α-Tocopherol modulates the low density lipoprotein receptor of human HepG2 cells

Pal, Sebely; Thomson, A. D.; Bottema, Cynthia D.K.; Roach, Paul D.

doi:10.1186/1475-2891-2-3

Cited by 21 publications

(9 citation statements)

References 47 publications

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“…Increased cholesterol synthesis is associated with a downregulation of LDLr activity and may thus decrease TRL uptake (Pedersen et al 2000). In addition, a-tocopherol has been reported to upregulate mRNA expression and activity of the LDLr in the human liver cell line HepG2 (Pal et al 2003). The higher rate of uptake of HOSO-compared with VOO-or EVO-TRL cannot, however, be explained by the tocopherol content, since the enrichment of the unsaponifiable fraction in EVO increases the level of tocopherols above that of HOSO, but the relatively low content of squalene in HOSO compared with VOO and EVO may play a part.…”

Section: Discussionmentioning

confidence: 99%

Uptake of triacylglycerol-rich lipoproteins of differing triacylglycerol molecular species and unsaponifiable content by liver cells

et al. 2006

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The fatty acid composition of dietary oils can modulate the incorporation of triacylglycerol-rich lipoproteins (TRL) into hepatocytes, thus affecting the atherogenicity of these particles. However, nothing is known about the effect of the unsaponifiable fraction of the oils. In the present study, we evaluated the influence of these components on the uptake of TRL by rat primary hepatocytes. TRL were isolated from human serum after the intake of meals enriched in high-oleic sunflower oil (HOSO), virgin olive oil (VOO) or VOO enriched in its own unsaponifiable fraction (EVO). HOSO and HOSO-TRL differed from VOO and EVO and their corresponding TRL in the composition of triacylglycerol molecular species and of the unsaponifiable fraction. Furthermore, the increase in the unsaponifiable fraction of VOO led to changes in the triacylglycerol molecular species in the EVO-TRL. On incubation with hepatocytes, HOSO-TRL were taken up at a faster rate than VOO-TRL or EVO-TRL. In addition, in comparison to VOO-TRL, HOSO-TRL increased the expression of mRNA for the LDL receptor-related protein receptor, which plays an important role in the internalisation of remnant lipoproteins. EVO-TRL also increased LDL receptor-related protein mRNA expression in comparison with VOO-TRL, but this change was not accompanied by a rise in the uptake rate, suggesting that the unsaponifiable fraction of VOO may inhibit LDL receptor-related protein expression or activity post-transcriptionally. In conclusion, TRL from dietary oils with differing triacylglycerol molecular species and unsaponifiable fraction content are taken up by liver cells at different rates, and this may be important in the atherogenicity of these particles.

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Section: Discussionmentioning

confidence: 99%

Uptake of triacylglycerol-rich lipoproteins of differing triacylglycerol molecular species and unsaponifiable content by liver cells

et al. 2006

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“…Also, a similar trend was true for PPARg gene, since its expression was respectively 1.2-, 1.3-and 1.8-fold higher than that of control. ARE exhibits this particular biological activity similar to that of a-tocopherol, which has been demonstrated to function in a concentration-dependent fashion with a biphasic 'up then down' effect on LDLR in HepG2 cells (Pal et al, 2003). In particular, at low levels of a-tocopherol (up to 50 µM), LDLR binding activity, protein and mRNA were progressively induced to maximum levels, while they gradually decreased to baseline levels at concentrations higher than 50 µM.…”

Section: Discussionmentioning

confidence: 89%

Effects of Thai black sticky rice extract on oxidative stress and lipid metabolism gene expression in HepG2 cells

Sangkitikomol

Tencomnao²,

Rocejanasaroj³

2010

Genet. Mol. Res.

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ABSTRACT. Anthocyanins, which are found in some food, including Thai black sticky rice, are reported to have health-promoting properties. Oxidative stress plays a major role in the pathogenesis of many degenerative diseases induced by free radicals, such as cardiovascular disease, stroke and cancer. We evaluated the anthocyanin-rich extract (ARE) from Thai black sticky rice for antioxidative and antihyperlipidemic effects on HepG2 cells. Cell viability was investigated with the neutral red assay and the MTT assay, and oxidative stress was determined by the DCFH-DA assay. RT-PCR was used to evaluate the effect of ARE on LDLR, HMG-CoAR, PPAR (a1,g) and LXRa gene expression. We found that ARE at high doses (>800 mg/L) induces cytotoxicity. However, at 600-1000 mg/L it reduced intracellular oxidative stress (P < 0.05) in a dose-dependent manner, and at 200 mg/L 2087 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 9 (4): 2086-2095 (2010) Antioxidant and antihyperlipidemic effects of black rice it significantly enhanced the expression of the LDLR gene in HepG2 cells. We concluded that ARE can be beneficial for health promotion by reducing oxidative stress and enhancing LDL clearance, regulating LDLR production on the cell surface membrane, thereby maintaining lipid homeostasis.

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“…Although inhibition of LDL oxidation by a range of different plant sources has been reported (Salleh, Runnie, Roach, Mohamed, & Abeywardena, 2002), relatively few studies have focused on the effects of phytochemicals on LDLR activity (Lovati et al, 1992;Pal, Thomson, Bottema, & Roach, 2003). However, the molecular mechanism of the plasma cholesterol lowering effect by the VRF has not been reported.…”

Section: Discussionmentioning

confidence: 98%

Vanillin rich fraction regulates LDLR and HMGCR gene expression in HepG2 cells

Al-Naqeb

Ismail

Bagalkotkar

et al. 2010

Food Research International

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Vanillin and its analogs have been exploited for their various health benefits. This work aimed to investigate the antioxidant properties and regulatory effects of vanillin rich fraction (VRF) extracted from vanilla pods using the supercritical fluid extraction (SFE) and commercial vanillin on low density lipoprotein receptor (LDLR) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) gene expression in HepG2 cells. The vanillin content in the VRF was 2.6% (w/w) obtained at a temperature of 80°C and a pressure of 600 bar. The VRF exhibited better antioxidant activity compared to the vanillin in DPPH and BCB tests. LDLR mRNA level was increased significantly by 2, 3 and 1.3 fold in the VRF treated cells at 100, 200 and vanillin treated cells at 100, respectively, compared with untreated cells. On the other hand, the HMGCR mRNA level was decreased significantly by 14, 58 and 13% respectively, in the VRF treated cells at 100, 200 and V treated cells at 100, respectively, compared with untreated cells. The VRF showed potential antioxidant activity and regulated genes involved in cholesterol metabolism including LDLR and HMGCR in dose-dependent manner.

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α-Tocopherol modulates the low density lipoprotein receptor of human HepG2 cells

Cited by 21 publications

References 47 publications

Uptake of triacylglycerol-rich lipoproteins of differing triacylglycerol molecular species and unsaponifiable content by liver cells

Uptake of triacylglycerol-rich lipoproteins of differing triacylglycerol molecular species and unsaponifiable content by liver cells

Effects of Thai black sticky rice extract on oxidative stress and lipid metabolism gene expression in HepG2 cells

Vanillin rich fraction regulates LDLR and HMGCR gene expression in HepG2 cells

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