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Cell Mol Life Sci. 2014 Jul;71(13):2561-76. doi: 10.1007/s00018-013-1515-x. Epub 2013 Nov 24.

OCIAD2 activates γ-secretase to enhance amyloid β production by interacting with nicastrin.

Author information

1
Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747, Korea.

Abstract

The gamma (γ)-secretase holoenzyme is composed of four core proteins and cleaves APP to generate amyloid beta (Aβ), a key molecule that causes major neurotoxicity during the early stage of Alzheimer's disease (AD). However, despite its important role in Aβ production, little is known about the regulation of γ-secretase. OCIAD2, a novel modulator of γ-secretase that stimulates Aβ production, and which was isolated from a genome-wide functional screen using cell-based assays and a cDNA library comprising 6,178 genes. Ectopic expression of OCIAD2 enhanced Aβ production, while reduction of OCIAD2 expression suppressed it. OCIAD2 expression facilitated the formation of an active γ-secretase complex and enhanced subcellular localization of the enzyme components to lipid rafts. OCIAD2 interacted with nicastrin to stimulate γ-secretase activity. OCIAD2 also increased the interaction of nicastrin with C99 and stimulated APP processing via γ-secretase activation, but did not affect Notch processing. In addition, a cell-permeable Tat-OCIAD2 peptide that interfered with the interaction of OCIAD2 with nicastrin interrupted the γ-secretase-mediated AICD production. Finally, OCIAD2 expression was significantly elevated in the brain of AD patients and PDAPP mice. This study identifies OCIAD2 as a selective activator of γ-secretase to increase Aβ generation.

PMID:
24270855
DOI:
10.1007/s00018-013-1515-x
[Indexed for MEDLINE]

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