| 1992 |
ApoC-III overexpression in transgenic mice causes hypertriglyceridemia primarily by decreasing the fractional catabolic rate of VLDL particles, due to increased apoC-III and decreased apoE content on VLDL, leading to impaired hepatic receptor-mediated uptake rather than reduced lipoprotein lipase activity or substrate quality. |
Human apoC-III transgenic mouse lines, radiolabeled VLDL turnover studies, in vitro LPL assays, hepatoma cell uptake assays, primary hepatocyte secretion studies |
The Journal of clinical investigation |
High |
1430212
|
| 1996 |
ApoC-III on VLDL competitively displaces apoE, reducing lipoprotein receptor binding and heparin-sulfate proteoglycan interaction; addition of exogenous apoE rescues receptor binding, and crossbreeding apoC-III transgenic mice with apoE transgenic mice normalizes hypertriglyceridemia, demonstrating a functionally significant reciprocal relationship between apoC-III and apoE on triglyceride-rich lipoproteins. |
Transgenic mouse crossbreeding, fibroblast lipoprotein receptor binding assays, heparin-Sepharose binding assays, vitamin A fat tolerance test |
Journal of lipid research |
High |
8864964
|
| 1989 |
A 13-nucleotide element (C3P) in the apoCIII promoter is required for high-level hepatic expression and is sufficient to confer hepatic-specific expression to a heterologous promoter; a hepatic nuclear protein (AF-1) binds this element, and qualitative differences in C3P-binding proteins across cell types account for tissue-specific activity. |
Promoter deletion/mutation analysis, transient transfection in hepatic vs. non-hepatic cells, nuclear extract binding assays |
The Journal of biological chemistry |
High |
2777781
|
| 1990 |
The region -890 to -686 of the apoCIII promoter contains nuclear factor binding sites required for both hepatic and intestinal transcription; the region -686 to -553 is recognized by factors promoting only hepatic transcription; a proximal element (-86 to -74) is bound by two mutually exclusive factors (CIIIB1 suppressing transcription and CIIIB2 associated with normal transcription). |
Promoter deletion analysis, nucleotide substitution, DNase I footprinting with rat liver nuclear extracts, DNA binding and methylation interference assays, transient transfection in HepG2 and Caco-2 cells |
The Journal of biological chemistry |
High |
2161843
|
| 1992 |
HNF-4 activates APOC3 gene transcription by binding the CIIIB element (-87 to -63) of the proximal promoter, while ARP-1, EAR-2, and EAR-3 repress this same element; HNF-4 can reverse ARP-1-mediated repression, and the opposing effects result from competition for binding to the same regulatory element. Transcriptional activation by HNF-4 requires synergistic interaction with factors at upstream elements. |
Electrophoretic mobility shift assays, dissociation constant measurements, cotransfection experiments in HepG2 cells, promoter mutation analysis |
The Journal of biological chemistry |
High |
1639815
|
| 1994 |
Insulin transcriptionally down-regulates apoC-III gene expression; in streptozotocin-diabetic mice, apoC-III mRNA increases 1.4-1.5-fold and returns to normal with insulin treatment; nuclear run-on assays confirm this is a transcriptional effect; dose-dependent insulin suppression of apoC-III promoter activity is demonstrated in HepG2 transfection experiments. |
Streptozotocin mouse model, Northern blot, RNase protection assay, nuclear run-on transcription assay, HepG2 transfection with apoC-III reporter construct |
Journal of lipid research |
High |
7868970
|
| 1994 |
An NF-κB binding element located ~150 bp upstream of the apoCIII transcription start site binds NF-κB p50/p65 subunits; this element confers PMA- and IL-1β-inducible transcriptional activity to a heterologous promoter in HepG2 cells, but its inducible activity is suppressed by a distal apoCIII enhancer element ~500 bp upstream. |
Electrophoretic mobility shift assay with purified NF-κB and HepG2 nuclear extracts, antibody supershift with p50/p65 antibodies, transient transfection of heterologous promoter-reporter constructs in HepG2 cells |
Nucleic acids research |
High |
8036173
|
| 1995 |
