1
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Hadar D, Strugach DS, Amiram M. Conjugates of Recombinant Protein‐Based Polymers: Combining Precision with Chemical Diversity. ADVANCED NANOBIOMED RESEARCH 2022. [DOI: 10.1002/anbr.202100142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Dagan Hadar
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering Ben-Gurion University of the Negev P.O. Box 653 Beer-Sheva 8410501 Israel
| | - Daniela S. Strugach
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering Ben-Gurion University of the Negev P.O. Box 653 Beer-Sheva 8410501 Israel
| | - Miriam Amiram
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering Ben-Gurion University of the Negev P.O. Box 653 Beer-Sheva 8410501 Israel
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2
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Cannarozzo C, Fred SM, Girych M, Biojone C, Enkavi G, Róg T, Vattulainen I, Casarotto PC, Castrén E. Cholesterol-recognition motifs in the transmembrane domain of the tyrosine kinase receptor family: The case of TRKB. Eur J Neurosci 2021; 53:3311-3322. [PMID: 33825223 DOI: 10.1111/ejn.15218] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 01/19/2023]
Abstract
Cholesterol is an essential constituent of cell membranes. The discovery of cholesterol-recognition amino acid consensus (CRAC) motif in proteins indicated a putative direct, non-covalent interaction between cholesterol and proteins. In the present study, we evaluated the presence of a CRAC motif and its inverted version (CARC) in the transmembrane region (TMR) of the tyrosine kinase receptor family (RTK) in several species using in silico methods. CRAC motifs were found across all species analyzed, while CARC was found only in vertebrates. The tropomyosin-related kinase B (TRKB), a member of the RTK family, through interaction with its endogenous ligand brain-derived neurotrophic factor (BDNF) is a core participant in the neuronal plasticity process and exhibits a CARC motif in its TMR. Upon identifying the conserved CARC motif in the TRKB, we performed molecular dynamics simulations of the mouse TRKB.TMR. The simulations indicated that cholesterol interaction with the TRKB CARC motif occurs mainly at the central Y433 residue. Our binding assay suggested a bell-shaped effect of cholesterol on BDNF interaction with TRKB receptors, and our results suggest that CARC/CRAC motifs may play a role in the function of the RTK family TMR.
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Affiliation(s)
| | - Senem Merve Fred
- Neuroscience Center - HiLife, University of Helsinki, Helsinki, Finland
| | - Mykhailo Girych
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Caroline Biojone
- Neuroscience Center - HiLife, University of Helsinki, Helsinki, Finland
| | - Giray Enkavi
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Tomasz Róg
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland
- Computational Physics Laboratory, Tampere University, Tampere, Finland
| | | | - Eero Castrén
- Neuroscience Center - HiLife, University of Helsinki, Helsinki, Finland
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3
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Gholizadeh E, Belibel R, Bachelart T, Bounadji C, Barbaud C. Chemical grafting of cholesterol on monomer and PDMMLA polymers, a step towards the development of new polymers for biomedical applications. RSC Adv 2020; 10:32602-32608. [PMID: 35516467 PMCID: PMC9056615 DOI: 10.1039/d0ra06033j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/23/2020] [Indexed: 11/21/2022] Open
Abstract
Racemic α,α,β-trisubstituted β-lactones are the monomer units of poly((R,S)-3,3-dimethylmalic acid) (PDMMLA) derivatives, new biopolyesters showing great potential for biomedical applications. Using different groups during the synthesis of these β-lactones allows a tailored synthesis of PDMMLA copolymers with adjustable hydrophilic/phobic ratio. The degradation kinetics of the employed material is one of the most important criteria in the development of bioresorbable implants. The degradation time of PDMMLA derivatives can be controlled using different β-lactones of different hydrophilicity levels during the polymerization stage. Furthermore, PDMMLA has chemically available groups on its side chain allowing to graft functional groups on the polymer via covalent bonds. In this work, following a Steglich esterification protocol, the chemical grafting of cholesterol was carried out on a PDMMLA monomer derived β-lactone as well as on homopolymer PDMMLA-H, and copolymer PDMMLAH40-co-Hex60 (PDMMLA 40/60). Nuclear magnetic resonance (NMR) analyses of the products confirm and quantify the grafting ratio. 100% of cholesterol grafting has been realized on the homopolymer PDMMLA-H giving PDMMLA-Chol, and 10% on the copolymer PDMMLA 40/60, giving PDMMLAH30-ter-Chol10-ter-Hex60 (PDMMLA-Chol 30/10/60) as wished. Fourier-transform infrared (FT-IR) spectra, elemental analysis on the β-lactones and thermogravimetric analyses on the polymers also confirm the chemical modification of the products.
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Affiliation(s)
- Elnaz Gholizadeh
- Université Sorbonne Paris Nord, Laboratory for Vascular Transitional Science (LVTS), INSERM UMR 1148 Villetaneuse F-93430 France +33 149403357
| | | | - Thomas Bachelart
- Université Sorbonne Paris Nord, Laboratory for Vascular Transitional Science (LVTS), INSERM UMR 1148 Villetaneuse F-93430 France +33 149403357
| | - Chérifa Bounadji
- Université Sorbonne Paris Nord, Laboratory for Vascular Transitional Science (LVTS), INSERM UMR 1148 Villetaneuse F-93430 France +33 149403357
| | - Christel Barbaud
- Université Sorbonne Paris Nord, Laboratory for Vascular Transitional Science (LVTS), INSERM UMR 1148 Villetaneuse F-93430 France +33 149403357
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4
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Leonova T, Popova V, Tsarev A, Henning C, Antonova K, Rogovskaya N, Vikhnina M, Baldensperger T, Soboleva A, Dinastia E, Dorn M, Shiroglasova O, Grishina T, Balcke GU, Ihling C, Smolikova G, Medvedev S, Zhukov VA, Babakov V, Tikhonovich IA, Glomb MA, Bilova T, Frolov A. Does Protein Glycation Impact on the Drought-Related Changes in Metabolism and Nutritional Properties of Mature Pea ( Pisum sativum L.) Seeds? Int J Mol Sci 2020; 21:E567. [PMID: 31952342 PMCID: PMC7013545 DOI: 10.3390/ijms21020567] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/01/2020] [Accepted: 01/03/2020] [Indexed: 12/24/2022] Open
Abstract
Protein glycation is usually referred to as an array of non-enzymatic post-translational modifications formed by reducing sugars and carbonyl products of their degradation. The resulting advanced glycation end products (AGEs) represent a heterogeneous group of covalent adducts, known for their pro-inflammatory effects in mammals, and impacting on pathogenesis of metabolic diseases and ageing. In plants, AGEs are the markers of tissue ageing and response to environmental stressors, the most prominent of which is drought. Although water deficit enhances protein glycation in leaves, its effect on seed glycation profiles is still unknown. Moreover, the effect of drought on biological activities of seed protein in mammalian systems is still unstudied with respect to glycation. Therefore, here we address the effects of a short-term drought on the patterns of seed protein-bound AGEs and accompanying alterations in pro-inflammatory properties of seed protein in the context of seed metabolome dynamics. A short-term drought, simulated as polyethylene glycol-induced osmotic stress and applied at the stage of seed filling, resulted in the dramatic suppression of primary seed metabolism, although the secondary metabolome was minimally affected. This was accompanied with significant suppression of NF-kB activation in human SH-SY5Y neuroblastoma cells after a treatment with protein hydrolyzates, isolated from the mature seeds of drought-treated plants. This effect could not be attributed to formation of known AGEs. Most likely, the prospective anti-inflammatory effect of short-term drought is related to antioxidant effect of unknown secondary metabolite protein adducts, or down-regulation of unknown plant-specific AGEs due to suppression of energy metabolism during seed filling.
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Affiliation(s)
- Tatiana Leonova
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Veronika Popova
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Alexander Tsarev
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Christian Henning
- Institute of Chemistry - Food Chemistry, Martin-Luther University Halle-Wittenberg, 06120 Halle, Germany
| | - Kristina Antonova
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Nadezhda Rogovskaya
- Research Institute of Hygiene, Occupational Pathology and Human Ecology, 188663 Leningrad Oblast, Russia
| | - Maria Vikhnina
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Tim Baldensperger
- Institute of Chemistry - Food Chemistry, Martin-Luther University Halle-Wittenberg, 06120 Halle, Germany
| | - Alena Soboleva
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Ekaterina Dinastia
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
- Postovsky Institute of Organic Synthesis of Ural Division of Russian Academy of Sciences, 620137 Yekaterinburg, Russia
| | - Mandy Dorn
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Olga Shiroglasova
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Tatiana Grishina
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
| | - Gerd U Balcke
- Department of Metabolic and Cell Biology, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Christian Ihling
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, 06120 Halle, Germany
| | - Galina Smolikova
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Sergei Medvedev
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Vladimir A Zhukov
- All-Russia Research Institute for Agricultural Microbiology, 196608 St. Petersburg, Russia
| | - Vladimir Babakov
- Research Institute of Hygiene, Occupational Pathology and Human Ecology, 188663 Leningrad Oblast, Russia
| | - Igor A Tikhonovich
- All-Russia Research Institute for Agricultural Microbiology, 196608 St. Petersburg, Russia
- Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Marcus A Glomb
- Institute of Chemistry - Food Chemistry, Martin-Luther University Halle-Wittenberg, 06120 Halle, Germany
| | - Tatiana Bilova
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Andrej Frolov
- Department of Biochemistry, St. Petersburg State University, 199004 St. Petersburg, Russia
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
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5
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Mozhdehi D, Luginbuhl KM, Dzuricky M, Costa SA, Xiong S, Huang FC, Lewis MM, Zelenetz SR, Colby CD, Chilkoti A. Genetically Encoded Cholesterol-Modified Polypeptides. J Am Chem Soc 2019; 141:945-951. [PMID: 30608674 DOI: 10.1021/jacs.8b10687] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Biological systems use post-translational modifications (PTMs) to control the structure, location, and function of proteins after expression. Despite the ubiquity of PTMs in biology, their use to create genetically encoded recombinant biomaterials is limited. We have utilized a natural lipidation PTM (hedgehog-mediated cholesterol modification of proteins) to create a class of hybrid biomaterials called cholesterol-modified polypeptides (CHaMPs) that exhibit programmable self-assembly at the nanoscale. To demonstrate the biomedical utility of CHaMPs, we used this approach to append cholesterol to biologically active peptide exendin-4 that is an approved drug for the treatment of type II diabetes. The exendin-cholesterol conjugate self-assembled into micelles, and these micelles activate the glucagon-like peptide-1 receptor with a potency comparable to that of current gold standard treatments.
