Hepatocyte-specific IKK-β activation enhances VLDL-triglyceride production in APOE*3-Leiden mice

Abstract

Low-grade inflammation in different tissues, including activation of the nuclear factor κB pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular diseases (CVDs). In this study, we investigated the relation between chronic hepatocyte-specific overexpression of IkB kinase (IKK)-β and hypertriglyceridemia, an important risk factor for CVD, by evaluating whether activation of IKK-β only in the hepatocyte affects VLDL-triglyceride (TG) metabolism directly. Transgenic overexpression of constitutively active human IKK-β specifically in hepatocytes of hyperlipidemic APOE*3-Leiden mice clearly induced hypertriglyceridemia. Mechanistic in vivo studies revealed that the hypertriglyceridemia was caused by increased hepatic VLDL-TG production rather than a change in plasma VLDL-TG clearance. Studies in primary hepatocytes showed that IKK-β overexpression also enhances TG secretion in vitro, indicating a direct relation between IKK-β activation and TG production within the hepatocyte. Hepatic lipid analysis and hepatic gene expression analysis of pathways involved in lipid metabolism suggested that hepatocyte-specific IKK-β overexpression increases VLDL production not by increased steatosis or decreased FA oxidation, but most likely by carbohydrate-responsive element binding protein-mediated upregulation of Fas expression. These findings implicate that specific activation of inflammatory pathways exclusively within hepatocytes induces hypertriglyceridemia. Furthermore, we identify the hepatocytic IKK-β pathway as a possible target to treat hypertriglyceridemia. Low-grade inflammation in different tissues, including activation of the nuclear factor κB pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular diseases (CVDs). In this study, we investigated the relation between chronic hepatocyte-specific overexpression of IkB kinase (IKK)-β and hypertriglyceridemia, an important risk factor for CVD, by evaluating whether activation of IKK-β only in the hepatocyte affects VLDL-triglyceride (TG) metabolism directly. Transgenic overexpression of constitutively active human IKK-β specifically in hepatocytes of hyperlipidemic APOE*3-Leiden mice clearly induced hypertriglyceridemia. Mechanistic in vivo studies revealed that the hypertriglyceridemia was caused by increased hepatic VLDL-TG production rather than a change in plasma VLDL-TG clearance. Studies in primary hepatocytes showed that IKK-β overexpression also enhances TG secretion in vitro, indicating a direct relation between IKK-β activation and TG production within the hepatocyte. Hepatic lipid analysis and hepatic gene expression analysis of pathways involved in lipid metabolism suggested that hepatocyte-specific IKK-β overexpression increases VLDL production not by increased steatosis or decreased FA oxidation, but most likely by carbohydrate-responsive element binding protein-mediated upregulation of Fas expression. These findings implicate that specific activation of inflammatory pathways exclusively within hepatocytes induces hypertriglyceridemia. Furthermore, we identify the hepatocytic IKK-β pathway as a possible target to treat hypertriglyceridemia. Obesity is associated with diseases such as dyslipidemia, type 2 diabetes, and cardiovascular disease (CVD). The accumulation of lipids in numerous tissues is accompanied by increased inflammatory processes such as macrophage infiltration and production of inflammatory mediators in white adipose tissue. In liver, fat accumulation increases the activity of the pro-inflammatory nuclear factor κB (NF-κB), and liver-specific activation of NF-κB induces metabolic disturbances (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. Med. 2005; 11: 183-190Crossref PubMed Scopus (1799) Google Scholar, 2Arkan M.C. Hevener A.L. Greten F.R. Maeda S. Li Z.W. Long J.M. Wynshaw-Boris A. Poli G. Olefsky J. Karin M. IKK-beta links inflammation to obesity-induced insulin resistance.Nat. Med. 2005; 11: 191-198Crossref PubMed Scopus (1481) Google Scholar). Hypertriglyceridemia is caused by accumulation of VLDL particles in the plasma as a consequence of changes in lipid metabolism that are associated with obesity. Pro-inflammatory cytokines can cause hypertriglyceridemia (3Feingold K.R. Soued M. Adi S. Staprans I. Shigenaga J. Doerrler W. Moser A. Grunfeld C. Tumor necrosis factor-increased hepatic very-low-density lipoprotein production and increased serum triglyceride levels in diabetic rats.Diabetes. 