apoA-I Gene Research Articles

RVX-208, an inducer of Apolipoprotein A-I, inhibits the particle production of hepatitis B virus through activation of cGAS-STING pathway.

Previously, we have demonstrated that Apolipoprotein A-I (ApoA-I) could inhibit the secretion of Hepatitis B virus (HBV), suggesting that stimulation of ApoA-I may block particle production. In the present study, we evaluated the anti-HBV effect of RVX-208, a small-molecule stimulator of ApoA-I gene expression. RVX-208 was used to treat HepG2.2.15 cell, a HepG2 derived cell line stably producing HBV virus. Real-time PCR was performed to examine the HBV DNA levels. Magnetic particles, which were coated with anti-HBS or anti-HBE antibody, were used to examine the HBsAg and HBeAg levels in the supernatant of cultured HepG2.2.15 cells in combination with the enzyme conjugates that were prepared with horseradish peroxidase labelled anti-HBS or anti-HBE antibody in a double antibody sandwich manner. RNA-seq, immunoblots and real-time PCR were used to analyze the functional mechanism of RVX-208. RVX-208 could elevate the ApoA-I protein levels in HepG2.2.15 cells. In the meantime, RVX-208 significantly repressed HBV DNA, HBsAg and HBeAg levels in the supernatants of HepG2.2.15 cells. RNA-seq data revealed that RVX-208 treatment not only affected the cholesterol metabolism, which is closely related to ApoA-I, but also regulated signalling pathways that are associated with antiviral immune response. Moreover, mechanistic studies demonstrated that RVX-208 could activate cGAS-STING pathway and upregulate the transcription of a series of interferons, pro-inflammatory cytokines and chemokines with antiviral potential that are at the downstream of cGAS-STING pathway. Our study demonstrated that RVX-208, an inducer of ApoA-I, could suppress HBV particle production through activation of cGAS-STING pathway.

Expression of concern to 'Depletion of TDP 43 overrides the need for exonic and intronic splicing enhancers in the human apoA-II gene'.

Expression of concern to 'Depletion of TDP 43 overrides the need for exonic and intronic splicing enhancers in the human apoA-II gene'.

Abstract TP226: Impact Of Apolipoprotein A-i In The Attenuation Of Stroke And Stroke Symptoms

Apolipoprotein AI is the major protein component of high-density lipoprotein (HDL) particles in plasma. Inflammatory cytokines such as TNF and IL-1β repress the production of ApoA-I from hepatocytes and increase the expression of serum amyloid A (SAA), which becomes the major protein component of HDL in this context. Consequently, lipid-poor ApoA-I is rapidly catabolized in the liver and the kidney. These findings could be meaningful if ApoA-I, in addition to its proimmune features, had anti-inflammatory potential. In this way, removal of ApoA-I could intensify the inflammatory response, resulting in a more robust effect. Recent studies have suggested that serum apolipoprotein A1 maybe a predictor and prognostic biomarker in acute ischemic stroke in humans. To understand the impact of ApoA-I in stroke, we have begun to analyze the role of ApoA-I in mouse models of stroke. Mice with reduced or deficient in ApoA-I and subjected to ischemia and reperfusion injury or permanent ischemia, had increased inflammatory responses, larger infarct volumes, and poorer outcomes than wildtype mice. Mice transgenic for the human ApoA-I gene showed a level of protection not seen in the wildtype mice when given an ischemic injury. Administration of AAV human ApoA-I increased HDL levels in deficient mice and provided protection against ischemic injury. Additionally, drugs to enhance ApoA-I expression showed protection against strokes in the mouse models. These studies, along with subsequent investigations will provide a better understanding and potential therapeutic approaches in the field of stroke.

