51
|
Cortes VA, Busso D, Mardones P, Maiz A, Arteaga A, Nervi F, Rigotti A. Retracted: Advances in the physiological and pathological implications of cholesterol. Biol Rev Camb Philos Soc 2013; 88:825-43. [DOI: 10.1111/brv.12025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 01/22/2013] [Accepted: 01/25/2013] [Indexed: 01/07/2023]
Affiliation(s)
- Victor A. Cortes
- Department of Nutrition Diabetes and Metabolism; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Marcoleta 367 Edifico de Gastroenterologia 4 piso Santiago Chile
| | - Dolores Busso
- Department of Nutrition Diabetes and Metabolism; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Marcoleta 367 Edifico de Gastroenterologia 4 piso Santiago Chile
| | - Pablo Mardones
- Department of Nutrition Diabetes and Metabolism; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Marcoleta 367 Edifico de Gastroenterologia 4 piso Santiago Chile
| | - Alberto Maiz
- Department of Nutrition Diabetes and Metabolism; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Marcoleta 367 Edifico de Gastroenterologia 4 piso Santiago Chile
| | - Antonio Arteaga
- Department of Nutrition Diabetes and Metabolism; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Marcoleta 367 Edifico de Gastroenterologia 4 piso Santiago Chile
| | - Flavio Nervi
- Department of Gastroenterology; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Santiago Chile
| | - Attilio Rigotti
- Department of Nutrition Diabetes and Metabolism; School of Medicine; Faculty of Medicine; Pontificia Universidad Catolica de Chile; Marcoleta 367 Edifico de Gastroenterologia 4 piso Santiago Chile
| |
Collapse
|
52
|
Niranjan R. Molecular Basis of Etiological Implications in Alzheimer’s Disease: Focus on Neuroinflammation. Mol Neurobiol 2013; 48:412-28. [DOI: 10.1007/s12035-013-8428-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 02/06/2013] [Indexed: 12/31/2022]
|
53
|
Waltl S, Patankar JV, Fauler G, Nusshold C, Ullen A, Eibinger G, Wintersperger A, Kratky D, Malle E, Sattler W. 25-Hydroxycholesterol regulates cholesterol homeostasis in the murine CATH.a neuronal cell line. Neurosci Lett 2013; 539:16-21. [PMID: 23347841 PMCID: PMC3610018 DOI: 10.1016/j.neulet.2013.01.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 01/03/2013] [Accepted: 01/08/2013] [Indexed: 12/20/2022]
Abstract
Aberrant oxysterol biosynthesis is implicated in the pathogenesis of neurodegenerative diseases. During the present study we have investigated the effects of exogenously added 25-hydroxycholesterol (25-HC) on transcription of cholesterol biosynthetic genes, sterol-regulatory element binding protein (SREBP) processing and cholesterol biosynthesis in the murine CATH.a neuronal cell line. A single i.p. injection of lipopolysaccharide resulted in robust induction of cholesterol 25-hydroxylase mRNA and protein levels in brains of treated mice. In vitro, 25-HC upregulated the transcription of ATP-binding cassette transporter A1 (ABCA1) and (to a lesser extent) apolipoprotein E (apoE) in CATH.a neurons. Cholesterol biosynthetic gene expression (squalene synthase, HMG-CoA synthase, HMG-CoA reductase, and SREBP2) was downregulated by 25-HC. 25-HC also significantly attenuated proteolytic processing of SREBP2. Finally, 25-HC downregulated cholesterol biosynthesis in CATH.a neurons. Our results demonstrate that 25-HC is a potent effector oxysterol of neuronal cholesterol homeostasis.
Collapse
Affiliation(s)
- Sabine Waltl
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | | | | | | | | | | | | | | | | | | |
Collapse
|
54
|
Pathogenesis, modulation, and therapy of Alzheimer’s disease: A perspective on roles of liver-X receptors. Transl Neurosci 2013. [DOI: 10.2478/s13380-013-0136-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
AbstractThe pathogenesis of Alzheimer’s disease (AD) has been mostly linked to aberrant amyloid beta (Aβ) and tau proteins metabolism, disturbed lipid/cholesterol homeostasis, and progressive neuroinflammation. Liver X receptors (LXR) are ligand-activated transcription factors, best known as the key regulators of cholesterol metabolism and transport. In addition, LXR signaling has been shown to have significant anti-inflammatory properties. In this brief review, we focus on the outcome of studies implicating LXR in the pathogenesis, modulation, and therapy of AD.
Collapse
|
55
|
Alam MS, Getz M, Safeukui I, Yi S, Tamez P, Shin J, Velázquez P, Haldar K. Genomic expression analyses reveal lysosomal, innate immunity proteins, as disease correlates in murine models of a lysosomal storage disorder. PLoS One 2012; 7:e48273. [PMID: 23094108 PMCID: PMC3477142 DOI: 10.1371/journal.pone.0048273] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 09/21/2012] [Indexed: 12/17/2022] Open
Abstract
Niemann-Pick Type C (NPC) disease is a rare, genetic, lysosomal disorder with progressive neurodegeneration. Poor understanding of the pathophysiology and a lack of blood-based diagnostic markers are major hurdles in the treatment and management of NPC and several additional, neurological lysosomal disorders. To identify disease severity correlates, we undertook whole genome expression profiling of sentinel organs, brain, liver, and spleen of Balb/c Npc1−/− mice relative to Npc1+/− at an asymptomatic stage, as well as early- and late-symptomatic stages. Unexpectedly, we found prominent up regulation of innate immunity genes with age-dependent change in their expression, in all three organs. We shortlisted a set of 12 secretory genes whose expression steadily increased with age in both brain and liver, as potential plasma correlates of neurological and/or liver disease. Ten were innate immune genes with eight ascribed to lysosomes. Several are known to be elevated in diseased organs of murine models of other lysosomal diseases including Gaucher’s disease, Sandhoff disease and MPSIIIB. We validated the top candidate lysozyme, in the plasma of Npc1−/− as well as Balb/c Npc1nmf164 mice (bearing a point mutation closer to human disease mutants) and show its reduction in response to an emerging therapeutic. We further established elevation of innate immunity in Npc1−/− mice through multiple functional assays including inhibition of bacterial infection as well as cellular analysis and immunohistochemistry. These data revealed neutrophil elevation in the Npc1−/− spleen and liver (where large foci were detected proximal to damaged tissue). Together our results yield a set of lysosomal, secretory innate immunity genes that have potential to be developed as pan or specific plasma markers for neurological diseases associated with lysosomal storage and where diagnosis is a major problem. Further, the accumulation of neutrophils in diseased organs (hitherto not associated with NPC) suggests their role in pathophysiology and disease exacerbation.
Collapse
Affiliation(s)
- Md. Suhail Alam
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Michelle Getz
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Innocent Safeukui
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Sue Yi
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Pamela Tamez
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Jenny Shin
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Peter Velázquez
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Microbiology and Immunology, Indiana University School of Medicine, South Bend, Indiana, United States of America
| | - Kasturi Haldar
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
| |
Collapse
|
56
|
Kang J, Rivest S. Lipid metabolism and neuroinflammation in Alzheimer's disease: a role for liver X receptors. Endocr Rev 2012; 33:715-46. [PMID: 22766509 DOI: 10.1210/er.2011-1049] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Liver X receptors (LXR) are nuclear receptors that have emerged as key regulators of lipid metabolism. In addition to their functions as cholesterol sensors, LXR have also been found to regulate inflammatory responses in macrophages. Alzheimer's disease (AD) is a neurodegenerative disease characterized by a progressive cognitive decline associated with inflammation. Evidence indicates that the initiation and progression of AD is linked to aberrant cholesterol metabolism and inflammation. Activation of LXR can regulate neuroinflammation and decrease amyloid-β peptide accumulation. Here, we highlight the role of LXR in orchestrating lipid homeostasis and neuroinflammation in the brain. In addition, diabetes mellitus is also briefly discussed as a significant risk factor for AD because of the appearing beneficial effects of LXR on glucose homeostasis. The ability of LXR to attenuate AD pathology makes them potential therapeutic targets for this neurodegenerative disease.
Collapse
Affiliation(s)
- Jihong Kang
- Department of Physiology and Pathophysiology and Key Laboratory of Molecular Cardiovascular Sciences, State Education Ministry, Peking University Health Science Center, Beijing 100191, China
| | | |
Collapse
|
57
|
Taylor AM, Liu B, Mari Y, Liu B, Repa JJ. Cyclodextrin mediates rapid changes in lipid balance in Npc1-/- mice without carrying cholesterol through the bloodstream. J Lipid Res 2012; 53:2331-42. [PMID: 22892156 DOI: 10.1194/jlr.m028241] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An injection of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) to mice lacking Niemann Pick type C (NPC) protein results in delayed neurodegeneration, decreased inflammation, and prolonged lifespan. Changes in sterol balance observed in Npc1(-/-) mice 24 h after HP-β-CD administration suggest that HP-β-CD facilitates the release of accumulated lysosomal cholesterol, the molecular hallmark of this genetic disorder. Current studies were performed to evaluate the time course of HP-β-CD effects. Within 3 h after HP-β-CD injection, decreases in cholesterol synthesis rates and increases in cholesteryl ester levels were detected in tissues of Npc1(-/-) mice. The levels of RNAs for target genes of sterol-sensing transcription factors were altered by 6 h in liver, spleen, and ileum. Despite the cholesterol-binding capacity of HP-β-CD, there was no evidence of increased cholesterol in plasma or urine of treated Npc1(-/-) mice, suggesting that HP-β-CD does not carry sterol from the lysosome into the bloodstream for ultimate urinary excretion. Similar changes in sterol balance were observed in cultured cells from Npc1(-/-) mice using HP-β-CD and sulfobutylether-β-CD, a variant that can interact with sterol but not facilitate its solubilization. Taken together, our results demonstrate that HP-β-CD works in cells of Npc1(-/-) mice by rapidly liberating lysosomal cholesterol for normal sterol processing within the cytosolic compartment.
