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Paiva I, Seguin J, Grgurina I, Singh AK, Cosquer B, Plassard D, Tzeplaeff L, Le Gras S, Cotellessa L, Decraene C, Gambi J, Alcala-Vida R, Eswaramoorthy M, Buée L, Cassel JC, Giacobini P, Blum D, Merienne K, Kundu TK, Boutillier AL. Dysregulated expression of cholesterol biosynthetic genes in Alzheimer's disease alters epigenomic signatures of hippocampal neurons. Neurobiol Dis 2024; 198:106538. [PMID: 38789057 DOI: 10.1016/j.nbd.2024.106538] [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: 12/29/2023] [Revised: 05/18/2024] [Accepted: 05/20/2024] [Indexed: 05/26/2024] Open
Abstract
Aging is the main risk factor of cognitive neurodegenerative diseases such as Alzheimer's disease, with epigenome alterations as a contributing factor. Here, we compared transcriptomic/epigenomic changes in the hippocampus, modified by aging and by tauopathy, an AD-related feature. We show that the cholesterol biosynthesis pathway is severely impaired in hippocampal neurons of tauopathic but not of aged mice pointing to vulnerability of these neurons in the disease. At the epigenomic level, histone hyperacetylation was observed at neuronal enhancers associated with glutamatergic regulations only in the tauopathy. Lastly, a treatment of tau mice with the CSP-TTK21 epi-drug that restored expression of key cholesterol biosynthesis genes counteracted hyperacetylation at neuronal enhancers and restored object memory. As acetyl-CoA is the primary substrate of both pathways, these data suggest that the rate of the cholesterol biosynthesis in hippocampal neurons may trigger epigenetic-driven changes, that may compromise the functions of hippocampal neurons in pathological conditions.
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Affiliation(s)
- Isabel Paiva
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France.
| | - Jonathan Seguin
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Iris Grgurina
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Akash Kumar Singh
- Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
| | - Brigitte Cosquer
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Damien Plassard
- University of Strasbourg, CNRS UMR7104, Inserm U1258 - GenomEast Platform - IGBMC - Institut de Génétique et de Biologie Moléculaire et Cellulaire, F-67404 Illkirch, France
| | - Laura Tzeplaeff
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Stephanie Le Gras
- University of Strasbourg, CNRS UMR7104, Inserm U1258 - GenomEast Platform - IGBMC - Institut de Génétique et de Biologie Moléculaire et Cellulaire, F-67404 Illkirch, France
| | - Ludovica Cotellessa
- University of Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Postnatal Brain, Lille Neuroscience & Cognition, UMR-S1172, FHU 1000 Days for Health, 59000 Lille, France
| | - Charles Decraene
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Johanne Gambi
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Rafael Alcala-Vida
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Muthusamy Eswaramoorthy
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Luc Buée
- University of Lille, Inserm, CHU Lille, UMR-S1172 LilNCog - Lille Neuroscience & Cognition, Lille, France; Alzheimer and Tauopathies, LabEx DISTALZ, France
| | - Jean-Christophe Cassel
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Paolo Giacobini
- University of Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Postnatal Brain, Lille Neuroscience & Cognition, UMR-S1172, FHU 1000 Days for Health, 59000 Lille, France
| | - David Blum
- University of Lille, Inserm, CHU Lille, UMR-S1172 LilNCog - Lille Neuroscience & Cognition, Lille, France; Alzheimer and Tauopathies, LabEx DISTALZ, France
| | - Karine Merienne
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France
| | - Tapas K Kundu
- Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
| | - Anne-Laurence Boutillier
- University of Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France; CNRS, UMR7364 - Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg F-67000, France.
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Mlinac-Jerkovic K, Kalanj-Bognar S, Heffer M, Blažetić S. Methodological Pitfalls of Investigating Lipid Rafts in the Brain: What Are We Still Missing? Biomolecules 2024; 14:156. [PMID: 38397393 PMCID: PMC10886647 DOI: 10.3390/biom14020156] [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: 12/31/2023] [Revised: 01/21/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
The purpose of this review is to succinctly examine the methodologies used in lipid raft research in the brain and to highlight the drawbacks of some investigative approaches. Lipid rafts are biochemically and biophysically different from the bulk membrane. A specific lipid environment within membrane domains provides a harbor for distinct raftophilic proteins, all of which in concert create a specialized platform orchestrating various cellular processes. Studying lipid rafts has proved to be arduous due to their elusive nature, mobility, and constant dynamic reorganization to meet the cellular needs. Studying neuronal lipid rafts is particularly cumbersome due to the immensely complex regional molecular architecture of the central nervous system. Biochemical fractionation, performed with or without detergents, is still the most widely used method to isolate lipid rafts. However, the differences in solubilization when various detergents are used has exposed a dire need to find more reliable methods to study particular rafts. Biochemical methods need to be complemented with other approaches such as live-cell microscopy, imaging mass spectrometry, and the development of specific non-invasive fluorescent probes to obtain a more complete image of raft dynamics and to study the spatio-temporal expression of rafts in live cells.
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Affiliation(s)
| | | | - Marija Heffer
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia
| | - Senka Blažetić
- Department of Biology, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia
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Meza U, Romero-Méndez C, Sánchez-Armáss S, Rodríguez-Menchaca AA. Role of rafts in neurological disorders. Neurologia 2023; 38:671-680. [PMID: 37858892 DOI: 10.1016/j.nrleng.2023.10.003] [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: 09/03/2020] [Accepted: 01/01/2021] [Indexed: 10/21/2023] Open
Abstract
INTRODUCTION Rafts are protein-lipid structural nanodomains involved in efficient signal transduction and the modulation of physiological processes of the cell plasma membrane. Raft disruption in the nervous system has been associated with a wide range of disorders. DEVELOPMENT We review the concept of rafts, the nervous system processes in which they are involved, and their role in diseases such as Parkinson's disease, Alzheimer disease, and Huntington disease. CONCLUSIONS Based on the available evidence, preservation and/or reconstitution of rafts is a promising treatment strategy for a wide range of neurological disorders.
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Affiliation(s)
- U Meza
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México.
| | - C Romero-Méndez
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México.
| | - S Sánchez-Armáss
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México.
| | - A A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México.
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Comaposada-Baró R, Benito-Martínez A, Escribano-Saiz JJ, Franco ML, Ceccarelli L, Calatayud-Baselga I, Mira H, Vilar M. Cholinergic neurodegeneration and cholesterol metabolism dysregulation by constitutive p75 NTR signaling in the p75 exonIII-KO mice. Front Mol Neurosci 2023; 16:1237458. [PMID: 37900943 PMCID: PMC10611523 DOI: 10.3389/fnmol.2023.1237458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/28/2023] [Indexed: 10/31/2023] Open
Abstract
Degeneration of basal forebrain cholinergic neurons (BFCNs) is a hallmark of Alzheimer's disease (AD). However, few mouse models of AD recapitulate the neurodegeneration of the cholinergic system. The p75 neurotrophin receptor, p75NTR, has been associated with the degeneration of BFCNs in AD. The senescence-accelerated mouse prone number 8 (SAMP8) is a well-accepted model of accelerated and pathological aging. To gain a better understanding of the role of p75NTR in the basal forebrain during aging, we generated a new mouse line, the SAMP8-p75exonIII-/-. Deletion of p75NTR in the SAMP8 background induces an increase in the number of BFCNs at birth, followed by a rapid decline during aging compared to the C57/BL6 background. This decrease in the number of BFCNs correlates with a worsening in the Y-maze memory test at 6 months in the SAMP8-p75exonIII-/-. We found that SAMP8-p75exonIII-/- and C57/BL6-p75exonIII-/- mice expressed constitutively a short isoform of p75NTR that correlates with an upregulation of the protein levels of SREBP2 and its targets, HMGCR and LDLR, in the BF of both SAMP8-p75exonIII-/- and C57/BL6-p75exonIII-/- mice. As the neurodegeneration of the cholinergic system and the dysregulation of cholesterol metabolism are implicated in AD, we postulate that the generated SAMP8-p75exonIII-/- mouse strain might constitute a good model to study long-term cholinergic neurodegeneration in the CNS. In addition, our results support the role of p75NTR signaling in cholesterol biosynthesis regulation.
