1
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Jaconi M, Magni F, Raimondo F, Ponzoni M, Chinello C, Smith A, Piga I, Fusco N, Di Bella C, Pagni F. TdT expression in germ cell tumours: a possible immunohistochemical cross-reaction and diagnostic pitfall. J Clin Pathol 2019; 72:536-541. [PMID: 31055472 DOI: 10.1136/jclinpath-2019-205713] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 04/12/2019] [Accepted: 04/13/2019] [Indexed: 11/04/2022]
Abstract
AIMS Very recent papers proposed a possible role for the expression of terminal deoxynucleotidyl transferase (TdT) in the tumourigenesis of gonadal and extragonadal germ cell-derived tumours (GCTs). Our multicentric study evaluated the magnitude of the immunoreactivity for TdT in GCTs, encompassing seminoma, dysgerminoma, mature teratoma and mixed GCTs. METHODS AND RESULTS The histological series was stained with both monoclonal and polyclonal antibodies, yielding a positivity of 80% of cases with well-defined nuclear reactivity. A significant difference in staining intensity between monoclonal and polyclonal antibodies was observed (p=0.005). However, exploiting western blot and more innovative proteomic approaches, no clear-cut evidence of the TdT protein was observed in the neoplastic tissues of the series. CONCLUSIONS Alternatively to the pathogenetic link between TdT expression and GCTs tumourigenesis, we hypothesised the occurrence of a spurious immunohistochemical nuclear cross-reaction, a well-known phenomenon with important implications and a possible source of diagnostic pitfalls in routine practice for pathologists.
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Affiliation(s)
- Marta Jaconi
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Fulvio Magni
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Francesca Raimondo
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | | | - Clizia Chinello
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Andrew Smith
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Isabella Piga
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Nicola Fusco
- Division of Pathology, Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Camillo Di Bella
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Fabio Pagni
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
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2
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Funck T, Barnkob MB, Holm N, Ohm-Laursen L, Mehlum CS, Möller S, Barington T. Nucleotide Composition of Human Ig Nontemplated Regions Depends on Trimming of the Flanking Gene Segments, and Terminal Deoxynucleotidyl Transferase Favors Adding Cytosine, Not Guanosine, in Most VDJ Rearrangements. THE JOURNAL OF IMMUNOLOGY 2018; 201:1765-1774. [PMID: 30097530 DOI: 10.4049/jimmunol.1800100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 07/05/2018] [Indexed: 01/12/2023]
Abstract
The formation of nontemplated (N) regions during Ig gene rearrangement is a major contributor to Ab diversity. To gain insights into the mechanisms behind this, we studied the nucleotide composition of N regions within 29,962 unique human VHDJH rearrangements and 8728 unique human DJH rearrangements containing exactly one identifiable D gene segment and thus two N regions, N1 and N2. We found a distinct decreasing content of cytosine (C) and increasing content of guanine (G) across each N region, suggesting that N regions are typically generated by concatenation of two 3' overhangs synthesized by addition of nucleoside triphosphates with a preference for dCTP. This challenges the general assumption that the terminal deoxynucleotidyl transferase favors dGTP in vivo. Furthermore, we found that the G and C gradients depended strongly on whether the germline gene segments were trimmed or not. Our data show that C-enriched N addition preferentially happens at trimmed 3' ends of VH, D, and JH gene segments, indicating a dependency of the transferase mechanism upon the nuclease mechanism.
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Affiliation(s)
- Tina Funck
- Department of Clinical Biochemistry, Zealand University Hospital, Roskilde 4000, Denmark.,Department of Clinical Immunology, Odense University Hospital, Odense 5000, Denmark
| | - Mike Bogetofte Barnkob
- Department of Clinical Immunology, Odense University Hospital, Odense 5000, Denmark.,Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxfordshire OX3 9DS, United Kingdom
| | - Nanna Holm
- Department of Clinical Immunology, Odense University Hospital, Odense 5000, Denmark
| | - Line Ohm-Laursen
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, United Kingdom
| | - Camilla Slot Mehlum
- Department of Otorhinolaryngology-Head and Neck Surgery, Odense University Hospital, Odense 5000, Denmark
| | - Sören Möller
- OPEN, Odense Patient Data Explorative Network, Odense University Hospital, Odense 5000, Denmark; and.,Clinical Department, University of Southern Denmark, Odense 5000, Denmark
| | - Torben Barington
- Department of Clinical Immunology, Odense University Hospital, Odense 5000, Denmark; .,Clinical Department, University of Southern Denmark, Odense 5000, Denmark
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3
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Prediction of Disordered Regions and Their Roles in the Anti-Pathogenic and Immunomodulatory Functions of Butyrophilins. Molecules 2018; 23:molecules23020328. [PMID: 29401697 PMCID: PMC6017450 DOI: 10.3390/molecules23020328] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 12/13/2022] Open
Abstract
Butyrophilins (BTNs) are a group of the moonlighting proteins, some members of which are secreted in milk. They constitute a large family of structurally similar type 1 transmembrane proteins from the immunoglobulin superfamily. Although the founding member of this family is related to lactation, participating in the secretion, formation and stabilization of milk fat globules, it may also have a cell surface receptor function. Generally, the BTN family members are known to modulate co-stimulatory responses, T cell selection, differentiation, and cell fate determination. Polymorphism of these genes was shown to be associated with the pathology of several human diseases. Despite their biological significance, structural information on human butyrophilins is rather limited. Based on their remarkable multifunctionality, butyrophilins seem to belong to the category of moonlighting proteins, which are known to contain intrinsically disordered protein regions (IDPRs). However, the disorder status of human BTNs was not systematically investigated as of yet. The goal of this study is to fill this gap and to evaluate peculiarities of intrinsic disorder predisposition of the members of human BTN family, and to find if they have IDPRs that can be attributed to the multifunctionality of these important proteins.