Collapse
Affiliation(s)
- Anna M Taylor
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9077, USA
| | | | | | | | | |
Collapse
|
58
|
Miglustat improves purkinje cell survival and alters microglial phenotype in feline Niemann-Pick disease type C. J Neuropathol Exp Neurol 2012; 71:434-48. [PMID: 22487861 DOI: 10.1097/nen.0b013e31825414a6] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Niemann-Pick disease type C (NPC disease) is an incurable cellular lipid-trafficking disorder characterized by neurodegeneration and intralysosomal accumulation of cholesterol and glycosphingolipids. Treatment with miglustat, a small imino sugar that reversibly inhibits glucosylceramide synthase, which is necessary for glycosphingolipid synthesis, has been shown to benefit patients with NPC disease. The mechanism(s) and extent of brain cellular changes underlying this benefit are not understood. To investigate the basis of the efficacy of miglustat, cats with disease homologous to the juvenile-onset form of human NPC disease received daily miglustat orally beginning at 3 weeks of age. The plasma half-life of miglustat was 6.6 ± 1.1 hours, with a tmax, Cmax, and area under the plasma concentration-time curve of 1.7 ± 0.6 hours, 20.3 ± 4.6 μg/mL, and 104.1 ± 16.6 μg hours/mL, respectively. Miglustat delayed the onset of neurological signs and increased the lifespan of treated cats and was associated with decreased GM2 ganglioside accumulation in the cerebellum and improved Purkinje cell survival. Ex vivo examination of microglia from the brains of treated cats revealed normalization of CD1c and class II major histocompatibility complex expression, as well as generation of reactive oxygen species. Together, these results suggest that prolonged Purkinje cell survival, reduced glycosphingolipid accumulation, and/or the modulation of microglial immunophenotype and function contribute to miglustat-induced neurological improvement in treated cats.
Collapse
|
59
|
Liu B. Therapeutic potential of cyclodextrins in the treatment of Niemann-Pick type C disease. ACTA ACUST UNITED AC 2012; 7:289-301. [PMID: 25152773 DOI: 10.2217/clp.12.31] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Niemann-Pick type C (NPC) disease is an autosomal recessive neurovisceral lipid and storage disorder characterized by abnormal sequestration of unesterified cholesterol within the late endosomal/lysosomal compartment of all cells in the body. This disease primarily affects children and is characterized by hepatic and pulmonary dysfunction, neurodegeneration and death at an early age. Currently, there is no effective treatment for NPC disease. It was recently discovered that 2-hydroxypropyl-β-cyclodextrin (2HPBCD), when administered systemically to a murine model of either NPC1 or NPC2 disease, significantly reduced lysosomal cholesterol accumulation in almost every organ, delayed the progression of neurodegeneration and significantly prolonged lifespan by allowing trapped cholesterol within the late endosome/lysosome to be released. When 2HPBCD was administered directly into the CNS of Npc1-/- mice, neurodegeneration was completely prevented. This review will explore the pathophysiology of NPC disease and the use of 2HPBCD as a possible therapeutic modality.
Collapse
Affiliation(s)
- Benny Liu
- The University of Texas Southwestern Medical Center, Department of Internal Medicine, 5323 Harry Hines Blvd, Dallas, TX 75390-9151, USA, Tel.: +1 214 648 3447, ,
| |
Collapse
|
60
|
Cluzeau CVM, Watkins-Chow DE, Fu R, Borate B, Yanjanin N, Dail MK, Davidson CD, Walkley SU, Ory DS, Wassif CA, Pavan WJ, Porter FD. Microarray expression analysis and identification of serum biomarkers for Niemann-Pick disease, type C1. Hum Mol Genet 2012; 21:3632-46. [PMID: 22619379 DOI: 10.1093/hmg/dds193] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Niemann-Pick disease type C (NPC) is a lysosomal storage disorder characterized by liver disease and progressive neurodegeneration. Deficiency of either NPC1 or NPC2 leads to the accumulation of cholesterol and glycosphingolipids in late endosomes and early lysosomes. In order to identify pathological mechanisms underlying NPC and uncover potential biomarkers, we characterized liver gene expression changes in an Npc1 mouse model at six ages spanning the pathological progression of the disease. We identified altered gene expression at all ages, including changes in asymptomatic, 1-week-old mice. Biological pathways showing early altered gene expression included: lipid metabolism, cytochrome P450 enzymes involved in arachidonic acid and drug metabolism, inflammation and immune responses, mitogen-activated protein kinase and G-protein signaling, cell cycle regulation, cell adhesion and cytoskeleton remodeling. In contrast, apoptosis and oxidative stress appeared to be late pathological processes. To identify potential biomarkers that could facilitate monitoring of disease progression, we focused on a subset of 103 differentially expressed genes that encode secreted proteins. Further analysis identified two secreted proteins with increased serum levels in NPC1 patients: galectin-3 (LGALS3), a pro-inflammatory molecule, and cathepsin D (CTSD), a lysosomal aspartic protease. Elevated serum levels of both proteins correlated with neurological disease severity and appeared to be specific for NPC1. Expression of Lgals3 and Ctsd was normalized following treatment with 2-hydroxypropyl-β-cyclodextrin, a therapy that reduces pathological findings and significantly increases Npc1(-/-) survival. Both LGALS3 and CTSD have the potential to aid in diagnosis and serve as biomarkers to monitor efficacy in therapeutic trials.
Collapse
Affiliation(s)
- Celine V M Cluzeau
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, US Department of Health and Human Services, Bethesda, MD 20892, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
61
|
Jakobsson T, Treuter E, Gustafsson JÅ, Steffensen KR. Liver X receptor biology and pharmacology: new pathways, challenges and opportunities. Trends Pharmacol Sci 2012; 33:394-404. [PMID: 22541735 DOI: 10.1016/j.tips.2012.03.013] [Citation(s) in RCA: 240] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/05/2012] [Accepted: 03/26/2012] [Indexed: 01/12/2023]
Abstract
Nuclear receptors (NRs) are master regulators of transcriptional programs that integrate the homeostatic control of almost all biological processes. Their direct mode of ligand regulation and genome interaction is at the core of modern pharmacology. The two liver X receptors LXRα and LXRβ are among the emerging newer drug targets within the NR family. LXRs are best known as nuclear oxysterol receptors and physiological regulators of lipid and cholesterol metabolism that also act in an anti-inflammatory way. Because LXRs control diverse pathways in development, reproduction, metabolism, immunity and inflammation, they have potential as therapeutic targets for diseases as diverse as lipid disorders, atherosclerosis, chronic inflammation, autoimmunity, cancer and neurodegenerative diseases. Recent insights into LXR signaling suggest future targeting strategies aiming at increasing LXR subtype and pathway selectivity. This review discusses the current status of our understanding of LXR biology and pharmacology, with an emphasis on the molecular aspects of LXR signaling that constitute the potential of LXRs as drug targets.
Collapse
Affiliation(s)
- Tomas Jakobsson
- Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institutet, S-14183 Stockholm, Sweden
| | | | | | | |
Collapse
|
62
|
Hong SB, Seo MS, Park SB, Seo YJ, Kim JS, Kang KS. Therapeutic effects of human amniotic epithelial stem cells in Niemann-Pick type C1 mice. Cytotherapy 2012; 14:630-8. [PMID: 22404083 DOI: 10.3109/14653249.2012.663485] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND AIMS Niemann-Pick disease type C1 (NPC) is an autosomal recessive cholesterol-storage disorder characterized by liver dysfunction, hepatosplenomegaly and progressive neurodegeneration. Thus far, studies of NPC mice have been performed mainly to study the brain and neurodegeneration, because degeneration in the brain was known as the primary cause of death in NPC mice. However, NPC is a systemic disease; therefore the purpose of this study was to find the possibility of a general therapeutic effect by applying and tracking transplanted human amniotic epithelial stem cells (hAESC) in NPC mice. METHODS hAESC were administered to NPC homozygous (NPC(-/-)) mice via intravenous injection from 5 weeks of age; each recipient received 5 × 10(5) cells every other week. The body weight of each of the mice was measured every week, and the survival and state of each mouse was evaluated every day. The weight of the organs was measured, and serum chemistry, histology and the intensity of Filipin staining were evaluated. RESULTS The effect of cell transplantation was to extend the life span and reduce the rapid loss of weight. Moreover, alleviation of tissue damage was observed more in hAESC-treated NPC(-/-) mice than in non-treated NPC(-/-) mice. Cholesterol deposition was reduced after transplantation, and the relative weight of the liver was also decreased. CONCLUSIONS These data show that hAESC could delay the degeneration caused by fatal genetic disorders such as NPC. This study presents the prospect of relief of precipitous disease progression and the therapeutic possibility of applying hAESC to fatal genetic disorders.
Collapse
Affiliation(s)
- Saet-Byul Hong
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | | | | | | | | | | |
Collapse
|
63
|
Lee CY, Ruel I, Denis M, Genest J, Kiss RS. Cholesterol trapping in Niemann-Pick disease type B fibroblasts can be relieved by expressing the phosphotyrosine binding domain of GULP. J Clin Lipidol 2012; 7:153-64. [PMID: 23415435 DOI: 10.1016/j.jacl.2012.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/08/2012] [Accepted: 02/13/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Impairment of acid sphingomyelinase (SMase) results in accumulation of sphingomyelin (SM) and cholesterol in late endosomes, the hallmarks of a lysosomal storage disease. OBJECTIVE We describe cellular lipid metabolism in fibroblasts from two patients with novel compound heterozygote mutations in the sphingomyelin phosphodiesterase 1 (SMPD1) gene manifesting as Niemann-Pick disease type B (NPB) and demonstrate mechanisms to overcome the storage defect. METHODS Using biochemical assays and confocal microscopy, we provide evidence that accumulated lysosomal SM and cholesterol can be released by different treatments. RESULTS Defective SMase activity in these fibroblasts results in a 2.5-fold increased cellular mass of SM and cholesterol, increased de novo endogenous cholesterol synthesis, and decreased cholesterol esterification, demonstrating impaired intracellular cholesterol homeostasis. Depletion of exogenous addition of cholesterol for 24 hours or addition of the cholesterol acceptor apolipoprotein A-I are sufficient to restore normal homeostatic responses. In an effort to correct the lysosomal storage phenotype of NPB, we infected the fibroblasts with a lentivirus expressing the phosphotyrosine binding domain of the adapter protein GULP (PTB-GULP). We have previously shown that expression of PTB-GULP in Chinese hamster ovary cells promotes intracellular cholesterol trafficking and ABCA1-mediated cholesterol efflux. We find that expression of PTB-GULP in NPB fibroblasts results in increased ABCA1 expression, increased cellular cholesterol efflux and lysosomal cholesterol redistribution, independent of the impaired SMase and cholesterol presence. CONCLUSION We provide extensive functional characterization of a novel compound heterozygote mutation and provide a novel functional mechanism to overcome lysosomal storage disease defects.