The apoCIII distal enhancer contains multiple SP1 binding sites (elements F, H, I) and a specialized hormone response element (element G) recognized by ARP-1/EAR-3 but not HNF-4; SP1 and HNF-4 cooperate to achieve 10-fold enhancement of the proximal promoter; transcriptional activation requires an intact hormone response element on the proximal promoter. |
DNA binding assays, competition assays, supershift assays, transient transfection in HepG2 cells, promoter deletion and mutation analysis |
Biochemistry |
High |
7640286
|
| 1999 |
The MAP kinase signaling pathway regulates apoCIII transcription: inhibition of MEK increases apoCIII transcriptional activity 5-8-fold while activation decreases it 3-5-fold. The MAP kinase-responsive element maps to -740 in the apoCIII promoter and the major protein binding this site is HNF-4; MAP kinase inhibition increases HNF-4 mRNA and protein levels, indicating that MAP kinase controls apoCIII via regulation of HNF-4 expression. |
PD98059 MEK inhibitor and phorbol ester treatment of HepG2 cells, transient transfection with apoCIII promoter-reporter constructs, promoter deletion mapping, protein binding assays, HNF-4 mRNA and protein quantification |
The Journal of biological chemistry |
High |
10551874
|
| 1999 |
Ligand-dependent nuclear receptors RXRα/RARα, RXRα/T3Rβ, and PPARα bind apoCIII promoter hormone response elements; RXRα/RARα heterodimers increase apoCIII promoter activity ~2-fold with retinoid ligands while RXRα/T3Rβ represses it in the presence of T3. Different DR-motifs on elements B (DR-1), G (DR-5), and I4 (DR-1) are specifically recognized by distinct receptor combinations. |
DNA binding assays, methylation interference experiments, cotransfection in HepG2 cells with ligand treatment, promoter mutation analysis |
Biochemistry |
High |
9893992
|
| 1998 |
ATF-2 binds three regions of the apoCIII promoter and transactivates it ~1.6-fold; Jun family members (c-Jun, JunB, JunD) repress apoCIII transcription by interfering with the distal enhancer; ATF-2 and HNF-4 have additive positive effects on apoCIII transcription, and ATF-2 can counteract Jun-mediated repression. |
DNase I footprinting, cotransfection in HepG2 cells, promoter mutation analysis, synthetic promoter constructs |
Biochemistry |
High |
9760243
|
| 2000 |
SMAD3 and SMAD3-SMAD4 transactivate the apoCIII promoter 15-70-fold requiring an intact hormone response element; SMAD proteins physically interact with HNF-4 (demonstrated by co-immunoprecipitation and GST pull-down); SMAD-mediated transactivation is abolished when HNF-4 is suppressed by antisense ribozyme, indicating TGF-β/SMAD signaling regulates apoCIII via physical and functional interaction with HNF-4. |
Cotransfection in HepG2 cells, dominant-negative SMAD4, antisense ribozyme knockdown of HNF-4, co-immunoprecipitation, GST pull-down assay |
The Journal of biological chemistry |
High |
10995777
|
| 2000 |
A hormone response element in the apoCIII enhancer is essential for intestinal and renal expression of the apoA-I gene and for all detectable apoCIII gene expression in vivo; mutations in the apoCIII enhancer alone abolish intestinal apoA-I and apoCIII expression and reduce hepatic apoA-I by 80%. |
Transgenic mice carrying wild-type or enhancer-mutant apoA-I/apoCIII gene cluster, tissue-specific reporter (CAT) gene expression analysis |
The Journal of biological chemistry |
High |
10893424
|
| 2000 |
SP1 binding sites in the apoCIII enhancer are required for apoCIII gene expression; mutations in three SP1 sites reduce hepatic and intestinal CAT (apoCIII reporter) expression to 4% of control and reduce hepatic and intestinal apoA-I expression to 14% of control in transgenic mice. |
Transgenic mice carrying wild-type or SP1-site-mutant apoA-I/apoCIII gene cluster, tissue mRNA and reporter gene analysis |
Nucleic acids research |
High |
11121483
|
| 2002 |
Rev-erbα acts as a physiological repressor of apoC-III gene transcription by binding a Rev-erbα response element (AGGTCA half-site at -23/-18) downstream of the TATA box in the apoCIII promoter; Rev-erbα-deficient mice have elevated serum apoC-III mRNA, apoC-III protein, and VLDL triglycerides. |
