1
|
Gao S, Oden PN, Ryan BJ, Yang H, Freudenthal BD, Greenberg MM. Biochemical and Structural Characterization of Fapy•dG Replication by Human DNA Polymerase β. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.15.575758. [PMID: 38293220 PMCID: PMC10827042 DOI: 10.1101/2024.01.15.575758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
N6-(2-deoxy-α,β-D-erythro-pentofuranosyl)-2,6-diamino-4-hydroxy-5-formamido-pyrimidine (Fapy•dG) is formed from a common intermediate and in comparable amounts to the well-studied mutagenic DNA lesion 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OxodGuo). Fapy•dG preferentially gives rise to G → T transversions and G → A transitions. However, the molecular basis by which Fapy•dG is processed by DNA polymerases during this mutagenic process remains poorly understood. To address this we investigated how DNA polymerase β (Pol β), a model mammalian polymerase, bypasses a templating Fapy•dG, inserts Fapy•dGTP, and extends from Fapy•dG at the primer terminus. When Fapy•dG is present in the template, Pol β incorporates TMP less efficiently than either dCMP or dAMP. Kinetic analysis revealed that Fapy•dGTP is a poor substrate but is incorporated ∼3-times more efficiently opposite dA than dC. Extension from Fapy•dG at the 3'-terminus of a nascent primer is inefficient due to the primer terminus being poorly positioned for catalysis. Together these data indicate that mutagenic bypass of Fapy•dG is likely to be the source of the mutagenic effects of the lesion and not Fapy•dGTP. These experiments increase our understanding of the promutagenic effects of Fapy•dG.
Collapse
|
2
|
Li XQ, Elebring M, Dahlén A, Weidolf L. In Vivo Metabolite Profiles of an N-Acetylgalactosamine-Conjugated Antisense Oligonucleotide AZD8233 Using Liquid Chromatography High-Resolution Mass Spectrometry: A Cross-Species Comparison in Animals and Humans. Drug Metab Dispos 2023; 51:1350-1361. [PMID: 37429729 DOI: 10.1124/dmd.123.001370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 07/12/2023] Open
Abstract
AZD8233, a liver-targeting antisense oligonucleotide (ASO), inhibits subtilisin/kexin type 9 protein synthesis. It is a phosphorothioated 3-10-3 gapmer with a central DNA sequence flanked by constrained 2'-O-ethyl 2',4'-bridged nucleic acid (cEt-BNA) wings and conjugated to a triantennary N-acetylgalactosamine (GalNAc) ligand at the 5'-end. Herein we report the biotransformation of AZD8233, as given by liver, kidney, plasma and urine samples, after repeated subcutaneous administration to humans, mice, rats, rabbits, and monkeys. Metabolite profiles were characterized using liquid chromatography high-resolution mass spectrometry. Metabolite formation was consistent across species, mainly comprising hydrolysis of GalNAc sugars, phosphodiester-linker hydrolysis releasing the full-length ASO, and endonuclease-mediated hydrolysis within the central DNA gap followed by exonuclease-mediated 5'- or 3'-degradation. All metabolites contained the 5'- or 3'-cEt-BNA terminus. Most shortmer metabolites had the free terminal alcohol at 5'- and 3'-positions of ribose, although six were found retaining the terminal 5'-phosphorothioate group. GalNAc conjugated shortmer metabolites were also observed in urine. Synthesized metabolite standards were applied for (semi)quantitative metabolite assessment. Intact AZD8233 was the major component in plasma, whereas the unconjugated full-length ASO was predominant in tissues. In plasma, most metabolites were shortmers retaining the 3'-cEt-BNA terminus, whereas metabolites containing the 5'- or 3'-cEt-BNA terminus were detected in both tissues and urine. All metabolites in human plasma were also detected in all nonclinical species, and all human urine metabolites were detected in monkey urine. In general, metabolite profiles in animal species were qualitatively similar and quantitatively exceeded the exposures of the circulating metabolites in humans at the doses studied. SIGNIFICANCE STATEMENT: This study presents metabolite identification and profiling of AZD8233, an N-acetylgalactosamine-conjugated antisense oligonucleotide (ASO), across species. A biotransformation strategy for ASOs was established by utilizing biologic samples collected from toxicology and/or clinical studies and liquid chromatography high-resolution mass spectrometry analysis without conducting bespoke radiolabeled absorption, distribution, metabolism, and excretion studies. The generated biotransformation package was considered adequate by health authorities to progress AZD8233 into a phase 3 program, proving its applicability to future metabolism studies of ASOs in drug development.
Collapse
Affiliation(s)
- Xue-Qing Li
- DMPK, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (X.-Q.L., M.E., L.W.); and Oligonucleotide Discovery, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (A.D.)
| | - Marie Elebring
- DMPK, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (X.-Q.L., M.E., L.W.); and Oligonucleotide Discovery, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (A.D.)
| | - Anders Dahlén
- DMPK, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (X.-Q.L., M.E., L.W.); and Oligonucleotide Discovery, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (A.D.)
| | - Lars Weidolf
- DMPK, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (X.-Q.L., M.E., L.W.); and Oligonucleotide Discovery, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden (A.D.)
| |
Collapse
|
3
|
Jejina A, Ayala Y, Hernández G, Suter B. Role of BicDR in bristle shaft construction, tracheal development, and support of BicD functions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.16.545245. [PMID: 37398393 PMCID: PMC10312712 DOI: 10.1101/2023.06.16.545245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Cell polarization requires asymmetric localization of numerous mRNAs, proteins, and organelles. The movement of cargo towards the minus end of microtubules mostly depends on cytoplasmic dynein motors, which function as multiprotein complexes. In the dynein/dynactin/Bicaudal-D (DDB) transport machinery, Bicaudal-D (BicD) links the cargo to the motor. Here we focus on the role of BicD-related (BicDR) and its contribution to microtubule-dependent transport processes. Drosophila BicDR is required for the normal development of bristles and dorsal trunk tracheae. Together with BicD, it contributes to the organization and stability of the actin cytoskeleton in the not-yet-chitinized bristle shaft and the localization of Spn-F and Rab6 at the distal tip. We show that BicDR supports the function of BicD in bristle development and our results suggest that BicDR transports cargo more locally whereas BicD is more responsible for delivering functional cargo over the long distance to the distal tip. We identified the proteins that interact with BicDR and appear to be BicDR cargo in embryonic tissues. For one of them, EF1γ, we showed that EF1γ genetically interacts with BicD and BicDR in the construction of the bristles.
Collapse
Affiliation(s)
- Aleksandra Jejina
- Institute of Cell Biology, University of Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland
| | - Yeniffer Ayala
- Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer, Instituto Nacional de Cancerologıá (INCan), Mexico City, Mexico
| | - Greco Hernández
- Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer, Instituto Nacional de Cancerologıá (INCan), Mexico City, Mexico
| | - Beat Suter
- Institute of Cell Biology, University of Bern, Switzerland
| |
Collapse
|
4
|
Mitchell D, Ritchey LE, Park H, Babitzke P, Assmann SM, Bevilacqua PC. Glyoxals as in vivo RNA structural probes of guanine base-pairing. RNA (NEW YORK, N.Y.) 2018; 24:114-124. [PMID: 29030489 PMCID: PMC5733565 DOI: 10.1261/rna.064014.117] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 10/10/2017] [Indexed: 05/09/2023]
Abstract
Elucidation of the folded structures that RNA forms in vivo is vital to understanding its functions. Chemical reagents that modify the Watson-Crick (WC) face of unprotected nucleobases are particularly useful in structure elucidation. Dimethyl sulfate penetrates cell membranes and informs on RNA base-pairing and secondary structure but only modifies the WC face of adenines and cytosines. We present glyoxal, methylglyoxal, and phenylglyoxal as potent in vivo reagents that target the WC face of guanines as well as cytosines and adenines. Tests on rice (Oryza sativa) 5.8S rRNA in vitro read out by reverse transcription and gel electrophoresis demonstrate specific modification of almost all guanines in a time- and pH-dependent manner. Subsequent in vivo tests on rice, a eukaryote, and Bacillus subtilis and Escherichia coli, Gram-positive and Gram-negative bacteria, respectively, showed that all three reagents enter living cells without prior membrane permeabilization or pH adjustment of the surrounding media and specifically modify solvent-exposed guanine, cytosine, and adenine residues.
