apoB mRNA Research Articles

MicroRNA-615-3p decreases apo B expression in human liver cells

Plasma lipids are mainly carried in apolipoprotein B (apoB) containing lipoproteins. High levels of these lipoproteins are associated with several metabolic diseases and lowering their plasma levels is associated with reduced incidence of atherosclerotic cardiovascular disease. MicroRNAs (miRs) are small non-coding RNAs that reduce the protein expression of their target mRNAs and are potential therapeutic agents. Here, we identified a novel miR-615-3p that interacts with human 3′-UTR of apoB mRNA, induces post-transcriptional mRNA degradation, and reduces cellular and secreted apoB100 in human hepatoma Huh-7 cells. Reducing cellular miR-615-3p levels by CRISPR-sgRNA increased cellular and secreted apoB100 indicating endogenous miR regulates apoB expression. Overexpression of miR-615-3p along with or without palmitic acid treatment decreased cellular and media apoB and increased cellular triglyceride levels without inducing endoplasmic reticulum stress. These studies have identified miR-615-3p as a negative regulator of apoB expression in human liver-derived cells. It is likely that there are more miRs that regulate apoB-containing lipoprotein assembly and secretion. Discovery of additional miRs may uncover novel mechanisms that control lipoprotein assembly and secretion.

Abstract 3041: APOB Gene Deletion Increases The Expression Of Vitamin D Binding Protein In Human Hepatoma Cells

High plasma apolipoprotein B (apoB)-containing lipoproteins are both a biomarker and a causal mediator of many metabolic diseases. Inhibition of APOB mRNA decreases plasma lipid levels but at a risk of lipid accumulation in tissues. To understand the global consequences of reduced apoB synthesis, we generated a human hepatoma (Huh-7) cell culture model system deficient in apoB. ApoB deficient Huh-7 cells (Ako) were generated using the CRISPR/Cas9 system. Total RNA for transcriptomics and overnight conditioned media for proteomics and lipidomics was obtained from the Ako and Huh-7 cells (n=3). Statistical analysis was done using Student’s t-test while comparing two groups, p < 0.05 was considered significant. APOB gene deletion significantly reduced APOB mRNA and protein levels in the Ako cells compared to control cells. Ako cells supported apoB48 secretion when transfected with apoB48 expression plasmids. These cells did not accumulate significant amounts of triglyceride. KEGG pathway analysis of RNA-Seq data showed a significant increase in DNA replication/repair pathway and complement/coagulation cascade in the Ako cells. The most downregulated pathways included the PI3k-Akt signaling and MAPK signaling pathways. Differential gene expression analysis identified vitamin D binding protein (VDB, gene GC ) mRNA as the most highly upregulated transcript in Ako cells. The Ako media secretome contained significantly higher amounts of VDB compared to control Huh-7. Furthermore, targeted lipidomics of the secretome showed significant increases in media ergocalciferol. Our qPCR and western blot analysis confirmed increased expression of VDB mRNA and protein secretion in the Ako cells as compared to the Huh-7 cells. We established a cell culture model deficient in secreting apoB-containing lipoproteins. These cells, however, support the assembly and secretion of apoB48 when transfected with apoB48 expression plasmid. A major consequence of apoB deficiency was upregulation of the VDB expression. We interpret these data to suggest that human hepatoma cells have two differentially regulated pathways for the transport of vitamin D. In the absence of apoB-lipoprotein assembly, these cells upregulate VDB to augment secretion of vitamin D.

Abstract 1022: Microrna-615-3p Decreases Apolipoprotein B Expression In Human Liver Cells And Its Plasma Concentrations Are Inversely Correlated With Plasma Lipid Levels

Plasma lipids are mainly carried in apolipoprotein B (apoB) containing lipoproteins. High levels of these lipoproteins are associated with several metabolic diseases and lowering their plasma levels is associated with reduced incidence of atherosclerotic cardiovascular disease. MicroRNAs (miRs) are small non-coding RNAs that reduce protein expression of their target genes and are potential therapeutic agents. Here, we identified a novel miR-615-3p that interacts with human 3′-UTR of apoB mRNA, induces post-transcriptional mRNA degradation, and reduces cellular and secreted apoB100 in human hepatoma Huh-7 cells. Reducing cellular miR-615-3p levels by CRISPR-sgRNA increased cellular and secreted apoB100 indicating endogenous miR regulates apoB expression. Furthermore, we found that obese subjects have lower levels of miR-615-3p than healthy individuals. Moreover, there was a significant negative correlation between miR-615-3p and plasma lipids and apoB levels. These studies indicate that miR-615-3p negatively regulates apoB and its plasma levels could serve as a biomarker for obesity and possibly other metabolic diseases.