Novel expression cassettes for increasing apolipoprotein AI transgene expression in vascular endothelial cells

Transduction of endothelial cells (EC) with a vector that expresses apolipoprotein A-I (APOAI) reduces atherosclerosis in arteries of fat-fed rabbits. However, the effects on atherosclerosis are partial and might be enhanced if APOAI expression could be increased. With a goal of developing an expression cassette that generates higher levels of APOAI mRNA in EC, we tested 4 strategies, largely in vitro: addition of 2 types of enhancers, addition of computationally identified EC-specific cis-regulatory modules (CRM), and insertion of the rabbit APOAI gene at the transcription start site (TSS) of sequences cloned from genes that are highly expressed in cultured EC. Addition of a shear stress-responsive enhancer did not increase APOAI expression. Addition of 2 copies of a Mef2c enhancer increased APOAI expression from a moderately active promoter/enhancer but decreased APOAI expression from a highly active promoter/enhancer. Of the 11 CRMs, 3 increased APOAI expression from a moderately active promoter (2–7-fold; P < 0.05); none increased expression from a highly active promoter/enhancer. Insertion of the APOAI gene into the TSS of highly expressed EC genes did not increase expression above levels obtained with a moderately active promoter/enhancer. New strategies are needed to further increase APOAI transgene expression in EC.

Importance of Polymorphisms in the Gene of Paraoxonase-1 (SNP rs662) and Apolipoprotein A-I (SNP rs670 and rs5069) in Non-Smoking and Smoking Healthy Subjects and Patients with Acute Pancreatitis

Oxidative stress has been implicated in the initiation of acute pancreatitis (AP). HDL is considered to be a preventing factor against cell membrane oxidation, thanks to the presence on its surface of apolipoprotein A-I (apoA-I) and paraoxonase-1 (PON1), which activity can be modified by genetic and environmental factors. The impact of SNP rs662 in the PON1 gene and SNP rs670 and rs5069 in the APOAI gene on PON1 activities and its concentration in the population of AP patients and healthy volunteers was investigated. In the group of patients with AP, a decreased HDL concentration and PON1 activities were observed. A decrease in the aryloesterase and lactonase activities of PON1 in AP patients with the TT genotype for SNP rs662 (especially in smokers) was found. In the group of patients with the AA genotype (rs670), the highest concentrations of HDL and apoA-I were observed, which were gradually decreasing in the course of AP. Changes in the concentration of apoA-I were associated with the changes in the concentration and activities of PON1 in the AP patients with the AA genotype for SNP rs670. A decreasing apoA-I concentration contributing to lowering PON1 concentration and its activities during the hospitalization of AP patients with the CC genotype for SNP rs5069 were shown. Therefore, more susceptibility of persons with the CC genotype for SNP rs5069 to pro/antioxidative imbalance was shown. In this process, an important role was played by the HDL level and its interaction with PON1 and apoA-I.

ERα promotes transcription of tumor suppressor gene ApoA-I by establishing H3K27ac-enriched chromatin microenvironment in breast cancer cells.

Apolipoprotein A-I (ApoA-I), the main protein component of high-density lipoprotein (HDL), plays a pivotal role in reverse cholesterol transport (RCT). Previous studies indicated a reduction of serum ApoA-I levels in various types of cancer, suggesting ApoA-I as a potential cancer biomarker. Herein, ectopically overexpressed ApoA-I in MDA-MB-231 breast cancer cells was observed to have antitumor effects, inhibiting cell proliferation and migration. Subsequent studies on the mechanism of expression regulation revealed that estradiol (E2)/estrogen receptor α (ERα) signaling activates ApoA-I gene transcription in breast cancer cells. Mechanistically, our ChIP-seq data showed that ERα directly binds to the estrogen response element (ERE) site within the ApoA-I gene and establishes an acetylation of histone 3 lysine 27 (H3K27ac)‍-enriched chromatin microenvironment. Conversely, Fulvestrant (ICI 182780) treatment blocked ERα binding to ERE within the ApoA-I gene and downregulated the H3K27ac level on the ApoA-I gene. Treatment with p300 inhibitor also significantly decreased the ApoA-I messenger RNA (mRNA) level in MCF7 cells. Furthermore, the analysis of data from The Cancer Genome Atlas (TCGA) revealed a positive correlation between ERα and ApoA-I expression in breast cancer tissues. Taken together, our study not only revealed the antitumor potential of ApoA-I at the cellular level, but also found that ERα promotes the transcription of ApoA-I gene through direct genomic effects, and p300 may act as a co-activator of ERα in this process.

