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Sharma A, Liu X, Hadley D, Hagopian W, Chen WM, Onengut-Gumuscu S, Törn C, Steck AK, Frohnert BI, Rewers M, Ziegler AG, Lernmark Å, Toppari J, Krischer JP, Akolkar B, Rich SS, She JX. Identification of non-HLA genes associated with development of islet autoimmunity and type 1 diabetes in the prospective TEDDY cohort. J Autoimmun 2018; 89:90-100. [PMID: 29310926 PMCID: PMC5902429 DOI: 10.1016/j.jaut.2017.12.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 12/05/2017] [Accepted: 12/06/2017] [Indexed: 12/28/2022]
Abstract
Traditional linkage analysis and genome-wide association studies have identified HLA and a number of non-HLA genes as genetic factors for islet autoimmunity (IA) and type 1 diabetes (T1D). However, the relative risk associated with previously identified non-HLA genes is usually very small as measured in cases/controls from mixed populations. Genetic associations for IA and T1D may be more accurately assessed in prospective cohorts. In this study, 5806 subjects from the TEDDY (The Environmental Determinants of Diabetes in the Young) study, an international prospective cohort study, were genotyped for 176,586 SNPs on the ImmunoChip. Cox proportional hazards analyses were performed to discover the SNPs associated with the risk for IA, T1D, or both. Three regions were associated with the risk of developing any persistent confirmed islet autoantibody: one known region near SH2B3 (HR = 1.35, p = 3.58 × 10-7) with Bonferroni-corrected significance and another known region near PTPN22 (HR = 1.46, p = 2.17 × 10-6) and one novel region near PPIL2 (HR = 2.47, p = 9.64 × 10-7) with suggestive evidence (p < 10-5). Two known regions (PTPN22: p = 2.25 × 10-6, INS; p = 1.32 × 10-7) and one novel region (PXK/PDHB: p = 8.99 × 10-6) were associated with the risk for multiple islet autoantibodies. First appearing islet autoantibodies differ with respect to association. Two regions (INS: p = 5.67 × 10-6 and TTC34/PRDM16: 6.45 × 10-6) were associated if the fist appearing autoantibody was IAA and one region (RBFOX1: p = 8.02 × 10-6) was associated if the first appearing autoantibody was GADA. The analysis of T1D identified one region already known to be associated with T1D (INS: p = 3.13 × 10-7) and three novel regions (RNASET2, PLEKHA1, and PPIL2; 5.42 × 10-6 > p > 2.31 × 10-6). These results suggest that a number of low frequency variants influence the risk of developing IA and/or T1D and these variants can be identified by large prospective cohort studies using a survival analysis approach.
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Affiliation(s)
- Ashok Sharma
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA; Division of Biostatistics and Data Science, Department of Population Health Sciences, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Xiang Liu
- Health Informatics Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - David Hadley
- Division of Population Health Sciences and Education, St George's University of London, London, United Kingdom
| | | | - Wei-Min Chen
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
| | - Suna Onengut-Gumuscu
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
| | - Carina Törn
- Department of Clinical Sciences, Lund University/CRC, Malmö, Sweden
| | - Andrea K Steck
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Denver, Aurora, CO, USA
| | - Brigitte I Frohnert
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Denver, Aurora, CO, USA
| | - Marian Rewers
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Denver, Aurora, CO, USA
| | - Anette-G Ziegler
- Institute of Diabetes Research, Helmholtz Zentrum München, Munich-Neuherberg, Germany; Klinikum rechts der Isar, Technische Universität München, Munich-Neuherberg, Germany; Forschergruppe Diabetes e.V., Munich-Neuherberg, Germany
| | - Åke Lernmark
- Department of Clinical Sciences, Lund University/CRC, Malmö, Sweden
| | - Jorma Toppari
- Department of Pediatrics, Turku University Hospital, Turku, Finland
| | - Jeffrey P Krischer
- Health Informatics Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Beena Akolkar
- National Institutes of Diabetes and Digestive and Kidney Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Stephen S Rich
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
| | - Jin-Xiong She
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA.
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Jia Z, Wang M, Li S, Li X, Bai XY, Xu Z, Yang Y, Li B, Li Y, Wu H. U-box ubiquitin ligase PPIL2 suppresses breast cancer invasion and metastasis by altering cell morphology and promoting SNAI1 ubiquitination and degradation. Cell Death Dis 2018; 9:63. [PMID: 29352246 PMCID: PMC5833831 DOI: 10.1038/s41419-017-0094-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/17/2017] [Accepted: 10/24/2017] [Indexed: 01/30/2023]
Abstract
Metastasis is the leading cause of breast cancer fatalities. To develop new therapeutic strategies, the mechanisms underlying breast cancer invasion and metastasis need to be further investigated. Peptidylprolyl isomerase (cyclophilin)-like 2 (PPIL2) is a U-box-type E3 ubiquitin ligase belonging to the cyclophilin family. Proteins within this family are the major cytosolic binding proteins of the immunosuppressant drug cyclosporine A (CsA). Although PPIL2 has been reported to potentially be involved in cell migration, its role in breast cancer is still unclear. Herein, we demonstrate that PPIL2 suppressed metastasis in a breast cancer model by altering cell morphology and suppressing the epithelial–mesenchymal transition (EMT) process. Moreover, elevated PPIL2 inhibited EMT and breast cancer invasion by interacting with the classical EMT transcription factor, SNAI1, to enhance its ubiquitin-dependent degradation. Furthermore, PPIL2 protein level and stability was upregulated after CsA treatment, indicating that PPIL2 might be involved in CsA-mediated repression of EMT in breast cancer. Analysis of tissue samples taken from breast cancer patients showed a significant correlation between the expression of PPIL2 and the degree of cancer invasion and metastasis. In summary, these results would shed light on a potential clinical use of CsA in breast cancer patients.