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4
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Darling AL, Liu Y, Oldfield CJ, Uversky VN. Intrinsically Disordered Proteome of Human Membrane-Less Organelles. Proteomics 2017; 18:e1700193. [PMID: 29068531 DOI: 10.1002/pmic.201700193] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 02/10/2017] [Indexed: 11/10/2022]
Abstract
It is recognized now that various proteinaceous membrane-less organelles (PMLOs) are commonly found in cytoplasm, nucleus, and mitochondria of various eukaryotic cells (as well as in the chloroplasts of plant cells). Being different from the "traditional" membrane-encapsulated organelles, such as chloroplasts, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, nucleus, and vacuoles, PMLOs solve the cellular need to facilitate and regulate molecular interactions via reversible and controllable isolation of target molecules in specialized compartments. PMLOs possess liquid-like behavior and are believed to be formed as a result of biological liquid-liquid phase transitions (LLPTs, also known as liquid-liquid phase separation), where an intricate interplay between RNA and intrinsically disordered proteins (IDPs) or hybrid proteins containing ordered domains and intrinsically disordered protein regions (IDPRs) may play an important role. This review analyzes the prevalence of intrinsic disorder in proteins associated with various PMLOs found in human cells and considers some of the functional roles of IDPs/IDPRs in biogenesis of these organelles.
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Affiliation(s)
- April L Darling
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Yun Liu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, P. R. China
| | | | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Institute for Biological Instrumentation, Russian Academy of Sciences, Moscow Region, Russia
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5
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Gomez-Tourino I, Kamra Y, Baptista R, Lorenc A, Peakman M. T cell receptor β-chains display abnormal shortening and repertoire sharing in type 1 diabetes. Nat Commun 2017; 8:1792. [PMID: 29176645 PMCID: PMC5702608 DOI: 10.1038/s41467-017-01925-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 10/25/2017] [Indexed: 01/10/2023] Open
Abstract
Defects in T cell receptor (TCR) repertoire are proposed to predispose to autoimmunity. Here we show, by analyzing >2 × 108TCRB sequences of circulating naive, central memory, regulatory and stem cell-like memory CD4+ T cell subsets from patients with type 1 diabetes and healthy donors, that patients have shorter TCRB complementarity-determining region 3s (CDR3), in all cell subsets, introduced by increased deletions/reduced insertions during VDJ rearrangement. High frequency of short CDR3s is also observed in unproductive TCRB sequences, which are not subjected to thymic culling, suggesting that the shorter CDR3s arise independently of positive/negative selection. Moreover, TCRB CDR3 clonotypes expressed by autoantigen-specific CD4+ T cells are shorter compared with anti-viral T cells, and with those from healthy donors. Thus, early events in thymic T cell development and repertoire generation are abnormal in type 1 diabetes, which suggest that short CDR3s increase the potential for self-recognition, conferring heightened risk of autoimmune disease. T cell receptors are generated by somatic gene recombination, and are normally selected against autoreactivity. Here the authors show that CD4 T cells from patients with autoimmune type 1 diabetes have shorter TCRβ sequences, broader repertoire diversity, and more repertoire sharing than those from healthy individuals.
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Affiliation(s)
- Iria Gomez-Tourino
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, 2nd Floor, Borough Wing, Guy's Hospital, London, SE1 9RT, UK.,National Institute for Health Research, Biomedical Research Centre at Guy's and St Thomas' Hospital Foundation Trust and King's College London, Guy's Hospital, London, SE1 9RT, UK.,Immunology Laboratory, Biomedical Research Center (CINBIO), Centro Singular de Investigación de Galicia, University of Vigo, Campus Universitario de Vigo, Pontevedra, 36310, Spain
| | - Yogesh Kamra
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, 2nd Floor, Borough Wing, Guy's Hospital, London, SE1 9RT, UK
| | - Roman Baptista
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, 2nd Floor, Borough Wing, Guy's Hospital, London, SE1 9RT, UK.,National Institute for Health Research, Biomedical Research Centre at Guy's and St Thomas' Hospital Foundation Trust and King's College London, Guy's Hospital, London, SE1 9RT, UK
| | - Anna Lorenc
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, 2nd Floor, Borough Wing, Guy's Hospital, London, SE1 9RT, UK
| | - Mark Peakman
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, 2nd Floor, Borough Wing, Guy's Hospital, London, SE1 9RT, UK. .,National Institute for Health Research, Biomedical Research Centre at Guy's and St Thomas' Hospital Foundation Trust and King's College London, Guy's Hospital, London, SE1 9RT, UK.
