EEPD1 Is a Novel LXR Target Gene in Macrophages Which Regulates ABCA1 Abundance and Cholesterol Efflux

Dysregulated lipid metabolism networks modulate T-cell function in people with relapsing-remitting multiple sclerosis

Altered cholesterol, oxysterol, sphingolipid, and fatty acid concentrations are reported in blood, cerebrospinal fluid, and brain tissue of people with relapsing-remitting multiple sclerosis (RRMS) and are linked to disease progression and treatment responses. CD4 + T cells are pathogenic in RRMS, and defective T-cell function could be mediated in part by liver X receptors (LXRs)-nuclear receptors that regulate lipid homeostasis and immunity. RNA-sequencing and pathway analysis identified that genes within the 'lipid metabolism' and 'signalling of nuclear receptors' pathways were dysregulated in CD4 + T cells isolated from RRMS patients compared with healthy donors. While LXRB and genes associated with cholesterol metabolism were upregulated, other T-cell LXR-target genes, including genes involved in cellular lipid uptake (inducible degrader of the LDL receptor, IDOL), and the rate-limiting enzyme for glycosphingolipid biosynthesis (UDP-glucosylceramide synthase, UGCG) were downregulated in T cells from patients with RRMS compared to healthy donors. Correspondingly, plasma membrane glycosphingolipids were reduced, and cholesterol levels increased in RRMS CD4 + T cells, an effect partially recapitulated in healthy T cells by in vitro culture with T-cell receptor stimulation in the presence of serum from RRMS patients. Notably, stimulation with LXR-agonist GW3965 normalized membrane cholesterol levels, and reduced proliferation and IL17 cytokine production in RRMS CD4 + T-cells. Thus, LXR-mediated lipid metabolism pathways were dysregulated in T cells from patients with RRMS and could contribute to RRMS pathogenesis. Therapies that modify lipid metabolism could help restore immune cell function.

Non-Alcoholic Fatty Liver Disease Induced by Feeding Medium-Chain Fatty Acids Upregulates Cholesterol and Lipid Homeostatic Genes in Skeletal Muscle of Neonatal Pigs

Non-alcoholic fatty liver disease (NAFLD) is a range of disorders characterized by lipid accumulation in hepatocytes. Although this spectrum of disorders is associated with adult obesity, recent evidence suggests that this condition could also occur independently of obesity, even in children. Previously, we reported that pigs fed a formula containing medium-chain fatty acids (MCFAs) developed hepatic steatosis and weighed less than those fed an isocaloric formula containing long-chain fatty acids (LCFAs). Our objective was to determine the association between NAFLD and the skeletal muscle transcriptome in response to energy and lipid intake. Neonatal pigs were fed one of three formulas: a control formula (CONT, n = 6) or one of two isocaloric high-energy formulas containing either long (LCFA, n = 6) or medium (MCFA, n = 6) chain fatty acids. Pigs were fed for 22 d, and tissues were collected. Body weight at 20 and 22 d was greater for LCFA-fed pigs than their CONT or MCFA counterparts (p < 0.005). Longissimus dorsi weight was greater for LCFA compared with MCFA, while CONT was intermediate (p < 0.05). Lean gain and protein deposition were greater for LCFA than for CONT and MCFA groups (p < 0.01). Transcriptomic analysis revealed 36 differentially expressed genes (DEGs) between MCFA and LCFA, 53 DEGs between MCFA and CONT, and 52 DEGs between LCFA and CONT (FDR < 0.2). Feeding formula high in MCFAs resulted in lower body and muscle weights. Transcriptomics data suggest that the reduction in growth was associated with a disruption in cholesterol metabolism in skeletal muscles.

