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Rodríguez-Martín M, Báez-Flores J, Ribes V, Isidoro-García M, Lacal J, Prieto-Matos P. Non-Mammalian Models for Understanding Neurological Defects in RASopathies. Biomedicines 2024; 12:841. [PMID: 38672195 PMCID: PMC11048513 DOI: 10.3390/biomedicines12040841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/27/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
RASopathies, a group of neurodevelopmental congenital disorders stemming from mutations in the RAS/MAPK pathway, present a unique opportunity to delve into the intricacies of complex neurological disorders. Afflicting approximately one in a thousand newborns, RASopathies manifest as abnormalities across multiple organ systems, with a pronounced impact on the central and peripheral nervous system. In the pursuit of understanding RASopathies' neurobiology and establishing phenotype-genotype relationships, in vivo non-mammalian models have emerged as indispensable tools. Species such as Danio rerio, Drosophila melanogaster, Caenorhabditis elegans, Xenopus species and Gallus gallus embryos have proven to be invaluable in shedding light on the intricate pathways implicated in RASopathies. Despite some inherent weaknesses, these genetic models offer distinct advantages over traditional rodent models, providing a holistic perspective on complex genetics, multi-organ involvement, and the interplay among various pathway components, offering insights into the pathophysiological aspects of mutations-driven symptoms. This review underscores the value of investigating the genetic basis of RASopathies for unraveling the underlying mechanisms contributing to broader neurological complexities. It also emphasizes the pivotal role of non-mammalian models in serving as a crucial preliminary step for the development of innovative therapeutic strategies.
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Affiliation(s)
- Mario Rodríguez-Martín
- Laboratory of Functional Genetics of Rare Diseases, Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca, Spain; (M.R.-M.); (J.B.-F.)
- Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain; (M.I.-G.); (P.P.-M.)
| | - Juan Báez-Flores
- Laboratory of Functional Genetics of Rare Diseases, Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca, Spain; (M.R.-M.); (J.B.-F.)
- Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain; (M.I.-G.); (P.P.-M.)
| | - Vanessa Ribes
- Institut Jacques Monod, Université Paris Cité, CNRS, F-75013 Paris, France;
| | - María Isidoro-García
- Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain; (M.I.-G.); (P.P.-M.)
- Clinical Biochemistry Department, Hospital Universitario de Salamanca, 37007 Salamanca, Spain
- Clinical Rare Diseases Reference Unit DiERCyL, 37007 Castilla y León, Spain
- Department of Medicine, University of Salamanca, 37007 Salamanca, Spain
| | - Jesus Lacal
- Laboratory of Functional Genetics of Rare Diseases, Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca, Spain; (M.R.-M.); (J.B.-F.)
- Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain; (M.I.-G.); (P.P.-M.)
| | - Pablo Prieto-Matos
- Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain; (M.I.-G.); (P.P.-M.)
- Clinical Rare Diseases Reference Unit DiERCyL, 37007 Castilla y León, Spain
- Department of Pediatrics, Hospital Universitario de Salamanca, 37007 Salamanca, Spain
- Department of Biomedical and Diagnostics Science, University of Salamanca, 37007 Salamanca, Spain
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Holst JD, Murphy LG, Gorman MJ, Ragan EJ. Comparison of insect and human cytochrome b561 proteins: Insights into candidate ferric reductases in insects. PLoS One 2023; 18:e0291564. [PMID: 38039324 PMCID: PMC10691727 DOI: 10.1371/journal.pone.0291564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 11/19/2023] [Indexed: 12/03/2023] Open
Abstract
Cytochrome b561 (cytb561) proteins comprise a family of transmembrane oxidoreductases that transfer single electrons across a membrane. Most eukaryotic species, including insects, possess multiple cytb561 homologs. To learn more about this protein family in insects, we carried out a bioinformatics-based investigation of cytb561 family members from nine species representing eight insect orders. We performed a phylogenetic analysis to classify insect cytb561 ortholog groups. We then conducted sequence analyses and analyzed protein models to predict structural elements that may impact the biological functions and localization of these proteins, with a focus on possible ferric reductase activity. Our study revealed three ortholog groups, designated CG1275, Nemy, and CG8399, and a fourth group of less-conserved genes. We found that CG1275 and Nemy proteins are similar to a human ferric reductase, duodenal cytochrome b561 (Dcytb), and have many conserved amino acid residues that function in substrate binding in Dcytb. Notably, CG1275 and Nemy proteins contain a conserved histidine and other residues that play a role in ferric ion reduction by Dcytb. Nemy proteins were distinguished by a novel cysteine-rich cytoplasmic loop sequence. CG8399 orthologs are similar to a putative ferric reductase in humans, stromal cell-derived receptor 2. Like other members of the CYBDOM class of cytb561 proteins, these proteins contain reeler, DOMON, and cytb561 domains. Drosophila melanogaster CG8399 is the only insect cytb561 with known ferric reductase activity. Our investigation of the DOMON domain in CG8399 proteins revealed a probable heme-binding site and a possible site for ferric reduction. The fourth group includes a subgroup of proteins with a conserved "KXXXXKXH" non-cytoplasmic loop motif that may be a substrate binding site and is present in a potential ferric reductase, human tumor suppressor cytochrome b561. This study provides a foundation for future investigations of the biological functions of cytb561 genes in insects.
