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Gutta G, Mehta J, Kingston R, Xie J, Brenner E, Ma F, Herrup K. DNA Damage and Senescence in the Aging and Alzheimer's Disease Cortex Are Not Uniformly Distributed. Biomedicines 2024; 12:1327. [PMID: 38927534 PMCID: PMC11201767 DOI: 10.3390/biomedicines12061327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/26/2024] [Accepted: 05/29/2024] [Indexed: 06/28/2024] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative illness with a typical age of onset exceeding 65 years of age. The age dependency of the condition led us to track the appearance of DNA damage in the frontal cortex of individuals who died with a diagnosis of AD. The focus on DNA damage was motivated by evidence that increasing levels of irreparable DNA damage are a major driver of the aging process. The connection between aging and the loss of genomic integrity is compelling because DNA damage has also been identified as a possible cause of cellular senescence. The number of senescent cells has been reported to increase with age, and their senescence-associated secreted products are likely contributing factors to age-related illnesses. We tracked DNA damage with 53BP1 and cellular senescence with p16 immunostaining of human post-mortem brain samples. We found that DNA damage was significantly increased in the BA9 region of the AD cortex compared with the same region in unaffected controls (UCs). In the AD but not UC cases, the density of cells with DNA damage increased with distance from the pia mater up to approximately layer V and then decreased in deeper areas. This pattern of DNA damage was overlaid with the pattern of cellular senescence, which also increased with cortical depth. On a cell-by-cell basis, we found that the intensities of the two markers were tightly linked in the AD but not the UC brain. To test whether DNA damage was a causal factor in the emergence of the senescence program, we used etoposide treatment to damage the DNA of cultured mouse primary neurons. While DNA damage increased after treatment, after 24 h, no change in the expression of senescence-associated markers was observed. Our work suggests that DNA damage and cellular senescence are both increased in the AD brain and increasingly coupled. We propose that in vivo, the relationship between the two age-related processes is more complex than previously thought.
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Affiliation(s)
- Gnanesh Gutta
- School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (G.G.)
| | - Jay Mehta
- School of Pharmacy, University of Pittsburgh, Pittsburgh, PA 15260, USA;
| | - Rody Kingston
- School of Medicine, Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.K.); (K.H.)
| | - Jiaan Xie
- School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (G.G.)
| | - Eliana Brenner
- School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (G.G.)
| | - Fulin Ma
- School of Medicine, Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.K.); (K.H.)
| | - Karl Herrup
- School of Medicine, Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.K.); (K.H.)
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2
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Murphy MP, Buzinova VA, Johnson CE. The amyloid-β peptide: Guilty as charged? Biochim Biophys Acta Mol Basis Dis 2024; 1870:166945. [PMID: 37935338 PMCID: PMC10842071 DOI: 10.1016/j.bbadis.2023.166945] [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: 07/27/2023] [Revised: 10/25/2023] [Accepted: 10/31/2023] [Indexed: 11/09/2023]
Abstract
Recent years have seen both considerable progress and controversy in the Alzheimer's disease (AD) field. After decades of slow to negligible movement towards the development of disease modifying therapies, promising outcomes in recent clinical trials with several monoclonal antibodies targeting various forms of the amyloid-β (Aβ) peptide have at last opened a possible way forward. In fact, at this point multiple anti-Aβ therapeutics are close to receiving (or have already received) regulatory approval. Although these outcomes are not without some degree of divisiveness, the fact remains that targeting amyloid for removal has finally shown at least modest efficacy in slowing the otherwise relentless progression of the disease. Although the validation of the long standing amyloid cascade hypothesis would seem to be at hand, what remains is the puzzling issue of why - if Aβ indeed causes AD - does removing it from the brain not stop the disease entirely.