TRIM21-mediated Sohlh2 ubiquitination suppresses M2 macrophage polarization and progression of triple-negative breast cancer

Lung metastasis is the major cause of death in patients with triple-negative breast cancer (TNBC). Tumor-associated macrophages (TAMs) represent the M2-like phenotype with potent immunosuppressive activity, and play a pro-tumor role in TNBC lung metastasis. Sohlh2 belongs to the basic helix-loop-helix transcription factor family. However, its role in macrophages polarization remains unknown, especially in TNBC progression. Here we demonstrated that Sohlh2 overexpression promoted M2 macrophage polarization. Moreover, high expression of Sohlh2 in M2-like macrophage enhanced TNBC cell growth, migration and lung metastasis in vivo and in vitro. Mechanistically, we revealed that Sohlh2 functioned through up-regulating LXRα, ABCA1, ABCG1 expression and disturbing the lipid homeostasis on the membrane of macrophages. Sohlh2 could directly bind to the promoter of LXRα and promote its transcription activity. E3 ubiquitin ligase TRIM21 promoted Sohlh2 ubiquitination and degradation, and suppressed M2 macrophage polarization and TNBC progression. Collectively, our findings suggested that Sohlh2 in macrophage could be a novel therapeutic target for TNBC metastatic treatment.

iTRAQ-Based Quantitative Proteomic Analysis of Arthrobacter simplex in Response to Cortisone Acetate and Its Mutants with Improved Δ1-Dehydrogenation Efficiency

Arthrobacter simplex is extensively used for cortisone acetate (CA) biotransformation in industry, but the Δ¹-dehydrogenation molecular fundamental remains unclear. Herein, the comparative proteome revealed several proteins with the potential role in this reaction, which were mainly involved in lipid or amino acid transport and metabolism, energy production and conversion, steroid degradation, and transporter. The influences of six proteins were further confirmed, where pps, MceG_A, yrbE4A_A, yrbE4B_A, and hyp2 showed positive impacts, while hyp1 exhibited a negative effect. Additionally, KsdD5 behaved as the best catalytic enzyme. By the combined manipulation in multiple genes under the control of a stronger promoter, an optimal strain with better catalytic enzyme activity, substrate transportation, and cell stress tolerance was created. After biotechnology optimization, the production peak and productivity were, respectively, boosted by 4.1- and 4.0-fold relative to the initial level. Our work broadens the understanding of the Δ¹-dehydrogenation mechanism, also providing effective strategies for excellent steroid-transforming strains.

Sterol-regulated transmembrane protein TMEM86a couples LXR signaling to regulation of lysoplasmalogens in macrophages

Lysoplasmalogens are a class of vinyl ether bioactive lipids that have a central role in plasmalogen metabolism and membrane fluidity. The liver X receptor (LXR) transcription factors are important determinants of cellular lipid homeostasis owing to their ability to regulate cholesterol and fatty acid metabolism. However, their role in governing the composition of lipid species such as lysoplasmalogens in cellular membranes is less well studied. Here, we mapped the lipidome of bone marrow-derived macrophages (BMDMs) following LXR activation. We found a marked reduction in the levels of lysoplasmalogen species in the absence of changes in the levels of plasmalogens themselves. Transcriptional profiling of LXR-activated macrophages identified the gene encoding transmembrane protein 86a (TMEM86a), an integral endoplasmic reticulum protein, as a previously uncharacterized sterol-regulated gene. We demonstrate that TMEM86a is a direct transcriptional target of LXR in macrophages and microglia and that it is highly expressed in TREM2+/lipid-associated macrophages in human atherosclerotic plaques, where its expression positively correlates with other LXR-regulated genes. We further show that both murine and human TMEM86a display active lysoplasmalogenase activity that can be abrogated by inactivating mutations in the predicted catalytic site. Consequently, we demonstrate that overexpression of Tmem86a in BMDM markedly reduces lysoplasmalogen abundance and membrane fluidity, while reciprocally, silencing of Tmem86a increases basal lysoplasmalogen levels and abrogates the LXR-dependent reduction of this lipid species. Collectively, our findings implicate TMEM86a as a sterol-regulated lysoplasmalogenase in macrophages that contributes to sterol-dependent membrane remodeling.

