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Manjunath LE, Singh A, Sahoo S, Mishra A, Padmarajan J, Basavaraju CG, Eswarappa SM. Stop codon read-through of mammalian MTCH2 leading to an unstable isoform regulates mitochondrial membrane potential. J Biol Chem 2020; 295:17009-17026. [PMID: 33028634 PMCID: PMC7863902 DOI: 10.1074/jbc.ra120.014253] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 10/02/2020] [Indexed: 12/13/2022] Open
Abstract
Stop codon read-through (SCR) is a process of continuation of translation beyond a stop codon. This phenomenon, which occurs only in certain mRNAs under specific conditions, leads to a longer isoform with properties different from that of the canonical isoform. MTCH2, which encodes a mitochondrial protein that regulates mitochondrial metabolism, was selected as a potential read-through candidate based on evolutionary conservation observed in the proximal region of its 3' UTR. Here, we demonstrate translational read-through across two evolutionarily conserved, in-frame stop codons of MTCH2 using luminescence- and fluorescence-based assays, and by analyzing ribosome-profiling and mass spectrometry (MS) data. This phenomenon generates two isoforms, MTCH2x and MTCH2xx (single- and double-SCR products, respectively), in addition to the canonical isoform MTCH2, from the same mRNA. Our experiments revealed that a cis-acting 12-nucleotide sequence in the proximal 3' UTR of MTCH2 is the necessary signal for SCR. Functional characterization showed that MTCH2 and MTCH2x were localized to mitochondria with a long t1/2 (>36 h). However, MTCH2xx was found predominantly in the cytoplasm. This mislocalization and its unique C terminus led to increased degradation, as shown by greatly reduced t1/2 (<1 h). MTCH2 read-through-deficient cells, generated using CRISPR-Cas9, showed increased MTCH2 expression and, consistent with this, decreased mitochondrial membrane potential. Thus, double-SCR of MTCH2 regulates its own expression levels contributing toward the maintenance of normal mitochondrial membrane potential.
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Affiliation(s)
- Lekha E Manjunath
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Anumeha Singh
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Sarthak Sahoo
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Ashutosh Mishra
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Jinsha Padmarajan
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | | | - Sandeep M Eswarappa
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India.
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52
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Minati R, Perreault C, Thibault P. A Roadmap Toward the Definition of Actionable Tumor-Specific Antigens. Front Immunol 2020; 11:583287. [PMID: 33424836 PMCID: PMC7793940 DOI: 10.3389/fimmu.2020.583287] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/30/2020] [Indexed: 12/15/2022] Open
Abstract
The search for tumor-specific antigens (TSAs) has considerably accelerated during the past decade due to the improvement of proteogenomic detection methods. This provides new opportunities for the development of novel antitumoral immunotherapies to mount an efficient T cell response against one or multiple types of tumors. While the identification of mutated antigens originating from coding exons has provided relatively few TSA candidates, the possibility of enlarging the repertoire of targetable TSAs by looking at antigens arising from non-canonical open reading frames opens up interesting avenues for cancer immunotherapy. In this review, we outline the potential sources of TSAs and the mechanisms responsible for their expression strictly in cancer cells. In line with the heterogeneity of cancer, we propose that discrete families of TSAs may be enriched in specific cancer types.
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Affiliation(s)
- Robin Minati
- École Normale Supérieure de Lyon, Université Claude Bernard Lyon I, Université de Lyon, Lyon, France
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Claude Perreault
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Department of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Pierre Thibault
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Department of Chemistry, Université de Montréal, Montréal, QC, Canada
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53
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Borst P. The malate-aspartate shuttle (Borst cycle): How it started and developed into a major metabolic pathway. IUBMB Life 2020; 72:2241-2259. [PMID: 32916028 PMCID: PMC7693074 DOI: 10.1002/iub.2367] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022]
Abstract
This article presents a personal and critical review of the history of the malate-aspartate shuttle (MAS), starting in 1962 and ending in 2020. The MAS was initially proposed as a route for the oxidation of cytosolic NADH by the mitochondria in Ehrlich ascites cell tumor lacking other routes, and to explain the need for a mitochondrial aspartate aminotransferase (glutamate oxaloacetate transaminase 2 [GOT2]). The MAS was soon adopted in the field as a major pathway for NADH oxidation in mammalian tissues, such as liver and heart, even though the energetics of the MAS remained a mystery. Only in the 1970s, LaNoue and coworkers discovered that the efflux of aspartate from mitochondria, an essential step in the MAS, is dependent on the proton-motive force generated by the respiratory chain: for every aspartate effluxed, mitochondria take up one glutamate and one proton. This makes the MAS in practice uni-directional toward oxidation of cytosolic NADH, and explains why the free NADH/NAD ratio is much higher in the mitochondria than in the cytosol. The MAS is still a very active field of research. Most recently, the focus has been on the role of the MAS in tumors, on cells with defects in mitochondria and on inborn errors in the MAS. The year 2019 saw the discovery of two new inborn errors in the MAS, deficiencies in malate dehydrogenase 1 and in aspartate transaminase 2 (GOT2). This illustrates the vitality of ongoing MAS research.
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Affiliation(s)
- Piet Borst
- Division of Cell BiologyThe Netherlands Cancer InstituteAmsterdamThe Netherlands
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54
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Palma M, Lejeune F. Deciphering the molecular mechanism of stop codon readthrough. Biol Rev Camb Philos Soc 2020; 96:310-329. [PMID: 33089614 DOI: 10.1111/brv.12657] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 09/23/2020] [Accepted: 09/26/2020] [Indexed: 12/11/2022]
Abstract
Recognition of the stop codon by the translation machinery is essential to terminating translation at the right position and to synthesizing a protein of the correct size. Under certain conditions, the stop codon can be recognized as a coding codon promoting translation, which then terminates at a later stop codon. This event, called stop codon readthrough, occurs either by error, due to a dedicated regulatory environment leading to generation of different protein isoforms, or through the action of a readthrough compound. This review focuses on the mechanisms of stop codon readthrough, the nucleotide and protein environments that facilitate or inhibit it, and the therapeutic interest of stop codon readthrough in the treatment of genetic diseases caused by nonsense mutations.
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Affiliation(s)
- Martine Palma
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, UMR9020 - U1277 - CANTHER - Cancer Heterogeneity Plasticity and Resistance to Therapies, F-59000 Lille, France
| | - Fabrice Lejeune
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, UMR9020 - U1277 - CANTHER - Cancer Heterogeneity Plasticity and Resistance to Therapies, F-59000 Lille, France
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55
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Ma Y, Li Y, Zhang H, Wang Y, Wu C, Huang W. Malvidin induces hepatic stellate cell apoptosis via the endoplasmic reticulum stress pathway and mitochondrial pathway. Food Sci Nutr 2020; 8:5095-5106. [PMID: 32994970 PMCID: PMC7500790 DOI: 10.1002/fsn3.1810] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/26/2020] [Accepted: 07/19/2020] [Indexed: 12/18/2022] Open
Abstract
Blueberries have great beneficial effects due to high level of anthocyanins, especially malvidin. Hepatic stellate cells (HSCs) can be activated and increase excessive extracellular matrix (ECM) components, which play a central role in liver fibrogenesis. Therefore, activated HSC's apoptosis can be induced to recover liver fibrosis. Malvidin's effects on apoptosis in rat activated hepatic stellate T6 cells (HSC-T6) in vitro were investigated here. High concentration of malvidin was found to significantly induce apoptosis, activate caspase-3, increase malondialdehyde, upregulate Bax, but downregulate Bcl-2. Moreover, malvidin upregulated the protein levels of some endoplasmic reticulum stress (ERS)-typical markers, including caspase-12, glucose-regulated protein 78 (GRP78), and CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), suggesting that malvidin induced HSC apoptosis by the ERS apoptosis pathway as well as the mitochondrial-dependent pathway. These findings indicated that blueberry anthocyanins, especially malvidin, could induce activated hepatic stellate cell apoptosis and might act as one kind of functional food ingredient or a novel nutraceutical beneficial for liver health.
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Affiliation(s)
- Yanhong Ma
- Institute of Agro‐Product ProcessingJiangsu Academy of Agricultural SciencesNanjingChina
- School of Food and Biological EngineeringJiangsu UniversityZhenjiangChina
| | - Yahui Li
- Institute of Agro‐Product ProcessingJiangsu Academy of Agricultural SciencesNanjingChina
| | - Hongzhi Zhang
- Institute of Agro‐Product ProcessingJiangsu Academy of Agricultural SciencesNanjingChina
| | - Ying Wang
- Institute of Agro‐Product ProcessingJiangsu Academy of Agricultural SciencesNanjingChina
| | - Caie Wu
- College of Light Industry and Food EngineeringNanjing Forestry UniversityNanjingChina
| | - Wuyang Huang
- Institute of Agro‐Product ProcessingJiangsu Academy of Agricultural SciencesNanjingChina
- School of Food and Biological EngineeringJiangsu UniversityZhenjiangChina
- Jiangsu Key Laboratory for Horticultural Crop Genetic ImprovementJiangsu Academy of Agricultural SciencesNanjingChina
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56
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Metabolic stress promotes stop-codon readthrough and phenotypic heterogeneity. Proc Natl Acad Sci U S A 2020; 117:22167-22172. [PMID: 32839318 DOI: 10.1073/pnas.2013543117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Accurate protein synthesis is a tightly controlled biological process with multiple quality control steps safeguarded by aminoacyl-transfer RNA (tRNA) synthetases and the ribosome. Reduced translational accuracy leads to various physiological changes in both prokaryotes and eukaryotes. Termination of translation is signaled by stop codons and catalyzed by release factors. Occasionally, stop codons can be suppressed by near-cognate aminoacyl-tRNAs, resulting in protein variants with extended C termini. We have recently shown that stop-codon readthrough is heterogeneous among single bacterial cells. However, little is known about how environmental factors affect the level and heterogeneity of stop-codon readthrough. In this study, we have combined dual-fluorescence reporters, mass spectrometry, mathematical modeling, and single-cell approaches to demonstrate that a metabolic stress caused by excess carbon substantially increases both the level and heterogeneity of stop-codon readthrough. Excess carbon leads to accumulation of acid metabolites, which lower the pH and the activity of release factors to promote readthrough. Furthermore, our time-lapse microscopy experiments show that single cells with high readthrough levels are more adapted to severe acid stress conditions and are more sensitive to an aminoglycoside antibiotic. Our work thus reveals a metabolic stress that promotes translational heterogeneity and phenotypic diversity.
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57
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Abstract
Peroxisomes are metabolic organelles involved in lipid metabolism and cellular redox balance. Peroxisomal function is central to fatty acid oxidation, ether phospholipid synthesis, bile acid synthesis, and reactive oxygen species homeostasis. Human disorders caused by genetic mutations in peroxisome genes have led to extensive studies on peroxisome biology. Peroxisomal defects are linked to metabolic dysregulation in diverse human diseases, such as neurodegeneration and age-related disorders, revealing the significance of peroxisome metabolism in human health. Cancer is a disease with metabolic aberrations. Despite the critical role of peroxisomes in cell metabolism, the functional effects of peroxisomes in cancer are not as well recognized as those of other metabolic organelles, such as mitochondria. In addition, the significance of peroxisomes in cancer is less appreciated than it is in degenerative diseases. In this review, I summarize the metabolic pathways in peroxisomes and the dysregulation of peroxisome metabolism in cancer. In addition, I discuss the potential of inactivating peroxisomes to target cancer metabolism, which may pave the way for more effective cancer treatment.