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Affiliation(s)
- Zhaojun Jia
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Miao Wang
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Shujing Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Xiahui Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Xiao-Yan Bai
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Zhaowei Xu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Yangyang Yang
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Bowen Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Yanan Li
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
| | - Huijian Wu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China.
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3
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Watashi K, Shimotohno K. Cyclophilin and Viruses: Cyclophilin as a Cofactor for Viral Infection and Possible Anti-Viral Target. Drug Target Insights 2017. [DOI: 10.1177/117739280700200017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- Koichi Watashi
- Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Kunitada Shimotohno
- Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan
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4
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Beyer N, Coulson D, Quinn J, Brockbank S, Hellemans J, Irvine G, Ravid R, Johnston J. mRNA levels of BACE1 and its interacting proteins, RTN3 and PPIL2, correlate in human post mortem brain tissue. Neuroscience 2014; 274:44-52. [DOI: 10.1016/j.neuroscience.2014.05.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 05/12/2014] [Accepted: 05/12/2014] [Indexed: 01/21/2023]
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5
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Cyclophilins as modulators of viral replication. Viruses 2013; 5:1684-701. [PMID: 23852270 PMCID: PMC3738956 DOI: 10.3390/v5071684] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 06/26/2013] [Accepted: 07/03/2013] [Indexed: 01/11/2023] Open
Abstract
Cyclophilins are peptidyl‐prolyl cis/trans isomerases important in the proper folding of certain proteins. Mounting evidence supports varied roles of cyclophilins, either positive or negative, in the life cycles of diverse viruses, but the nature and mechanisms of these roles are yet to be defined. The potential for cyclophilins to serve as a drug target for antiviral therapy is evidenced by the success of non-immunosuppressive cyclophilin inhibitors (CPIs), including Alisporivir, in clinical trials targeting hepatitis C virus infection. In addition, as cyclophilins are implicated in the predisposition to, or severity of, various diseases, the ability to specifically and effectively modulate their function will prove increasingly useful for disease intervention. In this review, we will summarize the evidence of cyclophilins as key mediators of viral infection and prospective drug targets.
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Engdahl C, Näslund J, Lindgren L, Ahlm C, Bucht G. The Rift Valley Fever virus protein NSm and putative cellular protein interactions. Virol J 2012; 9:139. [PMID: 22838834 PMCID: PMC3439357 DOI: 10.1186/1743-422x-9-139] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 07/17/2012] [Indexed: 12/19/2022] Open
Abstract
Rift Valley Fever is an infectious viral disease and an emerging problem in many countries of Africa and on the Arabian Peninsula. The causative virus is predominantly transmitted by mosquitoes and high mortality and abortion rates characterize outbreaks in animals while symptoms ranging from mild to life-threatening encephalitis and hemorrhagic fever are noticed among infected humans. For a better prevention and treatment of the infection, an increased knowledge of the infectious process of the virus is required. The focus of this work was to identify protein-protein interactions between the non-structural protein (NSm), encoded by the M-segment of the virus, and host cell proteins. This study was initiated by screening approximately 26 million cDNA clones of a mouse embryonic cDNA library for interactions with the NSm protein using a yeast two-hybrid system. We have identified nine murine proteins that interact with NSm protein of Rift Valley Fever virus, and the putative protein-protein interactions were confirmed by growth selection procedures and β-gal activity measurements. Our results suggest that the cleavage and polyadenylation specificity factor subunit 2 (Cpsf2), the peptidyl-prolyl cis-trans isomerase (cyclophilin)-like 2 protein (Ppil2), and the synaptosome-associated protein of 25 kDa (SNAP-25) are the most promising targets for the NSm protein of the virus during an infection.
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Affiliation(s)
- Cecilia Engdahl
- Department of Clinical Microbiology, Umeå University, SE-90187 Umeå, Sweden
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Trachtenberg A, Pushkarsky T, Heine S, Constant S, Brichacek B, Bukrinsky M. The level of CD147 expression correlates with cyclophilin-induced signalling and chemotaxis. BMC Res Notes 2011; 4:396. [PMID: 21989251 PMCID: PMC3198701 DOI: 10.1186/1756-0500-4-396] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 10/11/2011] [Indexed: 12/16/2022] Open
Abstract
Background Previous studies identified CD147 as the chemotactic receptor on inflammatory leukocytes for extracellular cyclophilins (eCyp). However, CD147 is not known to associate with signal transducing molecules, so other transmembrane proteins, such as proteoglycans, integrins, and CD98, were suggested as receptor or co-receptor for eCyp. CD147 is ubiquitously expressed on many cell types, but relationship between the level of CD147 expression and cellular responses to eCyp has never been analyzed. Given the role of eCyp in pathogenesis of many diseases, it is important to know whether cellular responses to eCyp are regulated at the level of CD147 expression. Results Here, we manipulated CD147 expression levels on HeLa cells using RNAi and investigated the signalling and chemotactic responses to eCypA. Both Erk activation and chemotaxis correlated with the level of CD147 expression, with cells exhibiting low level expression being practically unresponsive to eCypA. Conclusions Our results provide the first demonstration of a chemotactic response of HeLa cells to eCypA, establish a correlation between the level of CD147 expression and the magnitude of cellular responses to eCypA, and indicate that CD147 may be a limiting factor in the receptor complex determining cyclophilin-induced Erk activation and cell migration.