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Affiliation(s)
- M Paul Murphy
- Department of Molecular and Cellular Biochemistry and the Sanders-Brown Center on Aging University of Kentucky, 789 S. Limestone Street, Lexington, KY 40536, USA.
| | - Valeria A Buzinova
- Department of Molecular and Cellular Biochemistry and the Sanders-Brown Center on Aging University of Kentucky, 789 S. Limestone Street, Lexington, KY 40536, USA
| | - Carrie E Johnson
- Department of Molecular and Cellular Biochemistry and the Sanders-Brown Center on Aging University of Kentucky, 789 S. Limestone Street, Lexington, KY 40536, USA
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3
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Ramsden CE, Zamora D, Horowitz MS, Jahanipour J, Calzada E, Li X, Keyes GS, Murray HC, Curtis MA, Faull RM, Sedlock A, Maric D. ApoER2-Dab1 disruption as the origin of pTau-associated neurodegeneration in sporadic Alzheimer's disease. Acta Neuropathol Commun 2023; 11:197. [PMID: 38093390 PMCID: PMC10720169 DOI: 10.1186/s40478-023-01693-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/16/2023] [Indexed: 12/17/2023] Open
Abstract
In sporadic Alzheimer's disease (sAD) specific regions, layers and neurons accumulate hyperphosphorylated Tau (pTau) and degenerate early while others remain unaffected even in advanced disease. ApoER2-Dab1 signaling suppresses Tau phosphorylation as part of a four-arm pathway that regulates lipoprotein internalization and the integrity of actin, microtubules, and synapses; however, the role of this pathway in sAD pathogenesis is not fully understood. We previously showed that multiple ApoER2-Dab1 pathway components including ApoE, Reelin, ApoER2, Dab1, pP85αTyr607, pLIMK1Thr508, pTauSer202/Thr205 and pPSD95Thr19 accumulate together within entorhinal-hippocampal terminal zones in sAD, and proposed a unifying hypothesis wherein disruption of this pathway underlies multiple aspects of sAD pathogenesis. However, it is not yet known whether ApoER2-Dab1 disruption can help explain the origin(s) and early progression of pTau pathology in sAD. In the present study, we applied in situ hybridization and immunohistochemistry (IHC) to characterize ApoER2 expression and accumulation of ApoER2-Dab1 pathway components in five regions known to develop early pTau pathology in 64 rapidly autopsied cases spanning the clinicopathological spectrum of sAD. We found that (1) these selectively vulnerable neuron populations strongly express ApoER2; and (2) multiple ApoER2-Dab1 components representing all four arms of this pathway accumulate in abnormal neurons and neuritic plaques in mild cognitive impairment (MCI) and sAD cases and correlate with histological progression and cognitive deficits. Multiplex-IHC revealed that Dab1, pP85αTyr607, pLIMK1Thr508, pTauSer202/Thr205 and pPSD95Thr19 accumulate together within many of the same ApoER2-expressing neurons and in the immediate vicinity of ApoE/ApoJ-enriched extracellular plaques. Collective findings reveal that pTau is only one of many ApoER2-Dab1 pathway components that accumulate in multiple neuroanatomical sites in the earliest stages of sAD and provide support for the concept that ApoER2-Dab1 disruption drives pTau-associated neurodegeneration in human sAD.
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Affiliation(s)
- Christopher E Ramsden
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH (NIA/NIH), 251 Bayview Blvd., Baltimore, MD, 21224, USA.
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, 20892, USA.