Contactin 5 and Apolipoproteins Interplay in Alzheimer's Disease.

Apolipoproteins and contactin 5 are proteins associated with Alzheimer's disease (AD) pathophysiology. Apolipoproteins act on transport and clearance of cholesterol and phospholipids during synaptic turnover and terminal proliferation. Contactin 5 is a neuronal membrane protein involved in key processes of neurodevelopment. To investigate the interactions between contactin 5 and apolipoproteins in AD, and the role of these proteins in response to neuronal damage. Apolipoproteins (measured by Luminex), contactin 5 (measured by Olink's proximity extension assay), and cholesterol (measured by liquid chromatography mass spectrometry) were assessed in the cerebrospinal fluid (CSF) and plasma of cognitively unimpaired participants (n = 93). Gene expression was measured using polymerase chain reaction in the frontal cortex of autopsied-confirmed AD (n = 57) and control subjects (n = 31) and in the hippocampi of mice following entorhinal cortex lesions. Contactin 5 positively correlated with apolipoproteins B (p = 5.4×10-8), D (p = 1.86×10-4), E (p = 2.92×10-9), J (p = 2.65×10-9), and with cholesterol (p = 0.0096) in the CSF, and with cholesterol (p = 0.02), HDL (p = 0.0143), and LDL (p = 0.0121) in the plasma. Negative correlations were seen between CNTN5, APOB (p = 0.034) and APOE (p = 0.015) mRNA levels in the brains of control subjects. In the mouse model, apoe and apoj gene expression increased during the reinnervation phase (p < 0.05), while apob (p = 0.023) and apod (p = 0.006) increased in the deafferentation stage. Extensive interactions were observed between contactin 5 and apolipoproteins and cholesterol, possibly due to neuronal damage. The alterations in gene expression of apolipoproteins suggest a role in axonal, terminal, and synaptic remodeling in response to entorhinal cortex damage.

APOBEC-1 Complementation Factor: From RNA Binding to Cancer.

APOBEC-1 complementation factor (A1CF) and Apolipoprotein B mRNA editing enzyme, catalytic polypeptide-1 (APOBEC-1) constitute the minimal proteins necessary for the editing of apolipoprotein B (apoB) mRNA in vitro. Unlike APOBEC-1 and apoB mRNA, the ubiquitous expression of A1CF in human tissues suggests its unique biological significance, with various factors such as protein kinase C, thyroid hormones, and insulin regulating the activity and expression of A1CF. Nevertheless, few studies have provided an overview of this topic. We conducted a literature review to describe the molecular mechanisms of A1CF and its relevance to human diseases. In the PubMed database, we used the keywords 'A1CF' and 'APOBEC-1 complementation factor' to collect peer-reviewed articles published in English from 2000 to 2023. Two authors independently reviewed the articles and reached the consensus. After reviewing 127 articles, a total of 61 articles that met the inclusion criteria were included in the present review. Studies revealed that A1CF is involved in epigenetic regulation of reproductive cells affecting embryonic development, and that it is closely associated with the occurrence of gout due to its editing properties on apoB. A1CF can also affect the process of epithelial-mesenchymal transition in renal tubular epithelial cells and promote liver regeneration by controlling the stability of IL-6 mRNA, but no influence on cardiac function was found. Furthermore, increasing evidence suggests that A1CF may promote the occurrence and development of breast cancer, lung cancer, renal cell carcinoma, hepatocellular carcinoma, endometrial cancer, and glioma. This review clarifies the association between A1CF and other complementary factors and their impact on the development of human diseases, aiming to provide guidance for further research on A1CF, which can help treat human diseases and promote health.

