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Van Acker ZP, Perdok A, Hellemans R, North K, Vorsters I, Cappel C, Dehairs J, Swinnen JV, Sannerud R, Bretou M, Damme M, Annaert W. Phospholipase D3 degrades mitochondrial DNA to regulate nucleotide signaling and APP metabolism. Nat Commun 2023; 14:2847. [PMID: 37225734 DOI: 10.1038/s41467-023-38501-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 05/04/2023] [Indexed: 05/26/2023] Open
Abstract
Phospholipase D3 (PLD3) polymorphisms are linked to late-onset Alzheimer's disease (LOAD). Being a lysosomal 5'-3' exonuclease, its neuronal substrates remained unknown as well as how a defective lysosomal nucleotide catabolism connects to AD-proteinopathy. We identified mitochondrial DNA (mtDNA) as a major physiological substrate and show its manifest build-up in lysosomes of PLD3-defective cells. mtDNA accretion creates a degradative (proteolytic) bottleneck that presents at the ultrastructural level as a marked abundance of multilamellar bodies, often containing mitochondrial remnants, which correlates with increased PINK1-dependent mitophagy. Lysosomal leakage of mtDNA to the cytosol activates cGAS-STING signaling that upregulates autophagy and induces amyloid precursor C-terminal fragment (APP-CTF) and cholesterol accumulation. STING inhibition largely normalizes APP-CTF levels, whereas an APP knockout in PLD3-deficient backgrounds lowers STING activation and normalizes cholesterol biosynthesis. Collectively, we demonstrate molecular cross-talks through feedforward loops between lysosomal nucleotide turnover, cGAS-STING and APP metabolism that, when dysregulated, result in neuronal endolysosomal demise as observed in LOAD.
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Affiliation(s)
- Zoë P Van Acker
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Anika Perdok
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Ruben Hellemans
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Katherine North
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Inge Vorsters
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Cedric Cappel
- Laboratory for Molecular Cell Biology and Transgenic Research, Institute of Biochemistry, Christian-Albrechts-University Kiel, Otto-Hahn-Platz 9, Kiel, Germany
| | - Jonas Dehairs
- Laboratory of Lipid Metabolism & Cancer, Department of Oncology, KU Leuven, B-3000, Leuven, Belgium
| | - Johannes V Swinnen
- Laboratory of Lipid Metabolism & Cancer, Department of Oncology, KU Leuven, B-3000, Leuven, Belgium
| | - Ragna Sannerud
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Marine Bretou
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium
| | - Markus Damme
- Laboratory for Molecular Cell Biology and Transgenic Research, Institute of Biochemistry, Christian-Albrechts-University Kiel, Otto-Hahn-Platz 9, Kiel, Germany
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB Center for Brain & Disease Research, Herestraat 49, box 602, Leuven, Belgium.
- Department of Neurosciences, KU Leuven, Herestraat 49, box 602, Leuven, Belgium.
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Van Acker ZP, Perdok A, Bretou M, Annaert W. The microglial lysosomal system in Alzheimer's disease: Guardian against proteinopathy. Ageing Res Rev 2021; 71:101444. [PMID: 34391945 DOI: 10.1016/j.arr.2021.101444] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/14/2021] [Accepted: 08/08/2021] [Indexed: 12/12/2022]
Abstract
Microglia, the brain-resident immune cells, play an essential role in the upkeep of brain homeostasis. They actively adapt into specific activation states based on cues from the microenvironment. One of these encompasses the activated response microglia (ARMs) phenotype. It arises along a healthy aging process and in a range of neurodegenerative diseases, including Alzheimer's disease (AD). As the phenotype is characterized by an increased lipid metabolism, phagocytosis rate, lysosomal protease content and secretion of neuroprotective agents, it leaves to reason that the phenotype is adapted in an attempt to restore homeostasis. This is important to the conundrum of inflammatory processes. Inflammation per se may not be deleterious; it is only when microglial reactions become chronic or the microglial subtype is made dysfunctional by (multiple) risk proteins with single-nucleotide polymorphisms that microglial involvement becomes deleterious instead of beneficial. Interestingly, the ARMs up- and downregulate many late-onset AD-associated risk factor genes, the products of which are particularly active in the endolysosomal system. Hence, in this review, we focus on how the endolysosomal system is placed at the crossroad of inflammation and microglial capacity to keep pace with degradation.
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