Poster abstracts

Poster number 2 submitted by Dmitry Malyshka

Mimicking Permissive Cellular Conditions for Pathological Tau Aggregation

Dmitry Malyshka (Biological Chemistry and Pharmacology, The Ohio State University College of Medicine), Claire Hoffman (Biological Chemistry and Pharmacology, The Ohio State University College of Medicine), Jeff Kuret (Biological Chemistry and Pharmacology, The Ohio State University College of Medicine)

Abstract:
Background

Alzheimer’s disease is the leading cause of dementia in the world. It is defined in part by the presence of hyperphosphorylated tau fibrils within various brain regions, and yet the pathophysiology of this aberrant tau aggregation is still poorly understood. Researchers have studied tau aggregation extensively in vitro via the use negatively charged inducers and examined ex vivo-derived fibrils from multiple tauopathies via cryoelectron microscopy. Strikingly, tau adopts a unique yet consistent structural polymorph in each tauopathy despite sharing the same nucleating sequence. Taken together, this strongly indicates that polymorph structure is governed by disease-specific cellular conditions that induce aggregation.

Approach

We mimic potential permissive cellular conditions in vitro via the use of different tau aggregation inducers such as small molecule co-factors, negatively charged membranes, and tau hyperphosphorylation. After aggregation, we utilize cryoEM and recent advancements in helical reconstruction algorithms to achieve single-molecule resolution of the structured core of the resulting tau filaments.

Results

Over 6,000 cryoEM images of small molecule-induced tau filaments and over 2000 images of ODS-induced tau filaments were collected via the Titan Krios cryoEM microscope. All images were motion and CTF corrected before helical processing in RELION 3.1. Our data show that the backbone traces of our tau polymorphs are dissimilar from each other as well as from the published structures of the heparin-induced tau filaments.

Conclusions

Tau polymorph structure is heavily influenced by the nature of the inducer used for its aggregation. While it remains to be seen if any of these in vitro structures approximate ex vivo derived polymorphs, we plan to continue our efforts of achieving single molecule resolution with the existing datasets as well as for hyperphosphorylated-tau filaments.

Keywords: cryoEM, tau, aggregation