SCARB1 Research Articles

Effects of SNVs in ABCA1, ABCG1, ABCG5, ABCG8, and SCARB1 Genes on Plasma Lipids, Lipoproteins, and Adiposity Markers in a Brazilian Population.

Several proteins are involved in cholesterol homeostasis, as scavenger receptor class B type I and ATP-binding cassette (ABC) transporters including ABCA1, ABCG1, ABCG5, and ABCG8. This study aimed to determine the effects of single nucleotide variants (SNVs) rs2275543 (ABCA1), rs1893590 (ABCG1), rs6720173 (ABCG5), rs6544718 (ABCG8), and rs5888 (SCARB1) on plasma lipids, lipoproteins, and adiposity markers in an asymptomatic population and its sex-specific effects. Volunteers (n = 590) were selected and plasma lipids, lipoproteins, and adiposity markers (waist-to-hip and waist-to-height ratios, lipid accumulation product and body adiposity index) were measured. Genomic DNA was isolated from peripheral blood cells according to the method adapted from Gross-Bellard. SNVs were detected in the TaqMan® OpenArray® Real-Time polymerase chain reaction platform and data analyses were performed using the TaqMan® Genotyper Software. The rs2275543*C point to an increase of high-density lipoprotein size in females while in males very-low-density lipoprotein, cholesterol, and triglycerides were statistically lower (P value < 0.05). The rs1893590*C was statistically associated with lower apolipoprotein A-I levels and higher activities of paraoxonase-1 and cholesteryl ester transfer protein (P value < 0.05). The rs6720173 was statistically associated with an increase in cholesterol and low-density lipoprotein cholesterol in males; moreover, rs6544718*T reduced adiposity markers in females (P value < 0.05). Regarding the rs5888, a decreased adiposity marker in the total population and in females occurred (P value < 0.05). Multivariate analysis of variance showed that SNVs could influence components of high-density lipoprotein metabolism, mainly through ABCG1 (P value < 0.05). The ABCA1 and ABCG5 variants showed sex-specific effects on lipids and lipoproteins, while SCARB1 and ABCG8 variants might influence adiposity markers in females. Our data indicate a possible role of ABCG1 on HDL metabolism.

HDL receptor/Scavenger receptor B1-Scarb1 and Scarb1-like mediate the carotenoid-based red coloration in fish

Both carotenoids and pteridine pigments can produce colors ranging from red to yellow and participate in mate choice, antioxidant, and immunity processes in animals. Common carp (Cyprinus carpio) variants with red coloration have been selectively bred for more than a thousand years, yet the mechanism that regulates coloration remains poorly understood. Here we provided experimental evidence that the red coloration in common carp varieties was carotenoid-based and was regulated by the carotenoid transport genes Scarb1 and Scarb1-like (high density lipoprotein (HDL) receptor/ scavenger receptor B type 1, also known as SR-BI). We found that carotenoids rather than pteridine pigments were specific to whole red (WR) but absent in whole white (WW) Oujiang color common carp (Cyprinus carpio var. color). Scarb1 and its novel paralog gene Scarb1-like were the most significant carotenoid metabolism-related genes differentially expressed between WR and WW, whereas no difference was detected for the Gch1 (GTP cyclohydrolase 1) gene, which acted as a rate limiting enzyme in the pteridine pathway. Disruption of Scarb1, Scarb1-like, and Gch1 using CRISPR/Cas9 technology resulted in regional red skin fading into white color in Scarb1 and Scarb1-like mutated WR (S+/−), leading to a decrease and a complete loss of astaxanthin and lutein in the red and white areas, respectively. However, no skin color variations were observed in Gch1 mutated WR fishes. In addition, disruption of the two Scarb1 genes and Gch1 together in WR caused red color variations similar to those observed in S+/− WR. Finally, carotenoids supplementation recovered the red color but had poorly effects on the white color in S+/− WR. This study revealed a plausible molecular mechanism responsible for red and white body colors and may benefit selective breeding programs of ornamental and cultured fish.