Collapse
Affiliation(s)
- David Mitchell
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Laura E Ritchey
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Hongmarn Park
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Paul Babitzke
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sarah M Assmann
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Philip C Bevilacqua
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| |
Collapse
|
5
|
Alvarez RH, Natal FLN, Ribela MTCP, de Almeida BE, de Oliveira JE, Bartolini P. Physical-chemical and biological characterization of different preparations of equine chorionic gonadotropin. J Vet Sci 2017; 17:459-465. [PMID: 27297410 PMCID: PMC5204023 DOI: 10.4142/jvs.2016.17.4.459] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 03/17/2016] [Accepted: 05/12/2016] [Indexed: 02/05/2023] Open
Abstract
Ovarian stimulation with commercial preparations of equine chorionic gonadotropin (eCG) produces extremely variable responses in domestic animals, ranging from excessive stimulation to practically no stimulation, when applied on the basis of their declared unitage. This study was conducted to analyze four commercial preparations from different manufacturers via reversed-phase HPLC (RP-HPLC) in comparison with a reference preparation and an official International Standard from the World Health Organization. The peaks obtained by this qualitative and quantitative physical–chemical analysis were compared using an in vivo bioassay based on the ovarian weight gain of prepubertal female rats. The RP-HPLC data showed one or two peaks close to a main peak (tR = 27.9 min), which were related to the in vivo bioactivity. Commercial preparations that have this altered peak showed very little or no in vivo activity, as demonstrated by rat ovarian weight and in peripubertal gilts induced to ovulate. Overall, these findings indicate that RP-HPLC can be a rapid and reliable tool to reveal changes in the physicochemical profile of commercial eCG that is apparently related to decreased biological activity of this hormone.
Collapse
Affiliation(s)
| | | | | | - Beatriz Elane de Almeida
- Biotechnology Department, IPEN-CNEN, Cidade Universitária Sao Paulo, 05508-000 São Paulo, Brazil
| | | | - Paolo Bartolini
- Biotechnology Department, IPEN-CNEN, Cidade Universitária Sao Paulo, 05508-000 São Paulo, Brazil
| |
Collapse
|
6
|
Lozano G, Jimenez-Aparicio R, Herrero S, Martinez-Salas E. Fingerprinting the junctions of RNA structure by an open-paddlewheel diruthenium compound. RNA (NEW YORK, N.Y.) 2016; 22:330-8. [PMID: 26759454 PMCID: PMC4748811 DOI: 10.1261/rna.054353.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 12/05/2015] [Indexed: 05/17/2023]
Abstract
RNA function is determined by its structural organization. The RNA structure consists of the combination of distinct secondary structure motifs connected by junctions that play an essential role in RNA folding. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) probing is an established methodology to analyze the secondary structure of long RNA molecules in solution, which provides accurate data about unpaired nucleotides. However, the residues located at the junctions of RNA structures usually remain undetected. Here we report an RNA probing method based on the use of a novel open-paddlewheel diruthenium (OPW-Ru) compound [Ru2Cl2(µ-DPhF)3(DMSO)] (DPhF = N,N'-diphenylformamidinate). This compound has four potential coordination sites in a singular disposition to establish covalent bonds with substrates. As a proof of concept, we have analyzed the reactivity of OPW-Ru toward RNA using two viral internal ribosome entry site (IRES) elements whose function depends on the structural organization of the molecule. Our study suggests that the compound OPW-Ru preferentially attacks at positions located one or two nucleotides away from junctions or bulges of the RNA structure. The OPW-Ru fingerprinting data differ from that obtained by other chemical reagents and provides new information about RNA structure features.
Collapse
Affiliation(s)
- Gloria Lozano
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid 28049, Spain
| | - Reyes Jimenez-Aparicio
- Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Santiago Herrero
- Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain
| | | |
Collapse
|
7
|
Bai Y, Dai X, Harrison A, Johnston C, Chen M. Toward a next-generation atlas of RNA secondary structure. Brief Bioinform 2015; 17:63-77. [PMID: 25922372 DOI: 10.1093/bib/bbv026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Indexed: 12/23/2022] Open
Abstract
RNA structure plays a crucial role in gene maturation, regulation and function. Determining the form and frequency of RNA folds is essential for a better understanding of how RNA exerts its functions. Low-throughput studies have focused on RNA primary sequences and expression levels, but with an emphasis on relatively small numbers of transcripts. However, with the recent advent of high-throughput technologies, it is realistic to begin analyzing RNA secondary structures on a genome-wide scale. Here, we review genome-wide RNA secondary structure profiles as well as advances in computational structure predictions. We further discuss the novel characteristics of RNA secondary structure across messenger RNAs. Probing RNA secondary structure by high-throughput sequencing will enable us to build atlases of RNA secondary structures, an important step in helping us to understand the versatility of RNA functions in diverse cellular processes.
Collapse
|
8
|
Talkish J, May G, Lin Y, Woolford JL, McManus CJ. Mod-seq: high-throughput sequencing for chemical probing of RNA structure. RNA (NEW YORK, N.Y.) 2014; 20:713-20. [PMID: 24664469 PMCID: PMC3988572 DOI: 10.1261/rna.042218.113] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 01/25/2014] [Indexed: 05/19/2023]
Abstract
The functions of RNA molecules are intimately linked to their ability to fold into complex secondary and tertiary structures. Thus, understanding how these molecules fold is essential to determining how they function. Current methods for investigating RNA structure often use small molecules, enzymes, or ions that cleave or modify the RNA in a solvent-accessible manner. While these methods have been invaluable to understanding RNA structure, they can be fairly labor intensive and often focus on short regions of single RNAs. Here we present a new method (Mod-seq) and data analysis pipeline (Mod-seeker) for assaying the structure of RNAs by high-throughput sequencing. This technique can be utilized both in vivo and in vitro, with any small molecule that modifies RNA and consequently impedes reverse transcriptase. As proof-of-principle, we used dimethyl sulfate (DMS) to probe the in vivo structure of total cellular RNAs in Saccharomyces cerevisiae. Mod-seq analysis simultaneously revealed secondary structural information for all four ribosomal RNAs and 32 additional noncoding RNAs. We further show that Mod-seq can be used to detect structural changes in 5.8S and 25S rRNAs in the absence of ribosomal protein L26, correctly identifying its binding site on the ribosome. While this method is applicable to RNAs of any length, its high-throughput nature makes Mod-seq ideal for studying long RNAs and complex RNA mixtures.
Collapse
Affiliation(s)
- Jason Talkish
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Gemma May
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Yizhu Lin
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - John L. Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - C. Joel McManus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
- Corresponding authorE-mail
| |
Collapse
|
9
|
Dalby AB, Goodrich KJ, Pfingsten JS, Cech TR. RNA recognition by the DNA end-binding Ku heterodimer. RNA (NEW YORK, N.Y.) 2013; 19:841-51. [PMID: 23610127 PMCID: PMC3683917 DOI: 10.1261/rna.038703.113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Most nucleic acid-binding proteins selectively bind either DNA or RNA, but not both nucleic acids. The Saccharomyces cerevisiae Ku heterodimer is unusual in that it has two very different biologically relevant binding modes: (1) Ku is a sequence-nonspecific double-stranded DNA end-binding protein with prominent roles in nonhomologous end-joining and telomeric capping, and (2) Ku associates with a specific stem-loop of TLC1, the RNA subunit of budding yeast telomerase, and is necessary for proper nuclear localization of this ribonucleoprotein enzyme. TLC1 RNA-binding and dsDNA-binding are mutually exclusive, so they may be mediated by the same site on Ku. Although dsDNA binding by Ku is well studied, much less is known about what features of an RNA hairpin enable specific recognition by Ku. To address this question, we localized the Ku-binding site of the TLC1 hairpin with single-nucleotide resolution using phosphorothioate footprinting, used chemical modification to identify an unpredicted motif within the hairpin secondary structure, and carried out mutagenesis of the stem-loop to ascertain the critical elements within the RNA that permit Ku binding. Finally, we provide evidence that the Ku-binding site is present in additional budding yeast telomerase RNAs and discuss the possibility that RNA binding is a conserved function of the Ku heterodimer.
Collapse
|
10
|
Carte J, Pfister NT, Compton MM, Terns RM, Terns MP. Binding and cleavage of CRISPR RNA by Cas6. RNA (NEW YORK, N.Y.) 2010; 16:2181-8. [PMID: 20884784 PMCID: PMC2957057 DOI: 10.1261/rna.2230110] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The CRISPR-Cas system provides many prokaryotes with acquired resistance to viruses and other mobile genetic elements. The core components of this defense system are small, host-encoded prokaryotic silencing (psi)RNAs and Cas (CRISPR-associated) proteins. Invader-derived sequences within the psiRNAs guide Cas effector proteins to recognize and silence invader nucleic acids. Critical for CRISPR-Cas defense is processing of the psiRNAs from the primary transcripts of the host CRISPR (clustered regularly interspaced short palindromic repeat) locus. Cas6, a previously identified endoribonuclease present in a wide range of prokaryotes with the CRISPR-Cas system, binds and cleaves within the repeat sequences that separate the individual invader targeting elements in the CRISPR locus transcript. In the present study, we investigated several key aspects of the mechanism of function of Cas6 in psiRNA biogenesis. RNA footprinting reveals that Pyrococcus furiosus Cas6 binds to a 7-nt (nucleotide) sequence near the 5' end of the CRISPR RNA repeat sequence, 14 nt upstream of the Cas6 cleavage site. In addition, analysis of the cleavage activity of P. furiosus Cas6 proteins with mutations at conserved residues suggests that a triad comprised of Tyr31, His46, and Lys52 plays a critical role in catalysis, consistent with a possible general acid-base RNA cleavage mechanism for Cas6. Finally, we show that P. furiosus Cas6 remains stably associated with its cleavage products, suggesting additional roles for Cas6 in psiRNA biogenesis.
