1
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Haddadi M, Haghi M, Rezaei N, Kiani Z, Akkülah T, Celik A. APOE and Alzheimer's disease: Pathologic clues from transgenic Drosophila melanogaster. Arch Gerontol Geriatr 2024; 123:105420. [PMID: 38537387 DOI: 10.1016/j.archger.2024.105420] [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: 12/19/2023] [Revised: 02/03/2024] [Accepted: 03/19/2024] [Indexed: 06/06/2024]
Abstract
Alzheimer's disease (AD) is one of the most common forms of neurodegenerative diseases. Apolipoprotein E4 (ApoE4) is the main genetic risk factor in the development of late-onset AD. However, the exact mechanism underlying ApoE4-mediated neurodegeneration remains unclear. We utilized Drosophila melanogaster to examine the neurotoxic effects of various human APOE isoforms when expressed specifically in glial and neural cells. We assessed impacts on mitochondrial dynamics, ER stress, lipid metabolism, and bio-metal ion concentrations in the central nervous system (CNS) of the transgenic flies. Dachshund antibody staining revealed a reduction in the number of Kenyon cells. Behavioral investigations including ethanol tolerance and learning and memory performance demonstrated neuronal dysfunction in APOE4-expressing larvae and adult flies. Transcription level of marf and drp-1 were found to be elevated in APOE4 flies, while atf4, atf6, and xbp-1 s showed down regulation. Enhanced concentrations of triglyceride and cholesterol in the CNS were observed in APOE4 transgenic flies, with especially pronounced effects upon glial-specific expression of the gene. Spectrophotometry of brain homogenate revealed enhanced Fe++ and Zn++ ion levels in conjunction with diminished Cu++ levels upon APOE4 expression. To explore therapeutic strategies, we subjected the flies to heat-shock treatment, aiming to activate heat-shock proteins (HSPs) and assess their potential to mitigate the neurotoxic effects of APOE isoforms. The results showed potential therapeutic benefits for APOE4-expressing flies, hinting at an ability to attenuate memory deterioration. Overall, our findings suggest that APOE4 can alter lipid metabolism, bio metal ion homeostasis, and disrupt the harmonious fission-fusion balance of neuronal and glial mitochondria, ultimately inducing ER stress. These alterations mirror the main clinical manifestations of AD in patients. Therefore, our work underscores the suitability of Drosophila as a fertile model for probing the pathological roles of APOE and furthering our understanding of diverse isoform-specific functions.
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Affiliation(s)
- Mohammad Haddadi
- Department of Biology, Faculty of Basic Sciences, University of Zabol, Zabol, Iran; Genetics and Non-communicable Diseases Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
| | - Mehrnaz Haghi
- Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran
| | - Niloofar Rezaei
- Department of Biology, Faculty of Basic Sciences, University of Zabol, Zabol, Iran
| | - Zahra Kiani
- Department of Biology, Faculty of Basic Sciences, University of Zabol, Zabol, Iran
| | - Taha Akkülah
- Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkiye; Center for Life Sciences and Technologies, Bogazici University, Istanbul, Turkiye
| | - Arzu Celik
- Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkiye; Center for Life Sciences and Technologies, Bogazici University, Istanbul, Turkiye
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2
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Staršíchová A. SR-B1-/-ApoE-R61h/h Mice Mimic Human Coronary Heart Disease. Cardiovasc Drugs Ther 2023:10.1007/s10557-023-07475-8. [PMID: 37273155 DOI: 10.1007/s10557-023-07475-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/22/2023] [Indexed: 06/06/2023]
Abstract
Cardiovascular diseases are the leading cause of death in the modern world. Atherosclerosis underlies the majority of these pathologies and may result in sudden life-threatening events such as myocardial infarction or stroke. Current concepts consider a rupture (resp. erosion) of "unstable/vulnerable" atherosclerotic plaques as a primary cause leading to thrombus formation and subsequent occlusion of the artery lumen finally triggering an acute clinical event. We and others described SR-B1-/-ApoE-R61h/h mice mimicking clinical coronary heart disease in all major aspects: from coronary atherosclerosis through vulnerable plaque ruptures leading to thrombus formation/coronary artery occlusion, finally resulting in myocardial infarction/ischemia. SR-B1-/-ApoE-R61h/h mouse provides a valuable model to study vulnerable/occlusive plaques, to evaluate bioactive compounds as well as new anti-inflammatory and "anti-rupture" drugs, and to test new technologies in experimental cardiovascular medicine. This review summarizes and discuss our knowledge about SR-B1-/-ApoE-R61h/h mouse model based on recent publications and experimental observations from the lab.