ZBTB32 performs crosstalk with the glucocorticoid receptor and is crucial in glucocorticoid responses to starvation

SummaryThe hypothalamic-pituitary-adrenal (HPA) axis forms a complex neuroendocrine system that regulates the body’s response to stress such as starvation. In contrast with the glucocorticoid receptor (GR), Zinc finger and BTB domain containing 32 (ZBTB32) is a transcription factor with poorly described functional relevance in physiology. This study shows that ZBTB32 is essential for the production of glucocorticoids (GCs) in response to starvation, since ZBTB32−/− mice fail to increase their GC production in the absence of nutrients. In terms of mechanism, GR-mediated upregulation of adrenal Scarb1 gene expression was absent in ZBTB32−/− mice, implicating defective cholesterol import as the cause of the poor GC synthesis. These lower GC levels are further associated with aberrations in the metabolic adaptation to starvation, which could explain the progressive weight gain of ZBTB32−/− mice. In conclusion, ZBTB32 performs a crosstalk with the GR in the metabolic adaptation to starvation via regulation of adrenal GC production.

HDL biodistribution and brain receptors in zebrafish, using HDLs as vectors for targeting endothelial cells and neural progenitors

High density lipoproteins (HDLs) display pleiotropic functions such as anti-inflammatory, antioxidant, anti-protease, and anti-apoptotic properties. These effects are mediated by four main receptors: SCARB1 (SR-BI), ABCA1, ABCG1, and CD36. Recently, HDLs have emerged for their potential involvement in brain functions, considering their epidemiological links with cognition, depression, and brain plasticity. However, their role in the brain is not well understood. Given that the zebrafish is a well-recognized model for studying brain plasticity, metabolic disorders, and apolipoproteins, it could represent a good model for investigating the role of HDLs in brain homeostasis. By analyzing RNA sequencing data sets and performing in situ hybridization, we demonstrated the wide expression of scarb1, abca1a, abca1b, abcg1, and cd36 in the brain of adult zebrafish. Scarb1 gene expression was detected in neural stem cells (NSCs), suggesting a possible role of HDLs in NSC activity. Accordingly, intracerebroventricular injection of HDLs leads to their uptake by NSCs without modulating their proliferation. Next, we studied the biodistribution of HDLs in the zebrafish body. In homeostatic conditions, intraperitoneal injection of HDLs led to their accumulation in the liver, kidneys, and cerebral endothelial cells in zebrafish, similar to that observed in mice. After telencephalic injury, HDLs were diffused within the damaged parenchyma and were taken up by ventricular cells, including NSCs. However, they failed to modulate the recruitment of microglia cells at the injury site and the injury-induced proliferation of NSCs. In conclusion, our results clearly show a functional HDL uptake process involving several receptors that may impact brain homeostasis and suggest the use of HDLs as delivery vectors to target NSCs for drug delivery to boost their neurogenic activity.

Cell Signaling in Diabetic Dyslipidemia

Diabetes accompanies several metabolic complications and poor production and clearance of lipoprotein is one of them. Type 2 diabetes mellitus is linked with atherosclerosis, though exact mechanism is still unclear. There are different complications of type 2 diabetes mellitus. Dyslipidemia is one of them. It has been documented that deranged lipid profile is caused by insulin resistance. Dyslipidemia arises due to low level of high density lipoproteins and high level of triglycerides. Diabetic dyslipidimia occurs due to imbalance in reverse cholesterol transport mechanism which is a major risk for cardiovascular diseases. Reverse cholesterol transport is regulated by cell surface receptors scavenger receptor B1 and ATP binding cassette protein-1. These are HDL binding receptors and help to maintain balance of HDL. Genetic and epigenetic factors influence the regulation of cell surface receptors. It plays a significant role in lipid homeostasis. HDL receptors are encoded by SCARB1 and ABCA1 genes. Peroxisome proliferator activated receptor alpha (PPARα) is a down-stream transcriptional activator of SCARB1, ABCA1 and ApoA1 genes.

