Mechanism of intramembrane cleavage of alcadeins by γ-secretase.
PLoS One
; 8(4): e62431, 2013.
Article
in En
| MEDLINE
| ID: mdl-23658629
ABSTRACT
BACKGROUND:
Alcadein proteins (Alcs; Alcα, Alcßand Alcγ) are predominantly expressed in neurons, as is Alzheimer's ß-amyloid (Aß) precursor protein (APP). Both Alcs and APP are cleaved by primary α- or ß-secretase to generate membrane-associated C-terminal fragments (CTFs). Alc CTFs are further cleaved by γ-secretase to secrete p3-Alc peptide along with the release of intracellular domain fragment (Alc ICD) from the membrane. In the case of APP, APP CTFß is initially cleaved at the ε-site to release the intracellular domain fragment (AICD) and consequently the γ-site is determined, by which Aß generates. The initial ε-site is thought to define the final γ-site position, which determines whether Aß40/43 or Aß42 is generated. However, initial intracellular ε-cleavage sites of Alc CTF to generate Alc ICD and the molecular mechanism that final γ-site position is determined remains unclear in Alcs.METHODOLOGY:
Using HEK293 cells expressing Alcs plus presenilin 1 (PS1, a catalytic unit of γ-secretase) and the membrane fractions of these cells, the generation of p3-Alc possessing C-terminal γ-cleavage site and Alc ICD possessing N-terminal ε-cleavage site were analysed with MALDI-TOF/MS. We determined the initial ε-site position of all Alcα, Alcß and Alcγ, and analyzed the relationship between the initially determined ε-site position and the final γ-cleavage position.CONCLUSIONS:
The initial ε-site position does not always determine the final γ-cleavage position in Alcs, which differed from APP. No additional γ-cleavage sites are generated from artificial/non-physiological positions of ε-cleavage for Alcs, while the artificial ε-cleavage positions can influence in selection of physiological γ-site positions. Because alteration of γ-secretase activity is thought to be a pathogenesis of sporadic Alzheimer's disease, Alcs are useful and sensitive substrate to detect the altered cleavage of substrates by γ-secretase, which may be induced by malfunction of γ-secretase itself or changes of membrane environment for enzymatic reaction.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Peptide Fragments
/
Calcium-Binding Proteins
/
Cell Membrane
/
Amyloid Precursor Protein Secretases
/
Presenilin-1
/
Membrane Proteins
Limits:
Humans
Language:
En
Journal:
PLoS One
Journal subject:
CIENCIA
/
MEDICINA
Year:
2013
Document type:
Article
Affiliation country:
Japan