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58
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Kramarski L, Arbely E. Translational read-through promotes aggregation and shapes stop codon identity. Nucleic Acids Res 2020; 48:3747-3760. [PMID: 32128584 PMCID: PMC7144920 DOI: 10.1093/nar/gkaa136] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/07/2020] [Accepted: 02/22/2020] [Indexed: 12/14/2022] Open
Abstract
Faithful translation of genetic information depends on the ability of the translational machinery to decode stop codons as termination signals. Although termination of protein synthesis is highly efficient, errors in decoding of stop codons may lead to the synthesis of C-terminally extended proteins. It was found that in eukaryotes such elongated proteins do not accumulate in cells. However, the mechanism for sequestration of C-terminally extended proteins is still unknown. Here we show that 3′-UTR-encoded polypeptides promote aggregation of the C-terminally extended proteins, and targeting to lysosomes. We demonstrate that 3′-UTR-encoded polypeptides can promote different levels of protein aggregation, similar to random sequences. We also show that aggregation of endogenous proteins can be induced by aminoglycoside antibiotics that promote stop codon read-through, by UAG suppressor tRNA, or by knokcdown of release factor 1. Furthermore, we find correlation between the fidelity of termination signals, and the predicted propensity of downstream 3′-UTR-encoded polypeptides to form intrinsically disordered regions. Our data highlight a new quality control mechanism for elimination of C-terminally elongated proteins.
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Affiliation(s)
- Lior Kramarski
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Eyal Arbely
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.,Department of Chemistry and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
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59
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Kremp M, Bittner E, Martorana D, Klingenberger A, Stehlik T, Bölker M, Freitag J. Non-AUG Translation Initiation Generates Peroxisomal Isoforms of 6-Phosphogluconate Dehydrogenase in Fungi. Front Cell Dev Biol 2020; 8:251. [PMID: 32432107 PMCID: PMC7214817 DOI: 10.3389/fcell.2020.00251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 03/25/2020] [Indexed: 11/16/2022] Open
Abstract
Proteins destined for transport to specific organelles usually contain targeting information, which are embedded in their sequence. Many enzymes are required in more than one cellular compartment and different molecular mechanisms are used to achieve dual localization. Here we report a cryptic type 2 peroxisomal targeting signal encoded in the 5′ untranslated region of fungal genes coding for 6-phosphogluconate dehydrogenase (PGD), a key enzyme of the oxidative pentose phosphate pathway. The conservation of the cryptic PTS2 motif suggests a biological function. We observed that translation from a non-AUG start codon generates an N-terminally extended peroxisomal isoform of Ustilago maydis PGD. Non-canonical initiation occurred at the sequence AGG AUU, consisting of two near-cognate start codons in tandem. Taken together, our data reveal non-AUG translation initiation as an additional mechanism to achieve the dual localization of a protein required both in the cytosol and the peroxisomes.
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Affiliation(s)
- Marco Kremp
- Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Elena Bittner
- Department of Biology, Philipps-University Marburg, Marburg, Germany
| | | | | | - Thorsten Stehlik
- Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Michael Bölker
- Department of Biology, Philipps-University Marburg, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, Marburg, Germany
| | - Johannes Freitag
- Department of Biology, Philipps-University Marburg, Marburg, Germany
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60
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Stehlik T, Kremp M, Kahnt J, Bölker M, Freitag J. Peroxisomal targeting of a protein phosphatase type 2C via mitochondrial transit. Nat Commun 2020; 11:2355. [PMID: 32398688 PMCID: PMC7217942 DOI: 10.1038/s41467-020-16146-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 04/16/2020] [Indexed: 11/16/2022] Open
Abstract
Correct intracellular distribution of proteins is critical for the function of eukaryotic cells. Certain proteins are targeted to more than one cellular compartment, e.g. to mitochondria and peroxisomes. The protein phosphatase Ptc5 from Saccharomyces cerevisiae contains an N-terminal mitochondrial presequence followed by a transmembrane domain, and has been detected in the mitochondrial intermembrane space. Here we show mitochondrial transit of Ptc5 to peroxisomes. Translocation of Ptc5 to peroxisomes depended both on the C-terminal peroxisomal targeting signal (PTS1) and N-terminal cleavage by the mitochondrial inner membrane peptidase complex. Indirect targeting of Ptc5 to peroxisomes prevented deleterious effects of its phosphatase activity in the cytosol. Sorting of Ptc5 involves simultaneous interaction with import machineries of both organelles. We identify additional mitochondrial proteins with PTS1, which localize in both organelles and can increase their physical association. Thus, a tug-of-war-like mechanism can influence the interaction and communication of two cellular compartments.
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Affiliation(s)
- Thorsten Stehlik
- Department of Biology, Philipps University Marburg, Marburg, Germany
| | - Marco Kremp
- Department of Biology, Philipps University Marburg, Marburg, Germany
| | - Jörg Kahnt
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Michael Bölker
- Department of Biology, Philipps University Marburg, Marburg, Germany.
- LOEWE Center for Synthetic Microbiology, Marburg, Germany.
| | - Johannes Freitag
- Department of Biology, Philipps University Marburg, Marburg, Germany.
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61
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Kiniry SJ, Michel AM, Baranov PV. Computational methods for ribosome profiling data analysis. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1577. [PMID: 31760685 DOI: 10.1002/wrna.1577] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022]
Abstract
Since the introduction of the ribosome profiling technique in 2009 its popularity has greatly increased. It is widely used for the comprehensive assessment of gene expression and for studying the mechanisms of regulation at the translational level. As the number of ribosome profiling datasets being produced continues to grow, so too does the need for reliable software that can provide answers to the biological questions it can address. This review describes the computational methods and tools that have been developed to analyze ribosome profiling data at the different stages of the process. It starts with initial routine processing of raw data and follows with more specific tasks such as the identification of translated open reading frames, differential gene expression analysis, or evaluation of local or global codon decoding rates. The review pinpoints challenges associated with each step and explains the ways in which they are currently addressed. In addition it provides a comprehensive, albeit incomplete, list of publicly available software applicable to each step, which may be a beneficial starting point to those unexposed to ribosome profiling analysis. The outline of current challenges in ribosome profiling data analysis may inspire computational biologists to search for novel, potentially superior, solutions that will improve and expand the bioinformatician's toolbox for ribosome profiling data analysis. This article is characterized under: Translation > Ribosome Structure/Function RNA Evolution and Genomics > Computational Analyses of RNA Translation > Translation Mechanisms Translation > Translation Regulation.
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Affiliation(s)
- Stephen J Kiniry
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Audrey M Michel
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
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62
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Wu Y, Qiu J, Chen S, Chen X, Zhang J, Zhuang J, Liu S, Yang M, Zhou P, Chen H, Ge J, Yu K, Zhuang J. Crx Is Posttranscriptionally Regulated by Light Stimulation in Postnatal Rat Retina. Front Cell Dev Biol 2020; 8:174. [PMID: 32318566 PMCID: PMC7154164 DOI: 10.3389/fcell.2020.00174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 03/02/2020] [Indexed: 11/13/2022] Open
Abstract
Cone rod homeobox (Crx) plays a key role at the center of a regulatory network that coordinates many pathways in the retina. Its abnormal expression induces retinal disorders. However, the underlying regulatory mechanism of Crx expression is not well defined. Here, we present data that show that the levels of Crx mRNA were inconsistent with that of Crx protein in primary retinal neurocytes cultured in light conditions. Crx protein levels were significantly higher (2.56-fold) in cells cultured in the dark than in cells cultured in light, whereas Crx mRNA was not changed in either type of cell. Moreover, the expression of Crx protein showed a significant light intensity-dependent decrease. Consistently, Crx downstream genes rhodopsin and arrestin also decreased in retinal neurocytes upon light exposure. Furthermore, Crx promoter activity assay performed in primary retinal neurocytes further indicated that light exposure and darkness did not affect its inducibility. In addition, the inconsistency between Crx mRNA and protein expression after light exposure was not observed in 661w cells transfected with plasmid pcDNA3.1-Crx, suggesting that the inconsistency between Crx mRNA and protein induced by light was specific to the endogenous Crx. More importantly, this observation was confirmed in vivo in postnatal day 15 (P15) retinas but not in adult retinas, further implicating that the posttranscriptional regulation mechanism may be involved in Crx expression in the developing retina. Therefore, our study sheds light on the mechanism of Crx expression in postnatal rat retina.
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Affiliation(s)
- Yihui Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jin Qiu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shuilian Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xi Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jing Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jiejie Zhuang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Sian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Meng Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Pan Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Haoting Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jian Ge
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Keming Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jing Zhuang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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63
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Rodnina MV, Korniy N, Klimova M, Karki P, Peng BZ, Senyushkina T, Belardinelli R, Maracci C, Wohlgemuth I, Samatova E, Peske F. Translational recoding: canonical translation mechanisms reinterpreted. Nucleic Acids Res 2020; 48:1056-1067. [PMID: 31511883 PMCID: PMC7026636 DOI: 10.1093/nar/gkz783] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/21/2019] [Accepted: 08/30/2019] [Indexed: 01/15/2023] Open
Abstract
During canonical translation, the ribosome moves along an mRNA from the start to the stop codon in exact steps of one codon at a time. The collinearity of the mRNA and the protein sequence is essential for the quality of the cellular proteome. Spontaneous errors in decoding or translocation are rare and result in a deficient protein. However, dedicated recoding signals in the mRNA can reprogram the ribosome to read the message in alternative ways. This review summarizes the recent advances in understanding the mechanisms of three types of recoding events: stop-codon readthrough, –1 ribosome frameshifting and translational bypassing. Recoding events provide insights into alternative modes of ribosome dynamics that are potentially applicable to other non-canonical modes of prokaryotic and eukaryotic translation.
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Affiliation(s)
- Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Natalia Korniy
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Mariia Klimova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Prajwal Karki
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Bee-Zen Peng
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Tamara Senyushkina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Riccardo Belardinelli
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Cristina Maracci
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Ingo Wohlgemuth
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
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64
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Beznosková P, Pavlíková Z, Zeman J, Echeverría Aitken C, Valášek LS. Yeast applied readthrough inducing system (YARIS): an invivo assay for the comprehensive study of translational readthrough. Nucleic Acids Res 2020; 47:6339-6350. [PMID: 31069379 PMCID: PMC6614816 DOI: 10.1093/nar/gkz346] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/17/2019] [Accepted: 04/25/2019] [Indexed: 01/24/2023] Open
Abstract
Stop codon readthrough—the decoding of a stop codon by a near-cognate tRNA—is employed by viruses to balance levels of enzymatic and structural proteins and by eukaryotic cells to enable isoform-specific protein synthesis in response to external stimuli. Owing to the prevalence of premature termination codons in human disease, readthrough has emerged as an attractive therapeutic target. A growing list of various features, for example the +4 nucleotide immediately following the stop codon, modulate readthrough levels, underscoring the need for systematic investigation of readthrough. Here, we identified and described a complete group of yeast tRNAs that induce readthrough in the stop-codon tetranucleotide manner when overexpressed, designated readthrough-inducing tRNAs (rti-tRNAs). These rti-tRNAs are the keystones of YARIS (yeast applied readthrough inducing system), a reporter-based assay enabling simultaneous detection of readthrough levels at all twelve stop-codon tetranucleotides and as a function of the complete set of rti-tRNAs. We demonstrate the utility of YARIS for systematic study of translation readthrough by employing it to interrogate the effects of natural rti-tRNA modifications, as well as various readthrough-inducing drugs (RTIDs). This analysis identified a variety of genetic interactions demonstrating the power of YARIS to characterize existing and identify novel RTIDs.
