PCSK9 binds to multiple receptors and can be functionally inhibited by an EGF-A peptide

Department of Cardiovascular and Metabolic Disease Research, Schering-Plough Research Institute, 2015 Galloping Hill Road, K-15-1/1945, Kenilworth, NJ 07033, USA.
Biochemical and Biophysical Research Communications (Impact Factor: 2.3). 11/2008; 375(1):69-73. DOI: 10.1016/j.bbrc.2008.07.106
Source: PubMed


Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low density lipoprotein receptor (LDLR) and induces its internalization and degradation. PCSK9 binding to LDLR is mediated through the LDLR epidermal growth factor-like repeat A (EGF-A) domain. We show for the first time that an EGF-A peptide inhibits PCSK9-mediated degradation of LDLR in HepG2 cells. In addition to LDLR, we show that PCSK9 also binds directly to ApoER2 and mouse VLDLR. Importantly, binding of PCSK9 to either LDLR or mouse VLDLR was effectively inhibited by EGF-A while binding to ApoER2 was less affected. In contrast, LDL receptor-associated protein (RAP), which interacts with LDL receptor repeat type A (LA) domains, inhibited PCSK9 binding to ApoER2 with greater efficacy than either LDLR or mVLDLR. These data demonstrate that while PCSK9 binds several receptors via its EGF-A binding domain, additional contacts with other receptor domains are also involved.

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Available from: Nicholas John Murgolo, Mar 20, 2015
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    • "hesis , EGF - A2 and EGF - A3 showed non - saturatable binding to PCSK9 in surface plasmon resonance ( SPR ) up to 400 µM , whereas the dissociation constant ( K D ) of EGF - A4 for PCSK9 ( 1 . 18 µM ) was similar to that of the wild type EGF - A1 ( 1 . 01 µM ; Table 1 ; Figure S3 ) and comparable to that observed for EGF - A in a previous study ( Shan et al . , 2008 ) ."
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    ABSTRACT: Disrupting the binding interaction between proprotein convertase (PCSK9) and the epidermal growth factor-like domain A (EGF-A domain) in the low-density lipoprotein receptor (LDL-R) is a promising strategy to promote LDL-R recycling and thereby lower circulating cholesterol levels. In this study, truncated 26 amino acid EGF-A analogs were designed and synthesized, and their structures were analyzed in solution and in complex with PCSK9. The most potent peptide had an increased binding affinity for PCSK9 (KD = 0.6 μM) compared with wild-type EGF-A (KD = 1.2 μM), and the ability to increase LDL-R recycling in the presence of PCSK9 in a cell-based assay.
    Chemistry & biology 01/2014; 21(2). DOI:10.1016/j.chembiol.2013.11.014 · 6.65 Impact Factor
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    • "The crystal structure of PCSK9 in complex with the EGF-A domain revealed that the binding site resides on the surface of PCSK9’s catalytic domain but at more than 20 Å away from the catalytic site (Figure 4A).55 Autocatalysis at position Q152 releases a newly available amine group (−NH2) at a distance of 27 Å, forming a hydrogen bond with D299 of the LDLR (Figure 4C).55 Other residues directly involved in the avidity of PCSK9:LDLR interface are R194:D310, D238:N295, D374:H306, and T377:N309 (Figure 4C and D).55 Remarkably, it was shown that PCSK9 binds similarly to other LDLR family members (very LDLR [VLDLR] and ApoER2; Figure 4B)80 and that EGF-A peptides antagonize PCSK9 binding to LDLR and VLDLR (Figure 4B and Table 1).79–81 Although EGF-A is a relatively weak antagonist, a phage-display approach has revealed peptidic combinations with greatly improved affinity to PCSK9 (Table 1).82 "
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    ABSTRACT: Proprotein convertase subtilisin/kexin type 9 (PCSK9) directly binds to the epidermal growth factor-like repeat A domain of low-density lipoprotein receptor and induces its degradation, thereby controlling circulating low-density lipoprotein cholesterol (LDL-C) concentration. Heterozygous loss-of-function mutations in PCSK9 can decrease the incidence of coronary heart disease by up to 88%, owing to lifelong reduction of LDL-C. Moreover, two subjects with PCSK9 loss-of-function mutations on both alleles, resulting in a total absence of functional PCSK9, were found to have extremely low circulating LDL-C levels without other apparent abnormalities. Accordingly, PCSK9 could represent a safe and effective pharmacological target to increase clearance of LDL-C and to reduce the risk of coronary heart disease. Recent clinical trials using anti-PCSK9 monoclonal antibodies that block the PCSK9:low-density lipoprotein receptor interaction were shown to considerably reduce LDL-C levels by up to 65% when given alone and by up to 72% in patients already receiving statin therapy. In this review, we will discuss how major scientific breakthroughs in PCSK9 cell biology have led to the development of new and forthcoming LDL-C-lowering pharmacological agents.
    Drug Design, Development and Therapy 10/2013; 7:1135-1148. DOI:10.2147/DDDT.S36984 · 3.03 Impact Factor
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    • "An alternative approach for inhibiting the PCSK9 LDLR interaction may be the use of small peptide mimicking the EGF-A/B domain of LDLR [66, 70]. The validity of this approach has been also confirmed by using HepG2 cells overexpressing EGF-A [88]. "
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    ABSTRACT: The identification of the HMG-CoA reductase inhibitors, statins, has represented a dramatic innovation of the pharmacological modulation of hypercholesterolemia and associated cardiovascular diseases. However, not all patients receiving statins achieve guideline-recommended low density lipoprotein (LDL) cholesterol goals, particularly those at high risk. There remains, therefore, an unmet medical need to develop additional well-tolerated and effective agents to lower LDL cholesterol levels. The discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9), a secretory protein that posttranscriptionally regulates levels of low density lipoprotein receptor (LDLR) by inducing its degradation, has opened a new era of pharmacological modulation of cholesterol homeostasis. This paper summarizes the current knowledge of the basic molecular mechanism underlying the regulatory effect of LDLR expression by PCSK9 obtained from in vitro cell-cultured studies and the analysis of the crystal structure of PCSK9. It also describes the epidemiological and experimental evidences of the regulatory effect of PCSK9 on LDL cholesterol levels and cardiovascular diseases and summarizes the different pharmacological approaches under development for inhibiting PCSK9 expression, processing, and the interaction with LDLR.
    09/2012; 2012(14):927352. DOI:10.6064/2012/927352
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