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Dragano NR, Monfort-Pires M, Velloso LA. Mechanisms Mediating the Actions of Fatty Acids in the Hypothalamus. Neuroscience 2020; 447:15-27. [DOI: 10.1016/j.neuroscience.2019.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 10/02/2019] [Accepted: 10/03/2019] [Indexed: 12/12/2022]
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Xicoy H, Brouwers JF, Wieringa B, Martens GJM. Explorative Combined Lipid and Transcriptomic Profiling of Substantia Nigra and Putamen in Parkinson's Disease. Cells 2020; 9:E1966. [PMID: 32858884 DOI: 10.3390/cells9091966] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 12/19/2022] Open
Abstract
Parkinson’s disease (PD) is characterized by the loss of dopaminergic neurons from the substantia nigra (SN) that project to the dorsal striatum (caudate-putamen). To better understand the molecular mechanisms underlying PD, we performed combined lipid profiling and RNA sequencing of SN and putamen samples from PD patients and age-matched controls. SN lipid analysis pointed to a neuroinflammatory component and included elevated levels of the endosomal lipid Bis (Monoacylglycero)Phosphate 42:8, while two of the three depleted putamen lipids were saturated sphingomyelin species. Remarkably, we observed gender-related differences in the SN and putamen lipid profiles. Transcriptome analysis revealed that the top-enriched pathways among the 354 differentially expressed genes (DEGs) in the SN were “protein folding” and “neurotransmitter transport”, and among the 261 DEGs from putamen “synapse organization”. Furthermore, we identified pathways, e.g., “glutamate signaling”, and genes, encoding, e.g., an angiotensin receptor subtype or a proprotein convertase, that have not been previously linked to PD. The identification of 33 genes that were common among the SN and putamen DEGs, which included the α-synuclein paralog β-synuclein, may contribute to the understanding of general PD mechanisms. Thus, our proof-of-concept data highlights new genes, pathways and lipids that have not been explored before in the context of PD.
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Marin R, Diaz M. Estrogen Interactions With Lipid Rafts Related to Neuroprotection. Impact of Brain Ageing and Menopause. Front Neurosci 2018; 12:128. [PMID: 29559883 PMCID: PMC5845729 DOI: 10.3389/fnins.2018.00128] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 02/16/2018] [Indexed: 12/22/2022] Open
Abstract
Estrogens (E2) exert a plethora of neuroprotective actions against aged-associated brain diseases, including Alzheimer's disease (AD). Part of these actions takes place through binding to estrogen receptors (ER) embedded in signalosomes, where numerous signaling proteins are clustered. Signalosomes are preferentially located in lipid rafts which are dynamic membrane microstructures characterized by a peculiar lipid composition enriched in gangliosides, saturated fatty acids, cholesterol, and sphingolipids. Rapid E2 interactions with ER-related signalosomes appear to trigger intracellular signaling ultimately leading to the activation of molecular mechanisms against AD. We have previously observed that the reduction of E2 blood levels occurring during menopause induced disruption of ER-signalosomes at frontal cortical brain areas. These molecular changes may reduce neuronal protection activities, as similar ER signalosome derangements were observed in AD brains. The molecular impairments may be associated with changes in the lipid composition of lipid rafts observed in neurons during menopause and AD. These evidences indicate that the changes in lipid raft structure during aging may be at the basis of alterations in the activity of ER and other neuroprotective proteins integrated in these membrane microstructures. Moreover, E2 is a homeostatic modulator of lipid rafts. Recent work has pointed to this relevant aspect of E2 activity to preserve brain integrity, through mechanisms affecting lipid uptake and local biosynthesis in the brain. Some evidences have demonstrated that estrogens and the docosahexaenoic acid (DHA) exert synergistic effects to stabilize brain lipid matrix. DHA is essential to enhance molecular fluidity at the plasma membrane, promoting functional macromolecular interactions in signaling platforms. In support of this, DHA detriment in neuronal lipid rafts has been associated with the most common age-associated neuropathologies, namely AD and Parkinson disease. Altogether, these findings indicate that E2 may participate in brain preservation through a dual membrane-related mechanism. On the one hand, E2 interacting with ER related signalosomes may protect against neurotoxic insults. On the other hand, E2 may exert lipostatic actions to preserve lipid balance in neuronal membrane microdomains. The different aspects of the emerging multifunctional role of estrogens in membrane-related signalosomes will be discussed in this review.
