Molecular Bases of Proteinopathies

The Organizers

Invited Speakers

Presentations from Early Career Researchers - a mini-symposium (~March/April 2022)

Organizers of the ZOOMinar series invite early career researchers (students and post-doctoral fellows) to present their research related to "High-resolution structures of amyloid proteins". The goal is to provide opportunities for early-career researchers to present their latest research findings, interact with experts with multidisciplinary expertise, and gain critical feedback and collaborations.

To be considered for a short presentation in the ZOOMinar series, you will need to email a title, reference to a published paper, and graphics (or TOC figure) by Dec. 01, 2021. Emails: ramamoor@umich.edu; mivanova@umich.edu

*Additional details about this mini-symposium will be provide later.

April 11, 2022

Dr. Takahiro Watanabe-Nakayama

Kanazawa University

Japan

"Single molecule observation of amyloid aggregation"

Dr. Guido Pintacuda

Lyon University, France

"Conformational dynamics by NMR in crystals: a tool for detection aggregation propensity of folded and soluble proteins"

March 28, 2022

Dr. Marie Skepö

Lund University, Sweden

"Understanding the mechanism of interaction of the antimicrobial and antifungal saliva protein Histatin 5 with multivalent ions"

January 24, 2022

Dr. Jin Hyung Lee

Stanford University

"TBD"

December 06, 2021

Dr. Gregory Hudella

University of Florida

"TBD"

November 01, 2021

Professor Anant Paravastu

Georgia Institute of Technology

"Structural Studies of Alzheimer’s Amyloid-β Oligomers: why would a β-sheet peptide aggregate be limited in size?"

October 04, 2021 Dr. Dennis J. Selkoe

August 4, 2020

A Hypothesis for How Innate Immune Dysregulation May Cause Alzheimer’s Dementia;

and How We May Be Able to Prevent It

We are investigating the early-stage etiology of sporadic Alzheimer's Disease (AD), for which 420+ clinical trials by Pharma have failed over the past 15 years to produce an effective drug. What causes the accumulation of Aβ peptide-rich fibrils and plaques in an aging brain? What are Aβ's physiological functions? We focus on Aβ's interactions with the human cathelicidin peptide, LL-37, an antibacterial and antiviral innate immune system effector and modulator that is ubiquitous in tissues and expressed by myriad cell types, yet unique in the human proteome. Recently, evidence has built that chronic Herpesvirus or P. gingivalis infections of human brain tissue may precipitate many cases of sporadic dementia labeled as Alzheimer’s Disease. We present experimental evidence and discuss our developing hypothesis that the antiviral and antibacterial peptide LL-37, which can be chronically under-expressed in humans based on dietary and lifestyle factors or degraded by P. gingivalis virulence factors, is a natural binding partner of Aβ that inhibits formation of AD fibrils and plaques, such that LL-37 and Aβ have a toxin/antitoxin relationship. We demonstrate binding between LL-37 and Aβ by Transmission Electron Microscopy (TEM), Surface Plasmon Resonance Imaging (SPRi), and circular dichroism (CD) spectroscopy. TEM shows that LL-37 inhibits the fibrillization of Aβ, especially the formation of long, straight fibrils characteristic of AD, while CD spectroscopy reveals that LL-37 binding prevents Aβ from adopting β-type secondary structure. Analytical Ultracentrifugation (AUC) and Small-Angle X-ray Scattering (SAXS) prove that LL-37 and Aβ form a unique, water-soluble, 1:1 complex. In vitro cell culture studies using primary human microglia and neuronal cells indicates that these two peptides neutralize each other’s cytotoxic effects on these cells. Finally, studies in 5XFAD and wildtype transgenic mice, and Drosophila Melanogaster, support these findings. We discuss what all of this means in the context of the prevention and treatment of Alzheimer’s dementia.

September 12, 2020

“Entry to peptide Wonderland through the rabbit-hole”

September 19, 2020

“IAPP cross interactions: from discovery to exploitation"

September 26, 2020

“New insights into tau prion propagation”

October 3, 2020

“Pathogenic vs Reversible Functional Amyloid"

October 17, 2020

“Distinct species of amyloid oligomers and their biological activities”

October 24, 2020

“The complex landscape of α-synuclein”

November 14, 2020

“How chaperones regulate protein phase transition and its role in neurodegenerative disease”

February 06, 2021

"Metabolite Self-Assembly: Extension of the amyloid hypothesis"

"Heterogeneity of Aβ Aggregates"

Communications Biology volume 4, Article number: 120 (2021).