Hydrogen gas alleviates acute ethanol-induced hepatotoxicity in mice via modulating TLR4/9 innate immune signaling and pyroptosis

Alcoholic liver disease (ALD), which is induced by chronic heavy alcohol consumption, accompanies complicated pathological mechanisms, including oxidative stress, inflammation, cell death, epigenetic changes and acetaldehyde-mediated toxicity. Hydrogen (H2) is the lightest gas with multiple biological effects such as high selective anti-oxidation, anti-inflammation and anti-apoptosis. However, the dose effects and innate immune mechanisms of intraperitoneal injection of H2 on ALD are limited. Here, we used acute ethanol-induced hepatotoxicity mice models to estimate the actions of intraperitoneal injection of H2 on ALD. The effects of H2 on acute ethanol-induced liver damage were examined by hepatic oil red O staining, quantitative PCR (qPCR) for lipid metabolic genes, hepatic triglyceride (TG) and serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Hepatic mitochondrial superoxide (MitoSOX), 3-nitrotyrosine (3-NT), malondialdehyde (MDA), and glutathione (GSH) levels were examined to evaluate oxidative stress. Immunoblot, and immunofluorescence staining were used to further confirm the innate immune molecular targets of H2. Our results showed that intraperitoneal injection of H2 improved acute ethanol-induced liver injury in mice in a dose dependent manner, as indicated by decreasing serum ALT and AST levels, hepatic TG levels, and increasing lipid export genes (Mttp and Apob) mRNA levels and reducing fatty acid uptake gene (CD36) mRNA levels. Mechanistically, H2 inhibited hepatic oxidative stress as indicated by reducing reactive oxygen species (ROS), 3-NT, and MDA levels in the liver, while increasing hepatic GSH levels; inhibited the overactived TLR4/9-NF-κB-TNF-α/IL-1β/IL-18 innate immune signaling; suppressed the canonical Caspase-1-GSDMD pyroptosis signaling, and the non-canonical pyroptosis signaling, such as Caspase-11-GSDMD, Caspase-8-GSDMD and Caspase-3-GSDME signaling. Therefore, our study highlights that intraperitoneal injection of H2 may represent a novel therapeutic and safe strategy for ALD via modulating oxidative stress, innate immunity and pyroptosis.

Identification of RBM46 as A Novel APOBEC1 Cofactor for C-to-U RNA-Editing Activity

Cytidine (C) to Uridine (U) RNA editing is a post-transcription modification that is involved in diverse biological processes. APOBEC1 (A1) catalyzes the conversion of C-to-U in RNA, which is important in regulating cholesterol metabolism through its editing activity on ApoB mRNA. However, A1 requires a cofactor to form an “editosome“ for RNA editing activity. A1CF and RBM47, both RNA-binding proteins, have been identified as cofactors that pair with A1 to form editosomes and edit ApoB mRNA and other cellular RNAs. SYNCRIP is another RNA-binding protein that has been reported as a potential regulator of A1, although it is not directly involved in A1 RNA editing activity. Here, we describe the identification and characterization of a novel cofactor, RBM46 (RNA-Binding-Motif-protein-46), that can facilitate A1 to perform C-to-U editing on ApoB mRNA. Additionally, using the low-error circular RNA sequencing technique, we identified novel cellular RNA targets for the A1/RBM46 editosome. Our findings provide further insight into the complex regulatory network of RNA editing and the potential new function of A1 with its cofactors.

Bioresponsive Chimaeric Polymersomes Mediate Sustained and Liver-Specific siRNA Transfection In Vivo.

The silencing of disease-causing genes with small interfering RNA (siRNA) offers a particularly effective therapeutic strategy for different disorders; however, its clinical efficacy relies on the development of nontoxic and tissue-specific delivery vehicles. Herein, we report that bioresponsive chimaeric polymersomes (BCP) with short poly(ethylenimine) as inner shell mediate highly efficacious, sustained, and liver-specific siRNA transfection in vivo. BCP exhibited remarkable encapsulation efficiencies of siRNA (95-100%) at siRNA-feeding contents of 15-25 wt %, to afford stable, small-sized (55-64 nm), and neutral-charged BCP-siRNA. siApoB-Loaded BCP (BCP-siApoB) outperformed lipofectamine counterparts and silenced 93% of ApoB mRNA in HepG2 cells at 50 nM siApoB without inducing cytotoxicity. Intriguingly, the in vivo studies using wild-type C57BL/6 mice revealed that BCP-siApoB preferentially accumulated in the liver, and a single dose of 4.5 mg/kg achieved over 90% downregulation of ApoB mRNA for at least 10 days. The systemic administration of BCP-siApoB at 4.5 mg/kg every 2 weeks or 1.5 mg/kg weekly in diet-induced obese mice could also achieve up to 80% silencing of ApoB mRNA. The liver specificity and silencing efficacy of BCP-siApoB could further be improved by decorating it with the trivalent N-acetylgalactosamine (TriGalNAc) ligand. These bioresponsive and liver-specific chimaeric polymersomes provide an enabling technology for siRNA therapy of various liver-related diseases.

