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Quantitative profiling of brain lipid raft proteome in a mouse model of fragile X syndrome. PLoS One 2015; 10:e0121464. [PMID: 25849048 PMCID: PMC4388542 DOI: 10.1371/journal.pone.0121464] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 02/12/2015] [Indexed: 11/19/2022] Open
Abstract
Fragile X Syndrome, a leading cause of inherited intellectual disability and autism, arises from transcriptional silencing of the FMR1 gene encoding an RNA-binding protein, Fragile X Mental Retardation Protein (FMRP). FMRP can regulate the expression of approximately 4% of brain transcripts through its role in regulation of mRNA transport, stability and translation, thus providing a molecular rationale for its potential pleiotropic effects on neuronal and brain circuitry function. Several intracellular signaling pathways are dysregulated in the absence of FMRP suggesting that cellular deficits may be broad and could result in homeostatic changes. Lipid rafts are specialized regions of the plasma membrane, enriched in cholesterol and glycosphingolipids, involved in regulation of intracellular signaling. Among transcripts targeted by FMRP, a subset encodes proteins involved in lipid biosynthesis and homeostasis, dysregulation of which could affect the integrity and function of lipid rafts. Using a quantitative mass spectrometry-based approach we analyzed the lipid raft proteome of Fmr1 knockout mice, an animal model of Fragile X syndrome, and identified candidate proteins that are differentially represented in Fmr1 knockout mice lipid rafts. Furthermore, network analysis of these candidate proteins reveals connectivity between them and predicts functional connectivity with genes encoding components of myelin sheath, axonal processes and growth cones. Our findings provide insight to aid identification of molecular and cellular dysfunctions arising from Fmr1 silencing and for uncovering shared pathologies between Fragile X syndrome and other autism spectrum disorders.
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He M, Smith LD, Chang R, Li X, Vockley J. The role of sterol-C4-methyl oxidase in epidermal biology. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:331-5. [PMID: 24144731 DOI: 10.1016/j.bbalip.2013.10.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/30/2013] [Accepted: 10/01/2013] [Indexed: 01/09/2023]
Abstract
Deficiency of sterol C4 methyl oxidase, encoded by the SC4MOL gene, has recently been described in four patients from three different families. All of the patients presented with microcephaly, congenital cataracts, and growth delay in infancy. The first patient has suffered since the age of six years from severe, diffuse, psoriasiform dermatitis, sparing only her palms. She is now 20 years old. The second patient is a 5 year old girl who has just started to develop dry skin and hair changes. The third and fourth patients are a pair of affected siblings with a severe skin condition since infancy. Quantitative sterol analysis of plasma and skin scales from all four patients showed marked elevation of 4α-methyl- and 4, 4'-dimethylsterols, consistent with a deficiency in the first step of sterol C4 demethylation in cholesterol biosynthesis. Mutations in the SC4MOL have been identified in all of the patients. SC4MOL deficiency is the first autosomal recessive disorder identified in the sterol demethylation complex. Cellular studies with patient-derived fibroblasts have shown a higher mitotic rate than control cells in cholesterol-depleted medium, with increased de novo cholesterol biosynthesis and accumulation of methylsterols. Immunologic analyses of granulocytes and B cells from patients and obligate carriers in the patients' families indicated dysregulation of immune-related receptors. Inhibition of sterol C4 methyl oxidase in human transformed lymphoblasts induced activation of the cell cycle. Additional studies also demonstrated diminished EGFR signaling and disrupted vesicular trafficking in cells from the affected patients. These findings suggest that methylsterols play an important role in epidermal biology by their influence on cell proliferation, intracellular signaling, vesicular trafficking and immune response. SC4MOL is situated within the psoriasis susceptibility locus PSORS9, and may be a genetic risk factor for common skin conditions. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.
