In situ seeding assay: A novel technique for direct tissue localization of bioactive tau

• Published in: Journal of neuropathology and experimental neurology 2024-10, Vol.83 (10), p.870-881
• Main Authors: Perbet, Romain, Mate de Gerando, Anastasie, Glynn, Calina, Donahue, Cameron, Gaona, Angelica, Taddei, Raquel N, Gomez-Isla, Teresa, Lathuiliere, Aurelien, Hyman, Bradley T
• Format: Article
• Language: English
• Subjects: Alzheimer Disease - metabolism; Alzheimer Disease - pathology; Alzheimer's disease; Biosensing Techniques - methods; Biosensors; Brain - metabolism; Brain - pathology; Humans; Neurofibrillary Tangles - metabolism; Neurofibrillary Tangles - pathology; tau Proteins - metabolism; Tauopathies - metabolism; Tauopathies - pathology
• ISSN: 0022-3069; 1554-6578; 1554-6578
• DOI: 10.1093/jnen/nlae059

Abstract Proteins exhibiting prion-like properties are implicated in tauopathies. The prion-like traits of tau influence disease progression and correlate with severity. Techniques to measure tau bioactivity such as RT-QuIC and biosensor cells lack spatial specificity. Therefore, we developed a histological probe aimed at detecting and localizing bioactive tau in situ. We first induced the recruitment of a tagged probe by bioactive Tau in human brain tissue slices using biosensor cell lysates containing a fluorescent probe. We then enhanced sensitivity and flexibility by designing a recombinant probe with a myc tag. The probe design aimed to replicate the recruitment process seen in prion-like mechanisms based on the cryo-EM structure of tau aggregates in Alzheimer disease (AD). Using this novel probe, we observed selective staining of misfolded tau in pre- and post-synaptic structures within neurofibrillary tangles and neurites, whether or not associated with neuritic plaques. The probe specifically targeted AD-associated bioactive tau and did not recognize bioactive tau from other neurodegenerative diseases. Electron microscopy and immunolabeling further confirmed the identification of fibrillar and non-fibrillar tau. Finally, we established a correlation between quantifying bioactive tau using this technique and gold standard biosensor cells. This technique presents a robust approach for detecting bioactive tau in AD tissues and has potential applications for deciphering mechanisms of tau propagation and degradation pathways.