Collapse
Affiliation(s)
- Jason Carte
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | | | | | | | | |
Collapse
|
11
|
Charette JM, Baserga SJ. The DEAD-box RNA helicase-like Utp25 is an SSU processome component. RNA (NEW YORK, N.Y.) 2010; 16:2156-69. [PMID: 20884785 PMCID: PMC2957055 DOI: 10.1261/rna.2359810] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The SSU processome is a large ribonucleoprotein complex consisting of the U3 snoRNA and at least 43 proteins. A database search, initiated in an effort to discover additional SSU processome components, identified the uncharacterized, conserved and essential yeast nucleolar protein YIL091C/UTP25 as one such candidate. The C-terminal DUF1253 motif, a domain of unknown function, displays limited sequence similarity to DEAD-box RNA helicases. In the absence of the conserved DEAD-box sequence, motif Ia is the only clearly identifiable helicase element. Since the yeast homolog is nucleolar and interacts with components of the SSU processome, we examined its role in pre-rRNA processing. Genetic depletion of Utp25 resulted in slowed growth. Northern analysis of pre-rRNA revealed an 18S rRNA maturation defect at sites A₀, A₁, and A₂. Coimmunoprecipitation confirmed association with U3 snoRNA and with Mpp10, and with components of the t-Utp/UtpA, UtpB, and U3 snoRNP subcomplexes. Mutation of the conserved motif Ia residues resulted in no discernable temperature-sensitive or cold-sensitive growth defects, implying that this motif is dispensable for Utp25 function. A yeast two-hybrid screen of Utp25 against other SSU processome components revealed several interacting proteins, including Mpp10, Utp3, and Utp21, thereby identifying the first interactions among the different subcomplexes of the SSU processome. Furthermore, the DUF1253 domain is required and sufficient for the interaction of Utp25 with Utp3. Thus, Utp25 is a novel SSU processome component that, along with Utp3, forms the first identified interactions among the different SSU processome subcomplexes.
Collapse
Affiliation(s)
- J Michael Charette
- Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | | |
Collapse
|
12
|
Almeida B, Oliveira J, Carvalho C, Dalmora S, Bartolini P, Ribela M. Analysis of human luteinizing hormone and human chorionic gonadotropin preparations of different origins by reversed-phase high-performance liquid chromatography. J Pharm Biomed Anal 2010; 53:90-7. [DOI: 10.1016/j.jpba.2010.03.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 03/09/2010] [Accepted: 03/10/2010] [Indexed: 12/21/2022]
|
13
|
Song LY, Lu WX, Hu J, Zhang Y, Yin WB, Chen YH, Hao ST, Wang BL, Wang RRC, Hu ZM. Identification and functional analysis of the genes encoding Delta6-desaturase from Ribes nigrum. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1827-38. [PMID: 20231328 PMCID: PMC2852672 DOI: 10.1093/jxb/erq051] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2009] [Revised: 02/09/2010] [Accepted: 02/16/2010] [Indexed: 05/18/2023]
Abstract
Gamma-linolenic acid (gamma-linolenic acid, GLA; C18:3 Delta(6, 9, 12)) belongs to the omega-6 family and exists primarily in several plant oils, such as evening primrose oil, blackcurrant oil, and borage oil. Delta(6)-desaturase is a key enzyme involved in the synthesis of GLA. There have been no previous reports on the genes encoding Delta(6)-desaturase in blackcurrant (Ribes nigrum L.). In this research, five nearly identical copies of Delta(6)-desaturase gene-like sequences, named RnD8A, RnD8B, RnD6C, RnD6D, and RnD6E, were isolated from blackcurrant. Heterologous expression in Saccharomyces cerevisiae and/or Arabidopsis thaliana confirmed that RnD6C/D/E were Delta(6)-desaturases that could use both alpha-linolenic acids (ALA; C18:3 Delta(9,12,15)) and linoleic acid (LA; C18:2 Delta(9,12)) precursors in vivo, whereas RnD8A/B were Delta(8)-sphingolipid desaturases. Expression of GFP tagged with RnD6C/D/E showed that blackcurrant Delta(6)-desaturases were located in the mitochondrion (MIT) in yeast and the endoplasmic reticulum (ER) in tobacco. GC-MS results showed that blackcurrant accumulated GLA and octadecatetraenoic acids (OTA; C18:4 Delta(6,9,12,15)) mainly in seeds and a little in other organs and tissues. RT-PCR results showed that RnD6C and RnD6E were expressed in all the tissues at a low level, whereas RnD6D was expressed at a high level only in seeds, leading to the accumulation of GLA and OTA in seeds. This research provides new insights to our understanding of GLA synthesis and accumulation in plants and the evolutionary relationship of this class of desaturases, and new clues as to the amino acid determinants which define precise enzyme activity.
Collapse
Affiliation(s)
- Li-Ying Song
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
- Graduate University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Wan-Xiang Lu
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
- College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400716, China
| | - Jun Hu
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
| | - Yan Zhang
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
| | - Wei-Bo Yin
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
| | - Yu-Hong Chen
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
| | - Shan-Ting Hao
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
| | - Bai-Lin Wang
- Horticulture Division, Heilongjiang Agriculture Academy, Harbin 150069, China
| | - Richard R-C Wang
- USDA-ARS, FRRL, Utah State University, Logan, UT 84322-6300, USA
| | - Zan-Min Hu
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
| |
Collapse
|
14
|
Quarrier S, Martin JS, Davis-Neulander L, Beauregard A, Laederach A. Evaluation of the information content of RNA structure mapping data for secondary structure prediction. RNA (NEW YORK, N.Y.) 2010; 16:1108-17. [PMID: 20413617 PMCID: PMC2874162 DOI: 10.1261/rna.1988510] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 02/20/2010] [Indexed: 05/21/2023]
Abstract
Structure mapping experiments (using probes such as dimethyl sulfate [DMS], kethoxal, and T1 and V1 RNases) are used to determine the secondary structures of RNA molecules. The process is iterative, combining the results of several probes with constrained minimum free-energy calculations to produce a model of the structure. We aim to evaluate whether particular probes provide more structural information, and specifically, how noise in the data affects the predictions. Our approach involves generating "decoy" RNA structures (using the sFold Boltzmann sampling procedure) and evaluating whether we are able to identify the correct structure from this ensemble of structures. We show that with perfect information, we are always able to identify the optimal structure for five RNAs of known structure. We then collected orthogonal structure mapping data (DMS and RNase T1 digest) under several solution conditions using our high-throughput capillary automated footprinting analysis (CAFA) technique on two group I introns of known structure. Analysis of these data reveals the error rates in the data under optimal (low salt) and suboptimal solution conditions (high MgCl(2)). We show that despite these errors, our computational approach is less sensitive to experimental noise than traditional constraint-based structure prediction algorithms. Finally, we propose a novel approach for visualizing the interaction of chemical and enzymatic mapping data with RNA structure. We project the data onto the first two dimensions of a multidimensional scaling of the sFold-generated decoy structures. We are able to directly visualize the structural information content of structure mapping data and reconcile multiple data sets.
Collapse
Affiliation(s)
- Scott Quarrier
- Biomedical Sciences Program, University at Albany, Albany, New York 12208, USA
| | | | | | | | | |
Collapse
|
15
|
Khan NA, Vierboom MPM, van Holten-Neelen C, Breedveld E, Zuiderwijk-Sick E, Khan A, Kondova I, Braskamp G, Savelkoul HFJ, Dik WA, 't Hart BA, Benner R. Mitigation of septic shock in mice and rhesus monkeys by human chorionic gonadotrophin-related oligopeptides. Clin Exp Immunol 2010; 160:466-78. [PMID: 20345979 DOI: 10.1111/j.1365-2249.2010.04112.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The marked improvement of several immune-mediated inflammatory diseases during pregnancy has drawn attention to pregnancy hormones as potential therapeutics for such disorders. Low molecular weight fractions derived from the pregnancy hormone human chorionic gonadotrophin (hCG) have remarkable potent immunosuppressive effects in mouse models of diabetes and septic shock. Based on these data we have designed a set of oligopeptides related to the primary structure of hCG and tested these in models of septic shock in mice and rhesus monkeys. We demonstrate that mice exposed to lipopolysaccharide (LPS) and treated subsequently with selected tri-, tetra-, penta- and hepta-meric oligopeptides (i.e. MTR, VVC, MTRV, LQGV, AQGV, VLPALP, VLPALPQ) are protected against fatal LPS-induced septic shock. Moreover, administration of a cocktail of three selected oligopeptides (LQGV, AQGV and VLPALP) improved the pathological features markedly and nearly improved haemodynamic parameters associated with intravenous Escherichia coli-induced septic shock in rhesus monkeys. These data indicate that the designed hCG-related oligopeptides may present a potential treatment for the initial hyperdynamic phase of septic shock in humans.