Collapse
Affiliation(s)
- Ching Yin Lee
- Cardiovascular Sciences Research Laboratories, Division of Cardiology, McGill University Health Center/Royal Victoria Hospital, Montréal, Québec, Canada
| | | | | | | | | |
Collapse
|
64
|
Archer A, Srinivas Kitambi S, L. Hallgren S, Pedrelli M, Håkan Olsén K, Mode A, Gustafsson JÅ. The Liver X-Receptor (Lxr) Governs Lipid Homeostasis in Zebrafish during Development. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/ojemd.2012.24012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
65
|
Abstract
Sterol metabolites are critical signaling molecules that regulate metabolism, development, and homeostasis. Oxysterols, bile acids (BAs), and steroids work primarily through cognate sterol-responsive nuclear hormone receptors to control these processes through feed-forward and feedback mechanisms. These signaling pathways are conserved from simple invertebrates to mammals. Indeed, results from various model organisms have yielded fundamental insights into cholesterol and BA homeostasis, lipid and glucose metabolism, protective mechanisms, tissue differentiation, development, reproduction, and even aging. Here, we review how sterols act through evolutionarily ancient mechanisms to control these processes.
Collapse
Affiliation(s)
- Joshua Wollam
- Department of Molecular and Cellular Biology, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA
| | | |
Collapse
|
66
|
Abstract
The CNS is rich in cholesterol, which is essential for neuronal development and survival, synapse maturation, and optimal synaptic activity. Alterations in brain cholesterol homeostasis are linked to neurodegeneration. Studies have demonstrated that Huntington disease (HD), a progressive and fatal neurodegenerative disorder resulting from polyglutamine expansion in the huntingtin protein, is associated with changes in cellular cholesterol metabolism. Emerging evidence from human and animal studies indicates that attenuated brain sterol synthesis and accumulation of cholesterol in neuronal membranes represent two distinct mechanisms occurring in the presence of mutant huntingtin that influence neuronal survival. Increased knowledge of how changes in intraneuronal cholesterol metabolism influence the pathogenesis of HD will provide insights into the potential application of brain cholesterol regulation as a therapeutic strategy for this devastating disease.
Collapse
|
67
|
Unesterified cholesterol accumulation in late endosomes/lysosomes causes neurodegeneration and is prevented by driving cholesterol export from this compartment. J Neurosci 2011; 31:9404-13. [PMID: 21697390 DOI: 10.1523/jneurosci.1317-11.2011] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
While unesterified cholesterol (C) is essential for remodeling neuronal plasma membranes, its role in certain neurodegenerative disorders remains poorly defined. Uptake of sterol from pericellular fluid requires processing that involves two lysosomal proteins, lysosomal acid lipase, which hydrolyzes C esters, and NPC1 (Niemann-Pick type C1). In systemic tissues, inactivation of either protein led to sterol accumulation and cell death, but in the brain, inactivation of only NPC1 caused C sequestration and neurodegeneration. When injected into the CNS of the npc1(-/-) mouse, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), a compound known to prevent this C accumulation, diffused throughout the brain and was excreted with a t(½) of 6.5 h. This agent caused suppression of C synthesis, elevation of C esters, suppression of sterol regulatory-binding protein 2 (SREBP2) target genes, and activation of liver X receptor-controlled genes. These findings indicated that HP-β-CD promoted movement of the sequestered C from lysosomes to the metabolically active pool of C in the cytosolic compartment of cells in the CNS. The ED(50) for this agent in the brain was ∼0.5 mg/kg, and the therapeutic effect lasted >7 d. Continuous infusion of HP-β-CD into the ventricular system of npc1(-/-) animals between 3 and 7 weeks of age normalized the biochemical abnormalities and completely prevented the expected neurodegeneration. These studies support the concept that neurons continuously acquire C from interstitial fluid to permit plasma membrane turnover and remodeling. Inactivation of NPC1 leads to lysosomal C sequestration and neurodegeneration, but this is prevented by the continuous, direct administration of HP-β-CD into the CNS.
Collapse
|
68
|
Peake KB, Campenot RB, Vance DE, Vance JE. Niemann-Pick Type C1 deficiency in microglia does not cause neuron death in vitro. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1121-9. [DOI: 10.1016/j.bbadis.2011.06.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 05/24/2011] [Accepted: 06/08/2011] [Indexed: 02/07/2023]
|
69
|
Allopregnanolone promotes regeneration and reduces β-amyloid burden in a preclinical model of Alzheimer's disease. PLoS One 2011; 6:e24293. [PMID: 21918687 PMCID: PMC3168882 DOI: 10.1371/journal.pone.0024293] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 08/04/2011] [Indexed: 11/20/2022] Open
Abstract
Previously, we demonstrated that allopregnanolone (APα) promoted proliferation of rodent and human neural progenitor cells in vitro. Further, we demonstrated that APα promoted neurogenesis in the hippocampal subgranular zone (SGZ) and reversed learning and memory deficits in the male triple transgenic mouse model of Alzheimer's (3xTgAD). In the current study, we determined the efficacy of APα to promote the survival of newly generated neural cells while simultaneously reducing Alzheimer's disease (AD) pathology in the 3xTgAD male mouse model. Comparative analyses between three different APα treatment regimens indicated that APα administered 1/week for 6 months was maximally efficacious for simultaneous promotion of neurogenesis and survival of newly generated cells and reduction of AD pathology. We further investigated the efficacy of APα to impact Aβ burden. Treatment was initiated either prior to or post intraneuronal Aβ accumulation. Results indicated that APα administered 1/week for 6 months significantly increased survival of newly generated neurons and simultaneously reduced Aβ pathology with greatest efficacy in the pre-pathology treatment group. APα significantly reduced Aβ generation in hippocampus, cortex, and amygdala, which was paralleled by decreased expression of Aβ-binding-alcohol-dehydrogenase. In addition, APα significantly reduced microglia activation as indicated by reduced expression of OX42 while increasing CNPase, an oligodendrocyte myelin marker. Mechanistic analyses indicated that pre-pathology treatment with APα increased expression of liver-X-receptor, pregnane-X-receptor, and 3-hydroxy-3-methyl-glutaryl-CoA-reductase (HMG-CoA-R), three proteins that regulate cholesterol homeostasis and clearance from brain. Together these findings provide preclinical evidence for the optimal treatment regimen of APα to achieve efficacy as a disease modifying therapeutic to promote regeneration while simultaneously decreasing the pathology associated with Alzheimer's disease.
Collapse
|
70
|
Seo Y, Yang SR, Jee MK, Joo EK, Roh KH, Seo MS, Han TH, Lee SY, Ryu PD, Jung JW, Seo KW, Kang SK, Kang KS. Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Protect against Neuronal Cell Death and Ameliorate Motor Deficits in Niemann Pick Type C1 Mice. Cell Transplant 2011; 20:1033-47. [DOI: 10.3727/096368910x545086] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Niemann Pick disease type C1 (NPC) is an autosomal recessive disease characterized by progressive neurological deterioration leading to premature death. In this study, we hypothesized that human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) have the multifunctional abilities to ameliorate NPC symptoms in the brain. To test this hypothesis, hUCB-MSCs were transplanted into the hippocampus of NPC mice in the early asymptomatic stage. This transplantation resulted in the recovery of motor function in the Rota Rod test and impaired cholesterol homeostasis leading to increased levels of cholesterol efflux-related genes such as LXRα, ABCA1, and ABCG5 while decreased levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase were observed in NPC mice. In the cerebrum, hUCB-MSCs enhanced neuronal cell survival and proliferation, where they directly differentiated into electrically active MAP2-positive neurons as demonstrated by whole-cell patch clamping. In addition, we observed that hUCB-MSCs reduced Purkinje neuronal loss by suppression of inflammatory and apoptotic signaling in the cerebellum as shown by immunohistochemistry. We further investigated how hUCB-MSCs enhance cellular survival and inhibit apoptosis in NPC mice. Neuronal cell survival was associated with increased PI3K/AKT and JAK2/STAT3 signaling; moreover, hUCB-MSCs modulated the levels of GABA/glutamate transporters such as GAT1, EAAT2, EAAT3, and GAD6 in NPC mice as assessed by Western blot analysis. Taken together, our findings suggest that hUCB-MSCs might play multifunctional roles in neuronal cell survival and ameliorating motor deficits of NPC mice.
Collapse
Affiliation(s)
- Yoojin Seo
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Se-Ran Yang
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Min Ki Jee
- Department of Veterinary Biotechnology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Eun Kyung Joo
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Kyung-Hwan Roh
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Min-Soo Seo
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Tae Hee Han
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - So Yeong Lee
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Pan Dong Ryu
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Ji-Won Jung
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Kwang-Won Seo
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Soo-Kyung Kang
- Department of Veterinary Biotechnology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Kyung-Sun Kang
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
- Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| |
Collapse
|
71
|
Pfrieger FW, Ungerer N. Cholesterol metabolism in neurons and astrocytes. Prog Lipid Res 2011; 50:357-71. [PMID: 21741992 DOI: 10.1016/j.plipres.2011.06.002] [Citation(s) in RCA: 321] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/11/2011] [Accepted: 06/22/2011] [Indexed: 12/20/2022]
Abstract
Cells in the mammalian body must accurately maintain their content of cholesterol, which is an essential membrane component and precursor for vital signalling molecules. Outside the brain, cholesterol homeostasis is guaranteed by a lipoprotein shuttle between the liver, intestine and other organs via the blood circulation. Cells inside the brain are cut off from this circuit by the blood-brain barrier and must regulate their cholesterol content in a different manner. Here, we review how this is accomplished by neurons and astrocytes, two cell types of the central nervous system, whose cooperation is essential for normal brain development and function. The key observation is a remarkable cell-specific distribution of proteins that mediate different steps of cholesterol metabolism. This form of metabolic compartmentalization identifies astrocytes as net producers of cholesterol and neurons as consumers with unique means to prevent cholesterol overload. The idea that cholesterol turnover in neurons depends on close cooperation with astrocytes raises new questions that need to be addressed by new experimental approaches to monitor and manipulate cholesterol homeostasis in a cell-specific manner. We conclude that an understanding of cholesterol metabolism in the brain and its role in disease requires a close look at individual cell types.