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Affiliation(s)
- Raquel Marin
- Laboratory of Cellular Neurobiology, Department of Basic Medical Sciences, Medicine, Faculty of Health Sciences, University of La Laguna, Tenerife, Spain.,Fisiología y Biofísica de la Membrana Celular en Patologías Neurodegenerativas y Tumorales, Consejo Superior de Investigaciones Cientificas, Unidad Asociada de Investigación, Universidad de La Laguna Tenerife, Tenerife, Spain
| | - Mario Diaz
- Fisiología y Biofísica de la Membrana Celular en Patologías Neurodegenerativas y Tumorales, Consejo Superior de Investigaciones Cientificas, Unidad Asociada de Investigación, Universidad de La Laguna Tenerife, Tenerife, Spain.,Laboratory of Membrane Physiology and Biophysics, Department of Animal Biology, Edaphology and Geology, University of La Laguna, Tenerife, Spain
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Colangelo LA, Ouyang P, Golden SH, Szklo M, Gapstur SM, Vaidya D, Liu K. Do sex hormones or hormone therapy modify the relation of n-3 fatty acids with incident depressive symptoms in postmenopausal women? The MESA Study. Psychoneuroendocrinology 2017; 75:26-35. [PMID: 27768981 PMCID: PMC5135581 DOI: 10.1016/j.psyneuen.2016.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 09/04/2016] [Accepted: 10/11/2016] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Considering that estradiol (E2) and n-3 polyunsaturated fatty acids (PUFAs) have roles in neurogenesis and in neurotransmission, we examined whether the association of PUFAs with incident depressive symptoms in postmenopausal women is modified by hormone therapy (HT) use or estrogen status. METHODS Women (N=1616) free of depressive symptoms at baseline (2000-2002) in the Multi-Ethnic Study of Atherosclerosis were classified by HT usage and quartiles of dietary eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and the sum EPA+DHA. Women with serum E2 ≤0.073 nmol/L (sample median), were classified low on E2. Poisson regression was used to model incident depressive symptoms at examination 3 (2004-05), defined by the Center for Epidemiological Studies Depression Scale ≥16 or taking an antidepressant, first as a function of HT use and n-3 PUFA quartiles, and second, as a function of low E2 status and n-3 PUFA quartiles. RESULTS Among HT non- users, positive, graded relationships (p-trends≤0.003) were found between PUFAs and incident depressive symptoms. Compared to the lowest quartile, the adjusted risk ratios (RRs) for the highest were 2.10, 2.39, and 2.04 for EPA, DHA, and EPA+DHA, respectively. For HT users, no associations were seen. When analyses were run for E2 status, the RRs over quartiles of the PUFAs were positive and graded for low E2 women, but were null for High E2 women. CONCLUSIONS Higher intakes of DHA and EPA were associated with higher risk of depressive symptoms in nonusers of HT, contrary to hypothesis.
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Affiliation(s)
- Laura A Colangelo
- Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, 680 North Lake Shore Drive, Suite 1400, Chicago, IL 60611, United States.
| | - Pamela Ouyang
- Department of Medicine, Johns Hopkins University, Baltimore,
Maryland
| | | | - Moyses Szklo
- Department of Epidemiology, Johns Hopkins University, Baltimore,
Maryland
| | - Susan M Gapstur
- Epidemiology Research Program, American Cancer Society, Atlanta,
Georgia
| | - Dhananjay Vaidya
- Department of Medicine, Johns Hopkins University, Baltimore,
Maryland
| | - Kiang Liu
- Department of Preventive Medicine, Feinberg School of Medicine,
Northwestern University, 680 North Lake Shore Drive, Suite 1400, Chicago, Illinois
60611
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Díaz M, Fabelo N, Casañas-Sánchez V, Marin R, Gómez T, Quinto-Alemany D, Pérez JA. Hippocampal Lipid Homeostasis in APP/PS1 Mice is Modulated by a Complex Interplay Between Dietary DHA and Estrogens: Relevance for Alzheimer's Disease. J Alzheimers Dis 2016; 49:459-81. [PMID: 26519437 DOI: 10.3233/jad-150470] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Current evidence suggests that lipid homeostasis in the hippocampus is affected by different genetic, dietary, and hormonal factors, and that its deregulation may be associated with the onset and progression of Alzheimer's disease (AD). However, the precise levels of influence of each of these factors and their potential interactions remain largely unknown, particularly during neurodegenerative processes. In the present study, we have performed multifactorial analyses of the combined effects of diets containing different doses of docosahexaenoic acid (DHA), estrogen status (ovariectomized animals receiving vehicle or 17β-estradiol), and genotype (wild-type or transgenic APP/PS1 mice) in hippocampal lipid profiles. We have observed that the three factors affect lipid classes and fatty acid composition to different extents, and that strong interactions between these factors exist. The most aberrant lipid profiles were observed in APP/PS1 animals receiving DHA-poor diets and deprived of estrogens. Conversely, wild-type animals under a high-DHA diet and receiving estradiol exhibited a lipid profile that closely resembled that of the hippocampus of control animals. Interestingly, though the lipid signatures of APP/PS1 hippocampi markedly differed from wild-type, administration of a high-DHA diet in the presence of estrogens gave rise to a lipid profile that approached that of control animals. Paralleling changes in lipid composition, patterns of gene expression of enzymes involved in lipid biosynthesis were also altered and affected by combination of experimental factors. Overall, these results indicate that hippocampal lipid homeostasis is strongly affected by hormonal and dietary conditions, and that manipulation of these factors might be incorporated in AD therapeutics.
