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Yusoff NA, Abd Hamid Z, Chow PW, Shuib S, Taib IS, Budin SB. Chromosomal Analysis in Lineage-Specific Mouse Hematopoietic Stem Cells and Progenitors. Methods Mol Biol 2024; 2736:65-76. [PMID: 36749486 DOI: 10.1007/7651_2022_477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Hematopoiesis is maintained throughout life from the hematopoietic stem cell niche in which hematopoietic stem cells and lineage-specific hematopoietic progenitors (HSPCs) reside and regulate hematopoiesis. Meanwhile, HSPCs behavior is modulated by both cell intrinsic (e.g., transcriptional factors) and cell extrinsic (e.g., cytokines) factors. Dysregulation of these factors can alter HSPCs function, leading to disrupted hematopoiesis, cellular changes, and subsequent hematological diseases and malignancies. Moreover, it has been reported that chromosomal aberration (CA) in HSPCs following exposure to carcinogenic or genotoxic agents can initiate leukemia stem cells (LSCs) formation which lays a fundamental mechanism in leukemogenesis. Despite reported studies concerning the chromosomal integrity in HSPCs, CA analysis in lineage-specific HSPCs remains scarce. This indicates a need for a laboratory technique that allows the study of CA in specific HSPCs subpopulations comprising differential hematopoietic lineages. Thus, this chapter focuses on the structural (clastogenicity) and numerical (aneugenicity) form of CA analysis in lineage-specific HSPCs comprised of myeloid, erythroid and lymphoid lineages.In this protocol, we describe how to perform CA analysis in lineage-specific HSPCs derived from freshly isolated mouse bone marrow cells (MBMCs) using the combined techniques of colony-forming unit (CFU) and karyotyping. Prior to CA analysis, lineage-specific HSPCs for myeloid, erythroid, and lymphoid were enriched through colony-forming unit (CFU) assay. CFU assay assesses the proliferative ability and differentiation potential of an individual HSPC within a sample. About 6 to 14 days of cultures are required depending on the type of HSPCs lineage. The optimal duration is crucial to achieve sufficient colony growth that is needed for accurate CFU analysis via morphological identification and colony counting. Then, the CA focusing on clastogenicity and aneugenicity anomalies in respective HSPCs lineage for myeloid, erythroid and Pre-B lymphoid were investigated. The resulted karyotypes were classified according to the types of CA known as Robertsonian (Rb) translocation, hyperploidy or complex. We believe our protocol offers a significant contribution to be utilized as a reference method for chromosomal analysis in lineage-specific HSPCs subpopulations.
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Affiliation(s)
- Nur Afizah Yusoff
- Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Zariyantey Abd Hamid
- Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
| | - Paik Wah Chow
- Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
- All Life Advance Immunology Sdn. Bhd., Petaling Jaya, Selangor, Malaysia
| | - Salwati Shuib
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Izatus Shima Taib
- Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Siti Balkis Budin
- Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
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Chow PW, Abd Hamid Z, Mathialagan RD, Rajab NF, Shuib S, Sulong S. Clastogenicity and Aneugenicity of 1,4-Benzoquinone in Different Lineages of Mouse Hematopoietic Stem/Progenitor Cells. TOXICS 2021; 9:toxics9050107. [PMID: 34065823 PMCID: PMC8150741 DOI: 10.3390/toxics9050107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 05/03/2021] [Accepted: 05/07/2021] [Indexed: 11/16/2022]
Abstract
Previous reports on hematotoxicity and leukemogenicity related to benzene exposure highlighted its adverse effects on hematopoiesis. Despite the reported findings, studies concerning the mechanism of benzene affecting chromosomal integrity in lineage-committed hematopoietic stem/progenitor cells (HSPCs) remain unclear. Here, we studied the clastogenicity and aneugenicity of benzene in lineage-committed HSPCs via karyotyping. Isolated mouse bone marrow cells (MBMCs) were exposed to the benzene metabolite 1,4-benzoquinone (1,4-BQ) at 1.25, 2.5, 5, 7, and 12 μM for 24 h, followed by karyotyping. Then, the chromosomal aberration (CA) in 1,4-BQ-exposed hematopoietic progenitor cells (HPCs) comprising myeloid, Pre-B lymphoid, and erythroid lineages were evaluated following colony-forming cell (CFC) assay. Percentage of CA, predominantly via Robertsonian translocation (Rb), was increased significantly (p < 0.05) in MBMCs and all progenitors at all concentrations. As a comparison, Pre-B lymphoid progenitor demonstrated a significantly higher percentage of CA (p < 0.05) than erythroid progenitor at 1.25, 2.5, and 7 μM as well as a significantly higher percentage (p < 0.05) than myeloid progenitor at 7 μM of 1,4-BQ. In conclusion, 1,4-BQ induced CA, particularly via Rb in both MBMCs and HPCs, notably via a lineage-dependent response. The role of lineage specificity in governing the clastogenicity and aneugenicity of 1,4-BQ deserves further investigation.