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Affiliation(s)
- Jessica D. Holst
- Department of Chemistry and Biochemistry, Metropolitan State University of Denver, Denver, Colorado, United States of America
| | - Laura G. Murphy
- Department of Chemistry and Biochemistry, Metropolitan State University of Denver, Denver, Colorado, United States of America
| | - Maureen J. Gorman
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas, United States of America
| | - Emily J. Ragan
- Department of Chemistry and Biochemistry, Metropolitan State University of Denver, Denver, Colorado, United States of America
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Ilina Y, Kaufmann P, Melander O, Press M, Thuene K, Bergmann A. Immunoassay-based quantification of full-length peptidylglycine alpha-amidating monooxygenase in human plasma. Sci Rep 2023; 13:10827. [PMID: 37402878 DOI: 10.1038/s41598-023-37976-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 06/30/2023] [Indexed: 07/06/2023] Open
Abstract
A one-step sandwich chemiluminescence immunometric assay (LIA) was developed for the quantification of bifunctional peptidylglycine-α-amidating monooxygenase (PAM) in human plasma (PAM-LIA). PAM is responsible for the activation of more than half of known peptide hormones through C-terminal α-amidation. The assay employed antibodies targeting specific catalytic PAM-subunits, peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL), to ensure detection of full-length PAM. The PAM-LIA assay was calibrated with a human recombinant PAM enzyme and achieved a detection limit of 189 pg/mL and a quantification limit of 250 pg/mL. The assay demonstrated good inter-assay (6.7%) and intra-assay (2.2%) variabilities. It exhibited linearity when accessed by gradual dilution or random mixing of plasma samples. The accuracy of the PAM-LIA was determined to be 94.7% through spiking recovery experiments, and the signal recovery after substance interference was 94-96%. The analyte showed 96% stability after six freeze-thaw cycles. The assay showed strong correlation with matched EDTA and serum samples, as well as matched EDTA and Li-Heparin samples. Additionally, a high correlation was observed between α-amidating activity and PAM-LIA. Finally, the PAM-LIA assay was successfully applied to a sub-cohort of a Swedish population-based study, comprising 4850 individuals, confirming its suitability for routine high throughput screening.
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Affiliation(s)
- Yulia Ilina
- PAM Theragnostics GmbH, Neuendorfstr. 15A, 16761, Hennigsdorf, Germany.
| | - Paul Kaufmann
- PAM Theragnostics GmbH, Neuendorfstr. 15A, 16761, Hennigsdorf, Germany
| | - Olle Melander
- Department of Clinical Sciences Malmö, Lund University, 205 02, Malmö, Sweden
- Department of Emergency and Internal Medicine, Skåne University Hospital, Malmö, Sweden
| | - Michaela Press
- PAM Theragnostics GmbH, Neuendorfstr. 15A, 16761, Hennigsdorf, Germany
| | - Katrin Thuene
- PAM Theragnostics GmbH, Neuendorfstr. 15A, 16761, Hennigsdorf, Germany
| | - Andreas Bergmann
- PAM Theragnostics GmbH, Neuendorfstr. 15A, 16761, Hennigsdorf, Germany
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Abstract
Iron is an essential micronutrient for all types of organisms; however, iron has chemical properties that can be harmful to cells. Because iron is both necessary and potentially damaging, insects have homeostatic processes that control the redox state, quantity, and location of iron in the body. These processes include uptake of iron from the diet, intracellular and extracellular iron transport, and iron storage. Early studies of iron-binding proteins in insects suggested that insects and mammals have surprisingly different mechanisms of iron homeostasis, including different primary mechanisms for exporting iron from cells and for transporting iron from one cell to another, and subsequent studies have continued to support this view. This review summarizes current knowledge about iron homeostasis in insects, compares insect and mammalian iron homeostasis mechanisms, and calls attention to key remaining knowledge gaps.
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Affiliation(s)
- Maureen J Gorman
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA;
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Espina JEC, Bagamasbad PD. Synergistic gene regulation by thyroid hormone and glucocorticoid in the hippocampus. VITAMINS AND HORMONES 2021; 118:35-81. [PMID: 35180933 DOI: 10.1016/bs.vh.2021.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The hippocampus is considered the center for learning and memory in the brain, and its development and function is greatly affected by the thyroid and stress axes. Thyroid hormone (TH) and glucocorticoids (GC) are known to have a synergistic effect on developmental programs across several vertebrate species, and their effects on hippocampal structure and function are well-documented. However, there are few studies that focus on the processes and genes that are cooperatively regulated by the two hormone axes. Cross-regulation of the thyroid and stress axes in the hippocampus occurs on multiple levels such that TH can regulate the expression of the GC receptor (GR) while GC can modulate tissue sensitivity to TH by controlling the expression of TH receptor (TR) and enzymes involved in TH biosynthesis. Thyroid hormone and GC are also known to synergistically regulate the transcription of genes associated with neuronal function and development. Synergistic gene regulation by TH and GC may occur through the direct, cooperative action of TR and GR on common target genes, or by indirect mechanisms involving gene regulatory cascades activated by TR and GR. In this chapter, we describe the known physiological effects and underlying molecular mechanisms of TH and GC synergistic gene regulation in the hippocampus.
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Affiliation(s)
- Jose Ezekiel C Espina
- National Institute of Molecular Biology and Biotechnology, University of the Philippines Diliman, Quezon City, Philippines
| | - Pia D Bagamasbad
- National Institute of Molecular Biology and Biotechnology, University of the Philippines Diliman, Quezon City, Philippines.
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Rindi G, Wiedenmann B. Neuroendocrine neoplasia of the gastrointestinal tract revisited: towards precision medicine. Nat Rev Endocrinol 2020; 16:590-607. [PMID: 32839579 DOI: 10.1038/s41574-020-0391-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/03/2020] [Indexed: 02/06/2023]
Abstract
Over the past 5 years, a number of notable research advances have been made in the field of neuroendocrine cancer, specifically with regard to neuroendocrine cancer of the gastrointestinal tract. The aim of this Review is to provide an update on current knowledge that has proven effective for the clinical management of patients with these tumours. For example, for the first time in the tubular gastrointestinal tract, well-differentiated high-grade (grade 3) tumours and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are defined in the WHO classification. This novel classification enables efficient identification of the most aggressive well-differentiated neuroendocrine tumours and helps in defining the degree of aggressiveness of MiNENs. The Review also discusses updates to epidemiology, cell biology (including vesicle-specific components) and the as-yet-unresolved complex genetic background that varies according to site and differentiation status. The Review summarizes novel diagnostic instruments, including molecules associated with the secretory machinery, novel radiological approaches (including pattern recognition techniques), novel PET tracers and liquid biopsy combined with DNA or RNA assays. Surgery remains the treatment mainstay; however, peptide receptor radionuclide therapy with novel radioligands and new emerging medical therapies (including vaccination and immunotherapy) are evolving and being tested in clinical trials, which are summarized and critically reviewed here.
