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Niño SA, Chi-Ahumada E, Carrizales L, Estrada-Sánchez AM, Gonzalez-Billault C, Zarazúa S, Concha L, Jiménez-Capdeville ME. Life-long arsenic exposure damages the microstructure of the rat hippocampus. Brain Res 2022; 1775:147742. [PMID: 34848172 DOI: 10.1016/j.brainres.2021.147742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 09/18/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/19/2022]
Abstract
Epidemiological studies demonstrate that arsenic exposure is associated with cognitive dysfunction. Experimental arsenic exposure models showed learning and memory deficits and molecular changes resembling the functional and pathologic neurodegeneration features. The present work focuses on hippocampal pathological changes in Wistar rats induced by continuous arsenic exposure from in utero up to 12 months of age, evaluated by magnetic resonance imaging along with immunohistochemistry. Diffusion-weighted images revealed age-related lower fractional anisotropy and higher radial-axial and mean diffusivity at 6 and 12 months, indicating that arsenic exposure leads to hippocampal demyelination. These structural alterations were paralleled by immunohistochemical changes that showed a significant loss of myelin basic protein in CA1 and CA3 regions accompanied by increased glial fibrillary acidic protein expression at all time-points studied. Concomitantly, arsenic exposure induced an altered morphology of astrocytes at all studied ages, whereas increased synaptogenesis was only observed at two months of age. These results suggest that environmental arsenic exposure is linked to impaired hippocampal connectivity and perhaps early glial senescence, which together might resemble a premature aging phenomenon leading to cognitive deficits.
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Affiliation(s)
- Sandra A Niño
- Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí, Mexico; Geroscience Center for Brain Health and Metabolism (GERO), Santiago de Chile, Chile
| | - Erika Chi-Ahumada
- Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí, Mexico
| | - Leticia Carrizales
- Coordination for Innovation and Application of Science and Technology (CIACYT), Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí, Mexico
| | - Ana María Estrada-Sánchez
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, San Luis Potosi, Mexico
| | - Christian Gonzalez-Billault
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago de Chile, Chile; Geroscience Center for Brain Health and Metabolism (GERO), Santiago de Chile, Chile
| | - Sergio Zarazúa
- Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí, Mexico
| | - Luis Concha
- Instituto de Neurobiología, UNAM Campus Juriquilla, Querétaro, Querétaro, Mexico
| | - María E Jiménez-Capdeville
- Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí, Mexico.
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Gil L, Niño SA, Guerrero C, Jiménez-Capdeville ME. Phospho-Tau and Chromatin Landscapes in Early and Late Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms221910283. [PMID: 34638632 PMCID: PMC8509045 DOI: 10.3390/ijms221910283] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/17/2021] [Accepted: 09/18/2021] [Indexed: 12/25/2022] Open
Abstract
Cellular identity is determined through complex patterns of gene expression. Chromatin, the dynamic structure containing genetic information, is regulated through epigenetic modulators, mainly by the histone code. One of the main challenges for the cell is maintaining functionality and identity, despite the accumulation of DNA damage throughout the aging process. Replicative cells can remain in a senescent state or develop a malign cancer phenotype. In contrast, post-mitotic cells such as pyramidal neurons maintain extraordinary functionality despite advanced age, but they lose their identity. This review focuses on tau, a protein that protects DNA, organizes chromatin, and plays a crucial role in genomic stability. In contrast, tau cytosolic aggregates are considered hallmarks of Alzheimer´s disease (AD) and other neurodegenerative disorders called tauopathies. Here, we explain AD as a phenomenon of chromatin dysregulation directly involving the epigenetic histone code and a progressive destabilization of the tau–chromatin interaction, leading to the consequent dysregulation of gene expression. Although this destabilization could be lethal for post-mitotic neurons, tau protein mediates profound cellular transformations that allow for their temporal survival.
