1
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Chang R, Tsui KH, Pan LF, Li CJ. Spatial and single-cell analyses uncover links between ALKBH1 and tumor-associated macrophages in gastric cancer. Cancer Cell Int 2024; 24:57. [PMID: 38317214 PMCID: PMC10845659 DOI: 10.1186/s12935-024-03232-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/19/2024] [Indexed: 02/07/2024] Open
Abstract
BACKGROUND AlkB homolog 1, histone H2A dioxygenase (ALKBH1), a crucial enzyme involved in RNA demethylation in humans, plays a significant role in various cellular processes. While its role in tumor progression is well-established, its specific contribution to stomach adenocarcinoma (STAD) remains elusive. This study seeks to explore the clinical and pathological relevance of ALKBH1, its impact on the tumor immune microenvironment, and its potential for precision oncology in STAD. METHODS We adopted a comprehensive multi-omics approach to identify ALKBH1 as an potential diagnostic biomarker for STAD, demonstrating its association with advanced clinical stages and reduced overall survival rates. Our analysis involved the utilization of publicly available datasets from GEO and TCGA. We identified differentially expressed genes in STAD and scrutinized their relationships with immune gene expression, overall survival, tumor stage, gene mutation profiles, and infiltrating immune cells. Moreover, we employed spatial transcriptomics to investigate ALKBH1 expression across distinct regions of STAD. Additionally, we conducted spatial transcriptomic and single-cell RNA-sequencing analyses to elucidate the correlation between ALKBH1 expression and immune cell populations. Our findings were validated through immunohistochemistry and bioinformatics on 60 STAD patient samples. RESULTS Our study unveiled crucial gene regulators in STAD linked with genetic variations, deletions, and the tumor microenvironment. Mutations in these regulators demonstrated a positive association with distinct immune cell populations across six immune datasets, exerting a substantial influence on immune cell infiltration in STAD. Furthermore, we established a connection between elevated ALKBH1 expression and macrophage infiltration in STAD. Pharmacogenomic analysis of gastric cancer cell lines further indicated that ALKBH1 inactivation correlated with heightened sensitivity to specific small-molecule drugs. CONCLUSION In conclusion, our study highlights the potential role of ALKBH1 alterations in the advancement of STAD, shedding light on novel diagnostic and prognostic applications of ALKBH1 in this context. We underscore the significance of ALKBH1 within the tumor immune microenvironment, suggesting its utility as a precision medicine tool and for drug screening in the management of STAD.
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Affiliation(s)
- Renin Chang
- Department of Emergency Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
- Department of Recreation and Sports Management, Tajen University, Pingtung, Taiwan
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Kuan-Hao Tsui
- Department of Obstetrics and Gynaecology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
- Institute of BioPharmaceutical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan
- Department of Obstetrics and Gynaecology, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, 114, Taiwan
| | - Li-Fei Pan
- Department of General Affair Office, Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan
| | - Chia-Jung Li
- Department of Obstetrics and Gynaecology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
- Institute of BioPharmaceutical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.
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2
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Peng Z, Ma J, Christov CZ, Karabencheva-Christova T, Lehnert N, Li D. Kinetic Studies on the 2-Oxoglutarate/Fe(II)-Dependent Nucleic Acid Modifying Enzymes from the AlkB and TET Families. DNA 2023; 3:65-84. [PMID: 38698914 PMCID: PMC11065319 DOI: 10.3390/dna3020005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Nucleic acid methylations are important genetic and epigenetic biomarkers. The formation and removal of these markers is related to either methylation or demethylation. In this review, we focus on the demethylation or oxidative modification that is mediated by the 2-oxoglutarate (2-OG)/Fe(II)-dependent AlkB/TET family enzymes. In the catalytic process, most enzymes oxidize 2-OG to succinate, in the meantime oxidizing methyl to hydroxymethyl, leaving formaldehyde and generating demethylated base. The AlkB enzyme from Escherichia coli has nine human homologs (ALKBH1-8 and FTO) and the TET family includes three members, TET1 to 3. Among them, some enzymes have been carefully studied, but for certain enzymes, few studies have been carried out. This review focuses on the kinetic properties of those 2-OG/Fe(II)-dependent enzymes and their alkyl substrates. We also provide some discussions on the future directions of this field.
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Affiliation(s)
- Zhiyuan Peng
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Jian Ma
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Christo Z. Christov
- Department of Chemistry, Michigan Technological University, Houghton, MI 49931, USA
| | | | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Deyu Li
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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3
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Kietzmann T. Vitamin C: From nutrition to oxygen sensing and epigenetics. Redox Biol 2023; 63:102753. [PMID: 37263060 DOI: 10.1016/j.redox.2023.102753] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/09/2023] [Accepted: 05/16/2023] [Indexed: 06/03/2023] Open
Abstract
Vitamin C is unbeatable - at least when it comes to sales. Of all the vitamin preparations, those containing vitamin C sell best. This is surprising because vitamin C deficiency is extremely rare. Nevertheless, there is still controversy about whether the additional intake of vitamin C supplements is essential for our health. In this context, the possible additional benefit is in most cases merely reduced to the known effect as an antioxidant. However, new findings in recent years on the mechanisms of oxygen-sensing and epigenetic control underpin the multifaceted role of vitamin C in a biological context and have therefore renewed interest in it. In the present article, therefore, known facts are linked to these new key data. In addition, available clinical data on vitamin C use of cancer therapy are summarized.
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Affiliation(s)
- Thomas Kietzmann
- University of Oulu, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, P.O. Box 3000, 90014, Oulu, Finland.
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4
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Li Q, Zhu Q. The role of demethylase AlkB homologs in cancer. Front Oncol 2023; 13:1153463. [PMID: 37007161 PMCID: PMC10060643 DOI: 10.3389/fonc.2023.1153463] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
The AlkB family (ALKBH1-8 and FTO), a member of the Fe (II)- and α-ketoglutarate-dependent dioxygenase superfamily, has shown the ability to catalyze the demethylation of a variety of substrates, including DNA, RNA, and histones. Methylation is one of the natural organisms’ most prevalent forms of epigenetic modifications. Methylation and demethylation processes on genetic material regulate gene transcription and expression. A wide variety of enzymes are involved in these processes. The methylation levels of DNA, RNA, and histones are highly conserved. Stable methylation levels at different stages can coordinate the regulation of gene expression, DNA repair, and DNA replication. Dynamic methylation changes are essential for the abilities of cell growth, differentiation, and division. In some malignancies, the methylation of DNA, RNA, and histones is frequently altered. To date, nine AlkB homologs as demethylases have been identified in numerous cancers’ biological processes. In this review, we summarize the latest advances in the research of the structures, enzymatic activities, and substrates of the AlkB homologs and the role of these nine homologs as demethylases in cancer genesis, progression, metastasis, and invasion. We provide some new directions for the AlkB homologs in cancer research. In addition, the AlkB family is expected to be a new target for tumor diagnosis and treatment.
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Affiliation(s)
- Qiao Li
- Department of Orthopedic Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin, China
- Department of Spine Surgery, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Qingsan Zhu
- Department of Orthopedic Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin, China
- *Correspondence: Qingsan Zhu,
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5
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Cavallin I, Bartosovic M, Skalicky T, Rengaraj P, Demko M, Schmidt-Dengler MC, Drino A, Helm M, Vanacova S. HITS-CLIP analysis of human ALKBH8 reveals interactions with fully processed substrate tRNAs and with specific noncoding RNAs. RNA (NEW YORK, N.Y.) 2022; 28:1568-1581. [PMID: 36192131 PMCID: PMC9670814 DOI: 10.1261/rna.079421.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
Transfer RNAs acquire a large plethora of chemical modifications. Among those, modifications of the anticodon loop play important roles in translational fidelity and tRNA stability. Four human wobble U-containing tRNAs obtain 5-methoxycarbonylmethyluridine (mcm5U34) or 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U34), which play a role in decoding. This mark involves a cascade of enzymatic activities. The last step is mediated by alkylation repair homolog 8 (ALKBH8). In this study, we performed a transcriptome-wide analysis of the repertoire of ALKBH8 RNA targets. Using a combination of HITS-CLIP and RIP-seq analyses, we uncover ALKBH8-bound RNAs. We show that ALKBH8 targets fully processed and CCA modified tRNAs. Our analyses uncovered the previously known set of wobble U-containing tRNAs. In addition, both our approaches revealed ALKBH8 binding to several other types of noncoding RNAs, in particular C/D box snoRNAs.