Exposure to acute waterborne cadmium caused severe damage on lipid metabolism of freshwater fish, revealed by nuclear lipid droplet deposition in hepatocytes of rare minnow

Cadmium (Cd) is a widely distributed aquatic toxic heavy metal with the potential to disrupt fish metabolism; however, more research is needed to clarify the underlying mechanisms. In the present study, rare minnows (Gobiocypris rarus) were used to detect the effects of cadmium on freshwater fish lipid metabolism and its underlying mechanism by histopathological observation, measurement of serum and liver biochemical indexes, and analysis of gene expression in terms of lipid oxidation, synthesis and transport. Here, severe damage, such as cytoplasmic lipid droplet (LD) accumulation, ectopic deposition of LDs, and the appearance of nuclear LDs (nLDs), was detected after exposure to 2.0 mg/L or higher concentrations (2.5 and 2.8 mg/L CdCl2) for 96 h. Other damage included abnormal increases in rough endoplasmic reticulum (RER) lamellae in a fingerprint or concentric circle pattern and necrosis of hepatocytes, and which was observed in the livers of fish exposed to 2.0 mg/L CdCl2.. Both hepatic and serum lipids, such as triglycerides and total cholesterol, were significantly increased after exposure to 2.0 mg/L CdCl2, as was serum lipase (LPS). Hepatic lipase and lipoprotein lipase remained unchanged, in accordance with the unchanged hepatic mRNA transcripts of PPARɑ. Furthermore, the mRNA transcripts of both SCD and SQLE were significantly decreased. Moreover, hepatic and serum low-density and high-density lipoprotein cholesterol showed significant changes, which were accompanied by a significant increase and decrease in hepatic APOAI and APOB100 mRNA levels, respectively. All the results indicate the presence of severe damage to hepatic lipid metabolism and that disrupted lipid transport may play a key role in the accumulation of hepatic LDs. In addition, the hepatic nLDs of nonmammalian vertebrates and their location across the nuclear envelope are intriguing, suggesting that large-size nLDs are a common marker for severe liver damage.

APOBEC mutagenesis is a common process in normal human small intestine

APOBEC mutational signatures SBS2 and SBS13 are common in many human cancer types. However, there is an incomplete understanding of its stimulus, when it occurs in the progression from normal to cancer cell and the APOBEC enzymes responsible. Here we whole-genome sequenced 342 microdissected normal epithelial crypts from the small intestines of 39 individuals and found that SBS2/SBS13 mutations were present in 17% of crypts, more frequent than most other normal tissues. Crypts with SBS2/SBS13 often had immediate crypt neighbors without SBS2/SBS13, suggesting that the underlying cause of SBS2/SBS13 is cell-intrinsic. APOBEC mutagenesis occurred in an episodic manner throughout the human lifespan, including in young children. APOBEC1 mRNA levels were very high in the small intestine epithelium, but low in the large intestine epithelium and other tissues. The results suggest that the high levels of SBS2/SBS13 in the small intestine are collateral damage from APOBEC1 fulfilling its physiological function of editing APOB mRNA.

Role of diacylglycerol O-acyltransferase (DGAT) isoforms in bovine hepatic fatty acid metabolism