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Affiliation(s)
- Raquel Comaposada-Baró
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Andrea Benito-Martínez
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Juan Julian Escribano-Saiz
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - María Luisa Franco
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Lorenzo Ceccarelli
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | | | - Helena Mira
- Stem Cells and Aging Units of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Marçal Vilar
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
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Parente M, Tonini C, Segatto M, Pallottini V. Regulation of cholesterol metabolism: New players for an old physiological process. J Cell Biochem 2023; 124:1449-1465. [PMID: 37796135 DOI: 10.1002/jcb.30477] [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: 06/25/2023] [Revised: 08/30/2023] [Accepted: 09/12/2023] [Indexed: 10/06/2023]
Abstract
Identified more than two centuries ago, cholesterol plays a pivotal role in human physiology. Since cholesterol metabolism is a physiologically significant process, it is not surprising that its alterations are associated with several pathologies. The discovery of new molecular targets or compounds able to modulate this sophisticated metabolism has been capturing the attention of research groups worldwide since many years. Endogenous and exogenous compounds are known to regulate cellular cholesterol synthesis and uptake, or reduce cholesterol absorption at the intestinal level, thereby regulating cholesterol homeostasis. However, there is a great need of new modulators and diverse new pathways have been uncovered. Here, after illustrating cholesterol metabolism and its well-known regulators, some new players of this important physiological process are also described.
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Affiliation(s)
| | | | - Marco Segatto
- Department of Bioscience and Territory, University of Molise, Pesche, Italy
| | - Valentina Pallottini
- Department of Science, University Roma Tre, Rome, Italy
- Neuroendocrinology Metabolism and Neuropharmacology Unit, IRCSS Fondazione Santa Lucia, Via del Fosso Fiorano, Rome, Italy
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Korade Z, Heffer M, Mirnics K. Medication effects on developmental sterol biosynthesis. Mol Psychiatry 2022; 27:490-501. [PMID: 33820938 PMCID: PMC8490477 DOI: 10.1038/s41380-021-01074-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/01/2021] [Accepted: 03/19/2021] [Indexed: 02/01/2023]
Abstract
Cholesterol is essential for normal brain function and development. Genetic disruptions of sterol biosynthesis result in intellectual and developmental disabilities. Developing neurons synthesize their own cholesterol, and disruption of this process can occur by both genetic and chemical mechanisms. Many commonly prescribed medications interfere with sterol biosynthesis, including haloperidol, aripiprazole, cariprazine, fluoxetine, trazodone and amiodarone. When used during pregnancy, these compounds might have detrimental effects on the developing brain of the offspring. In particular, inhibition of dehydrocholesterol-reductase 7 (DHCR7), the last enzyme in the biosynthesis pathway, results in accumulation of the immediate cholesterol precursor, 7-dehydrocholesterol (7-DHC). 7-DHC is highly unstable, giving rise to toxic oxysterols; this is particularly pronounced in a mouse model when both the mother and the offspring carry the Dhcr7+/- genotype. Studies of human dermal fibroblasts from individuals who carry DCHR7+/- single allele mutations suggest that the same gene*medication interaction also occurs in humans. The public health relevance of these findings is high, as DHCR7-inhibitors can be considered teratogens, and are commonly used by pregnant women. In addition, sterol biosynthesis inhibiting medications should be used with caution in individuals with mutations in sterol biosynthesis genes. In an age of precision medicine, further research in this area could open opportunities to improve patient and fetal/infant safety by tailoring medication prescriptions according to patient genotype and life stage.
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Affiliation(s)
- Zeljka Korade
- Department of Pediatrics, College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA, 68198.,Biochemistry and Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA, 68198
| | - Marija Heffer
- J. J. Strossmayer University of Osijek, Faculty of Medicine Osijek, Department of Medical Biology and Genetics, Josipa Huttlera 4, 31000 Osijek, Croatia
| | - Károly Mirnics
- Biochemistry and Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA. .,Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, NE, 68105, USA.
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7
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Follis RM, Tep C, Genaro-Mattos TC, Kim ML, Ryu JC, Morrison VE, Chan JR, Porter N, Carter BD, Yoon SO. Metabolic Control of Sensory Neuron Survival by the p75 Neurotrophin Receptor in Schwann Cells. J Neurosci 2021; 41:8710-8724. [PMID: 34507952 PMCID: PMC8528492 DOI: 10.1523/jneurosci.3243-20.2021] [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: 12/31/2020] [Revised: 08/28/2021] [Accepted: 08/30/2021] [Indexed: 11/21/2022] Open
Abstract
We report that the neurotrophin receptor p75 contributes to sensory neuron survival through the regulation of cholesterol metabolism in Schwann cells. Selective deletion of p75 in mouse Schwann cells of either sex resulted in a 30% loss of dorsal root ganglia (DRG) neurons and diminished thermal sensitivity. P75 regulates Schwann cell cholesterol biosynthesis in response to BDNF, forming a co-receptor complex with ErbB2 and activating ErbB2-mediated stimulation of sterol regulatory element binding protein 2 (SREBP2), a master regulator of cholesterol synthesis. Schwann cells lacking p75 exhibited decreased activation of SREBP2 and a reduction in 7-dehydrocholesterol (7-DHC) reductase (DHCR7) expression, resulting in accumulation of the neurotoxic intermediate, 7-dehyrocholesterol in the sciatic nerve. Restoration of DHCR7 in p75 null Schwann cells in mice significantly attenuated DRG neuron loss. Together, these results reveal a mechanism by which the disruption of lipid metabolism in glial cells negatively influences sensory neuron survival, which has implications for a wide range of peripheral neuropathies.SIGNIFICANCE STATEMENT Although expressed in Schwann cells, the role of p75 in myelination has remained unresolved in part because of its dual expression in sensory neurons that Schwann cells myelinate. When p75 was deleted selectively among Schwann cells, myelination was minimally affected, while sensory neuron survival was reduced by 30%. The phenotype is mainly due to dysregulation of cholesterol biosynthesis in p75-deficient Schwann cells, leading to an accumulation of neurotoxic cholesterol precursor, 7-dehydrocholesterol (7-DHC). Mechanism-wise, we discovered that in response to BDNF, p75 recruits and activates ErbB2 independently of ErbB3, thereby stimulating the master regulator, sterol regulatory element binding protein 2 (SREBP2). These results together highlight a novel role of p75 in Schwann cells in regulating DRG neuron survival by orchestrating proper cholesterol metabolism.