Cyclodextrin-mediated conjugation of macrophage and liposomes for treatment of atherosclerosis

Current pharmacological treatments of atherosclerosis often target either cholesterol management or inflammation management, to inhibit atherosclerotic progression, but cannot lead to direct plaque lysis and atherosclerotic regression, partly due to the poor accumulation of medicine in the atherosclerotic plaques. Due to enhanced macrophage recruitment during atheromatous plaque progression, a facilely macrophage-liposome conjugate was constructed for targeted anti-atherosclerosis therapy via synergistic plaque lysis and inflammation alleviation. Endogenous macrophage is utilized as drug-transporting cell, upon membrane-modification with β-cyclodextrin (β-CD) derivative to form β-CD decorated macrophage (CD-MP). Adamantane (ADA) modified quercetin (QT)-loaded liposome (QT-NP), can be conjugated to CD-MP via host-guest interactions between β-CD and ADA to construct macrophage-liposome conjugate (MP-QT-NP). Thus, macrophage carries liposome "hand-in-hand" to significantly increase the accumulation of anchored QT-NP in the aorta plaque in response to the plaque inflammation. In addition to anti-inflammation effects of QT, MP-QT-NP efficiently regresses atherosclerotic plaques from both murine aorta and human carotid arteries via CD-MP mediated cholesterol efflux, due to the binding of cholesterol by excess membrane β-CD. Transcriptome analysis of atherosclerotic murine aorta and human carotid tissues reveal that MP-QT-NP may activate NRF2 pathway to inhibit plaque inflammation, and simultaneously upregulate liver X receptor to promote cholesterol efflux.

Genomic Variants and Multilevel Regulation of ABCA1, ABCG1, and SCARB1 Expression in Atherogenesis

Atheroprotective properties of human plasma high-density lipoproteins (HDLs) are determined by their involvement in reverse cholesterol transport (RCT) from the macrophage to the liver. ABCA1, ABCG1, and SR-BI cholesterol transporters are involved in cholesterol efflux from macrophages to lipid-free ApoA-I and HDL as a first RCT step. Molecular determinants of RCT efficiency that may possess diagnostic and therapeutic meaning remain largely unknown. This review summarizes the progress in studying the genomic variants of ABCA1, ABCG1, and SCARB1, and the regulation of their function at transcriptional and post-transcriptional levels in atherosclerosis. Defects in the structure and function of ABCA1, ABCG1, and SR-BI are caused by changes in the gene sequence, such as single nucleotide polymorphism or various mutations. In the transcription initiation of transporter genes, in addition to transcription factors, long noncoding RNA (lncRNA), transcription activators, and repressors are also involved. Furthermore, transcription is substantially influenced by the methylation of gene promoter regions. Post-transcriptional regulation involves microRNAs and lncRNAs, including circular RNAs. The potential biomarkers and targets for atheroprotection, based on molecular mechanisms of expression regulation for three transporter genes, are also discussed in this review.

Interaction of porcine circovirus-like virus P1 capsid protein with host proteins

Background

Porcine circovirus-like virus P1 is a relatively new kind of virus that is closely related to the post-weaning multisystemic wasting syndrome, congenital tremors, and abortions in swine. The molecular mechanisms of P1 virus infection and pathogenesis are fully unknown. To analyze P1 and its host interactions, we used a yeast two-hybrid (Y2H) assay to identify cellular proteins interacting with the Cap of the P1 virus. In this study, the Cap of the P1 virus exhibited no self-activation and toxicity to yeast cells and was used as bait to screen the Y2H library prepared from the pancreas tissue.

Results

Five cellular proteins (EEP, Ral GDS, Bcl-2-L-12, CPS1, and one not identified) were found to interact with P1 Cap. The interaction between Cap and Ral GDS was confirmed by co-immunoprecipitation.

Conclusions

Our data are likely to support the future investigation of the underlying mechanism of P1 infection and pathogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02926-6.