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Affiliation(s)
- Andrea Staršíchová
- Graduate School Cell Dynamics and Disease, University of Muenster, Muenster, Germany.
- European Institute for Molecular Imaging, University of Muenster, Muenster, Germany.
- Novogenia Covid GmbH, Eugendorf, Austria.
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3
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Sergi D, Zauli E, Tisato V, Secchiero P, Zauli G, Cervellati C. Lipids at the Nexus between Cerebrovascular Disease and Vascular Dementia: The Impact of HDL-Cholesterol and Ceramides. Int J Mol Sci 2023; 24:ijms24054403. [PMID: 36901834 PMCID: PMC10002119 DOI: 10.3390/ijms24054403] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 02/20/2023] [Indexed: 02/25/2023] Open
Abstract
Cerebrovascular diseases and the subsequent brain hypoperfusion are at the basis of vascular dementia. Dyslipidemia, marked by an increase in circulating levels of triglycerides and LDL-cholesterol and a parallel decrease in HDL-cholesterol, in turn, is pivotal in promoting atherosclerosis which represents a common feature of cardiovascular and cerebrovascular diseases. In this regard, HDL-cholesterol has traditionally been considered as being protective from a cardiovascular and a cerebrovascular prospective. However, emerging evidence suggests that their quality and functionality play a more prominent role than their circulating levels in shaping cardiovascular health and possibly cognitive function. Furthermore, the quality of lipids embedded in circulating lipoproteins represents another key discriminant in modulating cardiovascular disease, with ceramides being proposed as a novel risk factor for atherosclerosis. This review highlights the role of HDL lipoprotein and ceramides in cerebrovascular diseases and the repercussion on vascular dementia. Additionally, the manuscript provides an up-to-date picture of the impact of saturated and omega-3 fatty acids on HDL circulating levels, functionality and ceramide metabolism.
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Affiliation(s)
- Domenico Sergi
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
- Correspondence:
| | - Enrico Zauli
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Veronica Tisato
- Department of Translational Medicine and LTTA Centre, University of Ferrara, 44121 Ferrara, Italy
| | - Paola Secchiero
- Department of Translational Medicine and LTTA Centre, University of Ferrara, 44121 Ferrara, Italy
| | - Giorgio Zauli
- King Khaled Eye Specialistic Hospital, Riyadh 11462, Saudi Arabia
| | - Carlo Cervellati
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
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4
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Koller EJ, Gonzalez De La Cruz E, Weinrich M, Williams T, Cruz PE, Ryu D, Golde TE, Sullivan PM, Lewis J, Borchelt DR, Chakrabarty P. Intracerebral Expression of AAV-APOE4 Is Not Sufficient to Alter Tau Burden in Two Distinct Models of Tauopathy. Mol Neurobiol 2020; 57:1986-2001. [PMID: 31903524 DOI: 10.1007/s12035-019-01859-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 12/15/2019] [Indexed: 12/14/2022]
Abstract
Apolipoprotein E4 (APOE4) is the major genetic risk factor for sporadic Alzheimer's disease (AD), which is characterized by amyloid β (Aβ) plaques and tau tangles. Though the role of APOE4 in Aβ pathogenesis has been mechanistically defined in rodent models, much less is known regarding the relationship of APOE4 to tau pathogenesis. Recent studies have indicated a possible correlation between APOE isoform-dependent alterations in tau pathology and neurodegeneration. To explore whether neuronal expression of APOE4 triggers tauopathy, here we delivered adeno-associated viruses (AAV) expressing human APOE4 in two different models of tauopathy-rTg4510 and PS19 lines. Intracerebroventricular delivery of AAV-APOE4 in neonatal rTg4510 and PS19 mice resulted in increased APOE4 protein in neurons but did not result in altered phosphorylated tau burden, pretangle tau pathology, or silver-positive tangle pathology. Biochemical analysis of synaptic proteins did not reveal substantial alterations. Our results indicate that over-expression of APOE4 in neurons, using an AAV-mediated approache, is not sufficient to accelerate or otherwise alter the inherent tau pathology that occurs in mice overexpressing mutant human tau.