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Affiliation(s)
- Mario Díaz
- Department of Animal Physiology, Laboratory of Membrane Physiology and Biophysics, University of La Laguna, Tenerife, Spain
| | - Noemí Fabelo
- Department of Animal Physiology, Laboratory of Membrane Physiology and Biophysics, University of La Laguna, Tenerife, Spain
| | | | - Raquel Marin
- Department of Physiology, Laboratory of Cellular Neurobiology, University of La Laguna, Tenerife, Spain
| | - Tomás Gómez
- Department of Animal Physiology, Laboratory of Membrane Physiology and Biophysics, University of La Laguna, Tenerife, Spain
| | - David Quinto-Alemany
- Department of Animal Physiology, Laboratory of Membrane Physiology and Biophysics, University of La Laguna, Tenerife, Spain
| | - José A Pérez
- Department of Genetics, University of La Laguna, Tenerife, Spain
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Maselli A, Pierdominici M, Vitale C, Ortona E. Membrane lipid rafts and estrogenic signalling: a functional role in the modulation of cell homeostasis. Apoptosis 2015; 20:671-8. [PMID: 25637184 DOI: 10.1007/s10495-015-1093-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
It has become widely accepted that along with their ability to directly regulate gene expression, estrogens also influence cell signalling and cell function via rapid membrane-initiated events. Many of these signalling processes are dependent on estrogen receptors (ER) localized to the plasma membrane. However, the mechanisms by which ER are able to trigger cell signalling when targeted to the membrane surface have to be determined yet. Lipid rafts seem to be essential for the plasma membrane localization of ER and play a critical role in their membrane-initiated effects. In this review, we briefly recapitulate the localization and function of ER in different cell types and mostly discuss the possible role of lipid rafts in this context. Further studies in this field may disclose new promising therapeutic avenues by the disruption of lipid rafts in those diseases in which membrane ER activation has been demonstrated to play a pathogenetic role.
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Affiliation(s)
- Angela Maselli
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
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Fabelo N, Martín V, Marín R, Moreno D, Ferrer I, Díaz M. Altered lipid composition in cortical lipid rafts occurs at early stages of sporadic Alzheimer's disease and facilitates APP/BACE1 interactions. Neurobiol Aging 2014; 35:1801-12. [DOI: 10.1016/j.neurobiolaging.2014.02.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 01/18/2014] [Accepted: 02/05/2014] [Indexed: 12/31/2022]
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Fernández-Pérez L, Santana-Farré R, de Mirecki-Garrido M, García I, Guerra B, Mateo-Díaz C, Iglesias-Gato D, Díaz-Chico JC, Flores-Morales A, Díaz M. Lipid profiling and transcriptomic analysis reveals a functional interplay between estradiol and growth hormone in liver. PLoS One 2014; 9:e96305. [PMID: 24816529 PMCID: PMC4015979 DOI: 10.1371/journal.pone.0096305] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 04/05/2014] [Indexed: 01/21/2023] Open
Abstract
17β-estradiol (E2) may interfere with endocrine, metabolic, and gender-differentiated functions in liver in both females and males. Indirect mechanisms play a crucial role because of the E2 influence on the pituitary GH secretion and the GHR-JAK2-STAT5 signaling pathway in the target tissues. E2, through its interaction with the estrogen receptor, exerts direct effects on liver. Hypothyroidism also affects endocrine and metabolic functions of the liver, rendering a metabolic phenotype with features that mimic deficiencies in E2 or GH. In this work, we combined the lipid and transcriptomic analysis to obtain comprehensive information on the molecular mechanisms of E2 effects, alone and in combination with GH, to regulate liver functions in males. We used the adult hypothyroid-orchidectomized rat model to minimize the influence of internal hormones on E2 treatment and to explore its role in male-differentiated functions. E2 influenced genes involved in metabolism of lipids and endo-xenobiotics, and the GH-regulated endocrine, metabolic, immune, and male-specific responses. E2 induced a female-pattern of gene expression and inhibited GH-regulated STAT5b targeted genes. E2 did not prevent the