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Affiliation(s)
- Davoud Mozhdehi
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Kelli M Luginbuhl
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Michael Dzuricky
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Simone A Costa
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Sinan Xiong
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Fred C Huang
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Mae M Lewis
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Stephanie R Zelenetz
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Christian D Colby
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering , Duke University , 1427 FCIEMAS , Box 90281, Durham , North Carolina 27708-0281 , United States
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6
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Tsushima H, Tang YJ, Puviindran V, Hsu SHC, Nadesan P, Yu C, Zhang H, Mirando AJ, Hilton MJ, Alman BA. Intracellular biosynthesis of lipids and cholesterol by Scap and Insig in mesenchymal cells regulates long bone growth and chondrocyte homeostasis. Development 2018; 145:dev.162396. [PMID: 29899135 PMCID: PMC6053657 DOI: 10.1242/dev.162396] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 06/01/2018] [Indexed: 01/12/2023]
Abstract
During enchondral ossification, mesenchymal cells express genes regulating the intracellular biosynthesis of cholesterol and lipids. Here, we have investigated conditional deletion of Scap or of Insig1 and Insig2 (Scap inhibits intracellular biosynthesis and Insig proteins activate intracellular biosynthesis). Mesenchymal condensation and chondrogenesis was disrupted in mice lacking Scap in mesenchymal progenitors, whereas mice lacking the Insig genes in mesenchymal progenitors had short limbs, but normal chondrogenesis. Mice lacking Scap in chondrocytes showed severe dwarfism, with ectopic hypertrophic cells, whereas deletion of Insig genes in chondrocytes caused a mild dwarfism and shortening of the hypertrophic zone. In vitro studies showed that intracellular cholesterol in chondrocytes can derive from exogenous and endogenous sources, but that exogenous sources cannot completely overcome the phenotypic effect of Scap deficiency. Genes encoding cholesterol biosynthetic proteins are regulated by Hedgehog (Hh) signaling, and Hh signaling is also regulated by intracellular cholesterol in chondrocytes, suggesting a feedback loop in chondrocyte differentiation. Precise regulation of intracellular biosynthesis is required for chondrocyte homeostasis and long bone growth, and these data support pharmacological modulation of cholesterol biosynthesis as a therapy for select cartilage pathologies. Summary: Conditional deletion of genes that regulate intracellular cholesterol biosynthesis in mesenchymal cells or chondrocytes shows that precise regulation of biosynthesis is required for chondrocyte homeostasis and long bone growth.
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Affiliation(s)
- Hidetoshi Tsushima
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Yuning J Tang
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Vijitha Puviindran
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Shu-Hsuan Claire Hsu
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Puviindran Nadesan
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Chunying Yu
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Hongyuan Zhang
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Anthony J Mirando
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Matthew J Hilton
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
| | - Benjamin A Alman
- Department of Orthopaedic Surgery and Regeneration Next Initiative, Duke University, Durham, NC 27710, USA
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7
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Chowdhury S, Sinha N, Ganguli P, Bhowmick R, Singh V, Nandi S, Sarkar RR. BIOPYDB: A Dynamic Human Cell Specific Biochemical Pathway Database with Advanced Computational Analyses Platform. J Integr Bioinform 2018; 15:/j/jib.ahead-of-print/jib-2017-0072/jib-2017-0072.xml. [PMID: 29547394 PMCID: PMC6340122 DOI: 10.1515/jib-2017-0072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/29/2018] [Indexed: 12/03/2022] Open
Abstract
BIOPYDB: BIOchemical PathwaY DataBase is developed as a manually curated, readily updatable, dynamic resource of human cell specific pathway information along with integrated computational platform to perform various pathway analyses. Presently, it comprises of 46 pathways, 3189 molecules, 5742 reactions and 6897 different types of diseases linked with pathway proteins, which are referred by 520 literatures and 17 other pathway databases. With its repertoire of biochemical pathway data, and computational tools for performing Topological, Logical and Dynamic analyses, BIOPYDB offers both the experimental and computational biologists to acquire a comprehensive understanding of signaling cascades in the cells. Automated pathway image reconstruction, cross referencing of pathway molecules and interactions with other databases and literature sources, complex search operations to extract information from other similar resources, integrated platform for pathway data sharing and computation, etc. are the novel and useful features included in this database to make it more acceptable and attractive to the users of pathway research communities. The RESTful API service is also made available to the advanced users and developers for accessing this database more conveniently through their own computer programmes.
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Affiliation(s)
- Saikat Chowdhury
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune, Maharashtra 411008, India
| | - Noopur Sinha
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune, Maharashtra 411008, India
| | - Piyali Ganguli
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune, Maharashtra 411008, India
| | - Rupa Bhowmick
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune, Maharashtra 411008, India
| | - Vidhi Singh
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India
| | - Sutanu Nandi
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune, Maharashtra 411008, India
| | - Ram Rup Sarkar
- CSIR- National Chemical Laboratory, Chemical Engineering and Process Development Division, Pune, Maharashtra 411008, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune, Maharashtra 411008, India
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8
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Abstract
Communication between cells pervades the development and physiology of metazoans. In animals, this process is carried out by a relatively small number of signaling pathways, each consisting of a chain of biochemical events through which extracellular stimuli control the behavior of target cells. One such signaling system is the Hedgehog pathway, which is crucial in embryogenesis and is implicated in many birth defects and cancers. Although Hedgehog pathway components were identified by genetic analysis more than a decade ago, our understanding of the molecular mechanisms of signaling is far from complete. In this review, we focus on the biochemistry and cell biology of the Hedgehog pathway. We examine the unique biosynthesis of the Hedgehog ligand, its specialized release from cells into extracellular space, and the poorly understood mechanisms involved in ligand reception and pathway activation at the surface of target cells. We highlight several critical questions that remain open.
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Affiliation(s)
- Kostadin Petrov
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115; ,
| | - Bradley M Wierbowski
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115; ,
| | - Adrian Salic
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115; ,
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9
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7-dehydrocholesterol efficiently supports Ret signaling in a mouse model of Smith-Opitz-Lemli syndrome. Sci Rep 2016; 6:28534. [PMID: 27334845 PMCID: PMC4917867 DOI: 10.1038/srep28534] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 06/06/2016] [Indexed: 11/09/2022] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a rare disorder of cholesterol synthesis. Affected individuals exhibit growth failure, intellectual disability and a broad spectrum of developmental malformations. Among them, renal agenesis or hypoplasia, decreased innervation of the gut, and ptosis are consistent with impaired Ret signaling. Ret is a receptor tyrosine kinase that achieves full activity when recruited to lipid rafts. Mice mutant for Ret are born with no kidneys and enteric neurons, and display sympathetic nervous system defects causing ptosis. Since cholesterol is a critical component of lipid rafts, here we tested the hypothesis of whether the cause of the above malformations found in SLOS is defective Ret signaling owing to improper lipid raft composition or function. No defects consistent with decreased Ret signaling were found in newborn Dhcr7−/− mice, or in Dhcr7−/− mice lacking one copy of Ret. Although kidneys from Dhcr7−/− mice showed a mild branching defect in vitro, GDNF was able to support survival and downstream signaling of sympathetic neurons. Consistently, GFRα1 correctly partitioned to lipid rafts in brain tissue. Finally, replacement experiments demonstrated that 7-DHC efficiently supports Ret signaling in vitro. Taken together, our findings do not support a role of Ret signaling in the pathogenesis of SLOS.
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10
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Sulmann S, Wallisch M, Scholten A, Christoffers J, Koch KW. Mapping Calcium-Sensitive Regions in the Neuronal Calcium Sensor GCAP2 by Site-Specific Fluorescence Labeling. Biochemistry 2016; 55:2567-77. [DOI: 10.1021/acs.biochem.6b00005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefan Sulmann
- Biochemistry
Group, Department of Neurosciences, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Melanie Wallisch
- Institut
für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Alexander Scholten
- Biochemistry
Group, Department of Neurosciences, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Jens Christoffers
- Institut
für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Biochemistry
Group, Department of Neurosciences, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
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11
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Callahan BP, Wang C. Hedgehog Cholesterolysis: Specialized Gatekeeper to Oncogenic Signaling. Cancers (Basel) 2015; 7:2037-53. [PMID: 26473928 PMCID: PMC4695875 DOI: 10.3390/cancers7040875] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/22/2015] [Accepted: 09/28/2015] [Indexed: 12/16/2022] Open
Abstract
Discussions of therapeutic suppression of hedgehog (Hh) signaling almost exclusively focus on receptor antagonism; however, hedgehog's biosynthesis represents a unique and potentially targetable aspect of this oncogenic signaling pathway. Here, we review a key biosynthetic step called cholesterolysis from the perspectives of structure/function and small molecule inhibition. Cholesterolysis, also called cholesteroylation, generates cholesterol-modified Hh ligand via autoprocessing of a hedgehog precursor protein. Post-translational modification by cholesterol appears to be restricted to proteins in the hedgehog family. The transformation is essential for Hh biological activity and upstream of signaling events. Despite its decisive role in generating ligand, cholesterolysis remains conspicuously unexplored as a therapeutic target.
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Affiliation(s)
- Brian P Callahan
- Chemistry Department, Binghamton University 4400 Vestal Parkway East, Binghamton, NY 13902, USA.
| | - Chunyu Wang
- Biology Department, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA.
