N368-Tau fragments generated by legumain are detected only in trace amount in the insoluble Tau aggregates isolated from AD brain
| Autor: | Laura Gasparini, Khader Awwad, Stefan Barghorn, Thomas R. Jahn, Annika Doell, Yulia Mordashova, Kerstin Schlegel, David Holzinger, Roland G. Heym, Michael Schulz, Corinna Klein |
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| Rok vydání: | 2019 |
| Předmět: |
Male
Tau protein Mice Transgenic tau Proteins Cleavage (embryo) Fibril Legumain lcsh:RC346-429 Pathology and Forensic Medicine Mice Protein Aggregates Cellular and Molecular Neuroscience chemistry.chemical_compound mental disorders medicine Animals Humans Amino Acid Sequence lcsh:Neurology. Diseases of the nervous system Aged Tau protease Aged 80 and over Mice Knockout biology Chemistry Research Brain Insoluble Tau Human brain Middle Aged medicine.disease Molecular biology Cysteine Endopeptidases medicine.anatomical_structure Tau truncation Knockout mouse biology.protein Female Thioflavin Neurology (clinical) Alzheimer disease Alzheimer's disease |
| Zdroj: | Acta Neuropathologica Communications, Vol 7, Iss 1, Pp 1-15 (2019) Acta Neuropathologica Communications |
| ISSN: | 2051-5960 |
| Popis: | Intraneuronal insoluble inclusions made of Tau protein are neuropathological hallmarks of Alzheimer Disease (AD). Cleavage of Tau by legumain (LGMN) has been proposed to be crucial for aggregation of Tau into fibrils. However, it remains unclear if LGMN-cleaved Tau fragments accumulate in AD Tau inclusions. Using an in vitro enzymatic assay and non-targeted mass spectrometry, we identified four putative LGMN cleavage sites at Tau residues N167-, N255-, N296- and N368. Cleavage at N368 generates variously sized N368-Tau fragments that are aggregation prone in the Thioflavin T assay in vitro. N368-cleaved Tau is not detected in the brain of legumain knockout mice, indicating that LGMN is required for Tau cleavage in the mouse brain in vivo. Using a targeted mass spectrometry method in combination with tissue fractionation and biochemical analysis, we investigated whether N368-cleaved Tau is differentially produced and aggregated in brain of AD patients and control subjects. In brain soluble extracts, despite reduced uncleaved Tau in AD, levels of N368-cleaved Tau are comparable in AD and control hippocampus, suggesting that LGMN-mediated cleavage of Tau is not altered in AD. Consistently, levels of activated, cleaved LGMN are also similar in AD and control brain extracts. To assess the potential accumulation of N368-cleaved Tau in insoluble Tau aggregates, we analyzed sarkosyl-insoluble extracts from AD and control hippocampus. Both N368-cleaved Tau and uncleaved Tau were significantly increased in AD as a consequence of pathological Tau inclusions accumulation. However, the amount of N368-cleaved Tau represented only a very minor component ( Our data indicate that LGMN physiologically cleaves Tau in the mouse and human brain generating N368-cleaved Tau fragments, which remain largely soluble and are present only in low proportion in Tau insoluble aggregates compared to uncleaved Tau. This suggests that LGMN-cleaved Tau has limited role in the progressive accumulation of Tau inclusions in AD. |
| Databáze: | OpenAIRE |
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