Fatty acid accumulation in hepatocytes induced by high concentrations of fatty acids due to lipolysis and the associated oxidative damage they cause occur most frequently after calving. Because of their role in esterification of fatty acids, diacylglycerol acyltransferase isoforms (DGAT1 and DGAT2) could play a role in the susceptibility of dairy cows to develop fatty liver. To gain mechanistic insights, we performed in vivo and in vitro analyses using liver biopsies or isolated primary hepatocytes. The in vivo study (n = 5 cows/group) involved healthy cows [average liver triacylglycerol (TAG) = 0.78%; 0.58 to 0.93%, ratio of triglyceride weight to wet liver weight] or cows diagnosed with fatty liver (average TAG = 7.60%; 5.31 to 10.54%). In vitro, hepatocytes isolated from 3 healthy female calves (1 d old, 44 to 53 kg) were challenged with (fatty acids) or without (control) a 1.2 mM mixture of fatty acids in an attempt to induce metabolic stress. Furthermore, hepatocytes were treated with DGAT1 inhibitor or DGAT2 inhibitor for 2 h followed by a challenge with (DGAT1 inhibitor + fatty acids or DGAT2 inhibitor + fatty acids) or without (DGAT1 inhibitor or DGAT2 inhibitor) the 1.2 mM mixture of fatty acids for 12 h. Data analysis of liver biopsies was compared using a 2-tailed unpaired Student's t-test. Data from calf hepatocyte treatment comparisons were assessed by one-way ANOVA, and multiplicity for each experiment was adjusted by the Holm's procedure. Data indicated that both fatty liver and in vitro challenge with fatty acids were associated with greater mRNA and protein abundance of SREBF1, FASN, DGAT1, and DGAT2. In contrast, mRNA and protein abundance of CPT1A and very low-density lipoprotein synthesis-related proteins MTTP and APOB were markedly lower. However, compared with fatty acid challenge alone, DGAT1 inhibitor + fatty acids led to greater mRNA and protein abundance of CPT1A and APOB, and greater mRNA abundance of SREBF1 and MTTP. Furthermore, this treatment led to lower mRNA abundance of FASN and DGAT2 and TAG concentrations. Compared with fatty acid challenge alone, DGAT2 inhibitor + fatty acids led to greater mRNA and protein abundance of CPT1A, MTTP, and APOB, and lower mRNA and protein abundance of SREBF1 and FASN. In addition, compared with control and fatty acids, there was greater protein abundance of GRP78 and PERK in both DGAT1 and DGAT2 inhibitor with or without fatty acids. Furthermore, compared with control and fatty acids, reactive oxygen species concentrations in the DGAT1 inhibitor with or without fatty acid group was greater. Overall, data suggested that DGAT1 is particularly relevant in the context of hepatocyte TAG synthesis from exogenous fatty acids. Disruption of both DGAT1 and DGAT2 altered lipid homeostasis, channeling fatty acids toward oxidation and generation of reactive oxygen species. Both DGAT isoforms play a role in promoting fatty acid storage into TAG and lipid droplets to protect hepatocytes from oxidative damage.

Mipomersen in Familial Hypercholesterolemia: An Update on Health-Related Quality of Life and Patient-Reported Outcomes.

Familial hypercholesterolemia (FH) is an autosomal dominant condition that leads to significantly elevated low-density lipoprotein cholesterol (LDL-C) levels and an elevated risk for cardiovascular disease. Mipomersen is an antisense oligonucleotide inhibitor targeted to apolipoprotein B-100 (apoB-100) mRNA that is administered via subcutaneous injection. Once administered, mipomersen causes selective degradation of the apoB-100 mRNA and inhibition of protein translation. This ultimately results in substantial reductions in LDL-C and other lipoprotein levels. Mipomersen is approved for the treatment of homozygous FH. In this review, we discuss its mechanism, current evidence, limitations of use including adverse events, and impact on health-related quality of life.

CSF apolipoprotein B levels predict future visuospatial cognitive decline and synaptic pathology in cognitively unimpaired healthy elderly with a parental history of Alzheimer’s disease

