PERSONAL DE APOYO
LLOVERA Ramiro Esteban
artículos
Título:
The catalytic domain of insulin-degrading enzyme forms a denaturant-resistant complex with amyloid beta peptide: implications for Alzheimer disease pathogenesis.
Autor/es:
LLOVERA RE, DE TULLIO M, ALONSO LG, LEISSRING MA, KAUFMAN SB, ROHER AE, DE PRAT GAY G, MORELLI L, CASTAÑO EM.
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Referencias:
Año: 2008 p. 17039 - 17048
ISSN:
0021-9258
Resumen:
Insulin-degrading enzyme (IDE) is central to the turnover of insulin
and degrades amyloid beta (Abeta) in the mammalian brain. Biochemical
and genetic data support the notion that IDE may play a role in late
onset Alzheimer disease (AD), and recent studies suggest an association
between AD and diabetes mellitus type 2. Here we show that a natively
folded recombinant IDE was capable of forming a stable complex with
Abeta that resisted dissociation after treatment with strong
denaturants. This interaction was also observed with rat brain IDE and
detected in an SDS-soluble fraction from AD cortical tissue. Abeta
sequence 17-27, known to be crucial in amyloid assembly, was sufficient
to form a stable complex with IDE. Monomeric as opposed to aggregated
Abeta was competent to associate irreversibly with IDE following a very
slow kinetics (t(1/2) approximately 45 min). Partial denaturation of
IDE as well as preincubation with a 10-fold molar excess of insulin
prevented complex formation, suggesting that the irreversible
interaction of Abeta takes place with at least part of the substrate
binding site of the protease. Limited proteolysis showed that Abeta
remained bound to a approximately 25-kDa N-terminal fragment of IDE in
an SDS-resistant manner. Mass spectrometry after in gel digestion of
the IDE .Abeta complex showed that peptides derived from the region
that includes the catalytic site of IDE were recovered with Abeta.
Taken together, these results are suggestive of an unprecedented
mechanism of conformation-dependent substrate binding that may perturb
Abeta clearance, insulin turnover, and promote AD pathogenesis.