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Affiliation(s)
- Petra Beznosková
- Laboratory of Regulation of Gene Expression, Institute of Microbiology ASCR, Videnska 1083, 142 20 Prague, the Czech Republic
| | - Zuzana Pavlíková
- Laboratory of Regulation of Gene Expression, Institute of Microbiology ASCR, Videnska 1083, 142 20 Prague, the Czech Republic
| | - Jakub Zeman
- Laboratory of Regulation of Gene Expression, Institute of Microbiology ASCR, Videnska 1083, 142 20 Prague, the Czech Republic
| | - Colin Echeverría Aitken
- Biology Department and Biochemistry Program, Vassar College, 124 Raymond Avenue, Poughkeepsie 12601, NY, USA
| | - Leoš S Valášek
- Laboratory of Regulation of Gene Expression, Institute of Microbiology ASCR, Videnska 1083, 142 20 Prague, the Czech Republic
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Palazzo C, Abbrescia P, Valente O, Nicchia GP, Banitalebi S, Amiry-Moghaddam M, Trojano M, Frigeri A. Tissue Distribution of the Readthrough Isoform of AQP4 Reveals a Dual Role of AQP4ex Limited to CNS. Int J Mol Sci 2020; 21:ijms21041531. [PMID: 32102323 PMCID: PMC7073200 DOI: 10.3390/ijms21041531] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/14/2020] [Accepted: 02/19/2020] [Indexed: 02/06/2023] Open
Abstract
Translational readthrough (TRT) of aquaporin-4 (AQP4) has remarkably expanded the importance of this new post-transcriptional mechanism, as well as the regulation potential of AQP4. The TRT isoform of AQP4, named AQP4ex, is central for both AQP4 polarization and water channel activity in the central nervous system (CNS). Here we evaluate the relevance of the TRT mechanism by analyzing whether AQP4ex is also expressed in peripheral tissues and whether the expression of AQP4ex is necessary for its polarized expression as it occurs in perivascular astrocyte processes. To this purpose, AQP4ex null mice were used, and analysis was performed by immunolocalization and immunoblot. The results demonstrate that AQP4ex is expressed in kidney, stomach, trachea and skeletal muscle with the same localization pattern as the canonical AQP4 isoforms. AQP4ex protein levels vary from 6% to about 13% of the total AQP4 protein levels in peripheral tissues. Immunogold electron microscopy experiments demonstrated the localization of AQP4ex at the astrocytic endfeet, and experiments conducted on AQP4ex null mice CNS confirmed that the expression of AQP4ex is necessary for anchoring of the perivascular AQP4. Without the readthrough isoform, AQP4 assemblies are mis-localized, being uniformly distributed on the astrocyte processes facing the neuropile. No alteration of AQP4 polarization was found in AQP4ex null kidney, stomach, trachea or skeletal muscle, suggesting that AQP4ex does not have a role for proper membrane localization of AQP4 in peripheral tissues. We conclude that a dual role for AQP4ex is limited to the CNS.
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Affiliation(s)
- Claudia Palazzo
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Pasqua Abbrescia
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Onofrio Valente
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy;
| | - Shervin Banitalebi
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (S.B.); (M.A.-M.)
| | - Mahmood Amiry-Moghaddam
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (S.B.); (M.A.-M.)
| | - Maria Trojano
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Antonio Frigeri
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
- Correspondence:
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Wangen JR, Green R. Stop codon context influences genome-wide stimulation of termination codon readthrough by aminoglycosides. eLife 2020; 9:52611. [PMID: 31971508 PMCID: PMC7089771 DOI: 10.7554/elife.52611] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 01/22/2020] [Indexed: 12/14/2022] Open
Abstract
Stop codon readthrough (SCR) occurs when the ribosome miscodes at a stop codon. Such readthrough events can be therapeutically desirable when a premature termination codon (PTC) is found in a critical gene. To study SCR in vivo in a genome-wide manner, we treated mammalian cells with aminoglycosides and performed ribosome profiling. We find that in addition to stimulating readthrough of PTCs, aminoglycosides stimulate readthrough of normal termination codons (NTCs) genome-wide. Stop codon identity, the nucleotide following the stop codon, and the surrounding mRNA sequence context all influence the likelihood of SCR. In comparison to NTCs, downstream stop codons in 3′UTRs are recognized less efficiently by ribosomes, suggesting that targeting of critical stop codons for readthrough may be achievable without general disruption of translation termination. Finally, we find that G418-induced miscoding alters gene expression with substantial effects on translation of histone genes, selenoprotein genes, and S-adenosylmethionine decarboxylase (AMD1). Many genes provide a set of instructions needed to build a protein, which are read by structures called ribosomes through a process called translation. The genetic information contains a short, coded instruction called a stop codon which marks the end of the protein. When a ribosome finds a stop codon it should stop building and release the protein it has made. Ribosomes do not always stop at stop codons. Certain chemicals can actually prevent ribosomes from detecting stop codons correctly, and aminoglycosides are drugs that have exactly this effect. Aminoglycosides can be used as antibiotics at low doses because they interfere with ribosomes in bacteria, but at higher doses they can also prevent ribosomes from detecting stop codons in human cells. When ribosomes do not stop at a stop codon this is called readthrough. There are different types of stop codons and some are naturally more effective at stopping ribosomes than others. Wangen and Green have now examined the effect of an aminoglycoside called G418 on ribosomes in human cells grown in the laboratory. The results showed how ribosomes interacted with genetic information and revealed that certain stop codons are more affected by G418 than others. The stop codon and other genetic sequences around it affect the likelihood of readthrough. Wangen and Green also showed that sequences that encourage translation to stop are more common in the area around stop codons. These findings highlight an evolutionary pressure driving more genes to develop strong stop codons that resist readthrough. Despite this, some are still more affected by drugs like G418 than others. Some genetic conditions, like cystic fibrosis, result from incorrect stop codons in genes. Drugs that promote readthrough specifically in these genes could be useful new treatments.
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Affiliation(s)
- Jamie R Wangen
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Rachel Green
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
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Wanders RJA, Vaz FM, Waterham HR, Ferdinandusse S. Fatty Acid Oxidation in Peroxisomes: Enzymology, Metabolic Crosstalk with Other Organelles and Peroxisomal Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1299:55-70. [PMID: 33417207 DOI: 10.1007/978-3-030-60204-8_5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Peroxisomes play a central role in metabolism as exemplified by the fact that many genetic disorders in humans have been identified through the years in which there is an impairment in one or more of these peroxisomal functions, in most cases associated with severe clinical signs and symptoms. One of the key functions of peroxisomes is the β-oxidation of fatty acids which differs from the oxidation of fatty acids in mitochondria in many respects which includes the different substrate specificities of the two organelles. Whereas mitochondria are the main site of oxidation of medium-and long-chain fatty acids, peroxisomes catalyse the β-oxidation of a distinct set of fatty acids, including very-long-chain fatty acids, pristanic acid and the bile acid intermediates di- and trihydroxycholestanoic acid. Peroxisomes require the functional alliance with multiple subcellular organelles to fulfil their role in metabolism. Indeed, peroxisomes require the functional interaction with lysosomes, lipid droplets and the endoplasmic reticulum, since these organelles provide the substrates oxidized in peroxisomes. On the other hand, since peroxisomes lack a citric acid cycle as well as respiratory chain, oxidation of the end-products of peroxisomal fatty acid oxidation notably acetyl-CoA, and different medium-chain acyl-CoAs, to CO2 and H2O can only occur in mitochondria. The same is true for the reoxidation of NADH back to NAD+. There is increasing evidence that these interactions between organelles are mediated by tethering proteins which bring organelles together in order to allow effective exchange of metabolites. It is the purpose of this review to describe the current state of knowledge about the role of peroxisomes in fatty acid oxidation, the transport of metabolites across the peroxisomal membrane, its functional interaction with other subcellular organelles and the disorders of peroxisomal fatty acid β-oxidation identified so far in humans.
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Affiliation(s)
- Ronald J A Wanders
- Departments of Clinical Chemistry and Pediatrics, Amsterdam Gastroenterology Endocrinology Metabolism, Laboratory Genetic Metabolic Diseases and Emma Children's hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
| | - Frédéric M Vaz
- Departments of Clinical Chemistry and Pediatrics, Amsterdam Gastroenterology Endocrinology Metabolism, Laboratory Genetic Metabolic Diseases and Emma Children's hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Hans R Waterham
- Departments of Clinical Chemistry and Pediatrics, Amsterdam Gastroenterology Endocrinology Metabolism, Laboratory Genetic Metabolic Diseases and Emma Children's hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Sacha Ferdinandusse
- Departments of Clinical Chemistry and Pediatrics, Amsterdam Gastroenterology Endocrinology Metabolism, Laboratory Genetic Metabolic Diseases and Emma Children's hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
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68
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Castro H, Rocha MI, Silva R, Oliveira F, Gomes-Alves AG, Cruz T, Duarte M, Tomás AM. Functional insight into the glycosomal peroxiredoxin of Leishmania. Acta Trop 2020; 201:105217. [PMID: 31605692 DOI: 10.1016/j.actatropica.2019.105217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/11/2019] [Accepted: 10/08/2019] [Indexed: 01/22/2023]
Abstract
Glycosomes of trypanosomatids are peroxisome-like organelles comprising unique metabolic features, among which the lack of the hallmark peroxisomal enzyme catalase. The absence of this highly efficient peroxidase from glycosomes is presumably compensated by other antioxidants, peroxidases of the peroxiredoxin (PRX) family being the most promising candidates for this function. Here, we follow on this premise and investigate the product of a Leishmania infantum gene coding for a putative glycosomal PRX (LigPRX). First, we demonstrate that LigPRX localizes to glycosomes, resorting to indirect immunofluorescence analysis. Second, we prove that purified recombinant LigPRX is an active peroxidase in vitro. Third, we generate viable LigPRX-depleted L. infantum promastigotes by classical homologous recombination. Surprisingly, phenotypic analysis of these knockout parasites revealed that promastigote survival, replication, and protection from oxidative and nitrosative insults can proceed normally in the absence of LigPRX. Noticeably, we also witness that LigPRX-depleted parasites can infect and thrive in mice to the same extent as wild type parasites. Overall, by disclosing the dispensable character of the glycosomal peroxiredoxin in L. infantum, this work excludes this enzyme from being a key component of the glycosomal hydroperoxide metabolism and contemplates alternative players for this function.