Serum apolipoprotein A-I potentiates the therapeutic efficacy of lysocin E against Staphylococcus aureus

Lysocin E is a lipopeptide with antibiotic activity against methicillin-resistant Staphylococcus aureus. For unclear reasons, the antibacterial activity of lysocin E in a mouse systemic infection model is higher than expected from in vitro results, and the in vitro activity is enhanced by addition of bovine serum. Here, we confirm that serum from various species, including humans, increases lysocin E antimicrobial activity, and identify apolipoprotein A-I (ApoA-I) as an enhancing factor. ApoA-I increases the antibacterial activity of lysocin E when added in vitro, and the antibiotic displays reduced activity in ApoA-I gene knockout mice. Binding of ApoA-I to lysocin E is enhanced by lipid II, a cell-wall synthesis precursor found in the bacterial membrane. Thus, the antimicrobial activity of lysocin E is potentiated through interactions with host serum proteins and microbial components.

Differential Expression of the Apolipoprotein AI Gene in Spotnape Ponyfish (Nuchequula nuchalis) Inhabiting Different Salinity Ranges at the Top of the Estuary and in the Deep-Bay Area of Gwangyang Bay, South Korea.

Spotnape ponyfish (Nuchequula nuchalis) is a dominant species that is broadly distributed from estuarine to deep-bay areas, reflecting a euryhaline habitat. Apolipoprotein AI (ApoAI) is a main component of plasma lipoproteins and has crucial roles in lipid metabolism and the defense immune system. In this study, we characterized the N. nuchalis ApoAI gene and analyzed the expression of the ApoAI transcript in N. nuchalis collected at various sites in the estuary and the deep-bay area which have different salinities. Owing to the fish’s mobility, we conducted stable isotope analyses to confirm the habitat characteristics of N. nuchalis. Carbon and nitrogen isotope ratios (δ13C and δ15N) from N. nuchalis indicated different feeding sources and trophic levels in the estuarine and deep-bay habitats. The characterized N. nuchalis ApoAI displayed residual repeats that formed a pair of alpha helices, indicating that the protein belongs to the apolipoprotein family. In the phylogenetic analysis, there was no sister group of N. nuchalis ApoAI among the large clades of fish species. The transcriptional expression level of ApoAI was higher in N. nuchalis inhabiting the deep-bay area with a high salinity (over 31 psu) than in N. nuchalis inhabiting the top of the estuary with a low salinity (6~15 psu). In addition, the expression patterns of N. nuchalis ApoAI were positively correlated with environmental factors (transparency, pH, TC, and TIC) in the high salinity area. These results suggest that ApoAI gene expression can reflect habitat characteristics of N. nuchalis which traverse broad salinity ranges and is associated with functional roles of osmoregulation and lipid metabolism for fish growth and development.