Role of the Mevalonate Pathway in Adrenocortical Tumorigenesis.

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is the rate-limiting enzyme of the mevalonate pathway, which generates cholesterol and non-sterol compounds such as isoprenoid, which are involved in key steps of tumorigenesis such as cell growth and proliferation. Our aim was to evaluate the role of the mevalonate pathway in adrenocortical tumors (ACTs). Expression pattern of HMGCR, FDFT1, LDLR, SCARB1, StAR, TSPO, CYP11A1, CYP11B1, CYP17A1, CYP21A1, and HSD3B1 genes, involved in the mevalonate pathway and steroidogenesis, was quantified by real-time RT-PCR in 46 ACT [14 adenomas (ACA) and 11 carcinomas (ACC) from adults and 13 ACA and 8 ACC from pediatric patients]. Effects of the mevalonate pathway inhibition on NCI-H295A cell viability was assessed by colorimetric assay. HMGCR was overexpressed in most adult ACT. The expression of TSPO, STAR, CYP11B1, CYP21A1, and HSD3B1 in adult ACC was significantly lower than in ACA (p<0.05). Regarding pediatric ACT, the expression of genes involved in steroidogenesis was not different between ACA and ACC. Inhibition of isoprenoid production significantly decreased the viability of NCI-H295A cells (p<0.05). However, cholesterol synthesis blockage did not show the same effect on cell viability. Low expression of TSPO ,: StAR, CYP11B1, CYP21A1, and HSD3B1 characterized a signature of adult ACCs. Our data suggest that HMGCR overexpression in adult ACC might lead to intracellular isoprenoid accumulation and cell proliferation. Therefore, the mevalonate pathway is a potential target for ACC treatment.

Metastatic status of sentinel lymph nodes in breast cancer determined with photoacoustic microscopy via dual-targeting nanoparticles

Detection of sentinel lymph nodes (SLNs) is critical to guide the treatment of breast cancer. However, distinguishing metastatic SLNs from normal and inflamed lymph nodes (LNs) during surgical resection remains a challenge. Here, we report a CD44 and scavenger receptor class B1 dual-targeting hyaluronic acid nanoparticle (5K-HA-HPPS) loaded with the near-infra-red fluorescent dye DiR-BOA for SLN imaging in breast cancer. The small sized (~40 nm) self-assembled 5K-HA-HPPSs accumulated rapidly in the SLNs after intradermal injection. Compared with normal popliteal LNs (N-LN), there were ~3.2-fold and ~2.4-fold increases in fluorescence intensity in tumour metastatic SLNs (T-MLN) and inflamed LNs (Inf-LN), respectively, 6 h after nanoparticle inoculation. More importantly, photoacoustic microscopy (PAM) of 5K-HA-HPPS showed a significantly distinct distribution in T-MLN compared with N-LN and Inf-LN. Signals were mainly distributed at the centre of T-MLN but at the periphery of N-LN and Inf-LN. The ratio of PA intensity (R) at the centre of the LNs compared with that at the periphery was 5.93 ± 0.75 for T-MLNs of the 5K-HA-HPPS group, which was much higher than that for the Inf-LNs (R = 0.2 ± 0.07) and N-LNs (R = 0.45 ± 0.09). These results suggest that 5K-HA-HPPS injection combined with PAM provides a powerful tool for distinguishing metastatic SLNs from pLNs and inflamed LNs, thus guiding the removal of SLNs during breast cancer surgery.