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Affiliation(s)
- Rose M Follis
- Department of Biochemistry, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Chhavy Tep
- Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, Ohio
| | - Thiago C Genaro-Mattos
- Department of Chemistry, Vanderbilt University School of Arts and Sciences, Nashville, Tennessee 37232
| | - Mi Lyang Kim
- Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, Ohio
| | - Jae Cheon Ryu
- Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, Ohio
| | - Vivianne E Morrison
- Department of Biochemistry, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Jonah R Chan
- Department of Neurology, University of California San Francisco, San Francisco, California 94158
| | - Ned Porter
- Department of Chemistry, Vanderbilt University School of Arts and Sciences, Nashville, Tennessee 37232
| | - Bruce D Carter
- Department of Biochemistry, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Sung Ok Yoon
- Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, Ohio
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Colardo M, Martella N, Pensabene D, Siteni S, Di Bartolomeo S, Pallottini V, Segatto M. Neurotrophins as Key Regulators of Cell Metabolism: Implications for Cholesterol Homeostasis. Int J Mol Sci 2021; 22:5692. [PMID: 34073639 PMCID: PMC8198482 DOI: 10.3390/ijms22115692] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/14/2022] Open
Abstract
Neurotrophins constitute a family of growth factors initially characterized as predominant mediators of nervous system development, neuronal survival, regeneration and plasticity. Their biological activity is promoted by the binding of two different types of receptors, leading to the generation of multiple and variegated signaling cascades in the target cells. Increasing evidence indicates that neurotrophins are also emerging as crucial regulators of metabolic processes in both neuronal and non-neuronal cells. In this context, it has been reported that neurotrophins affect redox balance, autophagy, glucose homeostasis and energy expenditure. Additionally, the trophic support provided by these secreted factors may involve the regulation of cholesterol metabolism. In this review, we examine the neurotrophins' signaling pathways and their effects on metabolism by critically discussing the most up-to-date information. In particular, we gather experimental evidence demonstrating the impact of these growth factors on cholesterol metabolism.
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Affiliation(s)
- Mayra Colardo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Noemi Martella
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Daniele Pensabene
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Silvia Siteni
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA;
| | - Sabrina Di Bartolomeo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Valentina Pallottini
- Department of Science, University Roma Tre, Viale Marconi 446, 00146 Rome, Italy;
- Neuroendocrinology Metabolism and Neuropharmacology Unit, IRCSS Fondazione Santa Lucia, Via del Fosso Fiorano 64, 00143 Rome, Italy
| | - Marco Segatto
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
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9
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Meza U, Romero-Méndez C, Sánchez-Armáss S, Rodríguez-Menchaca AA. Role of rafts in neurological disorders. Neurologia 2021; 38:S0213-4853(21)00024-4. [PMID: 33726969 DOI: 10.1016/j.nrl.2021.01.008] [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: 09/03/2020] [Revised: 11/12/2020] [Accepted: 01/01/2021] [Indexed: 11/21/2022] Open
Abstract
INTRODUCTION Rafts are function-structural cell membrane nano-domains. They contribute to explain the efficiency of signal transduction at the low physiological membrane concentrations of the signaling partners by their clustering inside specialized signaling domains. DEVELOPMENT In this article, we review the current model of the membrane rafts and their physio-pathological relevance in the nervous system, including their role in Parkinson, Alzheimer, and Huntington diseases. CONCLUSIONS Rafts disruption/dysfunction has been shown to relate diverse neurological diseases. Therefore, it has been suggested that preservation of membrane rafts may represent a strategy to prevent or delay neuronal dysfunctions in several diseases.
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Affiliation(s)
- U Meza
- Departamento de Fisiología y Biofísica. Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México.
| | - C Romero-Méndez
- Departamento de Fisiología y Biofísica. Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - S Sánchez-Armáss
- Departamento de Fisiología y Biofísica. Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - A A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica. Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
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Allen LB, Genaro-Mattos TC, Porter NA, Mirnics K, Korade Z. Desmosterolosis and desmosterol homeostasis in the developing mouse brain. J Inherit Metab Dis 2019; 42:934-943. [PMID: 30891795 PMCID: PMC6739189 DOI: 10.1002/jimd.12088] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 03/14/2019] [Indexed: 01/04/2023]
Abstract
Cholesterol serves as a building material for cellular membranes and plays an important role in cellular metabolism. The brain relies on its own cholesterol biosynthesis, which starts during embryonic development. Cholesterol is synthesized from two immediate precursors, desmosterol and 7-dehydrocholesterol (7-DHC). Mutations in the DHCR24 enzyme, which converts desmosterol into cholesterol, lead to desmosterolosis, an autosomal recessive developmental disorder. In this study, we assessed the brain content of desmosterol, 7-DHC, and cholesterol from development to adulthood, and analyzed the biochemical, molecular, and anatomical consequences of Dhcr24 mutations on the sterol profile in a mouse model of desmosterolosis and heterozygous Dhcr24+/- carriers. Our HPLC-MS/MS studies revealed that by P0 desmosterol almost entirely replaced cholesterol in the Dhcr24-KO brain. The greatly elevated desmosterol levels were also present in the Dhcr24-Het brains irrespective of maternal genotype, persisting into adulthood. Furthermore, Dhcr24-KO mice brains showed complex changes in expression of lipid and sterol transcripts, nuclear receptors, and synaptic plasticity transcripts. Cultured Dhcr24-KO neurons showed increased arborization, which was also present in the Dhcr24-KO mouse brains. Finally, we observed a shared pathophysiological mechanism between the mouse models of desmosterolosis and Smith-Lemli-Opitz syndrome (a genetic disorder of conversion of 7-DHC to cholesterol).
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Affiliation(s)
- Luke B. Allen
- Department of Pediatrics, Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE
| | - Thiago C. Genaro-Mattos
- Munroe-Meyer Institute, Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE
| | - Ned A. Porter
- Department of Chemistry, Vanderbilt Institute of Chemical Biology and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN
| | - Károly Mirnics
- Munroe-Meyer Institute, Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE
| | - Zeljka Korade
- Department of Pediatrics, Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE
- Corresponding Author: Zeljka Korade, DVM, PhD, ; 982165 Nebraska Medicine Center, Omaha, 68198-2165
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Genaro-Mattos TC, Anderson A, Allen LB, Korade Z, Mirnics K. Cholesterol Biosynthesis and Uptake in Developing Neurons. ACS Chem Neurosci 2019; 10:3671-3681. [PMID: 31244054 PMCID: PMC7184320 DOI: 10.1021/acschemneuro.9b00248] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Brain cholesterol biosynthesis, a separate and distinct process from whole-body cholesterol homeostasis, starts during embryonic development. To gain a better understanding of the neuronal and glial contributions to the brain cholesterol pool, we studied this process in control, Dhcr7-/-, and Dhcr24-/- cell cultures. Our LC-MS/MS method allowed us to measure several different sterol intermediates and cholesterol during neuronal differentiation. We found that developing cortical neurons rely on endogenous cholesterol synthesis and utilize ApoE-complexed cholesterol and sterol precursors from their surroundings. Both developing neurons and astrocytes release cholesterol into their local environment. Our studies also uncovered that developing neurons produced significantly higher amounts of cholesterol per cell than the astrocytes. Finally, we established that both neurons and astroglia preferentially use the Bloch sterol biosynthesis pathway, where desmosterol is the immediate precursor to cholesterol. Overall, our studies suggest that endogenous sterol synthesis in developing neurons is a critical and complexly regulated homeostatic process during brain development.
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Affiliation(s)
- Thiago C. Genaro-Mattos
- Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, Nebraska 68105, United States
| | - Allison Anderson
- Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, Nebraska 68105, United States
| | - Luke B. Allen
- Department of Pediatrics, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
| | - Zeljka Korade
- Department of Pediatrics, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States,Corresponding Authors:.
| | - Károly Mirnics
- Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, Nebraska 68105, United States,Corresponding Authors:.