Myocardin suppression increases lipid retention and atherosclerosis via downregulation of ABCA1 in vascular smooth muscle cells

Myocardin (MYOCD) plays an important role in cardiovascular disease. However, its underlying impact on atherosclerosis remains to be elucidated. ATP binding cassette transporter A1 (ABCA1), a key membrane-associated lipid transporter which maintains intracellular lipid homeostasis, has a protective function in atherosclerosis progress. The purpose of this study was to investigate whether and how the effect of MYOCD on atherosclerosis is associated with ABCA1 in vascular smooth muscle cells (VSMCs). We found both MYOCD and ABCA1 expression were dramatically decreased in atherosclerotic patient aortas compared to control. MYOCD knockdown inhibited ABCA1 expression in human aortic vascular smooth muscle cells (HAVSMCs), leading to reduced cholesterol efflux and increased intracellular cholesterol contents. MYOCD overexpression exerted the opposite effect. Mechanistically, MYOCD regulates ABCA1 expression in an SRF-dependent manner. Consistently, apolipoprotein E-deficient mice treated with MYOCD shRNA developed more plaques in the aortic sinus, which is associated with reduced ABCA1 expression, increased cholesterol retention in the aorta, and decreased high-density lipoprotein cholesterol levels in the plasma. Our data suggest that MYOCD deficiency exacerbates atherosclerosis by downregulating ABCA1 dependent cholesterol efflux from VSMCs, thereby providing a novel strategy for the therapeutic treatment of atherosclerotic cardiovascular disease.

CTRP9 alleviates foam cells apoptosis by enhancing cholesterol efflux

The apoptosis of foam cells leads to instability of atherosclerotic plaques. This study was designed to explore the protective role of CTRP9 in foam cell apoptosis. In our experiment, CTRP9 alleviated foam cell apoptosis. Meanwhile, CTRP9 upregulated the expression of proteins important for cholesterol efflux, such as LXRα, CYP27A1, ABCG1 and ABCA1, and improved cholesterol efflux in foam cells. Moreover, CTRP9 inhibited Wnt3a and β-catenin expression and β-catenin nuclear translocation in foam cells. In addition, adenovirus overexpression of Wnt3a abolished the effect of CTRP9 on macrophage apoptosis. Mechanistically, the AMPK inhibitor abolished the effect of CTRP9 on foam cell apoptosis, and downregulation of AdipoR1 by siRNA abrogated the activation of AMPK and the effect of CTRP9 on foam cell apoptosis. We concluded that CTRP9 achieved these protective effects on foam cells through the AdipoR1/AMPK pathway.

MicroRNA-320b Modulates Cholesterol Efflux and Atherosclerosis

Aim: ATP-binding cassette (ABC) transporters and endonuclease-exonuclease-phosphatase family domain containing 1 (EEPD1) are reported to regulate cellular cholesterol efflux in macrophages. Bioinformatics analysis has revealed that ABCG1 and EEPD1 might be potential targets of microRNA (miR)-320b. This study aimed to elucidate the roles of miR-320b in cholesterol efflux from macrophages and the pathogenesis of atherosclerosis.

Methods: Microarray was conducted to profile microRNA (miRNA) expression, and quantitative real-time PCR (qPCR) was used to validate the differentially expressed miRNAs in peripheral blood mononuclear cells of coronary artery disease (CAD) patients and healthy controls. Luciferase assay was conducted to evaluate the activity of reporter construct containing the 3´-untranslated region (3´-UTR) of target genes. Besides, NBD-cholesterol efflux induced by high-density lipoprotein (HDL) and lipid-free apolipoprotein A1 (apoA1) was detected using fluorescence intensity, respectively. Apoe^−/− mice were injected with adeno-associated virus (AAV)2-miR-320b or control via tail vein, thereafter fed with 14 week atherogenic diet to study the roles of miR-320b in vivo .