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Affiliation(s)
- Ivana Cavallin
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Marek Bartosovic
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Tomas Skalicky
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 370 05 České Budějovice, Czech Republic
| | - Praveenkumar Rengaraj
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Martin Demko
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | | | - Aleksej Drino
- Medical University of Vienna, Center for Anatomy and Cell Biology, 1090 Vienna, Austria
| | - Mark Helm
- Johannes Gutenberg-Universität Mainz, Institute of Pharmaceutical and Biomedical Science (IPBS), D-55128 Mainz, Germany
| | - Stepanka Vanacova
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
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6
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Zhao Y, Guo Q, Cao S, Tian Y, Han K, Sun Y, Li J, Yang Q, Ji Q, Sederoff R, Li Y. Genome-wide identification of the AlkB homologs gene family, PagALKBH9B and PagALKBH10B regulated salt stress response in Populus. FRONTIERS IN PLANT SCIENCE 2022; 13:994154. [PMID: 36204058 PMCID: PMC9530910 DOI: 10.3389/fpls.2022.994154] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/26/2022] [Indexed: 06/16/2023]
Abstract
The AlkB homologs (ALKBH) gene family regulates N6-methyladenosine (m6A) RNA methylation and is involved in plant growth and the abiotic stress response. Poplar is an important model plant for studying perennial woody plants. Poplars typically have a long juvenile period of 7-10 years, requiring long periods of time for studies of flowering or mature wood properties. Consequently, functional studies of the ALKBH genes in Populus species have been limited. Based on AtALKBHs sequence similarity with Arabidopsis thaliana, 23 PagALKBHs were identified in the genome of the poplar 84K hybrid genotype (P. alba × P. tremula var. glandulosa), and gene structures and conserved domains were confirmed between homologs. The PagALKBH proteins were classified into six groups based on conserved sequence compared with human, Arabidopsis, maize, rice, wheat, tomato, barley, and grape. All homologs of PagALKBHs were tissue-specific; most were highly expressed in leaves. ALKBH9B and ALKBH10B are m6A demethylases and overexpression of their homologs PagALKBH9B and PagALKBH10B reduced m6A RNA methylation in transgenic lines. The number of adventitious roots and the biomass accumulation of transgenic lines decreased compared with WT. Therefore, PagALKBH9B and PagALKBH10B mediate m6A RNA demethylation and play a regulatory role in poplar growth and development. Overexpression of PagALKBH9B and PagALKBH10B can reduce the accumulation of H2O2 and oxidative damage by increasing the activities of SOD, POD, and CAT, and enhancing protection for Chl a/b, thereby increasing the salt tolerance of transgenic lines. However, overexpression lines were more sensitive to drought stress due to reduced proline content. This research revealed comprehensive information about the PagALKBH gene family and their roles in growth and development and responsing to salt stress of poplar.
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Affiliation(s)
- Ye Zhao
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Qi Guo
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Sen Cao
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Yanting Tian
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Kunjin Han
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Yuhan Sun
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Juan Li
- Natural Resources and Planning Bureau of Yanshan County, Cangzhou, Hebei, China
| | - Qingshan Yang
- Shandong Academy of Forestry, Jinan, Shandong, China
| | - Qingju Ji
- Cangzhou Municipal Forestry Seeding and Cutting Management Center, Cangzhou, China
| | - Ronald Sederoff
- Forest Biotechnology Group, Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, United States
| | - Yun Li
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, College of Biological Sciences and Technology, National Engineering Research Center of Tree Breeding and Ecological Restoration, Engineering Technology Research Center of Black Locust of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
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7
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Boulias K, Greer EL. Means, mechanisms and consequences of adenine methylation in DNA. Nat Rev Genet 2022; 23:411-428. [PMID: 35256817 PMCID: PMC9354840 DOI: 10.1038/s41576-022-00456-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2022] [Indexed: 12/29/2022]
Abstract
N6-methyl-2'-deoxyadenosine (6mA or m6dA) has been reported in the DNA of prokaryotes and eukaryotes ranging from unicellular protozoa and algae to multicellular plants and mammals. It has been proposed to modulate DNA structure and transcription, transmit information across generations and have a role in disease, among other functions. However, its existence in more recently evolved eukaryotes remains a topic of debate. Recent technological advancements have facilitated the identification and quantification of 6mA even when the modification is exceptionally rare, but each approach has limitations. Critical assessment of existing data, rigorous design of future studies and further development of methods will be required to confirm the presence and biological functions of 6mA in multicellular eukaryotes.
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8
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O’Brown ZK, Greer EL. N6-methyladenine: A Rare and Dynamic DNA Mark. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1389:177-210. [DOI: 10.1007/978-3-031-11454-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Zhao S, Devega R, Francois A, Kidane D. Human ALKBH6 Is Required for Maintenance of Genomic Stability and Promoting Cell Survival During Exposure of Alkylating Agents in Pancreatic Cancer. Front Genet 2021; 12:635808. [PMID: 33897761 PMCID: PMC8058185 DOI: 10.3389/fgene.2021.635808] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/08/2021] [Indexed: 12/21/2022] Open
Abstract
Alpha-ketoglutarate-dependent dioxygenase (ALKBH) is a DNA repair gene involved in the repair of alkylating DNA damage. There are nine types of ALKBH (ALKBH1-8 and FTO) identified in humans. In particular, certain types of ALKBH enzymes are dioxygenases that directly reverse DNA methylation damage via transfer of a methyl group from the DNA adduct onto α-ketoglutarate and release of metabolic products including succinate and formaldehyde. Here, we tested whether ALKBH6 plays a significant role in preventing alkylating DNA damage and decreasing genomic instability in pancreatic cancer cells. Using an E. coli strain deficient with ALKB, we found that ALKBH6 complements ALKB deficiency and increases resistance after alkylating agent treatment. In particular, the loss of ALKBH6 in human pancreatic cancer cells increases alkylating agent-induced DNA damage and significantly decreases cell survival. Furthermore, in silico analysis from The Cancer Genome Atlas (TCGA) database suggests that overexpression of ALKBH6 provides better survival outcomes in patients with pancreatic cancer. Overall, our data suggest that ALKBH6 is required to maintain the integrity of the genome and promote cell survival of pancreatic cancer cells.
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Affiliation(s)
- Shengyuan Zhao
- Division of Pharmacology and Toxicology, College of Pharmacy, Dell Pediatric Research Institute, The University of Texas at Austin, Austin, TX, United States
| | - Rodan Devega
- Division of Pharmacology and Toxicology, College of Pharmacy, Dell Pediatric Research Institute, The University of Texas at Austin, Austin, TX, United States
| | - Aaliyah Francois
- Division of Pharmacology and Toxicology, College of Pharmacy, Dell Pediatric Research Institute, The University of Texas at Austin, Austin, TX, United States
| | - Dawit Kidane
- Division of Pharmacology and Toxicology, College of Pharmacy, Dell Pediatric Research Institute, The University of Texas at Austin, Austin, TX, United States
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10
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Xu B, Liu D, Wang Z, Tian R, Zuo Y. Multi-substrate selectivity based on key loops and non-homologous domains: new insight into ALKBH family. Cell Mol Life Sci 2021; 78:129-141. [PMID: 32642789 PMCID: PMC11072825 DOI: 10.1007/s00018-020-03594-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/24/2020] [Accepted: 07/03/2020] [Indexed: 12/16/2022]
Abstract
AlkB homologs (ALKBH) are a family of specific demethylases that depend on Fe2+ and α-ketoglutarate to catalyze demethylation on different substrates, including ssDNA, dsDNA, mRNA, tRNA, and proteins. Previous studies have made great progress in determining the sequence, structure, and molecular mechanism of the ALKBH family. Here, we first review the multi-substrate selectivity of the ALKBH demethylase family from the perspective of sequence and structural evolution. The construction of the phylogenetic tree and the comparison of key loops and non-homologous domains indicate that the paralogs with close evolutionary relationship have similar domain compositions. The structures show that the lack and variations of four key loops change the shape of clefts to cause the differences in substrate affinity, and non-homologous domains may be related to the compatibility of multiple substrates. We anticipate that the new insights into selectivity determinants of the ALKBH family are useful for understanding the demethylation mechanisms.
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Affiliation(s)
- Baofang Xu
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Dongyang Liu
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zerong Wang
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Ruixia Tian
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Yongchun Zuo
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
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11
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Van Deuren V, Plessers S, Robben J. Structural determinants of nucleobase modification recognition in the AlkB family of dioxygenases. DNA Repair (Amst) 2020; 96:102995. [PMID: 33069898 DOI: 10.1016/j.dnarep.2020.102995] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 09/30/2020] [Indexed: 01/29/2023]
Abstract
Iron-dependent dioxygenases of the AlkB protein family found in most organisms throughout the tree of life play a major role in oxidative dealkylation processes. Many of these enzymes have attracted the attention of researchers across different fields and have been subjected to thorough biochemical characterization because of their link to human health and disease. For example, several mammalian AlkB homologues are involved in the direct reversal of alkylation damage in DNA, while others have been shown to play a regulatory role in epigenetic or epitranscriptomic nucleic acid methylation or in post-translational modifications such as acetylation of actin filaments. These studies show that that divergence in amino acid sequence and structure leads to different characteristics and substrate specificities. In this review, we aim to summarize current insights in the structural features involved in the substrate selection of AlkB homologues, with focus on nucleic acid interactions.