Cotransfection in rat hepatocytes and RK13 cells, promoter deletion and mutation analysis, gel-shift experiments, Rev-erbα knockout mouse phenotype analysis |
Journal of lipid research |
High |
12454280
|
| 2004 |
Foxo1 mediates insulin suppression of apoC-III transcription: Foxo1 binds a consensus site in the apoC-III promoter and stimulates hepatic apoC-III expression; deletion or mutation of the Foxo1 binding site abolishes insulin response; adenoviral Foxo1 overexpression in mouse liver increases apoC-III expression and causes hypertriglyceridemia; constitutively active Foxo1 transgenic mice are hypertriglyceridemic; Foxo1 is deregulated (elevated, nuclear) in diabetic mice. |
Adenoviral gene transfer in mice, promoter binding assays, site-directed mutagenesis of Foxo1 binding site, constitutively active Foxo1 transgenic mice, NOD and db/db diabetic mouse models |
The Journal of clinical investigation |
High |
15546000
|
| 2010 |
PGC-1β transcriptional coactivator drives APOC3 expression through coactivating orphan nuclear receptor ERRα at the APOC3 gene cluster; liver-specific knockdown of APOC3 significantly ameliorates PGC-1β-induced hypertriglyceridemia; nicotinic acid reduces hepatic PGC-1β and APOC3 expression, and adenoviral knockdown of PGC-1β or APOC3 recapitulates nicotinic acid's hypolipidemic effect. |
Adenoviral knockdown in mouse liver, proteomic analysis of PGC-1β transcriptional complex, cotransfection assays, acute and chronic nicotinic acid treatment in mice |
Cell metabolism |
High |
20889132
|
| 2010 |
The missense APOC3 variant Ala23Thr (associated with human hypotriglyceridemia) impairs VLDL1 assembly; C3AT cells fail to assemble VLDL1 and accumulate TAG in microsomal IDL/LDL-like fractions, phenocopying brefeldin A treatment; the mutant protein is present in lumenal IDL/LDL but absent from VLDL fractions, suggesting the N-terminal region of apoC-III governs the second-step VLDL1 maturation by enabling lipid droplet-VLDL precursor fusion. |
Metabolic labeling of transfected McA-RH7777 cells, density gradient ultracentrifugation of secreted and lumenal lipoproteins, microsomal triglyceride transfer protein activity assay, brefeldin A comparison experiment |
Journal of lipid research |
High |
20097930
|
| 2011 |
The C-terminal lipid-binding domain of apoC-III (specifically positive charge at Lys58) is essential for apoC-III binding to lipid and for promoting TAG secretion; the K58E mutation abolishes lipid binding (demonstrated by Fat Western overlay) and abrogates apoC-III's ability to promote VLDL-TAG secretion and lumenal lipid droplet formation in hepatic cells and apoc3-null mice. |
Transfection of McA-RH7777 cells and adenoviral delivery in apoc3-null mice, metabolic labeling, Fat Western lipid-protein overlay assay, microsomal lumenal lipid droplet fractionation, charge-swap mutagenesis (K58E, K58R, K58E/K60E) |
The Journal of biological chemistry |
High |
21676879
|
| 2016 |
ApoC-III inhibits clearance of triglyceride-rich lipoproteins primarily through a hepatic mechanism mediated by LDL receptor (LDLR) and LRP1; antisense oligonucleotide reduction of apoC-III lowers plasma TGs in mice lacking LPL, HSPG receptors, LDLR, or LRP1 individually, but not in mice with combined deletion of LDLR and LRP1; apoC-III ASO has no effect on VLDL secretion or tissue lipid uptake. |
ApoC-III ASO treatment in multiple mouse knockout models (LPL-null, HSPG-null, LDLR-null, LRP1-null, LDLR/LRP1 double-null), postprandial clearance studies, lipoprotein injection experiments |
The Journal of clinical investigation |
High |
27400128
|
| 2017 |
The APOC3 A43T missense variant causes reduced circulating apoC-III due to impaired binding of the mutant protein to lipoproteins and accelerated renal catabolism of free apoC-III; the reduced apoC-III content in TRLs leads to accelerated TRL clearance. A monoclonal antibody targeting lipoprotein-bound apoC-III promotes its clearance and enhances TRL catabolism in vivo. |
Human heterozygote carriers studied, humanized mouse models expressing APOC3 A43T, in vivo TRL clearance studies, monoclonal antibody administration in mice |
Nature medicine |