Effect of miR-125a-5p targeting Scarb1 gene on hypoxia/reoxygenation injury of cardiomyocytes and its mechanism

To explore the effect and mechanism of miR-125a-5p targeted regulation of scavenger receptor B1 (Scarb1) gene on anoxia/reoxygenation injury of rat cardiomyocytes. H9c2 rat cardiomyocytes were randomly divided into blank control group, hypoxia/reoxygenation group, transfection control group and mir-125a-5p transfection group. The expression of miR-125a-5p, cardiomyocyte viability, apoptosis rate, ATP content and the expression of Scarb1, Cyt C, Bax, Bcl-2 and NF-κB signaling pathway related proteins were determined. Target gene of miR-125a-5p was predicted with Targetscan software, and the targeting of miR-125a-5p on Scarb1 was verified by double luciferase reporter gene experiment. Compared with the blank control group, the expression of miR-125a-5p, Bax, Cyt C and the apoptotic rate of cardiomyocytes in the hypoxia/reoxygenation group were significantly increased (P<0.05), while the expression of Scarb1, Bcl-2 and the content of ATP were significantly decreased (P<0.05). Compared with the control group, the situation of mir-125a-5p transfection group was just the opposite. Double luciferase reporter gene experiment has confirmed Scarb1 to be the target of miR-125a-5p. Hypoxia/reoxygenation can promote the expression of NF-κB p65, C-myc and Cyclin D1 in cardiomyocytes, while down-regulating the expression of miR-125a-5p can inhibit the expression of such proteins. Hypoxia/reoxygenation can induce the expression of miR-125a-5p in rat cardiomyocytes. Inhibition of miR-125a-5p can protect cardiomyocytes from hypoxia/reoxygenation by up-regulating the expression of Scarb1. The mechanism may be related to the inhibition of activation of NF-κB signaling pathway.

Identification of scavenger receptor BI as a potential screening candidate for congenital primary adrenal insufficiency in humans.

Glucocorticoids belong to the superfamily of steroid hormones that are synthesized from the common precursor cholesterol. Adrenal gland-derived glucocorticoids, e.g., cortisol in humans and corticosterone in rodents, contribute to various processes essential for normal daily life. Glucocorticoid deficiency, also referred to as primary adrenal insufficiency, therefore, often becomes evident early in life and can be present with hypoglycemia, a failure to thrive, recurrent development of infections, and neurological problems, such as seizures and coma. The majority of congenital primary adrenal insufficiency cases are caused by deleterious mutations in genes involved in the intracellular mobilization of cholesterol and the subsequent conversion of cholesterol into glucocorticoids. A significant number of glucocorticoid deficiency cases, however, cannot be explained by known genetic variations. This perspective highlights existing literature regarding the importance of lipoprotein-derived cholesterol acquisition through scavenger receptor class B, type I (SR-BI/SCARB1) for the maintenance of an optimal adrenal glucocorticoid function in mice and humans. On the basis of the reviewed findings, it is suggested that the SCARB1 gene should be included in the standard glucocorticoid deficiency genetic screening panel to 1) facilitate knowledge development on the relative contribution of SR-BI-mediated cholesterol acquisition to steroid hormone synthesis in humans and 2) open up the possibility to reclassify glucocorticoid deficiency patients without a currently known genetic cause for concomitant treatment optimization.

Being red, blue and green: the genetic basis of coloration differences in the strawberry poison frog (Oophaga pumilio)