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Affiliation(s)
- Emily J Koller
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | - Elsa Gonzalez De La Cruz
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | - Mary Weinrich
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | - Tosha Williams
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | - Pedro E Cruz
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | - Daniel Ryu
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | - Todd E Golde
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.,McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Patrick M Sullivan
- Department of Medicine, Duke University, Durham VA Geriatric Research, Education and Clinical Center, Durham, NC, 27710, USA
| | - Jada Lewis
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.,McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA
| | - David R Borchelt
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA.,McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Paramita Chakrabarty
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA. .,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA. .,McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA.
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Zhu F, Nair RR, Fisher EMC, Cunningham TJ. Humanising the mouse genome piece by piece. Nat Commun 2019; 10:1845. [PMID: 31015419 PMCID: PMC6478830 DOI: 10.1038/s41467-019-09716-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/23/2019] [Indexed: 12/14/2022] Open
Abstract
To better understand human health and disease, researchers create a wide variety of mouse models that carry human DNA. With recent advances in genome engineering, the targeted replacement of mouse genomic regions with orthologous human sequences has become increasingly viable, ranging from finely tuned humanisation of individual nucleotides and amino acids to the incorporation of many megabases of human DNA. Here, we examine emerging technologies for targeted genomic humanisation, we review the spectrum of existing genomically humanised mouse models and the insights such models have provided, and consider the lessons learned for designing such models in the future. Generation of transgenic mice has become routine in studying gene function and disease mechanisms, but often this is not enough to fully understand human biology. Here, the authors review the current state of the art of targeted genomic humanisation strategies and their advantages over classic approaches.
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Affiliation(s)
- Fei Zhu
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Remya R Nair
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Elizabeth M C Fisher
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK.
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6
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Progranulin in the hematopoietic compartment protects mice from atherosclerosis. Atherosclerosis 2018; 277:145-154. [PMID: 30212683 DOI: 10.1016/j.atherosclerosis.2018.08.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 08/15/2018] [Accepted: 08/29/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND AND AIMS Progranulin is a circulating protein that modulates inflammation and is found in atherosclerotic lesions. Here we determined whether inflammatory cell-derived progranulin impacts atherosclerosis development. METHODS Ldlr-/- mice were transplanted with bone marrow from wild-type (WT) or Grn-/- (progranulin KO) mice (referred to as Tx-WT and Tx-KO, respectively). RESULTS After 10 weeks of high-fat diet feeding, both groups displayed similarly elevated plasma levels of cholesterol and triglycerides. Despite abundant circulating levels of progranulin, the size of atherosclerotic lesions in Tx-KO mice was increased by 47% in aortic roots and by 62% in whole aortas. Aortic root lesions in Tx-KO mice had increased macrophage content and larger necrotic cores, consistent with more advanced lesions. Progranulin staining was markedly reduced in the lesions of Tx-KO mice, indicating little or no uptake of circulating progranulin. Mechanistically, cultured progranulin-deficient macrophages exhibited increased lysosome-mediated exophagy of aggregated low-density lipoproteins resulting in increased cholesterol uptake and foam cell formation. CONCLUSIONS We conclude that hematopoietic progranulin deficiency promotes diet-induced atherosclerosis in Ldlr-/- mice, possibly due to increased exophagy-mediated cholesterol uptake. Circulating progranulin was unable to prevent the increased lesion development, consistent with the importance of progranulin acting via cell-autonomous or local effects.