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Affiliation(s)
- V Van Deuren
- Department of Chemistry, KU Leuven, Celestijnenlaan 200G, B-3001, Heverlee, Belgium
| | - S Plessers
- Department of Chemistry, KU Leuven, Celestijnenlaan 200G, B-3001, Heverlee, Belgium
| | - J Robben
- Department of Chemistry, KU Leuven, Celestijnenlaan 200G, B-3001, Heverlee, Belgium.
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12
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Marcinkowski M, Pilžys T, Garbicz D, Steciuk J, Zugaj D, Mielecki D, Sarnowski TJ, Grzesiuk E. Human and Arabidopsis alpha-ketoglutarate-dependent dioxygenase homolog proteins-New players in important regulatory processes. IUBMB Life 2020; 72:1126-1144. [PMID: 32207231 DOI: 10.1002/iub.2276] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 02/20/2020] [Accepted: 03/08/2020] [Indexed: 12/31/2022]
Abstract
The family of AlkB homolog (ALKBH) proteins, the homologs of Escherichia coli AlkB 2-oxoglutarate (2OG), and Fe(II)-dependent dioxygenase are involved in a number of important regulatory processes in eukaryotic cells including repair of alkylation lesions in DNA, RNA, and nucleoprotein complexes. There are nine human and thirteen Arabidopsis thaliana ALKBH proteins described, which exhibit diversified functions. Among them, human ALKBH5 and FaT mass and Obesity-associated (FTO) protein and Arabidopsis ALKBH9B and ALKBH10B have been recognized as N6 methyladenine (N6 meA) demethylases, the most abundant posttranscriptional modification in mRNA. The FTO protein is reported to be associated with obesity and type 2 diabetes, and involved in multiple other processes, while ALKBH5 is induced by hypoxia. Arabidopsis ALKBH9B is an N6 meA demethylase influencing plant susceptibility to viral infections via m6 A/A ratio control in viral RNA. ALKBH10B has been discovered to be a functional Arabidopsis homolog of FTO; thus, it is also an RNA N6 meA demethylase involved in plant flowering and several other regulatory processes including control of metabolism. High-throughput mass spectrometry showed multiple sites of human ALKBH phosphorylation. In the case of FTO, the type of modified residue decides about the further processing of the protein. This modification may result in subsequent protein ubiquitination and proteolysis, or in the blocking of these processes. However, the impact of phosphorylation on the other ALKBH function and their downstream pathways remains nearly unexplored in both human and Arabidopsis. Therefore, the investigation of evolutionarily conserved functions of ALKBH proteins and their regulatory impact on important cellular processes is clearly called for.
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Affiliation(s)
- Michał Marcinkowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Tomaš Pilžys
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Damian Garbicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Jaroslaw Steciuk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Dorota Zugaj
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Damian Mielecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Tomasz J Sarnowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Elżbieta Grzesiuk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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13
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Mammalian ALKBH1 serves as an N 6-mA demethylase of unpairing DNA. Cell Res 2020; 30:197-210. [PMID: 32051560 PMCID: PMC7054317 DOI: 10.1038/s41422-019-0237-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/30/2019] [Indexed: 01/07/2023] Open
Abstract
N6-methyladenine (N6-mA) of DNA is an emerging epigenetic mark in mammalian genome. Levels of N6-mA undergo drastic fluctuation during early embryogenesis, indicative of active regulation. Here we show that the 2-oxoglutarate-dependent oxygenase ALKBH1 functions as a nuclear eraser of N6-mA in unpairing regions (e.g., SIDD, Stress-Induced DNA Double Helix Destabilization regions) of mammalian genomes. Enzymatic profiling studies revealed that ALKBH1 prefers bubbled or bulged DNAs as substrate, instead of single-stranded (ss-) or double-stranded (ds-) DNAs. Structural studies of ALKBH1 revealed an unexpected "stretch-out" conformation of its "Flip1" motif, a conserved element that usually bends over catalytic center to facilitate substrate base flipping in other DNA demethylases. Thus, lack of a bending "Flip1" explains the observed preference of ALKBH1 for unpairing substrates, in which the flipped N6-mA is primed for catalysis. Co-crystal structural studies of ALKBH1 bound to a 21-mer bulged DNA explained the need of both flanking duplexes and a flipped base for recognition and catalysis. Key elements (e.g., an ALKBH1-specific α1 helix) as well as residues contributing to structural integrity and catalytic activity were validated by structure-based mutagenesis studies. Furthermore, ssDNA-seq and DIP-seq analyses revealed significant co-occurrence of base unpairing regions with N6-mA in mouse genome. Collectively, our biochemical, structural and genomic studies suggest that ALKBH1 is an important DNA demethylase that regulates genome N6-mA turnover of unpairing regions associated with dynamic chromosome regulation.
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Rajecka V, Skalicky T, Vanacova S. The role of RNA adenosine demethylases in the control of gene expression. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:343-355. [PMID: 30550773 DOI: 10.1016/j.bbagrm.2018.12.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/30/2018] [Accepted: 12/07/2018] [Indexed: 01/21/2023]
Abstract
RNA modifications are being recognized as an essential factor in gene expression regulation. They play essential roles in germ line development, differentiation and disease. In eukaryotic mRNAs, N6-adenosine methylation (m6A) is the most prevalent internal chemical modification identified to date. The m6A pathway involves factors called writers, readers and erasers. m6A thus offers an interesting concept of dynamic reversible modification with implications in fine-tuning the cellular metabolism. In mammals, FTO and ALKBH5 have been initially identified as m6A erasers. Recently, FTO m6A specificity has been debated as new reports identify FTO targeting N6,2'-O-dimethyladenosine (m6Am). The two adenosine demethylases have diverse roles in the metabolism of mRNAs and their activity is involved in key processes, such as embryogenesis, disease or infection. In this article, we review the current knowledge of their function and mechanisms and discuss the existing contradictions in the field. This article is part of a Special Issue entitled: mRNA modifications in gene expression control edited by Dr. Soller Matthias and Dr. Fray Rupert.
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Affiliation(s)
- Veronika Rajecka
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 625 00, Czech Republic
| | - Tomas Skalicky
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 625 00, Czech Republic
| | - Stepanka Vanacova
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 625 00, Czech Republic.
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Kawarada L, Suzuki T, Ohira T, Hirata S, Miyauchi K, Suzuki T. ALKBH1 is an RNA dioxygenase responsible for cytoplasmic and mitochondrial tRNA modifications. Nucleic Acids Res 2017; 45:7401-7415. [PMID: 28472312 PMCID: PMC5499545 DOI: 10.1093/nar/gkx354] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/17/2017] [Accepted: 04/22/2017] [Indexed: 11/13/2022] Open
Abstract
ALKBH1 is a 2-oxoglutarate- and Fe2+-dependent dioxygenase responsible for multiple cellular functions. Here, we show that ALKBH1 is involved in biogenesis of 5-hydroxymethyl-2΄-O-methylcytidine (hm5Cm) and 5-formyl-2΄-O-methylcytidine (f5Cm) at the first position (position 34) of anticodon in cytoplasmic tRNALeu, as well as f5C at the same position in mitochondrial tRNAMet. Because f5C34 of mitochondrial tRNAMet is essential for translation of AUA, a non-universal codon in mammalian mitochondria, ALKBH1-knockout cells exhibited a strong reduction in mitochondrial translation and reduced respiratory complex activities, indicating that f5C34 formation mediated by ALKBH1 is required for efficient mitochondrial functions. We reconstituted formation of f5C34 on mitochondrial tRNAMetin vitro, and found that ALKBH1 first hydroxylated m5C34 to form hm5C34, and then oxidized hm5C34 to form f5C34. Moreover, we found that the frequency of 1-methyladenosine (m1A) in two mitochondrial tRNAs increased in ALKBH1-knockout cells, indicating that ALKBH1 also has demethylation activity toward m1A in mt-tRNAs. Based on these results, we conclude that nuclear and mitochondrial ALKBH1 play distinct roles in tRNA modification.
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Affiliation(s)
- Layla Kawarada
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takayuki Ohira
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shoji Hirata
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kenjyo Miyauchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Tudek B, Zdżalik-Bielecka D, Tudek A, Kosicki K, Fabisiewicz A, Speina E. Lipid peroxidation in face of DNA damage, DNA repair and other cellular processes. Free Radic Biol Med 2017; 107:77-89. [PMID: 27908783 DOI: 10.1016/j.freeradbiomed.2016.11.043] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/20/2016] [Accepted: 11/27/2016] [Indexed: 01/09/2023]
Abstract
Exocyclic adducts to DNA bases are formed as a consequence of exposure to certain environmental carcinogens as well as inflammation and lipid peroxidation (LPO). Complex family of LPO products gives rise to a variety of DNA adducts, which can be grouped in two classes: (i) small etheno-type adducts of strong mutagenic potential, and (ii) bulky, propano-type adducts, which block replication and transcription, and are lethal lesions. Etheno-DNA adducts are removed from the DNA by base excision repair (BER), AlkB and nucleotide incision repair enzymes (NIR), while substituted propano-type lesions by nucleotide excision repair (NER) and homologous recombination (HR). Changes of the level and activity of several enzymes removing exocyclic adducts from the DNA was reported during carcinogenesis. Also several beyond repair functions of these enzymes, which participate in regulation of cell proliferation and growth, as well as RNA processing was recently described. In addition, adducts of LPO products to proteins was reported during aging and age-related diseases. The paper summarizes pathways for exocyclic adducts removal and describes how proteins involved in repair of these adducts can modify pathological states of the organism.