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12
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Bovio PP, Franz H, Heidrich S, Rauleac T, Kilpert F, Manke T, Vogel T. Differential Methylation of H3K79 Reveals DOT1L Target Genes and Function in the Cerebellum In Vivo. Mol Neurobiol 2018; 56:4273-4287. [PMID: 30302725 PMCID: PMC6505521 DOI: 10.1007/s12035-018-1377-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 10/01/2018] [Indexed: 12/21/2022]
Abstract
The disruptor of telomeric silencing 1-like (DOT1L) mediates methylation of histone H3 at position lysine 79 (H3K79). Conditional knockout of Dot1l in mouse cerebellar granule cells (Dot1l-cKOAtoh1) led to a smaller external granular layer with fewer precursors of granule neurons. Dot1l-cKOAtoh1 mice had impaired proliferation and differentiation of granular progenitors, which resulted in a smaller cerebellum. Mutant mice showed mild ataxia in motor behavior tests. In contrast, Purkinje cell-specific conditional knockout mice showed no obvious phenotype. Genome-wide transcription analysis of Dot1l-cKOAtoh1 cerebella using microarrays revealed changes in genes that function in cell cycle, cell migration, axon guidance, and metabolism. To identify direct DOT1L target genes, we used genome-wide profiling of H3K79me2 and transcriptional analysis. Analysis of differentially methylated regions (DR) and differentially expressed genes (DE) revealed in total 12 putative DOT1L target genes in Dot1l-cKOAtoh1 affecting signaling (Tnfaip8l3, B3galt5), transcription (Otx1), cell migration and axon guidance (Sema4a, Sema5a, Robo1), cholesterol and lipid metabolism (Lss, Cyp51), cell cycle (Cdkn1a), calcium-dependent cell-adhesion or exocytosis (Pcdh17, Cadps2), and unknown function (Fam174b). Dysregulated expression of these target genes might be implicated in the ataxia phenotype observed in Dot1l-cKOAtoh1.
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Affiliation(s)
- Patrick Piero Bovio
- Institute for Anatomy and Cell Biology, Department of Molecular Embryology, Medical Faculty, University of Freiburg, 79104, Freiburg, Germany.,Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Henriette Franz
- Institute for Anatomy and Cell Biology, Department of Molecular Embryology, Medical Faculty, University of Freiburg, 79104, Freiburg, Germany
| | - Stefanie Heidrich
- Institute for Anatomy and Cell Biology, Department of Molecular Embryology, Medical Faculty, University of Freiburg, 79104, Freiburg, Germany
| | - Tudor Rauleac
- Institute for Anatomy and Cell Biology, Department of Molecular Embryology, Medical Faculty, University of Freiburg, 79104, Freiburg, Germany
| | - Fabian Kilpert
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg, Germany
| | - Thomas Manke
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg, Germany
| | - Tanja Vogel
- Institute for Anatomy and Cell Biology, Department of Molecular Embryology, Medical Faculty, University of Freiburg, 79104, Freiburg, Germany.
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13
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Korade Z, Genaro-Mattos TC, Tallman KA, Liu W, Garbett KA, Koczok K, Balogh I, Mirnics K, Porter NA. Vulnerability of DHCR7+/- mutation carriers to aripiprazole and trazodone exposure. J Lipid Res 2017; 58:2139-2146. [PMID: 28972118 DOI: 10.1194/jlr.m079475] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/19/2017] [Indexed: 12/20/2022] Open
Abstract
Smith-Lemli-Opitz syndrome is a recessive disorder caused by mutations in 7-dehydrocholesterol reductase (DHCR)7 with a heterozygous (HET) carrier frequency of 1-3%. A defective DHCR7 causes accumulation of 7-dehydrocholesterol (DHC), which is a highly oxidizable and toxic compound. Recent studies suggest that several antipsychotics, including the highly prescribed pharmaceuticals, aripiprazole (ARI) and trazodone (TRZ), increase 7-DHC levels in vitro and in humans. Our investigation was designed to compare the effects of ARI and TRZ on cholesterol (Chol) synthesis in fibroblasts from DHCR7+/- human carriers and controls (CTRs). Six matched pairs of fibroblasts were treated and their sterol profile analyzed by LC-MS. Significantly, upon treatment with ARI and TRZ, the total accumulation of 7-DHC was higher in DHCR7-HET cells than in CTR fibroblasts. The same set of experiments was repeated in the presence of 13C-lanosterol to determine residual Chol synthesis, revealing that ARI and TRZ strongly inhibit de novo Chol biosynthesis. The results suggest that DHCR7 carriers have increased vulnerability to both ARI and TRZ exposure compared with CTRs. Thus, the 1-3% of the population who are DHCR7 carriers may be more likely to sustain deleterious health consequences on exposure to compounds like ARI and TRZ that increase levels of 7-DHC, especially during brain development.
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Affiliation(s)
- Zeljka Korade
- Departments of Pediatrics and Biochemistry and Molecular Biology University of Nebraska Medical Center, Omaha, NE 68198
| | - Thiago C Genaro-Mattos
- Department of Chemistry and Vanderbilt Institute of Chemical Biology Vanderbilt University, Nashville, TN 37235
| | - Keri A Tallman
- Department of Chemistry and Vanderbilt Institute of Chemical Biology Vanderbilt University, Nashville, TN 37235
| | - Wei Liu
- Department of Chemistry and Vanderbilt Institute of Chemical Biology Vanderbilt University, Nashville, TN 37235
| | | | - Katalin Koczok
- Department of Laboratory Medicine, Division of Clinical Genetics, University of Debrecen, Debrecen 4032, Hungary
| | - Istvan Balogh
- Department of Laboratory Medicine, Division of Clinical Genetics, University of Debrecen, Debrecen 4032, Hungary
| | - Karoly Mirnics
- Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, NE 68198
| | - Ned A Porter
- Department of Chemistry and Vanderbilt Institute of Chemical Biology Vanderbilt University, Nashville, TN 37235
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14
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Oswald M, Geissler S, Goepferich A. Targeting the Central Nervous System (CNS): A Review of Rabies Virus-Targeting Strategies. Mol Pharm 2017; 14:2177-2196. [DOI: 10.1021/acs.molpharmaceut.7b00158] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Mira Oswald
- Chemical & Pharmaceutical Development, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Simon Geissler
- Chemical & Pharmaceutical Development, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Achim Goepferich
- Department for Pharmaceutical Technology, University of Regensburg, Universitätsstraße 31, 94030 Regensburg, Germany
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15
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Moutinho M, Nunes MJ, Rodrigues E. The mevalonate pathway in neurons: It's not just about cholesterol. Exp Cell Res 2017; 360:55-60. [PMID: 28232115 DOI: 10.1016/j.yexcr.2017.02.034] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 02/20/2017] [Indexed: 11/26/2022]
Abstract
Cholesterol homeostasis greatly impacts neuronal function due to the essential role of this sterol in the brain. The mevalonate (MVA) pathway leads to the synthesis of cholesterol, but also supplies cells with many other intermediary molecules crucial for neuronal function. Compelling evidence point to a model in which neurons shutdown cholesterol synthesis, and rely on a shuttle derived from astrocytes to meet their cholesterol needs. Nevertheless, several reports suggest that neurons maintain the MVA pathway active, even with sustained cholesterol supply by astrocytes. Hence, in this review we focus not on cholesterol production, but rather on the role of the MVA pathway in the synthesis of particular intermediaries, namely isoprenoids, and on their role on neuronal function. Isoprenoids act as anchors for membrane association, after being covalently bound to proteins, such as most of the small guanosine triphosphate-binding proteins, which are critical to neuronal cell function. Based on literature, on our own results, and on the analysis of public transcriptomics databases, we raise the idea that in neurons there is a shift of the MVA pathway towards the non-sterol branch, responsible for isoprenoid synthesis, in detriment to post-squalene branch, and that this is ultimately essential for synaptic activity. Nevertheless new tools that facilitate imaging and the biochemical characterization and quantification of the prenylome in neurons and astrocytes are needed to understand the regulation of isoprenoid production and protein prenylation in the brain, and to analyze its differences on diverse physiological or pathological conditions, such as aging and neurodegenerative states.