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Affiliation(s)
- Helena Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal.
| | - Maria Inês Rocha
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Ricardo Silva
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Filipe Oliveira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Ana Georgina Gomes-Alves
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Tânia Cruz
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Margarida Duarte
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Ana Maria Tomás
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal
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Michorowska S, Giebułtowicz J, Wolinowska R, Konopka A, Wilkaniec A, Krajewski P, Bulska E, Wroczyński P. Detection of ALDH3B2 in Human Placenta. Int J Mol Sci 2019; 20:E6292. [PMID: 31847104 PMCID: PMC6941052 DOI: 10.3390/ijms20246292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 12/11/2019] [Accepted: 12/11/2019] [Indexed: 01/28/2023] Open
Abstract
Aldehyde dehydrogenase 3B2 (ALDH3B2) gene contains a premature termination codon, which can be skipped or suppressed resulting in full-length protein expression. Alternatively, the longest putative open reading frame starting with the second in-frame start codon would encode short isoform. No unequivocal evidence of ALDH3B2 expression in healthy human tissues is available. The aim of this study was to confirm its expression in human placenta characterized by the highest ALDH3B2 mRNA abundance. ALDH3B2 DNA and mRNA were sequenced. The expression was investigated using western blot. The identity of the protein was confirmed using mass spectrometry (MS). The predicted tertiary and quaternary structures, subcellular localization, and phosphorylation sites were assessed using bioinformatic analyses. All DNA and mRNA isolates contained the premature stop codon. In western blot analyses, bands corresponding to the mass of full-length protein were detected. MS analysis led to the identification of two unique peptides, one of which is encoded by the nucleotide sequence located upstream the second start codon. Bioinformatic analyses suggest cytoplasmic localization and several phosphorylation sites. Despite premature stop codon in DNA and mRNA sequences, full-length ALDH3B2 was found. It can be formed as a result of premature stop codon readthrough, complex phenomenon enabling stop codon circumvention.
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Affiliation(s)
- Sylwia Michorowska
- Department of Bioanalysis and Drug Analysis, Faculty of Pharmacy, Medical University of Warsaw, 02-097 Warsaw, Poland; (J.G.); (P.W.)
| | - Joanna Giebułtowicz
- Department of Bioanalysis and Drug Analysis, Faculty of Pharmacy, Medical University of Warsaw, 02-097 Warsaw, Poland; (J.G.); (P.W.)
| | - Renata Wolinowska
- Department of Pharmaceutical Microbiology, Centre for Preclinical Research and Technology (CePT), Faculty of Pharmacy, Medical University of Warsaw, 02-097 Warsaw, Poland;
| | - Anna Konopka
- Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, 02-097 Warsaw, Poland; (A.K.); (E.B.)
| | - Anna Wilkaniec
- Department of Cellular Signaling, Mossakowski Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland;
| | - Paweł Krajewski
- Forensic Medicine Department, First Faculty of Medicine, Medical University of Warsaw, 02-097 Warsaw, Poland;
| | - Ewa Bulska
- Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, 02-097 Warsaw, Poland; (A.K.); (E.B.)
| | - Piotr Wroczyński
- Department of Bioanalysis and Drug Analysis, Faculty of Pharmacy, Medical University of Warsaw, 02-097 Warsaw, Poland; (J.G.); (P.W.)
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70
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Staying in Healthy Contact: How Peroxisomes Interact with Other Cell Organelles. Trends Mol Med 2019; 26:201-214. [PMID: 31727543 DOI: 10.1016/j.molmed.2019.09.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/24/2019] [Accepted: 09/24/2019] [Indexed: 11/24/2022]
Abstract
Peroxisomes share extensive metabolic connections with other cell organelles. Membrane contact sites (MCSs) establish and maintain such interactions, and they are vital for organelle positioning and motility. In the past few years peroxisome interactions and MCSs with other cellular organelles have been explored extensively, resulting in the identification of new MCSs, the tethering molecules involved, and their functional characterization. Defective tethering and compartmental communication can lead to pathological conditions that can be termed 'organelle interaction diseases'. We review peroxisome-organelle interactions in mammals and summarize the most recent knowledge of mammalian peroxisomal organelle contacts in health and disease.
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Silymarin Ameliorates Acrylamide-Induced Hyperlipidemic Cardiomyopathy in Male Rats. BIOMED RESEARCH INTERNATIONAL 2019. [DOI: 10.1155/2019/4825075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Acrylamide (AA) is a well-known potent carcinogen and neurotoxin that has been recently linked to atherosclerotic pathogenesis. The present study is aimed at investigating the protective effect of silymarin (SIL) as an antioxidant against AA-induced hyperlipidemic cardiomyopathy in male rats. The obtained results showed that animals exposed to AA exhibited a significant increase in the levels of cardiac serum markers, serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol with a significant decrease in high-density lipoprotein cholesterol. Furthermore, AA intoxication significantly increased the malondialdehyde level (a hallmark of lipid peroxidation) and reduced antioxidant enzyme activities (i.e., superoxide dismutase, catalase, and glutathione peroxidase). SIL administration significantly attenuated all these biochemical perturbations in AA-treated rats, except for the decreased high-density lipoprotein cholesterol. Our results were confirmed by histopathological assessment of the myocardium. In conclusion, this study demonstrated a beneficial effect of SIL therapy in the prevention of AA-induced cardiotoxicity by reversing the redox stress and dyslipidemia in experimental animals.
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72
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Chong CS, Kunze M, Hochreiter B, Krenn M, Berger J, Maurer-Stroh S. Rare Human Missense Variants can affect the Function of Disease-Relevant Proteins by Loss and Gain of Peroxisomal Targeting Motifs. Int J Mol Sci 2019; 20:E4609. [PMID: 31533369 PMCID: PMC6770196 DOI: 10.3390/ijms20184609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/06/2019] [Accepted: 09/14/2019] [Indexed: 12/30/2022] Open
Abstract
Single nucleotide variants (SNVs) resulting in amino acid substitutions (i.e., missense variants) can affect protein localization by changing or creating new targeting signals. Here, we studied the potential of naturally occurring SNVs from the Genome Aggregation Database (gnomAD) to result in the loss of an existing peroxisomal targeting signal 1 (PTS1) or gain of a novel PTS1 leading to mistargeting of cytosolic proteins to peroxisomes. Filtering down from 32,985 SNVs resulting in missense mutations within the C-terminal tripeptide of 23,064 human proteins, based on gene annotation data and computational prediction, we selected six SNVs for experimental testing of loss of function (LoF) of the PTS1 motif and five SNVs in cytosolic proteins for gain in PTS1-mediated peroxisome import (GoF). Experimental verification by immunofluorescence microscopy for subcellular localization and FRET affinity measurements for interaction with the receptor PEX5 demonstrated that five of the six predicted LoF SNVs resulted in loss of the PTS1 motif while three of five predicted GoF SNVs resulted in de novo PTS1 generation. Overall, we showed that a complementary approach incorporating bioinformatics methods and experimental testing was successful in identifying SNVs capable of altering peroxisome protein import, which may have implications in human disease.
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Affiliation(s)
- Cheng-Shoong Chong
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore.
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore 119077, Singapore.
| | - Markus Kunze
- Medical University of Vienna, Center for Brain Research, Department of Pathobiology of the Nervous System, 1090 Vienna, Austria.
| | - Bernhard Hochreiter
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute for Vascular Biology and Thrombosis Research, 1090 Vienna, Austria.
| | - Martin Krenn
- Department of Neurology, Medical University of Vienna, 1090 Vienna, Austria.
- Institute of Human Genetics, Technical University Munich, 81675 Munich, Germany.
| | - Johannes Berger
- Medical University of Vienna, Center for Brain Research, Department of Pathobiology of the Nervous System, 1090 Vienna, Austria.
| | - Sebastian Maurer-Stroh
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore.
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore 119077, Singapore.
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore.
- Innovations in Food and Chemical Safety Programme (IFCS), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore.
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73
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Rajput B, Pruitt KD, Murphy TD. RefSeq curation and annotation of stop codon recoding in vertebrates. Nucleic Acids Res 2019; 47:594-606. [PMID: 30535227 PMCID: PMC6344875 DOI: 10.1093/nar/gky1234] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/03/2018] [Indexed: 12/23/2022] Open
Abstract
Recoding of stop codons as amino acid-specifying codons is a co-translational event that enables C-terminal extension of a protein. Synthesis of selenoproteins requires recoding of internal UGA stop codons to the 21st non-standard amino acid selenocysteine (Sec) and plays a vital role in human health and disease. Separately, canonical stop codons can be recoded to specify standard amino acids in a process known as stop codon readthrough (SCR), producing extended protein isoforms with potential novel functions. Conventional computational tools cannot distinguish between the dual functionality of stop codons as stop signals and sense codons, resulting in misannotation of selenoprotein gene products and failure to predict SCR. Manual curation is therefore required to correctly represent recoded gene products and their functions. Our goal was to provide accurately curated and annotated datasets of selenoprotein and SCR transcript and protein records to serve as annotation standards and to promote basic and biomedical research. Gene annotations were curated in nine vertebrate model organisms and integrated into NCBI's Reference Sequence (RefSeq) dataset, resulting in 247 selenoprotein genes encoding 322 selenoproteins, and 93 genes exhibiting SCR encoding 94 SCR isoforms.
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Affiliation(s)
- Bhanu Rajput
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894, USA
| | - Kim D Pruitt
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894, USA
| | - Terence D Murphy
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894, USA
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74
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Singh A, Manjunath LE, Kundu P, Sahoo S, Das A, Suma HR, Fox PL, Eswarappa SM. Let-7a-regulated translational readthrough of mammalian AGO1 generates a microRNA pathway inhibitor. EMBO J 2019; 38:e100727. [PMID: 31330067 PMCID: PMC6694283 DOI: 10.15252/embj.2018100727] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 01/01/2023] Open
Abstract
Translational readthrough generates proteins with extended C-termini, which often possess distinct properties. Here, we have used various reporter assays to demonstrate translational readthrough of AGO1 mRNA. Analysis of ribosome profiling data and mass spectrometry data provided additional evidence for translational readthrough of AGO1. The endogenous readthrough product, Ago1x, could be detected by a specific antibody both in vitro and in vivo. This readthrough process is directed by a cis sequence downstream of the canonical AGO1 stop codon, which is sufficient to drive readthrough even in a heterologous context. This cis sequence has a let-7a miRNA-binding site, and readthrough is promoted by let-7a miRNA. Interestingly, Ago1x can load miRNAs on target mRNAs without causing post-transcriptional gene silencing, due to its inability to interact with GW182. Because of these properties, Ago1x can serve as a competitive inhibitor of miRNA pathway. In support of this, we observed increased global translation in cells overexpressing Ago1x. Overall, our results reveal a negative feedback loop in the miRNA pathway mediated by the translational readthrough product of AGO1.