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Affiliation(s)
- Guido Rindi
- Università Cattolica del Sacro Cuore, Rome, Italy.
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.
| | - Bertram Wiedenmann
- Charité, Campus Virchow Klinikum and Charité Mitte, University Medicine Berlin, Berlin, Germany
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Carbon Monoxide, a Retrograde Messenger Generated in Postsynaptic Mushroom Body Neurons, Evokes Noncanonical Dopamine Release. J Neurosci 2020; 40:3533-3548. [PMID: 32253360 DOI: 10.1523/jneurosci.2378-19.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 02/12/2020] [Accepted: 03/19/2020] [Indexed: 02/06/2023] Open
Abstract
Dopaminergic neurons innervate extensive areas of the brain and release dopamine (DA) onto a wide range of target neurons. However, DA release is also precisely regulated. In Drosophila melanogaster brain explant preparations, DA is released specifically onto α3/α'3 compartments of mushroom body (MB) neurons that have been coincidentally activated by cholinergic and glutamatergic inputs. The mechanism for this precise release has been unclear. Here we found that coincidentally activated MB neurons generate carbon monoxide (CO), which functions as a retrograde signal evoking local DA release from presynaptic terminals. CO production depends on activity of heme oxygenase in postsynaptic MB neurons, and CO-evoked DA release requires Ca2+ efflux through ryanodine receptors in DA terminals. CO is only produced in MB areas receiving coincident activation, and removal of CO using scavengers blocks DA release. We propose that DA neurons use two distinct modes of transmission to produce global and local DA signaling.SIGNIFICANCE STATEMENT Dopamine (DA) is needed for various higher brain functions, including memory formation. However, DA neurons form extensive synaptic connections, while memory formation requires highly specific and localized DA release. Here we identify a mechanism through which DA release from presynaptic terminals is controlled by postsynaptic activity. Postsynaptic neurons activated by cholinergic and glutamatergic inputs generate carbon monoxide, which acts as a retrograde messenger inducing presynaptic DA release. Released DA is required for memory-associated plasticity. Our work identifies a novel mechanism that restricts DA release to the specific postsynaptic sites that require DA during memory formation.
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Coordinated transcriptional regulation by thyroid hormone and glucocorticoid interaction in adult mouse hippocampus-derived neuronal cells. PLoS One 2019; 14:e0220378. [PMID: 31348800 PMCID: PMC6660079 DOI: 10.1371/journal.pone.0220378] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/15/2019] [Indexed: 12/04/2022] Open
Abstract
The hippocampus is a well-known target of thyroid hormone (TH; e.g., 3,5,3’-triiodothyronine—T3) and glucocorticoid (GC; e.g., corticosterone—CORT) action. Despite evidence that TH and GC play critical roles in neural development and function, few studies have identified genes and patterns of gene regulation influenced by the interaction of these hormones at a genome-wide scale. In this study we investigated gene regulation by T3, CORT, and T3 + CORT in the mouse hippocampus-derived cell line HT-22. We treated cells with T3, CORT, or T3 + CORT for 4 hr before cell harvest and RNA isolation for microarray analysis. We identified 9 genes regulated by T3, 432 genes by CORT, and 412 genes by T3 + CORT. Among the 432 CORT-regulated genes, there were 203 genes that exhibited an altered CORT response in the presence of T3, suggesting that T3 plays a significant role in modulating CORT-regulated genes. We also found 80 genes synergistically induced, and 73 genes synergistically repressed by T3 + CORT treatment. We performed in silico analysis using publicly available mouse neuronal chromatin immunoprecipitation-sequencing datasets and identified a considerable number of synergistically regulated genes with TH receptor and GC receptor peaks mapping within 1 kb of chromatin marks indicative of hormone-responsive enhancer regions. Functional annotation clustering of synergistically regulated genes reveal the relevance of proteasomal-dependent degradation, neuroprotective effect of growth hormones, and neuroinflammatory responses as key pathways to how TH and GC may coordinately influence learning and memory. Taken together, our transcriptome data represents a promising exploratory dataset for further study of common molecular mechanisms behind synergistic TH and GC gene regulation, and identify specific genes and their role in processes mediated by cross-talk between the thyroid and stress axes in a mammalian hippocampal model system.
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9
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Affiliation(s)
- Kazuo Kobayashi
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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10
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Rolandi C, Lighton JRB, de la Vega GJ, Schilman PE, Mensch J. Genetic variation for tolerance to high temperatures in a population of Drosophila melanogaster. Ecol Evol 2018; 8:10374-10383. [PMID: 30464811 PMCID: PMC6238130 DOI: 10.1002/ece3.4409] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 07/01/2018] [Accepted: 07/02/2018] [Indexed: 12/26/2022] Open
Abstract
The range of thermal tolerance is one of the main factors influencing the geographic distribution of species. Climate change projections predict increases in average and extreme temperatures over the coming decades; hence, the ability of living beings to resist these changes will depend on physiological and adaptive responses. On an evolutionary scale, changes will occur as the result of selective pressures on individual heritable differences. In this work, we studied the genetic basis of tolerance to high temperatures in the fly Drosophila melanogaster and whether this species presents sufficient genetic variability to allow expansion of its upper thermo-tolerance limit. To do so, we used adult flies derived from a natural population belonging to the Drosophila Genetic Reference Panel, for which genomic sequencing data are available. We characterized the phenotypic variation of the upper thermal limit in 34 lines by measuring knockdown temperature (i.e., critical thermal maximum [CTmax]) by exposing flies to a ramp of increasing temperature (0.25°C/min). Fourteen percent of the variation in CTmax is explained by the genetic variation across lines, without a significant sexual dimorphism. Through a genomewide association study, 12 single nucleotide polymorphisms associated with the CTmax were identified. In most of these SNPs, the less frequent allele increased the upper thermal limit suggesting that this population harbors raw genetic variation capable of expanding its heat tolerance. This potential upper thermal tolerance increase has implications under the global warming scenario. Past climatic records show a very low incidence of days above CTmax (10 days over 25 years); however, future climate scenarios predict 243 days with extreme high temperature above CTmax from 2045 to 2070. Thus, in the context of the future climate warming, rising temperatures might drive the evolution of heat tolerance in this population by increasing the frequency of the alleles associated with higher CTmax.