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8
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Abstract
Background The patterns of emergence and diversification of the families of ubiquitin ligases provide insights about the evolution of the eukaryotic ubiquitination system. U-box ubiquitin ligases (UULs) are proteins characterized by containing a peculiar protein domain known as U box. In this study, the origin of the animal UUL genes is described. Results Phylogenetic and structural data indicate that six of the seven main UUL-encoding genes found in humans (UBE4A, UBE4B, UIP5, PRP19, CHIP and CYC4) were already present in the ancestor of all current metazoans and the seventh (WDSUB1) is found in placozoans, cnidarians and bilaterians. The fact that only 4 - 5 genes orthologous to the human ones are present in the choanoflagellate Monosiga brevicollis suggests that several animal-specific cooptions of the U box to generate new genes occurred. Significantly, Monosiga contains five additional UUL genes that are not present in animals. One of them is also present in distantly-related protozoans. Along animal evolution, losses of UUL-encoding genes are rare, except in nematodes, which lack three of them. These general patterns are highly congruent with those found for other two families (RBR, HECT) of ubiquitin ligases. Conclusions Finding that the patterns of emergence, diversification and loss of three unrelated families of ubiquitin ligases (RBR, HECT and U-box) are parallel indicates that there are underlying, linage-specific evolutionary forces shaping the complexity of the animal ubiquitin system.
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Pemberton TJ, Kay JE. Identification and comparative analysis of the peptidyl-prolyl cis/trans isomerase repertoires of H. sapiens, D. melanogaster, C. elegans, S. cerevisiae and Sz. pombe. Comp Funct Genomics 2010; 6:277-300. [PMID: 18629211 PMCID: PMC2447506 DOI: 10.1002/cfg.482] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Revised: 05/01/2005] [Accepted: 05/26/2005] [Indexed: 11/11/2022] Open
Abstract
The peptidyl-prolyl cis/trans isomerase (PPIase) class of proteins comprises three
member families that are found throughout nature and are present in all the major
compartments of the cell. Their numbers appear to be linked to the number of genes in
their respective genomes, although we have found the human repertoire to be smaller
than expected due to a reduced cyclophilin repertoire. We show here that whilst the
members of the cyclophilin family (which are predominantly found in the nucleus
and cytoplasm) and the parvulin family (which are predominantly nuclear) are
largely conserved between different repertoires, the FKBPs (which are predominantly
found in the cytoplasm and endoplasmic reticulum) are not. It therefore appears
that the cyclophilins and parvulins have evolved to perform conserved functions,
while the FKBPs have evolved to fill ever-changing niches within the constantly
evolving organisms. Many orthologous subgroups within the different PPIase families
appear to have evolved from a distinct common ancestor, whereas others, such as the
mitochondrial cyclophilins, appear to have evolved independently of one another. We
have also identified a novel parvulin within Drosophila melanogaster that is unique to
the fruit fly, indicating a recent evolutionary emergence. Interestingly, the fission yeast
repertoire, which contains no unique cyclophilins and parvulins, shares no PPIases
solely with the budding yeast but it does share a majority with the higher eukaryotes
in this study, unlike the budding yeast. It therefore appears that, in comparison with
Schizosaccharomyces pombe, Saccharomyces cerevisiae is a poor representation of the
higher eukaryotes for the study of PPIases.
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Affiliation(s)
- Trevor J Pemberton
- The Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton ,East Sussex BN1 9PX, United Kingdom.
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10
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Variation in RTN3 and PPIL2 Genes Does not Influence Platelet Membrane β-Secretase Activity or Susceptibility to Alzheimer’s Disease in the Northern Irish Population. Neuromolecular Med 2009; 11:337-44. [DOI: 10.1007/s12017-009-8080-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 07/15/2009] [Indexed: 11/27/2022]
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11
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Characterization of cyclophilin-encoding genes in Phytophthora. Mol Genet Genomics 2009; 281:565-78. [PMID: 19221798 DOI: 10.1007/s00438-009-0431-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 01/30/2009] [Indexed: 10/21/2022]
Abstract
Recent research has shown that cyclophilins, proteins that catalyze the isomerization of peptidyl-prolyl bonds, play a variety of important roles in infection, including facilitating host penetration and colonization and activating pathogen effector proteins within the host cytoplasm. In the current study, bioinformatic analysis of the genomes of three species of plant pathogens in the genus Phytophthora has revealed extensive synteny between the 20 or 21 members of the cyclophilin gene family. In P. infestans, extensive EST studies give evidence of the expression of 14 of the 21 genes. Sequences homologous to 12 of the 14 expressed P. infestans cyclophilins were isolated using PCR and gene-specific primers in the broad host range pathogen, P. nicotianae. Quantitative real-time PCR measurements of transcript levels in P. nicotianae at four stages of asexual development and during infection of resistant and susceptible tobacco plants gave evidence of expression of seven of the P. nicotianae homologs. The most abundantly expressed gene, PnCyPA, has a lower mRNA level in zoospores compared to other stages of asexual development and its expression increases during infection of susceptible plants. Immunocytochemical studies indicate that PnCyPA occurs in the nucleus and cytoplasm of P. nicotianae cells and is secreted from germinated cysts.
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12
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Biochemical function of typical and variant Arabidopsis thaliana U-box E3 ubiquitin-protein ligases. Biochem J 2008; 413:447-57. [PMID: 18393940 DOI: 10.1042/bj20071568] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The variance of the U-box domain in 64 Arabidopsis thaliana (thale cress) E3s (ubiquitin-protein ligases) was used to examine the interactions between E3s and E2s (ubiquitin-conjugating enzymes). E2s and E3s are components of the ubiquitin protein degradation pathway. Seven U-box proteins were analysed for their ability to ubiquitinate proteins in vitro in co-operation with different E2s. All U-box domains exhibited ubiquitination activity and interacted productively with UBC4/5-type E2s. Three and four of the U-box domains mediated ubiquitin addition in the presence of UBC13 and UBC7 E2s respectively, but no productive interaction was observed with the UBC15 E2 tested. The activity of AtPUB54 [Arabidopsis thaliana (thale cress) plant U-box 54 protein] was dependent on Trp(266) in the E2-binding cleft, and the E2 selectivity was changed by substitution of this position. The function of the distant U-box protein, AtPUB49, representing a large family of eukaryotic proteins containing a U-box linked to a cyclophilin-like peptidyl-prolyl cis-trans isomerase domain, was characterized biochemically. AtPUB49 functioned both as a prolyl isomerase and a chaperone by catalysing cis-trans isomerization of peptidyl-prolyl bonds and dissolving protein aggregates. In conclusion, both typical and atypical Arabidopsis U-box proteins were active E3s. The overlap in the E3/E2 selectivity suggests that in vivo specificity is not determined only by the E3-E2 interactions, but also by other parameters, e.g. co-existence or interactions with additional domains. The biochemical functions of AtPUB49 suggest that the protein can be involved in folding or degradation of protein substrates. Similar functions can also be retained within a protein complex with separate chaperone and U-box proteins.