The thermodynamic hypothesis of protein folding, known as the “Anfinsen’s dogma” states that the native structure of a protein represents a free energy minimum determined by the amino acid sequence. However, inconsistent with the Anfinsen’s dogma, globular proteins can misfold to form amyloid fibrils, which are ordered aggregates associated with diseases such as Alzheimer’s and Parkinson’s diseases. Here, we present a general concept for the link between folding and misfolding. We tested the accessibility of the amyloid state for various proteins upon heating and agitation. Many of them showed Anfinsen-like reversible unfolding upon heating, but formed amyloid fibrils upon agitation at high temperatures. We show that folding and amyloid formation are separated by the supersaturation barrier of a protein. Its breakdown is required to shift the protein to the amyloid pathway. Thus, the breakdown of supersaturation links the Anfinsen’s intramolecular folding universe and the intermolecular misfolding universe.

No ZOOMinar

on March 27th and April 3rd

Enjoy the break!

Tata Institute of Fundamental Research,

Mumbai 400005, INDIA

Email: maiti@tifr.res.in, URL: biophotonics.co.in

“Probing toxic protein oligomers: From test tubes to patient-derived neurons”

Understanding how amyloid aggregates actually become toxic is one of the challenges in developing a treatment for diseases such as Alzheimer’s and Parkinson’s. One of the major possibilities is that the small oligomeric aggregates incorporate into the cell membrane and make specific functional structures which ultimately cause toxicity. However, very little is known about the structure of the oligomers, the stoichiometry of the toxic oligomer, its insertion into the membrane, and subsequent cellular interactions. Perhaps the hardest problem is to establish the correlation of all these parameters with the actual disease. Here we address these issues for Amyloid-beta, which is associated with Alzheimer’s disease. Nature has provided some clues for Alzheimer’s in terms of the location of disease-accelerating mutations, correlations with other protein isoforms, and neuron-type specific vulnerabilities. However, they have been hard to interpret. Using tools such as nanosecond FCS, time resolved FRET, solid state NMR, membrane-mediated SERS, single molecule photobleaching, and Alzheimer’s patient-derived neurons, we are finally making sense of some of these clues.

References:

1) Dey et al., Chem. Eur. J., (2021), https://doi.org/10.1002/chem.202100328

2) Dey et al., Physical Chemistry Chemical Physics (2020) 22 (26), 14613

3) Chandra et al., Chemical Communications (2018) 54 (56), 7750-7753

4) Bhowmik et al., ACS Nano (2015), 9 (9), 9070-9077

5) Sarkar et al., Angewandte Chemie (2014) 126 (27), 6948-6948.

"Seeing the molecular details of amyloid formation"

"A short motif in the N-terminal region of alpha-synuclein is critical for aggregation"

“Role of α-synuclein phosphorylation at serine 129 in the pathogenesis of synucleinopathies: an active debate"

Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) are human neurodegenerative diseases characterized neuropathologically by the presence of neuronal α-synuclein inclusions, named as Lewy bodies and Lewy neurites. Increasing number of studies highlighted the aberrant accumulation of phosphorylated α-synuclein at the residue Serine129 (pS129) in the brain of PD and DLB patients, suggesting that phosphorylation may play a vital role in the regulation of α-synuclein aggregation and subsequent neuronal degeneration. However, a comprehensive understating of the exact role of α-synuclein phosphorylation at S129 is still lacking. Here, we study the time-point at which pS129 modification occurs in the process of α-synuclein aggregation and its role in initiation, progression and cellular toxicity of the disease. Therefore, with the collaboration of many international teams we have addressed this issue by designing and executing important in vitro, ex vivo, and in vivo experiments using various models, in addition to post-mortem human brain studies. Contrary to the putative view of pS129-α-synuclein being particularly disease-relevant form of α-synuclein, we suggest that pS129 diminished aggregation-propensity, attenuated cytotoxicity, and occurs subsequent to initial α-synuclein aggregation. Our novel findings have important implications for the design of future neuropathological studies and the development of therapeutic approaches targeting of distinct α-synuclein species.

"In-cell NMR: a powerful approach for studying protein folding and maturation"

"The structural biology of protein misfolding in Huntington’s disease"

Michel Goedert

Professor, MRC Laboratory of Molecular Biology, Cambridge, UK

mg@mrc-lmb.cam.ac.uk

“Cryo-EM structures of amyloid filaments from human brain"

July 3, 2021: No Zoominar

"Islet amyloid polypeptide a friend or foe to the beta-cell"