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Affiliation(s)
- Carmen Rolandi
- IBBEA‐CONICET‐UBA. DBBEAFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
| | | | - Gerardo J. de la Vega
- Grupo de Ecología de Poblaciones de Insectos (GEPI)INTA EEA BarilocheBarilocheArgentina
| | - Pablo E. Schilman
- IBBEA‐CONICET‐UBA. DBBEAFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
| | - Julián Mensch
- IEGEBA‐CONICET‐UBADEGEFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
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11
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Kumar D, Mains RE, Eipper BA. 60 YEARS OF POMC: From POMC and α-MSH to PAM, molecular oxygen, copper, and vitamin C. J Mol Endocrinol 2016; 56:T63-76. [PMID: 26667899 PMCID: PMC4899100 DOI: 10.1530/jme-15-0266] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 12/14/2015] [Indexed: 12/19/2022]
Abstract
A critical role for peptide C-terminal amidation was apparent when the first bioactive peptides were identified. The conversion of POMC into adrenocorticotropic hormone and then into α-melanocyte-stimulating hormone, an amidated peptide, provided a model system for identifying the amidating enzyme. Peptidylglycine α-amidating monooxygenase (PAM), the only enzyme that catalyzes this modification, is essential; mice lacking PAM survive only until mid-gestation. Purification and cloning led to the discovery that the amidation of peptidylglycine substrates proceeds in two steps: peptidylglycine α-hydroxylating monooxygenase catalyzes the copper- and ascorbate-dependent α-hydroxylation of the peptidylglycine substrate; peptidyl-α-hydroxyglycine α-amidating lyase cleaves the N-C bond, producing amidated product and glyoxylate. Both enzymes are contained in the luminal domain of PAM, a type 1 integral membrane protein. The structures of both catalytic cores have been determined, revealing how they interact with metals, molecular oxygen, and substrate to catalyze both reactions. Although not essential for activity, the intrinsically disordered cytosolic domain is essential for PAM trafficking. A phylogenetic survey led to the identification of bifunctional membrane PAM in Chlamydomonas, a unicellular eukaryote. Accumulating evidence points to a role for PAM in copper homeostasis and in retrograde signaling from the lumen of the secretory pathway to the nucleus. The discovery of PAM in cilia, cellular antennae that sense and respond to environmental stimuli, suggests that much remains to be learned about this ancient protein.
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Affiliation(s)
- Dhivya Kumar
- Departments of Molecular Biology and BiophysicsUniversity of Connecticut Health Center, Farmington, Connecticut, USA
| | - Richard E Mains
- Department of NeuroscienceUniversity of Connecticut Health Center, Farmington, Connecticut, USA
| | - Betty A Eipper
- Departments of Molecular Biology and BiophysicsUniversity of Connecticut Health Center, Farmington, Connecticut, USA Department of NeuroscienceUniversity of Connecticut Health Center, Farmington, Connecticut, USA
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Knight D, Iliadi KG, Iliadi N, Wilk R, Hu J, Krause HM, Taylor P, Moran MF, Boulianne GL. Distinct Regulation of Transmitter Release at the Drosophila NMJ by Different Isoforms of nemy. PLoS One 2015; 10:e0132548. [PMID: 26237434 PMCID: PMC4523183 DOI: 10.1371/journal.pone.0132548] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/17/2015] [Indexed: 11/18/2022] Open
Abstract
Synaptic transmission is highly plastic and subject to regulation by a wide variety of neuromodulators and neuropeptides. In the present study, we have examined the role of isoforms of the cytochrome b561 homologue called no extended memory (nemy) in regulation of synaptic strength and plasticity at the neuromuscular junction (NMJ) of third instar larvae in Drosophila. Specifically, we generated two independent excisions of nemy that differentially affect the expression of nemy isoforms. We show that the nemy45 excision, which specifically reduces the expression of the longest splice form of nemy, leads to an increase in stimulus evoked transmitter release and altered synaptic plasticity at the NMJ. Conversely, the nemy26.2 excision, which appears to reduce the expression of all splice forms except the longest splice isoform, shows a reduction in stimulus evoked transmitter release, and enhanced synaptic plasticity. We further show that nemy45 mutants have reduced levels of amidated peptides similar to that observed in peptidyl-glycine hydryoxylating mono-oxygenase (PHM) mutants. In contrast, nemy26.2 mutants show no defects in peptide amidation but rather display a decrease in Tyramine β hydroxylase activity (TβH). Taken together, these results show non-redundant roles for the different nemy isoforms and shed light on the complex regulation of neuromodulators.