High |
28825717
|
| 2019 |
ApoC-III inhibits LPL activity in tissues when apoE-mediated TRL clearance pathways (LDLR/LRP1 axis) are absent; in mice lacking both apoE and functional syndecan-1 HSPG, apoC-III ASO lowers plasma TG by increasing LPL activity in white adipose tissue without improving hepatic TRL clearance, demonstrating that apoE determines the mode of apoC-III action (receptor-mediated clearance vs. LPL inhibition). |
apoC-III ASO treatment in Apoe-/-Ndst1f/fAlb-Cre+ double-knockout mice, LPL activity assay in white adipose tissue, hepatic TRL clearance studies, clinical APOE isoform subgroup analysis |
Journal of lipid research |
High |
31092690
|
| 2019 |
ApoC-III glycoforms are differentially cleared by hepatic TRL receptors: HSPG preferentially clears disialylated apoC-III2, while LDLR/LRP1 preferentially clears monosialylated apoC-III1; in HSPG-deficient mice, relative apoC-III2 abundance increases and clearance is accelerated (t1/2=25 min vs. 55 min in WT); volanesorsen treatment correlates with increased apoC-III2/apoC-III1 ratio and decreased plasma TG. |
Human TRL injection into HSPG-deficient and LDLR/LRP1-double-knockout mice, mass spectrometry-based apoC-III glycoform quantification, patient plasma analysis after volanesorsen treatment |
Arteriosclerosis, thrombosis, and vascular biology |
High |
31390883
|
| 1987 |
ApoC-III is O-glycosylated at Thr74; a naturally occurring Thr74→Ala74 mutation (single nucleotide substitution A→G) prevents O-glycosylation of apoC-III, resulting in the un-glycosylated isoform apoC-III-0 found in elevated amounts in affected subjects. |
Molecular cloning of apoC-III gene from a subject with elevated apoC-III-0, DNA sequence analysis, AluI restriction site diagnosis |
Journal of lipid research |
High |
3123586
|
| 1988 |
O-linked glycosylation at Thr74 is not required for apoC-III secretion or lipid binding; site-directed mutagenesis of Thr74→Ala74 produces unglycosylated apoC-III that is secreted normally and associates with VLDL and HDL with similar affinity as wild-type apoC-III. |
Site-directed mutagenesis of apoC-III gene, stable cell transfection in C127 cells, pulse-chase analysis, density gradient ultracentrifugation of secreted protein |
The Journal of biological chemistry |
High |
3192519
|
| 2019 |
Intestinal apoC-III overexpression results in secretion of smaller, less dense chylomicron particles with reduced triacylglycerol secretion from the intestine; this effect is cell-autonomous as demonstrated in primary murine enteroid cultures. |
Primary murine intestinal enteroid cultures, apoC-III overexpression, lipoprotein density gradient fractionation, TAG secretion quantification |
Journal of lipid research |
Medium |
28159868
|
| 2019 |
ApoC-III on TRLs inhibits basolateral lipid substrate transport (BLST) in enterocytes; in vivo, high plasma apoC-III diverts dietary TAG from cytosolic lipid droplets toward mitochondrial fatty acid oxidation; in enteroid cultures, excess apoC-III on TRLs inhibits TAG uptake from TRLs on the basolateral surface and reduces mitochondrial respiration. |
ApoC-III transgenic mice, primary murine enteroids, Seahorse mitochondrial respiration assay, lipid droplet imaging, in vivo dietary fat tracing |
Journal of lipid research |
Medium |
31152000
|
| 2005 |
ApoC-III deficiency prevents apoE overexpression-induced hyperlipidemia in a gene-dose-dependent manner by alleviating apoE-induced inhibition of VLDL-TG hydrolysis; apoC-III is a more specific inhibitor of LPL activity than apoE in vitro; Apoc3 deficiency restores LPL-mediated fatty acid uptake in white adipose tissue in the context of 10-fold increased VLDL production. |
Adenoviral apoE4 overexpression in Apoe-/-, Apoc3+/-, and Apoc3-/- mice, LPL activity assay with VLDL-like emulsion particles, in vivo fatty acid uptake measurement in adipose tissue |
Journal of lipid research |
High |
15863838
|
| 2019 |
Individuals heterozygous for the APOC3 R19X null mutation have 49% lower apoC-III, lower plasma TG and VLDL-TG due to higher fractional clearance rates (not reduced production) of VLDL-TG and VLDL-apoB100; these subjects show higher conversion of VLDL remnants to LDL with little effect on direct hepatic VLDL remnant removal. |