Collapse
Affiliation(s)
- N A Khan
- Department of Immunology, Erasmus MC University Medical Center, Rotterdam, the Netherlands
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Moreno R, Marzi S, Romby P, Rojo F. The Crc global regulator binds to an unpaired A-rich motif at the Pseudomonas putida alkS mRNA coding sequence and inhibits translation initiation. Nucleic Acids Res 2010; 37:7678-90. [PMID: 19825982 PMCID: PMC2794181 DOI: 10.1093/nar/gkp825] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Crc is a key global translational regulator in Pseudomonads that orchestrates the hierarchy of induction of several catabolic pathways for amino acids, sugars, hydrocarbons or aromatic compounds. In the presence of amino acids, which are preferred carbon sources, Crc inhibits translation of the Pseudomonas putida alkS and benR mRNAs, which code for transcriptional regulators of genes required to assimilate alkanes (hydrocarbons) and benzoate (an aromatic compound), respectively. Crc binds to the 5′-end of these mRNAs, but the sequence and/or structure recognized, and the way in which it inhibits translation, were unknown. We have determined the secondary structure of the alkS mRNA 5′-end through its sensitivity to several ribonucleases and chemical reagents. Footprinting and band-shift assays using variant alkS mRNAs have shown that Crc specifically binds to a short unpaired A-rich sequence located adjacent to the alkS AUG start codon. This interaction is stable enough to prevent formation of the translational initiation complex. A similar Crc-binding site was localized at benR mRNA, upstream of the Shine–Dalgarno sequence. This allowed predicting binding sites at other Crc-regulated genes, deriving a consensus sequence that will help to validate new Crc targets and to discriminate between direct and indirect effects of this regulator.
Collapse
Affiliation(s)
- Renata Moreno
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Campus UAM, Cantoblanco, 28049 Madrid, Spain
| | | | | | | |
Collapse
|
17
|
Khademi F, Hamzehee K, Mostafaie A, Hajihossaini R. Purification of three major forms of β-hCG from urine and production of polyclonal antibodies against them. Clin Biochem 2009; 42:1476-82. [DOI: 10.1016/j.clinbiochem.2009.05.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 05/20/2009] [Accepted: 05/25/2009] [Indexed: 11/30/2022]
|
18
|
Khan NA, Susa D, van den Berg JW, Huisman M, Ameling MH, van den Engel S, Roest HP, Ijzermans JNM, Dik WA, Benner R, de Bruin RWF. Amelioration of renal ischaemia-reperfusion injury by synthetic oligopeptides related to human chorionic gonadotropin. Nephrol Dial Transplant 2009; 24:2701-8. [PMID: 19633318 DOI: 10.1093/ndt/gfp369] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND We have previously reported that small synthetic oligopeptides related to human beta-chorionic gonadotropin (beta-hCG) can reduce inflammation. Here we investigated whether such oligopeptides can reduce renal ischaemia-reperfusion injury in the mouse. METHODS Ten different oligopeptides were administered 1 min before induction of renal ischaemia and 1 min before reperfusion. RESULTS Survival at 72 h post-reperfusion was significantly higher in mice treated with oligopeptides MTRV, LQG, VLPALPQ or AQGV as compared to placebo-treated mice. Some oligopeptides were more effective than others. AQGV completely prevented mortality and best preserved kidney function. Next, AQGV was tested in a dose-escalating study in a range of 0.3-30 mg/kg. A survival gain was observed with all doses. Improvement of kidney function was observed from 1 mg/kg. Highest survival and best preserved kidney function were observed at 3 and 10 mg/kg. Upon treatment with AQGV, a significantly lower influx of neutrophils was found, apoptosis was decreased, whereas tubular epithelial cell proliferation was significantly increased at 24 h post-reperfusion. Serum levels of TNF-alpha, INF-gamma, IL-6 and IL-10 were significantly decreased at 24 h post-reperfusion. E-selectin mRNA levels in kidneys were significantly decreased at 6 h post-reperfusion. AQGV did not reduce mortality when treatment was started after reperfusion. CONCLUSIONS This study shows that small oligopeptides related to the primary structure of beta-hCG, especially AQGV, are promising potential drugs for preventing the development of renal ischaemia-reperfusion injury.
Collapse
Affiliation(s)
- Nisar A Khan
- Department of Immunology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
The need for a quantitative urine hCG assay. Clin Biochem 2009; 42:676-83. [DOI: 10.1016/j.clinbiochem.2008.10.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 10/23/2008] [Accepted: 10/24/2008] [Indexed: 12/20/2022]
|
20
|
Villa NY, Kupchak BR, Garitaonandia I, Smith JL, Alonso E, Alford C, Cowart LA, Hannun YA, Lyons TJ. Sphingolipids function as downstream effectors of a fungal PAQR. Mol Pharmacol 2008; 75:866-75. [PMID: 19066337 DOI: 10.1124/mol.108.049809] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The Izh2p protein from Saccharomyces cerevisiae belongs to the newly characterized progestin and adipoQ receptor (PAQR) superfamily of receptors whose mechanism of signal transduction is still unknown. Izh2p functions as a receptor for the plant PR-5 defensin osmotin and has pleiotropic effects on cellular biochemistry. One example of this pleiotropy is the Izh2p-dependent repression of FET3, a gene involved in iron-uptake. Although the physiological purpose of FET3 repression by Izh2p is a matter of speculation, it provides a reporter with which to probe the mechanism of signal transduction by this novel class of receptor. Receptors in the PAQR family share sequence similarity with enzymes involved in ceramide metabolism, which led to the hypothesis that sphingolipids are involved in Izh2p-dependent signaling. In this study, we demonstrate that drugs affecting sphingolipid metabolism, such as d-erythro-MAPP and myriocin, inhibit the effect of Izh2p on FET3. We also show that Izh2p causes an increase in steady-state levels of sphingoid base. Moreover, we show that Izh2p-independent increases in sphingoid bases recapitulate the effect of Izh2p on FET3. Finally, our data indicate that the Pkh1p and Pkh2p sphingoid base-sensing kinases are essential components of the Izh2p-dependent signaling pathway. In conclusion, our data indicate that Izh2p produces sphingoid bases and that these bioactive lipids probably function as the second messenger responsible for the effect of Izh2p on FET3.
Collapse
Affiliation(s)
- Nancy Y Villa
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Sinck L, Richer D, Howard J, Alexander M, Purcell DFJ, Marquet R, Paillart JC. In vitro dimerization of human immunodeficiency virus type 1 (HIV-1) spliced RNAs. RNA (NEW YORK, N.Y.) 2007; 13:2141-2150. [PMID: 17925344 PMCID: PMC2080610 DOI: 10.1261/rna.678307] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 08/28/2007] [Indexed: 05/25/2023]
Abstract
The human immunodeficiency virus type 1 (HIV-1) packages its genomic RNA as a dimer of homologous RNA molecules that has to be selected among a multitude of cellular and viral RNAs. Interestingly, spliced viral mRNAs are packaged into viral particles with a relatively low efficiency despite the fact that they contain most of the extended packaging signal found in the 5' untranslated region of the genomic RNA, including the dimerization initiation site (DIS). As a consequence, HIV-1 spliced viral RNAs can theoretically homodimerize and heterodimerize with the genomic RNA, and thus they should directly compete with genomic RNA for packaging. To shed light on this issue, we investigated for the first time the in vitro dimerization properties of spliced HIV-1 RNAs. We found that singly spliced (env, vpr) and multispliced (tat, rev, and nef) RNA fragments are able to dimerize in vitro, and to efficiently form heterodimers with genomic RNA. Chemical probing experiments and inhibition of RNA dimerization by an antisense oligonucleotide directed against the DIS indicated that the DIS is structurally functional in spliced HIV-1 RNA, and that RNA dimerization occurs through a loop-loop interaction. In addition, by combining in vitro transcription and dimerization assays, we show that heterodimers can be efficiently formed only when the two RNA fragments are synthesized simultaneously, in the same environment. Together, our results support a model in which RNA dimerization would occur during transcription in the nucleus and could thus play a major role in splicing, transport, and localization of HIV-1 RNA.
