1
|
Specific Mutations in Aph1 Cause γ-Secretase Activation. Int J Mol Sci 2022; 23:ijms23010507. [PMID: 35008932 PMCID: PMC8745412 DOI: 10.3390/ijms23010507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 01/25/2023] Open
Abstract
Amyloid beta peptides (Aβs) are generated from amyloid precursor protein (APP) through multiple cleavage steps mediated by γ-secretase, including endoproteolysis and carboxypeptidase-like trimming. The generation of neurotoxic Aβ42/43 species is enhanced by familial Alzheimer's disease (FAD) mutations within the catalytic subunit of γ-secretase, presenilin 1 (PS1). FAD mutations of PS1 cause partial loss-of-function and decrease the cleavage activity. Activating mutations, which have the opposite effect of FAD mutations, are important for studying Aβ production. Aph1 is a regulatory subunit of γ-secretase; it is presumed to function as a scaffold of the complex. In this study, we identified Aph1 mutations that are active in the absence of nicastrin (NCT) using a yeast γ-secretase assay. We analyzed these Aph1 mutations in the presence of NCT; we found that the L30F/T164A mutation is activating. When introduced in mouse embryonic fibroblasts, the mutation enhanced cleavage. The Aph1 mutants produced more short and long Aβs than did the wild-type Aph1, without an apparent modulatory function. The mutants did not change the amount of γ-secretase complex, suggesting that L30F/T164A enhances catalytic activity. Our results provide insights into the regulatory function of Aph1 in γ-secretase activity.
Collapse
|
2
|
Hu C, Xu J, Zeng L, Li T, Cui MZ, Xu X. Pen-2 and Presenilin are Sufficient to Catalyze Notch Processing. J Alzheimers Dis 2018; 56:1263-1269. [PMID: 28234257 DOI: 10.3233/jad-161094] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Presenilin-1 (PS1) or presenilin-2 (PS2), nicastrin (NCT), anterior pharynx-defective 1 (Aph-1), and presenilin enhancer-2 (Pen-2) have been considered the minimal essential subunits required to form an active γ-secretase complex. Besides PS, which has been widely believed to function as the catalytic subunit of the complex, the functional roles of the other subunits in the γ-secretase complex remain debatable. In the current study, we set out to determine the role of Pen-2 in γ-secretase activity. To this end, using knockout cells in combination with siRNA and immunoprecipitation approaches, our results revealed that Pen-2 together with presenilin are sufficient to form a functionally active enzyme to process Notch. Specifically, our data demonstrated that Pen-2 plays a crucial role in substrate binding, a mechanism by which Pen-2 contributes directly to the catalytic mechanism of γ-secretase activity. Our data also suggested that there may be different requirements for components to process AβPP and Notch. This information would be important for therapeutic strategy aimed at inhibition or modulation of γ-secretase activity.
Collapse
Affiliation(s)
- Chen Hu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| | - Junjie Xu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.,Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Jilin Medical University, Jilin, China
| | - Linlin Zeng
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.,School of Life Sciences, Jilin University, Changchun, China
| | - Ting Li
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.,Department of Cell Biology, Tianjin Medical University, Tianjin, China
| | - Mei-Zhen Cui
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| | - Xuemin Xu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| |
Collapse
|
3
|
Hu C, Zeng L, Li T, Meyer MA, Cui MZ, Xu X. Nicastrin is required for amyloid precursor protein (APP) but not Notch processing, while anterior pharynx-defective 1 is dispensable for processing of both APP and Notch. J Neurochem 2016; 136:1246-1258. [PMID: 26717550 DOI: 10.1111/jnc.13518] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/20/2015] [Accepted: 12/22/2015] [Indexed: 11/27/2022]
Abstract
The γ-secretase complex is composed of at least four components: presenilin 1 or presenilin-2, nicastrin (NCT), anterior pharynx-defective 1 (Aph-1), and presenilin enhancer 2. In this study, using knockout cell lines, our data demonstrated that knockout of NCT, as well as knockout of presenilin enhancer 2, completely blocked γ-secretase-catalyzed processing of C-terminal fragment (CTF)α and CTFβ, the C-terminal fragments of β-amyloid precursor protein (APP) produced by α-secretase and β-secretase cleavages, respectively. Interestingly, in Aph-1-knockout cells, CTFα and CTFβ were still processed by γ-secretase, indicating Aph-1 is dispensable for APP processing. Furthermore, our results indicate that Aph-1 as well as NCT is not absolutely required for Notch processing, suggesting that NCT is differentially required for APP and Notch processing. In addition, our data revealed that components of the γ-secretase complex are also important for proteasome- and lysosome-dependent degradation of APP and that endogenous APP is mostly degraded by lysosome while exogenous APP is mainly degraded by proteasome. There are unanswered questions regarding the roles of each component of the γ-secretase complex in amyloid precursor protein (APP) and Notch processing. The most relevant, novel finding of this study is that nicastrin (NCT) is required for APP but not Notch processing, while Aph-1 is not essential for processing of both APP and Notch, suggesting NCT as a therapeutic target to restrict Aβ formation without impairing Notch signaling.