AbstractBackgroundWe examine the role of brain apolipoprotein B (apoB) as a putative CSF indicator of early tau pathology in pre‐symptomatic Alzheimer’s disease (AD).MethodAmong 129 cognitively unimpaired elderly at increased risk of AD (PREVENT‐AD cohort), we assessed blood and cerebrospinal fluid apoB, apoC3 and apoE protein levels with those of amyloid β42, total tau and phosphorylated tau. We compared results with amyloid‐b (NAV4694) and tau (flortaucipir) positron emission tomography uptake and cognitive assessment alterations over 6‐8 years. Tangle and plaque pathologies were contrasted with cortical APOB, APOC3 and APOE mRNA levels in 240 autopsied subjects enrolled in the Religious Orders Study and Memory and Aging Project (ROSMAP) studies with diagnoses of cognitively unimpaired, mild cognitive impairment, or AD.ResultAmong cognitively unimpaired participants, we observed significant correlations between baseline CSF, but not blood, apoB levels and both CSF t‐tau (R2 = 0.23, P &lt; 0.0001) and P‐tau (R2 = 0.28, P &lt; 0.0001). Similar associations were observed when using PET flortaucipir‐binding in entorhinal, parahippocampal and fusiform regions. No association was detected between CSF apoB and CSF Aβ42 levels or cerebral Ab deposition. Baseline CSF apoB levels were associated with visuospatial cognitive decline over the course of 6‐8 years (R2 = 0.13, P &lt; 0.02) and alterations in several synaptic proteins in the CSF. Contribution from peripheral apoB was found to be negligible. In ROSMAP, APOB gene expression failed to correlate with either tangle pathology or amyloid plaque deposition.ConclusionCSF apoB markedly associates with early tau dysregulation in asymptomatic subjects and identifies at‐risk individuals predisposed to develop visuospatial cognitive decline over time.

The role of dynamin in absorbing lipids into endodermal epithelial cells of yolk sac membranes during embryonic development in Japanese quail

Endodermal epithelial cells (EECs) within the yolk sac membrane (YSM) of avian embryos are responsible for the absorption and utilization of lipids. The lipids in the yolk are mostly composed of very low density lipoprotein (VLDL), uptake mainly depends on clathrin-mediated endocytosis (CME). The CME relies on vesicle formation through the regulation of dynamin (DNM). However, it is still unclear whether DNMs participate in avian embryonic development. We examined mRNA expression levels of several genes involved in lipid transportation and utilization in YSM during Japanese quail embryonic development using qPCR. The mRNA levels of DNM1 and DNM3 were elevated at incubation d 8 and 10 before the increase of SOAT1, CIDEA, CIDEC, and APOB mRNA's. The elevated gene expression suggested the increased demand for DNM activity might be prior to cholesteryl ester production, lipid storage, and VLDL transport. Hinted by the result, we further investigated the role of DNMs in the embryonic development of Japanese quail. A DNM inhibitor, dynasore, was injected into fertilized eggs at incubation d 3. At incubation d 10, the dynasore-injected embryo showed increased embryonic lethality compared to control groups. Thus, the activity of DNMs was essential for the embryonic development of Japanese quail. The activities of DNMs were also verified by the absorptions of fluorescent VLDL (DiI-yVLDL) in EECs. Fluorescent signals in EECs were decreased significantly after treatment with dynasore. Finally, EECs were pretreated with S-Nitroso-L-glutathione (GSNO), a DNM activator, for 30 min; this increased the uptake of DiI-yVLDL. In conclusion, DNMs serve a critical role in mediating lipid absorption in YSM. The activity of DNMs was an integral part of development in Japanese quail. Our results suggest enhancing lipid transportation through an increase of DNM activity may improve avian embryonic development.

Pharmacokinetic-pharmacodynamic modeling for hepatic delivery and efficacy of antisense oligonucleotides with lipophilic ligands in mice.

Conjugation with lipophilic ligands such as cholesterol and α-tocopherol dramatically improves the delivery and efficacy of antisense oligonucleotides (ASOs) in the liver. To estimate the hepatic ASO concentration and the efficacy of ASOs conjugated with lipophilic ligands in mice, we constructed a pharmacokinetic-pharmacodynamic (PK-PD) model that consisted of a two-linear compartment model for the plasma and the hepatic ASO concentration, and two indirect response models for the hepatic apolipoprotein B (Apo-B) mRNA and plasma total cholesterol. The model provided a good fit of the hepatic ASO concentration although it showed an overprediction of Apo-B mRNA and an underprediction of the plasma total cholesterol within 2-fold at a later time after single intravenous administration of ASOs conjugated with lipophilic ligands. In addition, the model simulations indicated that the efficacy at a dose regimen of ASOs conjugated with lipophilic ligands (0.2mg/kg, once a week) in mice was comparable to that at an effective dose of unchanged ASO (2.5mg/kg, once a week). Although further studies are required to refine the parameters of the PK-PD model, this approach could be used to guide dose-ranging pharmacological studies for ASOs conjugated with lipophilic ligands in mice.