Collapse
Affiliation(s)
- Frank W Pfrieger
- CNRS UPR 3212, University of Strasbourg, Institute of Cellular and Integrative Neurosciences (INCI), 67084 Strasbourg Cedex, France.
| | | |
Collapse
|
72
|
Activation of Liver X Receptor Decreases BACE1 Expression and Activity by Reducing Membrane Cholesterol Levels. Neurochem Res 2011; 36:1910-21. [DOI: 10.1007/s11064-011-0513-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2011] [Indexed: 11/26/2022]
|
73
|
Cheng D, Jenner AM, Shui G, Cheong WF, Mitchell TW, Nealon JR, Kim WS, McCann H, Wenk MR, Halliday GM, Garner B. Lipid pathway alterations in Parkinson's disease primary visual cortex. PLoS One 2011; 6:e17299. [PMID: 21387008 PMCID: PMC3046155 DOI: 10.1371/journal.pone.0017299] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 01/28/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND We present a lipidomics analysis of human Parkinson's disease tissues. We have focused on the primary visual cortex, a region that is devoid of pathological changes and Lewy bodies; and two additional regions, the amygdala and anterior cingulate cortex which contain Lewy bodies at different disease stages but do not have as severe degeneration as the substantia nigra. METHODOLOGY/PRINCIPAL FINDINGS Using liquid chromatography mass spectrometry lipidomics techniques for an initial screen of 200 lipid species, significant changes in 79 sphingolipid, glycerophospholipid and cholesterol species were detected in the visual cortex of Parkinson's disease patients (n = 10) compared to controls (n = 10) as assessed by two-sided unpaired t-test (p-value <0.05). False discovery rate analysis confirmed that 73 of these 79 lipid species were significantly changed in the visual cortex (q-value <0.05). By contrast, changes in 17 and 12 lipid species were identified in the Parkinson's disease amygdala and anterior cingulate cortex, respectively, compared to controls; none of which remained significant after false discovery rate analysis. Using gas chromatography mass spectrometry techniques, 6 out of 7 oxysterols analysed from both non-enzymatic and enzymatic pathways were also selectively increased in the Parkinson's disease visual cortex. Many of these changes in visual cortex lipids were correlated with relevant changes in the expression of genes involved in lipid metabolism and an oxidative stress response as determined by quantitative polymerase chain reaction techniques. CONCLUSIONS/SIGNIFICANCE The data indicate that changes in lipid metabolism occur in the Parkinson's disease visual cortex in the absence of obvious pathology. This suggests that normalization of lipid metabolism and/or oxidative stress status in the visual cortex may represent a novel route for treatment of non-motor symptoms, such as visual hallucinations, that are experienced by a majority of Parkinson's disease patients.
Collapse
Affiliation(s)
- Danni Cheng
- Neuroscience Research Australia, Sydney, New South Wales, Australia
| | - Andrew M. Jenner
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
| | - Guanghou Shui
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- Life Science Institute, National University of Singapore, Singapore, Singapore
| | - Wei Fun Cheong
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
| | - Todd W. Mitchell
- School of Health Sciences, University of Wollongong, Wollongong, New South Wales, Australia
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
| | - Jessica R. Nealon
- School of Chemistry, University of Wollongong, Wollongong, New South Wales, Australia
| | - Woojin S. Kim
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Heather McCann
- Neuroscience Research Australia, Sydney, New South Wales, Australia
| | - Markus R. Wenk
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Glenda M. Halliday
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Brett Garner
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| |
Collapse
|
74
|
Ramirez CM, Liu B, Aqul A, Taylor AM, Repa JJ, Turley SD, Dietschy JM. Quantitative role of LAL, NPC2, and NPC1 in lysosomal cholesterol processing defined by genetic and pharmacological manipulations. J Lipid Res 2011; 52:688-98. [PMID: 21289032 DOI: 10.1194/jlr.m013789] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipoprotein cholesterol taken up by cells is processed in the endosomal/lysosomal (E/L) compartment by the sequential action of lysosomal acid lipase (LAL), Niemann-Pick C2 (NPC2), and Niemann-Pick C1 (NPC1). Inactivation of NPC2 in mouse caused sequestration of unesterified cholesterol (UC) and expanded the whole animal sterol pool from 2,305 to 4,337 mg/kg. However, this pool increased to 5,408 and 9,480 mg/kg, respectively, when NPC1 or LAL function was absent. The transport defect in mutants lacking NPC2 or NPC1, but not in those lacking LAL, was reversed by cyclodextrin (CD), and the ED₅₀ values for this reversal varied from ~40 mg/kg in kidney to >20,000 mg/kg in brain in both groups. This reversal occurred only with a CD that could interact with UC. Further, a CD that could interact with, but not solubilize, UC still overcame the transport defect. These studies showed that processing and export of sterol from the late E/L compartment was quantitatively different in mice lacking LAL, NPC2, or NPC1 function. In both npc2(-/-) and npc1(-/-) mice, the transport defect was reversed by a CD that interacted with UC, likely at the membrane/bulk-water interface, allowing sterol to move rapidly to the export site of the E/L compartment.
Collapse
Affiliation(s)
- Charina M Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical School, Dallas, TX 75390-9151, USA
| | | | | | | | | | | | | |
Collapse
|
75
|
Loane DJ, Washington PM, Vardanian L, Pocivavsek A, Hoe HS, Duff KE, Cernak I, Rebeck GW, Faden AI, Burns MP. Modulation of ABCA1 by an LXR agonist reduces β-amyloid levels and improves outcome after traumatic brain injury. J Neurotrauma 2011; 28:225-36. [PMID: 21175399 PMCID: PMC3037807 DOI: 10.1089/neu.2010.1595] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Traumatic brain injury (TBI) increases brain beta-amyloid (Aβ) in humans and animals. Although the role of Aβ in the injury cascade is unknown, multiple preclinical studies have demonstrated a correlation between reduced Aβ and improved outcome. Therefore, therapeutic strategies that enhance Aβ clearance may be beneficial after TBI. Increased levels of ATP-binding cassette A1 (ABCA1) transporters can enhance Aβ clearance through an apolipoprotein E (apoE)-mediated pathway. By measuring Aβ and ABCA1 after experimental TBI in C57BL/6J mice, we found that Aβ peaked early after injury (1-3 days), whereas ABCA1 had a delayed response (beginning at 3 days). As ABCA1 levels increased, Aβ levels returned to baseline levels-consistent with the known role of ABCA1 in Aβ clearance. To test if enhancing ABCA1 levels could block TBI-induced Aβ, we treated TBI mice with the liver X-receptor (LXR) agonist T0901317. Pre- and post-injury treatment increased ABCA1 levels at 24 h post-injury, and reduced the TBI-induced increase in Aβ. This reduction in Aβ was not due to decreased amyloid precursor protein processing, or a shift in the solubility of Aβ, indicating enhanced clearance. T0901317 also limited motor coordination deficits in injured mice and reduced brain lesion volume. These data indicate that activation of LXR can reduce Aβ accumulation after TBI, and is accompanied by improved functional recovery.
Collapse
Affiliation(s)
- David J. Loane
- Department of Anesthesiology and Center for Shock Trauma and Anesthesiology Research, National Study Center for Trauma and EMS, University of Maryland School of Medicine, Baltimore, Maryland
| | | | - Lilit Vardanian
- Department of Neuroscience, Georgetown University Medical Center, Washington, D.C
| | - Ana Pocivavsek
- Department of Neuroscience, Georgetown University Medical Center, Washington, D.C
| | - Hyang-Sook Hoe
- Department of Neuroscience, Georgetown University Medical Center, Washington, D.C
| | - Karen E. Duff
- Department of Pathology, Taub Institute for Alzheimer Disease Research, and Integrative Neuroscience New York State Psychiatric Institute, Columbia University Medical Center, New York, New York
| | - Ibolja Cernak
- Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland
| | - G. William Rebeck
- Department of Neuroscience, Georgetown University Medical Center, Washington, D.C
| | - Alan I. Faden
- Department of Anesthesiology and Center for Shock Trauma and Anesthesiology Research, National Study Center for Trauma and EMS, University of Maryland School of Medicine, Baltimore, Maryland
| | - Mark P. Burns
- Department of Neuroscience, Georgetown University Medical Center, Washington, D.C
| |
Collapse
|
76
|
Suon S, Zhao J, Villarreal SA, Anumula N, Liu M, Carangia LM, Renger JJ, Zerbinatti CV. Systemic treatment with liver X receptor agonists raises apolipoprotein E, cholesterol, and amyloid-β peptides in the cerebral spinal fluid of rats. Mol Neurodegener 2010; 5:44. [PMID: 21034469 PMCID: PMC2988784 DOI: 10.1186/1750-1326-5-44] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/29/2010] [Indexed: 11/12/2022] Open
Abstract
Background Apolipoprotein E (apoE) is a major cholesterol transport protein found in association with brain amyloid from Alzheimer's disease (AD) patients and the ε4 allele of apoE is a genetic risk factor for AD. Previous studies have shown that apoE forms a stable complex with amyloid β (Aβ) peptides in vitro and that the state of apoE lipidation influences the fate of brain Aβ, i.e., lipid poor apoE promotes Aβ aggregation/deposition while fully lipidated apoE favors Aβ degradation/clearance. In the brain, apoE levels and apoE lipidation are regulated by the liver X receptors (LXRs). Results We investigated the hypothesis that increased apoE levels and lipidation induced by LXR agonists facilitates Aβ efflux from the brain to the cerebral spinal fluid (CSF). We also examined if the brain expression of major apoE receptors potentially involved in apoE-mediated Aβ clearance was altered by LXR agonists. ApoE, cholesterol, Aβ40, and Aβ42 levels were all significantly elevated in the CSF of rats after only 3 days of treatment with LXR agonists. A significant reduction in soluble brain Aβ40 levels was also detected after 6 days of LXR agonist treatment. Conclusions Our novel findings suggest that central Aβ lowering caused by LXR agonists appears to involve an apoE/cholesterol-mediated transport of Aβ to the CSF and that differences between the apoE isoforms in mediating this clearance pathway may explain why individuals carrying one or two copies of APOE ε4 have increased risk for AD.