Collapse
Affiliation(s)
- Lucile Sinck
- Architecture et Réactivité de l'ARN, Université Louis Pasteur, CNRS, IBMC, 67084, Strasbourg cedex, France
| | | | | | | | | | | | | |
Collapse
|
22
|
Andreev DE, Fernandez-Miragall O, Ramajo J, Dmitriev SE, Terenin IM, Martinez-Salas E, Shatsky IN. Differential factor requirement to assemble translation initiation complexes at the alternative start codons of foot-and-mouth disease virus RNA. RNA (NEW YORK, N.Y.) 2007; 13:1366-74. [PMID: 17592045 PMCID: PMC1924898 DOI: 10.1261/rna.469707] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The foot-and-mouth disease virus (FMDV) RNA contains two in-frame AUG codons separated by 84 nt that direct translation initiation of the viral polyprotein. The mechanism of initiation at the IRES-proximal AUG codon (AUG1) has been previously analyzed, whereas no data on factor requirements for AUG2 have been reported. Here, using the method of 48S translation initiation complex reconstitution, we show that eIF1 is indispensable in forming the 48S initiation complex at AUG2. In contrast, it reduces the assembly of this complex at AUG1. Stabilization of a stem-loop between the initiation triplets induces a small decrease in the toeprint intensity at AUG2, accompanied by an increase in the AUG1/AUG2 ratio as well as a moderate reduction of protein synthesis initiated at AUG2 in transfected cells. PTB and ITAF45 exerted an additive positive effect on the 48S complex at AUG2, although a substantial reconstitution on both AUGs occurs on omission of either of these proteins. Relative to the beta-globin mRNA, the 48S complex formation at AUG1 and AUG2 is slow and occurs with the same kinetics as revealed by the "kinetic" toeprint assay. Mutation of AUG1 to AUA does not abrogate protein synthesis in transfected cells, and has no effect on the rate of the 48S complex formation at AUG2. We conclude that the AUG2 initiation region is selected independently of 48S complex formation at the upstream AUG1. The kinetic toeprint assay also shows that cap-dependent assembly of the 48S complex in vitro occurs faster than the FMDV IRES-mediated complex assembly.
Collapse
Affiliation(s)
- Dmitri E Andreev
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | | | | | | | | | | | | |
Collapse
|
23
|
Reynolds A, Anderson EM, Vermeulen A, Fedorov Y, Robinson K, Leake D, Karpilow J, Marshall WS, Khvorova A. Induction of the interferon response by siRNA is cell type- and duplex length-dependent. RNA (NEW YORK, N.Y.) 2006; 12:988-93. [PMID: 16611941 PMCID: PMC1464853 DOI: 10.1261/rna.2340906] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Long (27-29-bp dsRNA) Dicer-dependent substrates have been identified as potent mediators of RNAi-induced gene knockdown in HEK293 and HeLa cells. As the lengths of these molecules are reported to be below the threshold generally regarded as necessary for induction of the mammalian interferon (IFN) response, these long siRNA are being considered as RNAi substrates in both research and therapeutic settings. In this report, we demonstrate that >23-bp dsRNA can influence cell viability and induce a potent IFN response (highlighted by a strong up-regulation of the dsRNA receptor, Toll-like receptor 3) in a cell type-specific manner. This finding suggests that the length threshold for siRNA induction of the IFN response is not fixed but instead varies significantly among different cell types. Given the diversity of cell types that comprise whole organisms, these findings suggest great care should be taken when considering length variations of dsRNA molecules for RNAi experimentation, especially in therapeutic applications.
Collapse
|
24
|
Yu LE, Koslowsky DJ. Interactions of mRNAs and gRNAs involved in trypanosome mitochondrial RNA editing: structure probing of a gRNA bound to its cognate mRNA. RNA (NEW YORK, N.Y.) 2006; 12:1050-60. [PMID: 16618968 PMCID: PMC1464861 DOI: 10.1261/rna.3406] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 03/08/2006] [Indexed: 05/08/2023]
Abstract
Expression of mitochondrial genes in Trypanosoma brucei requires RNA editing of its mRNA transcripts. During editing, uridylates are precisely inserted and deleted as directed by the gRNA template to create the protein open reading frame. This process involves the bimolecular interaction of the gRNA with its cognate pre-edited mRNA and the assembly of a protein complex with the enzymatic machinery required. While a considerable amount of work has been done identifying the protein components of the editing complex, very little is known about how a functional editosome is assembled. In addition, the importance of RNA structure in establishing a functional editing complex is poorly understood. Work in our lab suggests that different mRNA/gRNA pairs can form similar secondary structures suggesting that a common core architecture may be important for editosome recognition and function. Using solution structure probing, we have investigated the structure of the initiating gRNA, gCYb-558, in the mRNA/gRNA complex with pre-edited apocytochrome b mRNA. Our data indicate that the stem-loop formed by the guiding region of the gRNA alone is maintained in its interaction with the pre-edited message. In addition, our data suggest that a gRNA stem-loop structure is maintained through the first few editing events by the use of alternative base-pairing with the U-tail.
Collapse
Affiliation(s)
- Laura E Yu
- Cell and Molecular Biology Program, Michigan State University, East Lansing, 48824, USA
| | | |
Collapse
|
25
|
Wilson TJ, Ouellet J, Zhao ZY, Harusawa S, Araki L, Kurihara T, Lilley DMJ. Nucleobase catalysis in the hairpin ribozyme. RNA (NEW YORK, N.Y.) 2006; 12:980-7. [PMID: 16601203 PMCID: PMC1464849 DOI: 10.1261/rna.11706] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
RNA catalysis is important in the processing and translation of RNA molecules, yet the mechanisms of catalysis are still unclear in most cases. We have studied the role of nucleobase catalysis in the hairpin ribozyme, where the scissile phosphate is juxtaposed between guanine and adenine bases. We show that a modified ribozyme in which guanine 8 has been substituted by an imidazole base is active in both cleavage and ligation, with ligation rates 10-fold faster than cleavage. The rates of both reactions exhibit bell-shaped dependence on pH, with pK(a) values of 5.7 +/- 0.1 and 7.7 +/- 0.1 for cleavage and 6.1 +/- 0.3 and 6.9 +/- 0.3 for ligation. The data provide good evidence for general acid-base catalysis by the nucleobases.
Collapse
Affiliation(s)
- Timothy J Wilson
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee
| | | | | | | | | | | | | |
Collapse
|
26
|
Fernández-Miragall O, Ramos R, Ramajo J, Martínez-Salas E. Evidence of reciprocal tertiary interactions between conserved motifs involved in organizing RNA structure essential for internal initiation of translation. RNA (NEW YORK, N.Y.) 2006; 12:223-34. [PMID: 16373480 PMCID: PMC1370902 DOI: 10.1261/rna.2153206] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Internal ribosome entry site (IRES) elements consist of highly structured RNA regions that determine internal initiation of translation. We have previously shown that the foot-and-mouth disease virus (FMDV) IRES contains a GNRA tetraloop spanning residues G178UAA181. Here we show that tertiary RNA interactions dependent on the GNRA motif determine the structural organization of the central domain. By using mutational analysis in combination with RNA probing, we have identified distant reciprocal interactions between the GNRA motif and the invariant region G240CACG244, termed motif A. Mutations in motif A caused a decrease in IRES activity as severe as the GUAG substitution in the GNRA motif. Substitutions in either GNRA or motif A sequences induced a common reorganization around the conserved R199AAA202 stem-loop, suggesting that the latter contributes to stabilize the GNRA-motif A interaction. This finding was also consistent with a significant increase in the efficiency of RNA-RNA interactions determined in gel shift assays using as probe the hairpin that contains the GNRA motif compared to a transcript encompassing the entire apical region of the central domain. Thus, we propose that the central domain of the FMDV IRES contains a structural conformation essential for IRES activity stabilized by a tertiary contact involving residues in the GNRA tetraloop and motif A conserved sequences.
Collapse
|
27
|
Turner B, Melcher SE, Wilson TJ, Norman DG, Lilley DMJ. Induced fit of RNA on binding the L7Ae protein to the kink-turn motif. RNA (NEW YORK, N.Y.) 2005; 11:1192-200. [PMID: 15987806 PMCID: PMC1370803 DOI: 10.1261/rna.2680605] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The kink-turn is a widespread motif in RNA consisting of a three-nucleotide bulge flanked on one side by consecutive A3G mismatches. Important examples are found in the ribosome, U4 RNA, and in snoRNAs involved in RNA modification. The motif is a common protein binding site, and the RNA has been found to adopt a tightly kinked conformation in crystal structures. However, in free solution there is a dynamic exchange between kinked and extended conformations, with the equilibrium driven toward the kinked form by the addition of metal ions. Here we used fluorescence resonance energy transfer (FRET) to show that the L7Ae protein of Archaeoglobus fulgidus binds to RNA containing a kink-turn with nanomolar affinity, and induces folding into the tightly kinked conformation even in the absence of metal ions. Thus this RNA may act as a relatively flexible hinge during RNA folding, until fixed into its ultimate kinked structure by the binding of L7 or related protein.
