Ferri Nicola, Marchianò Silvia, Lupo Maria Giovanna, Trenti Annalisa, Biondo Giuseppe, Castaldello Paola, Corsini Alberto
Dipartimento di Scienze del Farmaco, Università degli Studi di Padova, Padua, Italy.
Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy.
Pharmacol Res. 2017 Aug;122:96-104. doi: 10.1016/j.phrs.2017.05.021. Epub 2017 May 26.
Statins are known to increase the plasma levels of proprotein convertase subtilisin kexin type 9 (PCSK9) through the activation of the sterol responsive element binding protein (SREBP) pathway due to the inhibition of cholesterol biosynthesis. In the present study, we explore a possible role of the prenylated proteins on the statin-mediated PCSK9 induction in Caco-2 cells. Simvastatin (40μM) induced both PCSK9 mRNA (10.7±3.2 fold) and protein (2.2±0.3 fold), after 24h incubation. The induction of PCSK9 mRNA was partially, but significantly, prevented by the co-incubation with mevalonate (MVA), farnesol (FOH) and geranylgeraniol (GGOH), while a complete prevention was observed on secreted PCSK9, evaluated by ELISA assay. Under the same experimental conditions, MVA, GGOH, but not FOH, prevented the activation of the PCSK9 promoter by simvastatin in a SRE-dependent manner. Simvastatin reduced by -35.7±15.2% the Rac1-GTP levels, while no changes were observed on RhoA- and Cdc42-GTP. This effect was prevented by MVA and GGOH. A Rac inhibitor, and N17Rac1 dominant negative mutant, significantly induced PCSK9 levels, and a suppression of Rac1 expression by siRNA, counteract the effect of simvastatin on the induction of PCSK9 mRNA. Finally, simvastatin, and Rac inhibitor inhibited the nuclear translocation of STAT3 and its knock-down by siRNA increased significantly the susceptibility of Caco-2 to simvastatin on PCSK9 expression. Taken together, the present study reveal a direct role of Rac1 on simvastatin-mediated PCSK9 expression via the reduction of STAT3 nuclear translocation.
已知他汀类药物通过抑制胆固醇生物合成激活固醇调节元件结合蛋白（SREBP）途径，从而增加前蛋白转化酶枯草溶菌素9型（PCSK9）的血浆水平。在本研究中，我们探讨了异戊二烯化蛋白在他汀类药物介导的Caco-2细胞中PCSK9诱导作用中的可能作用。辛伐他汀（40μM）孵育24小时后，诱导PCSK9 mRNA（10.7±3.2倍）和蛋白（2.2±0.3倍）表达。与甲羟戊酸（MVA）、法尼醇（FOH）和香叶基香叶醇（GGOH）共同孵育可部分但显著地阻止PCSK9 mRNA的诱导，而通过ELISA检测评估，对分泌型PCSK9则可完全阻止其诱导。在相同实验条件下，MVA、GGOH而非FOH以SRE依赖的方式阻止辛伐他汀对PCSK9启动子的激活。辛伐他汀使Rac1-GTP水平降低了-35.7±15.2%，而RhoA-和Cdc42-GTP水平未观察到变化。MVA和GGOH可阻止这种作用。一种Rac抑制剂和N17Rac1显性负突变体显著诱导PCSK9水平，通过siRNA抑制Rac1表达可抵消辛伐他汀对PCSK9 mRNA诱导的作用。最后，辛伐他汀和Rac抑制剂抑制STAT3的核转位，而通过siRNA敲低STAT3可显著增加Caco-2细胞对辛伐他汀诱导PCSK9表达的敏感性。综上所述，本研究揭示了Rac1通过降低STAT3核转位在辛伐他汀介导的PCSK9表达中起直接作用。