Collapse
Affiliation(s)
- Sokreine Suon
- Department of Neurosymptomatic Disorders, Merck Research Laboratories, West Point, PA 19486, USA.
| | | | | | | | | | | | | | | |
Collapse
|
77
|
Activation of the liver X receptor increases neuroactive steroid levels and protects from diabetes-induced peripheral neuropathy. J Neurosci 2010; 30:11896-901. [PMID: 20826654 DOI: 10.1523/jneurosci.1898-10.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuroactive steroids act in the peripheral nervous system as physiological regulators and as protective agents for acquired or inherited peripheral neuropathy. In recent years, modulation of neuroactive steroids levels has been studied as a potential therapeutic approach to protect peripheral nerves from damage induced by diabetes. Nuclear receptors of the liver X receptor (LXR) family regulate adrenal steroidogenesis via their ability to control cholesterol homeostasis. Here we show that rat sciatic nerve expresses both LRXα and β isoforms and that these receptors are functional. Activation of liver X receptors using a synthetic ligand results in increased levels of neurosteroids and protection of the sciatic nerve from neuropathy induced by diabetes. LXR ligand treatment of streptozotocin-treated rats increases expression in the sciatic nerve of steroidogenic acute regulatory protein (a molecule involved in the transfer of cholesterol into mitochondria), of the enzyme P450scc (responsible for conversion of cholesterol into pregnenolone), of 5α-reductase (an enzyme involved in the generation of neuroactive steroids) and of classical LXR targets involved in cholesterol efflux, such as ABCA1 and ABCG1. These effects were associated with increased levels of neuroactive steroids (e.g., pregnenolone, progesterone, dihydroprogesterone and 3α-diol) in the sciatic nerve, and with neuroprotective effects on thermal nociceptive activity, nerve conduction velocity, and Na(+), K(+)-ATPase activity. These results suggest that LXR activation may represent a new pharmacological avenue to increase local neuroactive steroid levels that exert neuroprotective effects in diabetic neuropathy.
Collapse
|
78
|
Ramirez CM, Liu B, Taylor AM, Repa JJ, Burns DK, Weinberg AG, Turley SD, Dietschy JM. Weekly cyclodextrin administration normalizes cholesterol metabolism in nearly every organ of the Niemann-Pick type C1 mouse and markedly prolongs life. Pediatr Res 2010; 68:309-15. [PMID: 20581737 PMCID: PMC3065173 DOI: 10.1203/pdr.0b013e3181ee4dd2] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Niemann-Pick type C1 (NPC1) disease arises from a mutation inactivating NPC1 protein that normally moves unesterified cholesterol from the late endosomal/lysosomal complex of cells to the cytosolic compartment for processing. As a result, cholesterol accumulates in every tissue of the body causing liver, lung, and CNS disease. Treatment of the murine model of this disease, the npc1 mouse, s.c. with β-cyclodextrin (4000 mg/kg) one time each week normalized cellular cholesterol metabolism in the liver and most other organs. At the same time, the hepatic dysfunction seen in the untreated npc1 mouse was prevented. The severity of cerebellar neurodegeneration also was ameliorated, although not entirely prevented, and the median lifespan of the animals was doubled. However, in contrast to these other organs, lung showed progressive macrophage infiltration with development of lipoid pneumonitis. These studies demonstrated that weekly cyclodextrin administration overcomes the lysosomal transport defect associated with the NPC1 mutation, nearly normalizes hepatic and whole animal cholesterol pools, and prevents the development of liver disease. Furthermore, this treatment slows cerebellar neurodegeneration but has little or no effect on the development of progressive pulmonary disease.
Collapse
Affiliation(s)
- Charina M Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical School at Dallas, Texas 75390, USA
| | | | | | | | | | | | | | | |
Collapse
|
79
|
Vincent M, Sayre NL, Graham MJ, Crooke RM, Shealy DJ, Liscum L. Evaluation of an anti-tumor necrosis factor therapeutic in a mouse model of Niemann-Pick C liver disease. PLoS One 2010; 5:e12941. [PMID: 20886067 PMCID: PMC2944848 DOI: 10.1371/journal.pone.0012941] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 08/31/2010] [Indexed: 12/02/2022] Open
Abstract
Background Niemann-Pick type C (NPC) disease is a lysosomal storage disease characterized by the accumulation of cholesterol and glycosphingolipids. The majority of NPC patients die in their teen years due to progressive neurodegeneration; however, half of NPC patients also suffer from cholestasis, prolonged jaundice, and hepatosplenomegaly. We previously showed that a key mediator of NPC liver disease is tumor necrosis factor (TNF) α, which is involved in both proinflammatory and apoptotic signaling cascades. In this study, we tested the hypothesis that blocking TNF action with an anti-TNF monoclonal antibody (CNTO5048) will slow the progression of NPC liver disease. Methodology/Principal Findings Treatment of wild-type C57BL/6 mice with NPC1-specific antisense oligonucleotides led to knockdown of NPC1 protein expression in the liver. This caused classical symptoms of NPC liver disease, including hepatic cholesterol accumulation, hepatomegaly, elevated serum liver enzymes, and lipid laden macrophage accumulation. In addition, there was a significant increase in the number of apoptotic cells and a proliferation of stellate cells. Concurrent treatment of NPC1 knockdown mice with anti-TNF had no effect on the primary lipid storage or accumulation of lipid-laden macrophages. However, anti-TNF treatment slightly blunted the increase in hepatic apoptosis and stellate cell activation that was seen with NPC1 knockdown. Conclusions/Significance Current therapeutic options for NPC disease are limited. Our results provide proof of principle that pharmacologically blocking the TNF-α inflammatory cascade can slightly reduce certain markers of NPC disease. Small molecule inhibitors of TNF that penetrate tissues and cross the blood-brain barrier may prove even more beneficial.
Collapse
Affiliation(s)
- Melanie Vincent
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Naomi L. Sayre
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Mark J. Graham
- Cardiovascular Disease Antisense Drug Discovery, Isis Pharmaceuticals, Inc, Carlsbad, California, United States of America
| | - Rosanne M. Crooke
- Cardiovascular Disease Antisense Drug Discovery, Isis Pharmaceuticals, Inc, Carlsbad, California, United States of America
| | - David J. Shealy
- Centocor Research and Development, Inc., Radnor, Pennsylvania, United States of America
| | - Laura Liscum
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
80
|
Rujoi M, Pipalia NH, Maxfield FR. Cholesterol pathways affected by small molecules that decrease sterol levels in Niemann-Pick type C mutant cells. PLoS One 2010; 5:e12788. [PMID: 20877719 PMCID: PMC2943465 DOI: 10.1371/journal.pone.0012788] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 08/23/2010] [Indexed: 02/04/2023] Open
Abstract
Background Niemann-Pick type C (NPC) disease is a genetically inherited multi-lipid storage disorder with impaired efflux of cholesterol from lysosomal storage organelles. Methodology/Principal Findings The effect of screen-selected cholesterol lowering compounds on the major sterol pathways was studied in CT60 mutant CHO cells lacking NPC1 protein. Each of the selected chemicals decreases cholesterol in the lysosomal storage organelles of NPC1 mutant cells through one or more of the following mechanisms: increased cholesterol efflux from the cell, decreased uptake of low-density lipoproteins, and/or increased levels of cholesteryl esters. Several chemicals promote efflux of cholesterol to extracellular acceptors in both non-NPC and NPC1 mutant cells. The uptake of low-density lipoprotein-derived cholesterol is inhibited by some of the studied compounds. Conclusions/Significance Results herein provide the information for prioritized further studies in identifying molecular targets of the chemicals. This approach proved successful in the identification of seven chemicals as novel inhibitors of lysosomal acid lipase (Rosenbaum et al, Biochim. Biophys. Acta. 2009, 1791:1155–1165).
Collapse
Affiliation(s)
- Madalina Rujoi
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
| | - Nina H. Pipalia
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
| | - Frederick R. Maxfield
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
| |
Collapse
|
81
|
Li X, Yeh V, Molteni V. Liver X receptor modulators: a review of recently patented compounds (2007 - 2009). Expert Opin Ther Pat 2010; 20:535-62. [PMID: 20302451 DOI: 10.1517/13543771003621269] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
IMPORTANCE OF THE FIELD Liver X receptors (LXRs) are ligand activated transcription factors involved in cholesterol metabolism, glucose homeostasis, inflammation and lipogenesis. With the important physiological role of LXRs in reverse cholesterol transport (RCT), atherosclerosis is the best investigated therapeutic indication. While atherosclerosis is not yet clinically validated, Wyeth's LXRalpha/beta agonist LXR-623 indicated the key LXR target genes involved in RCT (ABCA1 and ABCG1) are upregulated in peripheral blood cells in a dose-dependent manner. While discontinued for CNS safety concerns, investigation of LXR-623 supports atherosclerosis as a clinical indication, and the possibility of identifying LXR agonists with profiles that avoid the strong lipogenic effects of full LXRalpha/beta agonists. AREAS COVERED IN THIS REVIEW Patents for LXR agonists from late 2006 up to August 2009 with emphasis on chemical matters and relationship to earlier disclosures, the biological data associated with selected analogues and therapeutic indications. WHAT THE READER WILL GAIN An overview of the majority of LXR scaffolds with representative structure activity relationships as well as the companies that are the chief players in the field. TAKE HOME MESSAGE The future application of LXR agonists depends upon the discovery of LXR agents without lipogenic effects. Limiting activation of LXRalpha is a popular strategy.