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6
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Huang Y, Cai J, Tang JF, Zhang HY, Wang ZW, Jian JC, Wu ZH, Lu YS. Identification and expression analysis of terminal deoxynucleotidyl transferase in humphead snapper Lutjanus sanguineus. JOURNAL OF FISH BIOLOGY 2017; 90:2194-2199. [PMID: 28369937 DOI: 10.1111/jfb.13259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 11/30/2016] [Indexed: 06/07/2023]
Abstract
A tdt gene was identified successfully from humphead snapper Lutjanus sanguineus, which contained 1710 bp encoding a protein of 463 amino acids. Results of quantitative real-time polymerase chain reaction (qRT-PCR) indicated that tdt mainly expressed in thymus and head kidney and the transcripts of tdt in these tissues were up-regulated significantly at 36 and 48 h after Vibrio harveyi infection. Meanwhile Tdt-producing cells were found in thymus and head kidney.
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Affiliation(s)
- Y Huang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - J Cai
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - J F Tang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - H Y Zhang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - Z W Wang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - J C Jian
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - Z H Wu
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - Y S Lu
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
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7
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Application of Immunohistochemistry in Toxicologic Pathology of the Hematolymphoid System. IMMUNOPATHOLOGY IN TOXICOLOGY AND DRUG DEVELOPMENT 2017. [DOI: 10.1007/978-3-319-47377-2_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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8
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Troshchynsky A, Dzneladze I, Chen L, Sheng Y, Saridakis V, Wu GE. Functional analyses of polymorphic variants of human terminal deoxynucleotidyl transferase. Genes Immun 2015; 16:388-98. [PMID: 26043173 DOI: 10.1038/gene.2015.19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 04/19/2015] [Accepted: 04/23/2015] [Indexed: 12/11/2022]
Abstract
Human terminal deoxynucleotidyl transferase (hTdT) is a DNA polymerase that functions to generate diversity in the adaptive immune system. Here, we focus on the function of naturally occurring single-nucleotide polymorphisms (SNPs) of hTdT to evaluate their role in genetic-generated immune variation. The data demonstrate that the genetic variations generated by the hTdT SNPs will vary the human immune repertoire and thus its responses. Human TdT catalyzes template-independent addition of nucleotides (N-additions) during coding joint formation in V(D)J recombination. Its activity is crucial to the diversity of the antigen receptors of B and T lymphocytes. We used in vitro polymerase assays and in vivo human cell V(D)J recombination assays to evaluate the activity and the N-addition levels of six natural (SNP) variants of hTdT. In vitro, the variants differed from wild-type hTdT in polymerization ability with four having significantly lower activity. In vivo, the presence of TdT varied both the efficiency of recombination and N-addition, with two variants generating coding joints with significantly fewer N-additions. Although likely heterozygous, individuals possessing these genetic changes may have less diverse B- and T-cell receptors that would particularly effect individuals prone to adaptive immune disorders, including autoimmunity.
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Affiliation(s)
- A Troshchynsky
- Department of Biology, York University, Toronto, Ontario, Canada
| | - I Dzneladze
- Department of Biology, York University, Toronto, Ontario, Canada
| | - L Chen
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Y Sheng
- Department of Biology, York University, Toronto, Ontario, Canada
| | - V Saridakis
- Department of Biology, York University, Toronto, Ontario, Canada
| | - G E Wu
- Department of Biology, York University, Toronto, Ontario, Canada.,School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.,School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
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9
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Affiliation(s)
- Johnny Habchi
- Aix-Marseille Université , Architecture et Fonction des Macromolécules Biologiques (AFMB), UMR 7257, 13288, Marseille, France
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10
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Liljavirta J, Niku M, Pessa-Morikawa T, Ekman A, Iivanainen A. Expansion of the preimmune antibody repertoire by junctional diversity in Bos taurus. PLoS One 2014; 9:e99808. [PMID: 24926997 PMCID: PMC4057420 DOI: 10.1371/journal.pone.0099808] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 05/19/2014] [Indexed: 12/15/2022] Open
Abstract
Cattle have a limited range of immunoglobulin genes which are further diversified by antigen independent somatic hypermutation in fetuses. Junctional diversity generated during somatic recombination contributes to antibody diversity but its relative significance has not been comprehensively studied. We have investigated the importance of terminal deoxynucleotidyl transferase (TdT) -mediated junctional diversity to the bovine immunoglobulin repertoire. We also searched for new bovine heavy chain diversity (IGHD) genes as the information of the germline sequences is essential to define the junctional boundaries between gene segments. New heavy chain variable genes (IGHV) were explored to address the gene usage in the fetal recombinations. Our bioinformatics search revealed five new IGHD genes, which included the longest IGHD reported so far, 154 bp. By genomic sequencing we found 26 new IGHV sequences that represent potentially new IGHV genes or allelic variants. Sequence analysis of immunoglobulin heavy chain cDNA libraries of fetal bone marrow, ileum and spleen showed 0 to 36 nontemplated N-nucleotide additions between variable, diversity and joining genes. A maximum of 8 N nucleotides were also identified in the light chains. The junctional base profile was biased towards A and T nucleotide additions (64% in heavy chain VD, 52% in heavy chain DJ and 61% in light chain VJ junctions) in contrast to the high G/C content which is usually observed in mice. Sequence analysis also revealed extensive exonuclease activity, providing additional diversity. B-lymphocyte specific TdT expression was detected in bovine fetal bone marrow by reverse transcription-qPCR and immunofluorescence. These results suggest that TdT-mediated junctional diversity and exonuclease activity contribute significantly to the size of the cattle preimmune antibody repertoire already in the fetal period.