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12
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Lorent JH, Levental I. Structural determinants of protein partitioning into ordered membrane domains and lipid rafts. Chem Phys Lipids 2015; 192:23-32. [PMID: 26241883 DOI: 10.1016/j.chemphyslip.2015.07.022] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 07/27/2015] [Accepted: 07/29/2015] [Indexed: 11/16/2022]
Abstract
Increasing evidence supports the existence of lateral nanoscopic lipid domains in plasma membranes, known as lipid rafts. These domains preferentially recruit membrane proteins and lipids to facilitate their interactions and thereby regulate transmembrane signaling and cellular homeostasis. The functionality of raft domains is intrinsically dependent on their selectivity for specific membrane components; however, while the physicochemical determinants of raft association for lipids are known, very few systematic studies have focused on the structural aspects that guide raft partitioning of proteins. In this review, we describe biophysical and thermodynamic aspects of raft-mimetic liquid ordered phases, focusing on those most relevant for protein partitioning. Further, we detail the variety of experimental models used to study protein-raft interactions. Finally, we review the existing literature on mechanisms for raft targeting, including lipid post-translational modifications, lipid binding, and transmembrane domain features. We conclude that while protein palmitoylation is a clear raft-targeting signal, few other general structural determinants for raft partitioning have been revealed, suggesting that many discoveries lie ahead in this burgeoning field.
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Affiliation(s)
- Joseph Helmuth Lorent
- Department for Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, USA
| | - Ilya Levental
- Department for Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, USA.
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13
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Lee HJ, Zhang W, Zhang D, Yang Y, Liu B, Barker EL, Buhman KK, Slipchenko LV, Dai M, Cheng JX. Assessing cholesterol storage in live cells and C. elegans by stimulated Raman scattering imaging of phenyl-Diyne cholesterol. Sci Rep 2015; 5:7930. [PMID: 25608867 PMCID: PMC4302291 DOI: 10.1038/srep07930] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/22/2014] [Indexed: 02/07/2023] Open
Abstract
We report a cholesterol imaging method using rationally synthesized phenyl-diyne cholesterol (PhDY-Chol) and stimulated Raman scattering (SRS) microscope. The phenyl-diyne group is biologically inert and provides a Raman scattering cross section that is 88 times larger than the endogenous C = O stretching mode. SRS microscopy offers an imaging speed that is faster than spontaneous Raman microscopy by three orders of magnitude, and a detection sensitivity of 31 μM PhDY-Chol (~1,800 molecules in the excitation volume). Inside living CHO cells, PhDY-Chol mimics the behavior of cholesterol, including membrane incorporation and esterification. In a cellular model of Niemann-Pick type C disease, PhDY-Chol reflects the lysosomal accumulation of cholesterol, and shows relocation to lipid droplets after HPβCD treatment. In live C. elegans, PhDY-Chol mimics cholesterol uptake by intestinal cells and reflects cholesterol storage. Together, our work demonstrates an enabling platform for study of cholesterol storage and trafficking in living cells and vital organisms.
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Affiliation(s)
- Hyeon Jeong Lee
- Interdisciplinary Life Science Program, Purdue University, West Lafayette, IN, USA
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA
| | - Wandi Zhang
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Delong Zhang
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Yang Yang
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Bin Liu
- National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150080, China
| | - Eric L. Barker
- Interdisciplinary Life Science Program, Purdue University, West Lafayette, IN, USA
- Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Kimberly K. Buhman
- Interdisciplinary Life Science Program, Purdue University, West Lafayette, IN, USA
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | | | - Mingji Dai
- Interdisciplinary Life Science Program, Purdue University, West Lafayette, IN, USA
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Ji-Xin Cheng
- Interdisciplinary Life Science Program, Purdue University, West Lafayette, IN, USA
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
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14
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McCarthy N, Eberhart JK. Gene-ethanol interactions underlying fetal alcohol spectrum disorders. Cell Mol Life Sci 2014; 71:2699-706. [PMID: 24554057 PMCID: PMC11114006 DOI: 10.1007/s00018-014-1578-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/14/2014] [Accepted: 01/27/2014] [Indexed: 12/16/2022]
Abstract
Fetal alcohol spectrum disorders (FASD) is an umbrella term that describes a diverse set of ethanol-induced defects. The phenotypic variation is generated by numerous factors, including timing and dosage of ethanol exposure as well as genetic background. We are beginning to learn about how the concentration, duration, and timing of ethanol exposure mediate variability within ethanol teratogenesis. However, little is known about the genetic susceptibilities in FASD. Studies of FASD animal models are beginning to implicate a number of susceptibility genes that are involved in various pathways. Here we review the current literature that focuses on the genetic predispositions in FASD.
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Affiliation(s)
- Neil McCarthy
- Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research, Institute for Cellular and Molecular Biology, University of Texas at Austin,
Austin, TX 78713
USA
| | - Johann K. Eberhart
- Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research, Institute for Cellular and Molecular Biology, University of Texas at Austin,
Austin, TX 78713
USA
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15
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Trinh TN, McLaughlin EA, Gordon CP, McCluskey A. Hedgehog signalling pathway inhibitors as cancer suppressing agents. MEDCHEMCOMM 2014. [DOI: 10.1039/c3md00334e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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16
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Schade M, Knoll A, Vogel A, Seitz O, Liebscher J, Huster D, Herrmann A, Arbuzova A. Remote control of lipophilic nucleic acids domain partitioning by DNA hybridization and enzymatic cleavage. J Am Chem Soc 2012; 134:20490-7. [PMID: 23163619 DOI: 10.1021/ja309256t] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Lateral partitioning of lipid-modified molecules between liquid-disordered (ld) and liquid-ordered (lo) domains depends on the type of lipid modification, presence of a spacer, membrane composition, and temperature. Here, we show that the lo domain partitioning of the palmitoylated peptide nucleic acid (PNA) can be influenced by formation of a four-component complex with the ld domain partitioning tocopherol-modified DNA: the PNA-DNA complex partitioned into the ld domains. Enzymatic cleavage of the DNA linker led to the disruption of the complex and restored the initial distribution of the lipophilic nucleic acids into the respective domains. This modular system offers strategies for dynamic functionalization of biomimetic surfaces, for example, in nanostructuring and regulation of enzyme catalysis, and it provides a tool to study the molecular basis of controlled reorganization of lipid-modified proteins in membranes, for example, during signal transduction.
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Affiliation(s)
- Matthias Schade
- Institute of Biology/Biophysics, Humboldt-University Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
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17
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Vance JE. Dysregulation of cholesterol balance in the brain: contribution to neurodegenerative diseases. Dis Model Mech 2012; 5:746-55. [PMID: 23065638 PMCID: PMC3484857 DOI: 10.1242/dmm.010124] [Citation(s) in RCA: 219] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Dysregulation of cholesterol homeostasis in the brain is increasingly being linked to chronic neurodegenerative disorders, including Alzheimer’s disease (AD), Huntington’s disease (HD), Parkinson’s disease (PD), Niemann-Pick type C (NPC) disease and Smith-Lemli Opitz syndrome (SLOS). However, the molecular mechanisms underlying the correlation between altered cholesterol metabolism and the neurological deficits are, for the most part, not clear. NPC disease and SLOS are caused by mutations in genes involved in the biosynthesis or intracellular trafficking of cholesterol, respectively. However, the types of neurological impairments, and the areas of the brain that are most affected, differ between these diseases. Some, but not all, studies indicate that high levels of plasma cholesterol correlate with increased risk of developing AD. Moreover, inheritance of the E4 isoform of apolipoprotein E (APOE), a cholesterol-carrying protein, markedly increases the risk of developing AD. Whether or not treatment of AD with statins is beneficial remains controversial, and any benefit of statin treatment might be due to anti-inflammatory properties of the drug. Cholesterol balance is also altered in HD and PD, although no causal link between dysregulated cholesterol homeostasis and neurodegeneration has been established. Some important considerations for treatment of neurodegenerative diseases are the impermeability of the blood-brain barrier to many therapeutic agents and difficulties in reversing brain damage that has already occurred. This article focuses on how cholesterol balance in the brain is altered in several neurodegenerative diseases, and discusses some commonalities and differences among the diseases.
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Affiliation(s)
- Jean E Vance
- Group on the Molecular and Cell Biology of Lipids and Department of Medicine, University of Alberta, Edmonton, AB, T6G 2S2, Canada.
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18
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Bi X, Han X, Zhang F, He M, Zhang Y, Zhi XY, Zhao H. Triparanol suppresses human tumor growth in vitro and in vivo. Biochem Biophys Res Commun 2012; 425:613-8. [PMID: 22877755 DOI: 10.1016/j.bbrc.2012.07.136] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 07/24/2012] [Indexed: 12/28/2022]
Abstract
Despite the improved contemporary multidisciplinary regimens treating cancer, majority of cancer patients still suffer from adverse effects and relapse, therefore posing a significant challenge to uncover more efficacious molecular therapeutics targeting signaling pathways central to tumorigenesis. Here, our study have demonstrated that Triparanol, a cholesterol synthesis inhibitor, can block proliferation and induce apoptosis in multiple human cancer cells including lung, breast, liver, pancreatic, prostate cancer and melanoma cells, and growth inhibition can be rescued by exogenous addition of cholesterol. Remarkably, we have proved Triparanol can significantly repress Hedgehog pathway signaling in these human cancer cells. Furthermore, study in a mouse xenograft model of human lung cancer has validated that Triparanol can impede tumor growth in vivo. We have therefore uncovered Triparanol as potential new cancer therapeutic in treating multiple types of human cancers with deregulated Hedgehog signaling.