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Affiliation(s)
- Anumeha Singh
- Department of BiochemistryIndian Institute of ScienceBengaluruKarnatakaIndia
| | - Lekha E Manjunath
- Department of BiochemistryIndian Institute of ScienceBengaluruKarnatakaIndia
| | - Pradipta Kundu
- Department of Microbiology and Cell BiologyIndian Institute of ScienceBengaluruKarnatakaIndia
| | - Sarthak Sahoo
- Department of BiochemistryIndian Institute of ScienceBengaluruKarnatakaIndia
| | - Arpan Das
- Department of BiochemistryIndian Institute of ScienceBengaluruKarnatakaIndia
- Present address:
Department of Molecular, Cellular and Developmental BiologyUniversity of ColoradoBoulderCOUSA
| | - Harikumar R Suma
- Department of BiochemistryIndian Institute of ScienceBengaluruKarnatakaIndia
| | - Paul L Fox
- Department of Cellular and Molecular MedicineThe Lerner Research InstituteCleveland ClinicClevelandOHUSA
| | - Sandeep M Eswarappa
- Department of BiochemistryIndian Institute of ScienceBengaluruKarnatakaIndia
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75
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Liu J, Lu W, Shi B, Klein S, Su X. Peroxisomal regulation of redox homeostasis and adipocyte metabolism. Redox Biol 2019; 24:101167. [PMID: 30921635 PMCID: PMC6434164 DOI: 10.1016/j.redox.2019.101167] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 03/01/2019] [Accepted: 03/10/2019] [Indexed: 12/26/2022] Open
Abstract
Peroxisomes are ubiquitous cellular organelles required for specific pathways of fatty acid oxidation and lipid synthesis, and until recently their functions in adipocytes have not been well appreciated. Importantly, peroxisomes host many oxygen-consumption reactions and play a major role in generation and detoxification of reactive oxygen species (ROS) and reactive nitrogen species (RNS), influencing whole cell redox status. Here, we review recent progress in peroxisomal functions in lipid metabolism as related to ROS/RNS metabolism and discuss the roles of peroxisomal redox homeostasis in adipogenesis and adipocyte metabolism. We provide a framework for understanding redox regulation of peroxisomal functions in adipocytes together with testable hypotheses for developing therapies for obesity and the related metabolic diseases.
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Affiliation(s)
- Jingjing Liu
- Department of Biochemistry and Molecular Biology, Soochow University College of Medicine, Suzhou, 215123, China
| | - Wen Lu
- Department of Biochemistry and Molecular Biology, Soochow University College of Medicine, Suzhou, 215123, China; Department of Endocrinology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Bimin Shi
- Department of Endocrinology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Xiong Su
- Department of Biochemistry and Molecular Biology, Soochow University College of Medicine, Suzhou, 215123, China; Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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76
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Li C, Zhang J. Stop-codon read-through arises largely from molecular errors and is generally nonadaptive. PLoS Genet 2019; 15:e1008141. [PMID: 31120886 PMCID: PMC6550407 DOI: 10.1371/journal.pgen.1008141] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/05/2019] [Accepted: 04/16/2019] [Indexed: 12/02/2022] Open
Abstract
Stop-codon read-through refers to the phenomenon that a ribosome goes past the stop codon and continues translating into the otherwise untranslated region (UTR) of a transcript. Recent ribosome-profiling experiments in eukaryotes uncovered widespread stop-codon read-through that also varies among tissues, prompting the adaptive hypothesis that stop-codon read-through is an important, regulated mechanism for generating proteome diversity. Here we propose and test a competing hypothesis that stop-codon read-through arises mostly from molecular errors and is largely nonadaptive. The error hypothesis makes distinct predictions about the probability of read-through, frequency of sequence motifs for read-through, and conservation of the read-through region, each of which is supported by genome-scale data from yeasts and fruit flies. Thus, except for the few cases with demonstrated functions, stop-codon read-through is generally nonadaptive. This finding, along with other molecular errors recently quantified, reveals a much less precise or orderly cellular life than is commonly thought.
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Affiliation(s)
- Chuan Li
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
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77
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Abdullah IS, Teh SH, Khaidizar FD, Ngu LH, Keng WT, Yap S, Mohamed Z. Intron retention is among six unreported AGL mutations identified in Malaysian GSD III patients. Genes Genomics 2019; 41:885-893. [PMID: 31028654 DOI: 10.1007/s13258-019-00815-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 04/02/2019] [Indexed: 11/30/2022]
Abstract
BACKGROUND Glycogen storage disease type III is an autosomal recessive disorder that is caused by deficiencies of the glycogen debranching enzyme. Mutations within the AGL gene have been found to be heterogeneous, with some common mutations being reported in certain populations. The mutation spectrum of AGL gene in the multi-ethnic Malaysian population is still unknown. OBJECTIVE The present study seeks to determine the mutation spectrum of the AGL gene in Malaysian population. METHODS A total of eleven patients (eight Malay, two Chinese and one Bajau) were investigated. Genomic DNA was extracted and subsequently the AGL gene was amplified using specific primers and sequenced. Mutations found were screened in 150 healthy control samples either by restriction enzyme digestion assay or TaqMan® SNP Genotyping assay. RESULTS We identified six unreported mutations (c.1423+1G>T, c.2914_2915delAA, c.3814_3815delAG, c.4333T>G, c.4490G>A, c.4531_4534delTGTC) along with three previously reported mutations (c.99C>T, c.1783C>T, c.2681+1G>A). One of the six unreported mutation causes abnormal splicing and results in retention of intron 12 of the mature transcript, while another is a termination read-through. One of the reported mutation c.2681+1G>A was recurrently found in the Malay patients (n = 7 alleles; 31.8%). CONCLUSION The mutation spectrum of the AGL gene in Malaysian patients has shown considerable heterogeneity, and all unreported mutations were absent in all 150 healthy control samples tested.
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Affiliation(s)
- Ili Syazwana Abdullah
- Genetics and Molecular Biology Unit, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Ser-Huy Teh
- Genetics and Molecular Biology Unit, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Fiqri Dizar Khaidizar
- Centre for Research in Biotechnology for Agriculture, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Lock-Hock Ngu
- Genetics Department, Kuala Lumpur Hospital, 50586, Kuala Lumpur, Malaysia
| | - Wee-Teik Keng
- Genetics Department, Kuala Lumpur Hospital, 50586, Kuala Lumpur, Malaysia
| | - Sufin Yap
- Division of Inherited Metabolic Disorders, Department of Paediatrics, University Malaya Medical Centre and Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.,Department of Inherited Metabolic Diseases, Sheffield Children's Hospital, NHS Foundation Trust, Western Bank, S10 2TH, Sheffield, UK
| | - Zulqarnain Mohamed
- Genetics and Molecular Biology Unit, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. .,Institute of Advanced Studies, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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78
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Abstract
SIGNIFICANCE NAD+ and NADP+ are important cosubstrates in redox reactions and participate in regulatory networks operating in adjustment of metabolic pathways. Moreover, NAD+ is a cosubstrate in post-translational modification of proteins and is involved in DNA repair. NADPH is indispensable for reductive syntheses and the redox chemistry involved in attaining and maintaining correct protein conformation. Recent Advances: Within a couple of decades, a wealth of information has been gathered on NAD(H)+/NADP(H) redox imaging, regulatory role of redox potential in assembly of spatial protein structures, and the role of ADP-ribosylation of regulatory proteins affecting both gene expression and metabolism. All these have a bearing also on disease, healthy aging, and longevity. CRITICAL ISSUES Knowledge of the signal propagation pathways of NAD+-dependent post-translational modifications is still fragmentary for explaining the mechanism of cellular stress effects and nutritional state on these actions. Evaluation of the cosubstrate and regulator roles of NAD(H) and NADP(H) still suffers from some controversies in experimental data. FUTURE DIRECTIONS Activating or inhibiting interventions in NAD+-dependent protein modifications for medical purposes has shown promise, but restraining tumor growth by inhibiting DNA repair in tumors by means of interference in sirtuins is still in the early stage. The same is true for the use of this technology in improving health and healthy aging. New genetically encoded specific NAD and NADP probes are expected to modernize the research on redox biology.
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Affiliation(s)
- Ilmo E Hassinen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
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79
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Anzalone AV, Zairis S, Lin AJ, Rabadan R, Cornish VW. Interrogation of Eukaryotic Stop Codon Readthrough Signals by in Vitro RNA Selection. Biochemistry 2019; 58:1167-1178. [PMID: 30698415 DOI: 10.1021/acs.biochem.8b01280] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RNA signals located downstream of stop codons in eukaryotic mRNAs can stimulate high levels of translational readthrough by the ribosome, thereby giving rise to functionally distinct C-terminally extended protein products. Although many readthrough events have been previously discovered in Nature, a broader description of the stimulatory RNA signals would help to identify new reprogramming events in eukaryotic genes and provide insights into the molecular mechanisms of readthrough. Here, we explore the RNA reprogramming landscape by performing in vitro translation selections to enrich RNA readthrough signals de novo from a starting randomized library comprising >1013 unique sequence variants. Selection products were characterized using high-throughput sequencing, from which we identified primary sequence and secondary structure readthrough features. The activities of readthrough signals, including three novel sequence motifs, were confirmed in cellular reporter assays. Then, we used machine learning and our HTS data to predict readthrough activity from human 3'-untranslated region sequences. This led to the discovery of >1.5% readthrough in four human genes (CDKN2B, LEPROTL1, PVRL3, and SFTA2). Together, our results provide valuable insights into RNA-mediated translation reprogramming, offer tools for readthrough discovery in eukaryotic genes, and present new opportunities to explore the biological consequences of stop codon readthrough in humans.
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Affiliation(s)
- Andrew V Anzalone
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Sakellarios Zairis
- Department of Systems Biology , Columbia University , New York , New York 10032 , United States
| | - Annie J Lin
- Department of Chemistry , Columbia University , New York , New York 10027 , United States.,Department of Systems Biology , Columbia University , New York , New York 10032 , United States
| | - Raul Rabadan
- Department of Systems Biology , Columbia University , New York , New York 10032 , United States
| | - Virginia W Cornish
- Department of Chemistry , Columbia University , New York , New York 10027 , United States.,Department of Systems Biology , Columbia University , New York , New York 10032 , United States
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80
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Rogers SO. Evolution of the genetic code based on conservative changes of codons, amino acids, and aminoacyl tRNA synthetases. J Theor Biol 2019; 466:1-10. [PMID: 30658052 DOI: 10.1016/j.jtbi.2019.01.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 11/30/2022]
Abstract
The genetic code, as arranged in the standard tabular form, displays a non-random structure relating to the characteristics of the amino acids. An alternative arrangement can be made by organizing the code according to aminoacyl-tRNA synthetases (aaRSs), codons, and reverse complement codons, which illuminates a coevolutionary process that led to the contemporary genetic code. As amino acids were added to the genetic code, they were recognized by aaRSs that interact with stereochemically similar amino acids. Single nucleotide changes in the codons and anticodons were favored over more extensive changes, such that there was a logical stepwise progression in the evolution of the genetic code. The model presented traces the evolution of the genetic code accounting for these steps. Amino acid frequencies in ancient proteins and the preponderance of GNN codons in mRNAs for ancient proteins indicate that the genetic code began with alanine, aspartate, glutamate, glycine, and valine, with alanine being in the highest proportions. In addition to being consistent in terms of conservative changes in codon nucleotides, the model also is consistent with respect to aaRS classes, aaRS attachment to the tRNA, amino acid stereochemistry, and to a large extent with amino acid physicochemistry, and biochemical pathways.
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Affiliation(s)
- Scott O Rogers
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, United States.
