Role of the N- and C-Terminal Domains in Binding of Apolipoprotein E Isoforms to Heparan Sulfate and Dermatan Sulfate: A Surface Plasmon Resonance Study

Yamauchi, Yuko; Deguchi, Noriko; Takagi, Chieko; Tanaka, Masafumi; Dhanasekaran, Padmaja; Nakano, Minoru; Handa, Tetsurou; Phillips, Michael C.; Lund‐Katz, Sissel; Saito, Hiroyuki

doi:10.1021/bi8003999

Cited by 41 publications

(35 citation statements)

References 59 publications

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“…We further found that endogenous PCSK9 from conditioned media of HepG2 cells also bound heparin (Supplementary Fig. 3a ) and showed similar elution profile as that of ApoE, a well-established HSPG-binding protein 19 . To determine if the predicted HSPG-binding motif in PCSK9 is responsible for heparin binding, we cloned and expressed PCSK9 variants in which combinations of the six amino acids were substituted for alanine (A) (Supplementary Fig.…”

Section: Resultsmentioning

confidence: 58%

Heparan sulfate proteoglycans present PCSK9 to the LDL receptor

et al. 2017

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Coronary artery disease is the main cause of death worldwide and accelerated by increased plasma levels of cholesterol-rich low-density lipoprotein particles (LDL). Circulating PCSK9 contributes to coronary artery disease by inducing lysosomal degradation of the LDL receptor (LDLR) in the liver and thereby reducing LDL clearance. Here, we show that liver heparan sulfate proteoglycans are PCSK9 receptors and essential for PCSK9-induced LDLR degradation. The heparan sulfate-binding site is located in the PCSK9 prodomain and formed by surface-exposed basic residues interacting with trisulfated heparan sulfate disaccharide repeats. Accordingly, heparan sulfate mimetics and monoclonal antibodies directed against the heparan sulfate-binding site are potent PCSK9 inhibitors. We propose that heparan sulfate proteoglycans lining the hepatocyte surface capture PCSK9 and facilitates subsequent PCSK9:LDLR complex formation. Our findings provide new insights into LDL biology and show that targeting PCSK9 using heparan sulfate mimetics is a potential therapeutic strategy in coronary artery disease.

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Section: Resultsmentioning

confidence: 58%

Heparan sulfate proteoglycans present PCSK9 to the LDL receptor

et al. 2017

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“…Protein modification, oligomerization, and structure configuration of apoE may also modulate the receptor binding. ApoE is a glycosylated protein with at least two glycosylation sites and also forms different oligomers (20,42,80,81,84,86). ApoE on the HCV virions appears to be hyperglycosylated compared to apoE expressed in the cell and secreted to supernatant (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Hepatitis C Virus Attachment Mediated by Apolipoprotein E Binding to Cell Surface Heparan Sulfate