Apobec1 complementation factor overexpression promotes hepatic steatosis, fibrosis, and hepatocellular cancer.

The RNA-binding protein Apobec1 complementation factor (A1CF) regulates posttranscriptional ApoB mRNA editing, but the range of RNA targets and the long-term effect of altered A1CF expression on liver function are unknown. Here we studied hepatocyte-specific A1cf-transgenic (A1cf+/Tg), A1cf+/Tg Apobec1-/-, and A1cf-/- mice fed chow or high-fat/high-fructose diets using RNA-Seq, RNA CLIP-Seq, and tissue microarrays from human hepatocellular cancer (HCC). A1cf+/Tg mice exhibited increased hepatic proliferation and steatosis, with increased lipogenic gene expression (Mogat1, Mogat2, Cidea, Cd36) associated with shifts in polysomal RNA distribution. Aged A1cf+/Tg mice developed spontaneous fibrosis, dysplasia, and HCC, and this development was accelerated on a high-fat/high-fructose diet and was independent of Apobec1. RNA-Seq revealed increased expression of mRNAs involved in oxidative stress (Gstm3, Gpx3, Cbr3), inflammatory response (Il19, Cxcl14, Tnfα, Ly6c), extracellular matrix organization (Mmp2, Col1a1, Col4a1), and proliferation (Kif20a, Mcm2, Mcm4, Mcm6), and a subset of mRNAs (including Sox4, Sox9, Cdh1) were identified in RNA CLIP-Seq. Increased A1CF expression in human HCC correlated with advanced fibrosis and with reduced survival in a subset with nonalcoholic fatty liver disease. In conclusion, we show that hepatic A1CF overexpression selectively alters polysomal distribution and mRNA expression, promoting lipogenic, proliferative, and inflammatory pathways leading to HCC.

Familial Hypercholesterolaemia: An Updated Overall Management

Familial hypercholesterolaemia (FH), the commonest and serious but potentially treatable form of inherited dyslipidaemias, is characterised by severely elevated plasma low-density lipoprotein-cholesterol (LDL-C) level, which subsequently leads to premature coronary artery disease (pCAD). Effectiveness of FH early detection and treatment is supported by the outcome of several international cohort studies. Optimal FH management relies on prescription of statins either alone or together with other lipid-lowering therapies (LLT). Intensive lifestyle intervention is required in parallel with LLT, which should be commenced at diagnosis in adults and childhood. Treatment with high intensity statin should be started as soon as possible. Combination with ezetimibe and/or bile acid sequestrants is indicated if target LDL-C is not achieved. For FH patients in the very-high risk category, if their LDL-C targets are not achieved, despite being on maximally tolerated statin dose and ezetimibe, proprotein convertase subtilisin/kexin type1 inhibitor (PCSK9i) is recommended. In statin intolerance, ezetimibe alone, or in combination with PCSK9i may be considered. Clinical evaluation of response to treatment and safety are recommended to be done about 4-6 weeks following initiation of treatment. Homozygous FH (HoFH) patients should be treated with maximally tolerated intensive LLT and, when available, with lipoprotein apheresis. This review highlights the overall management, and optimal treatment combinations in FH in adults and children, newer LLT including PCSK9i, microsomal transfer protein inhibitor, allele-specific oligonucleotide to ApoB100 and PCSK9 mRNA. Family cascade screening and/or screening of high-risk individuals, is the most cost-effective way of identifying FH cases and initiating early and adequate LLT.

Fermented Rhus Verniciflua Stokes Extract Alleviates Nonalcoholic Fatty Liver through the AMPK/SREBP1/PCSK9 Pathway in HFD-Induced Nonalcoholic Fatty Liver Animal Model

Background: We have previously reported the anti-hepatic lipogenic effect of fermented Rhus verniciflua stokes extract (FRVE) in an oleic-acid-treated HepG2 cell model. Methods: Herein, we advanced our understanding and evaluated the impact of FRVE in HFD-fed C57BL/6 mice using an animal model of nonalcoholic fatty liver disease (NAFLD). Milk thistle extract was used as a positive control to compare the effects of FRVE. Results: FRVE decreased body weight, intra-abdominal fat weight, and liver weight. Furthermore, FRVE decreased HFD-induced elevated serum levels of ALT, AST, TC, and TG, and downregulated the increase in hepatic lipid accumulation and TG levels. FRVE reduced hepatic SREBP-1, PCSK-9, SREBP-2, and ApoB mRNA levels. IHC data showed that FRVE reduced the levels of nucleic SREBP-1, increased the levels of LDLR, and upregulated the expression of p-AMPK. Conclusion: Overall, these results demonstrate the anti-hepatic lipidemic effect of FRVE in an animal model. These findings are consistent with our previous study and strongly suggest that FRVE exerts anti-hepatic lipogenic effects by activating AMPK.