Collapse
Affiliation(s)
- Xiaolin Li
- Genomics Institute of the Novartis Research Foundation, Department of Medicinal Chemistry, San Diego, CA 92121, USA
| | | | | |
Collapse
|
82
|
Madra M, Sturley SL. Niemann-Pick type C pathogenesis and treatment: from statins to sugars. CLINICAL LIPIDOLOGY 2010; 5:387-395. [PMID: 21394236 PMCID: PMC3050622 DOI: 10.2217/clp.10.19] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The isolation of the causative genes for Niemann-Pick type C disease, a panethnic lysosomal lipid storage disorder, has provided models of how sterols and other lipids such as glycosphingolipids traverse the membranes of eukaryotic cells. Unfortunately, these molecular advances have yet to reciprocate with a cure for this devastating neurodegenerative disorder where neuronal replenishment will most likely yield the greatest benefit. In the meantime, stabilizing treatment strategies based on the removal of presumably toxic metabolites are in place. For example, the small molecule inhibition of glucosylceramide synthase by miglustat limits ganglioside accumulation and is now the only approved treatment of Niemann-Pick type C. In addition, 2-hydroxypropyl-B-cyclodextrin, a lipid chelator, relieves the lysosomal to endoplasmic reticulum blockage and markedly increases the life expectancy of the murine model. Ultimately, these strategies, targeting the primary biochemical lesion in these cells, and others will likely be combined to provide a synergistic cocktail approach to treating this disease.
Collapse
Affiliation(s)
- Moneek Madra
- Department of Pediatrics, Columbia University Medical Center, 630 West 168th St, NY 10032, USA
| | - Stephen L Sturley
- Department of Pediatrics, Columbia University Medical Center, 630 West 168th St, NY 10032, USA
| |
Collapse
|
83
|
Hong C, Duit S, Jalonen P, Out R, Scheer L, Sorrentino V, Boyadjian R, Rodenburg KW, Foley E, Korhonen L, Lindholm D, Nimpf J, van Berkel TJC, Tontonoz P, Zelcer N. The E3 ubiquitin ligase IDOL induces the degradation of the low density lipoprotein receptor family members VLDLR and ApoER2. J Biol Chem 2010; 285:19720-6. [PMID: 20427281 PMCID: PMC2888382 DOI: 10.1074/jbc.m110.123729] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously identified the E3 ubiquitin ligase-inducible degrader of the low density lipoprotein receptor (LDLR) (Idol) as a post-translational modulator of LDLR levels. Idol is a direct target for regulation by liver X receptors (LXRs), and its expression is responsive to cellular sterol status independent of the sterol-response element-binding proteins. Here we demonstrate that Idol also targets two closely related LDLR family members, VLDLR and ApoE receptor 2 (ApoER2), proteins implicated in both neuronal development and lipid metabolism. Idol triggers ubiquitination of the VLDLR and ApoER2 on their cytoplasmic tails, leading to their degradation. We further show that the level of endogenous VLDLR is sensitive to cellular sterol content, Idol expression, and activation of the LXR pathway. Pharmacological activation of the LXR pathway in mice leads to increased Idol expression and to decreased Vldlr levels in vivo. Finally, we establish an unexpected functional link between LXR and Reelin signaling. We demonstrate that LXR activation results in decreased Reelin binding to VLDLR and reduced Dab1 phosphorylation. The identification of VLDLR and ApoER2 as Idol targets suggests potential roles for this LXR-inducible E3 ligase in the central nervous system in addition to lipid metabolism.
Collapse
Affiliation(s)
- Cynthia Hong
- Department of Pathology and Laboratory Medicine and the Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
84
|
Sayre NL, Rimkunas VM, Graham MJ, Crooke RM, Liscum L. Recovery from liver disease in a Niemann-Pick type C mouse model. J Lipid Res 2010; 51:2372-83. [PMID: 20418540 DOI: 10.1194/jlr.m007211] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Loss of function of Niemann-Pick C1 (NPC1) leads to lysosomal free cholesterol storage, resulting in the neurodegenerative disease Niemann-Pick disease type C (NPC). Significant numbers of patients with NPC also suffer from liver disease. Currently, no treatments exist that alter patient outcome, and it is unknown if recovery from tissue damage can occur even if a treatment were found. Our laboratory developed a strategy to test whether mice can recover from NPC liver disease. We used antisense oligonucleotides to knock down hepatic expression of NPC1 in BALB/C mice for either 9 or 15 weeks. This recapitulated liver disease with hepatomegaly, cell death, and fibrosis. Then, antisense oligonucleotide treatment was halted for an additional 4, 9, or 15 weeks. We report that significant liver recovery occurred even when NPC1 protein expression only partially returned to normal. Several pathological phenotypes were alleviated, including hepatomegaly, cholesterol storage, and liver cell death. Histological examination revealed that foamy cell accumulation was relieved; however, liver fibrosis increased. Additionally, resolution of cholesterol storage and liver cell death took longer in mice with long-term knockdown. Finally, we found that transcription of cholesterol homeostatic genes was significantly disrupted during the recovery phase after long-term knockdown.
Collapse
Affiliation(s)
- Naomi L Sayre
- Department of Physiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111
| | | | | | | | | |
Collapse
|
85
|
Peake KB, Vance JE. Defective cholesterol trafficking in Niemann-Pick C-deficient cells. FEBS Lett 2010; 584:2731-9. [PMID: 20416299 DOI: 10.1016/j.febslet.2010.04.047] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 11/29/2022]
Abstract
Pathways of intracellular cholesterol trafficking are poorly understood at the molecular level. Mutations in Niemann-Pick C (NPC) proteins, NPC1 and NPC2, however, have led to insights into the mechanism by which endocytosed cholesterol is exported from late endosomes/lysosomes (LE/L). Mutations in NPC1, a multi-spanning membrane protein of LE/L, or mutations in NPC2, a soluble luminal protein of LE/L, cause the neurodegenerative disorder NPC disease. This review focuses on data supporting a model in which movement of cholesterol out of LE/L is mediated by the sequential action of the two NPC proteins. We also discuss potential therapies for NPC disease, including evidence that treatment of NPC-deficient mice with the cholesterol-binding compound, cyclodextrin, markedly attenuates neurodegeneration, and increases life-span, of NPC1-deficient mice.
Collapse
Affiliation(s)
- Kyle B Peake
- Group on the Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | | |
Collapse
|
86
|
Abnormal gene expression in cerebellum of Npc1-/- mice during postnatal development. Brain Res 2010; 1325:128-40. [PMID: 20153740 DOI: 10.1016/j.brainres.2010.02.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 01/31/2010] [Accepted: 02/04/2010] [Indexed: 11/21/2022]
Abstract
Niemann-Pick Type C (NPC) disease is an autosomal recessive neurodegenerative disorder with abnormal lipid storage as the major cellular pathologic hallmark. Genetic analyses have identified mutations in NPC1 gene in the great majority of cases, while mutations in NPC2 account for the remainders. Yet little is known regarding the cellular mechanisms responsible for NPC pathogenesis, especially for neurodegeneration, which is the usual cause of death. To identify critical steps that could account for the pathological manifestations of the disease in one of the most affected brain structures, we performed global gene expression analysis in the cerebellum from 3-week old Npc1+/+ and Npc1-/- mice with two different microarray platforms (Agilent and Illumina). Differentially expressed genes identified by both microarray platforms were then subjected to KEGG pathway analysis. Expression of genes in six pathways was significantly altered in Npc1-/- mice; functionally, these signaling pathways belong to the following three categories: (1) steroid and terpenoid biosynthesis, (2) immune response, and (3) cell adhesion/motility. In addition, the expression of several proteins involved in lipid transport was significantly altered in Npc1-/- mice. Our results provide novel molecular insight regarding the mechanisms of pathogenesis in NPC disease and reveal potential new therapeutic targets.
Collapse
|
87
|
Yanjanin NM, Vélez JI, Gropman A, King K, Bianconi SE, Conley SK, Brewer CC, Solomon B, Pavan WJ, Arcos-Burgos M, Patterson MC, Porter FD. Linear clinical progression, independent of age of onset, in Niemann-Pick disease, type C. Am J Med Genet B Neuropsychiatr Genet 2010; 153B:132-40. [PMID: 19415691 PMCID: PMC2798912 DOI: 10.1002/ajmg.b.30969] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Niemann-Pick disease, type C is a neurodegenerative, lysosomal storage disorder with a broad clinical spectrum and a variable age of onset. The absence of a universally accepted clinical outcome measure is an impediment to the design of a therapeutic trial for NPC. Thus, we developed a clinical severity scale to characterize and quantify disease progression. Clinical signs and symptoms in nine major (ambulation, cognition, eye movement, fine motor, hearing, memory, seizures, speech, and swallowing) and eight minor (auditory brainstem response, behavior, gelastic cataplexy, hyperreflexia, incontinence, narcolepsy, psychiatric, and respiratory problems) domains were scored. Data were collected from 18 current NPC patients and were extracted from records of 19 patients. Both patient cohorts showed a linear increase in severity scores over time. Cross-sectional evaluation of current patients showed a linear increase in the severity score. Longitudinal chart review of historical data demonstrated that although age of onset varied significantly, the rate of progression appeared linear, independent of age of onset, and similar in all patients. Combining the data from both cohorts, disease progression could be modeled by the following equation: ŝ(t0+x) = ŝ(t0) + 1.87x; where ŝ(t0) is the initial score and ŝ(t0+x) is the predicted future score after x years. Our observation that disease progression is similar across patients and independent of age of onset is consistent with a biphasic pathological model for NPC. This scale may prove useful in the characterization of potential biomarkers, and as an outcome measure to monitor disease progression in NPC patients.