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Watashi K, Shimotohno K. Cyclophilin and viruses: cyclophilin as a cofactor for viral infection and possible anti-viral target. Drug Target Insights 2007; 2:9-18. [PMID: 21901058 PMCID: PMC3155236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Cyclophilin (CyP) is a peptidyl prolyl cis/trans isomerase, catalyzing the cis-trans isomerization of proline residues in proteins. CyP plays key roles in several different aspects of cellular physiology including the immune response, transcription, mitochondrial function, cell death, and chemotaxis. In addition to these cellular events, a number of reports demonstrated that CyP plays a critical role in the life cycle of viruses, especially human immunodeficiency virus (HIV) and hepatitis C virus (HCV). These two viruses are significant causes of morbidity and mortality worldwide, but current therapies are often insufficient. CyP may provide a novel therapeutic target for the management and/or cure of these diseases, in particular HCV.
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Affiliation(s)
- Koichi Watashi
- Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Kunitada Shimotohno
- Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan
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14
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Espeseth AS, Huang Q, Gates A, Xu M, Yu Y, Simon AJ, Shi XP, Zhang X, Hodor P, Stone DJ, Burchard J, Cavet G, Bartz S, Linsley P, Ray WJ, Hazuda D. A genome wide analysis of ubiquitin ligases in APP processing identifies a novel regulator of BACE1 mRNA levels. Mol Cell Neurosci 2006; 33:227-35. [PMID: 16978875 DOI: 10.1016/j.mcn.2006.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Accepted: 07/07/2006] [Indexed: 10/24/2022] Open
Abstract
Proteolysis of beta-amyloid precursor protein (APP) into amyloid beta peptide (Abeta) by beta- and gamma-secretases is a critical step in the pathogenesis of Alzheimer's Disease (AD), but the pathways regulating secretases are not fully characterized. Ubiquitinylation, which is dysregulated in AD, may affect APP processing. Here, we describe a screen for APP processing modulators using an siRNA library targeting 532 predicted ubiquitin ligases. Seven siRNA pools diminished Abeta production. Of these, siRNAs targeting PPIL2 (hCyp-60) suppressed beta-site cleavage. Knockdown of PPIL2 mRNA decreased BACE1 mRNA, while overexpression of PPIL2 cDNA enhanced BACE1 mRNA levels. Microarray analysis of PPIL2 or BACE1 knockdown indicated that genes affected by BACE1 knockdown are a subset of those dependent upon PPIL2; suggesting that BACE1 expression is downstream of PPIL2. The association of PPIL2 with BACE expression and its requirement for Abeta production suggests new approaches to discover disease modifying agents for AD.
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Affiliation(s)
- Amy S Espeseth
- Department of Molecular and Cellular Technologies, Merck Research Laboratories, P.O. Box 4, West Point, PA 19486, USA
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15
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Potenza M, Galat A, Minning TA, Ruiz AM, Duran R, Tarleton RL, Marín M, Fichera LE, Búa J. Analysis of the Trypanosoma cruzi cyclophilin gene family and identification of Cyclosporin A binding proteins. Parasitology 2006; 132:867-82. [PMID: 16700961 DOI: 10.1017/s0031182005009558] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 10/08/2005] [Accepted: 10/14/2005] [Indexed: 01/22/2023]
Abstract
The Trypanosoma cruzi cyclophilin gene family comprises 15 paralogues whose nominal masses vary from 19 to 110 kDa, namely TcCyP19, TcCyP20, TcCyP21, TcCyP22, TcCyP24, TcCyP25, TcCyP26, TcCyP28, TcCyP29, TcCyP30, TcCyP34, TcCyP35, TcCyP40, TcCyP42 and TcCyP110. Under the conditions used, only some of the T. cruzi cyclophilin paralogue products could be isolated by affinity chromatography. The 15 paralogues were aligned with 495 cyclophilins from diverse organisms. Analyses of clusters formed by the T. cruzi cyclophilins with others encoded in various genomes revealed that 8 of them (TcCyP19, TcCyP21, TcCyP22, TcCyP24, TcCyP35, TcCyP40, TcCyP42 and TcCyP110) have orthologues in many different genomes whereas the other 7 display less-defined patterns of their sequence attributes and their classification to a specific group of cyclophilin's orthologues remains uncertain. Seven epimastigote cDNA clones encoding cyclophilin isoforms were further studied. These genes were found dispersed throughout the genome of the parasite. Amastigote and trypomastigote mRNAs encoding these 7 genes were also detected. We isolated 4 cyclosporin A-binding proteins in T. cruzi epimastigote extracts, which were identified by mass spectrometry as TcCyP19, TcCyP22, TcCyP28 and TcCyP40. Cyclosporin A-binding to these cyclophilins might be of importance to the mechanism of action of Cyclosporin A and its non-immunosuppressive analogues, whose trypanocidal effects were previously reported, and therefore, of potential interest in the chemotherapy of Chagas' disease.