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7
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Apolipoprotein E and Atherosclerosis: From Lipoprotein Metabolism to MicroRNA Control of Inflammation. J Cardiovasc Dev Dis 2018; 5:jcdd5020030. [PMID: 29789495 PMCID: PMC6023389 DOI: 10.3390/jcdd5020030] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/08/2018] [Accepted: 05/18/2018] [Indexed: 12/26/2022] Open
Abstract
Apolipoprotein (apo) E stands out among plasma apolipoproteins through its unprecedented ability to protect against atherosclerosis. Although best recognized for its ability to mediate plasma lipoprotein clearance in the liver and protect against macrophage foam cell formation, our recent understanding of the influence that apoE can exert to control atherosclerosis has significantly widened. Among apoE’s newfound athero-protective properties include an ability to control exaggerated hematopoiesis, blood monocyte activation and aortic stiffening in mice with hyperlipidemia. Mechanisms responsible for these exciting new properties extend beyond apoE’s ability to prevent cellular lipid excess. Rather, new findings have revealed a role for apoE in regulating microRNA-controlled cellular signaling in cells of the immune system and vascular wall. Remarkably, infusions of apoE-responsive microRNA mimics were shown to substitute for apoE in protecting against systemic and vascular inflammation to suppress atherosclerosis in mice with hyperlipidemia. Finally, more recent evidence suggests that apoE may control the release of microvesicles that could modulate cellular signaling, inflammation and atherosclerosis at a distance. These exciting new findings position apoE within the emerging field of intercellular communication that could introduce new approaches to control atherosclerosis cardiovascular disease.
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8
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Immunosuppression With FTY720 Reverses Cardiac Dysfunction in Hypomorphic ApoE Mice Deficient in SR-BI Expression That Survive Myocardial Infarction Caused by Coronary Atherosclerosis. J Cardiovasc Pharmacol 2016; 67:47-56. [PMID: 26322923 DOI: 10.1097/fjc.0000000000000312] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AIMS We recently reported that immunosuppression with FTY720 improves cardiac function and extends longevity in Hypomorphic ApoE mice deficient in scavenger receptor Type-BI expression, also known as the HypoE/SR-BI(–/–) mouse model of diet-induced coronary atherosclerosis and myocardial infarction (MI). In this study, we tested the impact of FTY720 on cardiac dysfunction in HypoE/SR-BI(–/–) mice that survive MI and subsequently develop chronic heart failure. METHODS/RESULTS HypoE/SR-BI(–/–) mice were bred to Mx1-Cre transgenic mice, and offspring were fed a high-fat diet (HFD) for 3.5 weeks to provoke hyperlipidemia, coronary atherosclerosis, and recurrent MIs. In contrast to our previous study, hyperlipidemia was rapidly reversed by inducible Cre-mediated gene repair of the HypoE allele and switching mice to a normal chow diet. Mice that survived the period of HFD were subsequently given oral FTY720 in drinking water or not, and left ventricular (LV) function was monitored using serial echocardiography for up to 15 weeks. In untreated mice, LV performance progressively deteriorated. Although FTY720 treatment did not initially prevent a decline of heart function among mice 6 weeks after Cre-mediated gene repair, it almost completely restored normal LV function in these mice by 15 weeks. Reversal of heart failure did not result from reduced atherosclerosis as the burden of aortic and coronary atherosclerosis actually increased to similar levels in both groups of mice. Rather, FTY720 caused systemic immunosuppression as assessed by reduced numbers of circulating T and B lymphocytes. In contrast, FTY720 did not enhance the loss of T cells or macrophages that accumulated in the heart during the HFD feeding period, but it did enhance the loss of B cells soon after plasma lipid lowering. Moreover, FTY720 potently reduced the expression of matrix metalloproteinase-2 and genes involved in innate immunity-associated inflammation in the heart. CONCLUSIONS Our data demonstrate that immunosuppression with FTY720 prevents postinfarction myocardial remodeling and chronic heart failure.