The Promise of Apolipoprotein AI-Based Therapy

Apolipoprotein A-I (ApoAI) is an anti-atherosclerotic protein that promotes cholesterol efflux from tissues to the liver for excretion [1]. ApoAI is the main structural and functional protein of High- Density Lipoproteins (HDL), representing ~70% of total HDL proteins [2,3]. Circulating apoAI protein is an amphipathic protein (28kDa) comprising eight alpha-helical domains of 22 amino acids and two repeats of 11 amino acids [4]. Consequently, ApoAI binds avidly to lipids and readily moves between lipoprotein particles; however, ~5-10% of human plasma ApoAI exists in a free state (lipoprotein-unbound) [5]. ApoAI protein is more than a structural scaffold that maintains lipid packaging, as it plays an important role in the transport of cellular cholesterol from the artery wall to the liver for catabolism [6-8]. Antioxidant and anti-inflammatory properties were also attributed to apoAI [9,10]. In addition, a protective role of apoAI against cancer was proposed [11]. ApoAI is synthesized mainly in the liver and small intestine and there are a lot of regulatory elements and transcription factors that control apoAI gene expression, as reviewed in [12]. Treatment with BPA (bisphenol A), one of the most widespread environmental chemicals, downregulates ApoAI gene expression, aggravating the atherosclerotic plaques in LDLR-/- mice [13]. Interestingly, the ratio of HDL-cholesterol to apoAI protein levels is an indicator of the risk of the cardiovascular disorder [14]. Lack of ApoAI augmented atherosclerosis in various hypercholesterolemic mice, such as mice expressing human apoB or ApoAI-/-/LDLR-/- mice [15,16]. In humans, familial ApoAI deficiency is associated with premature coronary heart disease [17]. Interestingly, low levels of apoAI and atherogenic dyslipidemia were found in obese individuals, but increases in apoAI levels and enhancements of cholesterol efflux capacity of HDL were reported at three months after bariatric surgery [18]. Considering the anti-atherogenic properties of apoAI, various apoAI-based therapies were proposed for reduction of atherogenesis: i) overexpression of ApoAI, ii) infusions of ApoAI protein, ApoAI mimetic peptides, or ApoAI-containing HDL [19-21], iii) oral small molecules that stimulate ApoAI production [22]. Overexpression of ApoAI reduced atherogenesis in apoE-/- or LDLR-/- atherosclerotic mice [23-31]. Infusions of ApoAI mimetic peptides led to the regression of aortic valve stenosis in rabbits [32]. Liver-directed adenoviral gene transfer of ApoAI resulted in the regression of preexisting atheroma in LDLR-/- mice [33]. Undoubtedly, local delivery of apoAI protein to the vascular wall represents a more efficient apoAIbased therapy than its systemic delivery. Remarkably, transduction of vascular endothelial cells with ApoAI expressing adenovirus reduced inflammation and protected against atherosclerosis in hyperlipidemic rabbits [34,35]. The oral drug RVX-208 significantly increased apoAI production in monkeys but presented disappointing efficacy in a phase II trial [36]. Notwithstanding there are good results obtained in studies using animal models, several apoAI-based clinical trials failed to regress atherosclerotic plaques in humans [37,38]. Despite tremendous advances regarding the understanding of apoAI, the promise of apoAI-based therapy awaits new studies and trials.

Effect of eight weeks of regular aerobic exercise on apolipoprotein AI gene expression and lipid profile indices in obese women

Background: Heart disease is a multifactorial disease with genetic background and environmental factors involved. And new studies believe that markers such as apolipoprotein AI are a better criterion for diagnosis. Therefore, the purpose of this study was to investigate the effect of eight weeks of regular aerobic exercise on apolipoprotein AI gene expression and lipid profile indices in obese women. Methods: In this experimental study, 30 healthy obese women aged 35-30 years were randomly selected and divided into control (n =15) and experimental (n =15) groups. The experimental group underwent 8 weeks of regular aerobic exercise at 60-75% of the heart rate reserve three sessions per week for 60 minutes each session. Apolipoprotein AI mRNA expression was measured by Semi-quantitative-RT-PCR method and lipid profiles were measured in both pre-test and post-test. Results: The apolipoprotein AI gene expression was significantly increased in the experimental group compared to the control group (P&lt;0.05). Also, TG (P = 0.003), TG LDL in the experimental group showed a significant decrease compared to the control group and HDL level in the experimental group was significantly higher than the control group (P = 0.001) Conclusion: The regular aerobic exercise has an important role in reducing cardiovascular diseases through increasing apolipoprotein AI gene expression and improving lipid

Basolateral Secretion from Caco-2 Cells Pretreated with Fecal Waters from Breast Cancer Patients Affects MCF7 Cell Viability.