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Affiliation(s)
- Miao He
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, PA 19104, USA.
| | - Laurie D Smith
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Richard Chang
- Division of Metabolic Disorders, CHOC Children's, Orange, CA, USA
| | - Xueli Li
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, PA 19104, USA
| | - Jerry Vockley
- Department of Pediatrics, University of Pittsburgh School of Medicine, Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA USA
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Lee RW, Conley SK, Gropman A, Porter FD, Baker EH. Brain magnetic resonance imaging findings in Smith-Lemli-Opitz syndrome. Am J Med Genet A 2013; 161A:2407-19. [PMID: 23918729 PMCID: PMC3787998 DOI: 10.1002/ajmg.a.36096] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 05/28/2013] [Indexed: 01/03/2023]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a neurodevelopmental disorder caused by inborn errors of cholesterol metabolism resulting from mutations in 7-dehydrocholesterol reductase (DHCR7). There are only a few studies describing the brain imaging findings in SLOS. This study examines the prevalence of magnetic resonance imaging (MRI) abnormalities in the largest cohort of patients with SLOS to date. Fifty-five individuals with SLOS (27 M, 28 F) between age 0.17 years and 25.4 years (mean = 6.2, SD = 5.8) received a total of 173 brain MRI scans (mean = 3.1 per subject) on a 1.5T GE scanner between September 1998 and December 2003, or on a 3T Philips scanner between October 2010 and September 2012; all exams were performed at the Clinical Center of the National Institutes of Health. We performed a retrospective review of these imaging studies for both major and minor brain anomalies. Aberrant MRI findings were observed in 53 of 55 (96%) SLOS patients, with abnormalities of the septum pellucidum the most frequent (42/55, 76%) finding. Abnormalities of the corpus callosum were found in 38 of 55 (69%) patients. Other findings included cerebral atrophy, cerebellar atrophy, colpocephaly, white matter lesions, arachnoid cysts, Dandy-Walker variant, and type I Chiari malformation. Significant correlations were observed when comparing MRI findings with sterol levels and somatic malformations. Individuals with SLOS commonly have anomalies involving the midline and para-midline structures of the brain. Further studies are required to examine the relationship between structural brain abnormalities and neurodevelopmental disability in SLOS.
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Affiliation(s)
- Ryan W.Y. Lee
- Department of Neurology andDevelopmental Medicine, Kennedy Krieger Institute, Baltimore, MD
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Sandra K. Conley
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Andrea Gropman
- Department of Neurology, Children’s National Medical Center, Washington DC
| | - Forbes D. Porter
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Eva H. Baker
- Department of Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD
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Lee RWY, Yoshida S, Jung ES, Mori S, Baker EH, Porter FD. Corpus callosum measurements correlate with developmental delay in Smith-Lemli-Opitz syndrome. Pediatr Neurol 2013; 49:107-12. [PMID: 23859856 PMCID: PMC3718481 DOI: 10.1016/j.pediatrneurol.2013.03.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/06/2013] [Accepted: 03/19/2013] [Indexed: 02/05/2023]
Abstract
BACKGROUND Smith-Lemli-Opitz syndrome (SLOS) is a multiple malformation, neurodevelopmental disorder of cholesterol metabolism caused by mutations in 7-dehydrocholesterol reductase. Corpus callosum (CC) malformations and developmental delay are common, but the relation between the two has not been evaluated. This study hypothesizes shorter callosal length and smaller area correlate with higher serum 7-dehydrocholesterol and increased severity of neurodevelopmental delay in SLOS. METHODS Thirty-six individuals with SLOS (18M/18F) between 0.20 and 12.5 years (mean = 3.9, SD = 3.6) and 36 typically developing controls (18 boys and 18 girls) between 0.12 and 12.8 years (mean = 4.0, SD = 3.6) were each imaged once on a 1.5T scanner. One midsagittal image per study was selected for manual CC measurement. Gross motor, fine motor, and language developmental quotients; anatomical severity score; and serum sterol levels were assessed. RESULTS Shorter CC length and smaller area correlated with a lower developmental quotient in gross motor and language domains. Furthermore, length and area negatively correlated with a serum sterol precursors and severity score, and positively correlated with total cholesterol. Degree of developmental delay ranged from mild to severe, involving all domains. CONCLUSIONS For individuals with SLOS, smaller callosal area and length are associated with higher 7-dehydrocholesterol, severity scores, and developmental delay. The relationship between callosal development and biochemical abnormalities in this cohort may lead to further studies supporting imaging biomarkers.
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Affiliation(s)
- Ryan W Y Lee
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, Maryland, USA.