BackgroundAnimal coloration is usually an adaptive attribute, under strong local selection pressures and often diversified among species or populations. The strawberry poison frog (Oophaga pumilio) shows an impressive array of color morphs across its distribution in Central America. Here we quantify gene expression and genetic variation to identify candidate genes involved in generating divergence in coloration between populations of red, green and blue O. pumilio from the Bocas del Toro archipelago in Panama.ResultsWe generated a high quality non-redundant reference transcriptome by mapping the products of genome-guided and de novo transcriptome assemblies onto a re-scaffolded draft genome of O. pumilio. We then measured gene expression in individuals of the three color phenotypes and identified color-associated candidate genes by comparing differential expression results against a list of a priori gene sets for five different functional categories of coloration – pteridine synthesis, carotenoid synthesis, melanin synthesis, iridophore pathways (structural coloration), and chromatophore development. We found 68 candidate coloration loci with significant expression differences among the color phenotypes. Notable upregulated examples include pteridine synthesis genes spr, xdh and pts (in red and green frogs); carotenoid metabolism genes bco2 (in blue frogs), scarb1 (in red frogs), and guanine metabolism gene psat1 (in blue frogs). We detected significantly higher expression of the pteridine synthesis gene set in red and green frogs versus blue frogs. In addition to gene expression differences, we identified 370 outlier SNPs on 162 annotated genes showing signatures of diversifying selection, including eight pigmentation-associated genes.ConclusionsGene expression in the skin of the three populations of frogs with differing coloration is highly divergent. The strong signal of differential expression in pteridine genes is consistent with a major role of these genes in generating the coloration differences among the three morphs. However, the finding of differentially expressed genes across pathways and functional categories suggests that multiple mechanisms are responsible for the coloration differences, likely involving both pigmentary and structural coloration. In addition to regulatory differences, we found potential evidence of differential selection acting at the protein sequence level in several color-associated loci, which could contribute to the color polymorphism.

Molecular mechanisms of the cytoprotector cramizol effect in the experimental dyslipidemia model

The tested drug cramizol exhibits lipid-lowering and anti-atherogenic effects. Cramizol reduces blood cholesterol and triglycerides. It also increases HDL and reduces the atherogenic index in rats with the chronic dyslipidemia model induced by a hypercholesterol diet. Cramizol is effective as a hypolipidemic agent and its efficiency is comparable with the reference drug, phenofibrate. Cramizol increases expression of the ApoA1 and ApoC2 genes, and also reduces expression of the Scarb1 gene in rats with experimentally induced hyperlipidemia. These mechanisms could be the basis of its hypolipidemic and anti-atherogenic actions.

Hepatitis C Virus Infection of Human Thyrocytes: Metabolic, Hormonal, and Immunological Implications.

Hepatitis C virus (HCV) infection is a prevalent disease worldwide. Thyroid dysfunction is one of the most common extrahepatic manifestations of HCV infection. We hypothesized that HCV can directly infect human thyrocytes thereby causing thyroid dysfunction. Human thyrocytes in primary cell culture, ML-1 human thyroid cell line, and Huh7.5 human hepatocyte cell line were infected with HCV using the Huh7.5JFH1 cell line that releases infectious HCV virions. After infection, the release of new virions, production of proinflammatory cytokines, and expression of miR-122 were evaluated. Ribonucleic acid (RNA) extracted from HCV-infected cells and mock-infected cells was subjected to RNA sequencing and transcriptomic analysis. Ingenuity pathway analysis was used to detect up- and down-regulated pathways. Human thyrocytes express major HCV entry factors including CD81, occludin, claudin-1, and scavenger receptor class B1. Viral infection of thyroid cells was confirmed by detection of HCV core protein in supernatants and negative-sense HCV RNA in cell lysates. HCV infection of thyrocytes induced the production of the chemokine CXCL-8 and the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and significantly increased the expression of miR-122. Moreover, HCV infection of thyrocytes decreased expression of the thyroid peroxidase and thyroglobulin genes and increased expression of the deiodinase 2 gene. The top upregulated pathways in HCV-infected thyrocytes were immune pathways and metabolic pathways, while infected hepatocytes upregulated lipid and glucose metabolism pathways as previously reported. HCV infection may induce thyroid dysfunction by different mechanisms including direct infection of thyrocytes leading to activation of inflammatory pathways and upregulation of miR-122. These findings support a general mechanism for viral induction of autoimmunity through direct infection of target tissues.

