Abnormal (or mis-)folding alters protein's 3D conformation from native (soluble form) to non-native (insoluble from) polymorphic amyloid structures. Protein misfolding is linked to neurodegenerative (Alzheimer's, Huntington's, Parkinson's, familial dementia, prion encephalopathies), systemic (type II diabetes, light chain amyloidosis related cancer) and other (cystic fibrosis) diseases. Prevailing view suggests that protein misfolding-induced amyloids result into a gain-of-function and cause pathophysiologic cell response by destabilizing cell ionic homeostasis. Understanding protein misfolding and the resulting 3D conformations that induce pathophysiologic activity have been an important but challenging area of research. Mechanisms underlying amyloid fibril formation and its prevention are being studied extensively although amyloid fibers do not directly appear to cause neurodegenerative diseases; recent studies have shown that only globular amyloids are sufficient to cause pathophysiologic responses. The most direct mechanism of globular oligomer- mediated toxicity would involve their membrane poration as the key initial events. Our prevailing paradigm, therefore, is that protein misfolding diseases result from small globular amyloids forming ion channels to destabilize cell ionic homeostasis. Molecules and other interventions that modulate their channel structure and activity could thus be used for effective therapy. Indeed, amyloidogenic peptides induce ionic conductances in both native cell as well as artificial membranes. Structural study of membrane-bound amyloid complexes has been limited. Our studies have shown that amyloid peptides associated with several diseases form polymorphic ion channels. This continuing proposal primarily focuses on Alzheimer's disease (AD) linked amyloid beta (Ab) peptide that forms toxic channels. We intend to define the 3D structural polymorphism and identify amino acid (AA) epitopes in Ab peptide that can then be used as targets for designing effective therapeutics for AD. We will continue our multidimensional and complementary approaches of AFM imaging, ion conductance recording, molecular dynamics (MD) simulation, and cell Calcium uptake and degeneration to obtain a comprehensive understanding of amyloid ion channels.
Our Specific Aims are 1) Image 3D structure of synthetic as well as tissue-derived amyloidogenic peptides and peptides with site-specific amino acid (AA) substitutions reconstituted in lipid membrane; 2) Image open-closed conformations, in response to pharmacologic agents, of channels made of peptides, normal as well as with site-specific amino acid (AA) substitutions, 3) Correlate open-close channel conformations with ion conductance using integrated ion conductance AFM and pharmacologic agents and site-specific AA substitutions, and 4) Examine the cellular effects (e.g., calcium uptake and degeneration) of amyloid peptides. Our study will define specific amyloid structures underlying Alzheimer's and other degenerative pathophysiology and will identify specific structural motif(s) in amyloid ion channels that can then be used for designing pharmacological intervention of therapeutic value.

Public Health Relevance

Protein misfolding causes abnormal protein aggregates as amyloid plaques commonly associated with many devastating diseases, including Alzheimer's disease (AD). How these amyloids cause diseases is still unclear. Using complementary approaches of atomic force microscopy, electrophysiology, MD simulation and cell biology, our proposed work will identify the structural basis of AD pathology and define specific targets that can then be used for designing therapeutic and preventive strategies.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG028709-11
Application #
9232951
Study Section
Nanotechnology Study Section (NANO)
Program Officer
Refolo, Lorenzo
Project Start
2006-09-15
Project End
2018-02-28
Budget Start
2017-03-01
Budget End
2018-02-28
Support Year
11
Fiscal Year
2017
Total Cost
$254,901
Indirect Cost
$70,401
Name
University of California San Diego
Department
Type
Other Domestic Higher Education
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Hwang, Michael T; Wang, Zejun; Ping, Jinglei et al. (2018) DNA Nanotweezers and Graphene Transistor Enable Label-Free Genotyping. Adv Mater :e1802440
Martinez Hernandez, Ana; Urbanke, Hendrik; Gillman, Alan L et al. (2018) The diphenylpyrazole compound anle138b blocks A? channels and rescues disease phenotypes in a mouse model for amyloid pathology. EMBO Mol Med 10:32-47
Lee, Joon; Kim, Young Hun; T Arce, Fernando et al. (2017) Amyloid ? Ion Channels in a Membrane Comprising Brain Total Lipid Extracts. ACS Chem Neurosci 8:1348-1357
Wang, Liping; Jang, Grace; Ban, Deependra Kumar et al. (2017) Multifunctional stimuli responsive polymer-gated iron and gold-embedded silica nano golf balls: Nanoshuttles for targeted on-demand theranostics. Bone Res 5:17051
Liu, Mengmeng; Li, Qian; Liang, Le et al. (2017) Real-time visualization of clustering and intracellular transport of gold nanoparticles by correlative imaging. Nat Commun 8:15646
Gillman, Alan L; Lee, Joon; Ramachandran, Srinivasan et al. (2016) Small molecule NPT-440-1 inhibits ionic flux through A?1-42 pores: Implications for Alzheimer's disease therapeutics. Nanomedicine 12:2331-2340
Feinstein, H Eric; Benbow, Sarah J; LaPointe, Nichole E et al. (2016) Oligomerization of the microtubule-associated protein tau is mediated by its N-terminal sequences: implications for normal and pathological tau action. J Neurochem 137:939-54
Patel, Nirav; Ramachandran, Srinivasan; Azimov, Rustam et al. (2015) Ion Channel Formation by Tau Protein: Implications for Alzheimer's Disease and Tauopathies. Biochemistry 54:7320-5
Mo, Alexander H; Landon, Preston B; Emerson, Chris D et al. (2015) Synthesis of nano-bowls with a Janus template. Nanoscale 7:771-775
Landon, Preston B; Mo, Alexander H; Printz, Adam D et al. (2015) Asymmetric Colloidal Janus Particle Formation Is Core-Size-Dependent. Langmuir 31:9148-54

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