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Affiliation(s)
- Laura Gil
- Departamento de Genética, Escuela de Medicina, Universidad “Alfonso X el Sabio”, 28691 Madrid, Spain;
| | - Sandra A. Niño
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma, de San Luis Potosí 78210, Mexico;
| | - Carmen Guerrero
- Banco de Cerebros (Biobanco), Hospital Universitario Fundación Alcorcón, Alcorcón, 28922 Madrid, Spain;
| | - María E. Jiménez-Capdeville
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma, de San Luis Potosí 78210, Mexico;
- Correspondence: ; Tel.: +52-444-826-2366
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Niño SA, Vázquez-Hernández N, Arevalo-Villalobos J, Chi-Ahumada E, Martín-Amaya-Barajas FL, Díaz-Cintra S, Martel-Gallegos G, González-Burgos I, Jiménez-Capdeville ME. Cortical Synaptic Reorganization Under Chronic Arsenic Exposure. Neurotox Res 2021; 39:1970-1980. [PMID: 34533753 DOI: 10.1007/s12640-021-00409-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 03/29/2021] [Revised: 08/02/2021] [Accepted: 08/30/2021] [Indexed: 12/24/2022]
Abstract
There is solid epidemiological evidence that arsenic exposure leads to cognitive impairment, while experimental work supports the hypothesis that it also contributes to neurodegeneration. Energy deficit, oxidative stress, demyelination, and defective neurotransmission are demonstrated arsenic effects, but it remains unclear whether synaptic structure is also affected. Employing both a triple-transgenic Alzheimer's disease model and Wistar rats, the cortical microstructure and synapses were analyzed under chronic arsenic exposure. Male animals were studied at 2 and 4 months of age, after exposure to 3 ppm sodium arsenite in drinking water during gestation, lactation, and postnatal development. Through nuclear magnetic resonance, diffusion-weighted images were acquired and anisotropy (integrity; FA) and apparent diffusion coefficient (dispersion degree; ADC) metrics were derived. Postsynaptic density protein and synaptophysin were analyzed by means of immunoblot and immunohistochemistry, while dendritic spine density and morphology of cortical pyramidal neurons were quantified after Golgi staining. A structural reorganization of the cortex was evidenced through high-ADC and low-FA values in the exposed group. Similar changes in synaptic protein levels in the 2 models suggest a decreased synaptic connectivity at 4 months of age. An abnormal dendritic arborization was observed at 4 months of age, after increased spine density at 2 months. These findings demonstrate alterations of cortical synaptic connectivity and microstructure associated to arsenic exposure appearing in young rodents and adults, and these subtle and non-adaptive plastic changes in dendritic spines and in synaptic markers may further progress to the degeneration observed at older ages.
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Affiliation(s)
- Sandra A Niño
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Nallely Vázquez-Hernández
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS. Guadalajara, Jalisco, Mexico
| | - Jaime Arevalo-Villalobos
- Facultad de Agronomía y Veterinaria, Universidad Autónoma de San Luis Potosí, Soledad de Graciano Sánchez, San Luis Potosí, Mexico
| | - Erika Chi-Ahumada
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | | | - Sofía Díaz-Cintra
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Mexico
| | - Guadalupe Martel-Gallegos
- Laboratorio de Biomedicina, Unidad Académica Multidisciplinaria Zona Media, Universidad Autónoma de San Luis Potosí, Rio Verde, San Luis Potosí, Mexico
| | - Ignacio González-Burgos
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS. Guadalajara, Jalisco, Mexico
| | - María E Jiménez-Capdeville
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico.
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Gil L, Niño SA, Capdeville G, Jiménez-Capdeville ME. Aging and Alzheimer's disease connection: Nuclear Tau and lamin A. Neurosci Lett 2021; 749:135741. [PMID: 33610669 DOI: 10.1016/j.neulet.2021.135741] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [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: 08/25/2020] [Revised: 01/12/2021] [Accepted: 02/11/2021] [Indexed: 12/24/2022]
Abstract
Age-related pathologies like Alzheimer`s disease (AD) imply cellular responses directed towards repairing DNA damage. Postmitotic neurons show progressive accumulation of oxidized DNA during decades of brain aging, which is especially remarkable in AD brains. The characteristic cytoskeletal pathology of AD neurons is brought about by the progressive changes that neurons undergo throughout aging, and their irreversible nuclear transformation initiates the disease. This review focusses on critical molecular events leading to the loss of plasticity that underlies cognitive deficits in AD. During healthy neuronal aging, nuclear Tau participates in the regulation of the structure and function of the chromatin. The aberrant cell cycle reentry initiated for DNA repair triggers a cascade of events leading to the dysfunctional AD neuron, whereby Tau protein exits the nucleus leading to chromatin disorganization. Lamin A, which is not typically expressed in neurons, appears at the transformation from senile to AD neurons and contributes to halting the consequences of cell cycle reentry and nuclear Tau exit, allowing the survival of the neuron. Nevertheless, this irreversible nuclear transformation alters the nucleic acid and protein synthesis machinery as well as the nuclear lamina and cytoskeleton structures, leading to neurofibrillary tangles formation and final neurodegeneration.