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Affiliation(s)
- M Potenza
- Instituto Nacional de Parasitología, Dr. M. Fatala Chabén, A.N.L.I.S. Malbrán, Buenos Aires, Argentina
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16
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Pemberton TJ, Kay JE. The cyclophilin repertoire of the fission yeast Schizosaccharomyces pombe. Yeast 2005; 22:927-45. [PMID: 16134115 DOI: 10.1002/yea.1288] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The cyclophilin repertoire of the fission yeast Schizosaccharomyces pombe is comprised of nine members that are distributed over all three of its chromosomes and range from small single-domain to large multi-domain proteins. Each cyclophilin possesses only a single prolyl-isomerase domain, and these vary in their degree of consensus, including at positions that are likely to affect their drug-binding ability and catalytic activity. The additional identified motifs are involved in putative protein or RNA interactions, while a novel domain that is specific to SpCyp7 and its orthologues may have functions that include an interaction with hnRNPs. The Sz. pombe cyclophilins are found throughout the cell but appear to be absent from the mitochondria, which is unique among the characterized eukaryotic repertoires. SpCyp5, SpCyp6 and SpCyp8 have exhibited significant upregulation of their expression during the meiotic cycle and SpCyp5 has exhibited significant upregulation of its expression during heat stress. All nine have identified members in the repertoires of H. sapiens, D. melanogaster and A. thaliana. However, only three identified members in the cyclophilin repertoire of S. cerevisiae with SpCyp7 identifying a fourth protein that is not a member of the recognized repertoire due to its possession of a degenerate prolyl-isomerase domain. The cyclophilin repertoire of Sz. pombe therefore represents a better model group for the study of cyclophilin function in the higher eukaryotes.
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Affiliation(s)
- Trevor J Pemberton
- The Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, East Sussex BN1 9PX, UK.
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17
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Pushkarsky T, Yurchenko V, Vanpouille C, Brichacek B, Vaisman I, Hatakeyama S, Nakayama KI, Sherry B, Bukrinsky MI. Cell surface expression of CD147/EMMPRIN is regulated by cyclophilin 60. J Biol Chem 2005; 280:27866-71. [PMID: 15946952 DOI: 10.1074/jbc.m503770200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD147, also known as extracellular matrix metalloproteinase inducer, is a regulator of matrix metalloproteinase production and also serves as a signaling receptor for extracellular cyclophilins. Previously, we demonstrated that cell surface expression of CD147 is sensitive to cyclophilin-binding drug cyclosporin A, suggesting involvement of a cyclophilin in the regulation of intracellular transport of CD147. In this report, we identify this cyclophilin as cyclophilin 60 (Cyp60), a distinct member of the cyclophilin family of proteins. CD147 co-immunoprecipitated with Cyp60, and confocal immunofluorescent microscopy revealed intracellular co-localization of Cyp60 and CD147. This interaction with Cyp60 involved proline 211 of CD147, which was shown previously to be critical for interaction between CD147 and another cyclophilin, cyclophilin A, in solution. Mutation of this proline residue abrogated co-immunoprecipitation of CD147 and Cyp60 and reduced surface expression of CD147 on the plasma membrane. Suppression of Cyp60 expression using RNA interference had an effect similar to that of cyclosporin A: reduction of cell surface expression of CD147. These results suggest that Cyp60 plays an important role in the translocation of CD147 to the cell surface. Therefore, Cyp60 may present a novel target for therapeutic interventions in diseases where CD147 functions as a pathogenic factor, such as cancer, human immunodeficiency virus infection, or rheumatoid arthritis.
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Affiliation(s)
- Tatiana Pushkarsky
- The George Washington University Medical Center, Washington, DC 20037, USA
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18
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Roest HP, Baarends WM, de Wit J, van Klaveren JW, Wassenaar E, Hoogerbrugge JW, van Cappellen WA, Hoeijmakers JHJ, Grootegoed JA. The ubiquitin-conjugating DNA repair enzyme HR6A is a maternal factor essential for early embryonic development in mice. Mol Cell Biol 2004; 24:5485-95. [PMID: 15169909 PMCID: PMC419895 DOI: 10.1128/mcb.24.12.5485-5495.2004] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 01/24/2004] [Accepted: 03/28/2004] [Indexed: 11/20/2022] Open
Abstract
The Saccharomyces cerevisiae RAD6 protein is required for a surprising diversity of cellular processes, including sporulation and replicational damage bypass of DNA lesions. In mammals, two RAD6-related genes, HR6A and HR6B, encode highly homologous proteins. Here, we describe the phenotype of cells and mice deficient for the mHR6A gene. Just like mHR6B knockout mouse embryonic fibroblasts, mHR6A-deficient cells appear to have normal DNA damage resistance properties, but mHR6A knockout male and female mice display a small decrease in body weight. The necessity for at least one functional mHR6A (X-chromosomal) or mHR6B (autosomal) allele in all somatic cell types is supported by the fact that neither animals lacking both proteins nor females with only one intact mHR6A allele are viable. In striking contrast to mHR6B knockout males, which show a severe spermatogenic defect, mHR6A knockout males are normally fertile. However, mHR6A knockout females fail to produce offspring despite a normal ovarian histology and ovulation. The absence of mHR6A in oocytes prevents development beyond the embryonic two-cell stage but does not result in an aberrant methylation pattern of histone H3 at this early stage of mouse embryonic development. These observations support redundant but dose-dependent roles for HR6A and HR6B in somatic cell types and germ line cells in mammals.
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Affiliation(s)
- Henk P Roest
- MGC-Department of Cell Biology and Genetics, Centre for Biomedical Genetics, Erasmus MC, Rotterdam, The Netherlands
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19
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Belfiore M, Pugnale P, Saudan Z, Puoti A. Roles of the C. elegans cyclophilin-like protein MOG-6 in MEP-1 binding and germline fates. Development 2004; 131:2935-45. [PMID: 15151984 DOI: 10.1242/dev.01154] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The switch from spermatogenesis to oogenesis in the Caenorhabditis elegans hermaphrodite requires mog-6, which post-transcriptionally represses the fem-3 RNA. In this study, we show that mog-6 codes for a divergent nuclear cyclophilin, in that a conserved domain is not required for its function in the sperm-oocyte switch. MOG-6 binds to the nuclear zinc finger protein MEP-1 through two separate domains that are essential for the role of MOG-6 in the sperm-oocyte switch. We propose that MOG-6 has a function distinct from that of prevailing cyclophilins and that its binding to MEP-1 is essential for germline sex determination. Finally, we found that gld-3 mog-6 mutants develop germline tumors, suggesting that mog-6 might function in the decision between mitosis and meiosis.
