH）, one heterozygous FH （HeFH） and three compound heterozygous FH patients were confirmed. Eight mutations in low-density lipoprotein receptor （LDLR） gene were identified, in which c.357delG was a novel mutation and co-segregated with the FH phenotype. Bioinformatic analysis confirmed that c.357delG was a pathogenic mutation. Furthermore, when compared with the wild-type LDLRs by flow eytometry analysis, the binding and internalization activities of c.357delG mutant LDLRs were reduced by 35% and 49%, respectively. Conclusions This study identified eight LDLR gene mutations in five patients with definite FH, in which c.357delG is a novel pathogenic mutation. These findings increase our understanding of the genetic spectrum of FH in China.

Effect of Insulin on the Differential Expression of VLDL Receptor Isoforms of SGC7901 Cell and Its Biological Implication

This study examined the effect of insulin on the expression of very low density lipoprotein receptor (VLDLR) subtypes of SGC7901 cells and discussed its biological implication.In vitro, moderately or poorly-differentiated human gastric adenocarcinoma cell line SGC7901 was incubated with insulin for different lengths of time, and then the expression of protein and RNA level in VLDLR subtypes were detected by Western blotting and real-time PCR, respectively.The results showed that, at certain time interval, insulin could down-regulate expression of type Ⅰ VLDLR and up-regulate the expression of type Ⅱ VLDLR in SGC7901 cells, at both protein and RNA level.We are led to conclude that insulin serves as a regulator in maintaining the balance between glucose and lipid metabolism in vivo, possibly through its effect on the differential expression of VLDLR subtypes.

Cholesterol metabolism in cholestatic liver disease and liver transplantation:From molecular mechanisms to clinical implications

The aim of this review is to enlighten the critical roles that the liver plays in cholesterol metabolism. Liver transplantation can serve as gene therapy or a source of gene transmission in certain conditions that affect cholesterol metabolism, such as low-density-lipoprotein(LDL) receptor gene mutations that are associated with familial hypercholesterolemia. On the other hand, cholestatic liver disease often alters cholesterol metabolism. Cholestasis can lead to formation of lipoprotein X(Lp-X), which is frequently mistaken for LDL on routine clinical tests. In contrast to LDL, Lp-X is non-atherogenic, and failure to differentiate between the two can interfere with cardiovascular risk assessment, potentially leading to prescription of futile lipid-lowering therapy. Statins do not effectively lower Lp-X levels, and cholestasis may lead to accumulation of toxic levels of statins. Moreover, severe cholestasis results in poor micellar formation, which reduces cholesterol absorption, potentially impairing the cholesterol-lowering effect of ezetimibe. Apolipoprotein B-100 measurement can help distinguish between atherogenic and non-atherogenic hypercholesterolemia. Furthermore, routine serum cholesterol measurements alone cannot reflect cholesterol absorption and synthesis. Measurements of serum non-cholesterol sterol biomarkers- such as cholesterol precursor sterols, plant sterols, and cholestanol- may help with the comprehensive assessment of cholesterol metabolism. An adequate cholesterol supply is essential for liver-regenerative capacity. Low preoperative and perioperative serum cholesterol levels seem to predict mortality in liver cirrhosis and after liver transplantation. Thus, accurate lipid profile evaluation is highly important in liver disease and after liver transplantation.

Ecto-F_1-ATPase: A moonlighting protein complex and an unexpected apoA-I receptor

Mitochondrial ATP synthase has been recently detected at the surface of different cell types, where it is a high affinity receptor for apoA-I, the major protein component in high density lipoproteins (HDL). Cell surface ATP synthase (namely ecto-F1-ATPase) expression is related to different biological effects, such as regulation of HDL uptake by hepatocytes, endothelial cell proliferation or antitumor activity of Vγ9/Vδ2 T lymphocytes. This paper reviews the recently discovered functions and regulations of ecto-F1-ATPase. Particularly, the role of the F1-ATPase pathway(s) in HDL-cholesterol uptake and apoA-Imediated endothelial protection suggests its potential importance in reverse cholesterol transport and its regulation might represent a potential therapeutic target for HDL-related therapy for cardiovascular diseases. Therefore, it is timely for us to better understand how this ecto-enzyme and downstream pathways are regulated and to develop pharmacologic interventions.