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Affiliation(s)
- Miguel Moutinho
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Portugal, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Maria João Nunes
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Portugal, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Elsa Rodrigues
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Portugal, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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16
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Lotta LT, Conrad K, Cory-Slechta D, Schor NF. Cerebellar Purkinje cell p75 neurotrophin receptor and autistic behavior. Transl Psychiatry 2014; 4:e416. [PMID: 25072321 PMCID: PMC4119222 DOI: 10.1038/tp.2014.55] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 04/24/2014] [Accepted: 05/21/2014] [Indexed: 01/19/2023] Open
Abstract
The p75 neurotrophin receptor (p75NTR) is normally expressed in cerebellar Purkinje cells throughout the lifespan. Children with autism spectrum behavior exhibit apparent cerebellar Purkinje cell loss. Cerebellar transcriptome changes seen in the murine prenatal valproate exposure model of autism include all of the proteins known to constitute the p75NTR interactome. p75NTR is a modulator of cytoplasmic and mitochondrial redox potential, and others have suggested that aberrant response to oxidant stress has a major role in the pathogenesis of autism. We have created Purkinje cell-selective p75NTR knockout mice that are the progeny of hemizygous Cre-Purkinje cell protein 2 C57Bl mice and p75NTR floxed C57Bl mice. These Cre-loxP mice exhibit complete knockout of p75NTR in ~50% of the cerebellar Purkinje cells. Relative to Cre-only mice and wild-type C57Bl mice, this results in a behavioral phenotype characterized by less allogrooming of (P<0.05; one-way analysis of variance) and socialization or fighting with (each P<0.05) other mice; less (1.2-fold) non-ambulatory exploration of their environment than wild-type (P<0.01) or Cre only (P<0.01) mice; and almost twofold more stereotyped jumping behavior than wild-type (P<0.05) or Cre (P<0.02) mice of the same strain. Wild-type mice have more complex dendritic arborization than Cre-loxP mice, with more neurites per unit area (P<0.025, Student's t-test), more perpendicular branches per unit area (P<0.025) and more short branches/long neurite (P<0.0005). Aberrant developmental regulation of expression of p75NTR in cerebellar Purkinje cells may contribute to the pathogenesis of autism.
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Affiliation(s)
- L T Lotta
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - K Conrad
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - D Cory-Slechta
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - N F Schor
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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17
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Abstract
In times of fiscal austerity, the tendency is to seek instant, inexpensive gratification. In the case of biomedical research, this means the shortest path to practical clinical implementation. But fueling the translational pipeline with discovery depends critically on allowing the biomedical research community to follow their science where it takes them. Fiscal constraints carry with them the risk of squelching creativity and forfeiting the power of serendipity to provide the substrate for the translational engine in the future.
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Affiliation(s)
- Nina F Schor
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
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18
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Abstract
Neuroblastoma is, at once, the most common and deadly extracranial solid tumor of childhood. Efforts aimed at targeting the neural characteristics of these tumors have taught us much about neural crest cell biology, apoptosis induction in the nervous system, and neurotrophin receptor signaling and intracellular processing. But neuroblastoma remains a formidable enemy to the oncologist and an enigmatic target to the neuroscientist.
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Affiliation(s)
- Nina F Schor
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
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19
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Hung YH, Bush AI, La Fontaine S. Links between copper and cholesterol in Alzheimer's disease. Front Physiol 2013; 4:111. [PMID: 23720634 PMCID: PMC3655288 DOI: 10.3389/fphys.2013.00111] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/30/2013] [Indexed: 01/01/2023] Open
Abstract
Altered copper homeostasis and hypercholesterolemia have been identified independently as risk factors for Alzheimer's disease (AD). Abnormal copper and cholesterol metabolism are implicated in the genesis of amyloid plaques and neurofibrillary tangles (NFT), which are two key pathological signatures of AD. Amyloidogenic processing of a sub-population of amyloid precursor protein (APP) that produces Aβ occurs in cholesterol-rich lipid rafts in copper deficient AD brains. Co-localization of Aβ and a paradoxical high concentration of copper in lipid rafts fosters the formation of neurotoxic Aβ:copper complexes. These complexes can catalytically oxidize cholesterol to generate H2O2, oxysterols and other lipid peroxidation products that accumulate in brains of AD cases and transgenic mouse models. Tau, the core protein component of NFTs, is sensitive to interactions with copper and cholesterol, which trigger a cascade of hyperphosphorylation and aggregation preceding the generation of NFTs. Here we present an overview of copper and cholesterol metabolism in the brain, and how their integrated failure contributes to development of AD.
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Affiliation(s)
- Ya Hui Hung
- Oxidation Biology Laboratory, Florey Institute of Neuroscience and Mental Health Parkville, VIC, Australia ; Centre for Neuroscience Research, The University of Melbourne Parkville, VIC, Australia
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20
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Cholesterol: its regulation and role in central nervous system disorders. CHOLESTEROL 2012; 2012:292598. [PMID: 23119149 PMCID: PMC3483652 DOI: 10.1155/2012/292598] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/03/2012] [Accepted: 09/10/2012] [Indexed: 02/08/2023]
Abstract
Cholesterol is a major constituent of the human brain, and the brain is the most cholesterol-rich organ. Numerous lipoprotein receptors and apolipoproteins are expressed in the brain. Cholesterol is tightly regulated between the major brain cells and is essential for normal brain development. The metabolism of brain cholesterol differs markedly from that of other tissues. Brain cholesterol is primarily derived by de novo synthesis and the blood brain barrier prevents the uptake of lipoprotein cholesterol from the circulation. Defects in cholesterol metabolism lead to structural and functional central nervous system diseases such as Smith-Lemli-Opitz syndrome, Niemann-Pick type C disease, and Alzheimer's disease. These diseases affect different metabolic pathways (cholesterol biosynthesis, lipid transport and lipoprotein assembly, apolipoproteins, lipoprotein receptors, and signaling molecules). We review the metabolic pathways of cholesterol in the CNS and its cell-specific and microdomain-specific interaction with other pathways such as the amyloid precursor protein and discuss potential treatment strategies as well as the effects of the widespread use of LDL cholesterol-lowering drugs on brain functions.
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21
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Milagre I, Olin M, Nunes MJ, Moutinho M, Lövgren-Sandblom A, Gama MJ, Björkhem I, Rodrigues E. Marked change in the balance between CYP27A1 and CYP46A1 mediated elimination of cholesterol during differentiation of human neuronal cells. Neurochem Int 2012; 60:192-8. [DOI: 10.1016/j.neuint.2011.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 11/29/2011] [Accepted: 12/05/2011] [Indexed: 11/30/2022]
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22
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Xu L, Mirnics K, Bowman AB, Liu W, Da J, Porter NA, Korade Z. DHCEO accumulation is a critical mediator of pathophysiology in a Smith-Lemli-Opitz syndrome model. Neurobiol Dis 2011; 45:923-9. [PMID: 22182693 DOI: 10.1016/j.nbd.2011.12.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 10/25/2011] [Accepted: 12/04/2011] [Indexed: 11/19/2022] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is an inborn error of metabolism caused by defective cholesterol biosynthesis. Mutations within the gene encoding 7-dehydrocholesterol reductase (DHCR7), the last enzyme in the pathway, lead to the accumulation of 7-dehydrocholesterol (7-DHC) in the brain tissue and blood of the SLOS patients. The objective of this study was to determine the consequences of the accumulation of an immediate cholesterol precursor, 7-DHC and its oxysterol metabolite, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), in the brain tissue of Dhcr7-KO mouse, a model for SLOS. We found that cholesterol, 7-DHC and DHCEO show region-specific distribution, suggesting that the midbrain and the cortex are the primary sites of vulnerability. We also report that neurons are ten fold more susceptible to a 7-DHC-derived oxysterol mixture than glial cells, and that DHCEO accelerates differentiation and arborization of cortical neurons. The overall results suggest that 7-DHC oxidative metabolites are critical contributors to altered neural development in SLOS. The future studies will test if antioxidant supplementation will ameliorate some of the clinical symptoms associated with this devastating disease.
