Tau Aggregation Assay

Background of Tau Aggregation

Tau proteins are a group of proteins encoded by microtubule associated protein tau (MAPT) gene, which are primarily distributed in astrocytes of the central nervous system. Tau is involved in microtubule assembly and stabilization, neuronal morphology, iron export, and axonal transportation. However, the dysfunction of tau could lead to a series of neurodegenerative disorders, such as Alzheimer's disease (AD). The aggregation of neurofibrillary tau tangles in the cytoplasm, especially pairs of helical filaments (PHF), are cytotoxic to neurons, which are one of the hallmarks of AD. Tau proteins do not spontaneously aggregate under either normal physiological or extreme conditions, as the tau aggregation interface exists in hydrophilic interactions. Pathological tau aggregation can spread to normal neurons and lead to fibrillization of tau and ulterior aggregation. Therefore, Creative Biolabs offers reliable in vitro tau aggregation assay services for our global clients to assist in the mechanism of action studies and therapeutic exploration.

Tau Aggregation Assays at Creative Biolabs

Appropriate tau aggregation assays at Creative Biolabs could help researchers to assess the extent of tau aggregation and to capture the conformational alterations at different time points of tau aggregation. Single-molecule fluorescence resonance energy transfer (Single-molecule FRET) is a biophysical technology that can measure intramolecular distances and has been employed to measure tau conformational alterations with or without aggregation inducers.

Fig.1 Diagram of microfluidic channel and single-molecule FRET set-up. (Shammas, et al., 2015)

High molecular weight heparins are capable of inducing tau aggregation in vitro. Highly reproducible fluorescence spectroscopy assays are technologies that can evaluate the intramolecular distances and structural alteration of tau proteins at several time points during aggregation by the detection of Thioflavin T fluorescence intensity at an appropriate excitation and emission wavelength.

Fig. 2 Thioflavin T fluorescence probes the formation of tau amyloid fibers. Heparin, which triggers tau aggregation, is added to tau solution at time 0. (Fichou, et al., 2017)

Transmission electron microscopy (TEM) assay is a static imaging technology that could qualitatively and quantitatively monitor the fibrillization of tau at nanometer resolution. TEM assay enables the determination and isolation of abnormal forms of tau tangles.

Fig. 3 Electron micrographs of tau filaments. (Huseby & Kuret, 2016)

Aggregation Assay Service for Tau Isoforms

Tau isoforms are classified into 0N, 1N, 2N, 1R, 2R, 3R, and 4R tau isoforms according to the mRNA splicing mechanisms. The preferential aggregation of 3R and 4R tau isoforms may contribute to Alzheimer's disease. Creative Biolabs offers a range of tau aggregation assay services to understand which tau isoform aggregation is responsible for AD.

Understanding the tau gene transcription, tau RNA splicing, and tau protein translation mechanisms could shed light on the tau aggregation and further pathological and physiological processes related to AD or other tauopathies. The in vitro tau aggregation assays offered by Creative Biolabs provides researchers opportunities to discover the details of tau aggregation mechanisms and to develop tau aggregation-related therapeutics for AD. Please feel free to contact us for more information.

References

1. Shammas, S.; et al. A mechanistic model of tau amyloid aggregation based on direct observation of oligomers. Nature communications. 2015, 6(1): 1-10.
2. Fichou Y.; et al. Conformation-based assay of tau protein aggregation. Methods in cell biology. 2017, 141: 89-112.
3. Huseby, C. J.; Kuret, J. Analyzing Tau Aggregation with Electron Microscopy. Protein Amyloid Aggregation. 2016, 101–112.