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Dose J, Huebbe P, Nebel A, Rimbach G. APOE genotype and stress response - a mini review. Lipids Health Dis 2016; 15:121. [PMID: 27457486 PMCID: PMC4960866 DOI: 10.1186/s12944-016-0288-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/12/2016] [Indexed: 12/31/2022] Open
Abstract
The APOE gene is one of currently only two genes that have consistently been associated with longevity. Apolipoprotein E (APOE) is a plasma protein which plays an important role in lipid and lipoprotein metabolism. In humans, there are three major APOE isoforms, designated APOE2, APOE3, and APOE4. Of these three isoforms, APOE3 is most common while APOE4 was shown to be associated with age-related diseases, including cardiovascular and Alzheimer’s disease, and therefore an increased mortality risk with advanced age. Evidence accumulates, showing that oxidative stress and, correspondingly, mitochondrial function is affected in an APOE isoform-dependent manner. Accordingly, several stress response pathways implicated in the aging process, including the endoplasmic reticulum stress response and immune function, appear to be influenced by the APOE genotype. The investigation and development of treatment strategies targeting APOE4 have not resolved any therapeutic yet that could be entirely recommended. This mini-review provides an overview on the state of research concerning the impact of the APOE genotype on stress response-related processes, emphasizing the strong interconnection between mitochondrial function, endoplasmic reticulum stress and the immune response. Furthermore, this review addresses potential treatment strategies and associated pitfalls as well as lifestyle interventions that could benefit people with an at risk APOE4 genotype.
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Affiliation(s)
- Janina Dose
- Institute of Human Nutrition and Food Science, Kiel University, Hermann-Rodewald-Str. 6, D-24118, Kiel, Germany. .,Institute of Clinical Molecular Biology, Kiel University, Schittenhelmstr. 12, D-24105, Kiel, Germany.
| | - Patricia Huebbe
- Institute of Human Nutrition and Food Science, Kiel University, Hermann-Rodewald-Str. 6, D-24118, Kiel, Germany
| | - Almut Nebel
- Institute of Clinical Molecular Biology, Kiel University, Schittenhelmstr. 12, D-24105, Kiel, Germany
| | - Gerald Rimbach
- Institute of Human Nutrition and Food Science, Kiel University, Hermann-Rodewald-Str. 6, D-24118, Kiel, Germany
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10
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Getz GS, Reardon CA. ApoE knockout and knockin mice: the history of their contribution to the understanding of atherogenesis. J Lipid Res 2016; 57:758-66. [PMID: 27015743 DOI: 10.1194/jlr.r067249] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Indexed: 12/16/2022] Open
Abstract
ApoE is a multifunctional protein that is expressed by many cell types that influences many aspects of cardiovascular physiology. In humans, there are three major allelic variants that differentially influence lipoprotein metabolism and risk for the development of atherosclerosis. Apoe-deficient mice and human apoE isoform knockin mice, as well as hypomorphic Apoe mice, have significantly contributed to our understanding of the role of apoE in lipoprotein metabolism, monocyte/macrophage biology, and atherosclerosis. This brief history of these mouse models will highlight their contribution to the understanding of the role of apoE in these processes. These Apoe(-/-) mice have also been extensively utilized as an atherosensitive platform upon which to assess the impact of modulator genes on the development and regression of atherosclerosis.
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Affiliation(s)
- Godfrey S Getz
- Department of Pathology University of Chicago, Chicago, IL
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Nguyen D, Dhanasekaran P, Nickel M, Mizuguchi C, Watanabe M, Saito H, Phillips MC, Lund-Katz S. Influence of domain stability on the properties of human apolipoprotein E3 and E4 and mouse apolipoprotein E. Biochemistry 2014; 53:4025-33. [PMID: 24871385 PMCID: PMC4071092 DOI: 10.1021/bi500340z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
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The human apolipoprotein (apo) E4
isoform, which differs from wild-type
apoE3 by the single amino acid substitution C112R, is associated with
elevated risk of cardiovascular and Alzheimer’s diseases, but
the molecular basis for this variation between isoforms is not understood.
Human apoE is a two-domain protein comprising an N-terminal helix
bundle and a separately folded C-terminal region. Here, we examine
the concept that the ability of the protein to bind to lipid surfaces
is influenced by the stability (or readiness to unfold) of these domains.
The lipid-free structures and abilities to bind to lipid and lipoprotein
particles of a series of human and mouse apoE variants with varying
domain stabilities and domain–domain interactions are compared.
As assessed by urea denaturation, the two domains are more unstable
in apoE4 than in apoE3. To distinguish the contributions of the destabilization
of each domain to the greater lipid-binding ability of apoE4, the
properties of the apoE4 R61T and E255A variants, which have the same
helix bundle stabilities but altered C-terminal domain stabilities,
are compared. In these cases, the effects on lipid-binding properties
are relatively minor, indicating that the destabilization of the helix
bundle domain is primarily responsible for the enhanced lipid-binding
ability of apoE4. Unlike human apoE, mouse apoE behaves essentially
as a single domain, and its lipid-binding characteristics are more
similar to those of apoE4. Together, the results show that the overall
stability of the entire apoE molecule exerts a major influence on
its lipid- and lipoprotein-binding properties.