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Affiliation(s)
- Jenni Liljavirta
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
| | - Mikael Niku
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
| | | | - Anna Ekman
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
| | - Antti Iivanainen
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- * E-mail:
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11
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Malaney P, Uversky VN, Davé V. The PTEN Long N-tail is intrinsically disordered: increased viability for PTEN therapy. MOLECULAR BIOSYSTEMS 2014; 9:2877-88. [PMID: 24056727 DOI: 10.1039/c3mb70267g] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aberrant activation of the PI3K/Akt/mTOR pathway is observed in several cancers and hyper proliferative disorders. PTEN, a tumor suppressor gene, negatively regulates the PI3K/Akt/mTOR pathway. Inhibitors of various components of this pathway are currently being used for cancer therapy. However, the use of these small molecule inhibitors remains limited due to the presence of compensatory feedback loops within the pathway such that inhibition of one oncogenic molecule often results in the activation of another oncogenic molecule resulting in the development of chemoresistance. One novel strategy that has emerged as a means to circumvent the problem of feedback signaling is by activating tumor suppressor genes that abrogate oncogenic pathways and regress tumor growth. In this regard, a newly identified isoform of the PTEN protein shows promise for use in tumors with elevated PI3K/Akt/mTOR signaling. This isoform is a translational variant of PTEN, termed as PTEN Long, and has additional 173 amino acids at its N-terminus (N-173) than normal PTEN. The N-173 region is required for PTEN secretion and transport across the body. Given the potential of this N-173 region to act as a drug delivery system for PTEN, we herein analyze the structural properties of this region. This N-173 tail has a large intrinsically disordered region (IDR) and is composed of highly charged basic residues. Further, the region is enriched in potential linear binding motifs, protein-binding sites and post-translational modifications (PTMs) indicating its probable role in PTEN function and transport across cells. An extensive analysis of this region is warranted to better exploit its structural and biophysical peculiarities to drug discovery and drug delivery applications.
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Affiliation(s)
- Prerna Malaney
- Morsani College of Medicine, MDC 64, Department of Pathology and Cell Biology, University of South Florida, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA.
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12
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Berdis AJ. DNA Polymerases That Perform Template-Independent DNA Synthesis. NUCLEIC ACID POLYMERASES 2014. [DOI: 10.1007/978-3-642-39796-7_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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13
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Wernicke CM, Richter GHS, Beinvogl BC, Plehm S, Schlitter AM, Bandapalli OR, Prazeres da Costa O, Hattenhorst UE, Volkmer I, Staege MS, Esposito I, Burdach S, Grunewald TGP. MondoA is highly overexpressed in acute lymphoblastic leukemia cells and modulates their metabolism, differentiation and survival. Leuk Res 2012; 36:1185-92. [PMID: 22748921 DOI: 10.1016/j.leukres.2012.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/17/2012] [Accepted: 05/21/2012] [Indexed: 01/28/2023]
Abstract
Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. To identify novel candidates for targeted therapy, we performed a comprehensive transcriptome analysis identifying MondoA (MLXIP) - a transcription factor regulating glycolysis - to be overexpressed in ALL compared to normal tissues. Using microarray-profiling, gene-set enrichment analysis, RNA interference and functional assays we show that MondoA overexpression increases glucose catabolism and maintains a more immature phenotype, which is associated with enhanced survival and clonogenicity of leukemia cells. These data point to an important contribution of MondoA to leukemia aggressiveness and make MondoA a potential candidate for targeted treatment of ALL.
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Affiliation(s)
- Caroline M Wernicke
- Children's Cancer Research and Roman Herzog Comprehensive Cancer Center, Laboratory of Functional Genomics and Transplantation Biology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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14
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Uversky VN, Dunker AK. Understanding protein non-folding. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1804:1231-64. [PMID: 20117254 PMCID: PMC2882790 DOI: 10.1016/j.bbapap.2010.01.017] [Citation(s) in RCA: 901] [Impact Index Per Article: 64.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Revised: 01/09/2010] [Accepted: 01/21/2010] [Indexed: 02/07/2023]
Abstract
This review describes the family of intrinsically disordered proteins, members of which fail to form rigid 3-D structures under physiological conditions, either along their entire lengths or only in localized regions. Instead, these intriguing proteins/regions exist as dynamic ensembles within which atom positions and backbone Ramachandran angles exhibit extreme temporal fluctuations without specific equilibrium values. Many of these intrinsically disordered proteins are known to carry out important biological functions which, in fact, depend on the absence of a specific 3-D structure. The existence of such proteins does not fit the prevailing structure-function paradigm, which states that a unique 3-D structure is a prerequisite to function. Thus, the protein structure-function paradigm has to be expanded to include intrinsically disordered proteins and alternative relationships among protein sequence, structure, and function. This shift in the paradigm represents a major breakthrough for biochemistry, biophysics and molecular biology, as it opens new levels of understanding with regard to the complex life of proteins. This review will try to answer the following questions: how were intrinsically disordered proteins discovered? Why don't these proteins fold? What is so special about intrinsic disorder? What are the functional advantages of disordered proteins/regions? What is the functional repertoire of these proteins? What are the relationships between intrinsically disordered proteins and human diseases?
