Tauopathy-Associated Tau Fragment Ending at Amino Acid 224 Is Generated by Calpain-2 Cleavage
(2020) In Journal of Alzheimer's disease : JAD 74(4). p.1143-1156- Abstract
BACKGROUND: Tau aggregation in neurons and glial cells characterizes tauopathies as Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). Tau proteolysis has been proposed as a trigger for tau aggregation and tau fragments have been observed in brain and cerebrospinal fluid (CSF). Our group identified a major tau cleavage at amino acid (aa) 224 in CSF; N-terminal tau fragments ending at aa 224 (N-224) were significantly increased in AD and lacked correlation to total tau (t-tau) and phosphorylated tau (p-tau) in PSP and CBD.
OBJECTIVE: Previous studies have shown cleavage from calpain proteases at sites adjacent to aa 224. Our aim was to investigate if calpain-1 or -2 could be... (More)
BACKGROUND: Tau aggregation in neurons and glial cells characterizes tauopathies as Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). Tau proteolysis has been proposed as a trigger for tau aggregation and tau fragments have been observed in brain and cerebrospinal fluid (CSF). Our group identified a major tau cleavage at amino acid (aa) 224 in CSF; N-terminal tau fragments ending at aa 224 (N-224) were significantly increased in AD and lacked correlation to total tau (t-tau) and phosphorylated tau (p-tau) in PSP and CBD.
OBJECTIVE: Previous studies have shown cleavage from calpain proteases at sites adjacent to aa 224. Our aim was to investigate if calpain-1 or -2 could be responsible for cleavage at aa 224.
METHODS: Proteolytic activity of calpain-1, calpain-2, and brain protein extract was assessed on a custom tau peptide (aa 220-228), engineered with fluorescence resonance energy transfer (FRET) technology. Findings were confirmed with in-gel trypsination and mass spectrometry (MS) analysis of brain-derived bands with proteolytic activity on the FRET substrate. Finally, knock-down of the calpain-2 catalytic subunit gene (CAPN2) was performed in a neuroblastoma cell line (SH-SY5Y).
RESULTS: Calpain-2 and brain protein extract, but not calpain-1, showed proteolytic activity on the FRET substrate. MS analysis of active gel bands revealed presence of calpain-2 subunits, but not calpain-1. Calpain-2 depletion and chemical inhibition suppressed proteolysis of the FRET substrate. CAPN2 knock-down caused a 76.4% reduction of N-224 tau in the cell-conditioned media.
CONCLUSIONS: Further investigation of the calpain-2 pathway in the pathogenesis of tauopathies is encouraged.
(Less)
- author
- Cicognola, Claudia LU ; Satir, Tugce Munise ; Brinkmalm, Gunnar ; Matečko-Burmann, Irena ; Agholme, Lotta ; Bergström, Petra ; Becker, Bruno ; Zetterberg, Henrik LU ; Blennow, Kaj LU and Höglund, Kina
- publishing date
- 2020-03-02
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Alzheimer's disease : JAD
- volume
- 74
- issue
- 4
- pages
- 1143 - 1156
- publisher
- IOS Press
- external identifiers
-
- pmid:32144989
- scopus:85083895735
- ISSN
- 1387-2877
- DOI
- 10.3233/JAD-191130
- language
- English
- LU publication?
- no
- id
- 73a98769-3aff-494e-bb44-9e0957f0810a
- date added to LUP
- 2020-03-24 10:31:13
- date last changed
- 2024-10-02 22:55:47
@article{73a98769-3aff-494e-bb44-9e0957f0810a, abstract = {{<p>BACKGROUND: Tau aggregation in neurons and glial cells characterizes tauopathies as Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). Tau proteolysis has been proposed as a trigger for tau aggregation and tau fragments have been observed in brain and cerebrospinal fluid (CSF). Our group identified a major tau cleavage at amino acid (aa) 224 in CSF; N-terminal tau fragments ending at aa 224 (N-224) were significantly increased in AD and lacked correlation to total tau (t-tau) and phosphorylated tau (p-tau) in PSP and CBD.</p><p>OBJECTIVE: Previous studies have shown cleavage from calpain proteases at sites adjacent to aa 224. Our aim was to investigate if calpain-1 or -2 could be responsible for cleavage at aa 224.</p><p>METHODS: Proteolytic activity of calpain-1, calpain-2, and brain protein extract was assessed on a custom tau peptide (aa 220-228), engineered with fluorescence resonance energy transfer (FRET) technology. Findings were confirmed with in-gel trypsination and mass spectrometry (MS) analysis of brain-derived bands with proteolytic activity on the FRET substrate. Finally, knock-down of the calpain-2 catalytic subunit gene (CAPN2) was performed in a neuroblastoma cell line (SH-SY5Y).</p><p>RESULTS: Calpain-2 and brain protein extract, but not calpain-1, showed proteolytic activity on the FRET substrate. MS analysis of active gel bands revealed presence of calpain-2 subunits, but not calpain-1. Calpain-2 depletion and chemical inhibition suppressed proteolysis of the FRET substrate. CAPN2 knock-down caused a 76.4% reduction of N-224 tau in the cell-conditioned media.</p><p>CONCLUSIONS: Further investigation of the calpain-2 pathway in the pathogenesis of tauopathies is encouraged.</p>}}, author = {{Cicognola, Claudia and Satir, Tugce Munise and Brinkmalm, Gunnar and Matečko-Burmann, Irena and Agholme, Lotta and Bergström, Petra and Becker, Bruno and Zetterberg, Henrik and Blennow, Kaj and Höglund, Kina}}, issn = {{1387-2877}}, language = {{eng}}, month = {{03}}, number = {{4}}, pages = {{1143--1156}}, publisher = {{IOS Press}}, series = {{Journal of Alzheimer's disease : JAD}}, title = {{Tauopathy-Associated Tau Fragment Ending at Amino Acid 224 Is Generated by Calpain-2 Cleavage}}, url = {{http://dx.doi.org/10.3233/JAD-191130}}, doi = {{10.3233/JAD-191130}}, volume = {{74}}, year = {{2020}}, }