1990; 39: 1569-1574Crossref PubMed Scopus (41) Google Scholar) and, conversely, suppression of inflammation may reduce hypertriglyceridemia (4Goldfine A.B. Silver R. Aldhahi W. Cai D. Tatro E. Lee J. Shoelson S.E. Use of salsalate to target inflammation in the treatment of insulin resistance and type 2 diabetes.Clin. Transl. Sci. 2008; 1: 36-43Crossref PubMed Scopus (243) Google Scholar) suggesting a direct causal role for inflammatory pathways in the development of hypertriglyceridemia. In fact, administration of lipopolysaccharide (LPS), an inflammatory component of the outer membrane of Gram-negative bacteria, increases plasma triglyceride (TG) levels (5Feingold K.R. Staprans I. Memon R.A. Moser A.H. Shigenaga J.K. Doerrler W. Dinarello C.A. Grunfeld C. Endotoxin rapidly induces changes in lipid metabolism that produce hypertriglyceridemia: low doses stimulate hepatic triglyceride production while high doses inhibit clearance.J. Lipid Res. 1992; 33: 1765-1776Abstract Full Text PDF PubMed Google Scholar). However, many inflammatory mediators affect multiple tissues, such as muscle, adipose tissue, and liver and, moreover, they can act on multiple cell types including macrophages. The specific contribution of hepatocytes in the relation between inflammation and TG metabolism has never been studied. In the current study, therefore, we aimed to investigate whether activation of the inflammatory NF-κB pathway exclusively in hepatocytes affects VLDL-TG metabolism and, as a consequence, causes hypertriglyceridemia. To this end, we used hepatocyte-specific transgenic IKK-β (LIKK) mice, which have been described before (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. Med. 2005; 11: 183-190Crossref PubMed Scopus (1799) Google Scholar). LIKK mice have an albumin promoter to drive expression of constitutively active human IκB kinase β (IKK-β), which activates the NF-κB pathway selectively in hepatocytes. To study the effects of the hepatocyte-specific inflammation on VLDL-TG metabolism, we crossbred the LIKK mouse with the transgenic APOE*3-Leiden (E3L) mouse that expresses human APOE*3-Leiden (a mutant form of APOE3) and human APOC1 (6van den Maagdenberg A.M. Hofker M.H. Krimpenfort P.J. de Bruijn I. van Vlijmen B.J. van der Boom H. Havekes L.M. Frants R.R. Transgenic mice carrying the apolipoprotein E3-Leiden gene exhibit hyperlipoproteinemia.J. Biol. Chem. 1993; 268: 10540-10545Abstract Full Text PDF PubMed Google Scholar), both of which attenuate the clearance of apolipoprotein (apo)E-containing TG-rich lipoproteins. Therefore, the E3L mouse shows increased plasma TG and cholesterol levels and is a well-established model of human-like lipoprotein metabolism (7Zadelaar S. Kleemann R. Verschuren L. de Vries-van der Weij J. van der Hoorn J. Princen H.M. Kooistra T. Mouse models for atherosclerosis and pharmaceutical modifiers.Arterioscler. Thromb. Vasc. Biol. 2007; 27: 1706-1721Crossref PubMed Scopus (436) Google Scholar). By using the E3L.LIKK mouse, we were able to study the effects of the inflammatory NF-κB pathway in the hepatocyte on TG-rich lipoprotein metabolism directly. Our results show that activation of NF-κB in hepatocytes of E3L mice induces hypertriglyceridemia by enhancing VLDL-TG production directly within hepatocytes. LIKK mice, which express constitutively active human IKK-β selectively in hepatocytes under control of the albumin promoter (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. Med. 2005; 11: 183-190Crossref PubMed Scopus (1799) Google Scholar), were crossbred with E3L mice (6van den Maagdenberg A.M. Hofker M.H. Krimpenfort P.J. de Bruijn I. van Vlijmen B.J. van der Boom H. Havekes L.M. Frants R.R. Transgenic mice carrying the apolipoprotein E3-Leiden gene exhibit hyperlipoproteinemia.J. Biol. Chem. 1993; 268: 10540-10545Abstract Full Text PDF PubMed Google Scholar), expressing both human APOE*3-Leiden and human APOC1, in