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Affiliation(s)
- Barbara Tudek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Daria Zdżalik-Bielecka
- Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Ksiecia Trojdena 4, 02-109 Warsaw, Poland
| | - Agnieszka Tudek
- Department of Molecular Biology and Genetics, Aarhus University, C. F. Mollers Alle 3, 8000 Aarhus, Denmark
| | - Konrad Kosicki
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Anna Fabisiewicz
- Department of Molecular and Translational Oncology, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Roentgena 5, Warsaw 02-781, Poland
| | - Elżbieta Speina
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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O'Brown ZK, Greer EL. N6-Methyladenine: A Conserved and Dynamic DNA Mark. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 945:213-246. [PMID: 27826841 DOI: 10.1007/978-3-319-43624-1_10] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Chromatin, consisting of deoxyribonucleic acid (DNA) wrapped around histone proteins, facilitates DNA compaction and allows identical DNA codes to confer many different cellular phenotypes. This biological versatility is accomplished in large part by posttranslational modifications to histones and chemical modifications to DNA. These modifications direct the cellular machinery to expand or compact specific chromatin regions and mark regions of the DNA as important for cellular functions. While each of the four bases that make up DNA can be modified (Iyer et al. 2011), this chapter will focus on methylation of the sixth position on adenines (6mA), as this modification has been poorly characterized in recently evolved eukaryotes, but shows promise as a new conserved layer of epigenetic regulation. 6mA was previously thought to be restricted to unicellular organisms, but recent work has revealed its presence in metazoa. Here, we will briefly describe the history of 6mA, examine its evolutionary conservation, and evaluate the current methods for detecting 6mA. We will discuss the enzymes that bind and regulate this mark and finally examine known and potential functions of 6mA in eukaryotes.
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Affiliation(s)
- Zach Klapholz O'Brown
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Eric Lieberman Greer
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA. .,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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18
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Ougland R, Rognes T, Klungland A, Larsen E. Non-homologous functions of the AlkB homologs. J Mol Cell Biol 2015; 7:494-504. [PMID: 26003568 DOI: 10.1093/jmcb/mjv029] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/26/2015] [Indexed: 12/22/2022] Open
Abstract
The DNA repair enzyme AlkB was identified in E. coli more than three decades ago. Since then, nine mammalian homologs, all members of the superfamily of alpha-ketoglutarate and Fe(II)-dependent dioxygenases, have been identified (designated ALKBH1-8 and FTO). While E. coli AlkB serves as a DNA repair enzyme, only two mammalian homologs have been confirmed to repair DNA in vivo. The other mammalian homologs have remarkably diverse substrate specificities and biological functions. Substrates recognized by the different AlkB homologs comprise erroneous methyl- and etheno adducts in DNA, unique wobble uridine modifications in certain tRNAs, methylated adenines in mRNA, and methylated lysines on proteins. The phenotypes of organisms lacking or overexpressing individual AlkB homologs include obesity, severe sensitivity to inflammation, infertility, growth retardation, and multiple malformations. Here we review the present knowledge of the mammalian AlkB homologs and their implications for human disease and development.
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Affiliation(s)
- Rune Ougland
- Clinic for Diagnostics and Intervention and Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway Department of Anesthesiology, Division of Emergencies and Critical Care, Oslo University Hospital, The Norwegian Radium Hospital, 0310 Oslo, Norway
| | - Torbjørn Rognes
- Clinic for Diagnostics and Intervention and Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway Department of Informatics, University of Oslo, 0316 Oslo, Norway
| | - Arne Klungland
- Clinic for Diagnostics and Intervention and Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Elisabeth Larsen
- Clinic for Diagnostics and Intervention and Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway
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Lu L, Zhu C, Xia B, Yi C. Oxidative Demethylation of DNA and RNA Mediated by Non-Heme Iron-Dependent Dioxygenases. Chem Asian J 2014; 9:2018-29. [DOI: 10.1002/asia.201402148] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Indexed: 11/10/2022]
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20
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Affiliation(s)
- Guanqun Zheng
- Department of Chemistry and
Institute for Biophysical Dynamics, The
University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United
States
| | - Ye Fu
- Department of Chemistry and
Institute for Biophysical Dynamics, The
University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United
States
| | - Chuan He
- Department of Chemistry and
Institute for Biophysical Dynamics, The
University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United
States
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21
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Affiliation(s)
- Guanqun Zheng
- Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago , 929 East 57th Street, Chicago, Illinois 60637, United States
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22
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Ougland R, Lando D, Jonson I, Dahl JA, Moen MN, Nordstrand LM, Rognes T, Lee JT, Klungland A, Kouzarides T, Larsen E. ALKBH1 is a histone H2A dioxygenase involved in neural differentiation. Stem Cells 2013; 30:2672-82. [PMID: 22961808 PMCID: PMC3546389 DOI: 10.1002/stem.1228] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 08/19/2012] [Indexed: 12/18/2022]
Abstract
AlkB homolog 1 (ALKBH1) is one of nine members of the family of mammalian AlkB homologs. Most Alkbh1(-/-) mice die during embryonic development, and survivors are characterized by defects in tissues originating from the ectodermal lineage. In this study, we show that deletion of Alkbh1 prolonged the expression of pluripotency markers in embryonic stem cells and delayed the induction of genes involved in early differentiation. In vitro differentiation to neural progenitor cells (NPCs) displayed an increased rate of apoptosis in the Alkbh1(-/-) NPCs when compared with wild-type cells. Whole-genome expression analysis and chromatin immunoprecipitation revealed that ALKBH1 regulates both directly and indirectly, a subset of genes required for neural development. Furthermore, our in vitro enzyme activity assays demonstrate that ALKBH1 is a histone dioxygenase that acts specifically on histone H2A. Mass spectrometric analysis demonstrated that histone H2A from Alkbh1(-/-) mice are improperly methylated. Our results suggest that ALKBH1 is involved in neural development by modifying the methylation status of histone H2A.
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Affiliation(s)
- Rune Ougland
- Centre for Molecular Biology and Neuroscience, Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet and University of Oslo, Oslo, Norway
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Solberg A, Robertson AB, Aronsen JM, Rognmo Ø, Sjaastad I, Wisløff U, Klungland A. Deletion of mouse Alkbh7 leads to obesity. J Mol Cell Biol 2013; 5:194-203. [PMID: 23572141 DOI: 10.1093/jmcb/mjt012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mammals have nine homologues of the Escherichia coli AlkB repair protein: Alkbh1-8, and the fat mass and obesity associated protein FTO. In this report, we describe the first functional characterization of mouse Alkbh7. We show that the Alkbh7 protein is located in the mitochondrial matrix and that an Alkbh7 deletion dramatically increases body weight and body fat. Our data indicate that Alkbh7, directly or indirectly, facilitates the utilization of short-chain fatty acids, which we propose is the likely cause for the obesity phenotype observed in the Alkbh7(-/-) mice. Collectively, our data provide the first direct demonstration that murine Alkbh7 is a mitochondrial resident protein involved in fatty acid metabolism and the development of obesity.
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Affiliation(s)
- Anja Solberg
- Clinic for Diagnostics and Intervention and Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway
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24
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Couvé S, Ishchenko AA, Fedorova OS, Ramanculov EM, Laval J, Saparbaev M. Direct DNA Lesion Reversal and Excision Repair in Escherichia coli. EcoSal Plus 2013; 5. [PMID: 26442931 DOI: 10.1128/ecosalplus.7.2.4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Indexed: 06/05/2023]
Abstract
Cellular DNA is constantly challenged by various endogenous and exogenous genotoxic factors that inevitably lead to DNA damage: structural and chemical modifications of primary DNA sequence. These DNA lesions are either cytotoxic, because they block DNA replication and transcription, or mutagenic due to the miscoding nature of the DNA modifications, or both, and are believed to contribute to cell lethality and mutagenesis. Studies on DNA repair in Escherichia coli spearheaded formulation of principal strategies to counteract DNA damage and mutagenesis, such as: direct lesion reversal, DNA excision repair, mismatch and recombinational repair and genotoxic stress signalling pathways. These DNA repair pathways are universal among cellular organisms. Mechanistic principles used for each repair strategies are fundamentally different. Direct lesion reversal removes DNA damage without need for excision and de novo DNA synthesis, whereas DNA excision repair that includes pathways such as base excision, nucleotide excision, alternative excision and mismatch repair, proceeds through phosphodiester bond breakage, de novo DNA synthesis and ligation. Cell signalling systems, such as adaptive and oxidative stress responses, although not DNA repair pathways per se, are nevertheless essential to counteract DNA damage and mutagenesis. The present review focuses on the nature of DNA damage, direct lesion reversal, DNA excision repair pathways and adaptive and oxidative stress responses in E. coli.