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Affiliation(s)
- Xinyu Bi
- Department of Abdominal Surgical Oncology, Lab of Abdominal Surgical Oncology, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
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19
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Hymel D, Peterson BR. Synthetic cell surface receptors for delivery of therapeutics and probes. Adv Drug Deliv Rev 2012; 64:797-810. [PMID: 22401875 PMCID: PMC3359398 DOI: 10.1016/j.addr.2012.02.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 02/18/2012] [Accepted: 02/20/2012] [Indexed: 11/17/2022]
Abstract
Receptor-mediated endocytosis is a highly efficient mechanism for cellular uptake of membrane-impermeant ligands. Cells use this process to acquire nutrients, initiate signal transduction, promote development, regulate neurotransmission, and maintain homeostasis. Natural receptors that participate in receptor-mediated endocytosis are structurally diverse, ranging from large transmembrane proteins to small glycolipids embedded in the outer leaflet of cellular plasma membranes. Despite their vast structural differences, these receptors share common features of binding to extracellular ligands, clustering in dynamic membrane regions that pinch off to yield intracellular vesicles, and accumulation of receptor-ligand complexes in membrane-sealed endosomes. Receptors typically dissociate from ligands in endosomes and cycle back to the cell surface, whereas internalized ligands are usually delivered into lysosomes, where they are degraded, but some can escape and penetrate into the cytosol. Here, we review efforts to develop synthetic cell surface receptors, defined as nonnatural compounds, exemplified by mimics of cholesterol, that insert into plasma membranes, bind extracellular ligands including therapeutics, probes, and endogenous proteins, and engage endocytic membrane trafficking pathways. By mimicking natural mechanisms of receptor-mediated endocytosis, synthetic cell surface receptors have the potential to function as prosthetic molecules capable of seamlessly augmenting the endocytic uptake machinery of living mammalian cells.
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Affiliation(s)
- David Hymel
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS 66045, United States
| | - Blake R. Peterson
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS 66045, United States
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20
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Soleti R, Martinez MC. Sonic Hedgehog on microparticles and neovascularization. VITAMINS AND HORMONES 2012; 88:395-438. [PMID: 22391314 DOI: 10.1016/b978-0-12-394622-5.00018-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neovascularization represents a pivotal process consisting in the development of vascular network during embryogenesis and adult life. Postnatally, it arises mainly through angiogenesis, which has physiological and pathological roles in health and disease. Blood vessel formation results as tightly regulated multistep process which needs coordination and precise regulation of the balance of proangiogenic and antiangiogenic factors. Sonic Hedgehog (SHH), a morphogen belonging to Hedgehog (HH) family proteins, is implicated in a remarkably wide variety of process, including vessel development. Recent evidence demonstrate that, in addition to the classic factors, microvesicles (MVs), both microparticles (MPs) and exosomes, small vesicles released distinct cellular compartments, are involved in modulation of neovascularization. MPs generated from T lymphocytes undergoing both activation and apoptosis harbor at their surface SHH and play a crucial role in modulation of neovascularization. They are able to modulate the different steps implicated in angiogenesis process in vitro and to enhance postischemic neovascularization in vivo. As the consequence, we suggest that the MPs carrying SHH contribute to generation of a vascular network and may represent a new therapeutic approach to treat pathologies associated with failed angiogenesis.
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21
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Belter A, Skupinska M, Giel-Pietraszuk M, Grabarkiewicz T, Rychlewski L, Barciszewski J. Squalene monooxygenase – a target for hypercholesterolemic therapy. Biol Chem 2011; 392:1053-75. [DOI: 10.1515/bc.2011.195] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Squalene monooxygenase catalyzes the epoxidation of C-C double bond of squalene to yield 2,3-oxidosqualene, the key step of sterol biosynthesis pathways in eukaryotes. Sterols are essential compounds of these organisms and squalene epoxidation is an important regulatory point in their synthesis. Squalene monooxygenase downregulation in vertebrates and fungi decreases synthesis of cholesterol and ergosterol, respectively, which makes squalene monooxygenase a potent and attractive target of hypercholesterolemia and antifungal therapies. Currently some fungal squalene monooxygenase inhibitors (terbinafine, naftifine, butenafine) are in clinical use, whereas mammalian enzymes’ inhibitors are still under investigation. Research on new squalene monooxygenase inhibitors is important due to the prevalence of hypercholesterolemia and the lack of both sufficient and safe remedies. In this paper we (i) review data on activity and the structure of squalene monooxygenase, (ii) present its inhibitors, (iii) compare current strategies of lowering cholesterol level in blood with some of the most promising strategies, (iv) underline advantages of squalene monooxygenase as a target for hypercholesterolemia therapy, and (v) discuss safety concerns about hypercholesterolemia therapy based on inhibition of cellular cholesterol biosynthesis and potential usage of squalene monooxygenase inhibitors in clinical practice. After many years of use of statins there is some clinical evidence for their adverse effects and only partial effectiveness. Currently they are drugs of choice but are used with many restrictions, especially in case of children, elderly patients and women of childbearing potential. Certainly, for the next few years, statins will continue to be a suitable tool for cost-effective cardiovascular prevention; however research on new hypolipidemic drugs is highly desirable. We suggest that squalene monooxygenase inhibitors could become the hypocholesterolemic agents of the future.
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22
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Belter A, Skupinska M, Giel-Pietraszuk M, Grabarkiewicz T, Rychlewski L, Barciszewski J. Squalene monooxygenase - a target for hypercholesterolemic therapy. Biol Chem 2011. [PMID: 22050222 DOI: 10.1515/bc-2011-195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Squalene monooxygenase catalyzes the epoxidation of C-C double bond of squalene to yield 2,3-oxidosqualene, the key step of sterol biosynthesis pathways in eukaryotes. Sterols are essential compounds of these organisms and squalene epoxidation is an important regulatory point in their synthesis. Squalene monooxygenase downregulation in vertebrates and fungi decreases synthesis of cholesterol and ergosterol, respectively, which makes squalene monooxygenase a potent and attractive target of hypercholesterolemia and antifungal therapies. Currently some fungal squalene monooxygenase inhibitors (terbinafine, naftifine, butenafine) are in clinical use, whereas mammalian enzymes' inhibitors are still under investigation. Research on new squalene monooxygenase inhibitors is important due to the prevalence of hypercholesterolemia and the lack of both sufficient and safe remedies. In this paper we (i) review data on activity and the structure of squalene monooxygenase, (ii) present its inhibitors, (iii) compare current strategies of lowering cholesterol level in blood with some of the most promising strategies, (iv) underline advantages of squalene monooxygenase as a target for hypercholesterolemia therapy, and (v) discuss safety concerns about hypercholesterolemia therapy based on inhibition of cellular cholesterol biosynthesis and potential usage of squalene monooxygenase inhibitors in clinical practice. After many years of use of statins there is some clinical evidence for their adverse effects and only partial effectiveness. Currently they are drugs of choice but are used with many restrictions, especially in case of children, elderly patients and women of childbearing potential. Certainly, for the next few years, statins will continue to be a suitable tool for cost-effective cardiovascular prevention; however research on new hypolipidemic drugs is highly desirable. We suggest that squalene monooxygenase inhibitors could become the hypocholesterolemic agents of the future.
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Affiliation(s)
- Agnieszka Belter
- Institute of Bioorganic Chemistry, Polish Academy of Science, Noskowskiego 12/14, 61-704 Poznan, Poland
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23
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Rawlings ND, Barrett AJ, Bateman A. Asparagine peptide lyases: a seventh catalytic type of proteolytic enzymes. J Biol Chem 2011; 286:38321-38328. [PMID: 21832066 PMCID: PMC3207474 DOI: 10.1074/jbc.m111.260026] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The terms “proteolytic enzyme” and “peptidase” have been treated as synonymous, and all proteolytic enzymes have been considered to be hydrolases (EC 3.4). However, the recent discovery of proteins that cleave themselves at asparagine residues indicates that not all peptide bond cleavage occurs by hydrolysis. These self-cleaving proteins include the Tsh protein precursor of Escherichia coli, in which the large C-terminal propeptide acts as an autotransporter; certain viral coat proteins; and proteins containing inteins. Proteolysis is the action of an amidine lyase (EC 4.3.2). These proteolytic enzymes are also the first in which the nucleophile is an asparagine, defining the seventh proteolytic catalytic type and the first to be discovered since 2004. We have assembled ten families based on sequence similarity in which cleavage is thought to be catalyzed by an asparagine.
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Affiliation(s)
- Neil David Rawlings
- Wellcome Trust Genome Campus, The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, United Kingdom.
| | - Alan John Barrett
- Wellcome Trust Genome Campus, The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, United Kingdom
| | - Alex Bateman
- Wellcome Trust Genome Campus, The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, United Kingdom
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24
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The desmosterolosis phenotype: spasticity, microcephaly and micrognathia with agenesis of corpus callosum and loss of white matter. Eur J Hum Genet 2011; 19:942-6. [PMID: 21559050 DOI: 10.1038/ejhg.2011.74] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Desmosterolosis is a rare autosomal recessive disorder of elevated levels of the cholesterol precursor desmosterol in plasma, tissue and cultured cells. With only two sporadic cases described to date with two very different phenotypes, the clinical entity arising from mutations in 24-dehydrocholesterol reductase (DHCR24) has yet to be defined. We now describe consanguineous Bedouin kindred with four surviving affected individuals, all presenting with severe failure to thrive, psychomotor retardation, microcephaly, micrognathia and spasticity with variable degree of hand contractures. Convulsions near birth, nystagmus and strabismus were found in most. Brain MRI demonstrated significant reduction in white matter and near agenesis of corpus callosum in all. Genome-wide linkage analysis and fine mapping defined a 6.75 cM disease-associated locus in chromosome 1 (maximum multipoint LOD score of six), and sequencing of candidate genes within this locus identified in the affected individuals a homozygous missense mutation in DHCR24 leading to dramatically augmented plasma desmosterol levels. We thus establish a clear consistent phenotype of desmosterolosis (MIM 602398).