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Genetic variants of ApoE and ApoER2 differentially modulate endothelial function. Proc Natl Acad Sci U S A 2014; 111:13493-8. [PMID: 25197062 DOI: 10.1073/pnas.1402106111] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
It is poorly understood why there is greater cardiovascular disease risk associated with the apolipoprotein E4 (apoE) allele vs. apoE3, and also greater risk with the LRP8/apolipoprotein E receptor 2 (ApoER2) variant ApoER2-R952Q. Little is known about the function of the apoE-ApoER2 tandem outside of the central nervous system. We now report that in endothelial cells apoE3 binding to ApoER2 stimulates endothelial NO synthase (eNOS) and endothelial cell migration, and it also attenuates monocyte-endothelial cell adhesion. However, apoE4 does not stimulate eNOS or endothelial cell migration or dampen cell adhesion, and alternatively it selectively antagonizes apoE3/ApoER2 actions. The contrasting endothelial actions of apoE4 vs. apoE3 require the N-terminal to C-terminal interaction in apoE4 that distinguishes it structurally from apoE3. Reconstitution experiments further reveal that ApoER2-R952Q is a loss-of-function variant of the receptor in endothelium. Carotid artery reendothelialization is decreased in ApoER2(-/-) mice, and whereas adenoviral-driven apoE3 expression in wild-type mice has no effect, apoE4 impairs reendothelialization. Moreover, in a model of neointima formation invoked by carotid artery endothelial denudation, ApoER2(-/-) mice display exaggerated neointima development. Thus, the apoE3/ApoER2 tandem promotes endothelial NO production, endothelial repair, and endothelial anti-inflammatory properties, and it prevents neointima formation. In contrast, apoE4 and ApoER2-R952Q display dominant-negative action and loss of function, respectively. Thus, genetic variants of apoE and ApoER2 impact cardiovascular health by differentially modulating endothelial function.
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Gaudreault N, Kumar N, Olivas VR, Eberlé D, Stephens K, Raffai RL. Hyperglycemia impairs atherosclerosis regression in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:1981-1992. [PMID: 24113453 DOI: 10.1016/j.ajpath.2013.08.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/23/2013] [Accepted: 08/12/2013] [Indexed: 02/01/2023]
Abstract
Diabetic patients are known to be more susceptible to atherosclerosis and its associated cardiovascular complications. However, the effects of hyperglycemia on atherosclerosis regression remain unclear. We hypothesized that hyperglycemia impairs atherosclerosis regression by modulating the biological function of lesional macrophages. HypoE (Apoe(h/h)Mx1-Cre) mice express low levels of apolipoprotein E (apoE) and develop atherosclerosis when fed a high-fat diet. Atherosclerosis regression occurs in these mice upon plasma lipid lowering induced by a change in diet and the restoration of apoE expression. We examined the morphological characteristics of regressed lesions and assessed the biological function of lesional macrophages isolated with laser-capture microdissection in euglycemic and hyperglycemic HypoE mice. Hyperglycemia induced by streptozotocin treatment impaired lesion size reduction (36% versus 14%) and lipid loss (38% versus 26%) after the reversal of hyperlipidemia. However, decreases in lesional macrophage content and remodeling in both groups of mice were similar. Gene expression analysis revealed that hyperglycemia impaired cholesterol transport by modulating ATP-binding cassette A1, ATP-binding cassette G1, scavenger receptor class B family member (CD36), scavenger receptor class B1, and wound healing pathways in lesional macrophages during atherosclerosis regression. Hyperglycemia impairs both reduction in size and loss of lipids from atherosclerotic lesions upon plasma lipid lowering without significantly affecting the remodeling of the vascular wall.
