Substrate determinants in the C99 juxtamembrane domains differentially affect γ-secretase cleavage specificity and modulator pharmacology.
J Neurochem
; 125(4): 610-9, 2013 May.
Article
em En
| MEDLINE
| ID: mdl-23253155
ABSTRACT
The molecular mechanisms governing γ-secretase cleavage specificity are not fully understood. Herein, we demonstrate that extending the transmembrane domain of the amyloid precursor protein-derived C99 substrate in proximity to the cytosolic face strongly influences γ-secretase cleavage specificity. Sequential insertion of leucines or replacement of membrane-anchoring lysines by leucines elevated the production of Aß42, whilst lowering production of Aß40. A single insertion or replacement was sufficient to produce this phenotype, suggesting that the helical length distal to the ε-site is a critical determinant of γ-secretase cleavage specificity. Replacing the lysine at the luminal membrane border (K28) with glutamic acid (K28E) increased Aß37 and reduced Aß42 production. Maintaining a positive charge with an arginine replacement, however, did not alter cleavage specificity. Using two potent and structurally distinct γ-secretase modulators (GSMs), we elucidated the contribution of K28 to the modulatory mechanism. Surprisingly, whilst lowering the potency of the non-steroidal anti-inflammatory drug-type GSM, the K28E mutation converted a heteroaryl-type GSM to an inverse GSM. This result implies the proximal lysine is critical for the GSM mechanism and pharmacology. This region is likely a major determinant for substrate binding and we speculate that modulation of substrate binding is the fundamental mechanism by which GSMs exert their action.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Precursor de Proteína beta-Amiloide
/
Secretases da Proteína Precursora do Amiloide
/
Doença de Alzheimer
Limite:
Humans
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article