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Bretou M, Sannerud R, Escamilla-Ayala A, Leroy T, Vrancx C, Van Acker ZP, Perdok A, Vermeire W, Vorsters I, Van Keymolen S, Maxson M, Pavie B, Wierda K, Eskelinen EL, Annaert W. Accumulation of APP C-terminal fragments causes endolysosomal dysfunction through the dysregulation of late endosome to lysosome-ER contact sites. Dev Cell 2024:S1534-5807(24)00199-0. [PMID: 38626765 DOI: 10.1016/j.devcel.2024.03.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/02/2023] [Accepted: 03/20/2024] [Indexed: 04/18/2024]
Abstract
Neuronal endosomal and lysosomal abnormalities are among the early changes observed in Alzheimer's disease (AD) before plaques appear. However, it is unclear whether distinct endolysosomal defects are temporally organized and how altered γ-secretase function or amyloid precursor protein (APP) metabolism contribute to these changes. Inhibiting γ-secretase chronically, in mouse embryonic fibroblast and hippocampal neurons, led to a gradual endolysosomal collapse initiated by decreased lysosomal calcium and increased cholesterol, causing downstream defects in endosomal recycling and maturation. This endolysosomal demise is γ-secretase dependent, requires membrane-tethered APP cytoplasmic domains, and is rescued by APP depletion. APP C-terminal fragments (CTFs) localized to late endosome/lysosome-endoplasmic reticulum contacts; an excess of APP-CTFs herein reduced lysosomal Ca2+ refilling from the endoplasmic reticulum, promoting cholesterol accretion. Tonic regulation by APP-CTFs provides a mechanistic explanation for their cellular toxicity: failure to timely degrade APP-CTFs sustains downstream signaling, instigating lysosomal dyshomeostasis, as observed in prodromal AD. This is the opposite of substrates such as Notch, which require intramembrane proteolysis to initiate signaling.
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Affiliation(s)
- Marine Bretou
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Ragna Sannerud
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | | | - Tom Leroy
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Céline Vrancx
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Zoë P Van Acker
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Anika Perdok
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Wendy Vermeire
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Inge Vorsters
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Sophie Van Keymolen
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Michelle Maxson
- Cell Biology Program, The Hospital for Sick Children, Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Benjamin Pavie
- VIB-BioImaging Core, VIB-Center for Brain and Disease Research, Leuven, Belgium
| | - Keimpe Wierda
- Electrophysiology Expertise Unit, VIB-Center for Brain and Disease Research, Leuven, Belgium
| | | | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium.
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De Strooper B, Karran E. New precision medicine avenues to the prevention of Alzheimer's disease from insights into the structure and function of γ-secretases. EMBO J 2024; 43:887-903. [PMID: 38396302 PMCID: PMC10943082 DOI: 10.1038/s44318-024-00057-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 01/20/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Two phase-III clinical trials with anti-amyloid peptide antibodies have met their primary goal, i.e. slowing of Alzheimer's disease (AD) progression. However, antibody therapy may not be the optimal therapeutic modality for AD prevention, as we will discuss in the context of the earlier small molecules described as "γ-secretase modulators" (GSM). We review here the structure, function, and pathobiology of γ-secretases, with a focus on how mutations in presenilin genes result in early-onset AD. Significant progress has been made in generating compounds that act in a manner opposite to pathogenic presenilin mutations: they stabilize the proteinase-substrate complex, thereby increasing the processivity of substrate cleavage and altering the size spectrum of Aβ peptides produced. We propose the term "γ-secretase allosteric stabilizers" (GSAS) to distinguish these compounds from the rather heterogenous class of GSM. The GSAS represent, in theory, a precision medicine approach to the prevention of amyloid deposition, as they specifically target a discrete aspect in a complex cell biological signalling mechanism that initiates the pathological processes leading to Alzheimer's disease.
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Affiliation(s)
- Bart De Strooper
- Dementia Research Institute, Institute of Neurology, University College London, at the Francis Crick Institute, London, NW1 AT, UK.
- Laboratory for the Research of Neurodegenerative Diseases, VIB Center for Brain & Disease Research, and Leuven Brain Institute, KU Leuven, Leuven, 3000, Belgium.
| | - Eric Karran
- Cambridge Research Center, AbbVie, Inc., Cambridge, MA, USA
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Serneels L, Bammens L, Zwijsen A, Tolia A, Chávez-Gutiérrez L, De Strooper B. Functional and topological analysis of PSENEN, the fourth subunit of the γ-secretase complex. J Biol Chem 2024; 300:105533. [PMID: 38072061 PMCID: PMC10790097 DOI: 10.1016/j.jbc.2023.105533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/20/2023] [Accepted: 11/26/2023] [Indexed: 01/01/2024] Open
Abstract
The γ-secretase complexes are intramembrane cleaving proteases involved in the generation of the Aβ peptides in Alzheimer's disease. The complex consists of four subunits, with Presenilin harboring the catalytic site. Here, we study the role of the smallest subunit, PSENEN or Presenilin enhancer 2, encoded by the gene Psenen, in vivo and in vitro. We find a profound Notch deficiency phenotype in Psenen-/- embryos confirming the essential role of PSENEN in the γ-secretase complex. We used Psenen-/- fibroblasts to explore the structure-function of PSENEN by the scanning cysteine accessibility method. Glycine 22 and proline 27, which border the membrane domains 1 and 2 of PSENEN, are involved in complex formation and stabilization of γ-secretase. The hairpin structured hydrophobic membrane domains 1 and 2 are exposed to a water-containing cavity in the complex, while transmembrane domain 3 is not water exposed. We finally demonstrate the essential role of PSENEN for the cleavage activity of the complex. PSENEN is more than a structural component of the γ-secretase complex and might contribute to the catalytic mechanism of the enzyme.