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Affiliation(s)
- Libin Xu
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
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23
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Mailman T, Hariharan M, Karten B. Inhibition of neuronal cholesterol biosynthesis with lovastatin leads to impaired synaptic vesicle release even in the presence of lipoproteins or geranylgeraniol. J Neurochem 2011; 119:1002-15. [PMID: 21899539 DOI: 10.1111/j.1471-4159.2011.07474.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cholesterol is highly enriched in the brain, and plays a key role in synapse formation and function. The brain does not derive cholesterol from the circulation; instead, the majority of cholesterol is made in glia and secreted in form of lipoproteins. Neurons can synthesize cholesterol, but the extent of neuronal cholesterol biosynthesis in the adult brain is unknown. Cholesterol biosynthesis inhibitors of the statin family are widely used to lower circulating cholesterol and cardiovascular risk. Lipophilic statins can cross the blood brain barrier and inhibit brain cholesterol biosynthesis with possible consequences for synaptic cholesterol homeostasis. We have investigated the effects of lovastatin on synapse maturation and synaptic vesicle release. Treatment of primary hippocampal neurons with low levels of lovastatin for one week reduced synapse density and impaired synaptic vesicle release. Neither lipoproteins nor geranylgeraniol fully counteracted the lovastatin-induced decrease of synaptic vesicle exocytosis, even when cholesterol depletion was prevented. In contrast, restoration of neuronal cholesterol synthesis with mevalonate prevented defects in vesicle exocytosis without fully normalizing neuronal cholesterol content. These results raise the possibility that chronic exposure of neurons to lipophilic statins may affect synaptic transmission, and indicate that hippocampal neurons need a certain level of endogenous cholesterol biosynthesis.
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Affiliation(s)
- Tiffany Mailman
- Department of Biochemistry and Molecular Biology and Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia, Canada
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24
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Qazi A, Halterman MW, Mi Z, Zhang T, Schor NF. Chopper is prodeath regardless of the effect of p75ICD on sensitivity to oxidative stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2011; 2011:391659. [PMID: 21904642 PMCID: PMC3166776 DOI: 10.1155/2011/391659] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 06/21/2011] [Accepted: 06/23/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND The intracellular domain (ICD) of the neurotrophin receptor, p75NTR, exhibits variably pro- and antiapoptotic activity and has been implicated in neurodegenerative and neurodestructive disease. The molecular determinants of these cellular effects are not completely understood. The "Chopper" domain of p75ICD has been shown to be proapoptotic in in vitro systems in which p75ICD is proapoptotic. The effects of Chopper in systems in which p75ICD is antiapoptotic and, therefore, whether or not Chopper accounts for the variability of the cellular effects of p75ICD are not known. We therefore examined the effects of deletion of Chopper on the effects of p75ICD on in vitro cell culture systems in which p75ICD is pro- or antiapoptotic, respectively. RESULTS In HN33.11 murine neuroblastoma-hippocampal neuron hybrid cells, p75ICD is antiapoptotic. In NIH 3T3 cells, p75ICD is proapoptotic. In both cell lines deletion of the Chopper domain from p75ICD decreases the incidence of apoptosis resulting from oxidative stress. Thus, irrespective of the nature of the effects of p75ICD on the cell, its Chopper domain is proapoptotic. CONCLUSIONS Expression of p75ICD can enhance or attenuate oxidative induction of apoptosis. Variability of the effects of p75ICD is not related to variability of the effects of its Chopper domain.
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Affiliation(s)
- Alliya Qazi
- Department of Pediatrics, Golisano Children's Hospital at URMC, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Marc W. Halterman
- Department of Pediatrics, Golisano Children's Hospital at URMC, University of Rochester Medical Center, Rochester, NY 14642, USA
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA
- The Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Zhiping Mi
- Department of Pediatrics, Golisano Children's Hospital at URMC, University of Rochester Medical Center, Rochester, NY 14642, USA
- The Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Tong Zhang
- Department of Pediatrics, Golisano Children's Hospital at URMC, University of Rochester Medical Center, Rochester, NY 14642, USA
- The Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Nina F. Schor
- Department of Pediatrics, Golisano Children's Hospital at URMC, University of Rochester Medical Center, Rochester, NY 14642, USA
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA
- The Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY 14642, USA
- Departments of Neurobiology & Anatomy, University of Rochester Medical Center, Rochester, NY 14642, USA
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25
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Schor NF. What the halted phase III γ-secretase inhibitor trial may (or may not) be telling us. Ann Neurol 2011; 69:237-9. [PMID: 21387368 DOI: 10.1002/ana.22365] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The aborted trial of semagacestat has led some to invoke unanticipated effects of γ-secretase inhibition on formation of amyloid β. However, the many substrates for γ-secretases and the varied biological effects of each of the resultant cleavage products make ascribing causality much more complex than that.
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Affiliation(s)
- Nina F Schor
- Department of Pediatrics, University of Rochester Medical Center, Golisano Children's Hospital, NY, USA
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26
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Ingraham CA, Wertalik L, Schor NF. Necdin and neurotrophin receptors: interactors of relevance for neuronal resistance to oxidant stress. Pediatr Res 2011; 69:279-84. [PMID: 21150695 PMCID: PMC3086542 DOI: 10.1203/pdr.0b013e31820a5773] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Necdin is a protein known to interact with the neurotrophin receptors, neurotrophic tyrosine kinase receptor type 1 (TrkA) and 75 kD low-affinity neurotrophin receptor (p75NTR). TrkA and p75NTR play roles in development and disease of the nervous system and chemoresistance of nervous system tumors. Necdin deletion is associated with Prader-Willi syndrome. The present studies demonstrate that the effects of necdin on the susceptibility of neuroblastoma cells to oxidant stress are dependent on the ratio of p75NTR to TrkA in the cell. In low p75NTR:TrkA ratio cells, necdin down-regulation decreases sensitivity to oxidant stress and expression of and signaling through TrkA. In high p75NTR:TrkA cells, necdin down-regulation is without effect. The effects of necdin deletion on the developing nervous system may depend on the relative expression of p75NTR and TrkA in the cells of particular regions of the nervous system.
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Affiliation(s)
- Christopher A Ingraham
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York 14642, USA
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27
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Zhang T, Mi Z, Schor NF. Role of tyrosine phosphorylation in the antioxidant effects of the p75 neurotrophin receptor. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2011; 2:238-46. [PMID: 20716910 PMCID: PMC2763262 DOI: 10.4161/oxim.2.4.9745] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The p75 neurotrophin receptor (p75NTR) is an α-and γ-secretase substrate expressed preferentially in the cholinergic neurons of the nucleus basalis of Meynert, the hippocampus, and the cerebellum of the adult brain. Mutations of the γ-secretase, presenilin, have been implicated in familial Alzheimer's disease. Furthermore, oxidative and inflammatory injury to the cholinergic neurons of the nucleus basalis of Meynert and hippocampus plays a critical role in the pathology of Alzheimer's disease. The intracellular domain of p75NTR (p75ICD) is the α- and γ-secretase cleavage fragment of the holoreceptor that functions as an antioxidant in PC12 rat pheochromocytoma cells. Phosphorylation of the receptor is thought to be necessary for many of its functions, and two tyrosines in p75ICD have been among the functionally important phosphorylation sites. Site-directed mutagenesis was used to generate three p75ICD mutants that cannot be phosphorylated at either or both tyrosines, respectively. Each of these mutants was expressed in p75NTR-deficient PC12 cells to determine the effects of blocking phosphorylation at specific sites on the antioxidant activity of p75ICD. Interfering with phosphorylation at tyrosine-337 impairs antioxidant function, while interfering with phosphorylation at tyrosine-366 does not, and may in fact impart protection from oxidant stress. Neither MAPK (i.e., p38, ERK1, ERK2) content nor NF-κB activation accounts for the differential sensitivity to oxidant stress among the differentially phosphorylated p75NTR cell lines. However, differences in the time course of ERK1,2 phosphorylation among the lines account in large measure for their differential oxidant sensitivity. The phosphorylation state of specific sites on p75ICD may modulate the resistance of neurons in Alzheimer's disease-relevant brain regions to oxidant stress.