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Affiliation(s)
- David Knight
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
| | - Konstantin G. Iliadi
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
| | - Natalia Iliadi
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
| | - Ronit Wilk
- Department of Molecular Genetics, The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Jack Hu
- Department of Molecular Genetics, The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Henry M. Krause
- Department of Molecular Genetics, The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Paul Taylor
- Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, M5G 1L7, Canada
| | - Michael F. Moran
- Dept of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
- Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, M5G 1L7, Canada
| | - Gabrielle L. Boulianne
- Program in Developmental and Stem Cell Biology, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, M5G 0A4, Canada
- Dept of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
- * E-mail:
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Hadžić T, Park D, Abruzzi KC, Yang L, Trigg JS, Rohs R, Rosbash M, Taghert PH. Genome-wide features of neuroendocrine regulation in Drosophila by the basic helix-loop-helix transcription factor DIMMED. Nucleic Acids Res 2015; 43:2199-215. [PMID: 25634895 PMCID: PMC4344488 DOI: 10.1093/nar/gku1377] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Neuroendocrine (NE) cells use large dense core vesicles (LDCVs) to traffic, process, store and secrete neuropeptide hormones through the regulated secretory pathway. The dimmed (DIMM) basic helix-loop-helix transcription factor of Drosophila controls the level of regulated secretory activity in NE cells. To pursue its mechanisms, we have performed two independent genome-wide analyses of DIMM's activities: (i) in vivo chromatin immunoprecipitation (ChIP) to define genomic sites of DIMM occupancy and (ii) deep sequencing of purified DIMM neurons to characterize their transcriptional profile. By this combined approach, we showed that DIMM binds to conserved E-boxes in enhancers of 212 genes whose expression is enriched in DIMM-expressing NE cells. DIMM binds preferentially to certain E-boxes within first introns of specific gene isoforms. Statistical machine learning revealed that flanking regions of putative DIMM binding sites contribute to its DNA binding specificity. DIMM's transcriptional repertoire features at least 20 LDCV constituents. In addition, DIMM notably targets the pro-secretory transcription factor, creb-A, but significantly, DIMM does not target any neuropeptide genes. DIMM therefore prescribes the scale of secretory activity in NE neurons, by a systematic control of both proximal and distal points in the regulated secretory pathway.
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Affiliation(s)
- Tarik Hadžić
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Dongkook Park
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Katharine C Abruzzi
- Howard Hughes Medical Institute, National Center for Behavioral Genomics, Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Lin Yang
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Jennifer S Trigg
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Remo Rohs
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Michael Rosbash
- Howard Hughes Medical Institute, National Center for Behavioral Genomics, Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Paul H Taghert
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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Picco C, Scholz-Starke J, Naso A, Preger V, Sparla F, Trost P, Carpaneto A. How are cytochrome b561 electron currents controlled by membrane voltage and substrate availability? Antioxid Redox Signal 2014; 21:384-91. [PMID: 24410448 DOI: 10.1089/ars.2013.5809] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Direct recordings of electron currents mediated by cytochromes b561 (CYB561) are not available yet, despite the importance of these proteins in a variety of physiological functions, including neurotransmitter synthesis and dietary iron uptake. Here, we used the two-electrode voltage-clamp technique applied to Xenopus oocytes to demonstrate, for the first time, the generation of electron currents by a Drosophila member of the CYB561 superfamily named stromal cell-derived receptor 2 (SDR2). This experimental method, along with the theoretical development of a three-state kinetic model, supports the hypothesis that electron donor/acceptor concentrations and transmembrane voltage mutually control SDR2-mediated electron transport activity in a complex but predictable manner.
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15
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Drosophila melanogaster as a genetic model system to study neurotransmitter transporters. Neurochem Int 2014; 73:71-88. [PMID: 24704795 DOI: 10.1016/j.neuint.2014.03.015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/20/2014] [Accepted: 03/24/2014] [Indexed: 12/30/2022]
Abstract
The model genetic organism Drosophila melanogaster, commonly known as the fruit fly, uses many of the same neurotransmitters as mammals and very similar mechanisms of neurotransmitter storage, release and recycling. This system offers a variety of powerful molecular-genetic methods for the study of transporters, many of which would be difficult in mammalian models. We review here progress made using Drosophila to understand the function and regulation of neurotransmitter transporters and discuss future directions for its use.
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Asard H, Barbaro R, Trost P, Bérczi A. Cytochromes b561: ascorbate-mediated trans-membrane electron transport. Antioxid Redox Signal 2013; 19:1026-35. [PMID: 23249217 PMCID: PMC3763232 DOI: 10.1089/ars.2012.5065] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Cytochromes b561 (CYB561s) constitute a family of trans-membrane (TM), di-heme proteins, occurring in a variety of organs and cell types, in plants and animals, and using ascorbate (ASC) as an electron donor. CYB561s function as monodehydroascorbate reductase, regenerating ASC, and as Fe³⁺-reductases, providing reduced iron for TM transport. A CYB561-core domain is also associated with dopamine β-monooxygenase redox domains (DOMON) in ubiquitous CYBDOM proteins. In plants, CYBDOMs form large protein families. Physiological functions supported by CYB561s and CYBDOMs include stress defense, cell wall modifications, iron metabolism, tumor suppression, and various neurological processes, including memory retention. CYB561s, therefore, significantly broaden our view on the physiological roles of ASC. RECENT ADVANCES The ubiquitous nature of CYB561s is only recently being recognized. Significant advances have been made through the study of recombinant CYB561s, revealing structural and functional properties of a unique "two-heme four-helix" protein configuration. In addition, the DOMON domains of CYBDOMs are suggested to contain another heme b. CRITICAL ISSUES New CYB561 proteins are still being identified, and there is a need to provide an insight and overview on the various roles of these proteins and their structural properties. FUTURE DIRECTIONS Mutant studies will reveal in greater detail the mechanisms by which CYB561s and CYBDOMs participate in cell metabolism in plants and animals. Moreover, the availability of efficient heterologous expression systems should allow protein crystallization, more detailed (atomic-level) structural information, and insights into the intra-molecular mechanism of electron transport.
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Affiliation(s)
- Han Asard
- Department of Biology, University of Antwerp, Antwerp, Belgium.
