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Devkota S, Zhou R, Nagarajan V, Maesako M, Do H, Noorani A, Overmeyer C, Bhattarai S, Douglas JT, Saraf A, Miao Y, Ackley BD, Shi Y, Wolfe MS. Familial Alzheimer mutations stabilize synaptotoxic γ-secretase-substrate complexes. Cell Rep 2024; 43:113761. [PMID: 38349793 PMCID: PMC10941010 DOI: 10.1016/j.celrep.2024.113761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/19/2023] [Accepted: 01/24/2024] [Indexed: 02/15/2024] Open
Abstract
Mutations that cause familial Alzheimer's disease (FAD) are found in amyloid precursor protein (APP) and presenilin, the catalytic component of γ-secretase, that together produce amyloid β-peptide (Aβ). Nevertheless, whether Aβ is the primary disease driver remains controversial. We report here that FAD mutations disrupt initial proteolytic events in the multistep processing of APP substrate C99 by γ-secretase. Cryoelectron microscopy reveals that a substrate mimetic traps γ-secretase during the transition state, and this structure aligns with activated enzyme-substrate complex captured by molecular dynamics simulations. In silico simulations and in cellulo fluorescence microscopy support stabilization of enzyme-substrate complexes by FAD mutations. Neuronal expression of C99 and/or presenilin-1 in Caenorhabditis elegans leads to synaptic loss only with FAD-mutant transgenes. Designed mutations that stabilize the enzyme-substrate complex and block Aβ production likewise led to synaptic loss. Collectively, these findings implicate the stalled process-not the products-of γ-secretase cleavage of substrates in FAD pathogenesis.
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Affiliation(s)
- Sujan Devkota
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, USA
| | - Rui Zhou
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | | | - Masato Maesako
- Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Hung Do
- Center for Computational Biology, University of Kansas, Lawrence, KS, USA
| | - Arshad Noorani
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, USA
| | - Caitlin Overmeyer
- Graduate Program in Neurosciences, University of Kansas, Lawrence, KS, USA
| | - Sanjay Bhattarai
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, USA
| | - Justin T Douglas
- Nuclear Magnetic Resonance Core Lab, University of Kansas, Lawrence, KS, USA
| | - Anita Saraf
- Mass Spectrometry and Analytical Proteomic Laboratory, University of Kansas, Lawrence, KS, USA
| | - Yinglong Miao
- Center for Computational Biology, University of Kansas, Lawrence, KS, USA; Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
| | - Brian D Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
| | - Yigong Shi
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China; Westlake Laboratory of Life Science and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, and Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang Province, China
| | - Michael S Wolfe
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, USA; Graduate Program in Neurosciences, University of Kansas, Lawrence, KS, USA.
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Sfera A, Thomas KG, Andronescu CV, Jafri N, Sfera DO, Sasannia S, Zapata-Martín del Campo CM, Maldonado JC. Bromodomains in Human-Immunodeficiency Virus-Associated Neurocognitive Disorders: A Model of Ferroptosis-Induced Neurodegeneration. Front Neurosci 2022; 16:904816. [PMID: 35645713 PMCID: PMC9134113 DOI: 10.3389/fnins.2022.904816] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) comprise a group of illnesses marked by memory and behavioral dysfunction that can occur in up to 50% of HIV patients despite adequate treatment with combination antiretroviral drugs. Iron dyshomeostasis exacerbates HIV-1 infection and plays a major role in Alzheimer's disease pathogenesis. In addition, persons living with HIV demonstrate a high prevalence of neurodegenerative disorders, indicating that HAND provides a unique opportunity to study ferroptosis in these conditions. Both HIV and combination antiretroviral drugs increase the risk of ferroptosis by augmenting ferritin autophagy at the lysosomal level. As many viruses and their proteins exit host cells through lysosomal exocytosis, ferroptosis-driving molecules, iron, cathepsin B and calcium may be released from these organelles. Neurons and glial cells are highly susceptible to ferroptosis and neurodegeneration that engenders white and gray matter damage. Moreover, iron-activated microglia can engage in the aberrant elimination of viable neurons and synapses, further contributing to ferroptosis-induced neurodegeneration. In this mini review, we take a closer look at the role of iron in the pathogenesis of HAND and neurodegenerative disorders. In addition, we describe an epigenetic compensatory system, comprised of bromodomain-containing protein 4 (BRD4) and microRNA-29, that may counteract ferroptosis by activating cystine/glutamate antiporter, while lowering ferritin autophagy and iron regulatory protein-2. We also discuss potential interventions for lysosomal fitness, including ferroptosis blockers, lysosomal acidification, and cathepsin B inhibitors to achieve desirable therapeutic effects of ferroptosis-induced neurodegeneration.
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Affiliation(s)
- Adonis Sfera
- Patton State Hospital, San Bernardino, CA, United States
- Department of Psychiatry, University of California, Riverside, Riverside, CA, United States
| | | | | | - Nyla Jafri
- Patton State Hospital, San Bernardino, CA, United States
| | - Dan O. Sfera
- Patton State Hospital, San Bernardino, CA, United States
| | | | | | - Jose C. Maldonado
- Department of Medicine, The University of Texas Rio Grande Valley, Edinburg, TX, United States
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