Proprotein convertase subtilisin/kexin type 9 inhibitor non responses in an adult with a history of coronary revascularization:A case report

BACKGROUND Familial hypercholesterolemia(FH)is an autosomal dominant disorder that is characterized by severely increased low-density lipoprotein(LDL)cholesterol levels.At the same time,elevated LDL levels accelerated the development of coronary heart disease.Several classes of drugs are currently in use to treat FH.Proprotein convertase subtilisin/kexin type 9 inhibitor(PCSK9i)is novel one of these.CASE SUMMARY This manuscript reports a case of FH that responded modestly after treatment with PCSK9i and statin drugs.Of even more concern is that the patient frequently admitted to the hospital during a 12-year follow-up period.Subsequently,we identified a heterozygous mutation,1448G>A(W483X)of the LDL receptor(LDLR)in this patient.The serum levels of PCSK9(proprotein convertase subtilisin/kexin type 9)in the patient was 71.30±26.66 ng/mL,which is close the average level reported in the literature.This LDLR mutation affects LDLR metabolism or structure,which may make it unsuitable for use of PCSK9i.CONCLUSION Our outcome demonstrates that LDLR-W483X represents a partial loss-of-function LDLR and may contribute to PCSK9i ineffective. In the meanwhile, additional measures aretherefore required (particularly with gene sequencing or change the treatment plan) must beinitiated as early as possible. Genetic testing for clinically challenging cases who do not respond toPCSK9i therapy is very helpful.

Investigation of the Distribution and Changes of VLDLR Subtype in Fibrotic Cardiac Muscles

Very low-density lipoprotein receptor (VLDLR) is the major receptor with which cells can uptake the triacylglycerol from blood. It is divided into two subtypes according to presence of O- linked sugar domain located in the VLDLR receptor immediately outside of the membrane. Type Ⅰ VLDLR contains the O-link domain, while type Ⅱhas no such domain. The type ⅠVLDLR are mainly found on the surface of human myocardial cells. The result of our quantitative polymerase chain reaction on the normal and fibrotic cardiac muscles showed that both subtypes and expression level of VLDLR on the myocardial cell surface did not vary significantly between the normal and the fibrotic cardiac muscles despite the presence of malfunction due to fibrosis. This finding suggests that fibrosis doesn't exert significant influence on the subtype and the expression of VLDLR on the sur- face of myocardial cells. Such inconsistence with the changes found in other fibrotic tissues is awaiting further studies.

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.

EFFECTS OF RAPAMYCIN ON INTRACELLULAR CHOLESTEROL HOMEOSTASIS OF GLOMERULAR MESANGIAL CELL IN THE PRESENCE OF INTERLEUKIN-1β

Objective To investigate the effects of rapamycin on cholesterol homeostasis of glomerular mesangial cells and the underlying mechanisms. Methods Intracellular cholesterol accumulation was measured by Oil Red O staining and high performance liquid chromatography. The effects of rapamycin on interleukin-1β（1L-1β）-induced mRNA and protein changes of low-density lipoprotein receptor （LDLR） and ATP-binding cassette transporter Al （ABCAl） were assayed by quantitative real-time PCR and Western blot. Transient expressions of 3 types of mammalian target of rapamycin （mTOR）, including mTOR-WT （wild type）, mTOR-RR （rapamycin resistant, with kinase activity）, and mTOR-RR-KD （rapamycin resistant, without kinase activity）, were obtained by plasmid transfection. Results Rapamycin had no significant influence on intracellular cholesterol concentration trader normal condition, but it significantly decreased the intracellular cholesterol concentration in the presence of IL-1β. Rapamycin dose-dependently suppressed the increased expression of LDLR induced by IL-1β and up-regulated the suppressed expression of ABCAl caused by IL-1β Transient expression of 3 types of mTOR all reduced ABCAl mRNA expression significantly, which all could be overroded by rapamycin. Conclusions Rapamycin may contribute to the maintaining of glomerular mesangial cell intracellular cholesterol homeostasis under inflammatory state by both reducing cholesterol uptake and increasing cholesterol effiux. And the effect may be not completely mediiated by mTOR.