We hypothesized that the role of microbiota in breast cancer relates to its influence on gut lipid metabolism. This was tested in an in vitro model combining MCF-7 and Caco-2 cells. A total of 32 women newly diagnosed for breast cancer before any treatment and 28 healthy women provided their stools. Bacterial DNA was amplified by qPCR targeting 16s rRNA specific to Bacteroidetes and Firmicutes phyla, Lactobacillales sp., Clostridium cluster IV, Faecalibacterium prausnitzii, Clostridium cluster XIVa, Roseburia intestinalis, Blautia sp., Lactonifactor longoviformis, Bifidobacterium sp., Coriobacteriaceae, Eggertella lenta, Escherichia, and Shigella. Fecal waters (FW) were quantified for short chain fatty acids (SCFA). Caco-2 cells grown on filter inserts were incubated apically with 10% FW for 24 h, and LXR, apolipoproteins AIV, and E gene expression were estimated by real time (RT) qPCR. Then, MCF-7 cells were incubated with the whole basolateral medium for 24 h, and their viability was estimated by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) test. Regression models were used to determine the correlation between MCF-7 viability and bacteria relative abundance, Caco-2 cells lipid metabolism gene expression and stool composition, as well as microbiota composition and short chain fatty acids. Logistic regression models established disease odds ratios (OR) for MCF-7 viability and Caco-2 gene expression. The OR of MCF-7 viability was 1.05 (1.01–1.10) (OR (5th–95th), p = 0.04), while that of apo AIV gene expression was 0.63 (0.39–1.01), p = 0.055). Viability correlated with % Bifidobacterium sp. (21.18 ± 7.66, p = 0.008) and valerate (−2.849 ± 1.048, p = 0.009) (β ± s.d.). This study suggests that microbiota interacts with intestine cell lipid metabolism. Since these metabolites can reach breast cells by systemic circulation, we hypothesized that they may influence cancer disease.

Naked Mole-Rat, a Rodent with an Apolipoprotein A-I Dimer.

A variety of rodents have been used as experimental animals in metabolic studies of plasma lipids and lipoproteins. These studies have included understanding the functional role of apolipoprotein A-I, the major protein on the surface of HDL. Reviewing the genomic database for entries for rodent apoA-I genes, it was discovered that the naked mole-rat (Heterocephalus glaber) gene encoded a protein with a cysteine at residue 28. Previously, two cases have been reported in which human heterozygotes had apoA-I with cysteine at residues 173 (apoA-I Milano) or at 151 (apoA-I Paris). Interestingly, both groups, in spite of having low levels of HDL and moderately elevated plasma triacylglycerols, had no evidence of cardiovascular disease. Moreover, the presence of the cysteine enabled the apoA-I to form both homodimers and heterodimers. Prior to this report, no other mammalian apoA-I has been found with a cysteine in its sequence. In addition, the encoded naked mole-rat protein had different amino acids at sites that were conserved in all other mammals. These differences resulted in naked mole-rat apoA-I having an unexpected neutral pI value, whereas other mammalian apoA-I have negative pI values. To verify these sequence differences and to determine if the N-terminal location of C28 precluded dimer formation, we conducted mass spectrometry analyses of apoA-I and other proteins associated with HDL. Consistent with the genomic data, our analyses confirmed the presence of C28 and the formation of a homodimer. Analysis of plasma lipids surprisingly revealed a profile similar to the human heterozygotes.

The effects of combined exercise program on several clinical parameters according to a MspI RFLP in ApoAII gene in obese middle-aged women

The effects of combined exercise program on several clinical parameters according to a MspI RFLP in ApoAII gene in obese middle-aged women

Effect of the insulin on the apolipoprotein a-i gene expression in human macrophages

The aim of the article to study the effect of insulin on apolipoprotein A-I gene expression level in human macrophages and to reveal the main signal cascades which take part in the insulin-mediated regulation of apolipoprotein A-I gene.&#x0D; Materials and methods. The experiments were carried out on the macrophages differentiated from acute monocytic leukemia cell line THP-1 and on the macrophages differentiated from the monocytes isolated from peripheral human blood. The analysis of apoA-I gene expression was performed by RealTime RT-PCR (on the mRNA level) and by flow cytofluorometry. To study the signalling cascades which take part in the insulin-mediated regulation of apoA-I gene the inhibitory analysis was used.&#x0D; Results. Insulin induces the human apoA-I gene transcription in macrophages, but decreases the level of the ApoA-I protein which binds to outer cytoplasmic membrane of macrophages. The insulin-mediated transcription of apoA-I gene depends on PI3K-AKT signal cascade and transcription factors NF-B and LXRs.&#x0D; Conclusions. Taking into account our previous data it is plausible to conclude that the elevation of ApoA-I mRNA in human macrophages after insulin treatment leads to an increase of the amplitude of macrophages anti-inflammatory response, which consists in a sharp rise in the level of surface ApoA-I in macrophages under the some proinflammatory stimuli (TNF, LPS).