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25
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Martin DDO, Beauchamp E, Berthiaume LG. Post-translational myristoylation: Fat matters in cellular life and death. Biochimie 2011; 93:18-31. [PMID: 21056615 DOI: 10.1016/j.biochi.2010.10.018] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 10/23/2010] [Indexed: 01/15/2023]
Abstract
Myristoylation corresponds to the irreversible covalent linkage of the 14-carbon saturated fatty acid, myristic acid, to the N-terminal glycine of many eukaryotic and viral proteins. It is catalyzed by N-myristoyltransferase. Typically, the myristate moiety participates in protein subcellular localization by facilitating protein-membrane interactions as well as protein-protein interactions. Myristoylated proteins are crucial components of a wide variety of functions, which include many signalling pathways, oncogenesis or viral replication. Initially, myristoylation was described as a co-translational reaction that occurs after the removal of the initiator methionine residue. However, it is now well established that myristoylation can also occur post-translationally in apoptotic cells. Indeed, during apoptosis hundreds of proteins are cleaved by caspases and in many cases this cleavage exposes an N-terminal glycine within a cryptic myristoylation consensus sequence, which can be myristoylated. The principal objective of this review is to provide an overview on the implication of myristoylation in health and disease with a special emphasis on post-translational myristoylation. In addition, new advancements in the detection and identification of myristoylated proteins are also briefly reviewed.
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Affiliation(s)
- Dale D O Martin
- Department of Cell Biology, School of Molecular and Systems Medicine, MSB-5-55, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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26
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Lee SY, Choi HK, Kim ST, Chung S, Park MK, Cho JH, Ho WK, Cho H. Cholesterol inhibits M-type K+ channels via protein kinase C-dependent phosphorylation in sympathetic neurons. J Biol Chem 2010; 285:10939-50. [PMID: 20123983 PMCID: PMC2856299 DOI: 10.1074/jbc.m109.048868] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 01/25/2010] [Indexed: 01/10/2023] Open
Abstract
M-type (KCNQ) potassium channels play an important role in regulating the action potential firing in neurons. Here, we investigated the effect of cholesterol on M current in superior cervical ganglion (SCG) sympathetic neurons, using the patch clamp technique. M current was inhibited in a dose-dependent manner by cholesterol loading with a methyl-beta-cyclodextrin-cholesterol complex. This effect was prevented when membrane cholesterol level was restored by including empty methyl-beta-cyclodextrin in the pipette solution. Dialysis of cells with AMP-PNP instead of ATP prevented cholesterol action on M currents. Protein kinase C (PKC) inhibitor, calphostin C, abolished cholesterol-induced inhibition whereas the PKC activator, PDBu, mimicked the inhibition of M currents by cholesterol. The in vitro kinase assay showed that KCNQ2 subunits of M channel can be phosphorylated by PKC. A KCNQ2 mutant that is defective in phosphorylation by PKC failed to show current inhibition not only by PDBu but also by cholesterol. These results indicate that cholesterol-induced inhibition of M currents is mediated by PKC phosphorylation. The inhibition of M currents by PDBu and cholesterol was completely blocked by PIP(2) loading, indicating that the decrease in PIP(2)-channel interaction underlies M channel inhibition by PKC-mediated phosphorylation. We conclude that cholesterol specifically regulates M currents in SCG neurons via PKC activation.
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Affiliation(s)
| | - Hyun-Kyung Choi
- Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and
| | - Seong-Tae Kim
- Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and
| | | | | | - Jung-Hwa Cho
- the WCU Neurocytomics Program Project, Department of Physiology, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul 110-799, Korea
| | - Won-Kyung Ho
- the WCU Neurocytomics Program Project, Department of Physiology, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul 110-799, Korea
| | - Hana Cho
- From the Departments of Physiology and
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27
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Haas D, Muenke M. Abnormal sterol metabolism in holoprosencephaly. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2010; 154C:102-8. [PMID: 20104605 DOI: 10.1002/ajmg.c.30243] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Holoprosencephaly (HPE) is the most common structural malformation of the developing forebrain in humans. The HPE phenotype is extremely variable and the etiology is heterogeneous. Among a variety of embryological toxins that can induce HPE, inhibitors, and other pertubations of cholesterol biosynthesis have been shown to be important factors, most likely because cholesterol is required in the Sonic hedgehog signaling cascade. Decreased levels of maternal cholesterol during pregnancy increase the risk for preterm delivery, but they are not associated with congenital malformations. However, if the fetus is affected by an inborn error of endogenous cholesterol synthesis, a reduction of maternal cholesterol concentration and cholesterol transport over the placenta aggravates the phenotypic expression. Exposure to lipophilic statins in early pregnancy may be associated with a substantial risk for structural CNS defects.
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Affiliation(s)
- Dorothea Haas
- University Children's Hospital of Heidelberg, Germany.
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28
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Mao H, Diehl AM, Li YX. Sonic hedgehog ligand partners with caveolin-1 for intracellular transport. J Transl Med 2009; 89:290-300. [PMID: 19139721 PMCID: PMC2647995 DOI: 10.1038/labinvest.2008.163] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Prenatal alcohol exposure is the most common environmental factor leading to congenital birth defects in the United States. Although significant progress has been made in this field, the detailed molecular pathology of fetal alcohol syndrome (FAS) remains to be determined. Previously, we have shown that alcohol exposure perturbs hedgehog signal transduction in zebrafish embryos by inhibiting the post-translational cholesterol modification of Sonic hedgehog (Shh), leading to decreased levels of mature Shh ligand that is associated with the plasma membrane, and causing transient loss of Hh signaling, resulting in permanent FAS-related morphological abnormalities. In the present study, we further elucidate the mechanisms that regulate the intracellular transportation and secretion of Shh using the hepatic stellate cell line HSC8B. We have found that Shh is associated with caveolin-1 in the Golgi apparatus to form protein complexes and that these complexes are packaged as large punctuate structures (transport vesicles) that are transported to the plasma membrane in lipid raft microdomains. Alcohol exposure does not significantly interrupt translation of shh mRNA in endoplasmic reticulum (ER) or the trafficking of Shh from the ER to the Golgi apparatus. However, alcohol does prevent the entry of Shh into transport vesicles from the Golgi to the plasma membrane and specifically decreases the amount of caveolin-1/Shh complex found in lipid rafts, causing cytoplasmic accumulation of Shh and leading to a deficiency of Shh ligand secretion into the extracellular matrix.
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Affiliation(s)
- Hua Mao
- Division of Gastroenterology and Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Anna Mae Diehl
- Division of Gastroenterology and Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Yin-Xiong Li
- Division of Gastroenterology and Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.,Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710, USA
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29
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Hackenberger C, Schwarzer D. Chemoselektive Ligations- und Modifikationsstrategien für Peptide und Proteine. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801313] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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30
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Hackenberger C, Schwarzer D. Chemoselective Ligation and Modification Strategies for Peptides and Proteins. Angew Chem Int Ed Engl 2008; 47:10030-74. [DOI: 10.1002/anie.200801313] [Citation(s) in RCA: 651] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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van Straten EME, Huijkman NCA, Baller JFW, Kuipers F, Plösch T. Pharmacological activation of LXR in utero directly influences ABC transporter expression and function in mice but does not affect adult cholesterol metabolism. Am J Physiol Endocrinol Metab 2008; 295:E1341-8. [PMID: 18840761 DOI: 10.1152/ajpendo.90597.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholesterol is critical for several cellular functions and essential for normal fetal development. Therefore, its metabolism is tightly controlled during all life stages. The liver X receptors-alpha (LXRalpha; NR1H3) and -beta (LXRbeta; NR1H2) are nuclear receptors that are of key relevance in coordinating cholesterol and fatty acid metabolism. The aim of this study was to elucidate whether fetal cholesterol metabolism can be influenced in utero via pharmacological activation of LXR and whether this would have long-term effects on cholesterol homeostasis. Administration of the LXR agonist T0901317 to pregnant mice via their diet (0.015% wt/wt) led to induced fetal hepatic expression levels of the cholesterol transporter genes Abcg5/g8 and Abca1, higher plasma cholesterol levels, and lower hepatic cholesterol levels compared with controls. These profound changes during fetal development did not affect cholesterol metabolism in adulthood nor did they influence coping with a high-fat/high-cholesterol diet. This study shows that the LXR system is functional in fetal mice and susceptible to pharmacological activation. Despite massive changes in fetal cholesterol metabolism, regulatory mechanisms involved in cholesterol metabolism return to a "normal" state in offspring and allow coping with a high-fat/high-cholesterol diet.
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Affiliation(s)
- E M E van Straten
- Dept. of Pediatrics, Univ. Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen
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32
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Babin PJ, Gibbons GF. The evolution of plasma cholesterol: direct utility or a "spandrel" of hepatic lipid metabolism? Prog Lipid Res 2008; 48:73-91. [PMID: 19049814 DOI: 10.1016/j.plipres.2008.11.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 11/06/2008] [Accepted: 11/07/2008] [Indexed: 02/07/2023]
Abstract
Fats provide a concentrated source of energy for multicellular organisms. The efficient transport of fats through aqueous biological environments raises issues concerning effective delivery to target tissues. Furthermore, the utilization of fatty acids presents a high risk of cytotoxicity. Improving the efficiency of fat transport while simultaneously minimizing the cytotoxic risk confers distinct selective advantages. In humans, most of the plasma cholesterol is associated with low-density lipoprotein (LDL), a metabolic by-product of very-low-density lipoprotein (VLDL), which originates in the liver. However, the functions of VLDL are not clear. This paper reviews the evidence that LDL arose as a by-product during the natural selection of VLDL. The latter, in turn, evolved as a means of improving the efficiency of diet-derived fatty acid storage and utilization, as well as neutralizing the potential cytotoxicity of fatty acids while conserving their advantages as a concentrated energy source. The evolutionary biology of lipid transport processes has provided a fascinating insight into how and why these VLDL functions emerged during animal evolution. As causes of historical origin must be separated from current utilities, our spandrel-LDL theory proposes that LDL is a spandrel of VLDL selection, which appeared non-adaptively and may later have become crucial for vertebrate fitness.