| | - Daisy Zamora
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH (NIA/NIH), 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Mark S Horowitz
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH (NIA/NIH), 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Jahandar Jahanipour
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Elizabeth Calzada
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH (NIA/NIH), 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Xiufeng Li
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH (NIA/NIH), 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Gregory S Keyes
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH (NIA/NIH), 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Helen C Murray
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Richard M Faull
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Andrea Sedlock
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
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Acharyya D, Norman V. Amyloid Precursor Protein Can Cause Changes in Neuronal Firing Rates via Axon Initial Segment. J Neurosci 2023; 43:8088-8089. [PMID: 38030402 PMCID: PMC10697388 DOI: 10.1523/jneurosci.0842-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 09/01/2023] [Accepted: 09/05/2023] [Indexed: 12/01/2023] Open
Affiliation(s)
- Debalina Acharyya
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37916
| | - Victoria Norman
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37916
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Quintela-López T, Lezmy J. Homeostatic plasticity of axonal excitable sites in Alzheimer's disease. Front Neurosci 2023; 17:1277251. [PMID: 37937068 PMCID: PMC10626477 DOI: 10.3389/fnins.2023.1277251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 10/06/2023] [Indexed: 11/09/2023] Open
Affiliation(s)
| | - Jonathan Lezmy
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
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Dan L, Zhang Z. Alzheimer's disease: an axonal injury disease? Front Aging Neurosci 2023; 15:1264448. [PMID: 37927337 PMCID: PMC10620718 DOI: 10.3389/fnagi.2023.1264448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 09/14/2023] [Indexed: 11/07/2023] Open
Abstract
Alzheimer's disease (AD) is the primary cause of dementia and is anticipated to impose a substantial economic burden in the future. Over a significant period, the widely accepted amyloid cascade hypothesis has guided research efforts, and the recent FDA approval of an anti- amyloid-beta (Aβ) protofibrils antibody, believed to decelerate AD progression, has further solidified its significance. However, the excessive emphasis placed on the amyloid cascade hypothesis has overshadowed the physiological nature of Aβ and tau proteins within axons. Axons, specialized neuronal structures, sustain damage during the early stages of AD, exerting a pivotal influence on disease progression. In this review, we present a comprehensive summary of the relationship between axonal damage and AD pathology, amalgamating the physiological roles of Aβ and tau proteins, along with the impact of AD risk genes such as APOE and TREM2. Furthermore, we underscore the exceptional significance of axonal damage in the context of AD.
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Affiliation(s)
| | - Zhaohui Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
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7
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Dunot J, Ribera A, Pousinha PA, Marie H. Spatiotemporal insights of APP function. Curr Opin Neurobiol 2023; 82:102754. [PMID: 37542943 DOI: 10.1016/j.conb.2023.102754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/29/2023] [Accepted: 07/07/2023] [Indexed: 08/07/2023]
Abstract
The amyloid-β precursor protein (APP) is a ubiquitous protein with a strong genetic link to Alzheimer's disease. Although the protein was identified more than forty years ago, its physiological function is still unclear. In recent years, advances in technology have allowed researchers to tackle APP functions in greater depth. In this review, we discuss the latest research pertaining to APP functions from development to aging. We also address the different roles that APP could play in specific types of cells of the central and peripheral nervous system and in other organs of the body. We argue that, until we fully identify the functions of APP in space and time, we will be missing important pieces of the puzzle to solve its pathological implication in Alzheimer's disease and beyond.
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Affiliation(s)
- Jade Dunot
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France. https://twitter.com/DunotJade
| | - Aurore Ribera
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France. https://twitter.com/aurore_et_al_
| | - Paula A Pousinha
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France.
| | - Hélène Marie
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France.
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8