Results: MiR-320b was highly expressed in CAD patients compared with that in the healthy controls in both the microarray analysis and qPCR analysis. In vitro study showed that miR-320b decreased HDL- and apoA1-mediated cholesterol efflux from macrophages partly by directly targeting ABCG1 and EEPD1 genes and partly via suppressing the LXRα-ABCA1/G1 pathway. Consistently, in vivo administration of AAV2-miR-320b into Apoe^−/− mice attenuated cholesterol efflux from peritoneal macrophages, which showed reduced expression of ABCA1/G1 and EEPD1, and increased lipid LDL-C level, with a down-regulation of hepatic LDLR and ABCA1. AAV2-miR-320b treatment also increased atherosclerotic plaque size and lesional macrophage content and enhanced pro-inflammatory cytokines levels through the elevated phosphorylation level of nuclear factor-κB p65 in macrophages.

Conclusion: We identify miR-320b as a novel modulator of macrophage cholesterol efflux and that it might be a promising therapeutic target for atherosclerosis treatment.

Astragalin Retards Atherosclerosis by Promoting Cholesterol Efflux and Inhibiting the Inflammatory Response via Upregulating ABCA1 and ABCG1 Expression in Macrophages

ABSTRACT

Lipid metabolism disorder and inflammatory response are considered to be the major causes of atherosclerogenesis. Astragalin, the most important functional component of flavonoid obtained from persimmon leaves, has the hypolipidemic effects. However, it is unknown, how astragalin protects against atherosclerosis. The aim of this study was to observe the effects of astragalin on cholesterol efflux and inflammatory response and to explore the underlying mechanisms. Our results showed that astragalin upregulated the expression of ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1), promoted cholesterol efflux, and suppressed foam cell formation. Inhibition of the PPARγ/LXRα pathway abrogated the promotive effects of astragalin on both transporter expression and cholesterol efflux. In addition, treatment of astragalin markedly decreased the secretion of inflammatory factors, including interleukin 6, monocyte chemotactic protein 1, tumor necrosis factor α, and interleukin 1β. Mechanistically, astragalin upregulated ABCA1 and ABCG1 expression, which in turn reduced TLR4 surface levels and inhibited NF-κB nuclear translocation. Consistently, astragalin reduced atherosclerotic plaque area in apoE-/- mice. Taken together, these findings suggest that astragalin protects against atherosclerosis by promoting ABCA1- and ABCG1-mediated cholesterol efflux and inhibiting proinflammatory mediator release.

ABCA1 plays an anti-inflammatory role by affecting TLR4 at the feto-maternal interface

AIMS

This study aimed to evaluate the function and pathway of ATP-binding cassette transporter member A1 (ABCA1)-induced anti-inflammatory response in cells at the feto-maternal interface.

MAIN METHODS

The primary amniotic mesenchymal cells (AMCs), chorion cells and decidual cells were isolated from placental membranes of women with uncomplicated pregnancies at full-term (not in labor) using enzymatic digestion. Flow cytometry was used to measure the purity of isolated cells. Immunofluorescence assay was performed to detect the location of ABCA1 and toll-like receptor 4 (TLR4). Reverse transcription PCR and western blotting analyses were used to examine ABCA1, TLR4 and inflammatory factor expression in primary cells. ELISA was used to detect cytokine secretions from the primary cells.

KEY FINDINGS

ABCA1 and TLR4 were mainly located in the cell nucleus and cytoplasm of feto-maternal interface cells. ABCA1 expression remained the highest in chorion cells, medium in decidual cells, and weakest in AMCs. Upregulated expression of ABCA1 decreased expression of TLR4 and the levels of pro-inflammatory factors, but increased cytoprotective factors in all cell types. In contrast, downregulated expression of ABCA1 increased the expression of TLR4 and pro-inflammatory factors, but decreased the levels of cytoprotective factors. Downregulated ABCA1 expression followed by decreased TLR4 expression using a small interference RNA (siRNA) induced reduction of interleukin (IL)-1β and tumor necrosis factor-α (TNF-α) in all cell types.

SIGNIFICANCE

ABCA1 at feto-maternal interface acts as an anti-inflammatory role by reducing the expression of TLR4 in uncomplicated pregnancies. ABCA1 might be a potential therapeutic target for preventing gestational diseases.