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Affiliation(s)
- Patrick J Babin
- Université Bordeaux 1, Génomique et Physiologie des Poissons, UMR NuAGe, 33405 Talence, France
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33
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Parada C, Escolà-Gil JC, Bueno D. Low-density lipoproteins from embryonic cerebrospinal fluid are required for neural differentiation. J Neurosci Res 2008; 86:2674-84. [DOI: 10.1002/jnr.21724] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Vinci G, Xia X, Veitia RA. Preservation of genes involved in sterol metabolism in cholesterol auxotrophs: facts and hypotheses. PLoS One 2008; 3:e2883. [PMID: 18682733 PMCID: PMC2478713 DOI: 10.1371/journal.pone.0002883] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 07/11/2008] [Indexed: 12/02/2022] Open
Abstract
Background It is known that primary sequences of enzymes involved in sterol biosynthesis are well conserved in organisms that produce sterols de novo. However, we provide evidence for a preservation of the corresponding genes in two animals unable to synthesize cholesterol (auxotrophs): Drosophila melanogaster and Caenorhabditis elegans. Principal Findings We have been able to detect bona fide orthologs of several ERG genes in both organisms using a series of complementary approaches. We have detected strong sequence divergence between the orthologs of the nematode and of the fruitfly; they are also very divergent with respect to the orthologs in organisms able to synthesize sterols de novo (prototrophs). Interestingly, the orthologs in both the nematode and the fruitfly are still under selective pressure. It is possible that these genes, which are not involved in cholesterol synthesis anymore, have been recruited to perform different new functions. We propose a more parsimonious way to explain their accelerated evolution and subsequent stabilization. The products of ERG genes in prototrophs might be involved in several biological roles, in addition to sterol synthesis. In the case of the nematode and the fruitfly, the relevant genes would have lost their ancestral function in cholesterogenesis but would have retained the other function(s), which keep them under pressure. Conclusions By exploiting microarray data we have noticed a strong expressional correlation between the orthologs of ERG24 and ERG25 in D. melanogaster and genes encoding factors involved in intracellular protein trafficking and folding and with Start1 involved in ecdysteroid synthesis. These potential functional connections are worth being explored not only in Drosophila, but also in Caenorhabditis as well as in sterol prototrophs.
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Affiliation(s)
- Giovanna Vinci
- Institut Cochin, Département de Génétique et Développement. Inserm, U567, CNRS, UMR 8104, Université Paris 5, Faculté de Médecine Paris Descartes, UM 3, Paris, France
| | - Xuhua Xia
- CAREG and Biology Department, University of Ottawa, Ottawa, Ontario, Canada
| | - Reiner A. Veitia
- Institut Cochin, Département de Génétique et Développement. Inserm, U567, CNRS, UMR 8104, Université Paris 5, Faculté de Médecine Paris Descartes, UM 3, Paris, France
- Université Denis Diderot/Paris VII, Paris, France
- * E-mail:
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35
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Bate C, Williams A. Do prion-induced changes in membrane cholesterol trigger neurodegeneration? FUTURE NEUROLOGY 2008. [DOI: 10.2217/14796708.3.4.367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Clive Bate
- Royal Veterinary College, Department of Pathology and Infectious Diseases, Hawkshead, Hertfordshire, AL9 7TA, UK
| | - Alun Williams
- Royal Veterinary College, Department of Pathology and Infectious Diseases, Hawkshead, Hertfordshire, AL9 7TA, UK
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36
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Edison R, Muenke M. The interplay of genetic and environmental factors in craniofacial morphogenesis: holoprosencephaly and the role of cholesterol. Clin Genet 2008. [DOI: 10.1111/j.1399-0004.2003.tb02302.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Javitt NB. Oxysterols: novel biologic roles for the 21st century. Steroids 2008; 73:149-57. [PMID: 18068744 DOI: 10.1016/j.steroids.2007.10.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 09/17/2007] [Accepted: 10/12/2007] [Indexed: 01/17/2023]
Abstract
A major focus for the 21st century are the sterol intermediates in cholesterol synthesis and their metabolites. No longer considered inactive way stations in their transformation to cholesterol, both physiologic and pathophysiologic studies, though early in their development, indicate novel biologic roles for these sterols, and their oxysterol metabolites that bypass cholesterol, the expected end product. A major impetus for further inquiry is the recognition that in genetically determined errors in cholesterol synthesis such as Smith-Lemil-Opitz syndrome, the phenotypic effects on the developing fetus are not solely attributable to the lack of cholesterol but the accumulation of 7-dehydrocholesterol and its 27-hydroxy metabolite. This view is now supported by a new mouse model, the double knockout Insig1 & 2 (insulin-induced genes 1 & 2) in which lack of the protein product results in a greater production of lanosterol compared to cholesterol during fetal life with severe dysmorphic consequences. Further support can be derived from in vitro studies of the Sonic hedgehog signaling pathway, essential for normal morphogenesis in the central nervous system and perhaps other organs, which may require the local presence of oxysterols for full expression. Future studies that can delineate the specific role of a sterol intermediate or its metabolite require a paradigm shift away from the generic use of oxysterols as a class of compounds to a focus on specific sterols that can be expected in tissues and techniques for mimicking the local environment. Another class of oxysterols are those arising by photoxidation, now considered to be an expected event generated by the photons of visible blue light and therefore pari passu with normal vision. The sequence of events from peroxides of cholesterol to hydroxy and keto derivatives is the signature of singlet oxygen as opposed to free radicals and other mechanisms for generating reactive oxygen species. Perhaps surprisingly, the retina expresses CYP 27A1 and CYP 46A1, enzymes with broad substrate specificity for ring-modified sterols, implying that, in addition to a rich blood supply for disposing of potentially toxic oxysterols, they can be detoxified locally. Recognition that the retina has nuclear receptors similar to those found in other tissues raises the possibility that the sterols that are generated may function in their traditional role as ligands for modulating gene expression but other, nonligand, activities can be expected since other proteins such as the oxysterol-binding proteins exist and are considered to have biologic activities. To critically evaluate these potentially new biologic roles for oxysterols a need exists for the synthesis and utilization of the expected naturally occurring metabolites rather than available surrogates that may not be truly representative of their tissue effects and to utilize analytical techniques that can identify their existence at the expected concentrations in tissues.
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Affiliation(s)
- Norman B Javitt
- Department of Pediatrics and Medicine, NYU School of Medicine, 550 First Avenue, New York, NY 10016, United States.
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38
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Hao L, Mukherjee K, Liegeois S, Baillie D, Labouesse M, Bürglin TR. The hedgehog-related gene qua-1 is required for molting in Caenorhabditis elegans. Dev Dyn 2007; 235:1469-81. [PMID: 16502424 DOI: 10.1002/dvdy.20721] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Caenorhabditis elegans genome encodes ten proteins that share similarity with Hedgehog through the C-terminal Hint/Hog domain. While most genes are members of larger gene families, qua-1 is a single copy gene. Here we show that orthologs of qua-1 exist in many nematodes, including Brugia malayi, which shared a common ancestor with C. elegans about 300 million years ago. The QUA-1 proteins contain an N-terminal domain, the Qua domain, that is highly conserved, but whose molecular function is not known. We have studied the expression pattern of qua-1 in C. elegans using a qua-1::GFP transcriptional fusion. qua-1 is mainly expressed in hyp1 to hyp11 hypodermal cells, but not in seam cells. It is also expressed in intestinal and rectal cells, sensilla support cells, and the P cell lineage in L1. The expression of qua-1::GFP undergoes cyclical changes during development in phase with the molting cycle. It accumulates prior to molting and disappears between molts. Disruption of the qua-1 gene function through an internal deletion that causes a frame shift with premature stop in the middle of the gene results in strong lethality. The animals arrest in the early larval stages due to defects in molting. Electron microscopy reveals double cuticles due to defective ecdysis, but no obvious defects are seen in the hypodermis. Qua domain-only::GFP and full-length QUA-1::GFP fusion constructs are secreted and associated with the overlying cuticle, but only QUA-1::GFP rescues the mutant phenotype. Our results suggest that both the Hint/Hog domain and Qua domain are critically required for the function of QUA-1.
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Affiliation(s)
- Limin Hao
- Department of Biosciences and Nutrition, and Center for Genomics and Bioinformatics, Karolinska Institutet, Huddinge, Sweden
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39
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Rawlings ND, Morton FR. The MEROPS batch BLAST: a tool to detect peptidases and their non-peptidase homologues in a genome. Biochimie 2007; 90:243-59. [PMID: 17980477 DOI: 10.1016/j.biochi.2007.09.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 09/21/2007] [Indexed: 11/29/2022]
Abstract
Many of the 181 families of peptidases contain homologues that are known to have functions other than peptide bond hydrolysis. Distinguishing an active peptidase from a homologue that is not a peptidase requires specialist knowledge of the important active site residues, because replacement or lack of one of these catalytic residues is an important clue that the homologue in question is unlikely to hydrolyse peptide bonds. Now that the rate at which proteins are characterized is outstripped by the rate that genome sequences are determined, many genes are being incorrectly annotated because only sequence similarity is taken into consideration. We present a tool called the MEROPS batch BLAST which not only performs a comparison against the MEROPS sequence collection, but also does a pair-wise alignment with the closest homologue detected and calculates the position of the active site residues. A non-peptidase homologue can be distinguished by the absence or unacceptable replacement of any of these residues. An analysis of peptidase homologues in the genome of the bacterium Erythrobacter litoralis is presented as an example.
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Affiliation(s)
- Neil D Rawlings
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK.