Stable isotope (deuterium-labeled) kinetic studies of VLDL-TG and apoB100 in human R19X heterozygotes vs. unaffected siblings, VLDL-TG and apoB100 fractional clearance rate and production rate determination |
Arteriosclerosis, thrombosis, and vascular biology |
High |
30580564
|
| 2021 |
ApoC-III induces calcification in primary human valvular interstitial cells via a mitochondrial dysfunction/inflammation-mediated pathway; apoC-III is enriched in calcific vs. non-calcific aortic valve tissue and colocalizes with calcific regions in the fibrosa layer. |
Proteomics and immunohistochemistry of human aortic valve tissues, in vitro calcification assay in primary human valvular cell cultures with apoC-III treatment, mitochondrial dysfunction/inflammation pathway analysis |
The Journal of biological chemistry |
Medium |
33334888
|
| 2021 |
Guanidinylation of ApoC3 (gApoC3) is a post-translational modification occurring in CKD patients, induced by guanidine and urea; gApoC3 augments the pro-inflammatory effects of native ApoC3 on monocytes in vitro, promotes kidney fibrosis and impedes vascular regeneration in humanized mice. |
Mass spectrometry identification of guanidinylation in CKD patient samples, 2D-proteomics in CKD mouse model, in vitro monocyte stimulation, unilateral ureter ligation and vascular injury mouse models with humanized gApoC3 |
Journal of the American Society of Nephrology |
Medium |
34588185
|
| 2016 |
ApoC-III induces endothelial dysfunction through upregulation of TNF-α, which disrupts tight junctions by increasing JAM-1 expression, promotes leukocyte and platelet exudation, and increases THP-1 monocyte adhesion to HUVECs; siRNA silencing of TNF-α or JAM-1 abrogates APOC3-induced effects. |
ELISA, qRT-PCR, immunofluorescence, flow cytometry, transwell assay in HUVECs, siRNA silencing of TNF-α and JAM-1 |
Lipids in health and disease |
Medium |
27619170
|
| 2016 |
miR-424-5p directly targets the APOC3 3'UTR to suppress APOC3 expression; APOC3 activates the NF-κB signaling pathway in aortic smooth muscle cells; miR-424-5p upregulation or APOC3 silencing suppresses SMC proliferation, migration, and inflammation and promotes apoptosis through NF-κB pathway inactivation. |
Luciferase reporter assay confirming miR-424-5p binding to APOC3 3'UTR, gain/loss-of-function experiments in aortic smooth muscle cells, NF-κB pathway activity assays |
Experimental physiology |
Medium |
31912930
|
| 2016 |
A 3'UTR variant (rs4225) in APOC3 creates a functional miR-4271 binding site; the T allele suppresses APOC3 translation by facilitating miR-4271 binding while the G allele does not; subjects with the GG genotype have higher plasma APOC3 levels and the T allele is associated with decreased triglycerides. |
APOC3 3'UTR resequencing, luciferase reporter assay with miR-4271 co-transfection, case-control association study for CHD |
Scientific reports |
Medium |
27624799
|
| 2009 |
Incorporation of apoC-III into reconstituted HDL (rHDL) produces smaller particles with fewer apoA-I molecules, reduces LCAT activation in a dose-dependent manner, and enhances surfactant-like membrane disruption properties; rHDL with apoC-III increases MDA production in cell culture leading to increased cellular LDL uptake; cholesteryl ester transfer ability is unaffected by apoC-III content. |
Reconstituted HDL synthesis with defined apoA-I:apoC-III molar ratios, LCAT activity assay, CE transfer assay, DMPC lysis assay, cell culture LDL uptake with MDA measurement |
Molecules and cells |
Medium |
19326075
|
| 2022 |
In postprandial kinetic studies in humans with APOC3 loss-of-function mutations, reduced apoC-III markedly accelerates lipolysis of TG-rich lipoproteins and increases removal of VLDL remnants without affecting production rates of chylomicron apoB48, VLDL1, VLDL2, or LDL; concentrations of VLDL1, VLDL2, and IDL particles are substantially decreased. |
Stable isotope kinetic studies of apoB48 and apoB100 in chylomicrons, VLDL1, VLDL2, IDL, and LDL in LOF APOC3 mutation carriers vs. non-carriers, postprandial state |
JCI insight |
High |
36040803
|