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Affiliation(s)
- Vladimir N Uversky
- Institute for Intrinsically Disordered Protein Research, Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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15
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Mahmoud TI, Kearney JF. Terminal deoxynucleotidyl transferase is required for an optimal response to the polysaccharide α-1,3 dextran. THE JOURNAL OF IMMUNOLOGY 2009; 184:851-8. [PMID: 20018621 DOI: 10.4049/jimmunol.0902791] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
An understanding of Ab responses to polysaccharides associated with pathogenic microorganisms is of importance for improving vaccine design, especially in neonates that respond poorly to these types of Ags. In this study, we have investigated the role of the lymphoid-specific enzyme TdT in generating B cell clones responsive to alpha-1,3 dextran (DEX). TdT is a DNA polymerase that plays a major role in generating diversity of lymphocyte AgRs during V(D)J recombination. In this study, we show that the DEX-specific Ab response is lower, and the dominant DEX-specific J558 idiotype (Id) is not detected in TdT(-/-) mice when compared with wild-type (WT) BALB/c mice. Nucleotide sequencing of H chain CDR3s of DEX-specific plasmablasts, sorted postimmunization, showed that TdT(-/-) mice generate a lower frequency of the predominant adult molecularly determined clone J558. Complementation of TdT expression in TdT(-/-) mice by early forced expression of the short splice variant of TdT-restored WT proportions of J558 Id+ clones and also abrogated the development of the minor M104E Id+ clones. J558 Id V(D)J rearrangements are detected as early as 7 d after birth in IgM-negative B cell precursors in the liver and spleen of WT and TdT-transgenic mice but not in TdT(-/-) mice. These data show that TdT is essential for the generation of the predominant higher-affinity DEX-responsive J558 clone.
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Affiliation(s)
- Tamer I Mahmoud
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Motea EA, Berdis AJ. Terminal deoxynucleotidyl transferase: the story of a misguided DNA polymerase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:1151-66. [PMID: 19596089 DOI: 10.1016/j.bbapap.2009.06.030] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Revised: 06/27/2009] [Accepted: 06/30/2009] [Indexed: 01/06/2023]
Abstract
Nearly every DNA polymerase characterized to date exclusively catalyzes the incorporation of mononucleotides into a growing primer using a DNA or RNA template as a guide to direct each incorporation event. There is, however, one unique DNA polymerase designated terminal deoxynucleotidyl transferase that performs DNA synthesis using only single-stranded DNA as the nucleic acid substrate. In this chapter, we review the biological role of this enigmatic DNA polymerase and the biochemical mechanism for its ability to perform DNA synthesis in the absence of a templating strand. We compare and contrast the molecular events for template-independent DNA synthesis catalyzed by terminal deoxynucleotidyl transferase with other well-characterized DNA polymerases that perform template-dependent synthesis. This includes a quantitative inspection of how terminal deoxynucleotidyl transferase binds DNA and dNTP substrates, the possible involvement of a conformational change that precedes phosphoryl transfer, and kinetic steps that are associated with the release of products. These enzymatic steps are discussed within the context of the available structures of terminal deoxynucleotidyl transferase in the presence of DNA or nucleotide substrate. In addition, we discuss the ability of proteins involved in replication and recombination to regulate the activity of the terminal deoxynucleotidyl transferase. Finally, the biomedical role of this specialized DNA polymerase is discussed focusing on its involvement in cancer development and its use in biomedical applications such as labeling DNA for detecting apoptosis.
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Affiliation(s)
- Edward A Motea
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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17
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Dunker AK, Oldfield CJ, Meng J, Romero P, Yang JY, Chen JW, Vacic V, Obradovic Z, Uversky VN. The unfoldomics decade: an update on intrinsically disordered proteins. BMC Genomics 2008; 9 Suppl 2:S1. [PMID: 18831774 PMCID: PMC2559873 DOI: 10.1186/1471-2164-9-s2-s1] [Citation(s) in RCA: 386] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Our first predictor of protein disorder was published just over a decade ago in the Proceedings of the IEEE International Conference on Neural Networks (Romero P, Obradovic Z, Kissinger C, Villafranca JE, Dunker AK (1997) Identifying disordered regions in proteins from amino acid sequence. Proceedings of the IEEE International Conference on Neural Networks, 1: 90-95). By now more than twenty other laboratory groups have joined the efforts to improve the prediction of protein disorder. While the various prediction methodologies used for protein intrinsic disorder resemble those methodologies used for secondary structure prediction, the two types of structures are entirely different. For example, the two structural classes have very different dynamic properties, with the irregular secondary structure class being much less mobile than the disorder class. The prediction of secondary structure has been useful. On the other hand, the prediction of intrinsic disorder has been revolutionary, leading to major modifications of the more than 100 year-old views relating protein structure and function. Experimentalists have been providing evidence over many decades that some proteins lack fixed structure or are disordered (or unfolded) under physiological conditions. In addition, experimentalists are also showing that, for many proteins, their functions depend on the unstructured rather than structured state; such results are in marked contrast to the greater than hundred year old views such as the lock and key hypothesis. Despite extensive data on many important examples, including disease-associated proteins, the importance of disorder for protein function has been largely ignored. Indeed, to our knowledge, current biochemistry books don't present even one acknowledged example of a disorder-dependent function, even though some reports of disorder-dependent functions are more than 50 years old. The results from genome-wide predictions of intrinsic disorder and the results from other bioinformatics studies of intrinsic disorder are demanding attention for these proteins. RESULTS Disorder prediction has been important for showing that the relatively few experimentally characterized examples are members of a very large collection of related disordered proteins that are wide-spread over all three domains of life. Many significant biological functions are now known to depend directly on, or are importantly associated with, the unfolded or partially folded state. Here our goal is to review the key discoveries and to weave these discoveries together to support novel approaches for understanding sequence-function relationships. CONCLUSION Intrinsically disordered protein is common across the three domains of life, but especially common among the eukaryotic proteomes. Signaling sequences and sites of posttranslational modifications are frequently, or very likely most often, located within