Relationship between Insuline-like Growth Factor-I and Progesterone Secretion of Cultured Human Trophoblast Cells in Vitro

Objective To investigate the effect of insuline-like growth factor-Ⅰ （IGF-Ⅰ） on progesterone genesis and regulation. Methods Cytotrophoblast cells were collected by trypsin-collagenase digestion and percoll gradient centrifugation for primary culture. After stimulated with different concentrations（100 μg/ml, 10 μg/ml, 1 μg/ml, 0.1 μg/ml） of IGF-Ⅰ at the same time and with different duration（12 h,24 h,48 h, 72 h） of IGF-Ⅰ with the same concentration, progesterone levels in the media were measured by radioimmunoassay. Simultaneously, semiquantitative reverse transcriptase polymerase chain reaction （RT-PCR） was applied to determine the expression of low density lipoprotein receptor （LDLR） mRNA. Results Progesterone levels correlated positively with IGF-Ⅰ along with the IGF-Ⅰ concentration increasing, progesterone level began to increase at 12 h, and reached the climax at 48 h when cultured with 100 μg/L IGF-Ⅰ. The expression of LDLR mRNA was detectable in every group and accordant with variation of progesterone level. Conclusion Progesterone secretion has time- and dose-dependent effect on IGF-Ⅰ, and IGF-1 can up-regulate the expression of LDLR mRNA. IGF-Ⅰ may play an important role in promoting secretion of progesterone in trophoblast cells.

Type Ⅱ VLDLR promotes cell migration by up-regulation of VEGF, MMP2 and MMP7 in breast cancer cells

Objective： Very low density lipoprotein receptor （VLDLR） has been considered as a multiple function receptor due to binding numerous ligands, causing endocytosis and regulating cellular signaling. Our group previously reported that type II VLDLR overexpression in breast cancer tissues. The purpose of this study is to characterize type II VLDLR activities during cell migration using breast cancer cell lines. Methods： Western blotting was used to test protein expression. Cell migration was analyzed by Scratch wound assay. The mRNA expression was tested by realtime-PCR. Reporter assay was to test the transcription activity. Results： Scratch wound and Report assay indicated up-regulated VLDLR II expression promotes cell migration via activating Wnt/β-catenin pathway. The target genes such as VEGF, MMP2 and MMP7 were upregulated in VLDLR II overexpressed cells. On the contrary, cells treated with TFPI had an inhibition effect of cell migration response to down-regulation of VLDLR Ⅱ. Conclusion： Type Ⅱ VLDLR conferred a migration and invasion advantage by activating Wnt/β- catenin pathway, then up-regulating VEGF, MMP2 and MMP7 in breast cancer cells.

Structural basis of Semliki Forest virus entry using the very-low-density lipoprotein receptor

Alphaviruses are a group of important viruses that cause significant diseases in humans.Among them,Semliki Forest vi-rus(SFV)not only causes symptoms such as joint pain but also infects neuron cells and induces encephalitis in rodents.Recently,the very-low-density lipoprotein receptor(VLDLR)was identified as the cellular receptor for SFV entry.In this study,we present the cryo-electron microscopy structure of SFV bound to human VLDLR.VLDLR targets E1-DIII region of SFV using its membrane-distal LDLR class A(LA)repeats.Structural and functional analyses emphasize the synergistic role of multiple VLDLR repeats in the SFV entry.Remarkably,VLDLR’s binding mode to SFV closely mirrors that of minor group human rhinoviruses but differs significantly from other alphaviruses’interactions with receptors in the canyon re-gion of the E protein.We also assessed SFV binding to VLDLR or apolipoprotein E receptor 2(ApoER2)proteins in horses and mosquitoes and revealed their use of multiple but different LA repeats for binding.Our findings illuminate SFV’s cross-species infectivity,offering insights into potential antiviral strategies against alphavirus infections.

Research on Hepatocyte Regulation of PCSK9-LDLR and Its Related Drug Targets

The prevalence of hyperlipidemia has increased significantly due to genetic, dietary, nutritional and pharmacological factors, and has become one of the most common pathological conditions in humans. Hyperlipidemia can lead to a range of diseases such as atherosclerosis, stroke, coronary heart disease, myocardial infarction, diabetes, and kidney failure, etc. High circulating low-density lipoprotein cholesterol (LDL-C) is one of the causes of hyperlipidemia. LDL-C in the blood binds to LDL receptor (LDLR) and regulates cholesterol homeostasis through endocytosis. In contrast, proprotein convertase subtilisin/kexin type 9 (PCSK9) mediates LDLR degradation via the intracellular and extracellular pathways, leading to hyperlipidemia. Targeting PCSK9-synthesizing transcription factors and downstream molecules are important for development of new lipid-lowering drugs. Clinical trials regarding PCSK9 inhibitors have demonstrated a reduction in atherosclerotic cardiovascular disease events. The purpose of this review was to explore the target and mechanism of intracellular and extracellular pathways in degradation of LDLR and related drugs by PCSK9 in order to open up a new pathway for the development of new lipid-lowering drugs.