our animal facility to obtain heterozygous E3L.LIKK mice on a C57Bl/6J background. Male E3L.LIKK and E3L littermates were housed under standard conditions with a 12 h light-dark cycle and were fed a standard mouse chow diet with free access to water. Experiments were performed on 14-week-old animals after an overnight fast. All experiments were approved by the institutional ethical committee on animal care and experimentation. Tissues were homogenized by Ultraturrax (22,000 rpm; 2 × 5 s) in an ice-cold buffer (pH 7.4) containing 30 mM Tris.HCl, 150 mM NaCl, 10 mM NaF, 1 mM EDTA, 1 mM Na3VO4, 0.5% (v/v) Triton X-100, 1% (v/v) SDS and protease inhibitors (Complete, Roche, Mijdrecht, The Netherlands) at a 1:6 (w/v) ratio. Homogenates were centrifuged (16,000 rpm; 15 min, 4°C) and the protein content of the supernatant was determined using the BCA protein assay kit (Pierce, Rockford, IL). Proteins (20–50 µg) were separated by 7–10% SDS-PAGE followed by transfer to a polyvinylidene fluoride (PVDF) membrane. Membranes were blocked for 1 h at room temperature in Tris-buffered saline with Tween-20 (TBST) with 5% nonfat dry milk followed by an overnight incubation with the following antibodies: p-Ser536 NF-κB p65 (#3031), NF-κB p65 (#3034), p-Ser32/36 IκBα (#9246), IκBα (#9242) (all from Cell Signaling), MTP (#612022) (BD Biosciences, Erembodegem, Belgium), and DGAT1 (#54037) (Abcam, Cambridge, UK). Blots were then incubated with HRP-conjugated secondary antibodies for 1 h at room temperature. Bands were visualized by ECL and quantified using Image J (National Institutes of Health). Blood was collected from the tail vein into chilled paraoxon (Sigma, St Louis, MO)-coated capillaries to prevent ongoing lipolysis (8Zambon A. Hashimoto S.I. Brunzell of to obtain plasma for of levels of free Lipid Res. 1993; Full Text PDF PubMed Google Scholar). were on and plasma was for cholesterol and using from were using kit from The the of lipid plasma of plasma was used for was a and at a of with TG and were as described in collected of were from to a from and of lipid and J. PubMed Scopus Google Scholar). a of liver was homogenized in ice-cold lipids were by of to The was and in Triton Hepatic TG and were using as described lipids were which was determined using the BCA protein assay were homogenized with 5 of by was containing In an TG standard was before lipids were to the of J. M. for the and of from animal Biol. Chem. Full Text PDF PubMed Google Scholar). TG were separated by lipid and in Lipid were visualized under after with and using TG were into and at with in for 2 were into and of the FA from liver TG was using on an with a 30 × 1 FA were by a containing FA were then TG-rich particles were and as described van M.C. J.K. van liver of by to Med. 1: PubMed Scopus Google Scholar, M.H. van M. van the of apolipoprotein for the hepatic in Lipid Res. Full Text PDF PubMed Google Scholar). at a of of with of were at 10 using a 150 UK). was used to obtain which were used for TG content of the was as described were at under and used within To study the in vivo clearance of the mice were by of The Mijdrecht, The and The were the tail vein with of particles at a of of TG Blood were from the tail vein at and 15 after and plasma was were as × as determined from clearance studies as described M.C. van der Boom H. van Havekes L.M. triglyceride by lipoprotein in and Lipid Res. Full Text Full Text PDF PubMed Google Scholar). the the liver, muscle, and white adipose and were were overnight at in Biosciences, The Netherlands) and was of by the was from the activity in by activity of and To VLDL production in mice were overnight and as described were with The Netherlands) to 30 at min, Triton was in to serum VLDL clearance. Blood were before and and after and used for of plasma TG as described min, mice were the and by VLDL was from serum after at by of plasma by PubMed Scopus Google Scholar) and for hepatocytes were from mouse to the of and of liver a and Cell Biol. PubMed Scopus Google Scholar) by van J.M. of in liver control of the in the pathway in the and of J. PubMed Scopus Google Scholar). the vein was and liver was with a buffer with and 5% at a of 5 of the liver was with buffer with for was were and