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Ren G, Jacob RF, Kaulin Y, DiMuzio P, Xie Y, Mason RP, Tint GS, Steiner RD, Roulett JB, Merkens L, Whitaker-Mendez D, Frank PG, Lisanti M, Cox RH, Tulenko TN. Alterations in membrane caveolae and BKCa channel activity in skin fibroblasts in Smith-Lemli-Opitz syndrome. Mol Genet Metab 2011; 104:346-55. [PMID: 21724437 PMCID: PMC3365561 DOI: 10.1016/j.ymgme.2011.04.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 04/30/2011] [Indexed: 12/20/2022]
Abstract
The Smith-Lemli-Opitz syndrome (SLOS) is an inherited disorder of cholesterol synthesis caused by mutations in DHCR7 which encodes the final enzyme in the cholesterol synthesis pathway. The immediate precursor to cholesterol synthesis, 7-dehydrocholesterol (7-DHC) accumulates in the plasma and cells of SLOS patients which has led to the idea that the accumulation of abnormal sterols and/or reduction in cholesterol underlies the phenotypic abnormalities of SLOS. We tested the hypothesis that 7-DHC accumulates in membrane caveolae where it disturbs caveolar bilayer structure-function. Membrane caveolae from skin fibroblasts obtained from SLOS patients were isolated and found to accumulate 7-DHC. In caveolar-like model membranes containing 7-DHC, subtle, but complex alterations in intermolecular packing, lipid order and membrane width were observed. In addition, the BK(Ca) K(+) channel, which co-migrates with caveolin-1 in a membrane fraction enriched with cholesterol, was impaired in SLOS cells as reflected by reduced single channel conductance and a 50 mV rightward shift in the channel activation voltage. In addition, a marked decrease in BK(Ca) protein but not mRNA expression levels was seen suggesting post-translational alterations. Accompanying these changes was a reduction in caveolin-1 protein and mRNA levels, but membrane caveolar structure was not altered. These results are consistent with the hypothesis that 7-DHC accumulation in the caveolar membrane results in defective caveolar signaling. However, additional cellular alterations beyond mere changes associated with abnormal sterols in the membrane likely contribute to the pathogenesis of SLOS.
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Affiliation(s)
- Gongyi Ren
- Department of Surgery, Cooper University Hospital, Camden, NJ
| | - Robert F. Jacob
- Elucida Research LLC, Beverly, MA, Department of Surgery, Thomas Jefferson University College of Medicine, Philadelphia, PA
| | - Yuri Kaulin
- Department of Anatomy and Cell Biology, Thomas Jefferson University College of Medicine, Philadelphia, PA
| | - Paul DiMuzio
- Elucida Research LLC, Beverly, MA, Department of Surgery, Thomas Jefferson University College of Medicine, Philadelphia, PA
| | - Yi Xie
- Department of Surgery, Cooper University Hospital, Camden, NJ
| | - R. Preston Mason
- Elucida Research LLC, Beverly, MA, Department of Surgery, Thomas Jefferson University College of Medicine, Philadelphia, PA
- Brigham & Women's Hospital, Harvard Medical School, Boston, MA
| | - G. Stephen Tint
- Research Service, Department of Veterans Affairs Medical Center, East Orange, NJ and Department of Medicine, UMDNJ-New Jersey Medical School, Newark, NJ
| | - Robert D. Steiner
- Departments of Pediatrics and Molecular & Medical Genetics, Child Development and Rehabilitation Center, Doernbecher Children’s Hospital, Oregon Health & Science University, Portland, OR
| | - Jean-Baptiste Roulett
- Departments of Pediatrics and Molecular & Medical Genetics, Child Development and Rehabilitation Center, Doernbecher Children’s Hospital, Oregon Health & Science University, Portland, OR
| | - Louise Merkens
- Departments of Pediatrics and Molecular & Medical Genetics, Child Development and Rehabilitation Center, Doernbecher Children’s Hospital, Oregon Health & Science University, Portland, OR
| | - Diana Whitaker-Mendez
- Department of Stem Cell Biology & Regenerative Medicine, and Cancer Biology, Thomas Jefferson University College of Medicine, Philadelphia, PA
| | - Phillipe G. Frank
- Department of Stem Cell Biology & Regenerative Medicine, and Cancer Biology, Thomas Jefferson University College of Medicine, Philadelphia, PA
| | - Michael Lisanti
- Department of Stem Cell Biology & Regenerative Medicine, and Cancer Biology, Thomas Jefferson University College of Medicine, Philadelphia, PA
| | - Robert H. Cox
- Lankenau Institute for Medical Research, Wynnewood, PA
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Benesch MGK, Mannock DA, Lewis RNAH, McElhaney RN. A Calorimetric and Spectroscopic Comparison of the Effects of Lathosterol and Cholesterol on the Thermotropic Phase Behavior and Organization of Dipalmitoylphosphatidylcholine Bilayer Membranes. Biochemistry 2011; 50:9982-97. [DOI: 10.1021/bi200721j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew G. K. Benesch