Viability of MCF7 Cells Exposed to Basolateral Secretion from CaCo2 Cells Pretreated with Fecal Waters from Breast Cancer Patients and Controls

Abstract Objectives There is increasing evidence suggesting that microbiota may play a role in breast cancer disease and influence the disease severity. Several mechanisms may be involved in this relationship. Our hypothesis is that the role of microbiota in the disease may be at least partly related to its influence in gut lipid and lipoprotein metabolisms. This hypothesis was tested in an in vitro model combining MCF7 and Caco2 cells. Methods 32 women newly diagnosed for breast cancer, before any treatment and 28 apparently healthy women provided their stools from which bacterial DNA was extracted and amplified by qPCR, targeting 16S rRNA sequences specific to bacterial groups. Fecal waters (FW) were also obtained from these stools. Intestinal Caco-2 cells grown on filter inserts were incubated apically with 10% FW for 24 h. Then, MCF-7 cells were incubated with the whole basolateral medium for 24 h. The viability of these cells was estimated by MTT test. In parallel, LXR, apolipoproteins AIV and E gene expression was estimated by RT QPCR in CaCo2 cells and short chain fatty acids (SCFA) were quantified in FW. A logistic regression model was used to establish the Odds ratios (OR) for the disease of MCF7 viability and CaCo2 gene expression. The relationship between % bacterial groups, CaCo2 gene expression, SCFA and viability was established by regression models. Results Patients and controls differed by the MCF7 viability (1.05 [1.01–1.10], p = 0.04) and a tendency towards a difference was observed for apo AIV gene expression (0.63 [0.39–1.01], p = 0.055), (OR [5th-95th]). Viability was positively correlated with % Bifidobacterium sp. (21.18 ± 7.66, p = 0.008) and negatively correlated with valerate (−2.849 ± 1.048, p = 0.009), (ß±s.d.). These correlations were maintained in a multiple regression model. Conclusions Microbiota may interact with intestine cell lipid metabolism and therefore influence cancer disease through gut cell secretion or permeability. Funding Sources Ligue Contre le cancer and private funds from Integrated Center for Oncology.

Identification, expression analysis, and antibacterial activity of Apolipoprotein A-I from amphioxus (Branchiostoma belcheri).

Apolipoprotein A-I (ApoA-I) plays an important role in lipid transport and performs an antimicrobial activity in vertebrates. However, the role of ApoA-I in invertebrates remains largely unexplored. In this study, an ApoA-I gene named BbApoA-I having an open reading frame of 1466 bp and encoding a polypeptide of 345 amino acids was cloned from a cephalochordate (Branchiostoma belcheri). The predicted polypeptide revealed conserved features, including α-helical secondary structures and coiled-coil regions in known vertebrate ApoA-I sequences. Quantitative real-time PCR analysis indicated that BbApoA-I was detected in all of the tested tissues, and the highest expression was found in the hepatic cecum. The BbApoA-I expression was upregulated after the specimens were injected with lipopolysaccharide. Recombinant BbApoA-I produced in an E. coli expression system was able to bind to a wide range of Gram-positive and Gram-negative bacteria as well as lipopolysaccharide and lipoteichoic acid. In addition, rBbApoA-I exhibited in vitro antibacterial activity against Gram-negative bacteria. These results indicated that BbApoA-I performed a protective function against bacterial infection in amphioxus.