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25
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Nay SL, Lee DH, Bates SE, O'Connor TR. Alkbh2 protects against lethality and mutation in primary mouse embryonic fibroblasts. DNA Repair (Amst) 2012; 11:502-10. [PMID: 22429847 DOI: 10.1016/j.dnarep.2012.02.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 02/14/2012] [Accepted: 02/23/2012] [Indexed: 12/11/2022]
Abstract
Alkylating agents modify DNA and RNA forming adducts that disrupt replication and transcription, trigger cell cycle checkpoints and/or initiate apoptosis. If left unrepaired, some of the damage can be cytotoxic and/or mutagenic. In Escherichia coli, the alkylation repair protein B (AlkB) provides one form of resistance to alkylating agents by eliminating mainly 1-methyladenine and 3-methylcytosine, thereby increasing survival and preventing mutation. To examine the biological role of the mammalian AlkB homologs Alkbh2 and Alkbh3, which both have similar enzymatic activities to that of AlkB, we evaluated the survival and mutagenesis of primary Big Blue mouse embryonic fibroblasts (MEFs) that had targeted deletions in the Alkbh2 or Alkbh3 genes. Both Alkbh2- and Alkbh3-deficient MEFs were ∼2-fold more sensitive to methyl methanesulfonate (MMS) induced cytotoxicity compared to the wild type control cells. Spontaneous mutant frequencies were similar for the wild type, Alkbh2-/- and Alkbh3-/- MEFs (average--1.3×10(-5)). However, despite the similar survival of the two mutant MEFs after MMS treatment, only the Alkbh2-deficient MEFs showed a statistically significant increase in mutant frequency compared to wild type MEFs after MMS treatment. Therefore, although both Alkbh2 and Alkbh3 can protect against MMS-induced cell death, only Alkbh2 shows statistically significant protection of MEF DNA against mutations following treatment with this exogenous methylating agent.
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Affiliation(s)
- Stephanie L Nay
- Biology Division, Beckman Research Institute, Irell and Manella Graduate School of Biological Sciences, City of Hope National Medical Center, 1450 East Duarte Road, Duarte, CA 91010, United States
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26
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Affiliation(s)
- M. V. Kovalchuk
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
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27
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Morita R, Nakane S, Shimada A, Inoue M, Iino H, Wakamatsu T, Fukui K, Nakagawa N, Masui R, Kuramitsu S. Molecular mechanisms of the whole DNA repair system: a comparison of bacterial and eukaryotic systems. J Nucleic Acids 2010; 2010:179594. [PMID: 20981145 PMCID: PMC2957137 DOI: 10.4061/2010/179594] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 07/27/2010] [Indexed: 11/20/2022] Open
Abstract
DNA is subjected to many endogenous and exogenous damages. All organisms have developed a complex network of DNA repair mechanisms. A variety of different DNA repair pathways have been reported: direct reversal, base excision repair, nucleotide excision repair, mismatch repair, and recombination repair pathways. Recent studies of the fundamental mechanisms for DNA repair processes have revealed a complexity beyond that initially expected, with inter- and intrapathway complementation as well as functional interactions between proteins involved in repair pathways. In this paper we give a broad overview of the whole DNA repair system and focus on the molecular basis of the repair machineries, particularly in Thermus thermophilus HB8.
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Affiliation(s)
- Rihito Morita
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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28
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Westbye MP, Feyzi E, Aas PA, Vågbø CB, Talstad VA, Kavli B, Hagen L, Sundheim O, Akbari M, Liabakk NB, Slupphaug G, Otterlei M, Krokan HE. Human AlkB homolog 1 is a mitochondrial protein that demethylates 3-methylcytosine in DNA and RNA. J Biol Chem 2008; 283:25046-56. [PMID: 18603530 DOI: 10.1074/jbc.m803776200] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli AlkB protein and human homologs hABH2 and hABH3 are 2-oxoglutarate (2OG)/Fe(II)-dependent DNA/RNA demethylases that repair 1-methyladenine and 3-methylcytosine residues. Surprisingly, hABH1, which displays the strongest homology to AlkB, failed to show repair activity in two independent studies. Here, we show that hABH1 is a mitochondrial protein, as demonstrated using fluorescent fusion protein expression, immunocytochemistry, and Western blot analysis. A fraction is apparently nuclear and this fraction increases strongly if the fluorescent tag is placed at the N-terminal end of the protein, thus interfering with mitochondrial targeting. Molecular modeling of hABH1 based upon the sequence and known structures of AlkB and hABH3 suggested an active site almost identical to these enzymes. hABH1 decarboxylates 2OG in the absence of a prime substrate, and the activity is stimulated by methylated nucleotides. Employing three different methods we demonstrate that hABH1 demethylates 3-methylcytosine in single-stranded DNA and RNA in vitro. Site-specific mutagenesis confirmed that the putative Fe(II) and 2OG binding residues are essential for activity. In conclusion, hABH1 is a functional mitochondrial AlkB homolog that repairs 3-methylcytosine in single-stranded DNA and RNA.
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Affiliation(s)
- Marianne Pedersen Westbye
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway
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29
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Tsujikawa K, Koike K, Kitae K, Shinkawa A, Arima H, Suzuki T, Tsuchiya M, Makino Y, Furukawa T, Konishi N, Yamamoto H. Expression and sub-cellular localization of human ABH family molecules. J Cell Mol Med 2008; 11:1105-16. [PMID: 17979886 PMCID: PMC4401260 DOI: 10.1111/j.1582-4934.2007.00094.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
AlkB is an Escherichia coli protein that catalyses the oxidative demethylation of 1-methyladenine and 3-methylcytosine in DNA and RNA. The enzyme activity of AlkB is dependent on a 2-oxoglutarate- and Fe(II)-dependent (2OG-Fe[II]) oxygenase domain. Human AlkB homologues (hABH), hABH1, hABH2 and hABH3, which also possess the 2OG-Fe(II) oxygenase domain, have previously been identified. Recent bioinformatics analysis suggests the existence of an additional five ABH genes in humans. In this study, we identified the hABH4–hABH7 mRNAs and determined their expression in human tissues. Moreover, an hABH2 splice variant lacking the 2OG-Fe(II) oxygenase domain and a new gene, hABH8, were cloned from testis cDNA. hABH8 possesses not only the 2OG-Fe(II) oxygenase domain but both an RNA-binding motif and a methyl-transferase domain. mRNA of the eight hABH molecules was detected in the 16 normal human tissues examined. The sub-cellular localization of EmGFP-hABH8 was restricted to the cytoplasm. EmGFP-hABH1, 3, 4, 6 and 7 were localized in both the cytoplasm and nuclei. Interestingly, the EmGFP-hABH2 splice variant localized in nucleoplasm with a dot-like pattern. In some HeLa cells transfected with EmGFP-hABH5, dot-like fluorescence was also detected in the cytoplasm. These observations provide important information for the future annotation of the hABH family of molecules.
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Affiliation(s)
- Kazutake Tsujikawa
- Department of Immunology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
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30
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Falnes PØ, Klungland A, Alseth I. Repair of methyl lesions in DNA and RNA by oxidative demethylation. Neuroscience 2006; 145:1222-32. [PMID: 17175108 DOI: 10.1016/j.neuroscience.2006.11.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 10/27/2006] [Accepted: 11/01/2006] [Indexed: 11/29/2022]
Abstract
It was established several decades ago that it is crucial for all organisms to repair their DNA to maintain genome integrity and numerous proteins are dedicated to this purpose. However, it is becoming increasingly clear that it is also important to prevent and repair lesions in the macromolecules encoded by the DNA, i.e. RNA and protein. Many neurological disorders such as Alzheimer's disease and Parkinson's disease are associated with the aggregation of defective, misfolded proteins, and several mechanisms exist to prevent such aggregation, both through direct protein repair and through the elimination and repair of faulty or damaged RNAs. A few years ago, it was discovered that the E. coli AlkB protein represented an iron and 2-oxoglutarate dependent oxygenase capable of repairing methyl lesions in DNA by a novel mechanism, termed oxidative demethylation. Furthermore, it was found that both human and bacterial AlkB proteins were able to demethylate lesions also in RNA, thus representing the first example of RNA repair. In the present review, recent findings on the AlkB mechanism, as well as on RNA damage in general, will be discussed.
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Affiliation(s)
- P Ø Falnes
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway.