inhibitory effects of GH on urea and amino acid metabolism-related genes. The combination of E2 and GH decreased transcriptional immune responses. E2 decreased the hepatic content of saturated fatty acids and induced a transcriptional program that seems to be mediated by the activation of PPARα. In contrast, GH inhibited fatty acid oxidation. Both E2 and GH replacements reduced hepatic CHO levels and increased the formation of cholesterol esters and triacylglycerols. Notably, the hepatic lipid profiles were endowed with singular fingerprints that may be used to segregate the effects of different hormonal replacements. In summary, we provide in vivo evidence that E2 has a significant impact on lipid content and transcriptome in male liver and that E2 exerts a marked influence on GH physiology, with implications in human therapy.
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Affiliation(s)
- Leandro Fernández-Pérez
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
- * E-mail:
| | - Ruymán Santana-Farré
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
| | - Mercedes de Mirecki-Garrido
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
| | - Irma García
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
- Department of Animal Biology, University of La Laguna, Laboratory of Membrane Physiology and Biophysics, La Laguna, Spain
| | - Borja Guerra
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Carlos Mateo-Díaz
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Diego Iglesias-Gato
- Molecular Endocrinology group, University of Copenhagen - Novo Nordisk Center for Protein Research, Copenhagen, Denmark
| | - Juan Carlos Díaz-Chico
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria - Biomedical and Health Research Institute (IUIBS), Molecular and Translational Endocrinology Group, Las Palmas de Gran Canaria, Spain
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Amilcar Flores-Morales
- Molecular Endocrinology group, University of Copenhagen - Novo Nordisk Center for Protein Research, Copenhagen, Denmark
| | - Mario Díaz
- Cancer Research Institute of The Canary Islands (ICIC), Las Palmas de Gran Canaria, Canary Islands, Spain
- Department of Animal Biology, University of La Laguna, Laboratory of Membrane Physiology and Biophysics, La Laguna, Spain
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Sibbons CM, Brenna JT, Lawrence P, Hoile SP, Clarke-Harris R, Lillycrop KA, Burdge GC. Effect of sex hormones on n-3 polyunsaturated fatty acid biosynthesis in HepG2 cells and in human primary hepatocytes. Prostaglandins Leukot Essent Fatty Acids 2014; 90:47-54. [PMID: 24411721 PMCID: PMC4046896 DOI: 10.1016/j.plefa.2013.12.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 01/25/2023]
Abstract
Female humans and rodents have been shown to have higher 22:6n-3 status and synthesis than males. It is unclear which sex hormone is involved. We investigated the specificity of the effects of physiological concentrations of sex hormones in vitro on the mRNA expression of genes involved in polyunsaturated fatty acid (PUFA) biosynthesis and on the conversion of [d5]-18:3n-3 to longer chain fatty acids. Progesterone, but not 17α-ethynylestradiol or testosterone, increased FADS2, FADS1, ELOVl 5 and ELOVl 2 mRNA expression in HepG2 cells, but only FADS2 in primary human hepatocytes. In HepG2 cells, these changes were accompanied by hypomethylation of specific CpG loci in the FADS2 promoter. Progesterone, not 17α-ethynylestradiol or testosterone, increased conversion of [d5]-18:3n-3 to 20:5n-3, 22:5n-3 and 22:6n-3. These findings show that progesterone increases n-3 PUFA biosynthesis by up-regulating the mRNA expression of genes involved in this pathway, possibly via changes in the epigenetic regulation of FADS2.
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Affiliation(s)
- Charlene M Sibbons
- Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - J Thomas Brenna
- Division of Nutritional Sciences, Cornell University, Ithaca, New York, United States
| | - Peter Lawrence
- Division of Nutritional Sciences, Cornell University, Ithaca, New York, United States
| | - Samuel P Hoile
- Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Rebecca Clarke-Harris
- Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Karen A Lillycrop
- Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
| | - Graham C Burdge
- Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK.