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Affiliation(s)
- Paik Wah Chow
- Biomedical Science Programme and Center for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 50300, Malaysia; (P.W.C.); (R.D.M.)
| | - Zariyantey Abd Hamid
- Biomedical Science Programme and Center for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 50300, Malaysia; (P.W.C.); (R.D.M.)
- Correspondence: ; Tel.: +60-3-9289-7196
| | - Ramya Dewi Mathialagan
- Biomedical Science Programme and Center for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 50300, Malaysia; (P.W.C.); (R.D.M.)
| | - Nor Fadilah Rajab
- Biomedical Science Programme and Center for Healthy Ageing & Wellness, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 50300, Malaysia;
| | - Salwati Shuib
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia;
| | - Sarina Sulong
- Human Genome Center, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kelantan 16150, Malaysia;
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Mathialagan RD, Abd Hamid Z, Ng QM, Rajab NF, Shuib S, Binti Abdul Razak SR. Bone Marrow Oxidative Stress and Acquired Lineage-Specific Genotoxicity in Hematopoietic Stem/Progenitor Cells Exposed to 1,4-Benzoquinone. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17165865. [PMID: 32823552 PMCID: PMC7459782 DOI: 10.3390/ijerph17165865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/05/2020] [Accepted: 08/07/2020] [Indexed: 12/23/2022]
Abstract
Hematopoietic stem/progenitor cells (HSPCs) are susceptible to benzene-induced genotoxicity. However, little is known about the mechanism of DNA damage response affecting lineage-committed progenitors for myeloid, erythroid, and lymphoid. Here, we investigated the genotoxicity of a benzene metabolite, 1,4-benzoquinone (1,4-BQ), in HSPCs using oxidative stress and lineage-directed approaches. Mouse bone marrow cells (BMCs) were exposed to 1,4-BQ (1.25–12 μM) for 24 h, followed by oxidative stress and genotoxicity assessments. Then, the genotoxicity of 1,4-BQ in lineage-committed progenitors was evaluated using colony forming cell assay following 7–14 days of culture. 1,4-BQ exposure causes significant decreases (p < 0.05) in glutathione level and superoxide dismutase activity, along with significant increases (p < 0.05) in levels of malondialdehyde and protein carbonyls. 1,4-BQ exposure induces DNA damage in BMCs by significantly (p < 0.05) increased percentages of DNA in tail at 7 and 12 μM and tail moment at 12 μM. We found crucial differences in genotoxic susceptibility based on percentages of DNA in tail between lineage-committed progenitors. Myeloid and pre-B lymphoid progenitors appeared to acquire significant DNA damage as compared with the control starting from a low concentration of 1,4-BQ exposure (2.5 µM). In contrast, the erythroid progenitor showed significant damage as compared with the control starting at 5 µM 1,4-BQ. Meanwhile, a significant (p < 0.05) increase in tail moment was only notable at 7 µM and 12 µM 1,4-BQ exposure for all progenitors. Benzene could mediate hematological disorders by promoting bone marrow oxidative stress and lineage-specific genotoxicity targeting HSPCs.
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Affiliation(s)
- Ramya Dewi Mathialagan
- Biomedical Science Programme and Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 53000, Malaysia; (R.D.M.); (Q.M.N.)
| | - Zariyantey Abd Hamid
- Biomedical Science Programme and Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 53000, Malaysia; (R.D.M.); (Q.M.N.)
- Correspondence:
| | - Qing Min Ng
- Biomedical Science Programme and Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 53000, Malaysia; (R.D.M.); (Q.M.N.)
| | - Nor Fadilah Rajab
- Biomedical Science Programme and Center for Healthy Ageing & Wellness, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 53000, Malaysia;
| | - Salwati Shuib
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latif, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia;
| | - Siti Razila Binti Abdul Razak
- Oncological and Radiological Sciences Cluster, Advanced Medical & Dental Institute, Universiti Sains Malaysia, Kepala Batas Bertam, Pulau Pinang 13200, Malaysia;
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Sun S, Zhang C, Gao J, Qin Q, Zhang Y, Zhu H, Yang X, Yang D, Yan H. Benzoquinone induces ROS-dependent mitochondria-mediated apoptosis in HL-60 cells. Toxicol Ind Health 2018; 34:270-281. [PMID: 29506454 DOI: 10.1177/0748233717750983] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Benzene exposure affects the hematopoietic system and leads to the occurrence of various types of leukemia and hematotoxicity. It has been confirmed that active metabolites of benzene, including 1,4-benzoquinone (1,4-BQ), can induce reactive oxygen species (ROS) and apoptosis in the bone marrow, and recent studies have also suggested that benzene exposure can affect mitochondrial function in both experimental animals and cell lines. However, the potential relationship among ROS production, mitochondrial damages, and subsequent apoptosis following benzene exposure has not been well studied in detail. In the present study, we utilized HL-60 cells, a well-characterized human myeloid cell line, as an in vitro model and examined the effects of 1,4-BQ on intracellular ROS formation, mitochondria damage, and the occurrence of apoptotic events with or without using the ROS scavenger N-acetyl-l-cysteine (NAC). The results demonstrated that 1,4-BQ could dose-dependently induce production of ROS and mitochondrial damage as characterized by mitochondrial membrane potential disruption, mitochondrial ultrastructure alteration, and induced apoptosis and activated caspase-3 and caspase-9. Preincubation of HL-60 cells with NAC prior to 1,4-BQ treatment could block 1,4-BQ-induced production of ROS and the occurrence of apoptosis. These results demonstrated that 1,4-BQ induced apoptosis in HL-60 cells through a ROS-dependent mitochondrial-mediated pathway.
