Chem. 2005 Dec 23;280(51):41987-96. Epub
2005 Oct 19. Proc
Natl Acad Sci U S A. 2006 May 2;103(18):7130-5.
Epub 2006 Apr 25.
gamma-Secretase substrate selectivity can be modulated directly via interaction with a nucleotide-binding site.
Fraering PC, Ye W, LaVoie MJ, Ostaszewski BL, Selkoe DJ, Wolfe MS.
Center for Neurologic Diseases, Brigham & Women's Hospital and
gamma-Secretase is an unusual protease with an intramembrane catalytic site that cleaves many type I membrane proteins, including the amyloid beta-protein (Abeta) precursor (APP) and the Notch receptor. Genetic and biochemical studies have identified four membrane proteins as components of gamma-secretase: heterodimeric presenilin composed of its N- and C-terminal fragments, nicastrin, Aph-1, and Pen-2. Here we demonstrated that certain compounds, including protein kinase inhibitors and their derivatives, act directly on purified gamma-secretase to selectively block cleavage of APP- but not Notch-based substrates. Moreover, ATP activated the generation of the APP intracellular domain and Abeta, but not the generation of the Notch intracellular domain by the purified protease complex, and was a direct competitor of the APP-selective inhibitors, as were other nucleotides. In accord, purified gamma-secretase bound specifically to an ATP-linked resin. Finally, a photoactivable ATP analog specifically labeled presenilin 1-C-terminal fragments in purified gamma-secretase preparations; the labeling was blocked by ATP itself and APP-selective gamma-secretase inhibitors. We concluded that a nucleotide-binding site exists within gamma-secretase, and certain compounds that bind to this site can specifically modulate the generation of Abeta while sparing Notch. Drugs targeting the gamma-secretase nucleotide-binding site represent an attractive strategy for safely treating Alzheimer disease.
PMID: 16236717 [PubMed - indexed for MEDLINE]
Reversal of Alzheimer's-like pathology and behavior in human APP transgenic mice by mutation of Asp664.
Galvan V, Gorostiza OF, Banwait S, Ataie M, Logvinova AV, Sitaraman S, Carlson E, Sagi SA, Chevallier N, Jin K, Greenberg DA, Bredesen DE.
*Buck Institute for Age Research,
The deficits characteristic of Alzheimer's disease (AD) are believed to result, at least in part, from the neurotoxic effects of beta-amyloid peptides, a set of 39-43 amino acid fragments derived proteolytically from beta-amyloid precursor protein (APP). APP also is cleaved intracytoplasmically at Asp-664 to generate a second cytotoxic peptide, APP-C31, but whether this C-terminal processing of APP plays a role in the pathogenesis of AD is unknown. Therefore, we compared elements of the Alzheimer's phenotype in transgenic mice modeling AD with vs. without a functional Asp-664 caspase cleavage site. Surprisingly, whereas beta-amyloid production and plaque formation were unaltered, synaptic loss, astrogliosis, dentate gyral atrophy, increased neuronal precursor proliferation, and behavioral abnormalities were completely prevented by a mutation at Asp-664. These results suggest that Asp-664 plays a critical role in the generation of Alzheimer-related pathophysiological and behavioral changes in human APP transgenic mice, possibly as a cleavage site or via protein-protein interactions.
PMID: 16641106 [PubMed - in process]
J Biol Chem. 2005 Dec 23;280(51):41987-96. Epub 2005 Oct 19.
Proc Natl Acad Sci U S A. 2006 May 2;103(18):7130-5. Epub 2006 Apr 25.