centrifuged at for 1 at to from hepatocytes. hepatocytes were and in containing insulin and were with from of E3L.LIKK and E3L mice, as by and free of by with to were between from E3L.LIKK and E3L were into with at a of × in 2 a 2 h were from the by TG secretion in was as described M.C. M. R. Hofker M.H. H. secretion of low by apolipoprotein mouse PubMed Scopus Google Scholar). an overnight were and incubated h in and To of secretion of were incubated in and containing of with or mM with to stimulate or h was collected and were and in 2 were from to a from and of lipid and J. PubMed Scopus Google Scholar, M.C. M. R. Hofker M.H. H. secretion of low by apolipoprotein mouse PubMed Scopus Google Scholar). The lipids were under into with 2 mM as a and to using as Lipid were visualized using and were in and for by content of the was determined using the BCA protein assay kit as described are as was from liver tissues using the kit to of was by using analysis kit of was with kit and the was with kit was on the using the UK). levels were to levels of and are in I. are as were using the for with IL). was as To that LIKK expression in E3L mice increases hepatic NF-κB from E3L and E3L.LIKK mice were for the of NF-κB and IκBα using expression of LIKK increased the of NF-κB as as that of IκBα The increased of IκBα was caused by a of IκBα indicating increased IκBα and by the which activation of the NF-κB These are in with the increased NF-κB in LIKK mice as with mice (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. Med. 2005; 11: 183-190Crossref PubMed Scopus (1799) Google Scholar). To whether the hepatocyte-specific inflammation affects plasma lipid and levels were in plasma of E3L and E3L.LIKK mice LIKK expression in E3L mice increased TG by by and by LIKK not affect plasma levels showed that the in plasma TG by a in VLDL-TG the in was by an in VLDL cholesterol and Hypertriglyceridemia is caused by a in VLDL-TG clearance an in hepatic VLDL-TG To investigate whether LIKK the clearance of the plasma clearance and of TG-rich particles was in E3L.LIKK E3L mice LIKK not affect the plasma of the of by the indicating that LIKK not plasma TG levels by TG clearance. was in TG clearance between E3L.LIKK and E3L mice, is likely that the in plasma TG levels can by an of VLDL-TG The of hepatic VLDL-TG production was by plasma TG levels after Triton LIKK increased the accumulation of plasma TG at The VLDL-TG production as determined from the of the from mice, was increased by the of production not change VLDL a LIKK increases plasma TG levels by enhancing VLDL-TG production VLDL To investigate whether the in hepatic VLDL-TG production was the of increased lipid in the liver, the of LIKK on the hepatic lipid content was investigated However, E3L and E3L.LIKK mice not with to liver TG levels and levels LIKK not the FA of hepatic TG from a in the of by To whether IKK-β overexpression in hepatocytes directly increases VLDL-TG we TG secretion from hepatocytes of E3L and E3L.LIKK mice in used as for TG by the accumulation of in the In the of the secretion was but LIKK increased the secretion after h of incubation as with the secretion from control E3L hepatocytes In the of as a for TG secretion was and LIKK caused an in after h of incubation at To obtain into the the effects of IKK-β overexpression on VLDL-TG we the hepatic expression of involved in VLDL FA oxidation, cholesterol metabolism, metabolism, lipid and nuclear in of E3L and E3L.LIKK mice LIKK induced an of VLDL-TG production in vivo and in vitro, LIKK not affect hepatic gene expression or protein of TG transfer protein which is involved in the and secretion of In LIKK not affect in with the that LIKK not secretion in LIKK not affect expression of element binding protein which for de affect expression or protein levels of 1 which the and only in TG of LIKK on hepatic expression of involved in lipid metabolism in E3L secretion with the control metabolism with the control metabolism metabolism with the control with the control with the control were from E3L and E3L.LIKK was and expression of the was quantified by are as as with the control are not apolipoprotein cell protein cholesterol cholesterol 12 triglyceride transfer liver element