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Ramsden CE, Zamora D, Horowitz M, Jahanipour J, Keyes G, Li X, Murray HC, Curtis MA, Faull RM, Sedlock A, Maric D. ApoER2-Dab1 disruption as the origin of pTau-related neurodegeneration in sporadic Alzheimer's disease. RESEARCH SQUARE 2023:rs.3.rs-2968020. [PMID: 37461602 PMCID: PMC10350181 DOI: 10.21203/rs.3.rs-2968020/v1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
BACKGROUND Sporadic Alzheimer's disease (sAD) is not a global brain disease. Specific regions, layers and neurons degenerate early while others remain untouched even in advanced disease. The prevailing model used to explain this selective neurodegeneration-prion-like Tau spread-has key limitations and is not easily integrated with other defining sAD features. Instead, we propose that in humans Tau hyperphosphorylation occurs locally via disruption in ApoER2-Dab1 signaling and thus the presence of ApoER2 in neuronal membranes confers vulnerability to degeneration. Further, we propose that disruption of the Reelin/ApoE/ApoJ-ApoER2-Dab1-P85α-LIMK1-Tau-PSD95 (RAAAD-P-LTP) pathway induces deficits in memory and cognition by impeding neuronal lipoprotein internalization and destabilizing actin, microtubules, and synapses. This new model is based in part on our recent finding that ApoER2-Dab1 disruption is evident in entorhinal-hippocampal terminal zones in sAD. Here, we hypothesized that neurons that degenerate in the earliest stages of sAD (1) strongly express ApoER2 and (2) show evidence of ApoER2-Dab1 disruption through co-accumulation of multiple RAAAD-P-LTP components. METHODS We applied in situ hybridization and immunohistochemistry to characterize ApoER2 expression and accumulation of RAAAD-P-LTP components in five regions that are prone to early pTau pathology in 64 rapidly autopsied cases spanning the clinicopathological spectrum of sAD. RESULTS We found that: (1) selectively vulnerable neuron populations strongly express ApoER2; (2) numerous RAAAD-P-LTP pathway components accumulate in neuritic plaques and abnormal neurons; and (3) RAAAD-P-LTP components were higher in MCI and sAD cases and correlated with histological progression and cognitive deficits. Multiplex-IHC revealed that Dab1, pP85αTyr607, pLIMK1Thr508, pTau and pPSD95Thr19 accumulated together within dystrophic dendrites and soma of ApoER2-expressing neurons in the vicinity of ApoE/ApoJ-enriched extracellular plaques. These observations provide evidence for molecular derangements that can be traced back to ApoER2-Dab1 disruption, in each of the sampled regions, layers, and neuron populations that are prone to early pTau pathology. CONCLUSION Findings support the RAAAD-P-LTP hypothesis, a unifying model that implicates dendritic ApoER2-Dab1 disruption as the major driver of both pTau accumulation and neurodegeneration in sAD. This model provides a new conceptual framework to explain why specific neurons degenerate and identifies RAAAD-P-LTP pathway components as potential mechanism-based biomarkers and therapeutic targets for sAD.
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Affiliation(s)
| | - Daisy Zamora
- National Institute on Aging Laboratory of Clinical Investigation
| | - Mark Horowitz
- National Institute on Aging Intramural Research Program
| | | | - Gregory Keyes
- National Institute on Aging Laboratory of Clinical Investigation
| | - Xiufeng Li
- National Institute on Aging Laboratory of Clinical Investigation
| | - Helen C Murray
- The University of Auckland Faculty of Medical and Health Sciences
| | - Maurice A Curtis
- The University of Auckland Faculty of Medical and Health Sciences
| | - Richard M Faull
- The University of Auckland Faculty of Medical and Health Sciences
| | - Andrea Sedlock
- NINDS: National Institute of Neurological Disorders and Stroke
| | - Dragan Maric
- NINDS: National Institute of Neurological Disorders and Stroke
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9
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Ramsden CE, Zamora D, Horowitz MS, Jahanipour J, Keyes GS, Li X, Murray HC, Curtis MA, Faull RM, Sedlock A, Maric D. ApoER2-Dab1 disruption as the origin of pTau-related neurodegeneration in sporadic Alzheimer's disease. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.05.19.23290250. [PMID: 37333406 PMCID: PMC10274982 DOI: 10.1101/2023.05.19.23290250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
BACKGROUND Sporadic Alzheimer's disease (sAD) is not a global brain disease. Specific regions, layers and neurons degenerate early while others remain untouched even in advanced disease. The prevailing model used to explain this selective neurodegeneration-prion-like Tau spread-has key limitations and is not easily integrated with other defining sAD features. Instead, we propose that in humans Tau hyperphosphorylation occurs locally via disruption in ApoER2-Dab1 signaling and thus the presence of ApoER2 in neuronal membranes confers vulnerability to degeneration. Further, we propose that disruption of the Reelin/ApoE/ApoJ-ApoER2-Dab1-P85α-LIMK1-Tau-PSD95 (RAAAD-P-LTP) pathway induces deficits in memory and cognition by impeding neuronal lipoprotein internalization and destabilizing actin, microtubules, and synapses. This new model is based in part on our recent finding that ApoER2-Dab1 disruption is