Paraquat exposure delays late-stage Leydig cell differentiation in rats during puberty

Paraquat is a fast and non-selective herbicide that is widely used in crop cultivation and conservation tillage systems. Animal experiments have shown that paraquat decreases sperm quality and testicular organ coefficient, but its effects on the development of Leydig cells remain unclear. The objective of the current study was to investigate the effects of paraquat exposure on the Leydig cell development in rats during puberty. Twenty-eight male 35-day-old Sprague-Dawley rats were divided into 4 groups: 0, 0.5, 2.0, and 8 mg kg−1 d−1 paraquat. Paraquat was gavaged for 10 d. Adult Leydig cells were isolated and treated with paraquat for 24 h. Paraquat in vivo significantly decreased body and testis weights at 8 mg kg−1 and lowered serum testosterone levels at 2 and 8 mg kg−1 without affecting the levels of serum luteinizing hormone and follicle-stimulating hormone. Paraquat did not alter Leydig cell number and PCNA labeling index. Real-time PCR showed that paraquat down-regulated the expression of Lhcgr, Scarb1, Cyp11a1, Cyp17a1, and Hsd17b3 genes and their proteins at 2 or 8 mg kg−1, while it up-regulated the expression of Srd5a1 at 8 mg kg−1. Paraquat increased ROS and decreased testosterone production by Leydig cells at 1 and 10 μM after in vitro 24-h exposure. Vitamin E (40 μg/ml) reversed paraquat-induced ROS and suppression of testosterone synthesis in vitro. In conclusion, paraquat directly delays Leydig cell differentiation to block testosterone synthesis via down-regulating the expression of critical testosterone synthesis-related genes and up-regulating the expression of testosterone metabolic enzyme (Srd5a1) gene and possibly via increasing ROS production.

Rare P376L variant in the SR-BI gene associates with HDL dysfunction and risk of cardiovascular disease

BackgroundScavenger receptor class B type 1 (SR-BI) encoded by SCARB1 gene serves as a multifunctional HDL receptor, facilitating the uptake of cholesteryl esters from HDL to the liver. Recent studies have identified the association between the P376L missense mutation of the SCARB1 gene with increased serum HDL-Cholesterol level. However, the contribution of this variant to the development of cardiovascular disease (CVD) remains unclear. ObjectiveWe have investigated the association between the P376L polymorphism with the properties of HDL and CVD outcomes in a population sample recruited as part of the Mashhad-Stroke and Heart-Atherosclerotic-Disorders (MASHAD) cohort. MethodsSix hundred and fifteen individuals who had a median follow-up period of 7 years were recruited as part of the MASHAD cohort. Anthropometric, biochemical parameters and HDL lipid peroxidation (HDLox) were assessed. Genotyping was performed using TaqMan-real-time-PCR based method. The association of P376L-rs74830766 with cardiovascular-risk-factors and CVD events were evaluated. ResultsCarriers of the P376L variant were significantly more likely than non-carriers to develop CVD using multivariate analyses adjusted for traditional CVD risk factors defined as: age, sex, BMI, presence of diabetes, or hypertension, positive smoking habit, and total cholesterol (OR: 3.75, 95%CI: 1.76–7.98, p = 0.001). In an adjusted model, there was a two fold increase in cardiovascular endpoints among individuals who were heterozygous for the P376L variant (hazard ratio, 2.08; 95% CI, 1.12-to 3.84, p = 0.02). Although there was no association between the presence of the P376L variant and HDL-C level, serum HDLox, measured as dysfunctional HDL, was 13% higher among carriers of the P376L variant than non-carriers. ConclusionWe have found that carriers of the P376L variant possessed higher HDLox and were at increased risk of CVD in a representative population-based cohort, as compared to non-carriers.