binding with the control with the control in a were from E3L and E3L.LIKK was and expression of the was quantified by are as as with the control are not apolipoprotein cell protein cholesterol cholesterol 12 triglyceride transfer liver element binding In LIKK not affect of involved in FA 1 and cholesterol metabolism 5 and or metabolism and 12 from a in cholesterol expression. LIKK not affect of involved in lipid 2 protein and cell or expression of nuclear and liver from a in expression of 5 and However, LIKK expression of which a role in FA by and of kinase by both of which are target of carbohydrate-responsive element binding protein that LIKK increases VLDL-TG production by upregulation of Fas suggesting an in de Obesity to an in inflammatory processes in numerous including the liver in liver 2005; PubMed Scopus Google Scholar). In the current study, we whether increased activation of inflammatory pathways in the liver, specifically in induces hypertriglyceridemia. we show that chronic activation of the inflammatory NF-κB pathway specifically in hepatocytes increases plasma which was caused by an increased VLDL-TG production rather than a decreased clearance of Furthermore, we that the increased TG production induced by hepatocyte-specific IKK-β overexpression is a direct of the expression in the hepatocyte. The relation between inflammation and hypertriglyceridemia has been from the in plasma TG which is to to the W. Memon R.A. Shigenaga J.K. Moser A.H. K.R. Grunfeld C. of and inflammation on lipid and lipoprotein and to the Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). However, inflammatory pathways are metabolic inflammation is clearly different from inflammation with to and The inflammation that is in is a chronic and inflammation that is caused by a metabolic rather than a and metabolic PubMed Scopus Google Scholar). The NF-κB activity in the liver of E3L.LIKK mice in this study is with control E3L mice, which is to hepatic NF-κB activation levels after diet and in (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. Med. 2005; 11: 183-190Crossref PubMed Scopus (1799) Google Scholar). The study shows that this activation of hepatocyte-specific IKK-β induces an in plasma TG levels in E3L mice, a model for human-like lipoprotein metabolism, which was to an in plasma VLDL-TG of VLDL-TG metabolism revealed that the increased VLDL-TG levels were not caused by decreased clearance of TG from but rather by increased hepatic production of These findings are in with a study that of a low of increases secretion of clearance (5Feingold K.R. Staprans I. Memon R.A. Moser A.H. Shigenaga J.K. Doerrler W. Dinarello C.A. Grunfeld C. Endotoxin rapidly induces changes in lipid metabolism that produce hypertriglyceridemia: low doses stimulate hepatic triglyceride production while high doses inhibit clearance.J. Lipid Res. 1992; 33: 1765-1776Abstract Full Text PDF PubMed Google Scholar). However, with rather than with hepatocytes M. E. M. J. apolipoprotein lipopolysaccharide from to liver in in PubMed Scopus Google Scholar), which the of which cell type is for the in VLDL-TG In to cytokines that cell types VLDL-TG production (3Feingold K.R. Soued M. Adi S. Staprans I. Shigenaga J. Doerrler W. Moser A. Grunfeld C. Tumor necrosis factor-increased hepatic very-low-density lipoprotein production and increased serum triglyceride levels in diabetic rats.Diabetes. 1990; 39: 1569-1574Crossref PubMed Scopus (41) Google Scholar, Moser A.H. Staprans I. Grunfeld C. K.R. hepatic triglyceride secretion in PubMed Google Scholar). both and cytokines can NF-κB our findings that the in VLDL secretion caused by and cytokines in studies has been at in direct or activation of NF-κB in the hepatocytes. In the study, LIKK clearly increased VLDL-TG were effects of LIKK on production or hepatic gene expression. that NF-κB activation increases the of but not the of is in with a study by J. R. W. M. activation hepatic apolipoprotein for a between hepatic inflammation and lipoprotein J. PubMed Scopus Google Scholar) that overexpression of secretion in by the of which was with overexpression in in model than with transgenic overexpression in our in vivo is to that NF-κB activity increases of the VLDL a