Low Expression of APOB mRNA or Its Hypermethylation Predicts Favorable Overall Survival in Patients with Low-Grade Glioma.

BackgroundThis study was performed to explore the clinical and prognostic significance of APOB mRNA expression, DNA methylation and APOB mutation in patients with low-grade glioma (LGG).MethodsBioinformatic analysis was conducted using genomic, clinical and survival data from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. Serum APOB protein levels were measured via immunoturbidimetry in 150 patients with LGG and 100 healthy controls from Hubei General Hospital.ResultsThere was a negative association between the levels of APOB mRNA and DNA methylation (r=−0.355, P<0.0001) in patients with LGG from the TCGA database. Additionally, LGG patients with low levels of APOB mRNA exhibited better overall survival (OS) than those with high levels of APOB mRNA (HR=0.637, P=0.0085). The survival time of LGG patients with APOB hypermethylation was markedly longer than that of patients with APOB hypomethylation (HR=0.423, P=0.0185). The prognostic significance of APOB mRNA and DNA methylation was also validated with the CGGA cohort, and a similar conclusion was reached. APOB gene mutations were observed in 3% of patients with LGG from the TCGA database, and no association was detected between APOB mutations and OS (P=0.164). Furthermore, the levels of APOB protein were much lower in patients with LGG than in normal individuals (P=0.0022), and the expression of APOB protein was markedly different among groups when stratified by histological type (P<0.0001) and histological-molecular classification (P<0.0001).ConclusionAPOB mRNA expression is negatively regulated by DNA methylation in patients with LGG. Low expression or hypermethylation of APOB might predict relatively favorable survival in patients with LGG.

Cell-Type–Specific, Ketohexokinase-Dependent Induction by Fructose of Lipogenic Gene Expression in Mouse Small Intestine

High intakes of fructose are associated with metabolic diseases, including hypertriglyceridemia and intestinal tumor growth. Although small intestinal epithelia consist of many different cell types, express lipogenic genes, and convert dietary fructose to fatty acids, there is no information on the identity of the cell type(s) mediating this conversion and on the effects of fructose on lipogenic gene expression. We hypothesized that fructose regulates the intestinal expression of genes involved in lipid and apolipoprotein synthesis, that regulation depends on the fructose transporter solute carrier family 2 member a5 [Slc2a5 (glucose transporter 5)] and on ketohexokinase (Khk), and that regulation occurs only in enterocytes. We compared lipogenic gene expression among different organs from wild-type adult male C57BL mice consuming a standard vivarium nonpurified diet. We then gavaged twice daily for 2.5 d fructose or glucose solutions (15%, 0.3 mL per mouse) into wild-type, Slc2a5-knockout (KO), and Khk-KO mice with free access to the nonpurified diet and determined expression of representative lipogenic genes. Finally, from mice fed the nonpurified diet, we made organoids highly enriched in enterocyte, goblet, Paneth, or stem cells and then incubated them overnight in 10 mM fructose or glucose. Most lipogenic genes were significantly expressed in the intestine relative to the kidney, liver, lung, and skeletal muscle. In vivo expression of Srebf1, Acaca, Fasn, Scd1, Dgat1, Gk, Apoa4, and Apob mRNA and of Scd1 protein increased (P<0.05) by 3- to 20-fold in wild-type, but not in Slc2a5-KO and Khk-KO, mice gavaged with fructose. In vitro, Slc2a5- and Khk-dependent, fructose-induced increases, which ranged from 1.5- to 4-fold (P<0.05), in mRNA concentrations of all these genes were observed only in organoids enriched in enterocytes. Fructose specifically stimulates expression of mouse small intestinal genes for lipid and apolipoprotein synthesis. Secretory and stem cells seem incapable of transport- and metabolism-dependent lipogenesis, occurring only in absorptive enterocytes.