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Affiliation(s)
- Marco Belfiore
- Department of Biology, Unit of Zoology, University of Fribourg, 1700 Fribourg, Switzerland
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20
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Abstract
The 18 kDa archetypal cyclosporin-A binding protein, cyclophilin-A, has multiple paralogues in the human genome. Only 18 of those paralogues have been detected as mRNAs or proteins whose masses vary from 18 to 354 kDa, whereas the functional significance of the open reading frames (ORFs) encoding other paralogues of cyclophilin-A remains unknown. The genomes of Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana, Schizosaccharomyces pombe, and Saccharomyces cerevisiae encode different numbers of the cyclophilin paralogues, some of which are orthologous to the human cyclophilins. A library of novel algorithms was developed and used for computation of the conservation levels for hydrophobicity and bulkiness profiles, and amino acid compositions (AACs) of 303 aligned sequences of cyclophilins. The majority of the paralogues and orthologues encoded in these 6 genomes differ considerably from each other. Some of the orthologues and paralogues have high correlation coefficients (CCFs) for pairwise compared hydrophobicity and bulkiness profiles, and whose AACs differ to a low degree. Convergence of these three properties of the polypeptide chain and apparent conservation of the typical sequence hallmarks and parameters allowed for the clustering of the functionally related orthologues and paralogues of the cyclophilins. The clustering method allowed for sorting out the cyclophilins into several distinct classes. Analyses of the overlapping clusters of sequences permitted delineation of some hypothetical pathways that might have led to the creation of certain paralogues of cyclophilins in the eukaryotic genomes.
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Affiliation(s)
- Andrzej Galat
- Département d'Ingénierie et d'Etudes des Protéines, DSV/CEA, Gif-sur-Yvette Cedex, France.
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21
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Romano PGN, Horton P, Gray JE. The Arabidopsis cyclophilin gene family. PLANT PHYSIOLOGY 2004; 134:1268-82. [PMID: 15051864 PMCID: PMC419803 DOI: 10.1104/pp.103.022160] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2003] [Revised: 03/31/2003] [Accepted: 06/09/2003] [Indexed: 05/17/2023]
Abstract
Database searching has allowed the identification of a number of previously unreported single and multidomain isoform members of the Arabidopsis cyclophilin gene family. In addition to the cyclophilin-like peptidyl-prolyl cis-trans isomerase domain, the latter contain a variety of other domains with characterized functions. Transcriptional analysis showed they are expressed throughout the plant, and different isoforms are present in all parts of the cell including the cytosol, nucleus, mitochondria, secretory pathway, and chloroplast. The abundance and diversity of cyclophilin isoforms suggests that, like their animal counterparts, plant cyclophilins are likely to be important proteins involved in a wide variety of cellular processes. As well as fulfilling the basic role of protein folding, they may also play important roles in mRNA processing, protein degradation, and signal transduction and thus may be crucial during both development and stress responsiveness.
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Affiliation(s)
- Patrick G N Romano
- Robert Hill Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
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22
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Abstract
Ubiquitin-protein ligases (E3s) determine the substrate specificity of ubiquitylation and, until recently, had been classified into two families, the HECT and RING-finger families. The U-box is a domain of approximately 70 amino acids that is present in proteins from yeast to humans. The prototype U-box protein, yeast Ufd2, was identified as a ubiquitin chain assembly factor (E4) that cooperates with a ubiquitin-activating enzyme (E1), a ubiquitin-conjugating enzyme (E2), and an E3 to catalyze the formation of a ubiquitin chain on artificial substrates. We recently showed that mammalian U-box proteins, in conjunction with an E1 and an E2, mediate polyubiquitylation in the absence of a HECT type or RING-finger type E3. U-box proteins have thus been defined as a third family of E3s. We here review recent progress in the characterization of U-box proteins and of their role in the quality control system that underlies the cellular stress response to the intracellular accumulation of abnormal proteins.
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Affiliation(s)
- Shigetsugu Hatakeyama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan.
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23
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Kaneko C, Hatakeyama S, Matsumoto M, Yada M, Nakayama K, Nakayama KI. Characterization of the mouse gene for the U-box-type ubiquitin ligase UFD2a. Biochem Biophys Res Commun 2003; 300:297-304. [PMID: 12504083 DOI: 10.1016/s0006-291x(02)02834-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UFD2a is a mammalian homolog of Saccharomyces cerevisiae Ufd2, originally described as an E4 ubiquitination factor. UFD2a belongs to the U-box family of ubiquitin ligases (E3s) and likely functions as both an E3 and E4. We have isolated and characterized the mouse gene (Ube4b) for UFD2a. A full-length (approximately 5700 bp) Ube4b cDNA was isolated and the corresponding gene spans >100 kb, comprising 27 exons. Luciferase reporter gene analysis of the 5(') flanking region of Ube4b revealed that nucleotides -1018 to -943 (relative to the translation initiation site) possess promoter activity. This functional sequence contains two putative Sp1 binding sites but not a TATA box. Immunoblot and immunohistochemical analyses revealed that UFD2a is expressed predominantly in the neuronal tissues. We also show that UFD2a interacts with VCP (a AAA-family ATPase) that is thought to mediate protein folding. These data implicate UFD2a in the degradation of neuronal proteins by the ubiquitin-proteasome pathway.