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40
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Li YX, Yang HT, Zdanowicz M, Sicklick JK, Qi Y, Camp TJ, Diehl AM. Fetal alcohol exposure impairs Hedgehog cholesterol modification and signaling. J Transl Med 2007; 87:231-40. [PMID: 17237799 DOI: 10.1038/labinvest.3700516] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Consumption of alcohol by pregnant women can cause fetal alcohol spectrum defects (FASD), a congenital disease, which is characterized by an array of developmental defects that include neurological, craniofacial, cardiac, and limb malformations, as well as generalized growth retardation. FASD remains a significant clinical challenge and an important social problem. Although there has been great progress in delineating the mechanisms contributing to alcohol-induced birth defects, gaps in our knowledge still remain; for instance, why does alcohol preferentially induce a spectrum of defects in specific organs and why is the spectrum of defects reproducible and predictable. In this study, we show that exposure of zebrafish embryos to low levels of alcohol during gastrulation blocks covalent modification of Sonic hedgehog by cholesterol. This leads to impaired Hh signal transduction and results in a dose-dependent spectrum of permanent developmental defects that closely resemble FASD. Furthermore, supplementing alcohol-exposed embryos with cholesterol rescues the loss of Shh signal transduction, and prevents embryos from developing FASD-like morphologic defects. Overall, we have shown that a simple post-translational modification defect in a key morphogen may contribute to an environmentally induced complex congenital syndrome. This insight into FASD pathogenesis may suggest novel strategies for preventing these common congenital defects.
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Affiliation(s)
- Yin-Xiong Li
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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41
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Oriá RB, Patrick PD, Blackman JA, Lima AAM, Guerrant RL. Role of apolipoprotein E4 in protecting children against early childhood diarrhea outcomes and implications for later development. Med Hypotheses 2006; 68:1099-107. [PMID: 17098371 PMCID: PMC3993898 DOI: 10.1016/j.mehy.2006.09.036] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Accepted: 09/14/2006] [Indexed: 11/18/2022]
Abstract
Our group and others have reported a series of studies showing that heavy burdens of diarrheal diseases in the formative first two years of life in children in urban shantytowns have profound consequences of impaired physical and cognitive development lasting into later childhood and schooling. Based on these previous studies showing that apolipoprotein E4 (APOE4) is relatively common in favela children, we review recent data suggesting a protective role for the APOE4 allele in the cognitive and physical development of children with heavy burdens of diarrhea in early childhood. Despite being a marker for cognitive decline with Alzheimer's and cardiovascular diseases later in life, APOE4 appears to be important for cognitive development under the stress of heavy diarrhea. The reviewed findings provide a potential explanation for the survival advantage in evolution of the thrifty APOE4 allele and raise questions about its implications for human development under life-style changes and environmental challenges.
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Affiliation(s)
- Reinaldo B Oriá
- Center for Global Health, School of Medicine, University of Virginia, United States.
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42
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Tadjuidje E, Hollemann T. Cholesterol homeostasis in development: the role of Xenopus 7-dehydrocholesterol reductase (Xdhcr7) in neural development. Dev Dyn 2006; 235:2095-110. [PMID: 16752377 DOI: 10.1002/dvdy.20860] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
7-dehydrocholesterol reductase (7-Dhcr) catalyses the final step in the pathway of cholesterol biosynthesis. Human patients with inborn errors of 7-Dhcr (Smith-Lemli-Opitz-Syndrome) have elevated serum levels of 7-dehydrocholesterol but low levels of cholesterol, which in phenotypical terms can result in growth retardation, craniofacial abnormalities including cleft palate, and reduced metal abilities. This study reports the isolation and molecular characterisation of 7-dehydrocholesterol reductase (Xdhcr7) from Xenopus laevis. During early embryonic development, the expression of Xdhcr7 is first of all spatially restricted to the Spemann's organizer and later to the notochord. In both tissues, Xdhcr7 is coexpressed with Sonic hedgehog (Shh), which itself is cholesterol-modified during autoproteolytic cleavage. Data from Xdhcr7 overexpression and knockdown experiments reveals that a tight control of cholesterol synthesis is particularly important for proper development of the central and peripheral nervous system.
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Affiliation(s)
- Emmanuel Tadjuidje
- University of Halle-Wittenberg, Institut für Physiologische Chemie, Halle/Saale, Germany
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43
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Snell EA, Brooke NM, Taylor WR, Casane D, Philippe H, Holland PW. An unusual choanoflagellate protein released by Hedgehog autocatalytic processing. Proc Biol Sci 2006; 273:401-7. [PMID: 16615205 PMCID: PMC1560198 DOI: 10.1098/rspb.2005.3263] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Hedgehog proteins are important cell-cell signalling proteins utilized during the development of multicellular animals. Members of the hedgehog gene family have not been detected outside the Metazoa, raising unanswered questions about their evolutionary origin. Here we report a highly unusual hedgehog-related gene from a choanoflagellate, a close unicellular relative of the animals. The deduced C-terminal domain, Hoglet-C, is homologous to the autocatalytic domain of Hedgehog proteins and is predicted to function in autocatalytic cleavage of the precursor peptide. In contrast, the N-terminal Hoglet-N peptide has no similarity to the signalling peptide of Hedgehog (Hh-N). Instead, Hoglet-N is deduced to be a secreted protein with an enormous threonine-rich domain of unprecedented size and purity (over 200 threonine residues) and two polysaccharide-binding domains. Structural modelling reveals that these domains have a novel combination of features found in cellulose-binding domains (CBD) of types IIa and IIb, and are expected to bind cellulose. We propose that the two CBD domains enable Hoglet-N to bind to plant matter, tethering an amorphous nucleophilic anchor, facilitating transient adhesion of the choanoflagellate cell. Since Hh-C and Hoglet-C are homologous, but Hh-N and Hoglet-N are not, we argue that metazoan hedgehog genes evolved by fusion of two distinct genes.
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Affiliation(s)
- Elizabeth A Snell
- School of Animal and Microbial Sciences The University of ReadingWhiteknights, Reading RG6 6AJ, UK
- Department of Biology North Carolina A&T State UniversityGreensboro, NC 27411, USA
| | - Nina M Brooke
- School of Animal and Microbial Sciences The University of ReadingWhiteknights, Reading RG6 6AJ, UK
- Department of Zoology University of OxfordSouth Parks Road, Oxford OX1 3PS, UK
- School of Continuing Education The University of ReadingLondon Road, Reading RG1 5AQ, UK
| | - William R Taylor
- The National Institute for Medical ResearchThe Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Didier Casane
- Phylogénie, Bioinformatique et Génome, UMR 7622 CNRS Université Pierre et Marie Curie9 quai St Bernard Bât. C, 75005 Paris, France
- Populations, Genetique et EvolutionUPR9034, CNRS, 91198 Gif-sur-Yvette, France
| | - Hervé Philippe
- Phylogénie, Bioinformatique et Génome, UMR 7622 CNRS Université Pierre et Marie Curie9 quai St Bernard Bât. C, 75005 Paris, France
- Département de Biochimie Université de MontréalSuccursale Centre-Ville, Montréal, Québec H3C3J7, Canada
| | - Peter W.H Holland
- Department of Zoology University of OxfordSouth Parks Road, Oxford OX1 3PS, UK
- Author for correspondence ()
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Zamir O, Charlton MP. Cholesterol and synaptic transmitter release at crayfish neuromuscular junctions. J Physiol 2005; 571:83-99. [PMID: 16339182 PMCID: PMC1805643 DOI: 10.1113/jphysiol.2005.098319] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
During exocytosis of synaptic transmitters, the fusion of highly curved synaptic vesicle membranes with the relatively planar cell membrane requires the coordinated action of several proteins. The role of membrane lipids in the regulation of transmitter release is less well understood. Since it helps to control membrane fluidity, alteration of cholesterol content may alter the fusibility of membranes as well as the function of membrane proteins. We assayed the importance of cholesterol in transmitter release at crayfish neuromuscular junctions where action potentials can be measured in the preterminal axon. Methyl-beta-cyclodextrin (MbetaCD) depleted axons of cholesterol, as shown by reduced filipin labelling, and cholesterol was replenished by cholesterol-MbetaCD complex (Ch-MbetaCD). MbetaCD blocked evoked synaptic transmission. The lack of postsynaptic effects of MbetaCD on the time course and amplitude of spontaneous postsynaptic potentials or on muscle resting potential allowed us to focus on presynaptic mechanisms. Intracellular presynaptic axon recordings and focal extracellular recordings at individual boutons showed that failure of transmitter release was correlated with presynaptic hyperpolarization and failure of action potential propagation. All of these effects were reversed when cholesterol was replenished with Ch-MbetaCD. However, focal depolarization of presynaptic boutons and administration of a Ca2+ ionophore both triggered transmitter release after cholesterol depletion. Therefore, both presynaptic Ca2+ channels and Ca2+-dependent exocytosis functioned after cholesterol depletion. The frequency of spontaneous quantal transmitter release was increased by MbetaCD but recovered when cholesterol was reintroduced. The increase in spontaneous release was not through a calcium-dependent mechanism because it persisted with intense intracellular calcium chelation. In conclusion, cholesterol levels in the presynaptic membrane modulate several key properties of synaptic transmitter release.
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Affiliation(s)
- Orit Zamir
- Physiology Department, University of Toronto, 1 King's College Circle, Room 3308, Toronto, Ontario, Canada M5S1A8
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45
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Hara Y, Katow H. Exclusive expression of hedgehog in small micromere descendants during early embryogenesis in the sea urchin, Hemicentrotus pulcherrimus. Gene Expr Patterns 2005; 5:503-10. [PMID: 15749078 DOI: 10.1016/j.modgep.2004.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2004] [Revised: 11/26/2004] [Accepted: 12/13/2004] [Indexed: 11/17/2022]
Abstract
Hedgehog (hh) is a multifunctional extracellular protein, and known as an essential signal molecule in morphogenetic movement in animal embryos. We have cloned, sequenced, and studied dynamic localization of Hphh, a hedgehog homologue of the sea urchin, Hemicentrotus pulcherrimus. The origin of Hphh transcribing cells was also verified during early embryogenesis. The amino acid sequence of Hphh shows high homology to Lvhh, an hh homologue cloned in the sea urchin, Lytechinus variegatus. Reverse transcriptase polymerase chain reaction showed that the transcription of Hphh occurred at and after 19 h post-fertilization (19 hpf) mesenchyme blastula stage until, at least, 69 hpf 4-arm pluteus stage. Whole mount in situ hybridization showed Hphh transcription sites in a few cells at the tip of archenteron in 30 hpf gastrulae. At around 45 hpf 2-arm pluteus stage, the number of Hphh transcribed cells was 8, and unequally split to two groups, 5 cells in left coelomic sac and 3 cells in right coelomic sac. A cell lineage tracing by staining the small micromeres with 5-Bromo-2-deoxyuridine showed that Hphh was transcribed exclusively in all the small micromere descendants and comprised the coelomic sacs in 69 hpf plutei.
