Regulation mechanism of ABCA1 expression by statins in hepatocytes.

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Kobayashi M, Gouda K, Chisaki I, Ochiai M, Itagaki S, Iseki K

Regulation mechanism of ABCA1 expression by statins in hepatocytes.

Eur J Pharmacol. 2011 Jul 15;662(1-3):9-14. doi: 10.1016/j.ejphar.2011.04.043. Epub 2011 May 1.

PubMed ID

21554872 [ View in PubMed

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Abstract

ATP-binding cassette transporter A1 (ABCA1) is predicted to be involved in the control of apolipoprotein AI-mediated cholesterol efflux: biosynthesis of high-density lipoprotein (HDL). However, the effects of HMG-CoA reductase inhibitors (statins) on ABCA1 in the liver and the precise mechanisms of their actions have been obscure. The aims of this study were to determine whether statins (atorvastatin (Ato) and pitavastatin (Pit)) affect hepatic ABCA1 expression and to clarify the mechanisms of their actions using HepG2 cells and the rat liver. We examined alterations in mRNA and protein levels of ABCA1 and peroxisome proliferator-activated receptors (PPARs) by quantitative real-time polymerase chain reaction (PCR) and Western blot analysis, respectively. In vitro and in vivo studies suggested that Pit increases ABCA1 mRNA level, but not Ato. Pit greatly increased Abca1 mRNA level and also increased the amount of plasma HDL and the mRNA level of PPARalpha. Clofibrate (PPARalpha agonist) increased ABCA1 expression in HepG2 cells and rat primary hepatocytes more than did PPAR beta/delta and gamma agonists. Pit-induced ABCA1 expression alteration was blocked by GW6471 (PPARalpha antagonist) and by PPARalpha knockdown. In this study, we demonstrated that Pit affect ABCA1 expression via PPARalpha in hepatocytes. The strategy to target a PPARalpha agonist in the liver can lead to increases in ABCA1 expression and HDL level.