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - David A. Mannock
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Ruthven N. A. H. Lewis
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Ronald N. McElhaney
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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He M, Kratz LE, Michel JJ, Vallejo AN, Ferris L, Kelley RI, Hoover JJ, Jukic D, Gibson KM, Wolfe LA, Ramachandran D, Zwick ME, Vockley J. Mutations in the human SC4MOL gene encoding a methyl sterol oxidase cause psoriasiform dermatitis, microcephaly, and developmental delay. J Clin Invest 2011; 121:976-84. [PMID: 21285510 DOI: 10.1172/jci42650] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 12/08/2010] [Indexed: 01/10/2023] Open
Abstract
Defects in cholesterol synthesis result in a wide variety of symptoms, from neonatal lethality to the relatively mild dysmorphic features and developmental delay found in individuals with Smith-Lemli-Opitz syndrome. We report here the identification of mutations in sterol-C4-methyl oxidase–like gene (SC4MOL) as the cause of an autosomal recessive syndrome in a human patient with psoriasiform dermatitis, arthralgias, congenital cataracts, microcephaly, and developmental delay. This gene encodes a sterol-C4-methyl oxidase (SMO), which catalyzes demethylation of C4-methylsterols in the cholesterol synthesis pathway. C4-Methylsterols are meiosis-activating sterols (MASs). They exist at high concentrations in the testis and ovary and play roles in meiosis activation. In this study, we found that an accumulation of MASs in the patient led to cell overproliferation in both skin and blood. SMO deficiency also substantially altered immunocyte phenotype and in vitro function. MASs serve as ligands for liver X receptors α and β(LXRα and LXRβ), which are important in regulating not only lipid transport in the epidermis, but also innate and adaptive immunity. Deficiency of SMO represents a biochemical defect in the cholesterol synthesis pathway, the clinical spectrum of which remains to be defined.
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Affiliation(s)
- Miao He
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
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Lee RWY, Tierney E. Hypothesis: the role of sterols in autism spectrum disorder. AUTISM RESEARCH AND TREATMENT 2011; 2011:653570. [PMID: 22937253 PMCID: PMC3420784 DOI: 10.1155/2011/653570] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 02/07/2011] [Accepted: 02/21/2011] [Indexed: 11/17/2022]
Abstract
A possible role for sterols in the development of autism spectrum disorder (ASD) has not been proven, but studies in disorders of sterol biosynthesis, chiefly Smith-Lemli-Opitz syndrome (SLOS), enable hypotheses on a causal relationship to be discussed. Advances in genetic technology coupled with discoveries in membrane physiology have led to renewed interest for lipids in the nervous system. This paper hypothesizes on the role of sterol dysfunction in ASD through the framework of SLOS. Impaired sonic hedgehog patterning, alterations in membrane lipid rafts leading to abnormal synaptic plasticity, and impaired neurosteroid synthesis are discussed. Potential therapeutic agents include the development of neuroactive steroid-based agents and enzyme-specific drugs. Future investigations should reveal the specific mechanisms underlying sterol dysfunction in neurodevelopmental disorders by utilizing advanced imaging and molecular techniques.
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Affiliation(s)
- Ryan W. Y. Lee
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, 716 North Broadway Street, Baltimore, MD 21205, USA
- Department of Pediatrics, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA
| | - Elaine Tierney
- Department of Psychiatry, Kennedy Krieger Institute, 716 North Broadway Street, Baltimore, MD 21205, USA
- Department of Psychiatry, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MS 21287, USA
- Center for Genetic Disorders of Cognition and Behavior, Kennedy Krieger Institute, 716 North Broadway Street, Baltimore, MD 21205, USA
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Horvat S, Mcwhir J, Rozman D. Defects in cholesterol synthesis genes in mouse and in humans: lessons for drug development and safer treatments. Drug Metab Rev 2011; 43:69-90. [DOI: 10.3109/03602532.2010.540580] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Huo JZ, Cortez MA, Snead III OC. GABA receptor proteins within lipid rafts in the AY-9944 model of atypical absence seizures. Epilepsia 2009; 50:776-88. [DOI: 10.1111/j.1528-1167.2008.01903.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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