Collapse
Affiliation(s)
- Ben Turner
- Cancer Research-UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, UK
| | | | | | | | | |
Collapse
|
28
|
Abstract
This paper summarizes studies on antibody formation in the bone marrow and the suppressive effects of intravenous immunization with allogeneic blood cells on T-cell function in mice. The latter studies were extended by employing the limiting dilution culture system developed in Ivan Lefkovits' laboratory and implemented in collaboration with Lucien Aarden. Thereby, the functional data were complemented with frequencies of alloantigen-activated helper (Th) and suppressor T cells after intravenous alloimmunization. These results led the Rotterdam group to studies on the prevention of rejection of the foetal 'allograft'. Th cells are central in foetal allograft rejection and pregnancy success. Characteristic for human pregnancy is the production of the glycoprotein chorionic gonadotropin (hCG) hormone. The in vivo liberated peptide fragments originating from nicking of the sequence MTRVLQGVLPALPQ in the beta-chain of hCG were considered for their immunoregulating capacity related to pregnancy success. These peptides - prepared synthetically - (MTR, MTRV, LQG, LQGV, VLPALP and others) indeed showed a remarkable spectrum of biological effects (e.g. modulation of angiogenesis, inhibition of septic shock syndrome, prevention of diabetes and reduction of ischaemia-reperfusion damage). The paper interprets and generalizes these findings and projects them into various research directions, especially towards the proteomics framework studies built up in Ivan Lefkovits' laboratory in the nineties. During the time period, when Ivan spent a mini-sabbatical in Rotterdam (months after closing down the BII) more detailed discussions were intiated. This paper is meant to keep the discussions between the involved research groups going on.
Collapse
Affiliation(s)
- R Benner
- Department of Immunology, Erasmus MC-University Medical Center Rotterdam, Rotterdam, The Netherlands.
| | | |
Collapse
|
29
|
Woolf PJ, Prudhomme W, Daheron L, Daley GQ, Lauffenburger DA. Bayesian analysis of signaling networks governing embryonic stem cell fate decisions. Bioinformatics 2004; 21:741-53. [PMID: 15479714 DOI: 10.1093/bioinformatics/bti056] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
MOTIVATION Signaling events that direct mouse embryonic stem (ES) cell self-renewal and differentiation are complex and accordingly difficult to understand in an integrated manner. We address this problem by adapting a Bayesian network learning algorithm to model proteomic signaling data for ES cell fate responses to external cues. Using this model we were able to characterize the signaling pathway influences as quantitative, logic-circuit type interactions. Our experimental dataset includes measurements for 28 signaling protein phosphorylation states across 16 different factorial combinations of cytokine and matrix stimuli as reported previously. RESULTS The Bayesian network modeling approach allows us to uncover previously reported signaling activities related to mouse ES cell self-renewal, such as the roles of LIF and STAT3 in maintaining undifferentiated ES cell populations. Furthermore, the network predicts novel influences such as between ERK phosphorylation and differentiation, or RAF phosphorylation and differentiated cell proliferation. Visualization of the influences detected by the Bayesian network provides intuition about the underlying physiology of the signaling pathways. We demonstrate that the Bayesian networks can capture the linear, nonlinear and multistate logic interactions that connect extracellular cues, intracellular signals and consequent cell functional responses.
Collapse
Affiliation(s)
- Peter J Woolf
- Department of Chemical Engineering, University of Michigan, Room 3320, G. G. Brown Building, 2300 Hayward Street, Ann Arbor, MI 48109-2125, USA.
| | | | | | | | | |
Collapse
|
30
|
Penedo JC, Wilson TJ, Jayasena SD, Khvorova A, Lilley DMJ. Folding of the natural hammerhead ribozyme is enhanced by interaction of auxiliary elements. RNA (NEW YORK, N.Y.) 2004; 10:880-8. [PMID: 15100442 PMCID: PMC1370577 DOI: 10.1261/rna.5268404] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Accepted: 02/09/2004] [Indexed: 05/18/2023]
Abstract
It has been shown that the activity of the hammerhead ribozyme at microM magnesium ion concentrations is markedly increased by the inclusion of loops in helices I and II. We have studied the effect of such loops on the magnesium ion-induced folding of the ribozyme, using fluorescence resonance energy transfer. We find that with the loops in place, folding into the active conformation occurs in a single step, in the microM range of magnesium ion concentration. Disruption of the loop-loop interaction leads to a reversion to two-step folding, with the second stage requiring mM concentrations of magnesium ion. Sodium ions also promote the folding of the natural form of the ribozyme at high concentrations, but the folding occurs as a two-stage process. The loops clearly act as important auxiliary elements in the function of the ribozyme, permitting folding to occur efficiently under physiological conditions.
Collapse
Affiliation(s)
- J Carlos Penedo
- Cancer Research UK Nucleic Acid Structure Research Group, Department of Biochemistry, The University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, United Kingdom
| | | | | | | | | |
Collapse
|
31
|
Silverman SK. Practical and general synthesis of 5'-adenylated RNA (5'-AppRNA). RNA (NEW YORK, N.Y.) 2004; 10:731-46. [PMID: 15037782 PMCID: PMC1370563 DOI: 10.1261/rna.5247704] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Accepted: 01/12/2004] [Indexed: 05/22/2023]
Abstract
A simple strategy is reported for 5'-adenylation of nearly any RNA sequence of indefinite length. The 5'-adenylated product (5'-AppRNA) is an activated RNA that is structurally similar to 5'-triphosphorylated RNA, which is usually prepared by in vitro transcription using T7 RNA polymerase. In the new 5'-adenylation strategy, the RNA substrate is first 5'-monophosphorylated either by T4 polynucleotide kinase, by in vitro transcription in the presence of excess GMP, or by appropriate derivatization during solid-phase synthesis. The RNA is then 5'-adenylated using ATP and T4 RNA ligase, in an interrupted version of the natural adenylation-ligation mechanism by which T4 RNA ligase joins two RNA substrates. Here, the final ligation step of the mechanism is inhibited with complementary DNA blocking oligonucleotide(s) that permit adenylation to occur with good yield. The 5'-AppRNA products of this approach should be valuable as activated RNAs for in vitro selection experiments as an alternative to 5'-triphosphorylated RNAs, among other likely applications. The 5'-terminal nucleotide of an RNA substrate to be adenylated using the new method is not restricted to guanosine, in contrast to 5'-triphosphorylated RNA prepared by in vitro transcription. Therefore, using the new approach, essentially any RNA obtained from solid-phase synthesis or other means can be activated by 5'-adenylation in a practical manner.
Collapse
Affiliation(s)
- Scott K Silverman
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
| |
Collapse
|
32
|
Sutton JM. Charge variants in serum and urine hCG. Clin Chim Acta 2004; 341:199-203. [PMID: 14967177 DOI: 10.1016/j.cccn.2003.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Revised: 12/02/2003] [Accepted: 12/03/2003] [Indexed: 11/16/2022]
Abstract
BACKGROUND All serum and urine pregnancy tests sold in the United States are calibrated against the WHO 3rd and 4th International Standards (3rd and 4th I.S.) of Human Chorionic Gonadotropin (hCG). These standards have been isolated from pregnancy urine; however, they are used to calibrate, and generate antibodies used in both urine and serum hCG tests. hCG molecules may vary in sialic acid content; this changes the acidity of the molecule. Published studies have shown that these carbohydrate elements may alter recognition of hCG in different serum and urine hCG tests. We investigated the charge variants of hCG in serum and urine samples, and in hCG standards. METHODS Samples were analyzed by preparative isoelectric focusing. Charge variants of hCG were quantitated using the DPC Immulite hCG assay. RESULTS A difference was observed in the proportion of charge variants in urine and serum samples. There was a significantly higher proportion of more-acidic variants in the urine samples. CONCLUSIONS Urine-derived standards may not be representative of serum hCG and therefore may not be appropriate for calibrating serum assays. Variation among hCG test results when using different immunoassays has been a persistent problem for years. Additional studies are needed to focus on the molecular dissimilarity of urine and serum hCG, as well as other factors, to determine their significance and contribution to the problem of interassay variation when comparing hCG results.
Collapse
Affiliation(s)
- Jaime M Sutton
- Department of Biochemistry, M.S.C. 10 5580, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA.
| |
Collapse
|
33
|
Caricchio R, McPhie L, Cohen PL. Ultraviolet B radiation-induced cell death: critical role of ultraviolet dose in inflammation and lupus autoantigen redistribution. THE JOURNAL OF IMMUNOLOGY 2004; 171:5778-86. [PMID: 14634086 DOI: 10.4049/jimmunol.171.11.5778] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The nuclear self-Ags targeted in systemic lupus erythematosus translocate to the cell membrane of UV-irradiated apoptotic keratinocytes and may represent an important source of self-immunization. It is hard to understand how the noninflammatory milieu accompanying most apoptosis might provoke an immunogenic response leading to autoantibodies. We have found that the precise amount of keratinocyte UV exposure is crucial in determining the rate of apoptosis, the amount of inflammatory cytokine production, and the degree of autoantigen translocation. Low doses of UVB (</=15 mJ/cm(2)) promptly induced a normal, caspase-dependent apoptosis, while intermediate doses of UV-B (35 mJ/cm(2)) caused apoptosis with altered morphology, slower DNA fragmentation, and poly(ADP-ribose) polymerase degradation accompanied by increased Bcl-2. High doses of UVB (80 mJ/cm(2)) induced instead necrosis. We observed IL-1 production upon intermediate and high UVB doses. Nuclear Ag redistribution was also markedly UV dose dependent: at low doses, Sm, Ku, and DNA translocated to the surfaces of early apoptotic cells. At intermediate doses, these Ags concentrated on the cell membrane when the nucleus was still visible. At high doses, these autoantigens diffused into the cytoplasm and were released into the supernatant. Taken together, the results show that low-dose UVB induces prompt noninflammatory apoptosis. In contrast, intermediate and high doses of UVB induce proinflammatory apoptosis and necrosis, where the production of inflammatory cytokines is accompanied by exposure and release of autoantigens. The key importance of the UV dose on the fate of apoptotic keratinocytes and on their potential immunogenicity should help clarify the role of UVB in inducing systemic lupus erythematosus autoimmunity.