regions of intrinsic disorder. Disorder-to-order transitions are coupled with the adoption of different structures with different partners. Also, the flexibility of intrinsic disorder helps different disordered regions to bind to a common binding site on a common partner. Such capacity for binding diversity plays important roles in both protein-protein interaction networks and likely also in gene regulation networks. Such disorder-based signaling is further modulated in multicellular eukaryotes by alternative splicing, for which such splicing events map to regions of disorder much more often than to regions of structure. Associating alternative splicing with disorder rather than structure alleviates theoretical and experimentally observed problems associated with the folding of different length, isomeric amino acid sequences. The combination of disorder and alternative splicing is proposed to provide a mechanism for easily "trying out" different signaling pathways, thereby providing the mechanism for generating signaling diversity and enabling the evolution of cell differentiation and multicellularity. Finally, several recent small molecules of interest as potential drugs have been shown to act by blocking protein-protein interactions based on intrinsic disorder of one of the partners. Study of these examples has led to a new approach for drug discovery, and bioinformatics analysis of the human proteome suggests that various disease-associated proteins are very rich in such disorder-based drug discovery targets.
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Affiliation(s)
- A Keith Dunker
- Center for Computational Biology and Bioinformatics, Indiana University Schools of Medicine and Informatics, Indianapolis, IN 46202, USA
| | - Christopher J Oldfield
- Center for Computational Biology and Bioinformatics, Indiana University School of Informatics, Indianapolis, IN 46202, USA
| | - Jingwei Meng
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Pedro Romero
- Center for Computational Biology and Bioinformatics, Indiana University School of Informatics, Indianapolis, IN 46202, USA
| | - Jack Y Yang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Jessica Walton Chen
- Center for Computational Biology and Bioinformatics, Indiana University School of Informatics, Indianapolis, IN 46202, USA
| | - Vladimir Vacic
- Center for Computational Biology and Bioinformatics, Indiana University School of Informatics, Indianapolis, IN 46202, USA
| | - Zoran Obradovic
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122, USA
| | - Vladimir N Uversky
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Institute for Intrinsically Disordered Protein Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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18
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Dunker AK, Oldfield CJ, Meng J, Romero P, Yang JY, Chen JW, Vacic V, Obradovic Z, Uversky VN. The unfoldomics decade: an update on intrinsically disordered proteins. BMC Genomics 2008. [PMID: 18831774 DOI: 10.1186/1471‐2164‐9‐s2‐s1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Our first predictor of protein disorder was published just over a decade ago in the Proceedings of the IEEE International Conference on Neural Networks (Romero P, Obradovic Z, Kissinger C, Villafranca JE, Dunker AK (1997) Identifying disordered regions in proteins from amino acid sequence. Proceedings of the IEEE International Conference on Neural Networks, 1: 90-95). By now more than twenty other laboratory groups have joined the efforts to improve the prediction of protein disorder. While the various prediction methodologies used for protein intrinsic disorder resemble those methodologies used for secondary structure prediction, the two types of structures are entirely different. For example, the two structural classes have very different dynamic properties, with the irregular secondary structure class being much less mobile than the disorder class. The prediction of secondary structure has been useful. On the other hand, the prediction of intrinsic disorder has been revolutionary, leading to major modifications of the more than 100 year-old views relating protein structure and function. Experimentalists have been providing evidence over many decades that some proteins lack fixed structure or are disordered (or unfolded) under physiological conditions. In addition, experimentalists are also showing that, for many proteins, their functions depend on the unstructured rather than structured state; such results are in marked contrast to the greater than hundred year old views such as the lock and key hypothesis. Despite extensive data on many important examples, including disease-associated proteins, the importance of disorder for protein function has been largely ignored. Indeed, to our knowledge, current biochemistry books don't present even one acknowledged example of a disorder-dependent function, even though some reports of disorder-dependent functions are more than 50 years old. The results from genome-wide predictions of intrinsic disorder and the results from other bioinformatics studies of intrinsic disorder are demanding attention for these proteins. RESULTS Disorder prediction has been important for showing that the relatively few experimentally characterized examples are members of a very large collection of related disordered proteins that are wide-spread over all three domains of life. Many significant biological functions are now known to depend directly on, or are importantly associated with, the unfolded or partially folded state. Here our goal is to review the key discoveries and to weave these discoveries together to support novel approaches for understanding sequence-function relationships. CONCLUSION Intrinsically disordered protein is common across the three domains of life, but especially common among the eukaryotic proteomes. Signaling sequences and sites of posttranslational modifications are frequently, or very likely most often, located within regions of intrinsic disorder. Disorder-to-order transitions are coupled with the adoption of different structures with different partners. Also, the flexibility of intrinsic disorder helps different disordered regions to bind to a common binding site on a common partner. Such capacity for binding diversity plays important roles in both protein-protein interaction networks and likely also in gene regulation networks. Such disorder-based signaling is further modulated in multicellular eukaryotes by alternative splicing, for which such splicing events map to regions of disorder much more often than to regions of structure. Associating alternative splicing with disorder rather than structure alleviates theoretical and experimentally observed problems associated with the folding of different length, isomeric amino acid sequences. The combination of disorder and alternative splicing is proposed to provide a mechanism for easily "trying out" different signaling pathways, thereby providing the mechanism for generating signaling diversity and enabling the evolution of cell differentiation and multicellularity. Finally, several recent small molecules of interest as potential drugs have been shown to act by blocking protein-protein interactions based on intrinsic disorder of one of the partners. Study of these examples has led to a new approach for drug discovery, and bioinformatics analysis of the human proteome suggests that various disease-associated proteins are very rich in such disorder-based drug discovery targets.