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Affiliation(s)
- Lutgarde Serneels
- Laboratory for the Research of Neurodegenerative Diseases, VIB Center for Brain & Disease Research, VIB, Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Leen Bammens
- Laboratory for the Research of Neurodegenerative Diseases, VIB Center for Brain & Disease Research, VIB, Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - An Zwijsen
- Laboratory of Developmental Signaling, Center for Human Genetics, KU Leuven, Leuven, Belgium
| | - Alexandra Tolia
- Laboratory for the Research of Neurodegenerative Diseases, VIB Center for Brain & Disease Research, VIB, Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Lucía Chávez-Gutiérrez
- Laboratory for the Research of Neurodegenerative Diseases, VIB Center for Brain & Disease Research, VIB, Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Bart De Strooper
- Laboratory for the Research of Neurodegenerative Diseases, VIB Center for Brain & Disease Research, VIB, Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium.
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Vrijsen S, Vrancx C, Del Vecchio M, Swinnen JV, Agostinis P, Winderickx J, Vangheluwe P, Annaert W. Inter-organellar Communication in Parkinson's and Alzheimer's Disease: Looking Beyond Endoplasmic Reticulum-Mitochondria Contact Sites. Front Neurosci 2022; 16:900338. [PMID: 35801175 PMCID: PMC9253489 DOI: 10.3389/fnins.2022.900338] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/05/2022] [Indexed: 01/13/2023] Open
Abstract
Neurodegenerative diseases (NDs) are generally considered proteinopathies but whereas this may initiate disease in familial cases, onset in sporadic diseases may originate from a gradually disrupted organellar homeostasis. Herein, endolysosomal abnormalities, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and altered lipid metabolism are commonly observed in early preclinical stages of major NDs, including Parkinson's disease (PD) and Alzheimer's disease (AD). Among the multitude of underlying defective molecular mechanisms that have been suggested in the past decades, dysregulation of inter-organellar communication through the so-called membrane contact sites (MCSs) is becoming increasingly apparent. Although MCSs exist between almost every other type of subcellular organelle, to date, most focus has been put on defective communication between the ER and mitochondria in NDs, given these compartments are critical in neuronal survival. Contributions of other MCSs, notably those with endolysosomes and lipid droplets are emerging, supported as well by genetic studies, identifying genes functionally involved in lysosomal homeostasis. In this review, we summarize the molecular identity of the organelle interactome in yeast and mammalian cells, and critically evaluate the evidence supporting the contribution of disturbed MCSs to the general disrupted inter-organellar homeostasis in NDs, taking PD and AD as major examples.
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Affiliation(s)
- Stephanie Vrijsen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
| | - Céline Vrancx
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Mara Del Vecchio
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Johannes V. Swinnen
- Laboratory of Lipid Metabolism and Cancer, Department of Oncology, Leuven Cancer Institute (LKI), KU Leuven, Leuven, Belgium
- Johannes V. Swinnen
| | - Patrizia Agostinis
- Laboratory of Cell Death Research and Therapy, VIB-Center for Cancer Research, KU Leuven, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
- Patrizia Agostinis
| | - Joris Winderickx
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
- Joris Winderickx
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
- Peter Vangheluwe
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- *Correspondence: Wim Annaert
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Chatterjee S, Choi AJ, Frankel G. A systematic review of Sec24 cargo interactome. Traffic 2021; 22:412-424. [PMID: 34533884 DOI: 10.1111/tra.12817] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/27/2021] [Accepted: 09/13/2021] [Indexed: 01/10/2023]
Abstract
Endoplasmic reticulum (ER)-to-Golgi trafficking is an essential and highly conserved cellular process. The coat protein complex-II (COPII) arm of the trafficking machinery incorporates a wide array of cargo proteins into vesicles through direct or indirect interactions with Sec24, the principal subunit of the COPII coat. Approximately one-third of all mammalian proteins rely on the COPII-mediated secretory pathway for membrane insertion or secretion. There are four mammalian Sec24 paralogs and three yeast Sec24 paralogs with emerging evidence of paralog-specific cargo interaction motifs. Furthermore, individual paralogs also differ in their affinity for a subset of sorting motifs present on cargo proteins. As with many aspects of protein trafficking, we lack a systematic and thorough understanding of the interaction of Sec24 with cargoes. This systematic review focuses on the current knowledge of cargo binding to both yeast and mammalian Sec24 paralogs and their ER export motifs. The analyses show that Sec24 paralog specificity of cargo (and cargo receptors) range from exclusive paralog dependence or preference to partial redundancy. We also discuss how the Sec24 secretion system is hijacked by viral (eg, VSV-G, Hepatitis B envelope protein) and bacterial (eg, the enteropathogenic Escherichia coli type III secretion system effector NleA/EspI) pathogens.
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Affiliation(s)
- Sharanya Chatterjee
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Ana Jeemin Choi
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Gad Frankel
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
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