Collapse
Affiliation(s)
- Nicole M. Yanjanin
- Program on Developmental Endocrinology and Genetics, NICHD, NIH, DHHS, Bethesda, MD 20892
| | - Jorge I. Vélez
- Human Development Section, Medical Genetics Branch, NHGRI, NIH, DHHS, Bethesda, MD 20892
| | - Andrea Gropman
- Division of Neurology, Children’s National Medical Center, Washington, DC 20010
| | - Kelly King
- Otolaryngology Branch, NIDCD, NIH, DHHS, Bethesda, MD 20892,Department of Hearing and Speech Sciences, University of Maryland, College Park, MD 20783
| | - Simona E. Bianconi
- Program on Developmental Endocrinology and Genetics, NICHD, NIH, DHHS, Bethesda, MD 20892
| | - Sandra K. Conley
- Program on Developmental Endocrinology and Genetics, NICHD, NIH, DHHS, Bethesda, MD 20892
| | | | - Beth Solomon
- Speech and Language Pathology Section, RMD, CC, NIH, DHHS, Bethesda, MD 20892
| | - William J. Pavan
- Mouse Embryology Section, Genetic Disease Research Branch, NHGRI, NIH, DHHS, Bethesda, MD 20892
| | - Mauricio Arcos-Burgos
- Department of Psychiatry and Behavioral Sciences, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136
| | | | - Forbes D. Porter
- Program on Developmental Endocrinology and Genetics, NICHD, NIH, DHHS, Bethesda, MD 20892,Corresponding Author: Forbes D. Porter, M.D., Ph.D., PDGEN, NICHD, NIH, DHHS, Bld. 10, Rm. 9D42, 10 Center Dr. Bethesda, MD 20892, Phone: 301-435-4432, Fax: 301-480-5791,
| |
Collapse
|
88
|
Abstract
Niemann-Pick Type C (NPC) disease is associated with accumulation of cholesterol and other lipids in late endosomes/lysosomes in virtually every organ; however, neurodegeneration represents the fatal cause for the disease. Genetic analysis has identified loss-of-function mutations in NPC1 and NPC2 genes as the molecular triggers for the disease. Although the precise function of these proteins has not yet been clarified, recent research suggests that they orchestrate cholesterol efflux from late endosomes/lysosomes. NPC protein deficits result in impairment in intracellular cholesterol trafficking and dysregulation of cholesterol biosynthesis. Disruption of cholesterol homeostasis is also associated with deregulation of autophagic activity and early-onset neuroinflammation, which may contribute to the pathogenesis of NPC disease. This chapter reviews recent achievements in the investigation of disruption of cholesterol homeostasis-induced neurodegeneration in NPC disease, and provides new insight for developing a potential therapeutic strategy for this disorder.
Collapse
Affiliation(s)
- Xiaoning Bi
- Department of Basic Medical Sciences, COMP, Western University of Health Sciences, Pomona, CA 91766, USA.
| | | |
Collapse
|
89
|
Expression of sterol 27-hydroxylase in glial cells and its regulation by liver X receptor signaling. Neuroscience 2009; 164:530-40. [DOI: 10.1016/j.neuroscience.2009.08.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 07/31/2009] [Accepted: 08/01/2009] [Indexed: 11/21/2022]
|
90
|
Garenc C, Julien P, Levy E. Oxysterols in biological systems: The gastrointestinal tract, liver, vascular wall and central nervous system. Free Radic Res 2009; 44:47-73. [DOI: 10.3109/10715760903321804] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
91
|
Liu B, Ramirez CM, Miller AM, Repa JJ, Turley SD, Dietschy JM. Cyclodextrin overcomes the transport defect in nearly every organ of NPC1 mice leading to excretion of sequestered cholesterol as bile acid. J Lipid Res 2009; 51:933-44. [PMID: 19965601 DOI: 10.1194/jlr.m000257] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A mutation in NPC1 leads to sequestration of unesterified cholesterol in the late endosomal/lysosomal compartment of every cell culminating in the development of pulmonary, hepatic, and neurodegenerative disease. Acute administration of 2-hydroxypropyl-beta-cyclodextrin (CYCLO) rapidly overcomes this transport defect in both the 7-day-old pup and 49-day-old mature npc1(-/-) mouse, even though this compound is cleared from the body and plasma six times faster in the mature mouse than in the neonatal animal. The liberated cholesterol flows into the cytosolic ester pool, suppresses sterol synthesis, down-regulates SREBP2 and its target genes, and reduces expression of macrophage-associated inflammatory genes. These effects are seen in the liver and brain, as well as in peripheral organs like the spleen and kidney. Only the lung appears to be resistant to these effects. Forty-eight h after CYCLO administration to the 49-day-old animals, fecal acidic, but not neutral, sterol output increases, whole-animal cholesterol burden is reduced, and the hepatic and neurological inflammation is ameliorated. However, lifespan is extended only when the CYCLO is administered to the 7-day-old animals. These studies demonstrate that CYCLO administration acutely reverses the cholesterol transport defect seen in the NPC1 mouse at any age, and this reversal allows the sequestered sterol to be excreted from the body as bile acid.
Collapse
Affiliation(s)
- Benny Liu
- Departments of Internal Medicine, University of Texas Southwestern Medical School, Dallas, TX 75390-9151, USA
| | | | | | | | | | | |
Collapse
|
92
|
Claudepierre T, Paques M, Simonutti M, Buard I, Sahel J, Maue RA, Picaud S, Pfrieger FW. Lack of Niemann-Pick type C1 induces age-related degeneration in the mouse retina. Mol Cell Neurosci 2009; 43:164-76. [PMID: 19883762 DOI: 10.1016/j.mcn.2009.10.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 10/17/2009] [Indexed: 11/26/2022] Open
Abstract
Niemann-Pick type C (NPC) disease is an inherited lysosomal storage disease and caused by mutations in Npc1 or Npc2, which mediate cooperatively the egress of cholesterol from lysosomes. The disease entails progressive neurodegeneration, whose cause is poorly understood. Here, we report that Npc1 is distributed in distinct layers of the mouse retina and that its deficiency causes striking retinal degeneration in 2-month-old mice with signs of age-related maculopathies. This includes impaired visual function, accumulation of lipofuscin in the retinal pigment epithelium layer, degeneration of photoreceptor outer segments, disruption of synaptic layers and an increase in autophagy markers in the ganglion cell layer. Moreover, the lack of Npc1 results in the upregulation of proteins that mediate cellular cholesterol release in the retina. Our findings suggest that Npc1 is required for normal retinal function and that its absence may serve as model to study age-related degeneration of the retina.
Collapse
Affiliation(s)
- Thomas Claudepierre
- CNRS UPR 3212, University of Strasbourg, Institute of Cellular and Integrative Neurosciences (INCI), 5, rue Blaise Pascal, F-67084 Strasbourg, France
| | | | | | | | | | | | | | | |
Collapse
|
93
|
Kim JH, Jittiwat J, Ong WY, Farooqui AA, Jenner AM. Changes in cholesterol biosynthetic and transport pathways after excitotoxicity. J Neurochem 2009; 112:34-41. [PMID: 19860851 DOI: 10.1111/j.1471-4159.2009.06449.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study was carried out to elucidate changes in the gene expression and activity of cholesterol biosynthetic enzymes and transporters in the rat hippocampus after kainate excitotoxicity. Significantly increased cholesterol level was detected in the degenerating hippocampus, reaching double normal levels at 1 week after kainate injury. RT-PCR analyses of hippocampal homogenates showed significantly decreased mRNA expression of the transcription factor controlling cholesterol biosynthesis SREBP-2, and the rate-controlling enzyme HMG-CoA (3-hydroxy-3-methyl-glutaryl-CoA) reductase at all time points after kainate injection; and decreased lanosterol synthase and CYP51 at 1 and 2 weeks post-kainate injection respectively. GC-MS analyses showed a significant increase in cholesterol biosynthetic precursors lanosterol, desmosterol and 7-dehydrocholesterol at 1 day after kainate injection presumably reflecting biosysnthesis in injured neurons, and significant decreases in precursors at 1 and 2 weeks post-kainate injection, at time of gliosis in the degenerating hippocampus. Levels of cholesterol autooxidation including 7 ketocholesterol and cholesterol epoxides were elevated in the kainate lesioned hippocampus. Furthermore, loss of expression of the cholesterol transporter, ABCA1 was detected in neurons, but increased expression in astrocytes was detected after kainate lesions. The results suggest that increased cholesterol biosynthesis and loss of ABCA1 expression in injured neurons might result in increase in cholesterol in the degenerating hippocampus. The increased cholesterol might predispose to increased formation of cholesterol oxidation products which have been shown to be toxic to neurons.
Collapse
Affiliation(s)
- Ji-Hyun Kim
- Department of Anatomy, National University of Singapore, Singapore
| | | | | | | | | |
Collapse
|
94
|
Lee JH, Park SM, Kim OS, Lee CS, Woo JH, Park SJ, Joe EH, Jou I. Differential SUMOylation of LXRalpha and LXRbeta mediates transrepression of STAT1 inflammatory signaling in IFN-gamma-stimulated brain astrocytes. Mol Cell 2009; 35:806-17. [PMID: 19782030 DOI: 10.1016/j.molcel.2009.07.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 04/13/2009] [Accepted: 07/24/2009] [Indexed: 01/04/2023]
Abstract
To unravel the roles of LXRs in inflammation and immunity, we examined the function of LXRs in development of IFN-gamma-mediated inflammation using cultured rat brain astrocytes. LXR ligands inhibit neither STAT1 phosphorylation nor STAT1 translocation to the nucleus but, rather, inhibit STAT1 binding to promoters and the expression of IRF1, TNFalpha, and IL-6, downstream effectors of STAT1 action. Immunoprecipitation data revealed that LXRbeta formed a trimer with PIAS1-pSTAT1, whereas LXRalpha formed a trimer with HDAC4-pSTAT1, mediated by direct ligand binding to the LXR proteins. In line with the fact that both PIAS1 and HDAC4 belong to the SUMO E3 ligase family, LXRbeta and LXRalpha were SUMO-conjugated by PIAS1 or HDAC4, respectively, and SUMOylation was blocked by transient transfection of appropriate individual siRNAs, reversing LXR-induced suppression of IRF1 and TNFalpha expression. Together, our data show that SUMOylation is required for the suppression of STAT1-dependent inflammatory responses by LXRs in IFN-gamma-stimulated brain astrocytes.
