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Principal Investigator: Olga Gursky
Organization: BOSTON UNIVERSITY MEDICAL CAMPUS
Fiscal Year: 2020
Award: $427,652
Funding agency: National Institute of General Medical Sciences
PROJECT SUMMARY / ABSTRACT
The overall goal of this grant has been to understand in molecular details the action of apolipoproteins (apos)
and lipoproteins in health and disease. The current focus is on human apoA-I, the major protein of plasma
high-density lipoproteins (HDL, a.k.a. good cholesterol) that remove cholesterol from cells and protect against
cardiovascular disease. ApoA-I can be released from HDL in a labile lipid-poor/free state that is the precursor of
amyloid, and can cause two forms of systemic human amyloidosis. In the acquired form, apoA-I deposits in the
arteries as fibrils, which augments atherosclerosis. In the hereditary form, fragments of mutant apoA-I deposit
in vital organs (kidney, liver, nerves, etc.) and damage them. There is no cure for this life-threatening disease
and the only current treatment is organ transplant. To pinpoint therapeutic targets, we must understand what
determines the dynamic equilibrium between the generation of the amyloid precursor, its clearance, and its
misfolding, from the native helix-bundle structure in free apoA-I to the insoluble cross-β-sheet in amyloid.
Unraveling the complex process of protein misfolding and proteostasis to block systemic amyloidosis has been
very challenging but not impossible. To this end we have integrated high- and low-resolution structural and
spectroscopic methods (circular dichroism, fluorescence, hydrogen-deuterium exchange, etc.) with biochemical
and computational tools. Analysis of several disease-causing mutants enabled us to propose the first molecular
mechanism of apoA-I misfolding. We postulated that perturbed packing in amyloid `hot spots' combined with the
structural integrity of the native fold make the protein amyloidogenic. This idea can be extended to other
proteins; it helps explain why structural destabilization of many globular proteins is neither necessary nor sufficient
to cause amyloid disease. These and other new ideas will be rigorously tested in the next cycle of this grant.
Aim 1 will elucidate the molecular mechanism of apoA-I misfolding in hereditary amyloidosis. We will determine
how the disease-causing mutations perturb the native protein conformation in sensitive segments to promote
β-aggregation vs. proteolysis. Cell-based studies will unveil why mutation carriers are at a low risk of
atherosclerosis despite low levels of plasma HDL. Aim 2 will identify the similarities and differences in the
molecular basis for hereditary and acquired amyloidoses, and will establish the structure-toxicity relationship in
aggregated forms of apoA-I. Aim 3 will define the role of lipids in apoA-I misfolding. This aim will test our
hypothesis that lipid-lowering approaches hold therapeutic potential for apoA-I amyloidoses.
This research opens a new frontier that goes beyond protein stability to identify key drivers of protein misfolding
in vivo. The results will unveil the link between amyloidogenic and cardioprotective properties of apoA-I, help
find therapies for apoA-I amyloidoses, yield sharper insights into the misfolding of other apos that are prominent
in human amyloidoses, and have broad implications for misfolding diseases caused by other globular proteins.
Terms: <APOA2><ARGII protein><Abscission><Address><Adhesives><Aging><Amyloid><Amyloid Substance><Amyloidosis><Apo A-1><Apo A-2><Apo A-I><Apo A-II><Apo A1><Apo A2><Apo AI><Apo AII><ApoA-1><ApoA-2><ApoA-I><ApoA-II><Apolipoprotein A-1><Apolipoprotein A-2><Apolipoprotein A-I><Apolipoprotein A-II><Apolipoprotein A1><Apolipoprotein A2><Apolipoprotein AI><Apolipoprotein AII><Apolipoproteins><Apoplexy><Arterial Fatty Streak><Arterial Fatty Streaks><Arteries><Atheroma><Atheromatous><Atheromatous degeneration><Atheromatous plaque><Atheroscleroses><Atherosclerosis><Atherosclerotic Cardiovascular Disease><Automobile Driving><Beta Sheet><Binding><Biophysics><Blood Plasma><Brain Vascular Accident><C-terminal><Cardiac infarction><Cardiovascular Diseases><Cell Body><Cells><Cerebral Stroke><Cerebrovascular Apoplexy><Cerebrovascular Stroke><Cholesterol><Circular Dichroism><Complex><Crystallization><Data><Deposit><Deposition><Deuterium><Disease><Disorder><Equilibrium><Excision><Extirpation><Familial Amyloidosis><Fiber><Fluorescence><Free Fatty Acids><Generalized Growth><Generations><Genetic Alteration><Genetic Change><Genetic defect><Goals><Grafting Procedure><Grant><Growth><H element><H2 isotope><HDL><HDL Lipoproteins><Health><Heart><Heavy Lipoproteins><Hereditary><Hereditary Amyloidosis><High Density Lipoproteins><High density lipoprotein><Hot Spot><Human><Hydrogen><In Vitro><Inherited><Kidney><Kidney Urinary System><Kinetics><Lead><Length><Life><Ligands><Light><Link><Lipids><Lipoprotein (a)><Lipoprotein Lp(a)><Lipoproteins><Liver><Lp(a)><Mass Photometry/Spectrum Analysis><Mass Spectrometry><Mass Spectroscopy><Mass Spectrum><Mass Spectrum Analyses><Mass Spectrum Analysis><Methods><Modeling><Modern Man><Modification><Molecular><Molecular Configuration><Molecular Conformation><Molecular Dynamics Simulation><Molecular Interaction><Molecular Stereochemistry><Mutation><Myocardial Infarct><Myocardial Infarction><N-terminal><NH2-terminal><Nerve><Nonesterified Fatty Acids><Organ><Organ Transplantation><Organ Transplants><Pathogenicity><Patients><Pb element><Photoradiation><Plasma><Plasma Proteins><Plasma Serum><Process><Progress Reports><Property><Protein Cleavage><Protein Conformation><Proteins><Proteolysis><Public Health><Publications><Removal><Research><Resolution><Reticuloendothelial System, Serum, Plasma><Role><Scientific Publication><Skin><Stroke><Structure><Surface><Surgical Removal><Testicles><Testing><Testis><Therapeutic><Tissue Growth><Toxic effect><Toxicities><aberrant protein folding><abnormal protein folding><alpha-Lipoproteins><amyloid disease><apo(a)II protein><apolipoprotein(a)-related protein II><atheromatosis><atherosclerosis plaque><atherosclerosis risk><atherosclerotic disease><atherosclerotic lesions><atherosclerotic plaque><atherosclerotic risk><atherosclerotic vascular disease><balance><balance function><base><beta pleated sheet><biochemical tools><biochemistry tools><biophysical foundation><biophysical principles><biophysical sciences><brain attack><cardiac infarct><cardioprotectant><cardioprotection><cardioprotective><cardiovascular disorder><cerebral vascular accident><cerebrovascular accident><combat><computational tools><computerized tools><conformation><conformational state><coronary attack><coronary infarct><coronary infarction><disease-causing mutation><driving><frontier><gain of function><genome mutation><globular protein><heart attack><heart infarct><heart infarction><heavy metal Pb><heavy metal lead><hepatic body system><hepatic organ system><human disease><in vivo><insight><lipid nanoparticle><molecular dynamics><mutant><mutation carrier><novel><ontogeny><organ allograft><organ graft><organ xenograft><oxidation><pathologic protein folding><prevent><preventing><protein homeostasis><protein mis-folding><protein misfolding><proteostasis><renal><resection><scaffold><scaffolding><social role><therapeutic target><vulnerable plaque><β-Sheet><β-pleated sheet>