Dexamethasone suppresses the differentiation of stem Leydig cells in rats in vitro

BackgroundIt is an established fact that excess of glucocorticoids could cause the harmful effects, such as suppression on the male reproduction. Although glucocorticoids pharmacologically inhibit the Leydig cell function, their roles in Leydig cell development are unclear. Therefore, the present study was designed to investigate effects of synthetic glucocorticoid dexamethasone (DEX) on rat stem Leydig cell proliferation and differentiation.MethodsMale Sprague-Dawley rats received a single intraperitoneal injection of 75 mg/kg EDS to eliminate Leydig cells and an in vitro culture system of the seminiferous tubules was established from Leydig cell-depleted testis. Using basal medium and Leydig cell differentiation-inducing medium (LIM) in the culture system, we examined the effects of DEX (0–100 nM) on the proliferation and differentiation of the stem Leydig cells in vitro, respectively.ResultsResults showed that LIM is a good agent to induce stem Leydig cell differentiation into Leydig cells that produce testosterone in vitro. DEX inhibited the differentiation of stem Leydig cells by reducing the expression levels of Cyp17a1 and Scarb1 and that NR3C1 antagonist RU38486 reversed the DEX-mediated effects. However, DEX are not involved with the proliferation of stem Leydig cells.ConclusionsDEX suppressed the differentiation of rat Leydig cells in vitro and glucocorticoid-induced effects acted through NR3C1. This suppression partially targets on Cyp17a1 and Scarb1 gene expression.

Lipid-lowering effect of Phyllanthus embilica and Alpinia galanga extracts on HepG2 cell line

Dyslipidemia is a key risk factor for cardiovascular diseases. Although statins are powerful therapeutic option for achieving target low- and high-density lipoprotein levels, it is of interest to seek for alternative treatments for dyslipidemia. Phyllanthus emblica and Alpinia galanga were found to have hypolipidemic effects. However, the mechanisms underlying their bioactivity have not yet been elucidated. Lipid-lowering effects of the hydroethanolic extracts from a Phyllanthus emblica (PE), Alpinia galangal (AG) and a combination between P. emblica and A. galangal (PEAG; ratio 7:3 w/w) on expression of low-density lipoprotein receptor (LDLR), 3-hydroxyl-3-methylglutaryl-CoA reductase (HMGCR), apolipoprotein A1 (ApoA1) and scavenger receptor class B1 (SR-BI) genes were assessed in HepG2 cell line using quantitative RT-PCR (qRT-PCR). It was demonstrated from the MTT cytotoxic assay that PE and PEAG were not cytotoxic to HepG2 cell line. AG, gallic acid and simvastatin were more cytotoxic to HepG2 cell line. PEAG was found to be the most promising therapeutic agent for clearance of circulating LDL-C due to its enhancing expression of the LDLR gene. It could contribute towards enhancement of the HDL-C levels due to its upregulation expression of the APOA1 and SR-B1 mRNA transcripts in HepG2 cells.

Shear stress regulates eNOS signaling in human umbilical vein endothelial cells via SRB1-PI3KAP1 pathway

Background: The occurrence and development of atherosclerosis are closely related to shear stress on the endothelial cells. However, related molecular mechanisms of controlling mechanical signal transduction in endothelial cells remain largely unknown. Aim of the Study: To obtain this goal, here, a parallel-plate flow chamber was used to impose laminar shear stress (8.4 dyne/cm2 ) on endothelial cells for 0 minute (min), 10 min, 30 min, 60 min, and 120 min. Subjects and Methods: The RNA interference was employed to down-regulate scavenger receptor class B1 (SRB1) and LY294002 was performed to block the phosphorylation status of the phosphoinositide 3-kinase pathway. Then, the cell status was observed under the microscope, followed by detection of phosphorylated phosphoinositide 3-kinase (PI3K), p38, extracellular signal-regulated protein kinases 1 and 2 and the binding activities of activator protein 1, nuclear factorκB and endothelial nitric oxide synthase (eNOs) by western blot. The results showed that shear stress (8.4 dyne/cm2 ) for 60 min induced obvious cell morphologic changes. Meanwhile, PI3K phosphorylation and eNOS expression were significantly increased by shear stress while reversed by SRB1 si-RNA and LY294002. Additionally, shear stress caused the enhanced binding activity of nuclear transcription factor activator protein 1 (AP-1) to DNA from 10 to 120 min, while only at 30 and 60 min for NF-κB. After treatment with SRB1 si-RNA and LY294002 inhibitor, the binding activities of AP-1 and DNA was significantly decreased, however, there was no effect on NF-κB binding activity. Results: Therefore, SRB1 plays a crucial role in mediating shear stress-induced eNOS activation in endothelial cells via PI3K-AP1 pathway. These findings will provide an important understanding of shear stress-induced cell alterations in clinic detection