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Affiliation(s)
- Tong Zhang
- Department of Pediatrics and the Center for Neural Disease and Degeneration, University of Rochester Medical Center, Rochester, NY 14642, USA
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Valdez CM, Smith MA, Perry G, Phelix CF, Santamaria F. Cholesterol homeostasis markers are localized to mouse hippocampal pyramidal and granule layers. Hippocampus 2010; 20:902-5. [PMID: 20054815 DOI: 10.1002/hipo.20743] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Changes in brain cholesterol homeostasis are associated with multiple diseases, such as Alzheimer's and Huntington's; however, controversy persists as to whether adult neurons produce their own cholesterol, or if it is outsourced to astrocytes. To address this issue, we analyzed 25 genes most immediately involved in cholesterol homeostasis from in situ data provided by the Allen Brain Mouse Atlas. We compared the relative mRNA expression in the pyramidal and granule layers, populated with neurons, with the rest of the hippocampus which is populated with neuronal processes and glia. Comparing the expression of the individual genes to markers for neurons and astrocytes, we found that cholesterol homeostasis genes are preferentially targeted to neuronal layers. Therefore, changes in gene expression levels might affect neuronal populations directly.
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Affiliation(s)
- Chris M Valdez
- Department of Biology, The University of Texas at San Antonio, One UTSA circle, San Antonio, Texas 78249, USA
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Korade Z, Xu L, Shelton R, Porter NA. Biological activities of 7-dehydrocholesterol-derived oxysterols: implications for Smith-Lemli-Opitz syndrome. J Lipid Res 2010; 51:3259-69. [PMID: 20702862 DOI: 10.1194/jlr.m009365] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a metabolic and developmental disorder caused by mutations in the gene encoding the enzyme 7-dehydrocholesterol reductase (Dhcr7). This reductase catalyzes the last step in cholesterol biosynthesis, and levels of 7-dehydrocholesterol (7-DHC), the substrate for this enzyme, are elevated in SLOS patients as a result of this defect. Our group has previously shown that 7-DHC is extremely prone to free radical autoxidation, and we identified about a dozen different oxysterols formed from oxidation of 7-DHC. We report here that 7-DHC-derived oxysterols reduce cell viability in a dose- and time-dependent manner, some of the compounds showing activity at sub-micromolar concentrations. The reduction of cell survival is caused by a combination of reduced proliferation and induced differentiation of the Neuro2a cells. The complex 7-DHC oxysterol mixture added to control Neuro2a cells also triggers the gene expression changes that were previously identified in Dhcr7-deficient Neuro2a cells. Based on the identification of overlapping gene expression changes in Dhcr7-deficient and 7-DHC oxysterol-treated Neuro2a cells, we hypothesize that some of the pathophysiological findings in the mouse SLOS model and SLOS patients might be due to accumulated 7-DHC oxysterols.
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Affiliation(s)
- Zeljka Korade
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
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Darwish DS, Wang D, Konat GW, Schreurs BG. Dietary cholesterol impairs memory and memory increases brain cholesterol and sulfatide levels. Behav Neurosci 2010; 124:115-123. [PMID: 20141286 DOI: 10.1037/a0018253] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cholesterol and sulfatides play many important roles in learning and memory. To date, our observations about the effects of cholesterol on learning have been assessed during response acquisition; that is, the learning of a new memory. Here, we report for the first time to our knowledge, on the effect of a cholesterol diet on a previously formed memory. Rabbits were given trace conditioning of the nictitating membrane response for 10 days, then fed a 2% cholesterol diet for 8 weeks, and then assessed for memory recall of the initially learned task. We show that dietary cholesterol had an adverse effect on memory recall. Second, we investigated whether dietary cholesterol caused an increase in brain cholesterol and sulfatide levels in four major brain structures (hippocampus, frontal lobe, brainstem, and cerebellum) using a technique for analyzing myelin and myelin-free fractions separately. Although our data confirm previous findings that dietary cholesterol does not directly affect cholesterol and establish that it does not affect sulfatide levels in the brain, these levels did increase rather significantly in the hippocampus and frontal lobe as a function of learning and memory.
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Rogers D, Schor NF. The child is father to the man: developmental roles for proteins of importance for neurodegenerative disease. Ann Neurol 2010; 67:151-8. [PMID: 20225270 DOI: 10.1002/ana.21841] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Although Alzheimer's and Parkinson's diseases predominately affect elderly adults, the proteins that play a role in the pathogenesis of these diseases are expressed throughout life. In fact, many of the proteins hypothesized to be important in the progression of neurodegeneration play direct or indirect roles in the development of the central nervous system. The systems affected by these proteins include neural stem cell fate decisions, neuronal differentiation, cellular migration, protection from oxidative stress, and programmed cell death. Insights into the developmental roles of these proteins may ultimately impact the understanding of neurodegenerative diseases and lead to the discovery of novel treatments.
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Affiliation(s)
- Danny Rogers
- Departments of Pediatrics, Neurology, and Neurobiology & Anatomy, University of Rochester Medical Center, Rochester, NY 14642, USA
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Ong WY, Kim JH, He X, Chen P, Farooqui AA, Jenner AM. Changes in brain cholesterol metabolome after excitotoxicity. Mol Neurobiol 2010; 41:299-313. [PMID: 20140539 DOI: 10.1007/s12035-010-8099-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 01/07/2010] [Indexed: 12/15/2022]
Abstract
Excitotoxicity due to excess stimulation of glutamate receptors in neurons is accompanied by increased Ca(2+) influx, stimulation of Ca(2+)-dependent enzymes, ATP depletion, increase in lipid peroxidation products, and loss of glutathione. These changes resemble neurochemical alterations in acute neuronal injury (stroke, spinal cord injury, and traumatic brain injury) and chronic neurodegenerative diseases such as Alzheimer's disease. Intracerebroventricular injection of the potent glutamate analog kainate in rats results in increased cholesterol concentration in the hippocampus at short to medium time intervals, i.e., 3 days-1 week post-injection, as detected by gas chromatography-mass spectrometry in the lesioned hippocampus. This is accompanied by an early increase in levels of cholesterol biosynthetic precursors and increases in both enzymatically derived oxysterols such as 24-hydroxycholesterol and cholesterol oxidation products (COPs) generated by reactive oxygen species, including cholesterol epoxides and 7-ketocholesterol. In contrast to COPs, no change in concentration of the neurosteroid pregnenolone was found after KA injury. Cholesterol and COPs significantly increase exocytosis in cultured PC12 cells and neurons, and both oxysterols and COPs are able to induce cytotoxic and apoptotic injuries in different cell types, including neurons. Together, the findings suggest that increased cholesterol and COPs after KA excitotoxicity could themselves lead to disturbed neuronal ion homeostasis, increased neurotransmitter release, and propagation of excitotoxicity.
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Affiliation(s)
- Wei-Yi Ong
- Department of Anatomy, National University of Singapore, Singapore, 119260, Singapore.