Transcriptome profiling of longissimus lumborum in Holstein bulls and steers with different beef qualities

Previous research regarding Holstein cows has mainly focused on increasing milk yield. However, in order to maximize the economical profits of Holstein cattle farming, it is necessary to fully take advantage of Holstein bulls to produce high-grade beef. The present study aims to investigate different transcriptomic profiling of Holstein bulls and steers, via high-throughput RNA-sequencing (RNA-seq). The growth and beef quality traits of Holstein steers and bulls were characterized via assessment of weight, rib eye area, marbling score, shear force and intramuscular fat percentage of the longissimus lumborum (LL) muscle. The results indicated that castration improved the meat quality, yet reduced the meat yield. Subsequently, RNA-seq of the LL muscle from Holstein steers and bulls revealed a total of 56 differentially expressed genes (DEGs). We performed the functional enrichment analysis in Gene Ontology (GO) annotations of the DEGs using GOseq R package software and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis using KOBAS tool. Through the integrated analysis of DEGs with reported QTLs and SNPs, seven promising candidate genes potentially affecting the beef quality of LL muscle following castration were discovered, including muscle structural protein coding genes (MYH1, MYH4, MYH10) and functional protein coding genes (GADL1, CYP2R1, EEPD1, SHISA3). Among them, MYH10, GADL1, CYP2R1, EEPD1 and SHISA3 were novel candidate genes associated with beef quality traits. Notably, EEPD1 was associated with both meat quality and reproduction traits, thus indicating its overlapping role in responding to hormone change, and subsequently inducing beef quality improvement. Our findings provide a complete dataset of gene expression profile of LL in Holstein bulls and steers, and will aid in understanding how castration influence meat yield and quality.

Inflammation Triggers Liver X Receptor-Dependent Lipogenesis

Immune cell function can be modulated by changes in lipid metabolism. Our studies indicate that cholesterol and fatty acid synthesis increases in macrophages between 12 and 18 h after the activation of Toll-like receptors with proinflammatory stimuli and that the upregulation of lipogenesis may contribute to the resolution of inflammation. The inflammation-dependent increase in lipogenesis requires the induction of the liver X receptors, members of the nuclear receptor superfamily of transcription factors, by type I interferons in response to inflammatory signals. Instead of the well-established role for liver X receptors in stimulating cholesterol efflux, we demonstrate that liver X receptors are necessary for the proper resumption of cholesterol synthesis in response to inflammatory signals. Thus, liver X receptors function as bidirectional regulators of cholesterol homeostasis, driving efflux when cholesterol levels are high and facilitating synthesis in response to inflammatory signals. Liver X receptor activity is also required for the proper shutdown of a subset of type I interferon-stimulated genes as inflammation subsides, placing the receptors in a negative-feedback loop that may contribute to the resolution of the inflammatory response.

Tobacco smoking induces changes in true DNA methylation, hydroxymethylation and gene expression in bronchoalveolar lavage cells

Background

While smoking is known to associate with development of multiple diseases, the underlying mechanisms are still poorly understood. Tobacco smoking can modify the chemical integrity of DNA leading to changes in transcriptional activity, partly through an altered epigenetic state. We aimed to investigate the impact of smoking on lung cells collected from bronchoalveolar lavage (BAL).

Methods

We profiled changes in DNA methylation (5mC) and its oxidised form hydroxymethylation (5hmC) using conventional bisulphite (BS) treatment and oxidative bisulphite treatment with Illumina Infinium MethylationEPIC BeadChip, and examined gene expression by RNA-seq in healthy smokers.