Collapse
Affiliation(s)
- Roberto Caricchio
- Department of Medicine, Division of Rheumatology, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | | | | |
Collapse
|
34
|
Bustillo M. Unsuccessful oocyte retrieval: technical artefact or genuine 'empty follicle syndrome'? Reprod Biomed Online 2004; 8:59-67. [PMID: 14759289 DOI: 10.1016/s1472-6483(10)60498-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Unsuccessful oocyte retrieval after apparently successful ovarian stimulation (also referred to as 'empty follicle syndrome') occurs in 1-7% of women undergoing assisted reproductive techniques. A literature review was performed, as individual studies have reached differing conclusions on the aetiology and treatment or management of the phenomenon. The aetiology is not clear, but probably multifactorial, and occurs in natural and stimulated cycles. In many cases, technical problems such as errors in human chorionic gonadotrophin (HCG) administration or defects in HCG batches can be identified, but this is not sufficient to account for all reported cases. The term empty follicle syndrome is inappropriate in cases in which such procedural factors can be identified. In many patients, however, unsuccessful oocyte retrieval appears to be due to an underlying ovarian dysfunction, and some may have a genuine empty follicle syndrome. Appropriate measures, such as monitoring of serum beta-HCG, should be taken to minimize the risk of unsuccessful oocyte retrieval. This review discusses the potential causes of unsuccessful oocyte retrieval, its clinical implications, and potential solutions to this clinical problem.
Collapse
Affiliation(s)
- María Bustillo
- South Florida Institute for Reproductive Medicine, 7300 SW 62nd Place, 4th Floor, Miami, Florida, USA.
| |
Collapse
|
35
|
Fernández-Miragall O, Martínez-Salas E. Structural organization of a viral IRES depends on the integrity of the GNRA motif. RNA (NEW YORK, N.Y.) 2003; 9:1333-44. [PMID: 14561883 PMCID: PMC1287055 DOI: 10.1261/rna.5950603] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Little is known about the tertiary structure of internal ribosome entry site (IRES) elements. The central domain of foot-and-mouth disease (FMDV) IRES, named 3 or I, contains a conserved GNRA motif, essential for IRES activity. We have combined functional analysis with RNA probing to define its structural organization. We have found that a UNCG motif does not functionally substitute the GNRA motif; moreover, binding of synthetic GNRA stem-loops to domain 3 was significantly reduced in RNAs bearing UCCG or GUAG substitutions. The apical region of domain 3 consists of a four-way junction where residues of the GNRA tetraloop are responsible for the organization of the adjacent stem-loops, as deduced from ribonucleases and dimethyl sulfate accessibility. A single A-to-G substitution in the fourth position of this motif led to a strong RNA reorganization, affecting several nucleotides away in the secondary structure of domain 3. The study of mutants bearing UNCG or GUAG tetraloops revealed lack of protection to chemical attack in native RNA at specific nucleotides relative to the parental GUAA, suggesting that the GNRA motif dictates the organization and stability of domain 3. This effect is likely mediated by the interaction with distant residues. Therefore, the GNRA motif plays a crucial role in the organization of IRES structure with important consequences on activity.
Collapse
Affiliation(s)
- Olga Fernández-Miragall
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas--Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid, Spain
| | | |
Collapse
|
36
|
Fralish GB, Narayan P, Puett D. Consequences of single-chain translation on the structures of two chorionic gonadotropin yoked analogs in alpha-beta and beta-alpha configurations. Mol Endocrinol 2003; 17:757-67. [PMID: 12554764 DOI: 10.1210/me.2002-0317] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Human chorionic gonadotropin (hCG) is a placental-derived heterodimeric glycoprotein hormone, which, through the binding and activation of the LH receptor, rescues the corpus luteum and maintains pregnancy. The three-dimensional structure of hCG is known; however, the relevance of its fold to bioactivity is unclear. Although both subunits (alpha and beta) are required for activity, recent data with single-chain analogs have suggested a diminished role for the cystine knot and an intact heterodimeric interface in binding and receptor activation in vitro. Herein, we report the purification and structural characterization of two yoked (Y) hCG analogs, YhCG1 (beta-alpha) and YhCG3 (alpha-beta). The fusion proteins yielded higher IC50s and EC50s than those of hCG; the maximal hCG-mediated cAMP production, however, was the same. Circular dichroic spectroscopy revealed that the three proteins exhibit distinct far UV circular dichroic spectra, with YhCG1 containing somewhat more secondary structure than YhCG3 and hCG. Limited proteolysis with proteinase K indicated that heterodimeric hCG was much more resistant to cleavage than the single-chain analogs. YhCG1 was more susceptible to proteolysis than YhCG3, and the fragmentation patterns were different in the two proteins. Taken together, the data presented herein provide direct structural evidence for altered three-dimensional conformations in the two single-chain hCG analogs. Thus, the cognate G protein-coupled receptor can recognize and functionally respond to multiple ligand conformations.
Collapse
Affiliation(s)
- Gregory B Fralish
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229, USA
| | | | | |
Collapse
|
37
|
Birken S, Berger P, Bidart JM, Weber M, Bristow A, Norman R, Sturgeon C, Stenman UH. Preparation and characterization of new WHO reference reagents for human chorionic gonadotropin and metabolites. Clin Chem 2003; 49:144-54. [PMID: 12507971 DOI: 10.1373/49.1.144] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The currently used standards for human chorionic gonadotropin (hCG) and its alpha and beta subunits (hCGalpha and hCGbeta) contain substantial amounts of contaminating variants of hCG and other impurities. Furthermore, some partially degraded forms of hCG and its subunits have become of potential clinical importance, e.g., "nicked" forms of hCG (hCGn) and hCGbeta (hCGbetan), which contain cuts in the peptide backbone between amino acids 44-45 or 47-48 in hCGbeta, and a fragment of hCGbeta (hCGbetacf) consisting of amino acids 6-40 and 55-92 bound together by disulfide bridges. The IFCC appointed a working group with the aim of preparing new standards for hCG and related substances to improve standardization of their immunoassays. METHODS Large amounts of hCG and its subunits as well as of hCGn, hCGbetan, and hCGbetacf were prepared by previously developed purification methods in combination with hydrophobic interaction chromatography and reversed-phase HPLC. Each preparation was characterized on the basis of amino acid and sequence analyses, carbohydrate composition, and electrophoretic patterns. Immunoassays for relevant contaminating proteins were also performed. RESULTS The major preparations were homogeneous and free of contaminating proteins. Concentrations of the final preparations were determined by amino acid analysis. CONCLUSIONS Calibrated in substance concentrations (mol/L) based on amino acid analyses, these preparations will facilitate improved standardization of immunoassays for hCG and its metabolites. The six preparations have now been established by the WHO as new 1st Reference Reagents for immunoassays with the following codes: hCG 99/688, hCGbeta 99/650, hCGalpha 99/720, hCGn 99/642, hCGbetan 99/692, and hCGbetacf 99/708. In contrast to the 3rd International Standard (75/537), the clinically most important Reference Reagent for hCG (99/688) contains no hCGn and negligible amounts of free subunits.
Collapse
Affiliation(s)
- Steven Birken
- College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Abstract
BACKGROUND In clinical chemistry, traceability of measurements is of high priority. METHODS In this literature review, current recommendations on the process of establishing traceability (or standardization) are critically discussed. RESULTS Traceability is to be established to the highest international standards by a comprehensive reference measurement system. Elementary to this system are a metrological basis, a measurement unit system, i.e., the Système International d'Unités (SI), its embodiment by a material standard and a calibration hierarchy for transfer of accuracy/trueness to the manufacturer's product calibrators and routine methods. However, for analytes lacking an unequivocally recognized entity, the International Unit (IU) and International Standard (IS) concept have been developed. On this basis, the review distinguishes between traceability of SI- and IU-analytes. CONCLUSIONS SI-traceability, exemplified by cortisol, is straightforward. However, special attention is needed for "free analytes" and "analyte families". For traceability of IU-analytes, exemplified by hCG, the standardization process passes different phases in function of the history of the analyte (discovery, ISs, measurement by bioassays/immunoassays, complete structure elucidation). However, perspectives to the development of an SI-based reference measurement system are realistic. Last but not least, for successful global implementation of the standardization process, consensus of all major players in the field will be required.