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Ul-Hasan S, Burgess DM, Gajewiak J, Li Q, Hu H, Yandell M, Olivera BM, Bandyopadhyay PK. Characterization of the peptidylglycine α-amidating monooxygenase (PAM) from the venom ducts of neogastropods, Conus bullatus and Conus geographus. Toxicon 2013; 74:215-24. [PMID: 23994590 DOI: 10.1016/j.toxicon.2013.08.054] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/15/2013] [Accepted: 08/21/2013] [Indexed: 11/29/2022]
Abstract
Cone snails, genus Conus, are predatory marine snails that use venom to capture their prey. This venom contains a diverse array of peptide toxins, known as conotoxins, which undergo a diverse set of posttranslational modifications. Amidating enzymes modify peptides and proteins containing a C-terminal glycine residue, resulting in loss of the glycine residue and amidation of the preceding residue. A significant fraction of peptides present in the venom of cone snails contain C-terminal amidated residues, which are important for optimizing biological activity. This study describes the characterization of the amidating enzyme, peptidylglycine α-amidating monooxygenase (PAM), present in the venom duct of cone snails, Conus bullatus and Conus geographus. PAM is known to carry out two functions, peptidyl α-hydroxylating monooxygenase (PHM) and peptidylamido-glycolate lyase (PAL). In some animals, such as Drosophila melanogaster, these two functions are present in separate polypeptides, working as individual enzymes. In other animals, such as mammals and in Aplysia californica, PAM activity resides in a single, bifunctional polypeptide. Using specific oligonucleotide primers and reverse transcription-polymerase chain reaction we have identified and cloned from the venom duct cDNA library, a cDNA with 49% homology to PAM from A. californica. We have determined that both the PHM and PAL activities are encoded in one mRNA polynucleotide in both C. bullatus and C. geographus. We have directly demonstrated enzymatic activity catalyzing the conversion of dansyl-YVG-COOH to dansyl-YV-NH2 in cloned cDNA expressed in Drosophila S2 cells.
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Affiliation(s)
- Sabah Ul-Hasan
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA
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18
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Short neuropeptide F acts as a functional neuromodulator for olfactory memory in Kenyon cells of Drosophila mushroom bodies. J Neurosci 2013; 33:5340-5. [PMID: 23516298 DOI: 10.1523/jneurosci.2287-12.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In insects, many complex behaviors, including olfactory memory, are controlled by a paired brain structure, the so-called mushroom bodies (MB). In Drosophila, the development, neuroanatomy, and function of intrinsic neurons of the MB, the Kenyon cells, have been well characterized. Until now, several potential neurotransmitters or neuromodulators of Kenyon cells have been anatomically identified. However, whether these neuroactive substances of the Kenyon cells are functional has not been clarified yet. Here we show that a neuropeptide precursor gene encoding four types of short neuropeptide F (sNPF) is required in the Kenyon cells for appetitive olfactory memory. We found that activation of Kenyon cells by expressing a thermosensitive cation channel (dTrpA1) leads to a decrease in sNPF immunoreactivity in the MB lobes. Targeted expression of RNA interference against the sNPF precursor in Kenyon cells results in a highly significant knockdown of sNPF levels. This knockdown of sNPF in the Kenyon cells impairs sugar-rewarded olfactory memory. This impairment is not due to a defect in the reflexive sugar preference or odor response. Consistently, knockdown of sNPF receptors outside the MB causes deficits in appetitive memory. Altogether, these results suggest that sNPF is a functional neuromodulator released by Kenyon cells.
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Mandilaras K, Pathmanathan T, Missirlis F. Iron absorption in Drosophila melanogaster. Nutrients 2013; 5:1622-47. [PMID: 23686013 PMCID: PMC3708341 DOI: 10.3390/nu5051622] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 12/20/2022] Open
Abstract
The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.
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Affiliation(s)
- Konstantinos Mandilaras
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK; E-Mail:
| | - Tharse Pathmanathan
- Department of Physiology, Biophysics and Neuroscience, CINVESTAV-IPN, IPN Avenue 2508, Zacatenco, 07360, Mexico City, Mexico; E-Mail:
| | - Fanis Missirlis
- Department of Physiology, Biophysics and Neuroscience, CINVESTAV-IPN, IPN Avenue 2508, Zacatenco, 07360, Mexico City, Mexico; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +52-55-5747-3963; Fax: +52-55-5747-5713
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20
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Drosophila Memory Research through Four Eras. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-415823-8.00027-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Chintapalli VR, Terhzaz S, Wang J, Al Bratty M, Watson DG, Herzyk P, Davies SA, Dow JAT. Functional correlates of positional and gender-specific renal asymmetry in Drosophila. PLoS One 2012; 7:e32577. [PMID: 22496733 PMCID: PMC3319558 DOI: 10.1371/journal.pone.0032577] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Accepted: 01/27/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In humans and other animals, the internal organs are positioned asymmetrically in the body cavity, and disruption of this body plan can be fatal in humans. The mechanisms by which internal asymmetry are established are presently the subject of intense study; however, the functional significance of internal asymmetry (outside the brain) is largely unexplored. Is internal asymmetry functionally significant, or merely an expedient way of packing organs into a cavity? METHODOLOGY/PRINCIPAL FINDINGS Like humans, Drosophila shows internal asymmetry, with the gut thrown into stereotyped folds. There is also renal asymmetry, with the rightmost pair of renal (Malpighian) tubules always ramifying anteriorly, and the leftmost pair always sitting posteriorly in the body cavity. Accordingly, transcriptomes of anterior-directed (right-side) and posterior-directed (left-side) Malpighian (renal) tubules were compared in both adult male and female Drosophila. Although genes encoding the basic functions of the tubules (transport, signalling) were uniformly expressed, some functions (like innate immunity) showed positional or gender differences in emphasis; others, like calcium handling or the generation of potentially toxic ammonia, were reserved for just the right-side or left-side tubules, respectively. These findings correlated with the distinct locations of each tubule pair within the body cavity. Well known developmental genes (like dorsocross, dachshund and doublesex) showed continuing, patterned expression in adult tubules, implying that somatic tissues maintain both left-right and gender identities throughout life. Gender asymmetry was also noted, both in defence and in male-specific expression of receptors for neuropeptide F and sex-peptide: NPF elevated calcium only in male tubules. CONCLUSIONS/SIGNIFICANCE Accordingly, the physical asymmetry of the tubules in the body cavity is directly adaptive. Now that the detailed machinery underlying internal asymmetry is starting to be delineated, our work invites the investigation, not just of tissues in isolation, but in the context of their unique physical locations and milieux.