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Affiliation(s)
- A Keith Dunker
- Center for Computational Biology and Bioinformatics, Indiana University Schools of Medicine and Informatics, Indianapolis, IN 46202, USA.
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Maezawa S, Hayano T, Koiwai K, Fukushima R, Kouda K, Kubota T, Koiwai O. Bood POZ containing gene type 2 is a human counterpart of yeast Btb3p and promotes the degradation of terminal deoxynucleotidyltransferase. Genes Cells 2008; 13:439-57. [PMID: 18429817 DOI: 10.1111/j.1365-2443.2008.01179.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bood POZ containing gene type 2 (BPOZ-2) is involved in the growth suppressive effect of the phosphatase and tensin homologue (PTEN). We showed that BPOZ-2 is a human counterpart of yeast Btb3p, which is a putative adaptor for Pcu3p-based ubiquitin ligase. BPOZ-2 bound to E3 ligase CUL3 in vitro and in vivo. BPOZ-2 itself was ubiquitinated through the CUL3-based E3 ligase mainly within the nucleus and degraded by the 26S proteasome. Although BPOZ-2 was mainly expressed within the cytoplasm, it accumulated within the nucleus in the presence of the specific 26S proteasome inhibitor MG132. BPOZ-2 may be recruited to the nucleus from the cytoplasm. Terminal deoxynucleotidyltransferase (TdT) was detected as a BPOZ-2-binding protein using a yeast two-hybrid system by screening a human thymus cDNA library. TdT, BPOZ-2, and CUL3 formed a ternary complex in vivo. TdT was ubiquitinated only within the nucleus and degraded by the 26S proteasome. The ubiqutination or degradation of TdT was markedly promoted by co-expression of BPOZ-2 and CUL3 or BPOZ-2 in 293T cells, respectively.
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Affiliation(s)
- So Maezawa
- Faculty of Science and Technology, Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
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20
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Fowler JD, Suo Z. Biochemical, structural, and physiological characterization of terminal deoxynucleotidyl transferase. Chem Rev 2007; 106:2092-110. [PMID: 16771444 DOI: 10.1021/cr040445w] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason D Fowler
- Department of Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
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Murray JM, O’Neill JP, Messier T, Rivers J, Walker VE, McGonagle B, Trombley L, Cowell LG, Kelsoe G, McBlane F, Finette BA. V(D)J recombinase-mediated processing of coding junctions at cryptic recombination signal sequences in peripheral T cells during human development. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2006; 177:5393-404. [PMID: 17015725 PMCID: PMC1937029 DOI: 10.4049/jimmunol.177.8.5393] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
V(D)J recombinase mediates rearrangements at immune loci and cryptic recombination signal sequences (cRSS), resulting in a variety of genomic rearrangements in normal lymphocytes and leukemic cells from children and adults. The frequency at which these rearrangements occur and their potential pathologic consequences are developmentally dependent. To gain insight into V(D)J recombinase-mediated events during human development, we investigated 265 coding junctions associated with cRSS sites at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus in peripheral T cells from 111 children during the late stages of fetal development through early adolescence. We observed a number of specific V(D)J recombinase processing features that were both age and gender dependent. In particular, TdT-mediated nucleotide insertions varied depending on age and gender, including percentage of coding junctions containing N-nucleotide inserts, predominance of GC nucleotides, and presence of inverted repeats (Pr-nucleotides) at processed coding ends. In addition, the extent of exonucleolytic processing of coding ends was inversely related to age. We also observed a coding-partner-dependent difference in exonucleolytic processing and an age-specific difference in the subtypes of V(D)J-mediated events. We investigated these age- and gender-specific differences with recombination signal information content analysis of the cRSS sites in the human HPRT locus to gain insight into the mechanisms mediating these developmentally specific V(D)J recombinase-mediated rearrangements in humans.