Findings

We identified 1667 total 5mC + 5hmC, 1756 5mC and 67 5hmC differentially methylated positions (DMPs) between smokers and non-smokers (FDR-adjusted P <.05, absolute Δβ >0.15). Both 5mC DMPs and to a lesser extent 5mC + 5hmC were predominantly hypomethylated. In contrast, almost all 5hmC DMPs were hypermethylated, supporting the hypothesis that smoking-associated oxidative stress can lead to DNA demethylation, via the established sequential oxidation of which 5hmC is the first step. While we confirmed differential methylation of previously reported smoking-associated 5mC + 5hmC CpGs using former generations of BeadChips in alveolar macrophages, the large majority of identified DMPs, 5mC + 5hmC (1639/1667), 5mC (1738/1756), and 5hmC (67/67), have not been previously reported. Most of these novel smoking-associating sites are specific to the EPIC BeadChip and, interestingly, many of them are associated to FANTOM5 enhancers. Transcriptional changes affecting 633 transcripts were consistent with DNA methylation profiles and converged to alteration of genes involved in migration, signalling and inflammatory response of immune cells.

Interpretation

Collectively, these findings suggest that tobacco smoke exposure epigenetically modifies BAL cells, possibly involving a continuous active demethylation and subsequent increased activity of inflammatory processes in the lungs.

Fund

The study was supported by the Swedish Research Council, the Swedish Heart-Lung Foundation, the Stockholm County Council (ALF), the King Gustav's and Queen Victoria's Freemasons' Foundation, Knut and Alice Wallenberg Foundation, Neuro Sweden, and the Swedish MS foundation.

LncRNA ENST00000602558.1 regulates ABCG1 expression and cholesterol efflux from vascular smooth muscle cells through a p65-dependent pathway

BACKGROUND AND AIMS

Long non-coding RNAs (lncRNAs) have proven to be involved in the progression of atherosclerosis and dyslipidemia. In addition, vascular smooth muscle cells (VSMCs) phenotype switching, including VSMCs-derived foam cells formation, plays a key role in the pathogenesis of atherosclerosis. LncRNA ENST00000602558.1, one of the differentially expressed lncRNAs between coronary artery disease (CAD) patients and healthy controls identified by our previous study, was located to TG and HDL susceptibility loci, but its role and underlying mechanism in the pathogenesis of atherosclerosis remain unclear. The present study aims to explore the role and underlying mechanism of ENST00000602558.1 in the regulation of cholesterol efflux from VSMCs.

METHODS

ABCG1 mRNA and protein expression in VSMCs was detected using qRT-PCR and Western blot, respectively. ABCG1-mediated cholesterol efflux to HDL from VSMCs was measured by means of NBD-cholesterol fluorescence intensity. The binding of ENST00000602558.1 to p65 and p65 to ABCG1 promoter region was detected by RNA immunoprecipitation (RIP) assay and chromatin immunoprecipitation (ChIP) assay, respectively.

RESULTS

Overexpression of ENST00000602558.1 downregulated ABCG1 mRNA and protein expression, while knockdown of ENST00000602558.1 upregulated ABCG1 mRNA and protein expression. Consistently, ENST00000602558.1 overexpression decreased ABCG1-mediated cholesterol efflux to HDL from VSMCs by 30.38% (p < 0.001), and knockdown of ENST00000602558.1 increased ABCG1-mediated cholesterol efflux to HDL from VSMCs by 30.41% (p = 0.001). In addition to cholesterol efflux, overexpression of ENST00000602558.1 increased lipid accumulation and TC/TG levels, while knockdown of ENST00000602558.1 decreased lipid accumulation and TC/TG levels in VSMCs. Furthermore, we confirmed that ENST00000602558.1 regulated ABCG1 expression and ABCG1-mediated cholesterol efflux from VSMCs through binding to p65.

CONCLUSIONS

In conclusion, ENST00000602558.1 played an important role in mediating cholesterol efflux to HDL from VSMCs by regulating ABCG1 expression through binding to p65.