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Affiliation(s)
- Venkateswara R. Chintapalli
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Selim Terhzaz
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jing Wang
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Mohammed Al Bratty
- Strathclyde Institute for Pharmacy and Biomedical Sciences, Glasgow, United Kingdom
| | - David G. Watson
- Strathclyde Institute for Pharmacy and Biomedical Sciences, Glasgow, United Kingdom
| | - Pawel Herzyk
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Shireen A. Davies
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Julian A. T. Dow
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
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22
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Liu W, Wu G, Tsai AL, Kulmacz RJ. High-yield production, purification and characterization of functional human duodenal cytochrome b in an Escherichia coli system. Protein Expr Purif 2011; 79:115-21. [PMID: 21501687 DOI: 10.1016/j.pep.2011.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 03/29/2011] [Accepted: 04/01/2011] [Indexed: 11/15/2022]
Abstract
Human duodenal cytochrome b (Dcytb) is a transmembrane hemoprotein found in the duodenal brush border membrane and in erythrocytes. Dcytb has been linked to uptake of dietary iron and to ascorbate recycling in erythrocytes. Detailed biophysical and biochemical characterization of Dcytb has been limited by difficulties in expressing sufficient amounts of functional recombinant protein in yeast and insect cell systems. We have developed an Escherichia coli Rosetta-gami B(DE3) cell system for production of recombinant His-tagged human Dcytb with a yield of ∼26 mg of purified, ascorbate-reducible cytochrome per liter of culture. The recombinant protein is readily solubilized with n-dodecyl-β-D-maltoside and purified to electrophoretic homogeneity by one-step chromatography on cobalt affinity resin. The purified recombinant Dcytb has a heme to protein ratio very close to the theoretical value of 2 and retains functional reactivity with ascorbate, as assessed by spectroscopic and kinetic measurements. Ascorbate showed a marked kinetic selectivity for the high-potential heme center over the low-potential heme center in purified Dcytb. This new E. coli expression system for Dcytb offers ∼7-fold improvement in yield and other substantial advantages over existing expression systems for reliable production of functional Dcytb at levels suitable for biochemical, biophysical and structural characterization.
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Affiliation(s)
- Wen Liu
- Department of Internal Medicine, University of Texas Health Science Center, Houston, TX 77030, United States.
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23
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Kondylis V, Tang Y, Fuchs F, Boutros M, Rabouille C. Identification of ER proteins involved in the functional organisation of the early secretory pathway in Drosophila cells by a targeted RNAi screen. PLoS One 2011; 6:e17173. [PMID: 21383842 PMCID: PMC3044168 DOI: 10.1371/journal.pone.0017173] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 01/23/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In Drosophila, the early secretory apparatus comprises discrete paired Golgi stacks in close proximity to exit sites from the endoplasmic reticulum (tER sites), thus forming tER-Golgi units. Although many components involved in secretion have been identified, the structural components sustaining its organisation are less known. Here we set out to identify novel ER resident proteins involved in the of tER-Golgi unit organisation. RESULTS To do so, we designed a novel screening strategy combining a bioinformatics pre-selection with an RNAi screen. We first selected 156 proteins exhibiting known or related ER retention/retrieval signals from a list of proteins predicted to have a signal sequence. We then performed a microscopy-based primary and confirmation RNAi screen in Drosophila S2 cells directly scoring the organisation of the tER-Golgi units. We identified 49 hits, most of which leading to an increased number of smaller tER-Golgi units (MG for "more and smaller Golgi") upon depletion. 16 of them were validated and characterised, showing that this phenotype was not due to an inhibition in secretion, a block in G2, or ER stress. Interestingly, the MG phenotype was often accompanied by an increase in the cell volume. Out of 6 proteins, 4 were localised to the ER. CONCLUSIONS This work has identified novel proteins involved in the organisation of the Drosophila early secretory pathway. It contributes to the effort of assigning protein functions to gene annotation in the secretory pathway, and analysis of the MG hits revealed an enrichment of ER proteins. These results suggest a link between ER localisation, aspects of cell metabolism and tER-Golgi structural organisation.