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Affiliation(s)
- Chie Kaneko
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka, 812-8582, Japan
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24
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Patterson C. A new gun in town: the U box is a ubiquitin ligase domain. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2002; 2002:pe4. [PMID: 11805346 DOI: 10.1126/stke.2002.116.pe4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ubiquitin ligases determine protein stability in a highly regulated manner by coordinating the addition of polyubiquitin chains to proteins that are then targeted to the proteasome for degradation. Ubiquitin ligases have generally been separated into two groups--those containing HECT domains and those with RING finger domains. Recently, a third group of ubiquitin ligases has emerged: those containing a U-box domain. Patterson discusses what is known about the few U-box-containing proteins that have been characterized, although the general properties of U-box proteins that distinguish them from other ubiquitin ligases are still a matter of speculation.
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Affiliation(s)
- Cam Patterson
- Carolina Cardiovascular Biology Center, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599-7126, USA.
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Hatakeyama S, Yada M, Matsumoto M, Ishida N, Nakayama KI. U box proteins as a new family of ubiquitin-protein ligases. J Biol Chem 2001; 276:33111-20. [PMID: 11435423 DOI: 10.1074/jbc.m102755200] [Citation(s) in RCA: 422] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The U box is a domain of approximately 70 amino acids that is present in proteins from yeast to humans. The prototype U box protein, yeast Ufd2, was identified as a ubiquitin chain assembly factor that cooperates with a ubiquitin-activating enzyme (E1), a ubiquitin-conjugating enzyme (E2), and a ubiquitin-protein ligase (E3) to catalyze ubiquitin chain formation on artificial substrates. E3 enzymes are thought to determine the substrate specificity of ubiquitination and have been classified into two families, the HECT and RING finger families. Six mammalian U box proteins have now been shown to mediate polyubiquitination in the presence of E1 and E2 and in the absence of E3. These U box proteins exhibited different specificities for E2 enzymes in this reaction. Deletion of the U box or mutation of conserved amino acids within it abolished ubiquitination activity. Some U box proteins catalyzed polyubiquitination by targeting lysine residues of ubiquitin other than lysine 48, which is utilized by HECT and RING finger E3 enzymes for polyubiquitination that serves as a signal for proteolysis by the 26 S proteasome. These data suggest that U box proteins constitute a third family of E3 enzymes and that E4 activity may reflect a specialized type of E3 activity.
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Affiliation(s)
- S Hatakeyama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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26
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Colgan J, Asmal M, Luban J. Isolation, characterization and targeted disruption of mouse ppia: cyclophilin A is not essential for mammalian cell viability. Genomics 2000; 68:167-78. [PMID: 10964515 DOI: 10.1006/geno.2000.6295] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cyclophilins (CyPs) are a family of proteins found in organisms ranging from prokaryotes to humans. These molecules exhibit peptidyl-prolyl isomerase activity in vitro, suggesting that they influence the conformation of proteins in cells. CyPs also bind with varying affinities to the immunosuppressive drug cyclosporin A (CsA), a compound used clinically to prevent allograft rejection. The founding member of the family, cyclophilin A (CyPA), is an abundant, ubiquitously expressed protein of unknown function that binds with nanomolar affinity to CsA. Here, we describe the isolation and characterization of mouse Ppia (mPpia), the gene encoding CyPA. Ppia was isolated using a PCR screen that distinguishes the expressed gene from multiple pseudogenes present in the mouse genome. mPpia consists of 5 exons and 4 introns spanning roughly 4.5 kb and maps to chromosome 11 near the centromere. Sequence analysis of a 369-bp fragment from the proximal promoter region of mPpia revealed the presence of a TATA box and sites recognized by several transcriptional regulators, including Sp1, AP-2, GATA factors, c-Myb, and NF-IL-6. This region is sufficient to drive high-level reporter gene expression in transfected cells. Both copies of Ppia were disrupted in murine embryonic stem (ES) cells via gene targeting. Ppia(-/-) ES cells grow normally and differentiate into hematopoeitic precursor cells in vitro, indicating that CyPA is not essential for mammalian cell viability.
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Affiliation(s)
- J Colgan
- Department of Microbiology, Department of Medicine, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, New York, 10032, USA
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27
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Galat A. Variations of sequences and amino acid compositions of proteins that sustain their biological functions: An analysis of the cyclophilin family of proteins. Arch Biochem Biophys 1999; 371:149-62. [PMID: 10545201 DOI: 10.1006/abbi.1999.1434] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The sequences of the ubiquitous and phylogenetically diversified cyclophilin family of proteins were divided into six groups, namely, vertebrates, invertebrates, other metazoa, plants, fungi, and prokaryotes. These groups of sequences were aligned with the multiple sequence alignment program Clustal-W. The variations of amino acid substitutions and amino acid compositions for these six groups of cyclophilins were calculated using a novel suite of multiple-sequence alignment analysis routines. The cyclophilins from vertebrates can be divided for at least two distinct structural classes that differ from each other by a variable-length amino acid insert within the loop that links alpha-helix II and beta-strand III. A similar structural feature is also present in the other groups of cyclophilins, namely, those from invertebrates, other metazoa, plants, and fungi. The sequences of cyclophilins from fungi and prokaryotes are more diversified than those from vertebrates, and their alterations involve structures other than the amino acid inserts within the loops. Variations of the hydrophobicity and bulkiness of amino acid substitutions of the aligned sequences were calculated for each group of cyclophilins and for the alignment of all the sequences. The variations have clear asymmetry that may signify the need for modification of the physical properties of certain fragments of cyclophilins that are involved in interactions with various cellular components in the evolving environment.