Jiang

Wei

et al. 2012

J Virol

149

160

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cViruses are known to use virally encoded envelope proteins for cell attachment, which is the very first step of virus infection. In the present study, we have obtained substantial evidence demonstrating that hepatitis C virus (HCV) uses the cellular protein apolipoprotein E (apoE) for its attachment to cells. An apoE-specific monoclonal antibody was able to efficiently block HCV attachment to the hepatoma cell line Huh-7.5 as well as primary human hepatocytes. After HCV bound to cells, however, antiapoE antibody was unable to inhibit virus infection. Conversely, the HCV E2-specific monoclonal antibody CBH5 did not affect HCV attachment but potently inhibited HCV entry. Similarly, small interfering RNA-mediated knockdown of the key HCV receptor/coreceptor molecules CD81, claudin-1, low-density lipoprotein receptor (LDLr), occludin, and SR-BI did not affect HCV attachment but efficiently suppressed HCV infection, suggesting their important roles in HCV infection at postattachment steps. Strikingly, removal of heparan sulfate from the cell surface by treatment with heparinase blocked HCV attachment. Likewise, substitutions of the positively charged amino acids with neutral or negatively charged residues in the receptor-binding region of apoE resulted in a reduction of apoE-mediating HCV infection. More importantly, mutations of the arginine and lysine to alanine or glutamic acid in the receptor-binding region ablated the heparin-binding activity of apoE, as determined by an in vitro heparin pulldown assay. HCV attachment could also be inhibited by a synthetic peptide derived from the apoE receptor-binding region. Collectively, these findings demonstrate that apoE mediates HCV attachment through specific interactions with cell surface heparan sulfate. H epatitis C virus (HCV) is a leading cause of liver diseases, chronically infecting an estimated 130 million to 170 million people worldwide (71, 82). HCV infection results in acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma (59), which ranks as the fifth most common cancer and the third most frequent cause of cancer death worldwide. Hepatitis C is also the most common indication for liver transplantation (15). Coinfection of HCV and HIV is very common, particularly among drug abusers (3). Thus, HCV infection poses a major global health problem. Current standard therapy with pegylated alpha interferon (peg-IFN-␣) and ribavirin is less than 50% effective against HCV genotype 1, the dominant virus accounting for up to 70% of infections (27,41,54). Although two HCV NS3 protease-specific inhibitors, telaprevir and boceprevir, have recently been approved (33), their combination with peg-IFN-␣ and ribavirin has limitations such as severe side effects, long duration of treatment, and high cost. Discovery and development of more efficacious and safer anti-HCV drugs are urgently needed.HCV is the prototype virus of the Hepacivirus genus in the Flaviviridae family (68). It is an enveloped RNA virus containing a single positive-strand RNA genome that encodes...

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“…SPR has been employed successfully to measure the binding of apoE to proteoglycans (12–15) and members of the LDL receptor family (16), and of enzymes to lipoprotein particles (17;18). The present results show that apoE binds by a two-step mechanism to HDL and VLDL.…”

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confidence: 99%

Molecular Mechanism of Apolipoprotein E Binding to Lipoprotein Particles

et al. 2009

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The exchangeability of apolipoprotein (apo) E between lipoprotein particles such as very low density lipoprotein (VLDL) and high density lipoprotein (HDL) is critical for lipoprotein metabolism but, despite its importance, the kinetics and mechanism of apoE-lipoprotein interaction are not known. We have used surface plasmon resonance (SPR) to monitor in real time the reversible binding of apoE to human VLDL and HDL3; biotinylated lipoproteins were immobilized on a streptavidin-coated SPR sensor chip and solutions containing various human apoE molecules at different concentrations were flowed across the surface. Analysis of the resultant sensorgrams indicated that the apoE3/lipoprotein interaction is a two-step process. After an initial interaction, the second slower step involves opening of the N-terminal helix bundle domain of the apoE molecule. Destabilization of this domain leads to more rapid interfacial rearrangement as is seen when comparing the lipoprotein binding of apoE4 relative to that of apoE3. The resultant differences in interfacial packing seem to underlie the differing abilities of apoE4 and apoE3 to bind to VLDL and HDL3. The measured dissociation constants for apoE binding to these lipoprotein particles are in the micromolar range. C-terminal truncations of apoE to remove the lipid binding region spanning residues 250–299 reduces binding to both types of lipoprotein but the effect is less with HDL3; this suggests that protein-protein interactions are important for apoE binding to this lipoprotein while apoE-lipid interactions are more significant for VLDL binding. The two-step mechanism of lipoprotein binding exhibited by apoE is likely to apply to other members of the exchangeable apolipoprotein family.

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Role of the N- and C-Terminal Domains in Binding of Apolipoprotein E Isoforms to Heparan Sulfate and Dermatan Sulfate: A Surface Plasmon Resonance Study

Cited by 41 publications

References 59 publications

Heparan sulfate proteoglycans present PCSK9 to the LDL receptor

Heparan sulfate proteoglycans present PCSK9 to the LDL receptor

Hepatitis C Virus Attachment Mediated by Apolipoprotein E Binding to Cell Surface Heparan Sulfate

Molecular Mechanism of Apolipoprotein E Binding to Lipoprotein Particles

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