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81
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Kamoshita N, Tominaga SI. UGA stop codon readthrough to translate intergenic region of Plautia stali intestine virus does not require RNA structures forming internal ribosomal entry site. RNA (NEW YORK, N.Y.) 2019; 25:90-104. [PMID: 30337458 PMCID: PMC6298568 DOI: 10.1261/rna.065466.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Accepted: 10/08/2018] [Indexed: 06/08/2023]
Abstract
The translation of capsid proteins of Plautia stali intestine virus (PSIV), encoded in its second open reading frame (ORF2), is directed by an internal ribosomal entry site (IRES) located in the intergenic region (IGR). Owing to the specific properties of PSIV IGR in terms of nucleotide length and frame organization, capsid proteins are also translated via stop codon readthrough in mammalian cultured cells as an extension of translation from the first ORF (ORF1) and IGR. To delineate stop codon readthrough in PSIV, we determined requirements of cis-acting elements through a molecular genetics approach applied in both cell-free translation systems and cultured cells. Mutants with deletions from the 3' end of IGR revealed that almost none of the sequence of IGR is necessary for readthrough, apart from the 5'-terminal codon CUA. Nucleotide replacement of this CUA trinucleotide or change of the termination codon from UGA severely impaired readthrough. Chemical mapping of the IGR region of the most active 3' deletion mutant indicated that this defined minimal element UGACUA, together with its downstream sequence, adopts a single-stranded conformation. Stimulatory activities of downstream RNA structures identified to date in gammaretrovirus, coltivirus, and alphavirus were not detected in the context of PSIV IGR, despite the presence of structures for IRES. To our knowledge, PSIV IGR is the first example of stop codon readthrough that is solely defined by the local hexamer sequence, even though the sequence is adjacent to an established region of RNA secondary/tertiary structures.
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Affiliation(s)
- Nobuhiko Kamoshita
- Department of Biochemistry, Jichi Medical University, Shimotsuke-shi, Tochigi-ken, 329-0498, Japan
| | - Shin-Ichi Tominaga
- Department of Biochemistry, Jichi Medical University, Shimotsuke-shi, Tochigi-ken, 329-0498, Japan
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82
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Huang X, Zhen J, Dong S, Zhang H, Van Halm-Lutterodt N, Yuan L. DHA and vitamin E antagonized the Aβ25–35-mediated neuron oxidative damage through activation of Nrf2 signaling pathways and regulation of CD36, SRB1 and FABP5 expression in PC12 cells. Food Funct 2019; 10:1049-1061. [DOI: 10.1039/c8fo01713a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The present study was designed to explore the neuroprotective effects of docosahexaenoic acid (DHA) and/or vitamin E (VE) in vitro.
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Affiliation(s)
- Xiaochen Huang
- School of Public Health
- Capital Medical University
- Beijing 100069
- P.R. China
| | - Jie Zhen
- School of Public Health
- Capital Medical University
- Beijing 100069
- P.R. China
| | - Shengqi Dong
- School of Public Health
- Capital Medical University
- Beijing 100069
- P.R. China
| | - Huiqiang Zhang
- School of Public Health
- Capital Medical University
- Beijing 100069
- P.R. China
| | | | - Linhong Yuan
- School of Public Health
- Capital Medical University
- Beijing 100069
- P.R. China
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83
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Bian Z, Ni Y, Xu JR, Liu H. A-to-I mRNA editing in fungi: occurrence, function, and evolution. Cell Mol Life Sci 2019; 76:329-340. [PMID: 30302531 PMCID: PMC11105437 DOI: 10.1007/s00018-018-2936-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 09/27/2018] [Accepted: 10/03/2018] [Indexed: 12/17/2022]
Abstract
A-to-I RNA editing is an important post-transcriptional modification that converts adenosine (A) to inosine (I) in RNA molecules via hydrolytic deamination. Although editing of mRNAs catalyzed by adenosine deaminases acting on RNA (ADARs) is an evolutionarily conserved mechanism in metazoans, organisms outside the animal kingdom lacking ADAR orthologs were thought to lack A-to-I mRNA editing. However, recent discoveries of genome-wide A-to-I mRNA editing during the sexual stage of the wheat scab fungus Fusarium graminearum, model filamentous fungus Neurospora crassa, Sordaria macrospora, and an early diverging filamentous ascomycete Pyronema confluens indicated that A-to-I mRNA editing is likely an evolutionarily conserved feature in filamentous ascomycetes. More importantly, A-to-I mRNA editing has been demonstrated to play crucial roles in different sexual developmental processes and display distinct tissue- or development-specific regulation. Contrary to that in animals, the majority of fungal RNA editing events are non-synonymous editing, which were shown to be generally advantageous and favored by positive selection. Many non-synonymous editing sites are conserved among different fungi and have potential functional and evolutionary importance. Here, we review the recent findings about the occurrence, regulation, function, and evolution of A-to-I mRNA editing in fungi.
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Affiliation(s)
- Zhuyun Bian
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Yajia Ni
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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84
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Thomas AS, Krikken AM, de Boer R, Williams C. Hansenula polymorpha Aat2p is targeted to peroxisomes via a novel Pex20p-dependent pathway. FEBS Lett 2018; 592:2466-2475. [PMID: 29924881 PMCID: PMC6099311 DOI: 10.1002/1873-3468.13168] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/25/2018] [Accepted: 06/11/2018] [Indexed: 12/29/2022]
Abstract
Saccharomyces cerevisiae Aat2p contains a peroxisomal targeting signal type‐1 and localizes to peroxisomes in oleate‐grown cells, but not in glucose‐grown cells. Here, we have investigated Aat2p from the yeast Hansenula polymorpha, which lacks a recognizable peroxisomal targeting signal. Aat2p tagged with GFP at its C terminus displays a dual cytosol‐peroxisome localization in ethanol‐grown cells. The partial peroxisomal localization of Aat2p persisted in the absence of the classical cycling receptors Pex5p and Pex7p but Aat2p targeting to peroxisomes was reduced in cells deleted for the matrix protein import factors PEX1, PEX2 and PEX13. Furthermore, we demonstrate that Aat2p targeting to peroxisomes requires Pex20p. Together, our data identify a Pex20p‐dependent pathway for targeting Aat2p to peroxisomes.
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Affiliation(s)
- Ann S Thomas
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Arjen M Krikken
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Rinse de Boer
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Chris Williams
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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85
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Cridge AG, Crowe-McAuliffe C, Mathew SF, Tate WP. Eukaryotic translational termination efficiency is influenced by the 3' nucleotides within the ribosomal mRNA channel. Nucleic Acids Res 2018; 46:1927-1944. [PMID: 29325104 PMCID: PMC5829715 DOI: 10.1093/nar/gkx1315] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 12/07/2017] [Accepted: 01/05/2018] [Indexed: 01/01/2023] Open
Abstract
When a stop codon is at the 80S ribosomal A site, there are six nucleotides (+4 to +9) downstream that are inferred to be occupying the mRNA channel. We examined the influence of these downstream nucleotides on translation termination success or failure in mammalian cells at the three stop codons. The expected hierarchy in the intrinsic fidelity of the stop codons (UAA>UAG>>UGA) was observed, with highly influential effects on termination readthrough mediated by nucleotides at position +4 and position +8. A more complex influence was observed from the nucleotides at positions +5 and +6. The weakest termination contexts were most affected by increases or decreases in the concentration of the decoding release factor (eRF1), indicating that eRF1 binding to these signals was rate-limiting. When termination efficiency was significantly reduced by cognate suppressor tRNAs, the observed influence of downstream nucleotides was maintained. There was a positive correlation between experimentally measured signal strength and frequency of the signal in eukaryotic genomes, particularly in Saccharomyces cerevisiae and Drosophila melanogaster. We propose that termination efficiency is not only influenced by interrogation of the stop signal directly by the release factor, but also by downstream ribosomal interactions with the mRNA nucleotides in the entry channel.
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Affiliation(s)
- Andrew G Cridge
- Department of Biochemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | | | - Suneeth F Mathew
- Department of Biochemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Warren P Tate
- Department of Biochemistry, University of Otago, Dunedin, Otago 9054, New Zealand
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86
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Laumont CM, Perreault C. Exploiting non-canonical translation to identify new targets for T cell-based cancer immunotherapy. Cell Mol Life Sci 2018; 75:607-621. [PMID: 28823056 PMCID: PMC11105255 DOI: 10.1007/s00018-017-2628-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/03/2017] [Accepted: 08/16/2017] [Indexed: 01/11/2023]
Abstract
Cryptic MHC I-associated peptides (MAPs) are produced via two mechanisms: translation of protein-coding genes in non-canonical reading frames and translation of allegedly non-coding sequences. In general, cryptic MAPs are coded by relatively short open reading frames whose translation can be regulated at the level of initiation, elongation or termination. In contrast to conventional MAPs, the processing of cryptic MAPs is frequently proteasome independent. The existence of cryptic MAPs derived from allegedly non-coding regions enlarges the scope of CD8 T cell immunosurveillance from a mere ~2% to as much as ~75% of the human genome. Considering that 99% of cancer-specific mutations are located in those allegedly non-coding regions, cryptic MAPs could furthermore represent a particularly rich source of tumor-specific antigens. However, extensive proteogenomic analyses will be required to determine the breath as well as the temporal and spatial plasticity of the cryptic MAP repertoire in normal and neoplastic cells.
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Affiliation(s)
- Céline M Laumont
- Institute for Research in Immunology and Cancer, Université de Montréal, Station Centre-Ville, PO Box 6128, Montreal, QC, H3C 3J7, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Station Centre-Ville, PO Box 6128, Montreal, QC, H3C 3J7, Canada
| | - Claude Perreault
- Institute for Research in Immunology and Cancer, Université de Montréal, Station Centre-Ville, PO Box 6128, Montreal, QC, H3C 3J7, Canada.
- Department of Medicine, Faculty of Medicine, Université de Montréal, Station Centre-Ville, PO Box 6128, Montreal, QC, H3C 3J7, Canada.
- Division of Hematology, Hôpital Maisonneuve-Rosemont, 5415 de l'Assomption Boulevard, Montreal, QC, H1T 2M4, Canada.
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87
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Loughran G, Jungreis I, Tzani I, Power M, Dmitriev RI, Ivanov IP, Kellis M, Atkins JF. Stop codon readthrough generates a C-terminally extended variant of the human vitamin D receptor with reduced calcitriol response. J Biol Chem 2018; 293:4434-4444. [PMID: 29386352 PMCID: PMC5868278 DOI: 10.1074/jbc.m117.818526] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 01/30/2018] [Indexed: 12/25/2022] Open
Abstract
Although stop codon readthrough is used extensively by viruses to expand their gene expression, verified instances of mammalian readthrough have only recently been uncovered by systems biology and comparative genomics approaches. Previously, our analysis of conserved protein coding signatures that extend beyond annotated stop codons predicted stop codon readthrough of several mammalian genes, all of which have been validated experimentally. Four mRNAs display highly efficient stop codon readthrough, and these mRNAs have a UGA stop codon immediately followed by CUAG (UGA_CUAG) that is conserved throughout vertebrates. Extending on the identification of this readthrough motif, we here investigated stop codon readthrough, using tissue culture reporter assays, for all previously untested human genes containing UGA_CUAG. The readthrough efficiency of the annotated stop codon for the sequence encoding vitamin D receptor (VDR) was 6.7%. It was the highest of those tested but all showed notable levels of readthrough. The VDR is a member of the nuclear receptor superfamily of ligand-inducible transcription factors, and it binds its major ligand, calcitriol, via its C-terminal ligand-binding domain. Readthrough of the annotated VDR mRNA results in a 67 amino acid-long C-terminal extension that generates a VDR proteoform named VDRx. VDRx may form homodimers and heterodimers with VDR but, compared with VDR, VDRx displayed a reduced transcriptional response to calcitriol even in the presence of its partner retinoid X receptor.