Transcriptional profiling of human microglia reveals grey-white matter heterogeneity and multiple sclerosis-associated changes

Here we report the transcriptional profile of human microglia, isolated from normal-appearing grey matter (GM) and white matter (WM) of multiple sclerosis (MS) and non-neurological control donors, to find possible early changes related to MS pathology. Microglia show a clear region-specific profile, indicated by higher expression of type-I interferon genes in GM and higher expression of NF-κB pathway genes in WM. Transcriptional changes in MS microglia also differ between GM and WM. MS WM microglia show increased lipid metabolism gene expression, which relates to MS pathology since active MS lesion-derived microglial nuclei show similar altered gene expression. Microglia from MS GM show increased expression of genes associated with glycolysis and iron homeostasis, possibly reflecting microglia reacting to iron depositions. Except for ADGRG1/GPR56, expression of homeostatic genes, such as P2RY12 and TMEM119, is unaltered in normal-appearing MS tissue, demonstrating overall preservation of microglia homeostatic functions in the initiation phase of MS.

Hyperlipidemias and Obesity

The organs require oxygen and other types of nutrients (amino acids, sugars, and lipids) to function, the heart consuming large amounts of fatty acids for oxidation and adenosine triphosphate (ATP) generation.

Relationship between ABCA1 gene polymorphism and lacunar infarction combined with arteriosclerosis in patients

Adenosine triphosphate-binding cassette transporter A1 (ABCA1) gene polymorphism in lacunar infarction (LI) combined with arteriosclerosis was investigated. A total of 112 LI patients complicated with arteriosclerosis treated in Ningbo First Hospital from March 2015 to September 2016 were enrolled as observation group. At the same time, 342 healthy subjects were selected from physical examination center to serve as the control group. The ABCA1 gene polymorphism was detected via polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and the susceptibility of ABCA1 gene to LI complicated with atherosclerosis was studied. There were no significant differences in serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and lipoprotein (a) [Lp(a)] between the two groups (P>0.05). Levels of triglyceride (TG) and apolipoprotein B (ApoB) in observation group were significantly higher than those in control group, but levels of ApoA-I and high-density lipoprotein cholesterol (HDL-C) were significantly lower in observation group than those in control group (P<0.05). There were no significant differences in the RR, RK and KK frequencies and allele frequency of ABCA1 R219K genotype between the two groups (P>0.05). Moreover, levels of HDL-C increased in the RR, RK and KK genotypes, but were not statistically significant (P>0.05). Levels of TG, TC, LDL-C, ApoA-I, ApoB and Lp(a) showed no significant differences among different genotypes of ABCA1 R219K (P>0.05). Results indicated that ABCA1 R219K polymorphism has no correlation with LI complicated with arteriosclerosis.

Identification of the ER-resident E3 ubiquitin ligase RNF145 as a novel LXR-regulated gene

Cellular cholesterol metabolism is subject to tight regulation to maintain adequate levels of this central lipid molecule. Herein, the sterol-responsive Liver X Receptors (LXRs) play an important role owing to their ability to reduce cellular cholesterol load. In this context, identifying the full set of LXR-regulated genes will contribute to our understanding of their role in cholesterol metabolism. Using global transcriptional analysis we report here the identification of RNF145 as an LXR-regulated target gene. We demonstrate that RNF145 is regulated by LXRs in both human and mouse primary cells and cell lines, and in vivo in mice. Regulation of RNF145 by LXR depends on a functional LXR-element in its proximal promotor. Consistent with LXR-dependent regulation of Rnf145 we show that regulation is lost in macrophages and fibroblasts from Lxrαβ(-/-) mice, and also in vivo in livers of Lxrα(-/-) mice treated with the LXR synthetic ligand T0901317. RNF145 is closely related to RNF139/TRC8, an E3 ligase implicated in control of SREBP processing. However, silencing of RNF145 in HepG2 or HeLa cells does not impair SREBP1/2 processing and sterol-responsive gene expression in these cells. Similar to TRC8, we demonstrate that RNF145 is localized to the ER and that it possesses intrinsic E3 ubiquitin ligase activity. In summary, we report the identification of RNF145 as an ER-resident E3 ubiquitin ligase that is transcriptionally controlled by LXR.