Collapse
Affiliation(s)
- Chen Hu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
| | - Linlin Zeng
- School of Life Sciences, Jilin University, Changchun, China
| | - Ting Li
- Department of Cell Biology, Tianjin Medical University, Tianjin, China
| | | | - Mei-Zhen Cui
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
| | - Xuemin Xu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
| |
Collapse
|
4
|
Kanatsu K, Morohashi Y, Suzuki M, Kuroda H, Watanabe T, Tomita T, Iwatsubo T. Decreased CALM expression reduces Aβ42 to total Aβ ratio through clathrin-mediated endocytosis of γ-secretase. Nat Commun 2014; 5:3386. [PMID: 24577224 DOI: 10.1038/ncomms4386] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 02/05/2014] [Indexed: 01/08/2023] Open
Abstract
A body of evidence suggests that aberrant metabolism of amyloid-β peptide (Aβ) underlies the aetiology of Alzheimer disease (AD). Recently, a single-nucleotide polymorphism in phosphatidylinositol binding clathrin assembly protein (PICALM/CALM) gene, which encodes a protein implicated in the clathrin-mediated endocytosis, was identified as a genetic protective factor for AD, although its mechanistic details have little been explored. Here we show that loss of CALM leads to the selective decrease in the production ratio of the pathogenic Aβ species, Aβ42. Active form of γ-secretase is constitutively endocytosed via the clathrin-mediated pathway in a CALM dependent manner. Alteration in the rate of clathrin-mediated endocytosis of γ-secretase causes a shift in its steady-state localization, which consequently impacts on the production ratio of Aβ42. Our study identifies CALM as an endogenous modulator of γ-secretase activity by regulating its endocytosis and also as an excellent target for Aβ42-lowering AD therapeutics.
Collapse
Affiliation(s)
- Kunihiko Kanatsu
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2]
| | - Yuichi Morohashi
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 113-0033, Japan [3]
| | - Mai Suzuki
- Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Hiromasa Kuroda
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Toshio Watanabe
- Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Taisuke Tomita
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 113-0033, Japan
| | - Takeshi Iwatsubo
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 113-0033, Japan [3] Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| |
Collapse
|
5
|
De Strooper B, Iwatsubo T, Wolfe MS. Presenilins and γ-secretase: structure, function, and role in Alzheimer Disease. Cold Spring Harb Perspect Med 2013; 2:a006304. [PMID: 22315713 DOI: 10.1101/cshperspect.a006304] [Citation(s) in RCA: 308] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Presenilins were first discovered as sites of missense mutations responsible for early-onset Alzheimer disease (AD). The encoded multipass membrane proteins were subsequently found to be the catalytic components of γ-secretases, membrane-embedded aspartyl protease complexes responsible for generating the carboxyl terminus of the amyloid β-protein (Aβ) from the amyloid protein precursor (APP). The protease complex also cleaves a variety of other type I integral membrane proteins, most notably the Notch receptor, signaling from which is involved in many cell differentiation events. Although γ-secretase is a top target for developing disease-modifying AD therapeutics, interference with Notch signaling should be avoided. Compounds that alter Aβ production by γ-secretase without affecting Notch proteolysis and signaling have been identified and are currently at various stages in the drug development pipeline.
Collapse
Affiliation(s)
- Bart De Strooper
- Center for Human Genetics, Leuven Institute for Neurodegenerative Diseases, KULeuven, 3000 Leuven, Belgium; Department of Molecular and Developmental Genetics, VIB, 3000, Leuven, Belgium
| | | | | |
Collapse
|
6
|
Structure of a presenilin family intramembrane aspartate protease. Nature 2012; 493:56-61. [PMID: 23254940 DOI: 10.1038/nature11801] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 11/16/2012] [Indexed: 12/22/2022]
Abstract
Presenilin and signal peptide peptidase (SPP) are intramembrane aspartyl proteases that regulate important biological functions in eukaryotes. Mechanistic understanding of presenilin and SPP has been hampered by lack of relevant structural information. Here we report the crystal structure of a presenilin/SPP homologue (PSH) from the archaeon Methanoculleus marisnigri JR1. The protease, comprising nine transmembrane segments (TMs), adopts a previously unreported protein fold. The amino-terminal domain, consisting of TM1-6, forms a horseshoe-shaped structure, surrounding TM7-9 of the carboxy-terminal domain. The two catalytic aspartate residues are located on the cytoplasmic side of TM6 and TM7, spatially close to each other and approximately 8 Å into the lipid membrane surface. Water molecules gain constant access to the catalytic aspartates through a large cavity between the amino- and carboxy-terminal domains. Structural analysis reveals insights into the presenilin/SPP family of intramembrane proteases.
Collapse
|
7
|
Sanjo N, Katayama T, Hasegawa H, Jin H, Duthie M, Mount HTJ, Mizusawa H, St George-Hyslop P, Fraser PE. Localization and trafficking of endogenous anterior pharynx-defective 1, a component of Alzheimer's disease related gamma-secretase. Neurosci Lett 2010; 483:53-6. [PMID: 20674680 DOI: 10.1016/j.neulet.2010.07.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/20/2010] [Accepted: 07/23/2010] [Indexed: 10/19/2022]
Abstract
Anterior pharynx-defective 1 (Aph-1) is a multi-spanning membrane protein and an integral component of the high molecular weight gamma-secretase complex that also contains presenilin, nicastrin, and Pen-2. In order to clarify the existence of an endogenous fragment of Aph-1 and dissect the localization and processing of endogenous Aph-1 proteins, we examined cell lines and primary cell cultures with our own carboxyl terminal-specific antibodies for Aph-1aL. Fractionation and immunofluorescence studies indicated that the endogenous full-length Aph-1aL isoform localizes primarily to the endoplasmic reticulum as well as Golgi intermediate compartment, but small amount of it was detected at Golgi apparatus where most of its carboxyl terminal domain fragment existed. In primary neuronal and glial cultures, Aph-1aL was present in the neurites and glial cell processes. Endogenous Aph-1a and its proteolytic fragment have unique properties for cleavage control that may have implications for gamma-secretase regulation and intracellular distribution.
Collapse
Affiliation(s)
- Nobuo Sanjo
- Centre for Research in Neurodegenerative Diseases, University of Toronto, 6 Queen's Park Crescent West, Toronto, Ontario M5S 3H2, Canada.
| | | | | | | | | | | | | | | | | |
Collapse
|