of NF-κB activation in the of is to the hepatocyte-specific NF-κB activation increases VLDL-TG as many different IKK-β overexpression can cause insulin resistance (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. Med. 2005; 11: 183-190Crossref PubMed Scopus (1799) Google Scholar), which in an of insulin to VLDL-TG production G. effects of insulin in the control of VLDL production in for the PubMed Scopus Google Scholar). Furthermore, have been suggested to an important role in hepatic lipid metabolism W. A. I. of liver the development of hepatic steatosis and insulin PubMed Scopus Google Scholar). cell lipid in hepatocytes suppression of activity R. C. S. van S. M. hepatic steatosis suppression of PubMed Scopus Google Scholar). Furthermore, plasma levels were by FA may have been resulting in for VLDL-TG Therefore, to the of IKK-β overexpression in hepatocytes on VLDL-TG production in of we the of IKK-β in hepatocytes on TG production in In fact, IKK-β expression in hepatocytes to directly VLDL-TG may to the of LIKK on VLDL-TG production in a direct of IKK-β overexpression in hepatocytes at to this and have to inflammation and with inflammatory processes S. of nuclear in inflammation and PubMed Scopus Google Scholar, R. S. W. C. E. S. M. The is a direct target gene of in 2007; Full Text Full Text PDF PubMed Scopus Google Scholar) and the by which hepatocyte-specific NF-κB activation increases VLDL-TG secretion directly within the hepatocyte. However, change was in expression of hepatic and or expression of target NF-κB activation but activation has been to a VLDL-TG secretion M. L. A. R.A. J. triglyceride levels a pathway and PubMed Scopus Google Scholar), a causal between activation and the in VLDL-TG secretion chronic hepatocyte-specific activation of NF-κB by IKK-β overexpression not changes in pathways that are in clearly increases VLDL-TG production and induces hypertriglyceridemia. hepatic lipid by increased decreased lipid oxidation, also the by which hepatocyte-specific NF-κB increases VLDL-TG inflammation has been to hepatic as by of into FA in vivo (5Feingold K.R. Staprans I. Memon R.A. Moser A.H. Shigenaga J.K. Doerrler W. Dinarello C.A. Grunfeld C. Endotoxin rapidly induces changes in lipid metabolism that produce hypertriglyceridemia: low doses stimulate hepatic triglyceride production while high doses inhibit clearance.J. Lipid Res. 1992; 33: 1765-1776Abstract Full Text PDF PubMed Google Scholar, K.R. Soued M. Moser A.H. Dinarello C.A. Grunfeld C. cytokines stimulate hepatic lipid in PubMed Scopus Google Scholar, C. R. Moser A.H. K.R. by which necrosis factor hepatic in Lipid Res. Full Text PDF PubMed Google Scholar). In our study, we expression of involved in hepatic FA and de the that LIKK not the expression of involved in FA oxidation, LIKK clearly increased expression of which is a in the of FA upregulation of Fas by the and R. and for of gene expression by liver Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, G. of protein as as Sci. PubMed Scopus Google Scholar), the upregulation of as a target gene that LIKK most likely activates Fas expression. The that activation of NF-κB has been to disturbances in metabolism that this (1Cai D. Yuan M. Frantz D.F. Melendez P.A. Hansen L. Lee J. Shoelson S.E. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF-kappaB.Nat. 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J. hepatic fat activates to and cholesterol 2005; 1: Full Text Full Text PDF PubMed Scopus Google Scholar) can by of TG into VLDL resulting in the increased hepatic VLDL-TG In we show that activation of hepatocyte-specific NF-κB overexpression of IKK-β increases TG levels in E3L mice by of VLDL-TG secretion directly within the hepatocyte effects on VLDL-TG clearance. The of VLDL-TG secretion is not by increased steatosis or decreased FA oxidation, but most likely by upregulation of Fas expression. The are to A. for with 5 1 apolipoprotein carbohydrate-responsive element binding protein cell protein cardiovascular disease cholesterol cholesterol 12 1 APOE*3-Leiden of κB IκB kinase β liver-specific IKK-β overexpression triglyceride transfer protein nuclear liver kinase 2 5 element binding protein cholesterol triglyceride white adipose