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Affiliation(s)
- Gary Loughran
- From the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland,
| | - Irwin Jungreis
- Computer Science and Artificial Intelligence Laboratory (CSAIL), Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, and
| | - Ioanna Tzani
- From the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Michael Power
- From the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Ruslan I Dmitriev
- From the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Ivaylo P Ivanov
- From the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Manolis Kellis
- Computer Science and Artificial Intelligence Laboratory (CSAIL), Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, and
| | - John F Atkins
- From the School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland, .,Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112-5330
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88
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Yordanova MM, Loughran G, Zhdanov AV, Mariotti M, Kiniry SJ, O'Connor PBF, Andreev DE, Tzani I, Saffert P, Michel AM, Gladyshev VN, Papkovsky DB, Atkins JF, Baranov PV. AMD1 mRNA employs ribosome stalling as a mechanism for molecular memory formation. Nature 2018; 553:356-360. [PMID: 29310120 DOI: 10.1038/nature25174] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 11/28/2017] [Indexed: 11/09/2022]
Abstract
In addition to acting as template for protein synthesis, messenger RNA (mRNA) often contains sensory sequence elements that regulate this process. Here we report a new mechanism that limits the number of complete protein molecules that can be synthesized from a single mRNA molecule of the human AMD1 gene encoding adenosylmethionine decarboxylase 1 (AdoMetDC). A small proportion of ribosomes translating AMD1 mRNA stochastically read through the stop codon of the main coding region. These readthrough ribosomes then stall close to the next in-frame stop codon, eventually forming a ribosome queue, the length of which is proportional to the number of AdoMetDC molecules that were synthesized from the same AMD1 mRNA. Once the entire spacer region between the two stop codons is filled with queueing ribosomes, the queue impinges upon the main AMD1 coding region halting its translation. Phylogenetic analysis suggests that this mechanism is highly conserved in vertebrates and existed in their common ancestor. We propose that this mechanism is used to count and limit the number of protein molecules that can be synthesized from a single mRNA template. It could serve to safeguard from dysregulated translation that may occur owing to errors in transcription or mRNA damage.
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Affiliation(s)
- Martina M Yordanova
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Gary Loughran
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Alexander V Zhdanov
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Marco Mariotti
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland.,Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Stephen J Kiniry
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Patrick B F O'Connor
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Dmitry E Andreev
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ioanna Tzani
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Paul Saffert
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Audrey M Michel
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Dmitry B Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
| | - John F Atkins
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland.,Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112, USA
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YN60, Ireland
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89
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Freitag J, Stehlik T, Stiebler AC, Bölker M. The Obvious and the Hidden: Prediction and Function of Fungal Peroxisomal Matrix Proteins. Subcell Biochem 2018; 89:139-155. [PMID: 30378022 DOI: 10.1007/978-981-13-2233-4_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Fungal peroxisomes are characterized by a number of specific biological functions. To understand the physiology and biochemistry of these organelles knowledge of the proteome content is crucial. Here, we address different strategies to predict peroxisomal proteins by bioinformatics approaches. These tools range from simple text searches to network based learning strategies. A complication of this analysis is the existence of cryptic peroxisomal proteins, which are overlooked in conventional bioinformatics queries. These include proteins where targeting information results from transcriptional and posttranscriptional alterations. But also proteins with low efficiency targeting motifs that are predominantly localized in the cytosol, and proteins lacking any canonical targeting information, can play important roles within peroxisomes. Many of these proteins are so far unpredictable. Detection and characterization of these cryptic peroxisomal proteins revealed the presence of novel peroxisomal enzymatic reaction networks in fungi.
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Affiliation(s)
- Johannes Freitag
- Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Thorsten Stehlik
- Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Alina C Stiebler
- Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Michael Bölker
- Department of Biology, Philipps-Universität Marburg, Marburg, Germany.
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90
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Kunze M. Predicting Peroxisomal Targeting Signals to Elucidate the Peroxisomal Proteome of Mammals. Subcell Biochem 2018; 89:157-199. [PMID: 30378023 DOI: 10.1007/978-981-13-2233-4_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Peroxisomes harbor a plethora of proteins, but the peroxisomal proteome as the entirety of all peroxisomal proteins is still unknown for mammalian species. Computational algorithms can be used to predict the subcellular localization of proteins based on their amino acid sequence and this method has been amply used to forecast the intracellular fate of individual proteins. However, when applying such algorithms systematically to all proteins of an organism the prediction of its peroxisomal proteome in silico should be possible. Therefore, a reliable detection of peroxisomal targeting signals (PTS ) acting as postal codes for the intracellular distribution of the encoding protein is crucial. Peroxisomal proteins can utilize different routes to reach their destination depending on the type of PTS. Accordingly, independent prediction algorithms have been developed for each type of PTS, but only those for type-1 motifs (PTS1) have so far reached a satisfying predictive performance. This is partially due to the low number of peroxisomal proteins limiting the power of statistical analyses and partially due to specific properties of peroxisomal protein import, which render functional PTS motifs inactive in specific contexts. Moreover, the prediction of the peroxisomal proteome is limited by the high number of proteins encoded in mammalian genomes, which causes numerous false positive predictions even when using reliable algorithms and buries the few yet unidentified peroxisomal proteins. Thus, the application of prediction algorithms to identify all peroxisomal proteins is currently ineffective as stand-alone method, but can display its full potential when combined with other methods.
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Affiliation(s)
- Markus Kunze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria.
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91
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Bersch K, Lobos Matthei I, Thoms S. Multiple Localization by Functional Translational Readthrough. Subcell Biochem 2018; 89:201-219. [PMID: 30378024 DOI: 10.1007/978-981-13-2233-4_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In a compartmentalized cell, correct protein localization is crucial for function of virtually all cellular processes. From the cytoplasm as a starting point, proteins are imported into organelles by specific targeting signals. Many proteins, however, act in more than one cellular compartment. In this chapter, we discuss mechanisms by which proteins can be targeted to multiple organelles with a focus on a novel gene regulatory mechanism, functional translational readthrough, that permits multiple targeting of proteins to the peroxisome and other organelles. In mammals, lactate and malate dehydrogenase are the best-characterized enzymes whose targeting is controlled by functional translational readthrough.
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Affiliation(s)
- Kristina Bersch
- Department of Child and Adolescent Health, University Medical Center Göttingen, University of Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Ignacio Lobos Matthei
- Department of Child and Adolescent Health, University Medical Center Göttingen, University of Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Sven Thoms
- Department of Child and Adolescent Health, University Medical Center Göttingen, University of Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany.
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92
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Abstract
The current view on peroxisomes has changed dramatically from being human cell oddities to vital organelles that host several key metabolic pathways. To fulfil over 50 different enzymatic functions, human peroxisomes host either unique peroxisomal proteins or dual-localized proteins. The identification and characterization of the complete peroxisomal proteome in humans is important for diagnosis and treatment of patients with peroxisomal disorders as well as for uncovering novel peroxisomal functions and regulatory modules. Hence, here we compiled a comprehensive list of mammalian peroxisomal and peroxisome-associated proteins by curating results of several quantitative and non-quantitative proteomic studies together with entries in the UniProtKB and Compartments knowledge channel databases. Our analysis gives a holistic view on the mammalian peroxisomal proteome and brings to light potential new peroxisomal and peroxisome-associated proteins. We believe that this dataset, represents a valuable surrogate map of the human peroxisomal proteome.
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93
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Hofhuis J, Schueren F, Nötzel C, Lingner T, Gärtner J, Jahn O, Thoms S. The functional readthrough extension of malate dehydrogenase reveals a modification of the genetic code. Open Biol 2017; 6:rsob.160246. [PMID: 27881739 PMCID: PMC5133446 DOI: 10.1098/rsob.160246] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 10/21/2016] [Indexed: 01/19/2023] Open
Abstract
Translational readthrough gives rise to C-terminally extended proteins, thereby providing the cell with new protein isoforms. These may have different properties from the parental proteins if the extensions contain functional domains. While for most genes amino acid incorporation at the stop codon is far lower than 0.1%, about 4% of malate dehydrogenase (MDH1) is physiologically extended by translational readthrough and the actual ratio of MDH1x (extended protein) to ‘normal' MDH1 is dependent on the cell type. In human cells, arginine and tryptophan are co-encoded by the MDH1x UGA stop codon. Readthrough is controlled by the 7-nucleotide high-readthrough stop codon context without contribution of the subsequent 50 nucleotides encoding the extension. All vertebrate MDH1x is directed to peroxisomes via a hidden peroxisomal targeting signal (PTS) in the readthrough extension, which is more highly conserved than the extension of lactate dehydrogenase B. The hidden PTS of non-mammalian MDH1x evolved to be more efficient than the PTS of mammalian MDH1x. These results provide insight into the genetic and functional co-evolution of these dually localized dehydrogenases.
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Affiliation(s)
- Julia Hofhuis
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, University of Göttingen, 37075 Göttingen, Germany
| | - Fabian Schueren
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, University of Göttingen, 37075 Göttingen, Germany
| | - Christopher Nötzel
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, University of Göttingen, 37075 Göttingen, Germany
| | - Thomas Lingner
- Microarray and Deep Sequencing Core Facility, University Medical Center Göttingen, University of Göttingen, 37077 Göttingen, Germany
| | - Jutta Gärtner
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, University of Göttingen, 37075 Göttingen, Germany
| | - Olaf Jahn
- Proteomics Group, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Sven Thoms
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, University of Göttingen, 37075 Göttingen, Germany
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94
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Loughran G, Howard MT, Firth AE, Atkins JF. Avoidance of reporter assay distortions from fused dual reporters. RNA (NEW YORK, N.Y.) 2017; 23:1285-1289. [PMID: 28442579 PMCID: PMC5513072 DOI: 10.1261/rna.061051.117] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/19/2017] [Indexed: 06/07/2023]
Abstract
Positioning test sequences between fused reporters permits monitoring of both translation levels and framing, before and after the test sequence. Many studies, including those on recoding such as productive ribosomal frameshifting and stop codon readthrough, use distinguishable luciferases or fluorescent proteins as reporters. Occasional distortions, due to test sequence product interference with the individual reporter activities or stabilities, are here shown to be avoidable by the introduction of tandem StopGo sequences (2A) flanking the test sequence. Using this new vector system (pSGDluc), we provide evidence for the use of a 3' stem-loop stimulator for ACP2 readthrough, but failed to detect the reported VEGFA readthrough.