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Marin R, Casañas V, Pérez JA, Fabelo N, Fernandez CE, Diaz M. Oestrogens as modulators of neuronal signalosomes and brain lipid homeostasis related to protection against neurodegeneration. J Neuroendocrinol 2013; 25:1104-15. [PMID: 23795744 DOI: 10.1111/jne.12068] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/22/2013] [Accepted: 06/18/2013] [Indexed: 12/19/2022]
Abstract
Oestrogens trigger several pathways at the plasma membrane that exert beneficial actions against neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. Part of these actions takes place in lipid rafts, which are membrane domains with a singular protein and lipid composition. These microdomains also represent a preferential site for signalling protein complexes, or signalosomes. A plausible hypothesis is that the dynamic interaction of signalosomes with different extracellular ligands may be at the basis of neuronal maintenance against different neuropathologies. Oestrogen receptors are localised in neuronal lipid rafts, taking part of macromolecular complexes together with a voltage-dependent anion channel (VDAC), and other molecules. Oestradiol binding to its receptor at this level enhances neuroprotection against amyloid-β degeneration through the activation of different signal transduction pathways, including VDAC gating modulation. Moreover, part of the stability and functionality of signalling platforms lays on the distribution of lipid hallmarks in these microstructures, which modulate membrane physicochemical properties, thus favouring molecular interactions. Interestingly, recent findings indicate a potential role of oestrogens in the preservation of neuronal membrane physiology related to lipid homeostasis. Thus, oestrogens and docosahexaenoic acid may act synergistically to stabilise brain lipid structure by regulating neuronal lipid biosynthetic pathways, suggesting that part of the neuroprotective effects elicited by oestrogens occur through mechanisms aimed at preserving lipid homeostasis. Overall, oestrogen mechanisms of neuroprotection may occur not only by its interaction with neuronal protein targets through nongenomic and genomic mechanisms, but also through its participation in membrane architecture stabilisation via 'lipostatic' mechanisms.
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Affiliation(s)
- R Marin
- Department of Physiology, Laboratory of Cellular Neurobiology, University of La Laguna, La Laguna, Tenerife, Spain
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Abstract
Alterations in the lipid composition of lipid rafts have been demonstrated both in human brain and transgenic mouse models, and it has been postulated that aberrant lipid composition in lipid rafts is partly responsible for neuronal degeneration. In order to assess the impact of lipid changes on lipid raft functional properties, we have aimed at determining relevant physicochemical modifications in lipid rafts purified from frontal cortex of wild type (WT) and APP/PS1 double transgenic mice. By means of steady-state fluorescence anisotropy analyses using two lipid soluble fluorescent probes, TMA-DPH (1-[(4-trimethyl-amino)phenyl]-6-phenyl-1,3,5-hexatriene) and DPH (1,6-diphenyl-1,3,5-hexatriene), we demonstrate that cortical lipid rafts from WT and APP/PS1 animals exhibit different biophysical behaviors, depending on genotype but also on age. Thus, aged APP/PS1 animals exhibited slightly more liquid-ordered lipid rafts than WT counterparts. Membrane microviscosity ηapp analyses demonstrate that WT lipid rafts are more fluid than APP/PS1 animals of similar age, both at the aqueous interface and hydrophobic core of the membrane. ηapp in APP/PS1 animals was higher for DPH than for TMA-DPH under similar experimental conditions, indicating that the internal core of the membrane is more viscous than the raft membrane at the aqueous interface. The most dramatic changes in biophysical properties of lipid rafts were observed when membrane cholesterol was depleted with methyl-β-cyclodextrin. Overall, our results indicate that APP/PS1 genotype strongly affects physicochemical properties of lipid raft. Such alterations appear not to be homogeneous across the raft membrane axis, but rather are more prominent at the membrane plane. These changes correlate with aberrant proportions of sphingomyelin, cholesterol, and saturated fatty acids, as well as polyunsaturated fatty acids, measured in lipid rafts from frontal cortex in this familial model of Alzheimer's Disease.
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Affiliation(s)
- Mario L Diaz
- Laboratorio de Fisiología y Biofísica de Membranas, Departamento de Biología Animal Facultad de Biología, Universidad de La Laguna Tenerife, Spain
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