Collapse
Affiliation(s)
- Linda M Thienpont
- Laboratorium voor Analytische Chemie. Fac. Farmaceutische Wetenschappen, Universiteit Gent, Harelbekestraat 72, B-9000, Ghent, Belgium.
| | | | | |
Collapse
|
39
|
Kovalevskaya G, Genbacev O, Fisher SJ, Caceres E, O'Connor JF. Trophoblast origin of hCG isoforms: cytotrophoblasts are the primary source of choriocarcinoma-like hCG. Mol Cell Endocrinol 2002; 194:147-55. [PMID: 12242037 DOI: 10.1016/s0303-7207(02)00135-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have previously demonstrated that a hyperglycosylated isoform of chorionic gonadotropin (hCG) (B152 hCG) is detected in the blood and urine in early pregnancy and is subsequently rapidly replaced by the hCG isoform (B109 hCG) characteristic of later pregnancy. In the current study we have extended our work on the origin of these isoforms. We have used a combination of in situ and in vitro approaches. Localization studies in placental tissues showed that monoclonal antibody B109 stained very specifically syncytiotrophoblast (STBs) from first and second trimester tissues. At term, STBs exhibited no B109 staining at all. Immunostaining with B152 antibody, that recognize the hyperglycosylated isoform of hCG, revealed only punctate staining of STBs in most villi of first trimester tissue. Both antibodies B109 and B152 failed to stain cytotrophoblasts (CTBs). To assess the functional relevance of these observations we analyzed conditioned media from purified CTBs using two immunometric assays, one of which (B152-B207*) has primary specificity for the hyperglycosylated, choriocarcinoma-like hCG and the other (B109-B108*) having primary specificity for the later pregnancy hCG isoform. Regardless of gestational age, isolated CTBs secreted predominantly B152 hCG isoform in contrast to placental villi (predominantly STBs), which released primarily the B109 hCG isoform. Isolated CTBs, however, failed to immunostain with both B109 and B152 antibodies. To resolve this contradiction, we cultured CTBs in the presence of brefeldin A, a drug known to block secretion by inhibiting protein translocation from the endoplasmic reticulum to the Golgi vesicles. Brefeldin A treated CTBs stained strongly with B109 and did not stain or stained weakly with B152 antibody. We assume that treatment with brefeldin A impaired glycosylation of beta subunit and consequently inhibited the production of hyperglycosylated form of hCG recognized by B152. In summary, our in vitro experiments indicate that both isoforms of hCG are produced by villus CTBs and that the dominant isoform is the one recognized by antibody B152. STBs produce primarily the less glycosylated B109 hCG isoform. This data suggests that at the beginning of pregnancy villus CTBs are the major source of the B152 hCG isoform. This finding is supported by our clinical data that show that the dominant hCG isoform in the blood and urine of pregnant women in the first 6 weeks of pregnancy is recognized by B152 (). The inversion of the B152/B109 ratio observed after 6-7 weeks of pregnancy can be explained by the reduction of number of villus CTBs and/or by maturation of STBs.
Collapse
Affiliation(s)
- G Kovalevskaya
- Irving Center for Clinical Research, Columbia University College of Physicians and Surgeons, 630 W 168th Street, New York, NY 10032, USA
| | | | | | | | | |
Collapse
|
40
|
Abstract
Genomics and proteomics are playing increasingly important roles as discovery tools in basic biological sciences and as diagnostic and rational therapeutic aids in the clinical arena. In recent years, high-density arrays of specified DNA sequences have gained popularity. Protein microarrays are at the forefront of this biochip revolution and promise the parallel examination of large numbers of proteins. These miniaturized arrays are currently being developed to facilitate high analytical resolution, detection sensitivity and sample throughput. Many challenges are presented by proteome scale manipulation of proteins, as there is currently no methodological equivalent to the gene chip for comparative proteomics.
Collapse
Affiliation(s)
- Anupam Talapatra
- Department of Vascular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | |
Collapse
|
41
|
Arturi F, Lacroix L, Presta I, Scarpelli D, Caillou B, Schlumberger M, Russo D, Bidart JM, Filetti S. Regulation by human chorionic gonadotropin of sodium/iodide symporter gene expression in the JAr human choriocarcinoma cell line. Endocrinology 2002; 143:2216-20. [PMID: 12021185 DOI: 10.1210/endo.143.6.8844] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Sodium/iodide symporter (NIS) gene and protein expressions have been recently described in human cytotrophoblasts, emphasizing its potential function in the active transport of iodide from the mother to the fetus. In this study we analyzed NIS expression and function in the human JAr placental choriocarcinoma cell line. Using real-time quantitative RT-PCR, we first demonstrated that NIS transcripts are expressed at a high level in JAr cells compared with other cell lines, including thyroid cancer cells. Functional analysis clearly showed that Jar cells are able to concentrate iodide in presence of hCG. Iodide accumulation increased after 2-h exposure to 5 IU/ml hCG, to 6-fold over the basal level after 8 h. This effect was reproduced using forskolin, the cAMP analog (Bu)(2)-cAMP, and phorbol acetate. Moreover, hCG increased both NIS mRNA after 2 h and NIS protein levels after 4 h, reaching a maximum after 8 h in both cases. In conclusion, our data demonstrate that 1) NIS is expressed in JAr cells; 2) iodide transport in JAr cells is regulated by hCG and by cAMP-dependent and -independent mechanisms; 3) the stimulation of iodide uptake is due to an increase in both NIS mRNA and protein levels; and 4) JAr cells may represent an excellent in vitro model suitable to analyze the molecular mechanisms involved in iodide transport from mother to fetus.
Collapse
Affiliation(s)
- Franco Arturi
- Dipartimento di Medicina Sperimentale e Clinica, Università di Catanzaro, Magna Graecia 88100 Catanzaro, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Jansen R, Greenbaum D, Gerstein M. Relating whole-genome expression data with protein-protein interactions. Genome Res 2002; 12:37-46. [PMID: 11779829 PMCID: PMC155252 DOI: 10.1101/gr.205602] [Citation(s) in RCA: 449] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We investigate the relationship of protein-protein interactions with mRNA expression levels, by integrating a variety of data sources for yeast. We focus on known protein complexes that have clearly defined interactions between their subunits. We find that subunits of the same protein complex show significant coexpression, both in terms of similarities of absolute mRNA levels and expression profiles, e.g., we can often see subunits of a complex having correlated patterns of expression over a time course. We classify the yeast protein complexes as either permanent or transient, with permanent ones being maintained through most cellular conditions. We find that, generally, permanent complexes, such as the ribosome and proteasome, have a particularly strong relationship with expression, while transient ones do not. However, we note that several transient complexes, such as the RNA polymerase II holoenzyme and the replication complex, can be subdivided into smaller permanent ones, which do have a strong relationship to gene expression. We also investigated the interactions in aggregated, genome-wide data sets, such as the comprehensive yeast two-hybrid experiments, and found them to have only a weak relationship with gene expression, similar to that of transient complexes. (Further details on genecensus.org/expression/interactions and bioinfo.mbb.yale.edu/expression/interactions.)
Collapse
Affiliation(s)
- Ronald Jansen
- Department of Molecular Biophysics, Yale University, New Haven, Connecticut 06520, USA
| | | | | |
Collapse
|
43
|
Birken S, Kovalevskaya G, O'Connor J. Immunochemical measurement of early pregnancy isoforms of HCG: potential applications to fertility research, prenatal diagnosis, and cancer. Arch Med Res 2001; 32:635-43. [PMID: 11750741 DOI: 10.1016/s0188-4409(01)00329-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Human chorionic gonadotropin, the glycoprotein hormone of pregnancy, is found naturally in blood and urine in a variety of isoforms. These variants are related to both peptide bond cleavages (such as the nicked forms of hCG) and the beta core fragment urinary metabolite, as well as the larger variety of species resulting from carbohydrate heterogeneity. We have recently developed immunoassay systems that can measure nicked forms of hCG (antibody B151) as well as particular high carbohydrate variants (hyperglycosylated forms) of hCG (B152), which are associated with cancers producing hCG. Using the assay system for nicked hCG, we found that nicked hCG does not appear to be present as a significant hCG isoform during normal pregnancies if the urine specimens are well preserved. Applying the assay for hyperglycosylated hCG isoforms, we discovered that these forms are prevalent during very early pregnancy and decline rapidly to low concentration after the first 6 weeks of pregnancy. Persistence of these early pregnancy forms does not bode well for the pregnancy. Other investigators report that measurement of such hCG isoforms may aid in diagnosis of Down syndrome pregnancies. In summary, measurement of the hyperglycosylated hCG isoforms are useful for evaluation of healthy progress of normal pregnancy, as an additional detection marker for Down syndrome pregnancies, and as a potential new marker of trophoblastic malignancy. New reference preparations will soon be available for the calibration of assay systems for measurement of many of these hCG variants and metabolites.
Collapse
Affiliation(s)
- S Birken
- Department of Obstetrics and Gynecology and the Irving Center for Clinical Research, Columbia College of Physicians & Surgeons, New York, NY 10032, USA.
| | | | | |
Collapse
|