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Affiliation(s)
- Janet M. Murray
- Department of Pediatrics, University of Vermont, Burlington, VT 05405
| | - J. Patrick O’Neill
- Department of Pediatrics, University of Vermont, Burlington, VT 05405
- Vermont Cancer Center, University of Vermont, Burlington, VT 05405
| | - Terri Messier
- Department of Pediatrics, University of Vermont, Burlington, VT 05405
- Vermont Cancer Center, University of Vermont, Burlington, VT 05405
| | - Jami Rivers
- Department of Pediatrics, University of Vermont, Burlington, VT 05405
- Vermont Cancer Center, University of Vermont, Burlington, VT 05405
| | | | | | - Lucy Trombley
- Vermont Cancer Center, University of Vermont, Burlington, VT 05405
| | - Lindsay G. Cowell
- Division of Computational Biology, Department of Biostatistics and Bioinformatics, and
| | - Garnett Kelsoe
- Department of Immunology, Duke University Medical Center, Durham, NC 27710
| | - Fraser McBlane
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Barry A. Finette
- Department of Pediatrics, University of Vermont, Burlington, VT 05405
- Vermont Cancer Center, University of Vermont, Burlington, VT 05405
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405
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Bertocci B, De Smet A, Weill JC, Reynaud CA. Nonoverlapping functions of DNA polymerases mu, lambda, and terminal deoxynucleotidyltransferase during immunoglobulin V(D)J recombination in vivo. Immunity 2006; 25:31-41. [PMID: 16860755 DOI: 10.1016/j.immuni.2006.04.013] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 03/31/2006] [Accepted: 04/10/2006] [Indexed: 11/28/2022]
Abstract
DNA polymerases mu (pol mu), lambda (pol lambda), and terminal deoxynucleotidyltransferase (TdT) are enzymes of the pol X family that share homology in sequence and functional domain organization. We showed previously that pol mu participates in light chain but surprisingly not heavy chain gene rearrangement. We show here that immunoglobulin heavy chain junctions from pol lambda-deficient animals have shorter length with normal N-additions, thus indicating that pol lambda is recruited during heavy chain rearrangement at a step that precedes the action of TdT. In contrast to previous in vitro studies, analysis of animals with combined inactivation of these enzymes revealed no overlapping or compensatory activities for V(D)J recombination between pol mu, pol lambda, and TdT. This complex usage of polymerases with distinct catalytic specificities may correspond to the specific function that the third hypervariable region assumes for each immunoglobulin chain, with pol lambda maintaining a large heavy chain junctional heterogeneity and pol mu ensuring a restricted light chain junctional variability.
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Affiliation(s)
- Barbara Bertocci
- INSERM U783, Faculté de Médecine René Descartes, Site Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France
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Wang P, Yan B, Guo JT, Hicks C, Xu Y. Structural genomics analysis of alternative splicing and application to isoform structure modeling. Proc Natl Acad Sci U S A 2005; 102:18920-5. [PMID: 16354838 PMCID: PMC1323168 DOI: 10.1073/pnas.0506770102] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alternative splicing is a sophisticated nuclear process that regulates gene expression. It represents an important mechanism for enhancing the functional diversity of proteins. Our current knowledge of alternatively spliced variants is derived mainly from mRNA transcripts, and very little is known about their protein tertiary structures. We carried out a large-scale analysis of known alternatively spliced variants at both protein sequence and structure levels and have shown that threading is, in general, a viable approach for modeling structures of alternatively spliced variants. An examination of alternative splicing at the protein sequence level revealed that the size of splicing events follows the power law distribution and the majority of splicing isoforms harbor only one or two alternations. We examined alternative splicing in the context of protein 3D structures and found that the boundaries of alternative splicing events generally happen in coil regions of secondary structures and exposed residues and the majority of the sequences involved in splicing are located on the surface of proteins. In light of these findings, we then proceeded to demonstrate that threading represents a useful tool for structure prediction of alternative splicing isoforms and addressed the fold stability issue of threading-based structure prediction by molecular dynamics simulation. Our analysis and the insights gained have helped to establish a viable method for structure prediction of alternatively spliced isoforms at the genome scale.
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Affiliation(s)
- Peng Wang
- Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, University of Georgia, Athens, GA 30622, USA
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Thai TH, Kearney JF. Isoforms of terminal deoxynucleotidyltransferase: developmental aspects and function. Adv Immunol 2005; 86:113-36. [PMID: 15705420 DOI: 10.1016/s0065-2776(04)86003-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The immune system develops in a series of programmed developmental stages. Although recombination-activating gene (RAG) and nonhomologous end-joining (NHEJ) proteins are indispensable in the generation of immunoglobulins and T-cell receptors (TCRs), most CDR3 diversity is contributed by nontemplated addition of nucleotides catalyzed by the nuclear enzyme terminal deoxynucleotidyltransferase (TdT) and most nucleotide deletion is performed by exonucleases at V(D)J joins. Increasing TdT expression continuing into adult life results in N region addition and diversification of the T and B cell repertoires. In several species including mice and humans, there are multiple isoforms of TdT resulting from alternative mRNA splicing. The short form (TdTS) produces N additions during TCR and B-cell receptor (BCR) gene rearrangements. Other long isoforms, TdTL1 and TdTL2, have 3' --> 5' exonuclease activity. The two forms of TdT therefore have distinct and opposite functions in lymphocyte development. The enzymatic activities of the splice variants of TdT play an essential role in the diversification of lymphocyte repertoires by modifying the composition and length of the gene segments involved in the production of antibodies and T-cell receptors.
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Affiliation(s)
- To-Ha Thai
- Division of Developmental and Clinical Immunology, Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35204, USA
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