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Affiliation(s)
- Nathalie Gaudreault
- Surgical Service, VA Medical Center San Francisco, San Francisco, California; Division of Vascular and Endovascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California
| | - Nikit Kumar
- Surgical Service, VA Medical Center San Francisco, San Francisco, California; Division of Vascular and Endovascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California
| | - Victor R Olivas
- Surgical Service, VA Medical Center San Francisco, San Francisco, California; Division of Vascular and Endovascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California
| | - Delphine Eberlé
- Surgical Service, VA Medical Center San Francisco, San Francisco, California; Division of Vascular and Endovascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California
| | - Kyle Stephens
- Surgical Service, VA Medical Center San Francisco, San Francisco, California; Division of Vascular and Endovascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California
| | - Robert L Raffai
- Surgical Service, VA Medical Center San Francisco, San Francisco, California; Division of Vascular and Endovascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California.
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Abstract
PURPOSE OF REVIEW Apolipoprotein (apo) E is a multifunctional protein that has long been recognized for its ability to safeguard against atherosclerosis. Among its pleiotropic roles known to suppress atherosclerosis, mechanisms by which apoE regulates cells of the immune system have remained elusive. Because atherosclerosis is a chronic inflammatory disease that remains on the rise, understanding in more detail how apoE controls immune cell activation and function is of much interest. RECENT FINDINGS Literature reported in the past year introduces apoE as a regulator of monocyte and macrophage plasticity. Through signals delivered by its interaction with cell surface receptors, apoE has been shown to influence the polarity and inflammatory phenotypes of the macrophage. By promoting cellular cholesterol efflux in a cell autonomous manner and through its ability to enhance HDL function in hyperlipidemic plasma, apoE is now known to suppress atherosclerosis by controlling myeloid cell proliferation, monocyte activation and their capacity to infiltrate the vascular wall. Lastly, the structural basis for apoE isoform-specific effects in macrophage dysfunction and atherosclerosis susceptibility is beginning to emerge. SUMMARY Collectively, these findings introduce a new dimension to our understanding of how apoE links lipoprotein biology to monocyte and macrophage function in atherosclerosis susceptibility.
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Affiliation(s)
- Robert L Raffai
- Department of Surgery, University of California San Francisco, and Veterans Affairs Medical Center, San Francisco, California 94121, USA.
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Cash JG, Kuhel DG, Basford JE, Jaeschke A, Chatterjee TK, Weintraub NL, Hui DY. Apolipoprotein E4 impairs macrophage efferocytosis and potentiates apoptosis by accelerating endoplasmic reticulum stress. J Biol Chem 2012; 287:27876-84. [PMID: 22730380 DOI: 10.1074/jbc.m112.377549] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein (apo) E4 is a major genetic risk factor for a wide spectrum of inflammatory metabolic diseases, including atherosclerosis, diabetes, and Alzheimer disease. This study compared diet-induced adipose tissue inflammation as well as functional properties of macrophages isolated from human APOE3 and APOE4 mice to identify the mechanism responsible for the association between apoE4 and inflammatory metabolic diseases. The initial study confirmed previous reports that APOE4 gene replacement mice were less sensitive than APOE3 mice to diet-induced body weight gain but exhibited hyperinsulinemia, and their adipose tissues were similarly inflamed as those in APOE3 mice. Peritoneal macrophages isolated from APOE4 mice were defective in efferocytosis compared with APOE3 macrophages. Increased cell death was also observed in APOE4 macrophages when stimulated with LPS or oxidized LDL. Western blot analysis of cell lysates revealed that APOE4 macrophages displayed elevated JNK phosphorylation indicative of cell stress even under basal culturing conditions. Significantly higher cell stress due mainly to potentiation of endoplasmic reticulum (ER) stress signaling was also observed in APOE4 macrophages after LPS and oxidized LDL activation. The defect in efferocytosis and elevated apoptosis sensitivity of APOE4 macrophages was ameliorated by treatment with the ER chaperone tauroursodeoxycholic acid. Taken together, these results showed that apoE4 expression causes macrophage dysfunction and promotes apoptosis via ER stress induction. The reduction of ER stress in macrophages may be a viable option to reduce inflammation and inflammation-related metabolic disorders associated with the apoE4 polymorphism.
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Affiliation(s)
- James G Cash
- Department of Pathology and Laboratory Medicine, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio 45237, USA
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