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Affiliation(s)
- Laura Gil
- Departamento de Genética, Escuela de Medicina, Universidad "Alfonso X el Sabio", Madrid, Spain
| | - Sandra A Niño
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Mexico
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Niño SA, Chi-Ahumada E, Ortíz J, Zarazua S, Concha L, Jiménez-Capdeville ME. Demyelination associated with chronic arsenic exposure in Wistar rats. Toxicol Appl Pharmacol 2020; 393:114955. [PMID: 32171569 DOI: 10.1016/j.taap.2020.114955] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 01/01/2020] [Revised: 02/18/2020] [Accepted: 03/10/2020] [Indexed: 02/01/2023]
Abstract
Inorganic arsenic is among the major contaminants of groundwater in the world. Worldwide population-based studies demonstrate that chronic arsenic exposure is associated with poor cognitive performance among children and adults, while research in animal models confirms learning and memory deficits after arsenic exposure. The aim of this study was to investigate the long-term effects of environmentally relevant arsenic exposure in the myelination process of the prefrontal cortex (PFC) and corpus callosum (CC). A longitudinal study with repeated follow-up assessments was performed in male Wistar rats exposed to 3 ppm sodium arsenite in drinking water. Animals received the treatment from gestation until 2, 4, 6, or 12 months of postnatal age. The levels of myelin basic protein (MBP) were evaluated by immunohistochemistry/histology and immunoblotting from the PFC and CC. As plausible alterations associated with demyelination, we considered mitochondrial mass (VDAC) and two axonal damage markers: amyloid precursor protein (APP) level and phosphorylated neurofilaments. To analyze the microstructure of the CC in vivo, we acquired diffusion-weighted images at the same ages, from which we derived metrics using the tensor model. Significantly decreased levels of MBP were found in both regions together with significant increases of mitochondrial mass and slight axonal damage at 12 months in the PFC. Ultrastructural imaging demonstrated arsenic-associated decreases of white matter volume, water diffusion anisotropy, and increases in radial diffusivity. This study indicates that arsenic exposure is associated with a significant and persistent negative impact on microstructural features of white matter tracts.
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Affiliation(s)
- Sandra A Niño
- Laboratorio de Neurotoxicología, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava 6, C.P 78210 San Luis Potosí, Mexico
| | - Erika Chi-Ahumada
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Av. Venustiano Carranza 2405, C.P 78210 San Luis Potosí, Mexico
| | - Juan Ortíz
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Querétaro, Querétaro C.P 76230, Mexico
| | - Sergio Zarazua
- Laboratorio de Neurotoxicología, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava 6, C.P 78210 San Luis Potosí, Mexico
| | - Luis Concha
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Querétaro, Querétaro C.P 76230, Mexico
| | - Maria E Jiménez-Capdeville
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Av. Venustiano Carranza 2405, C.P 78210 San Luis Potosí, Mexico.
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Gil L, Niño SA, Chi-Ahumada E, Rodríguez-Leyva I, Guerrero C, Rebolledo AB, Arias JA, Jiménez-Capdeville ME. Perinuclear Lamin A and Nucleoplasmic Lamin B2 Characterize Two Types of Hippocampal Neurons through Alzheimer's Disease Progression. Int J Mol Sci 2020; 21:E1841. [PMID: 32155994 PMCID: PMC7084765 DOI: 10.3390/ijms21051841] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 02/28/2020] [Accepted: 03/03/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Recent reports point to a nuclear origin of Alzheimer's disease (AD). Aged postmitotic neurons try to repair their damaged DNA by entering the cell cycle. This aberrant cell cycle re-entry involves chromatin modifications where nuclear Tau and the nuclear lamin are involved. The purpose of this work was to elucidate their participation in the nuclear pathological transformation of neurons at early AD. METHODOLOGY The study was performed in hippocampal paraffin embedded sections of adult, senile, and AD brains at I-VI Braak stages. We analyzed phospho-Tau, lamins A, B1, B2, and C, nucleophosmin (B23) and the epigenetic marker H4K20me3 by immunohistochemistry. RESULTS Two neuronal populations were found across AD stages, one is characterized by a significant increase of Lamin A expression, reinforced perinuclear Lamin B2, elevated expression of H4K20me3 and nuclear Tau loss, while neurons with nucleoplasmic Lamin B2 constitute a second population. CONCLUSIONS The abnormal cell cycle reentry in early AD implies a fundamental neuronal transformation. This implies the reorganization of the nucleo-cytoskeleton through the expression of the highly regulated Lamin A, heterochromatin repression and building of toxic neuronal tangles. This work demonstrates that nuclear Tau and lamin modifications in hippocampal neurons are crucial events in age-related neurodegeneration.
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Affiliation(s)
- Laura Gil
- Departamento de Genética, Escuela de Medicina, Universidad “Alfonso X el Sabio”, 28691 Madrid, Spain; (L.G.)
| | - Sandra A. Niño
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | - Erika Chi-Ahumada
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | | | - Carmen Guerrero
- Banco de cerebros (Biobanco), Hospital Universitario Fundación Alcorcón, Alcorcón, 28922 Madrid, Spain
| | - Ana Belén Rebolledo
- Banco de cerebros (Biobanco), Hospital Universitario Fundación Alcorcón, Alcorcón, 28922 Madrid, Spain
| | - José A. Arias
- Departamento de Genética, Escuela de Medicina, Universidad “Alfonso X el Sabio”, 28691 Madrid, Spain; (L.G.)
| | - María E. Jiménez-Capdeville
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
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