The Endogenous Apolipoprotein A-I Enhances The Uptake Of Oxidated Low Density Lipoprotein By Macrophages

Background and Aims: Apolipoprotein A-I (ApoA-I) is the main structural and functional protein component of high-density lipoprotein. Recently we found the moderate expression of endogenous apoA-I in human monocytes and macrophages and showed the anti-inflammatory influence of endogenous ApoA-I on macrophages. The homogeneous population of monocytes divides to the ApoA-I-rich and ApoA-I-poor macrophages during the differentiation. The functions of macrophagal ApoA-I in the development of atherosclerotic lesions are still unknown. Here we show the participation of macrophagal ApoA-I in the uptake of oxidated Low Density Lipoprotein (oxLDL) and study the apoA-I gene regulation in macrophages by oxLDL.

Enhanced cellular cholesterol efflux by naringenin is mediated through inhibiting endoplasmic reticulum stress - ATF6 activity in macrophages

Naringenin improves lipoprotein profile and protects against cardiovascular disease. ATF6 is an endoplasmic reticulum (ER) stress sensor with the same activation processes with sterol regulator SREBPs. Clinical data revealed that ATF6 expression was associated with plasma cholesterol level. Here, we investigated whether naringenin was involved in the regulation of cholesterol efflux and tested the role of ER stress-ATF6 in the naringenin function. Results showed that naringenin increased cholesterol efflux to both apoA-I and HDL and gene expressions in ABCA1, ABCG1 and LXRα in RAW264.7 macrophages. Naringenin inhibited the cleaved ATF6 nuclear translocation and its target GRP78 and XBP-1 expressions. Naringenin-induced cholesterol efflux was modulated by treatment with ER stress inhibitor 4-phenylbutyric acid, inducer tunicamycin and ATF6 overexpression in RAW264.7 and/or THP-1 cells, which suggested the naringenin functions were mediated through inhibiting ER stress-ATF6 pathway. Next, we found high-fat diet (HFD) supplemented with naringenin increased by >1.2-fold in cholesterol efflux capacity in primary peritoneal macrophage in apoE−/− mice compared to only HFD-fed mice. The increase was significantly reduced by tunicamycin treatment. Naringenin decreased GRP78, XBP-1 and nuclear ATF6 levels in peritoneal macrophage and aorta and reduced atherosclerotic lesion at aortic root, but reversed by tunicamycin. These confirmed participation of ER stress-ATF6 in naringenin efficacy. Finally, we found naringenin promoted AKT phosphorylation; PI3K inhibitor LY294002 treatment increased nuclear ATF6 and reduced naringenin-enhanced ABCA1 expression and cholesterol efflux. We concluded naringenin as a regulator for cholesterol efflux, and the regulation was mediated by ATF6 branch of ER stress and PI3K/AKT pathway.

HDL Dysfunction Caused by Mutations in apoA-I and Other Genes that are Critical for HDL Biogenesis and Remodeling.

The "HDL hypothesis" which suggested that an elevation in HDL cholesterol (HDL-C) levels by drugs or by life style changes should be paralleled by a decrease in the risk for Cardiovascular Disease (CVD) has been challenged by recent epidemiological and clinical studies using HDL-raising drugs. HDL components such as proteins, lipids or small RNA molecules, but not cholesterol itself, possess various atheroprotective functions in different cell types and accumulating evidence supports the new hypothesis that HDL functionality is more important than HDL-C levels for CVD risk prediction. Thus, the detailed characterization of changes in HDL composition and functions in various pathogenic conditions is critically important in order to identify new biomarkers for diagnosis, prognosis and therapy monitoring of CVD. Here we provide an overview of how HDL composition, size and functionality are affected in patients with monogenic disorders of HDL metabolism due to mutations in genes that participate in the biogenesis and the remodeling of HDL. We also review the findings from various mouse models with genetic disturbances in the HDL biogenesis pathway that have been generated for the validation of the data obtained in human patients and how these models could be utilized for the evaluation of novel therapeutic strategies such as the use of adenovirus-mediated gene transfer technology that aim to correct HDL abnormalities.

Characterization of Distal and Proximal Alternative Promoters of the Human ApoA-I Gene

Characterization of Distal and Proximal Alternative Promoters of the Human ApoA-I Gene