Statins Upregulate PCSK9, the Gene Encoding the Proprotein Convertase Neural Apoptosis-Regulated Convertase-1 Implicated in Familial Hypercholesterolemia

Laboratory of Hyperlipidemia and Atherosclerosis Research Group, Clinical Research Institute of Montreal, Quebec, Canada.
Arteriosclerosis Thrombosis and Vascular Biology (Impact Factor: 6). 09/2004; 24(8):1454-9. DOI: 10.1161/01.ATV.0000134621.14315.43
Source: PubMed


Neural apoptosis-regulated convertase (NARC)-1 is the newest member of the proprotein convertase family implicated in the cleavage of a variety of protein precursors. The NARC-1 gene, PCSK9, has been identified recently as the third locus implicated in autosomal dominant hypercholesterolemia (ADH). The 2 other known genes implicated in ADH encode the low-density lipoprotein receptor and apolipoprotein B. As an approach toward the elucidation of the physiological role(s) of NARC-1, we studied its transcriptional regulation.
Using quantitative RT-PCR, we assessed NARC-1 regulation under conditions known to regulate genes involved in cholesterol metabolism in HepG2 cells and in human primary hepatocytes. We found that NARC-1 expression was strongly induced by statins in a dose-dependent manner and that this induction was efficiently reversed by mevalonate. NARC-1 mRNA level was increased by cholesterol depletion but insensitive to liver X receptor activation. Human, mouse, and rat PCSK9 promoters contain 2 typical conserved motifs for cholesterol regulation: a sterol regulatory element (SRE) and an Sp1 site.
PCSK9 regulation is typical of that of the genes implicated in lipoprotein metabolism. In vivo, PCSK9 is probably a target of SRE-binding protein (SREBP)-2.

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Available from: Hanny Wassef, Jul 29, 2014
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    • "The most common cause of cellular cholesterol deficiency is treatment with a statin agent [10]. Thus, although those taking statins experience a large LDL-C reduction due to the over-expression of LDLR, it is likely that this effect is diminished by the concomitant increase in PCSK9 [11] [12]. The parallel expression pattern of PCSK9 and LDLR is represented in Fig. 1A. "
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    ABSTRACT: Proprotein convertase subtilisin kexin type 9 (PCSK9) is a circulatory ligand that terminates the lifecycle of the low-density lipoprotein (LDL) receptor (LDLR) thus affecting plasma LDL-cholesterol (LDL-C) levels. Recent evidence shows that in addition to the straightforward mechanism of action, there are more complex interactions between PCSK9, LDLR and plasma lipoprotein levels, including: (a) the presence of both parallel and reciprocal regulation of surface LDLR and plasma PCSK9; (b) a correlation between PCSK9 and LDL-C levels dependent not only on the fact that PCSK9 removes hepatic LDLR, but also due to the fact that up to 40% of plasma PCSK9 is physically associated with LDL; and (c) an association between plasma PCSK9 production and the assembly and secretion of triglyceride-rich lipoproteins.
    Full-text · Article · Dec 2014 · Atherosclerosis
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    • "Because they reduce intracellular cholesterol, statins induce feedback up-regulation of nuclear sterol regulatory element-binding protein 2 (SREBP-2), the transcription factor that drives cholesterol biosynthesis. This factor also activates transcription of the LDLR and PCSK9 genes [13]. The coordinated up-regulation of these two functionally opposing genes limits the therapeutic efficacy of statins. "
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    ABSTRACT: Low-density lipoprotein receptor (LDLR) mediates hepatic clearance of plasma cholesterol; proprotein convertase subtilisin/kexin 9 (PCSK9) opposes this clearance by promoting LDLR degradation. The plant flavonoid quercetin-3-β-D-glucoside (Q3G) has been shown to reduce hypercholesterolemia in experimental animals. Here, we examined how it affects LDLR and PCSK9 expression as well as LDL uptake by human Huh7 hepatocytes. At low micromolar concentrations, Q3G increased LDLR expression, reduced PCSK9 secretion, and stimulated LDL uptake. It also diminished intracellular sortilin, a sorting receptor known to facilitate PCSK9 secretion. Thus, as an LDLR inducer and a PCSK9 anti-secretagogue, Q3G may represent an effective anti-cholesterolemic agent.
    Full-text · Article · Sep 2014 · FEBS Open Bio
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    • "To determine whether PCSK9 levels are associated with CAD, we performed a logistic regression analysis correcting for known CAD risk factors (Table 3). However, given the known marked effect of statins [6], [20] and fibrates [21], [22] to elevate PCSK9 levels, also seen in our study (Table 2), we stratified the analysis by statin use. PCSK9 levels were only associated with CAD in individuals taking a statin (Table 3, p = 0.0003), suggesting that the observed effect of CAD on PCSK9 levels (Table 2) is driven by higher statin use among CAD cases. "
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    ABSTRACT: Objective Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a circulating protein that promotes degradation of the low density lipoprotein (LDL) receptor. Mutations that block PCSK9 secretion reduce LDL-cholesterol and the incidence of myocardial infarction (MI). However, it remains unclear whether elevated plasma PCSK9 associates with coronary atherosclerosis (CAD) or more directly with rupture of the plaque causing MI. Methods and Results Plasma PCSK9 was measured by ELISA in 645 angiographically defined controls (<30% coronary stenosis) and 3,273 cases of CAD (>50% stenosis in a major coronary artery) from the Ottawa Heart Genomics Study. Because lipid lowering medications elevated plasma PCSK9, confounding association with disease, only individuals not taking a lipid lowering medication were considered (279 controls and 492 with CAD). Replication was sought in 357 controls and 465 with CAD from the Emory Cardiology Biobank study. PCSK9 levels were not associated with CAD in Ottawa, but were elevated with CAD in Emory. Plasma PCSK9 levels were elevated in 45 cases with acute MI (363.5±140.0 ng/ml) compared to 398 CAD cases without MI (302.0±91.3 ng/ml, p = 0.004) in Ottawa. This finding was replicated in the Emory study in 74 cases of acute MI (445.0±171.7 ng/ml) compared to 273 CAD cases without MI (369.9±139.1 ng/ml, p = 3.7×10−4). Since PCSK9 levels were similar in CAD patients with or without a prior (non-acute) MI, our finding suggests that plasma PCSK9 is elevated either immediately prior to or at the time of MI. Conclusion Plasma PCSK9 levels are increased with acute MI.
    Full-text · Article · Sep 2014 · PLoS ONE
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