Unusual genetic variants associated with hypercholesterolemia in Argentina

Background and aimsMarked hypercholesterolemia, defined as low density lipoprotein cholesterol (LDL-C) levels ≥ 190 mg/dL, may be due to LDLR, APOB, and PCSK9 variants. In a recent analysis, only 1.7% of cases had such variants. Our goal was to identify other potential genetic causes of hypercholesterolemia. MethodsIn a total of 51,253 subjects with lipid testing, 3.8% had elevated total cholesterol >300 mg/dL and/or LDL-C≥190 mg/dL. Of these, 246 were further studied, and 69 without kidney, liver, or thyroid disease and who met Dutch Lipid Clinic Network criteria of ≥6 points had DNA sequencing done at the LDLR, APOB, PCSK9, APOE, LDLRAP1, STAP1, ABCG5, ABCG8, CYP27A1, LIPA, LIPC, LIPG, LPL, and SCARB1 gene loci and also had 10 SNP analysis for a weighted high LDL-C genetic risk score. ResultsIn the 69 subjects with genetic analyses, the following variants were observed in 37 subjects (53.6%): LDLR (n = 20, 2 novel), ABCG5/8 (n = 7, 2 novel), APOB (n = 3, 1 novel), CYP27A1 (n = 3, 1 novel), LIPA (n = 2, 1 novel), APOE (n = 2), LIPC (n = 1, novel), LIPG (n = 1, novel), and SCARB1 (n = 1); 14 subjects (20.3%) had a high polygenic score, with 4 (5.8%) having no variants. ConclusionsOur data indicate that in addition to variants in LDLR, APOB, PCSK9, APOE, LDLRAP1, and STAP1, variants in ABCG5/8, CYP27A1, LIPA, LIPC, and LIPG may be associated with hypercholesterolemia and such information should be used to optimize therapy.

P6271Variants of CETP, LIPC, and SCARB1 genes in Korean patients with very high HDL-cholesterol levels

P6271Variants of CETP, LIPC, and SCARB1 genes in Korean patients with very high HDL-cholesterol levels

MicroRNA-21 and microRNA-214 play important role in reproduction regulation during porcine estrous.

Normal estrous cycle is crucial for porcine reproduction, and microRNA is closely related to regulation of estrous cycle in porcine ovaries. In this study, we found that the expression of miR-214 in porcine ovaries was higher than in many other tissues, and miR-21 expression in ovaries was significantly higher than in the uterus and pituitary. Meanwhile, miR-21 was upregulated and miR-214 was downregulated in the ovaries of high litter size (YH) pigs compared with low litter size (YL) pigs. Moreover, the lowest expression of miR-21 and miR-214 occurred on Days 14 and 7 of the estrous cycle and was expressed at greater levels in the granulosa cells of subordinate follicles than in dominant follicles on Day 3 of the estrous cycle. Bioinformatics analysis showed that miR-21 and miR-214 might target several genes that involved in the mTOR signaling, apoptosis, and steroid biosynthesis pathways, and they play important roles in maintaining the porcine estrous cycle. The qPCR and western blot analysis indicated that miR-214 inhibited the expression of SCARB1 gene in the transcriptional level, but not affected the SCARB1 gene's protein level. Our research findings indicated that miR-21 and miR-214 played important roles in reproduction regulation during porcine estrous.