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Ringvoll J, Nordstrand LM, Vågbø CB, Talstad V, Reite K, Aas PA, Lauritzen KH, Liabakk NB, Bjørk A, Doughty RW, Falnes PØ, Krokan HE, Klungland A. Repair deficient mice reveal mABH2 as the primary oxidative demethylase for repairing 1meA and 3meC lesions in DNA. EMBO J 2006; 25:2189-98. [PMID: 16642038 PMCID: PMC1462979 DOI: 10.1038/sj.emboj.7601109] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Accepted: 03/31/2006] [Indexed: 11/09/2022] Open
Abstract
Two human homologs of the Escherichia coli AlkB protein, denoted hABH2 and hABH3, were recently shown to directly reverse 1-methyladenine (1meA) and 3-methylcytosine (3meC) damages in DNA. We demonstrate that mice lacking functional mABH2 or mABH3 genes, or both, are viable and without overt phenotypes. Neither were histopathological changes observed in the gene-targeted mice. However, in the absence of any exogenous exposure to methylating agents, mice lacking mABH2, but not mABH3 defective mice, accumulate significant levels of 1meA in the genome, suggesting the presence of a biologically relevant endogenous source of methylating agent. Furthermore, embryonal fibroblasts from mABH2-deficient mice are unable to remove methyl methane sulfate (MMS)-induced 1meA from genomic DNA and display increased cytotoxicity after MMS exposure. In agreement with these results, we found that in vitro repair of 1meA and 3meC in double-stranded DNA by nuclear extracts depended primarily, if not solely, on mABH2. Our data suggest that mABH2 and mABH3 have different roles in the defense against alkylating agents.
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Affiliation(s)
- Jeanette Ringvoll
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
| | - Line M Nordstrand
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
| | - Cathrine B Vågbø
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim
| | - Vivi Talstad
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim
| | - Karen Reite
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
| | - Per Arne Aas
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim
| | - Knut H Lauritzen
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
| | - Nina Beate Liabakk
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim
| | - Alexandra Bjørk
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
| | | | - Pål Ø Falnes
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | - Hans E Krokan
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim
| | - Arne Klungland
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, 0027 Oslo, Norway. Tel.: +47 23074072; Fax: +47 23074061; E-mail:
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Mishina Y, He C. Oxidative dealkylation DNA repair mediated by the mononuclear non-heme iron AlkB proteins. J Inorg Biochem 2006; 100:670-8. [PMID: 16469386 PMCID: PMC2386269 DOI: 10.1016/j.jinorgbio.2005.12.018] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Accepted: 12/13/2005] [Indexed: 11/19/2022]
Abstract
DNA can be damaged by various intracellular and environmental alkylating agents to produce alkylation base lesions. These base damages, if not repaired promptly, may cause genetic changes that lead to diseases such as cancer. Recently, it was discovered that some of the alkylation DNA base damage can be directly removed by a family of proteins called the AlkB proteins that utilize a mononuclear non-heme iron(II) and alpha-ketoglutarate as cofactor and cosubstrate. These proteins activate dioxygen and perform an unprecedented oxidative dealkylation of the alkyl adducts on DNA heteroatoms. This review summarizes the discovery of this activity and the recent research advances in studying this unique DNA repair pathway. The focus is placed on the chemical mechanism and function of these proteins.
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Affiliation(s)
| | - Chuan He
- Corresponding author. Tel.: +1 773 702 5061; fax: +1 773 702 0805. E-mail address: (C. He)
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Affiliation(s)
- Yukiko Mishina
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637
| | - Erica M. Duguid
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637
| | - Chuan He
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637
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Konishi N, Nakamura M, Ishida E, Shimada K, Mitsui E, Yoshikawa R, Yamamoto H, Tsujikawa K. High expression of a new marker PCA-1 in human prostate carcinoma. Clin Cancer Res 2005; 11:5090-7. [PMID: 16033822 DOI: 10.1158/1078-0432.ccr-05-0195] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Identifying the genetic factors involved in prostate carcinogenesis is critical. Novel cancer-specific markers aid in early detection, in differentiating between cancer and nonmalignant disorders, and in monitoring clinical of prostate disease. We therefore examined differential gene displays in an attempt to identify genes that may be involved in prostate carcinogenesis. EXPERIMENTAL DESIGN Applying fluorescent differential display analysis to human prostate carcinomas, we have identified and cloned several cDNA transcripts. Antisera were raised against synthetic peptides and used in Western blot and immunohistochemical analyses. The mRNAs were also analyzed by real-time reverse transcription-PCR. For functional analysis, we assessed methylmethane sulfonate (MMS)-induced toxicity in COS-7 cells after cDNA transfection. RESULTS We identified a gene, designated prostate cancer antigen-1 (pca-1), which shows high mRNA expression in prostate carcinoma. Database analysis of the deduced amino acid sequence of PCA-1 indicated high similarity to Escherichia coli AlkB, a DNA alkylation damage repair enzyme. By immunohistochemical analysis, PCA-1 was expressed in a high number of both prostate carcinoma samples and in the atypical cells within high-grade prostatic intraepithelial neoplasias but not in benign prostatic hyperplasia or normal adjacent tissues. PCA-1-transfected COS-7 cells further showed resistance against MMS-induced cell death. CONCLUSIONS These findings suggest that PCA-1 could be a useful diagnostic marker. Furthermore, because this human counterpart of AlkB exhibits a protective function against alkylation damage in mammalian cells, PCA-1 may also serve as a therapeutic target molecule for prostate cancer.
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Affiliation(s)
- Noboru Konishi
- Department of Pathology, Nara Medical University School of Medicine, Kashihara, Nara, Japan.
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Lee DH, Jin SG, Cai S, Chen Y, Pfeifer GP, O'Connor TR. Repair of methylation damage in DNA and RNA by mammalian AlkB homologues. J Biol Chem 2005; 280:39448-59. [PMID: 16174769 DOI: 10.1074/jbc.m509881200] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human and Escherichia coli derivatives of AlkB enzymes remove methyl groups from 1-methyladenine and 3-methylcytosine in nucleic acids via an oxidative mechanism that releases the methyl group as formaldehyde. In this report, we demonstrate that the mouse homologues of the alpha-ketoglutarate Fe(II) oxygen-dependent enzymes mAbh2 and Abh3 have activities comparable to those of their human counterparts. The mAbh2 and mAbh3 release modified bases from both DNA and RNA. Comparison of the activities of the homogenous ABH2 and ABH3 enzymes demonstrate that these activities are shared by both sets of enzymes. An assay for the detection of alpha-ketoglutarate Fe(II) dioxygenase activity using an oligodeoxyribonucleotide with a unique modification shows activity for all four enzymes studied and a loss of activity for eight mutant proteins. Steady-state kinetics for removal of methyl groups from DNA substrates indicates that the reactions of the proteins are close to the diffusion limit. Moreover, mAbh2 or mAbh3 activity increases survival in a strain defective in alkB. The mRNAs of AHB2 and ABH3 are expressed most in testis for ABH2 and ABH3, whereas expression of the homologous mouse genes is different. The mAbh3 is strongly expressed in testis, whereas highest expression of mAbh2 is in heart. Other purified human AlkB homologue proteins ABH4, ABH6, and ABH7 do not manifest activity. The demonstration of mAbh2 and mAbh3 activities and their distributions provide data on these mammalian homologues of AlkB that can be used in animal studies.
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Affiliation(s)
- Dong-Hyun Lee
- Biology Division, Beckman Research Institute, City of Hope National Medical Center, Duarte, California 91010, USA
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Drabløs F, Feyzi E, Aas PA, Vaagbø CB, Kavli B, Bratlie MS, Peña-Diaz J, Otterlei M, Slupphaug G, Krokan HE. Alkylation damage in DNA and RNA--repair mechanisms and medical significance. DNA Repair (Amst) 2005; 3:1389-407. [PMID: 15380096 DOI: 10.1016/j.dnarep.2004.05.004] [Citation(s) in RCA: 443] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Indexed: 12/13/2022]
Abstract
Alkylation lesions in DNA and RNA result from endogenous compounds, environmental agents and alkylating drugs. Simple methylating agents, e.g. methylnitrosourea, tobacco-specific nitrosamines and drugs like temozolomide or streptozotocin, form adducts at N- and O-atoms in DNA bases. These lesions are mainly repaired by direct base repair, base excision repair, and to some extent by nucleotide excision repair (NER). The identified carcinogenicity of O(6)-methylguanine (O(6)-meG) is largely caused by its miscoding properties. Mutations from this lesion are prevented by O(6)-alkylG-DNA alkyltransferase (MGMT or AGT) that repairs the base in one step. However, the genotoxicity and cytotoxicity of O(6)-meG is mainly due to recognition of O(6)-meG/T (or C) mispairs by the mismatch repair system (MMR) and induction of futile repair cycles, eventually resulting in cytotoxic double-strand breaks. Therefore, inactivation of the MMR system in an AGT-defective background causes resistance to the killing effects of O(6)-alkylating agents, but not to the mutagenic effect. Bifunctional alkylating agents, such as chlorambucil or carmustine (BCNU), are commonly used anti-cancer drugs. DNA lesions caused by these agents are complex and require complex repair mechanisms. Thus, primary chloroethyl adducts at O(6)-G are repaired by AGT, while the secondary highly cytotoxic interstrand cross-links (ICLs) require nucleotide excision repair factors (e.g. XPF-ERCC1) for incision and homologous recombination to complete repair. Recently, Escherichia coli protein AlkB and human homologues were shown to be oxidative demethylases that repair cytotoxic 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) residues. Numerous AlkB homologues are found in viruses, bacteria and eukaryotes, including eight human homologues (hABH1-8). These have distinct locations in subcellular compartments and their functions are only starting to become understood. Surprisingly, AlkB and hABH3 also repair RNA. An evaluation of the biological effects of environmental mutagens, as well as understanding the mechanism of action and resistance to alkylating drugs require a detailed understanding of DNA repair processes.