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Affiliation(s)
- Vangelis Kondylis
- Cell microscopy Centre, Department of Cell Biology, UMC Utrecht, The Netherlands
| | - Yang Tang
- Cell microscopy Centre, Department of Cell Biology, UMC Utrecht, The Netherlands
| | - Florian Fuchs
- German Cancer Research Center (DKFZ) and University of Heidelberg, Division Signaling and Functional Genomics, Heidelberg, Germany
| | - Michael Boutros
- German Cancer Research Center (DKFZ) and University of Heidelberg, Division Signaling and Functional Genomics, Heidelberg, Germany
| | - Catherine Rabouille
- Cell microscopy Centre, Department of Cell Biology, UMC Utrecht, The Netherlands
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Kramer JM, Kochinke K, Oortveld MAW, Marks H, Kramer D, de Jong EK, Asztalos Z, Westwood JT, Stunnenberg HG, Sokolowski MB, Keleman K, Zhou H, van Bokhoven H, Schenck A. Epigenetic regulation of learning and memory by Drosophila EHMT/G9a. PLoS Biol 2011; 9:e1000569. [PMID: 21245904 PMCID: PMC3014924 DOI: 10.1371/journal.pbio.1000569] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 11/10/2010] [Indexed: 11/18/2022] Open
Abstract
The epigenetic modification of chromatin structure and its effect on complex neuronal processes like learning and memory is an emerging field in neuroscience. However, little is known about the "writers" of the neuronal epigenome and how they lay down the basis for proper cognition. Here, we have dissected the neuronal function of the Drosophila euchromatin histone methyltransferase (EHMT), a member of a conserved protein family that methylates histone 3 at lysine 9 (H3K9). EHMT is widely expressed in the nervous system and other tissues, yet EHMT mutant flies are viable. Neurodevelopmental and behavioral analyses identified EHMT as a regulator of peripheral dendrite development, larval locomotor behavior, non-associative learning, and courtship memory. The requirement for EHMT in memory was mapped to 7B-Gal4 positive cells, which are, in adult brains, predominantly mushroom body neurons. Moreover, memory was restored by EHMT re-expression during adulthood, indicating that cognitive defects are reversible in EHMT mutants. To uncover the underlying molecular mechanisms, we generated genome-wide H3K9 dimethylation profiles by ChIP-seq. Loss of H3K9 dimethylation in EHMT mutants occurs at 5% of the euchromatic genome and is enriched at the 5' and 3' ends of distinct classes of genes that control neuronal and behavioral processes that are corrupted in EHMT mutants. Our study identifies Drosophila EHMT as a key regulator of cognition that orchestrates an epigenetic program featuring classic learning and memory genes. Our findings are relevant to the pathophysiological mechanisms underlying Kleefstra Syndrome, a severe form of intellectual disability caused by mutations in human EHMT1, and have potential therapeutic implications. Our work thus provides novel insights into the epigenetic control of cognition in health and disease.
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Affiliation(s)
- Jamie M. Kramer
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Korinna Kochinke
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Merel A. W. Oortveld
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Hendrik Marks
- Radboud University Nijmegen, Department of Molecular Biology, Nijmegen Centre for Molecular Life Sciences, Faculty of Science, Nijmegen, The Netherlands
| | - Daniela Kramer
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Eiko K. de Jong
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Zoltan Asztalos
- Aktogen Ltd., Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Institute of Biochemistry, Biological Research Center of Hungarian Academy of Sciences, Szeged, Hungary
| | | | - Hendrik G. Stunnenberg
- Radboud University Nijmegen, Department of Molecular Biology, Nijmegen Centre for Molecular Life Sciences, Faculty of Science, Nijmegen, The Netherlands
| | | | | | - Huiqing Zhou
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Hans van Bokhoven
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department of Cognitive Neurosciences, Donders Institute for Brain, Cognition and Behavior; Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- * E-mail: (AS); (HvB)
| | - Annette Schenck
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- * E-mail: (AS); (HvB)
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25
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Chufán EE, De M, Eipper BA, Mains RE, Amzel LM. Amidation of bioactive peptides: the structure of the lyase domain of the amidating enzyme. Structure 2009; 17:965-73. [PMID: 19604476 DOI: 10.1016/j.str.2009.05.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 04/29/2009] [Accepted: 05/01/2009] [Indexed: 11/26/2022]
Abstract
Many neuropeptides and peptide hormones require amidation of their carboxy terminal for full biological activity. The enzyme peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL; EC 4.3.2.5) catalyzes the second and last step of this reaction, N-dealkylation of the peptidyl-alpha-hydroxyglycine to generate the alpha-amidated peptide and glyoxylate. Here we report the X-ray crystal structure of the PAL catalytic core (PALcc) alone and in complex with the nonpeptidic substrate alpha-hydroxyhippuric acid. The structures show that PAL folds as a six-bladed beta-propeller. The active site is formed by a Zn(II) ion coordinated by three histidine residues; the substrate binds to this site with its alpha-hydroxyl group coordinated to the Zn(II) ion. The structures also reveal a tyrosine residue (Tyr(654)) at the active site as the catalytic base for hydroxyl deprotonation, an unusual role for tyrosine. A reaction mechanism is proposed based on this structural data and validated by biochemical analysis of site-directed PALcc mutants.
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Affiliation(s)
- Eduardo E Chufán
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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Nakanishi N, Rahman MM, Sakamoto Y, Takigami T, Kobayashi K, Hori H, Hase T, Park SY, Tsubaki M. Importance of the conserved lysine 83 residue of Zea mays cytochrome b(561) for ascorbate-specific transmembrane electron transfer as revealed by site-directed mutagenesis studies. Biochemistry 2009; 48:10665-78. [PMID: 19803484 DOI: 10.1021/bi9010682] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cytochromes b(561), a novel class of transmembrane electron transport proteins residing in a large variety of eukaryotic cells, have a number of common structural features including six hydrophobic transmembrane alpha-helices and two heme ligation sites. We found that recombinant Zea mays cytochrome b(561) obtained by a heterologous expression system using yeast Pichia pastoris cells could utilize the ascorbate/mondehydroascorbate radical as a physiological electron donor/acceptor. We found further that a concerted proton/electron transfer mechanism might be operative in Z. mays cytochrome b(561) as well upon the electron acceptance from ascorbate to the cytosolic heme center. The well-conserved Lys(83) residue in a cytosolic loop was found to have a very important role(s) for the binding of ascorbate and the succeeding electron transfer via electrostatic interactions based on the analyses of three site-specific mutants, K83A, K83E, and K83D. Further, unusual behavior of the K83A mutant in pulse radiolysis experiments indicated that Lys(83) might also be responsible for the intramolecular electron transfer to the intravesicular heme. On the other hand, pulse radiolysis experiments on two site-specific mutants, S118A and W122A, for the well-conserved residues in the putative monodehydroascorbate radical binding site showed that their electron transfer activities to the monodehydroascorbate radical were very similar to those of the wild-type protein, indicating that Ser(118) and Trp(122) do not have major roles for the redox events on the intravesicular side.
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Affiliation(s)
- Nobuyuki Nakanishi
- Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan
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