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Principal Investigator: Nathalie Pamir
Organization: OREGON HEALTH & SCIENCE UNIVERSITY
Fiscal Year: 2021
Award: $517,392
Funding agency: National Heart Lung and Blood Institute
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a low-abundance plasma protein that reduces the expression of the LDL receptor (LDLR) and therefore plays a critical role in cholesterol trafficking. Its discovery revolutionized our understanding of cholesterol metabolism, shifting the homeostatic paradigm from a system where all the molecular determinants of cholesterol production and internalization are regulated by cellular responses, to one where the highest level of regulation is based extracellularly. Although the mechanism of action of PCSK9 on LDLR is well established, our understanding of the functional output and kinetic pathway of PCSK9 remains limited. We present preliminary results on three common post-translational modifications that alter PCSK9 and drive kinetic and functional changes: 1. Binding to apoB-containing lipoproteins (we now show that it prolongs plasma half-life of PCSK9 and increases its binding affinity to the LDLR); 2. Cleavage by furin (we now show that this is an extracellular event, and that furin-cleaved PCSK9 has accelerated clearance, impaired apoB-binding, and preserved ability to induce LDLR degradation intracellularly); and 3. N- glycosylation (we now show that non-glycosylated PCSK9 is less stable than its glycosylated form). Thus, the first aim of this competing renewal application focuses on how these post-translational modifications impact PCSK9 kinetics and function and affect cholesterol metabolism. Improved understanding of the global and net effect of plasma PCSK9 will open avenues for innovative diagnostic tools and tailored interventions to block PCSK9 action and lower plasma LDL cholesterol levels. Moreover, we have recently reported that therapeutic monoclonal antibodies inhibiting PCSK9 activity also induce a rapid and drastic (up to 20-fold) increase in plasma PCSK9 levels in patients receiving a few injections. This effect offers an opportunity to investigate the regulation of PCSK9 in plasma and to refine our knowledge of the turnover of this critical protein. We present preliminary data showing that the rise in plasma PCSK9 in humans occurs within a few hours after the first antibody injection, and can be reproduced in the mouse model, an observation that we will exploit for rigorous investigations of PCSK9 synthesis, secretion, processing, and clearance. Thus, the second aim of the program will elucidate the effect of plasma PCSK9 blockade on the regulation of hepatic PCSK9 synthesis or secretion in relation to its expected influence on PCSK9 clearance. Overall, the proposed work will provide an improved understanding of PCSK9 kinetics and activity on LDLR regulation, and may identify novel targets for pharmacologic inhibition of PCSK9.
Terms: <Affect><Affinity><Antibodies><Apo-B><ApoB><Apolipoproteins B><Binding><Biological><Biology><Blocking Antibodies><Blood Circulation><Blood Plasma><Bloodstream><Cardiac infarction><Cholesterol><Cholesterol Homeostasis><Circulation><Cleaved cell><Clinical Treatment Moab><Data><Diagnostic><Diagnostic tests><Drugs><Event><Generations><Genetic Alteration><Genetic Change><Genetic defect><Grant><Half-Life><Hepatic><Hour><Human><Hypercholesteremia><Impairment><In Vitro><Injections><Intervention><Intervention Strategies><Investigation><Kinetics><Knowledge><LDL><LDL Cholesterol><LDL Cholesterol Lipoproteins><LDL Lipoproteins><LDL Receptors><Length><Lipoprotein LDL Receptors><Lipoproteins><Liver><Low Density Lipoprotein Cholesterol><Low Density Lipoprotein Receptor><Low-Density Lipoproteins><MAb Therapeutics><Mediating><Medication><Metabolic><Metabolic Clearance Rate><Metabolic Glycosylation><Mice><Mice Mammals><Modeling><Modern Man><Modification><Molecular><Molecular Interaction><Monoclonal Antibodies><Murine><Mus><Mutation><Myocardial Infarct><Myocardial Infarction><N-Glycosylation Site><Output><Pathway interactions><Patients><Pharmaceutic Preparations><Pharmaceutical Preparations><Pharmacology><Plasma><Plasma Proteins><Plasma Serum><Play><Post-Translational Modification Protein/Amino Acid Biochemistry><Post-Translational Modifications><Post-Translational Protein Modification><Post-Translational Protein Processing><Posttranslational Modifications><Posttranslational Protein Processing><Production><Proprotein Convertases><Protein Cleavage><Protein Modification><Proteins><Proteolysis><Regulation><Reporting><Research><Reticuloendothelial System, Serum, Plasma><Risk><Role><Site><Solid><Structure><Subtilisins><System><Therapeutic Monoclonal Antibodies><Time><Work><base><beta-Lipoprotein Cholesterol><beta-Lipoproteins><cardiac infarct><cardiovascular risk><cardiovascular risk factor><cholesterol metabolism><cholesterol trafficking><clearance rate><cleaved><coronary attack><coronary infarct><coronary infarction><drug development><drug/agent><extracellular><genome mutation><glycosylation><heart attack><heart infarct><heart infarction><hepatic body system><hepatic organ system><high blood cholesterol><hypercholesterolemia><improved><inhibiting antibody><innovate><innovation><innovative><interventional strategy><mAbs><monoclonal antibody drugs><mouse model><murine model><new diagnostics><new drug treatments><new drugs><new therapeutics><new therapy><next generation diagnostics><next generation therapeutics><novel><novel diagnostics><novel drug treatments><novel drugs><novel therapeutics><novel therapy><pathway><preservation><programs><protein function><residence><residential building><residential site><response><social role><success><therapeutic mAbs><therapeutic target><tool>