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Cunningham D, Spychala K, McLarren KW, Garza LA, Boerkoel CF, Herman GE. Developmental expression pattern of the cholesterogenic enzyme NSDHL and negative selection of NSDHL-deficient cells in the heterozygous Bpa(1H)/+ mouse. Mol Genet Metab 2009; 98:356-66. [PMID: 19631568 PMCID: PMC2783206 DOI: 10.1016/j.ymgme.2009.06.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 06/30/2009] [Accepted: 06/30/2009] [Indexed: 12/22/2022]
Abstract
NSDHL (NAD(P)H sterol dehydrogenase-like), is a 3beta-hydroxysterol dehydrogenase thought to function in the demethylation of sterol precursors in one of the later steps of cholesterol biosynthesis. Mutations in the X-linked NSDHL gene cause CHILD syndrome in humans, and the male-lethal bare patches (Bpa) phenotype in mice. The relative level of NSDHL expression among different mouse tissues at several stages of embryogenesis and postnatal development was analyzed by immunohistochemistry. In wild type (WT) embryos, the highest levels of expression were seen in the liver, dorsal root ganglia, central nervous system, retina, adrenal gland and testis. Heterozygous Bpa(1H) females are mosaic for NSDHL expression due to normal random X-inactivation. NSDHL-deficient cells were detected in the developing cerebral cortex and retina of Bpa(1H) female embryos. In postnatal WT and Bpa(1H) animals, we compared the expression pattern of NSDHL in skin, an affected tissue; liver, a main site of cholesterol synthesis; and brain, a tissue dependent on endogenous synthesis of cholesterol due to lack of transport across the blood-brain barrier. Clonal populations of mutant cells were visible in the brain, skin and liver of Bpa(1H) pups. In the liver, the proportion of NSDHL negative cells dropped from approximately 50% at postnatal day 6 to approximately 20% at one year of age. In the brain, which showed the highest expression in cerebral cortical and hippocampal neurons, the proportion of NSDHL negative cells also dropped dramatically over the first year of life. Our results suggest that while NSDHL-deficient cells in the mosaic Bpa(1H) female are able to survive and differentiate during embryonic development, they are subject to negative selection over the life of the animal.
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Affiliation(s)
- David Cunningham
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA.
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Differential roles of Trk and p75 neurotrophin receptors in tumorigenesis and chemoresistance ex vivo and in vivo. Cancer Chemother Pharmacol 2009; 65:1047-56. [PMID: 19701634 DOI: 10.1007/s00280-009-1110-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 08/05/2009] [Indexed: 11/27/2022]
Abstract
The neurotrophin receptors TrkA (NGF receptor) and TrkC (NT-3 receptor) have been shown to be important in staging disease and predicting progression and drug response for various neoplasias such as neuroblastoma, medulloblastoma and prostate cancer. Less is known about the role of the p75 neurotrophin receptor in cancer, but it influences metastatic potential in glioblastoma. To determine the effect of each neurotrophin receptor or co-receptor expression in tumorigenesis, we examined PC12 pheochromocytomas. PC12 wild type (TrkA(+), p75(++)) were compared to three PC12-derived cell lines expressing varying levels of TrkA or TrkC and/or p75. Growth rates, tumorigenic potential ex vivo and in vivo, and chemotherapeutic drug response profiles differed depending on the neurotrophin receptor phenotype. The ability of neurotrophins to rescue cells from doxorubicin or cisplatin induced cell death also varied depending on phenotype. Thus, unique neurotrophin receptor tumor profiles may determine tumor aggressiveness and chemoresistance. This work may help to develop tailored therapies for specific tumor phenotypes by combining traditional chemotherapy with neurotrophin receptor modulators.
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Korade Z, Kenworthy AK, Mirnics K. Molecular consequences of altered neuronal cholesterol biosynthesis. J Neurosci Res 2009; 87:866-75. [PMID: 18951487 DOI: 10.1002/jnr.21917] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The first dedicated step in de novo cholesterol biosynthesis begins with formation of squalene and ends with the reduction of 7-dehydrocholesterol by 7-dehydrocholesterol reductase (Dhcr7) into cholesterol, which is an essential structural and signaling molecule. Mutations in the Dhcr7 gene lead to Smith-Lemli-Opitz syndrome (SLOS), which is characterized by developmental deformities, incomplete myelination, and mental retardation. To understand better the molecular consequences of Dhcr7 deficiency in neuronal tissue, we analyzed the effect of cholesterol deficiency on the transcriptome in Neuro2a cells. Transient down-regulation of Dhcr7 by siRNA led to altered expression of multiple molecules that play critical roles in intracellular signaling or vesicular transport or are inserted into membrane rafts (e.g. Egr1, Snx, and Adam19). A similar down-regulation was also observed in stable Dhrc7-shRNA-transfected cell lines, and the findings were verified by qPCR. Furthermore, we investigated the Dhcr7-deficient and control cells for the expression of several critical genes involved in lipid biosynthesis. Among these, fatty acid synthase, sterol-regulatory element binding protein 2, SREBF chaperone, site-1 protease, and squalene synthase showed a significant down-regulation, suggesting that, in a neuronal cell line, Dhcr7 is a potent regulator of lipid biosynthesis. Importantly, the gene expression changes were present in both lipid-containing and cholesterol-deficient media, suggesting that intrinsic cholesterol biosynthesis is necessary for normal neuronal function and cannot be supplemented from extrinsic sources.
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Affiliation(s)
- Zeljka Korade
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, USA.
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Nieweg K, Schaller H, Pfrieger FW. Marked differences in cholesterol synthesis between neurons and glial cells from postnatal rats. J Neurochem 2009; 109:125-34. [DOI: 10.1111/j.1471-4159.2009.05917.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Korade Z, Kenchappa RS, Mirnics K, Carter BD. NRIF is a regulator of neuronal cholesterol biosynthesis genes. J Mol Neurosci 2008; 38:152-8. [PMID: 18677445 DOI: 10.1007/s12031-008-9136-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Accepted: 07/09/2008] [Indexed: 11/30/2022]
Abstract
Cholesterol is a critical component of neuronal membranes, required for normal signal transduction. We showed previously that adult hippocampal neurons co-express high levels of cholesterogenic enzymes, and that their expression is under the control of the p75 neurotrophin receptor (p75NTR). Most of the cellular effects of p75NTR are mediated via interacting proteins, including neurotrophin receptor interacting factor (NRIF). In this study, we tested the hypothesis that p75NTR-dependent regulation of cholesterol and lipid biosynthesis genes is mediated by NRIF. We found that in vitro down regulation of NRIF expression decreased the mRNA for two main cholesterogenic enzymes, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (Hmgcr; EC 2.3.3.10) and 7-dehydrocholesterol reductase (Dhcr7; EC 1.3.1.21). Further analyses revealed that NRIF-dependent and Dhcr7-dependent transcriptional changes show a high degree of overlap, and that NRIF reduction resulted in reduced expression of sterol-sensing domain protein SCAP, followed by a decrease in mRNA levels of SRE-motif containing genes (HMGCR, FASN, SREBP2, S1P, and SQS1). Finally, a reduction in cholesterol biosynthesis-related gene expression was also observed in hippocampal tissue of mice with NRIF deletion. Our combined in vitro and in vivo studies suggest that hippocampal neuronal cholesterol biosynthesis is regulated through the p75NTR interacting factor NRIF.
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Affiliation(s)
- Zeljka Korade
- Department of Biochemistry, Vanderbilt University School of Medicine, 8124A MRB III, Nashville, TN 37232, USA.
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Korade Z, Kenworthy AK. Lipid rafts, cholesterol, and the brain. Neuropharmacology 2008; 55:1265-73. [PMID: 18402986 DOI: 10.1016/j.neuropharm.2008.02.019] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 02/15/2008] [Accepted: 02/26/2008] [Indexed: 01/11/2023]
Abstract
Lipid rafts are specialized membrane microdomains that serve as organizing centers for assembly of signaling molecules, influence membrane fluidity and trafficking of membrane proteins, and regulate different cellular processes such as neurotransmission and receptor trafficking. In this article, we provide an overview of current methods for studying lipid rafts and models for how lipid rafts might form and function. Next, we propose a potential mechanism for regulating lipid rafts in the brain via local control of cholesterol biosynthesis by neurotrophins and their receptors. Finally, we discuss evidence that altered cholesterol metabolism and/or lipid rafts play a critical role in the pathophysiology of multiple CNS disorders, including Smith-Lemli-Opitz syndrome, Huntington's, Alzheimer's, and Niemann-Pick Type C diseases.
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Affiliation(s)
- Zeljka Korade
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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