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Affiliation(s)
- Finn Drabløs
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway
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Falnes PØ. Repair of 3-methylthymine and 1-methylguanine lesions by bacterial and human AlkB proteins. Nucleic Acids Res 2004; 32:6260-7. [PMID: 15576352 PMCID: PMC535673 DOI: 10.1093/nar/gkh964] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Escherichia coli AlkB protein repairs 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) lesions in DNA and RNA by oxidative demethylation, a reaction requiring ferrous iron and 2-oxoglutarate as cofactor and co-substrate, respectively. Here, we have studied the activity of AlkB proteins on 3-methylthymine (3-meT) and 1-methylguanine (1-meG), two minor lesions which are structurally analogous to 1-meA and 3-meC. AlkB as well as the human AlkB homologues, hABH2 and hABH3, were all able to demethylate 3-meT in a DNA oligonucleotide containing a single 3-meT residue. Also, 1-meG lesions introduced by chemical methylation of tRNA were efficiently removed by AlkB. Unlike 1-meA and 3-meC, nucleosides or bases corresponding to 1-meG or 3-meT did not stimulate the uncoupled, AlkB-mediated decarboxylation of 2-oxoglutarate. Our data show that 3-meT and 1-meG are repaired by AlkB, but indicate that the recognition of these substrates is different from that in the case of 1-meA and 3-meC.
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Affiliation(s)
- Pål Ø Falnes
- Department of Molecular Biosciences, University of Oslo, Postboks 1041, Blindern, 0316 Oslo, Norway.
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Abstract
Methylating agents modify DNA at many different sites, thereby producing lethal and mutagenic lesions. To remove all the main harmful base lesions, at least three types of DNA-repair activities can be used, each of which involves a different reaction mechanism. These activities include DNA-glycosylases, DNA-methyltransferases and the recently characterized DNA-dioxygenases. The Escherichia coli AlkB dioxygenase and the two human homologues, ABH2 and ABH3, represent a novel mechanism of DNA repair. They use iron-oxo intermediates to oxidize stable methylated bases in DNA and directly revert them to the unmodified form.
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Affiliation(s)
- Barbara Sedgwick
- Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Hertfordshire EN6 3LD, UK.
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Mishina Y, Lee CHJ, He C. Interaction of human and bacterial AlkB proteins with DNA as probed through chemical cross-linking studies. Nucleic Acids Res 2004; 32:1548-54. [PMID: 15004242 PMCID: PMC390304 DOI: 10.1093/nar/gkh319] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Escherichia coli AlkB protein was recently found to repair cytotoxic DNA lesions 1-methyladenine and 3-methylcytosine by using a novel iron-catalyzed oxidative demethylation mechanism. Three human homologs, ABH1, ABH2 and ABH3, have been identified, and two of them, ABH2 and ABH3, were shown to have similar repair activities to E.coli AlkB. However, ABH1 did not show any repair activity. It was suggested that ABH3 prefers single-stranded DNA and RNA substrates, whereas AlkB and ABH2 can repair damage in both single- and double-stranded DNA. We employed a chemical cross-linking approach to probe the structure and substrate preferences of AlkB and its three human homologs. The putative active site iron ligands in these proteins were mutated to cysteine residues. These mutant proteins were used to cross-link to different DNA probes bearing thiol-tethered bases. Disulfide-linked protein-DNA complexes can be trapped and analyzed by SDS-PAGE. Our results show that ABH2 and ABH3 have structural and functional similarities to E.coli AlkB. ABH3 shows preference for the single-stranded DNA probe. ABH1 failed to cross-link to the probes tested. This protein, unlike other AlkB proteins, does not seem to interact with DNA in its E.coli expressed form.
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Affiliation(s)
- Yukiko Mishina
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
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Abstract
The human genome, comprising three billion base pairs coding for 30000-40000 genes, is constantly attacked by endogenous reactive metabolites, therapeutic drugs and a plethora of environmental mutagens that impact its integrity. Thus it is obvious that the stability of the genome must be under continuous surveillance. This is accomplished by DNA repair mechanisms, which have evolved to remove or to tolerate pre-cytotoxic, pre-mutagenic and pre-clastogenic DNA lesions in an error-free, or in some cases, error-prone way. Defects in DNA repair give rise to hypersensitivity to DNA-damaging agents, accumulation of mutations in the genome and finally to the development of cancer and various metabolic disorders. The importance of DNA repair is illustrated by DNA repair deficiency and genomic instability syndromes, which are characterised by increased cancer incidence and multiple metabolic alterations. Up to 130 genes have been identified in humans that are associated with DNA repair. This review is aimed at updating our current knowledge of the various repair pathways by providing an overview of DNA-repair genes and the corresponding proteins, participating either directly in DNA repair, or in checkpoint control and signaling of DNA damage.
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Affiliation(s)
- Markus Christmann
- Division of Applied Toxicology, Institute of Toxicology, University of Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
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Kurowski MA, Bhagwat AS, Papaj G, Bujnicki JM. Phylogenomic identification of five new human homologs of the DNA repair enzyme AlkB. BMC Genomics 2003; 4:48. [PMID: 14667252 PMCID: PMC317286 DOI: 10.1186/1471-2164-4-48] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Accepted: 12/10/2003] [Indexed: 11/10/2022] Open
Abstract
Background Combination of biochemical and bioinformatic analyses led to the discovery of oxidative demethylation – a novel DNA repair mechanism catalyzed by the Escherichia coli AlkB protein and its two human homologs, hABH2 and hABH3. This discovery was based on the prediction made by Aravind and Koonin that AlkB is a member of the 2OG-Fe2+ oxygenase superfamily. Results In this article, we report identification and sequence analysis of five human members of the (2OG-Fe2+) oxygenase superfamily designated here as hABH4 through hABH8. These experimentally uncharacterized and poorly annotated genes were not associated with the AlkB family in any database, but are predicted here to be phylogenetically and functionally related to the AlkB family (and specifically to the lineage that groups together hABH2 and hABH3) rather than to any other oxygenase family. Our analysis reveals the history of ABH gene duplications in the evolution of vertebrate genomes. Conclusions We hypothesize that hABH 4–8 could either be back-up enzymes for hABH1-3 or may code for novel DNA or RNA repair activities. For example, enzymes that can dealkylate N3-methylpurines or N7-methylpurines in DNA have not been described. Our analysis will guide experimental confirmation of these novel human putative DNA repair enzymes.
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Affiliation(s)
- Michal A Kurowski
- Bioinformatics Laboratory, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
| | - Ashok S Bhagwat
- Department of Chemistry, Wayne State University, Detroit, MI 48202, U.S.A
| | - Grzegorz Papaj
- Bioinformatics Laboratory, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
| | - Janusz M Bujnicki
- Bioinformatics Laboratory, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
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Welford RWD, Schlemminger I, McNeill LA, Hewitson KS, Schofield CJ. The selectivity and inhibition of AlkB. J Biol Chem 2003; 278:10157-61. [PMID: 12517755 DOI: 10.1074/jbc.m211058200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AlkB is one of four proteins involved in the adaptive response to DNA alkylation damage in Escherichia coli and is highly conserved from bacteria to humans. Recent analyses have verified the prediction that AlkB is a member of the Fe(II) and 2-oxoglutarate (2OG)-dependent oxygenase family of enzymes. AlkB mediates repair of methylated DNA by direct demethylation of 1-methyladenine and 3-methylcytosine lesions. Other members of the Fe(II) and 2OG-dependent oxygenase family, including those involved in the hypoxic response, are targets for therapeutic intervention. Assays measuring 2OG turnover were used to investigate the selectivity of AlkB. 1-Methyladenosine, 1-methyl-2'-deoxyadenosine, 3-methylcytidine, and 3-methyl-2'-deoxycytidine all stimulated 2OG turnover by AlkB but were not demethylated indicating an uncoupling of 2OG and prime substrate oxidation and that oligomeric DNA is required for hydroxylation and subsequent demethylation. In contrast the equivalent unmethylated nucleosides did not stimulate 2OG turnover indicating that the presence of a methyl group in the substrate is important in initiating oxidation of 2OG. Stimulation of 2OG turnover by 1-methyladenosine was highly dependent on the presence of a reducing agent, ascorbate or dithiothreitol. Following the observation that AlkB is inhibited by high concentrations of 2OG, analogues of 2OG, including 2-mercaptoglutarate, were found to specifically inhibit AlkB. The flavonoid quercetin inhibits both AlkB and the 2OG oxygenase factor-inhibiting hypoxia-inducible factor (FIH) in vitro. FIH inhibition by quercetin occurs in the presence of excess iron indicating a specific interaction, while the inhibition of AlkB by quercetin is, predominantly, due to nonspecific iron chelation.