Collapse
Affiliation(s)
- Jee Hoon Lee
- Department of Pharmacology and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon 442-721, Korea
| | | | | | | | | | | | | | | |
Collapse
|
95
|
Bartzokis G. Alzheimer's disease as homeostatic responses to age-related myelin breakdown. Neurobiol Aging 2009; 32:1341-71. [PMID: 19775776 DOI: 10.1016/j.neurobiolaging.2009.08.007] [Citation(s) in RCA: 385] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 08/13/2009] [Accepted: 08/17/2009] [Indexed: 12/11/2022]
Abstract
The amyloid hypothesis (AH) of Alzheimer's disease (AD) posits that the fundamental cause of AD is the accumulation of the peptide amyloid beta (Aβ) in the brain. This hypothesis has been supported by observations that genetic defects in amyloid precursor protein (APP) and presenilin increase Aβ production and cause familial AD (FAD). The AH is widely accepted but does not account for important phenomena including recent failures of clinical trials to impact dementia in humans even after successfully reducing Aβ deposits. Herein, the AH is viewed from the broader overarching perspective of the myelin model of the human brain that focuses on functioning brain circuits and encompasses white matter and myelin in addition to neurons and synapses. The model proposes that the recently evolved and extensive myelination of the human brain underlies both our unique abilities and susceptibility to highly prevalent age-related neuropsychiatric disorders such as late onset AD (LOAD). It regards oligodendrocytes and the myelin they produce as being both critical for circuit function and uniquely vulnerable to damage. This perspective reframes key observations such as axonal transport disruptions, formation of axonal swellings/sphenoids and neuritic plaques, and proteinaceous deposits such as Aβ and tau as by-products of homeostatic myelin repair processes. It delineates empirically testable mechanisms of action for genes underlying FAD and LOAD and provides "upstream" treatment targets. Such interventions could potentially treat multiple degenerative brain disorders by mitigating the effects of aging and associated changes in iron, cholesterol, and free radicals on oligodendrocytes and their myelin.
Collapse
Affiliation(s)
- George Bartzokis
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| |
Collapse
|
96
|
Vik-Mo AO, Fernø J, Skrede S, Steen VM. Psychotropic drugs up-regulate the expression of cholesterol transport proteins including ApoE in cultured human CNS- and liver cells. BMC Pharmacol 2009; 9:10. [PMID: 19715613 PMCID: PMC2753324 DOI: 10.1186/1471-2210-9-10] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 08/29/2009] [Indexed: 01/20/2023] Open
Abstract
Background Disturbances in lipid homeostasis and myelination have been proposed in the pathophysiology of schizophrenia and bipolar disorder. We have previously shown that several antipsychotic and antidepressant drugs increase lipid biosynthesis through activation of the Sterol Regulatory Element-Binding Protein (SREBP) transcription factors, which control the expression of numerous genes involved in fatty acid and cholesterol biosynthesis. The aim of the present proof-of-principle study was to investigate whether such drugs also affect lipid transport and export pathways in cultured human CNS and liver cells. Results Quantitative PCR and immunoblotting were used to determine the level of lipid transport genes in human glioblastoma (GaMg) exposed to clozapine, olanzapine, haloperidol or imipramine. The effect of some of these drugs was also investigated in human astrocytoma (CCF-STTG1), neuroblastoma (SH-SY5Y) and hepatocellular carcinoma (HepG2) cells. We found significant transcriptional changes of cholesterol transport genes (ApoE, ABCA1, NPC1, NPC2, NPC1L1), which are predominantly controlled by the Liver X receptor (LXR) transcription factor. The up-regulation was observed after 24 to 48 hours of drug exposure, which is markedly delayed as compared to the drug-induced SREBP-controlled stimulation of lipid biosynthesis seen after 6 hours. Conclusion Our data show that stimulation of cellular lipid biosynthesis by amphiphilic psychotropic drugs is followed by a transcriptional activation of cholesterol transport and efflux pathways. Such effects may be relevant for both therapeutic effects and metabolic adverse effects of psychotropic drugs.
Collapse
Affiliation(s)
- Audun O Vik-Mo
- Department of Clinical Medicine, University of Bergen, Dr Einar Martens' Research Group for Biological Psychiatry and Bergen Mental Health Research Center, Norway.
| | | | | | | |
Collapse
|
97
|
Vanmierlo T, Rutten K, Dederen J, Bloks VW, van Vark-van der Zee LC, Kuipers F, Kiliaan A, Blokland A, Sijbrands EJG, Steinbusch H, Prickaerts J, Lütjohann D, Mulder M. Liver X receptor activation restores memory in aged AD mice without reducing amyloid. Neurobiol Aging 2009; 32:1262-72. [PMID: 19674815 DOI: 10.1016/j.neurobiolaging.2009.07.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 06/03/2009] [Accepted: 07/10/2009] [Indexed: 11/19/2022]
Abstract
Alterations in cerebral cholesterol metabolism are thought to play a role in the progression of Alzheimer's disease (AD). Liver X receptors (LXRs) are key regulators of cholesterol metabolism. The synthetic LXR activator, T0901317 has been reported to improve memory functions in animal models for AD and to reduce amyloid-β (Aβ) deposition in the brain. Here we provide evidence that long-term administration of T0901317 to aged, 21-month-old APPSLxPS1mut mice restores impaired memory. Cerebral cholesterol turnover was enhanced as indicated by the increased levels of brain cholesterol precursors and the upregulation of LXR-target genes Abca1, Abcg1, and Apoe. Unexpectedly, the improved memory functions in the APPSLxPS1mut mice after T0901317 treatment were not accompanied by a decrease in Aβ plaque load in the cortex or hippocampus DG, CA1 or CA3. T0901317 administration also enhanced cerebral cholesterol turnover in aged C57BL/6NCrl mice, but did not further improve their memory functions. In conclusion, long-term activation of the LXR-pathway restored memory functions in aged APPSLxPS1mut mice with advanced Aβ deposition. However the beneficial effects of T0901317 on memory in the APPSLxPS1mut mice were independent of the Aβ plaque load in the hippocampus, but were associated with enhanced brain cholesterol turnover.
Collapse
Affiliation(s)
- Tim Vanmierlo
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
98
|
Peng D, Hiipakka RA, Xie JT, Reardon CA, Getz GS, Liao S. Differential effects of activation of liver X receptor on plasma lipid homeostasis in wild-type and lipoprotein clearance-deficient mice. Atherosclerosis 2009; 208:126-33. [PMID: 19632679 DOI: 10.1016/j.atherosclerosis.2009.07.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/29/2009] [Accepted: 07/01/2009] [Indexed: 10/20/2022]
Abstract
The effects of liver X receptor (LXR) agonists on plasma lipid homeostasis, especially triglyceride metabolism are controversial. Here we examined the effect of long-term activation of LXR on plasma lipid homeostasis in wild-type C57BL/6 and LDL receptor deficient (LDLR-/-) mice given the LXR agonist T0901317 for 4 weeks. LXR agonist treatment of wild-type mice decreased plasma total triglycerides by 35% due to a significant reduction of plasma VLDL triglycerides. In contrast, in LDLR-/- mice T0901317 treatment increased plasma total cholesterol and triglycerides. An increase in the level of smaller VLDL particles was also observed in T0901317-treated LDLR-/- mice. The changes in circulating lipoprotein profiles in response to T0901317 treatment in these two animal models reflect the balance between synthesis and secretion on the one hand and lipolysis and clearance on the other. In both models there was both an increase in VLDL production and secretion and in an increase in LPL production and activity in T0901317-treated animals. In wild-type mice lipolysis and clearance predominates, while in the absence of the LDLR, which plays a major role in the clearance of apoB-containing lipoproteins, the increased output predominates. The generation of elevated levels of small VLDL particles due to increased lipolysis may represent an additional risk factor for atherosclerosis.
Collapse
Affiliation(s)
- Dacheng Peng
- Ben May Department for Cancer Research, University of Chicago, 929 E 57th Street, Chicago, IL 60637, USA
| | | | | | | | | | | |
Collapse
|
99
|
Dietschy JM. Central nervous system: cholesterol turnover, brain development and neurodegeneration. Biol Chem 2009; 390:287-93. [PMID: 19166320 DOI: 10.1515/bc.2009.035] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The average amount of cholesterol in the whole animal equals approximately 2100 mg/kg body weight, and 15% and 23% of this sterol in the mouse and human, respectively, is found in the central nervous system. There is no detectable uptake across the blood-brain barrier of cholesterol carried in lipoproteins in the plasma, even in the newborn. However, high rates of de novo cholesterol synthesis in the glia and neurons provide the sterol necessary for early brain development. Once a stable brain size is achieved in the adult, cholesterol synthesis continues, albeit at a much lower rate, and this synthesis is just balanced by the excretion of an equal amount of sterol, either as 24(S)-hydroxycholesterol or, presumably, as cholesterol itself.
Collapse
Affiliation(s)
- John M Dietschy
- Department of Internal Medicine, University of TexasSouthwestern Medical School, Dallas, TX 75390-9151,USA.
| |
Collapse
|
100
|
Liu JP. New functions of cholesterol binding proteins. Mol Cell Endocrinol 2009; 303:1-6. [PMID: 19428985 DOI: 10.1016/j.mce.2009.01.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 01/10/2009] [Accepted: 01/12/2009] [Indexed: 11/22/2022]
Abstract
Cholesterol is an essential component of eukaryotic cell membranes with an important role in signal transduction. Although cholesterol can operate to auto-regulate its own disposal via gene transcriptional mechanisms, glucose also binds to the same cholesterol-binding transcription factors to regulate gene expression. Different sterol binding proteins bind different lipids to regulate both lipid homeostasis and antigen presentation. This mini-review examines the recently reported new functions of cholesterol binding proteins in cholesterol homeostasis, function and trafficking, and explores the molecular mechanisms whereby sterol sensors respond to glucose and other ligands to regulate diverse cellular functions in metabolism. Several new models are proposed from studies on a range of sterol binding proteins including Insig, SCAP, LXR, HMG-CoAR, NPC1 and NPC2.
Collapse
Affiliation(s)
- Jun-Ping Liu
- Department of Immunology, Monash University Central Clinical School, Prahran, Victoria, Australia.
| |
Collapse
|