evident in entorhinal-hippocampal terminal zones in sAD. Here, we hypothesized that neurons that degenerate in the earliest stages of sAD (1) strongly express ApoER2 and (2) show evidence of ApoER2-Dab1 disruption through co-accumulation of multiple RAAAD-P-LTP components. METHODS We applied in situ hybridization and immunohistochemistry to characterize ApoER2 expression and accumulation of RAAAD-P-LTP components in five regions that are prone to early pTau pathology in 64 rapidly autopsied cases spanning the clinicopathological spectrum of sAD. RESULTS We found that: (1) selectively vulnerable neuron populations strongly express ApoER2; (2) numerous RAAAD-P-LTP pathway components accumulate in neuritic plaques and abnormal neurons; and (3) RAAAD-P-LTP components were higher in MCI and sAD cases and correlated with histological progression and cognitive deficits. Multiplex-IHC revealed that Dab1, pP85αTyr607, pLIMK1Thr508, pTau and pPSD95Thr19 accumulated together within dystrophic dendrites and soma of ApoER2-expressing neurons in the vicinity of ApoE/ApoJ-enriched extracellular plaques. These observations provide evidence for molecular derangements that can be traced back to ApoER2-Dab1 disruption, in each of the sampled regions, layers, and neuron populations that are prone to early pTau pathology. CONCLUSION Findings support the RAAAD-P-LTP hypothesis, a unifying model that implicates dendritic ApoER2-Dab1 disruption as the major driver of both pTau accumulation and neurodegeneration in sAD. This model provides a new conceptual framework to explain why specific neurons degenerate and identifies RAAAD-P-LTP pathway components as potential mechanism-based biomarkers and therapeutic targets for sAD.
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Affiliation(s)
- Christopher E. Ramsden
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH 251 Bayview Blvd., Baltimore, MD, 21224, USA
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, 20892, USA
| | - Daisy Zamora
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH 251 Bayview Blvd., Baltimore, MD, 21224, USA
- Department of Physical Medicine and Rehabilitation, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Mark S. Horowitz
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Jahandar Jahanipour
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Gregory S. Keyes
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Xiufeng Li
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, NIH 251 Bayview Blvd., Baltimore, MD, 21224, USA
| | - Helen C. Murray
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Maurice A. Curtis
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Richard M. Faull
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Andrea Sedlock
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892, USA
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Garrido JJ. Contribution of Axon Initial Segment Structure and Channels to Brain Pathology. Cells 2023; 12:cells12081210. [PMID: 37190119 DOI: 10.3390/cells12081210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 04/17/2023] [Accepted: 04/20/2023] [Indexed: 05/17/2023] Open
Abstract
Brain channelopathies are a group of neurological disorders that result from genetic mutations affecting ion channels in the brain. Ion channels are specialized proteins that play a crucial role in the electrical activity of nerve cells by controlling the flow of ions such as sodium, potassium, and calcium. When these channels are not functioning properly, they can cause a wide range of neurological symptoms such as seizures, movement disorders, and cognitive impairment. In this context, the axon initial segment (AIS) is the site of action potential initiation in most neurons. This region is characterized by a high density of voltage-gated sodium channels (VGSCs), which are responsible for the rapid depolarization that occurs when the neuron is stimulated. The AIS is also enriched in other ion channels, such as potassium channels, that play a role in shaping the action potential waveform and determining the firing frequency of the neuron. In addition to ion channels, the AIS contains a complex cytoskeletal structure that helps to anchor the channels in place and regulate their function. Therefore, alterations in this complex structure of ion channels, scaffold proteins, and specialized cytoskeleton may also cause brain channelopathies not necessarily associated with ion channel mutations. This review will focus on how the AISs structure, plasticity, and composition alterations may generate changes in action potentials and neuronal dysfunction leading to brain diseases. AIS function alterations may be the consequence of voltage-gated ion channel mutations, but also may be due to ligand-activated channels and receptors and AIS structural and membrane proteins that support the function of voltage-gated ion channels.
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Affiliation(s)
- Juan José Garrido
- Instituto Cajal, CSIC, 28002 Madrid, Spain
- Alzheimer's Disease and Other Degenerative Dementias, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), 28002 Madrid, Spain
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