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Affiliation(s)
- Yoshinobu Hara
- Laboratory of Developmental and Cell Biology, Graduate School of Life Sciences, Tohoku University, Asamushi, Aomori 039-3501, Japan
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46
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Beasley CL, Honer WG, Bergmann K, Falkai P, Lütjohann D, Bayer TA. Reductions in cholesterol and synaptic markers in association cortex in mood disorders. Bipolar Disord 2005; 7:449-55. [PMID: 16176438 DOI: 10.1111/j.1399-5618.2005.00239.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Cholesterol forms an integral part of cell membranes and is a major component of myelin. Furthermore, cholesterol also plays a vital role in the development, function and stability of synapses. While low serum cholesterol has previously been associated with mood disorders, cholesterol levels have yet to be quantified within the brain in these disorders. The aim of this study was to quantify sterol levels in the brains of patients with major psychiatric disorders and further to relate these levels to markers of myelin and synapses. METHODS Samples of visual association cortex were obtained postmortem from subjects with bipolar disorder (BPD), major depressive disorder (MDD) and schizophrenia (SCZ) and from controls (all n = 15). Concentrations of brain cholesterol, its precursors lathosterol, desmosterol and lanosterol and its metabolite 24S-hydroxycholesterol were determined by gas-liquid chromatography. Immunoreactivity for myelin basic protein (MBP), synaptophysin and VAMP was quantified by enzyme-linked immunosorbent assay. RESULTS Cholesterol levels were 13% lower in MDD (p = 0.018) and 10% lower in BPD (p = 0.052) compared with controls. Cholesterol precursor or metabolite concentrations did not differ between groups. Synaptophysin immunoreactivity was 20% lower in BPD (p = 0.025) and VAMP immunoreactivity 37% lower in MDD (p = 0.032) and 45% lower in BPD (p = 0.009). MBP immunoreactivity was not altered in any disorder. CONCLUSIONS Our data suggest that lower brain cholesterol levels and a reduction in synapses may be features of mood disorders.
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Affiliation(s)
- Clare L Beasley
- Center for Complex Disorders, Department of Psychiatry, University of British Columbia, Vancouver, Canada.
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47
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Assanasen C, Mineo C, Seetharam D, Yuhanna IS, Marcel YL, Connelly MA, Williams DL, de la Llera-Moya M, Shaul PW, Silver DL. Cholesterol binding, efflux, and a PDZ-interacting domain of scavenger receptor-BI mediate HDL-initiated signaling. J Clin Invest 2005. [PMID: 15841181 DOI: 10.1172/jci23858, 10.1172/jci200523858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The binding of HDL to scavenger receptor-BI (SR-BI) mediates cholesterol movement. HDL also induces multiple cellular signals, which in endothelium occur through SR-BI and converge to activate eNOS. To determine the molecular basis of a signaling event induced by HDL, we examined the proximal mechanisms in HDL activation of eNOS. In endothelial cells, HDL and methyl-beta-cyclodextrin caused comparable eNOS activation, whereas cholesterol-loaded methyl-beta-cyclodextrin had no effect. Phosphatidylcholine-loaded HDL caused greater stimulation than native HDL, and blocking antibody against SR-BI, which prevents cholesterol efflux, prevented eNOS activation. In a reconstitution model in COS-M6 cells, wild-type SR-BI mediated eNOS activation by both HDL and small unilamellar vesicles (SUVs), whereas the SR-BI mutant AVI, which is incapable of efflux to SUV, transmitted signal by only HDL. In addition, eNOS activation by methyl-beta-cyclodextrin was SR-BI dependent. Studies of mutant and chimeric class B scavenger receptors revealed that the C-terminal cytoplasmic PDZ-interacting domain and the C-terminal transmembrane domains of SR-BI are both necessary for HDL signaling. Furthermore, we demonstrated direct binding of cholesterol to the C-terminal transmembrane domain using a photoactivated derivative of cholesterol. Thus, HDL signaling requires cholesterol binding and efflux and C-terminal domains of SR-BI, and SR-BI serves as a cholesterol sensor on the plasma membrane.
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Affiliation(s)
- Chatchawin Assanasen
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Assanasen C, Mineo C, Seetharam D, Yuhanna IS, Marcel YL, Connelly MA, Williams DL, de la Llera-Moya M, Shaul PW, Silver DL. Cholesterol binding, efflux, and a PDZ-interacting domain of scavenger receptor-BI mediate HDL-initiated signaling. J Clin Invest 2005; 115:969-77. [PMID: 15841181 PMCID: PMC1069105 DOI: 10.1172/jci23858] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 02/02/2005] [Indexed: 12/23/2022] Open
Abstract
The binding of HDL to scavenger receptor-BI (SR-BI) mediates cholesterol movement. HDL also induces multiple cellular signals, which in endothelium occur through SR-BI and converge to activate eNOS. To determine the molecular basis of a signaling event induced by HDL, we examined the proximal mechanisms in HDL activation of eNOS. In endothelial cells, HDL and methyl-beta-cyclodextrin caused comparable eNOS activation, whereas cholesterol-loaded methyl-beta-cyclodextrin had no effect. Phosphatidylcholine-loaded HDL caused greater stimulation than native HDL, and blocking antibody against SR-BI, which prevents cholesterol efflux, prevented eNOS activation. In a reconstitution model in COS-M6 cells, wild-type SR-BI mediated eNOS activation by both HDL and small unilamellar vesicles (SUVs), whereas the SR-BI mutant AVI, which is incapable of efflux to SUV, transmitted signal by only HDL. In addition, eNOS activation by methyl-beta-cyclodextrin was SR-BI dependent. Studies of mutant and chimeric class B scavenger receptors revealed that the C-terminal cytoplasmic PDZ-interacting domain and the C-terminal transmembrane domains of SR-BI are both necessary for HDL signaling. Furthermore, we demonstrated direct binding of cholesterol to the C-terminal transmembrane domain using a photoactivated derivative of cholesterol. Thus, HDL signaling requires cholesterol binding and efflux and C-terminal domains of SR-BI, and SR-BI serves as a cholesterol sensor on the plasma membrane.
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Affiliation(s)
- Chatchawin Assanasen
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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49
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Assanasen C, Mineo C, Seetharam D, Yuhanna IS, Marcel YL, Connelly MA, Williams DL, de la Llera-Moya M, Shaul PW, Silver DL. Cholesterol binding, efflux, and a PDZ-interacting domain of scavenger receptor-BI mediate HDL-initiated signaling. J Clin Invest 2005. [PMID: 15841181 DOI: 10.1172/jci200523858] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The binding of HDL to scavenger receptor-BI (SR-BI) mediates cholesterol movement. HDL also induces multiple cellular signals, which in endothelium occur through SR-BI and converge to activate eNOS. To determine the molecular basis of a signaling event induced by HDL, we examined the proximal mechanisms in HDL activation of eNOS. In endothelial cells, HDL and methyl-beta-cyclodextrin caused comparable eNOS activation, whereas cholesterol-loaded methyl-beta-cyclodextrin had no effect. Phosphatidylcholine-loaded HDL caused greater stimulation than native HDL, and blocking antibody against SR-BI, which prevents cholesterol efflux, prevented eNOS activation. In a reconstitution model in COS-M6 cells, wild-type SR-BI mediated eNOS activation by both HDL and small unilamellar vesicles (SUVs), whereas the SR-BI mutant AVI, which is incapable of efflux to SUV, transmitted signal by only HDL. In addition, eNOS activation by methyl-beta-cyclodextrin was SR-BI dependent. Studies of mutant and chimeric class B scavenger receptors revealed that the C-terminal cytoplasmic PDZ-interacting domain and the C-terminal transmembrane domains of SR-BI are both necessary for HDL signaling. Furthermore, we demonstrated direct binding of cholesterol to the C-terminal transmembrane domain using a photoactivated derivative of cholesterol. Thus, HDL signaling requires cholesterol binding and efflux and C-terminal domains of SR-BI, and SR-BI serves as a cholesterol sensor on the plasma membrane.
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Affiliation(s)
- Chatchawin Assanasen
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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50
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Abstract
Secreted signaling proteins function in a diverse array of essential patterning events during metazoan development, ranging from embryonic segmentation in insects to neural tube differentiation in vertebrates. These proteins generally are expressed in a localized manner, and they may elicit distinct concentration-dependent responses in the cells of surrounding tissues and structures, thus functioning as morphogens that specify the pattern of cellular responses by their tissue distribution. Given the importance of signal distribution, it is notable that the Hedgehog (Hh) and Wnt proteins, two of the most important families of such signals, are known to be covalently modified by lipid moieties, the membrane-anchoring properties of which are not consistent with passive models of protein mobilization within tissues. This review focuses on the mechanisms underlying biogenesis of the mature Hh proteins, which are dually modified by cholesteryl and palmitoyl adducts, as well as on the relationship between Hh proteins and the self-splicing proteins (i.e., proteins containing inteins) and the Hh-like proteins of nematodes. We further discuss the cellular mechanisms that have evolved to handle lipidated Hh proteins in the spatial deployment of the signal in developing tissues and the more recent findings that implicate palmitate modification as an important feature of Wnt signaling proteins.
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Affiliation(s)
- Randall K Mann
- Department of Molecular Biology and Genetics and Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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