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Affiliation(s)
- A Galat
- Département d'Ingénierie et d'Etudes des Protéines, DSV/CEA, Gif-sur-Yvette Cedex, CE-Saclay, F-91191, France
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28
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Abstract
This article reviews the involvement of the mitochondrial permeability transition pore in necrotic and apoptotic cell death. The pore is formed from a complex of the voltage-dependent anion channel (VDAC), the adenine nucleotide translocase and cyclophilin-D (CyP-D) at contact sites between the mitochondrial outer and inner membranes. In vitro, under pseudopathological conditions of oxidative stress, relatively high Ca2+ and low ATP, the complex flickers into an open-pore state allowing free diffusion of low-Mr solutes across the inner membrane. These conditions correspond to those that unfold during tissue ischaemia and reperfusion, suggesting that pore opening may be an important factor in the pathogenesis of necrotic cell death following ischaemia/reperfusion. Evidence that the pore does open during ischaemia/reperfusion is discussed. There are also strong indications that the VDAC-adenine nucleotide translocase-CyP-D complex can recruit a number of other proteins, including Bax, and that the complex is utilized in some capacity during apoptosis. The apoptotic pathway is amplified by the release of apoptogenic proteins from the mitochondrial intermembrane space, including cytochrome c, apoptosis-inducing factor and some procaspases. Current evidence that the pore complex is involved in outer-membrane rupture and release of these proteins during programmed cell death is reviewed, along with indications that transient pore opening may provoke 'accidental' apoptosis.
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29
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Crompton M. The mitochondrial permeability transition pore and its role in cell death. Biochem J 1999; 341 ( Pt 2):233-49. [PMID: 10393078 PMCID: PMC1220352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
This article reviews the involvement of the mitochondrial permeability transition pore in necrotic and apoptotic cell death. The pore is formed from a complex of the voltage-dependent anion channel (VDAC), the adenine nucleotide translocase and cyclophilin-D (CyP-D) at contact sites between the mitochondrial outer and inner membranes. In vitro, under pseudopathological conditions of oxidative stress, relatively high Ca2+ and low ATP, the complex flickers into an open-pore state allowing free diffusion of low-Mr solutes across the inner membrane. These conditions correspond to those that unfold during tissue ischaemia and reperfusion, suggesting that pore opening may be an important factor in the pathogenesis of necrotic cell death following ischaemia/reperfusion. Evidence that the pore does open during ischaemia/reperfusion is discussed. There are also strong indications that the VDAC-adenine nucleotide translocase-CyP-D complex can recruit a number of other proteins, including Bax, and that the complex is utilized in some capacity during apoptosis. The apoptotic pathway is amplified by the release of apoptogenic proteins from the mitochondrial intermembrane space, including cytochrome c, apoptosis-inducing factor and some procaspases. Current evidence that the pore complex is involved in outer-membrane rupture and release of these proteins during programmed cell death is reviewed, along with indications that transient pore opening may provoke 'accidental' apoptosis.
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Affiliation(s)
- M Crompton
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, U.K.
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30
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Kropotov A, Sedova V, Ivanov V, Sazeeva N, Tomilin A, Krutilina R, Oei SL, Griesenbeck J, Buchlow G, Tomilin N. A novel human DNA-binding protein with sequence similarity to a subfamily of redox proteins which is able to repress RNA-polymerase-III-driven transcription of the Alu-family retroposons in vitro. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:336-46. [PMID: 10095767 DOI: 10.1046/j.1432-1327.1999.00162.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this study we identified a novel protein which may contribute to the transcriptional inactivity of Alu retroposons in vivo. A human cDNA clone encoding this protein (ACR1) was isolated from a human expression library using South-western screening with an Alu subfragment, implicated in the regulation of Alu in vitro transcription and interacting with a HeLa nuclear protein down-regulated in adenovirus-infected cells. Bacterially expressed ACR1 is demonstrated to inhibit RNA polymerase III (Pol III)-dependent Alu transcription in vitro but showed no repression of transcription of a tRNA gene or of a reporter gene under control of a Pol II promoter. ACR1 mRNA is also found to be down-regulated in adenovirus-infected HeLa cells, consistent with a possible repressor function of the protein in vivo. ACR1 is mainly (but not exclusively) located in cytoplasm and appears to be a member of a weakly characterized redox protein family having a central, highly conserved sequence motif, PGAFTPXCXXXXLP. One member of the family identified earlier as peroxisomal membrane protein (PMP)20 is known to interact in a sequence-specific manner with a yeast homolog of mammalian cyclosporin-A-binding protein cyclophilin, and mammalian cyclophilin A (an abundant ubiquitously expressed protein) is known to interact with human transcriptional repressor YY1, which is a major sequence-specific Alu-binding protein in human cells. It appears, therefore, that transcriptional silencing of Alu in vivo is a result of complex interactions of many proteins which bind to its Pol III promoter.
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Affiliation(s)
- A Kropotov
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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31
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Bunz F, Dutriaux A, Lengauer C, Waldman T, Zhou S, Brown JP, Sedivy JM, Kinzler KW, Vogelstein B. Requirement for p53 and p21 to sustain G2 arrest after DNA damage. Science 1998; 282:1497-501. [PMID: 9822382 DOI: 10.1126/science.282.5393.1497] [Citation(s) in RCA: 2265] [Impact Index Per Article: 87.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
After DNA damage, many cells appear to enter a sustained arrest in the G2 phase of the cell cycle. It is shown here that this arrest could be sustained only when p53 was present in the cell and capable of transcriptionally activating the cyclin-dependent kinase inhibitor p21. After disruption of either the p53 or the p21 gene, gamma radiated cells progressed into mitosis and exhibited a G2 DNA content only because of a failure of cytokinesis. Thus, p53 and p21 appear to be essential for maintaining the G2 checkpoint in human cells.
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Affiliation(s)
- F Bunz
- The Howard Hughes Medical Institute and The Johns Hopkins Oncology Center, 424 North Bond Street, Baltimore, MD 21231, USA
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32
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Hong X, Ma D, Carlow CK. Cloning, expression and characterization of a new filarial cyclophilin. Mol Biochem Parasitol 1998; 91:353-8. [PMID: 9566526 DOI: 10.1016/s0166-6851(97)00219-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- X Hong
- New England Biolabs, Beverly, MA 01915, USA
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