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Affiliation(s)
- Gary Loughran
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YT57, Ireland
| | - Michael T Howard
- Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112, USA
| | - Andrew E Firth
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - John F Atkins
- School of Biochemistry and Cell Biology, University College Cork, Cork T12 YT57, Ireland
- Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112, USA
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95
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An C, Gao Y, Li J, Liu X, Gao F, Gao H. Alternative splicing affects the targeting sequence of peroxisome proteins in Arabidopsis. PLANT CELL REPORTS 2017; 36:1027-1036. [PMID: 28352967 DOI: 10.1007/s00299-017-2131-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/10/2017] [Indexed: 06/06/2023]
Abstract
A systematic analysis of the Arabidopsis genome in combination with localization experiments indicates that alternative splicing affects the peroxisomal targeting sequence of at least 71 genes in Arabidopsis. Peroxisomes are ubiquitous eukaryotic cellular organelles that play a key role in diverse metabolic functions. All peroxisome proteins are encoded by nuclear genes and target to peroxisomes mainly through two types of targeting signals: peroxisomal targeting signal type 1 (PTS1) and PTS2. Alternative splicing (AS) is a process occurring in all eukaryotes by which a single pre-mRNA can generate multiple mRNA variants, often encoding proteins with functional differences. However, the effects of AS on the PTS1 or PTS2 and the targeting of the protein were rarely studied, especially in plants. Here, we systematically analyzed the genome of Arabidopsis, and found that the C-terminal targeting sequence PTS1 of 66 genes and the N-terminal targeting sequence PTS2 of 5 genes are affected by AS. Experimental determination of the targeting of selected protein isoforms further demonstrated that AS at both the 5' and 3' region of a gene can affect the inclusion of PTS2 and PTS1, respectively. This work underscores the importance of AS on the global regulation of peroxisome protein targeting.
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Affiliation(s)
- Chuanjing An
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Yuefang Gao
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Jinyu Li
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Xiaomin Liu
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Fuli Gao
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Hongbo Gao
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China.
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96
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Cipolla CM, Lodhi IJ. Peroxisomal Dysfunction in Age-Related Diseases. Trends Endocrinol Metab 2017; 28:297-308. [PMID: 28063767 PMCID: PMC5366081 DOI: 10.1016/j.tem.2016.12.003] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/04/2016] [Accepted: 12/07/2016] [Indexed: 12/21/2022]
Abstract
Peroxisomes carry out many key functions related to lipid and reactive oxygen species (ROS) metabolism. The fundamental importance of peroxisomes for health in humans is underscored by the existence of devastating genetic disorders caused by impaired peroxisomal function or lack of peroxisomes. Emerging studies suggest that peroxisomal function may also be altered with aging and contribute to the pathogenesis of a variety of diseases, including diabetes and its related complications, neurodegenerative disorders, and cancer. With increasing evidence connecting peroxisomal dysfunction to the pathogenesis of these acquired diseases, the possibility of targeting peroxisomal function in disease prevention or treatment becomes intriguing. Here, we review recent developments in understanding the pathophysiological implications of peroxisomal dysfunctions outside the context of inherited peroxisomal disorders.
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Affiliation(s)
- Cynthia M Cipolla
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Irfan J Lodhi
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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97
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Kompella PS, Moses AM, Peisajovich SG. Introduction of Premature Stop Codons as an Evolutionary Strategy To Rescue Signaling Network Function. ACS Synth Biol 2017; 6:446-454. [PMID: 27935292 DOI: 10.1021/acssynbio.6b00142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The cellular concentrations of key components of signaling networks are tightly regulated, as deviations from their optimal ranges can have negative effects on signaling function. For example, overexpression of the yeast mating pathway mitogen-activated protein kinase (MAPK) Fus3 decreases pathway output, in part by sequestering individual components away from functional multiprotein complexes. Using a synthetic biology approach, we investigated potential mechanisms by which selection could compensate for a decrease in signaling activity caused by overexpression of Fus3. We overexpressed a library of random mutants of Fus3 and used cell sorting to select variants that rescued mating pathway activity. Our results uncovered that one remarkable way in which selection can compensate for protein overexpression is by introducing premature stop codons at permitted positions. Because of the low efficiency with which premature stop codons are read through, the resulting cellular concentration of active Fus3 returns to values within the range required for proper signaling. Our results underscore the importance of interpreting genotypic variation at the systems rather than at the individual gene level, as mutations can have opposite effects on protein and network function.
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Affiliation(s)
- Purnima S. Kompella
- Department of Cell and Systems
Biology, University of Toronto 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
| | - Alan M. Moses
- Department of Cell and Systems
Biology, University of Toronto 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
| | - Sergio G. Peisajovich
- Department of Cell and Systems
Biology, University of Toronto 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
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98
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Saryi NAA, Hutchinson JD, Al-Hejjaj MY, Sedelnikova S, Baker P, Hettema EH. Pnc1 piggy-back import into peroxisomes relies on Gpd1 homodimerisation. Sci Rep 2017; 7:42579. [PMID: 28209961 PMCID: PMC5314374 DOI: 10.1038/srep42579] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/29/2016] [Indexed: 12/17/2022] Open
Abstract
Peroxisomes are eukaryotic organelles that posttranslationally import proteins via one of two conserved peroxisomal targeting signal (PTS1 or 2) mediated pathways. Oligomeric proteins can be imported via these pathways but evidence is accumulating that at least some PTS1-containing monomers enter peroxisomes before they assemble into oligomers. Some proteins lacking a PTS are imported by piggy-backing onto PTS-containing proteins. One of these proteins is the nicotinamidase Pnc1, that is co-imported with the PTS2-containing enzyme Glycerol-3-phosphate dehydrogenase 1, Gpd1. Here we show that Pnc1 co-import requires Gpd1 to form homodimers. A mutation that interferes with Gpd1 homodimerisation does not prevent Gpd1 import but prevents Pnc1 co-import. A suppressor mutation that restores Gpd1 homodimerisation also restores Pnc1 co-import. In line with this, Pnc1 interacts with Gpd1 in vivo only when Gpd1 can form dimers. Redirection of Gpd1 from the PTS2 import pathway to the PTS1 import pathway supports Gpd1 monomer import but not Gpd1 homodimer import and Pnc1 co-import. Our results support a model whereby Gpd1 may be imported as a monomer or a dimer but only the Gpd1 dimer facilitates co-transport of Pnc1 into peroxisomes.
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Affiliation(s)
- Nadal A Al Saryi
- Department of Molecular Biology and Biotechnology University of Sheffield Firth Court, Western Bank Sheffield S10 2TN United Kingdom
| | - John D Hutchinson
- Department of Molecular Biology and Biotechnology University of Sheffield Firth Court, Western Bank Sheffield S10 2TN United Kingdom
| | - Murtakab Y Al-Hejjaj
- Department of Molecular Biology and Biotechnology University of Sheffield Firth Court, Western Bank Sheffield S10 2TN United Kingdom
| | - Svetlana Sedelnikova
- Department of Molecular Biology and Biotechnology University of Sheffield Firth Court, Western Bank Sheffield S10 2TN United Kingdom
| | - Patrick Baker
- Department of Molecular Biology and Biotechnology University of Sheffield Firth Court, Western Bank Sheffield S10 2TN United Kingdom
| | - Ewald H Hettema
- Department of Molecular Biology and Biotechnology University of Sheffield Firth Court, Western Bank Sheffield S10 2TN United Kingdom
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99
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De Bellis M, Pisani F, Mola MG, Rosito S, Simone L, Buccoliero C, Trojano M, Nicchia GP, Svelto M, Frigeri A. Translational readthrough generates new astrocyte AQP4 isoforms that modulate supramolecular clustering, glial endfeet localization, and water transport. Glia 2017; 65:790-803. [PMID: 28206694 DOI: 10.1002/glia.23126] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/02/2017] [Accepted: 01/25/2017] [Indexed: 11/10/2022]
Abstract
Regulation of water homeostasis is a central feature of central nervous system pathophysiology. In this context, several lines of evidence suggest a crucial role for the water channel aquaporin-4 (AQP4) and its plasma membrane supramolecular organization as the key element. Here, we demonstrate the expression in tissues of additional isoforms of AQP4 characterized by a C-terminal extension generated by programmed translational readthrough. These extended isoforms (AQP4ex) display a perivascular polarization and expression in dystrophin-dependent pools. AQP4ex reduces supramolecular clustering tendency and allows AQP4 interactions with syntrophin. Furthermore, site-directed mutagenesis of two serines in the extended C-terminus of AQP4ex showed potential regulation of water permeability by phosphorylation. Finally, AQP4ex expression can be positively modulated by gentamicin treatment, demonstrating the possibility of regulating the AQP4 translational readthrough frequency. This novel regulatory mechanism could have important pathophysiological implications for conditions in which alternations have been reported in AQP4 structure.
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Affiliation(s)
- Manuela De Bellis
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Francesco Pisani
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Maria Grazia Mola
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Stefania Rosito
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Laura Simone
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy.,IRCCS "Casa Sollievo della Sofferenza", Research Hospital, San Giovanni Rotondo, Foggia, Italy
| | - Cinzia Buccoliero
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Maria Trojano
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy.,Dominick P. Purpura Department of Neuroscience, 840 Kennedy Center, Bronx, New York
| | - Maria Svelto
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Antonio Frigeri
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Bari, Italy.,Dominick P. Purpura Department of Neuroscience, 840 Kennedy Center, Bronx, New York
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100
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Hofhuis J, Dieterle S, George R, Schueren F, Thoms S. Dual Reporter Systems for the Analysis of Translational Readthrough in Mammals. Methods Mol Biol 2017; 1595:81-92. [PMID: 28409454 DOI: 10.1007/978-1-4939-6937-1_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Translational readthrough, the decoding of stop codons as sense codons, leads to C-terminal extension of proteins which may lead to the formation of protein isoforms with distinct properties from the original protein. Two proteins have recently been identified that are targeted to the peroxisome via hidden peroxisomal targeting signals in their readthrough extensions. This noninduced basal translational readthrough can be distinguished from pharmacological induction of readthrough by aminoglycosides or other small molecules, which can be used for the treatment of diseases caused by premature stop (termination) codons (PTCs). Readthrough of both, natural stop codons and PTCs, can be quantified in cell culture using reporter systems. In the present article, we describe two dual reporter systems, based on combined fluorescence/luminescence measurement and flow cytometric fluorescence measurement, respectively. Further, we provide a protocol for a fast and efficient cloning procedure of reporter constructs. The dual reporter systems described here help to analyze the peroxisome-specific isoforms of readthrough enzymes as well as potential readthrough therapeutics.
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Affiliation(s)
- Julia Hofhuis
- Department of Pediatrics and Adolescent Health, University Medical Center G&ttingen, University of G&ttingen, Robert-Koch-Strasse 40, D-37075, G&ttingen, Germany
| | - Severin Dieterle
- Department of Pediatrics and Adolescent Health, University Medical Center G&ttingen, University of G&ttingen, Robert-Koch-Strasse 40, D-37075, G&ttingen, Germany
| | - Rosemol George
- Department of Pediatrics and Adolescent Health, University Medical Center G&ttingen, University of G&ttingen, Robert-Koch-Strasse 40, D-37075, G&ttingen, Germany
| | - Fabian Schueren
- Department of Pediatrics and Adolescent Health, University Medical Center G&ttingen, University of G&ttingen, Robert-Koch-Strasse 40, D-37075, G&ttingen, Germany
| | - Sven Thoms
- Department of Pediatrics and Adolescent Health, University Medical Center G&ttingen, University of G&ttingen, Robert-Koch-Strasse 40, D-37075, G&ttingen, Germany. &ttingen.de
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