1
|
Bröhm A, Elsawy H, Rathert P, Kudithipudi S, Schoch T, Schuhmacher MK, Weirich S, Jeltsch A. Somatic Cancer Mutations in the SUV420H1 Protein Lysine Methyltransferase Modulate Its Catalytic Activity. J Mol Biol 2019; 431:3068-3080. [PMID: 31255706 DOI: 10.1016/j.jmb.2019.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/19/2019] [Accepted: 06/21/2019] [Indexed: 01/16/2023]
Abstract
SUV420H1 is a protein lysine methyltransferase that introduces di- and trimethylation of H4K20 and is frequently mutated in human cancers. We investigated the functional effects of eight somatic cancer mutations on SUV420H1 activity in vitro and in cells. One group of mutations (S255F, K258E, A269V) caused a reduction of the catalytic activity on peptide and nucleosome substrates. The mutated amino acids have putative roles in AdoMet binding and recognition of H4 residue D24. Group 2 mutations (E238V, D249N, E320K) caused a reduction of activity on peptide substrates, which was partially recovered when using nucleosomal substrates. The corresponding residues could have direct or indirect roles in peptide and AdoMet binding, but the effects of the mutations can be overcome by additional interactions between SUV420H1 and the nucleosome substrate. The third group of mutations (S283L, S304Y) showed enhanced activity with peptide substrates when compared with nucleosomal substrates, suggesting that these residues are involved in nucleosomal interaction or allosteric activation of SUV420H1 after nucleosome binding. Group 2 and 3 mutants highlight the role of nucleosomal contacts for SUV420H1 regulation in agreement with the high activity of this enzyme on nucleosomal substrates. Strikingly, seven of the somatic cancer mutations studied here led to a reduction of the catalytic activity of SUV420H1 in cells, suggesting that SUV420H1 activity might have a tumor suppressive function. This could be explained by the role of H4K20me2/3 in DNA repair, suggesting that loss or reduction of SUV420H1 activity could contribute to a mutator phenotype in cancer cells.
Collapse
Affiliation(s)
- Alexander Bröhm
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany
| | - Hany Elsawy
- Department of Chemistry, Faculty of Science, Tanta University, 31527 Tanta, El-Gharbia, Egypt
| | - Philipp Rathert
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany
| | - Srikanth Kudithipudi
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany
| | - Tabea Schoch
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany
| | - Maren Kirstin Schuhmacher
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany
| | - Sara Weirich
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany
| | - Albert Jeltsch
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569 Stuttgart, Germany.
| |
Collapse
|
2
|
Epsilon-Globin HBE1 Enhances Radiotherapy Resistance by Down-Regulating BCL11A in Colorectal Cancer Cells. Cancers (Basel) 2019; 11:cancers11040498. [PMID: 30965648 PMCID: PMC6521047 DOI: 10.3390/cancers11040498] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 12/28/2022] Open
Abstract
Resistance to radiotherapy is considered an important obstacle in the treatment of colorectal cancer. However, the mechanisms that enable tumor cells to tolerate the effects of radiation remain unclear. Moreover, radiotherapy causes accumulated mutations in transcription factors, which can lead to changes in gene expression and radiosensitivity. This phenomenon reduces the effectiveness of radiation therapy towards cancer cells. In the present study, radiation-resistant (RR) cancer cells were established by sequential radiation exposure, and hemoglobin subunit epsilon 1 (HBE1) was identified as a candidate radiation resistance-associated protein based on RNA-sequencing analysis. Then, compared to radiosensitive (RS) cell lines, the overexpression of HBE1 in RR cell lines was used to measure various forms of radiation-induced cellular damage. Consequently, HBE1-overexpressing cell lines were found to exhibit decreased radiation-induced intracellular reactive oxygen species (ROS) production and cell mortality. Conversely, HBE1 deficiency in RR cell lines increased intracellular ROS production, G2/M arrest, and apoptosis, and decreased clonogenic survival rate. These effects were reversed by the ROS scavenger N-acetyl cysteine. Moreover, HBE1 overexpression was found to attenuate radiation-induced endoplasmic reticulum stress and apoptosis via an inositol-requiring enzyme 1(IRE1)-Jun amino-terminal kinase (JNK) signaling pathway. In addition, increased HBE1 expression induced by γ-irradiation in RS cells attenuated expression of the transcriptional regulator BCL11A, whereas its depletion in RR cells increased BCL11A expression. Collectively, these observations indicate that the expression of HBE1 during radiotherapy might potentiate the survival of radiation-exposed colorectal cancer cells.
Collapse
|
3
|
Wang Y, Wang Y, Ma L, Nie M, Ju J, Liu M, Deng Y, Yao B, Gui T, Li X, Guo C, Ma C, Tan R, Zhao Q. Heterochromatin Protein 1γ Is a Novel Epigenetic Repressor of Human Embryonic ϵ-Globin Gene Expression. J Biol Chem 2017; 292:4811-4817. [PMID: 28154185 DOI: 10.1074/jbc.m116.768515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/27/2017] [Indexed: 11/06/2022] Open
Abstract
Production of hemoglobin during development is tightly regulated. For example, expression from the human β-globin gene locus, comprising β-, δ-, ϵ-, and γ-globin genes, switches from ϵ-globin to γ-globin during embryonic development and then from γ-globin to β-globin after birth. Expression of human ϵ-globin in mice has been shown to ameliorate anemia caused by β-globin mutations, including those causing β-thalassemia and sickle cell disease, raising the prospect that reactivation of ϵ-globin expression could be used in managing these conditions in humans. Although the human globin genes are known to be regulated by a variety of multiprotein complexes containing enzymes that catalyze epigenetic modifications, the exact mechanisms controlling ϵ-globin gene silencing remain elusive. Here we found that the heterochromatin protein HP1γ, a multifunctional chromatin- and DNA-binding protein with roles in transcriptional activation and elongation, represses ϵ-globin expression by interacting with a histone-modifying enzyme, lysine methyltransferase SUV4-20h2. Silencing of HP1γ expression markedly decreased repressive histone marks and the multimethylation of histone H3 lysine 9 and H4 lysine 20, leading to a significant decrease in DNA methylation at the proximal promoter of the ϵ-globin gene and greatly increased ϵ-globin expression. In addition, using chromatin immunoprecipitation, we showed that SUV4-20h2 facilitates the deposition of HP1γ on the ϵ-globin-proximal promoter. Thus, these data indicate that HP1γ is a novel epigenetic repressor of ϵ-globin gene expression and provide a potential strategy for targeted therapies for β-thalassemia and sickle cell disease.
Collapse
Affiliation(s)
- Yadong Wang
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Ying Wang
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Lingling Ma
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Min Nie
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Junyi Ju
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Ming Liu
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Yexuan Deng
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Bing Yao
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Tao Gui
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Xinyu Li
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Chan Guo
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Chi Ma
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Renxiang Tan
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Quan Zhao
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| |
Collapse
|