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Affiliation(s)
- Richard W D Welford
- Dyson Perrins Laboratory and The Oxford Centre for Molecular Sciences, United Kingdom
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Aas PA, Otterlei M, Falnes PO, Vågbø CB, Skorpen F, Akbari M, Sundheim O, Bjørås M, Slupphaug G, Seeberg E, Krokan HE. Human and bacterial oxidative demethylases repair alkylation damage in both RNA and DNA. Nature 2003; 421:859-63. [PMID: 12594517 DOI: 10.1038/nature01363] [Citation(s) in RCA: 469] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2002] [Accepted: 11/28/2002] [Indexed: 11/09/2022]
Abstract
Repair of DNA damage is essential for maintaining genome integrity, and repair deficiencies in mammals are associated with cancer, neurological disease and developmental defects. Alkylation damage in DNA is repaired by at least three different mechanisms, including damage reversal by oxidative demethylation of 1-methyladenine and 3-methylcytosine by Escherichia coli AlkB. By contrast, little is known about consequences and cellular handling of alkylation damage to RNA. Here we show that two human AlkB homologues, hABH2 and hABH3, also are oxidative DNA demethylases and that AlkB and hABH3, but not hABH2, also repair RNA. Whereas AlkB and hABH3 prefer single-stranded nucleic acids, hABH2 acts more efficiently on double-stranded DNA. In addition, AlkB and hABH3 expressed in E. coli reactivate methylated RNA bacteriophage MS2 in vivo, illustrating the biological relevance of this repair activity and establishing RNA repair as a potentially important defence mechanism in living cells. The different catalytic properties and the different subnuclear localization patterns shown by the human homologues indicate that hABH2 and hABH3 have distinct roles in the cellular response to alkylation damage.
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Affiliation(s)
- Per Arne Aas
- Institute of Cancer Research and Molecular Biology, Norwegian University of Science and Technology, N-7489 Trondheim, Norway
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Duncan T, Trewick SC, Koivisto P, Bates PA, Lindahl T, Sedgwick B. Reversal of DNA alkylation damage by two human dioxygenases. Proc Natl Acad Sci U S A 2002; 99:16660-5. [PMID: 12486230 PMCID: PMC139200 DOI: 10.1073/pnas.262589799] [Citation(s) in RCA: 297] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2002] [Indexed: 11/18/2022] Open
Abstract
The Escherichia coli AlkB protein protects against the cytotoxicity of methylating agents by repair of the DNA lesions 1-methyladenine and 3-methylcytosine, which are generated in single-stranded stretches of DNA. AlkB is an alpha-ketoglutarate- and Fe(II)-dependent dioxygenase that oxidizes the relevant methyl groups and releases them as formaldehyde. Here, we identify two human AlkB homologs, ABH2 and ABH3, by sequence and fold similarity, functional assays, and complementation of the E. coli alkB mutant phenotype. The levels of their mRNAs do not appear to correlate with cell proliferation but tissue distributions are different. Both enzymes remove 1-methyladenine and 3-methylcytosine from methylated polynucleotides in an alpha-ketoglutarate-dependent reaction, and act by direct damage reversal with the regeneration of the unsubstituted bases. AlkB, ABH2, and ABH3 can also repair 1-ethyladenine residues in DNA with the release of acetaldehyde.
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Affiliation(s)
- Tod Duncan
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, United Kingdom
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46
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Abstract
Recent work has uncovered a novel DNA repair enzyme: the AlkB protein of Escherichia coli, which oxidises the methyl groups of 1-methyladenine and 3-methylcytosine to hydroxymethyl moieties; the oxidised groups are subsequently released as formaldehyde, regenerating the unmodified bases.
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Affiliation(s)
- Josef Jiricny
- Institute of Medical Radiobiology of the University of Zürich and the Paul Scherrer Institute, August Forel-Strasse 7, CH-8008 Zürich, Switzerland.
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47
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Margison G. A new damage limitation exercise: ironing (Fe(II)) out minor DNA methylation lesions. DNA Repair (Amst) 2002; 1:1057-61. [PMID: 12531015 DOI: 10.1016/s1568-7864(02)00169-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Geoff Margison
- Cancer Research UK Carcinogenesis Group, Paterson Institute for Cancer Research, Christie Hospital Trust, Manchester, M20 4BX, UK.
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Erez N, Milyavsky M, Goldfinger N, Peles E, Gudkov AV, Rotter V. Falkor, a novel cell growth regulator isolated by a functional genetic screen. Oncogene 2002; 21:6713-21. [PMID: 12360397 DOI: 10.1038/sj.onc.1205867] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2001] [Revised: 06/08/2002] [Accepted: 07/15/2002] [Indexed: 11/08/2022]
Abstract
A novel cell growth regulator, named Falkor, was identified using a functional approach to mammalian gene cloning, the Genetic Supressor Elements (GSE) method. In this screen, expression of the C-terminal domain of Falkor conferred cells with resistance to cisplatin-induced growth arrest. Expression of the C-terminus of Falkor, but not of the full-length protein, enhanced cell growth both following genotoxic stress and under normal conditions suggesting a general role for this protein in cell growth control. This effect of the C-terminus fragment was abrogated by over-expression of the full-length Falkor, suggesting that the fragment counteracts the function of the full-length protein. Falkor is encoded by a 2-kb mRNA which is present at different levels in various tissues, and is localized in the nucleus of cells. The C-terminal domain of Falkor, isolated from the GSE library, has significant homology to a known human and rat cell growth regulator, SM-20, and to the C. elegans protein EGL-9, recently shown to modify the Hypoxia Inducible Factor-1alpha. The homology suggests that these proteins share a functional domain that is conserved among a family of growth regulation proteins.
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Affiliation(s)
- Neta Erez
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel 76100
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Trewick SC, Henshaw TF, Hausinger RP, Lindahl T, Sedgwick B. Oxidative demethylation by Escherichia coli AlkB directly reverts DNA base damage. Nature 2002; 419:174-8. [PMID: 12226667 DOI: 10.1038/nature00908] [Citation(s) in RCA: 566] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Methylating agents generate cytotoxic and mutagenic DNA damage. Cells use 3-methyladenine-DNA glycosylases to excise some methylated bases from DNA, and suicidal O(6)-methylguanine-DNA methyltransferases to transfer alkyl groups from other lesions onto a cysteine residue. Here we report that the highly conserved AlkB protein repairs DNA alkylation damage by means of an unprecedented mechanism. AlkB has no detectable nuclease, DNA glycosylase or methyltransferase activity; however, Escherichia coli alkB mutants are defective in processing methylation damage generated in single-stranded DNA. Theoretical protein fold recognition had suggested that AlkB resembles the Fe(ii)- and alpha-ketoglutarate-dependent dioxygenases, which use iron-oxo intermediates to oxidize chemically inert compounds. We show here that purified AlkB repairs the cytotoxic lesions 1-methyladenine and 3-methylcytosine in single- and double-stranded DNA in a reaction that is dependent on oxygen, alpha-ketoglutarate and Fe(ii). The AlkB enzyme couples oxidative decarboxylation of alpha-ketoglutarate to the hydroxylation of these methylated bases in DNA, resulting in direct reversion to the unmodified base and the release of formaldehyde.
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Affiliation(s)
- Sarah C Trewick
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
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Falnes PØ, Johansen RF, Seeberg E. AlkB-mediated oxidative demethylation reverses DNA damage in Escherichia coli. Nature 2002; 419:178-82. [PMID: 12226668 DOI: 10.1038/nature01048] [Citation(s) in RCA: 481] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The bacterial AlkB protein is known to be involved in cellular recovery from alkylation damage; however, the function of this protein remains unknown. AlkB homologues have been identified in several organisms, including humans, and a recent sequence alignment study has suggested that these proteins may belong to a superfamily of 2-oxoglutarate-dependent and iron-dependent oxygenases (2OG-Fe(ii)-oxygenases). Here we show that AlkB from Escherichia coli is indeed a 2-oxoglutarate-dependent and iron-dependent DNA repair enzyme that releases replication blocks in alkylated DNA by a mechanism involving oxidative demethylation of 1-methyladenine residues. This mechanism represents a new pathway for DNA repair and the third type of DNA damage reversal mechanism so far discovered.
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Affiliation(s)
- Pål Ø Falnes
- Centre for Molecular Biology and Neuroscience, and Institute of Medical Microbiology, University of Oslo, National Hospital, 0027 Oslo, Norway.
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