title: Inhibitors of γ-secretase stabilize the complex and differentially affect processing of amyloid precursor protein and other substrates.
abstract: γ-Secretase inhibitors (GSIs) are drugs used in research to inhibit production of Aβ and in clinical trials to treat Alzheimer's disease (AD). They inhibit proteolytic activities of γ-secretase noncompetitively by unknown mechanisms. Here, we used cortical neuronal cultures expressing endogenous levels of enzymes and substrates to study the effects of GSIs on the structure and function of γ-secretase. We show that GSIs stabilize the interactions between the C-terminal fragment of presenilin (PS-CTF), the central component of the γ-secretase complex, and its partners the APH-1/nicastrin and PS1-NTF/PEN-2 subcomplexes. This stabilization dose-dependently correlates with inhibition of N-cadherin cleavage, a process limited by enzyme availability. In contrast, production of amyloid precursor protein (APP) intracellular domain (AICD) is insensitive to low concentrations of GSIs and is limited by substrate availability. Interestingly, APP is processed by both PS1- and PS2-containing γ-secretase complexes, while N-cadherin and ephrinB1 are processed only by PS1-containing complexes. Paradoxically, low concentrations of GSIs specifically increased the levels of Aβ without affecting its catabolism, indicating increased Aβ production. Our data reveal a mechanism of γ-secretase inhibition by GSIs and provide evidence that distinct γ-secretase complexes process specific substrates. Furthermore, our observations have implications for GSIs as therapeutics because processing of functionally important substrates may be inhibited at lower concentrations than Aβ.
authors: Department of Psychiatry, Mt. Sinai School of Medicine, New York University, New York, NY 10029, USA.
authors: Gael
authors: G
authors: Barthet
authors: Junichi
authors: J
authors: Shioi
authors: Zhiping
authors: Z
authors: Shao
authors: Yimin
authors: Y
authors: Ren
authors: Anastasios
authors: A
authors: Georgakopoulos
authors: Nikolaos K
authors: NK
authors: Robakis
references: Science. 2001 Dec 7;294(5549):2179-81
references: 11679632
references: Proc Natl Acad Sci U S A. 2003 Oct 28;100(22):13075-80
references: 14566063
references: J Biol Chem. 2008 Aug 22;283(34):22992-3003
references: 18574238
references: J Biol Chem. 2002 May 24;277(21):19236-40
references: 11943765
references: Clin Neuropharmacol. 2007 Nov-Dec;30(6):317-25
references: 18090456
references: Biochem Biophys Res Commun. 2006 Feb 10;340(2):668-74
references: 16376853
references: Genes Brain Behav. 2005 Apr;4(3):134-46
references: 15810902
references: J Biol Chem. 2003 Sep 26;278(39):37213-22
references: 12857757
references: J Biol Chem. 2002 Aug 2;277(31):28135-42
references: 12032140
references: Cell. 2003 Sep 5;114(5):635-45
references: 13678586
references: J Biol Chem. 2002 Aug 30;277(35):31499-505
references: 12072428
references: J Biol Chem. 2006 May 26;281(21):14670-6
references: 16569643
references: Biol Psychiatry. 2010 Nov 15;68(10):876-8
references: 21035622
references: J Biol Chem. 2003 Aug 1;278(31):28968-75
references: 12719412
references: EMBO J. 2006 Mar 22;25(6):1242-52
references: 16511561
references: Neuron. 2010 Sep 9;67(5):769-80
references: 20826309
references: J Biol Chem. 2007 Jun 1;282(22):16155-63
references: 17428795
references: J Pharmacol Exp Ther. 2009 Nov;331(2):598-608
references: 19671883
references: J Biol Chem. 1997 Nov 7;272(45):28415-22
references: 9353300
references: Nature. 1999 Apr 8;398(6727):518-22
references: 10206645
references: J Biol Chem. 2009 Jan 23;284(4):1954-61
references: 19008223
references: Clin Neuropharmacol. 2005 May-Jun;28(3):126-32
references: 15965311
references: Nature. 2010 Sep 2;467(7311):95-8
references: 20811458
references: J Cell Sci. 2003 Mar 15;116(Pt 6):1127-36
references: 12584255
references: J Biol Chem. 2004 Aug 27;279(35):36519-29
references: 15220354
references: J Neurochem. 2006 Feb;96(4):1182-8
references: 16417575
references: J Neurochem. 2001 Jan;76(1):173-81
references: 11145990
references: Exp Cell Res. 2008 Aug 1;314(13):2419-33
references: 18559276
references: J Biol Chem. 2008 Dec 12;283(50):34677-86
references: 18801744
references: Proc Natl Acad Sci U S A. 2010 Dec 14;107(50):21435-40
references: 21115843
references: Proc Natl Acad Sci U S A. 2002 Mar 5;99(5):2720-5
references: 11867728
references: J Biol Chem. 2004 Oct 1;279(40):41340-5
references: 15286082
references: J Pharmacol Exp Ther. 2006 Nov;319(2):924-33
references: 16920992
references: J Mol Biol. 1965 May;12:88-118
references: 14343300