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Affiliation(s)
- Shuqiang Sun
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Chunxiao Zhang
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Jiahao Gao
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Qiongyu Qin
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Yaya Zhang
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Hua Zhu
- 2 School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Xinjun Yang
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Dongren Yang
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Hongtao Yan
- 1 Department of Preventive Medicine, School of Public Health and Management, Wenzhou Medical University, Wenzhou, People's Republic of China
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Chow PW, Rajab NF, Chua KH, Chan KM, Abd Hamid Z. Differential responses of lineages-committed hematopoietic progenitors and altered expression of self-renewal and differentiation-related genes in 1,4-benzoquinone (1,4-BQ) exposure. Toxicol In Vitro 2018; 46:122-128. [DOI: 10.1016/j.tiv.2017.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 04/12/2017] [Accepted: 10/02/2017] [Indexed: 01/10/2023]
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Proteome Changes of Human Bone Marrow Mesenchymal Stem Cells Induced by 1,4-Benzoquinone. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2789245. [PMID: 28119923 PMCID: PMC5227119 DOI: 10.1155/2016/2789245] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/11/2016] [Accepted: 11/23/2016] [Indexed: 01/29/2023]
Abstract
Benzene is metabolized to hydroquinone in liver and subsequently transported to bone marrow for further oxidization to 1,4-benzoquinone (1,4-BQ), which may be related to the leukemia and other blood disorders. In the present study, we investigated the proteome profiles of human primary bone marrow mesenchymal stem cells (hBM-MSCs) treated by 1,4-BQ. We identified 32 proteins that were differentially expressed. Two of them, HSP27 and Vimentin, were verified at both mRNA and protein levels and their cellular localization was examined by immunofluorescence. We also found increased mRNA level of RAP1GDS1, a critical factor of metabolism that has been identified as a fusion partner in various hematopoietic malignancies. Therefore, these differentially expressed proteins can play important roles in benzene-mediated hematoxicity.
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Philbrook NA, Winn LM. Investigating the effects of in utero benzene exposure on epigenetic modifications in maternal and fetal CD-1 mice. Toxicol Appl Pharmacol 2015; 289:12-9. [PMID: 26341289 DOI: 10.1016/j.taap.2015.08.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 12/17/2022]
Abstract
Exposure to the ubiquitous environmental pollutant benzene is positively correlated with leukemia in adults and may be associated with childhood leukemia following in utero exposure. While numerous studies implicate oxidative stress and DNA damage as playing a role in benzene-mediated carcinogenicity, emerging evidence suggests that alterations in epigenetic regulations may be involved. The present study aimed to determine whether DNA methylation and/or various histone modifications were altered following in utero benzene exposure in CD-1 mice. Global DNA methylation and promoter-specific methylation of the tumor suppressor gene, p15, were assessed. Additionally, levels of acetylated histones H3, H4, and H3K56, as well as methylated histones H3K9 and H3K27 were assessed by Western blotting. A significant decrease in global DNA methylation of maternal bone marrow was observed following benzene exposure; however no effect on global DNA methylation was detected in fetal livers. Additionally, no effect of benzene exposure was observed on p15 promoter methylation or any measured histone modifications in both maternal bone marrow and fetal livers. These results suggest that the methodology used in the present study did not reveal alterations in DNA methylation and histone modifications following in utero exposure to benzene; however further experimentation investigating these modifications at the whole genome/epigenome level, as well as at later stages of benzene-induced carcinogenesis, are warranted.
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Affiliation(s)
- Nicola A Philbrook
- Department of Biomedical and Molecular Sciences, Graduate Program in Pharmacology and Toxicology, Queen's University, Kingston, ON K7L3N6, Canada
| | - Louise M Winn
- Department of Biomedical and Molecular Sciences, Graduate Program in Pharmacology and Toxicology, Queen's University, Kingston, ON K7L3N6, Canada; School of Environmental Studies, Queen's University, Kingston, ON K7L3N6, Canada.
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Yang J, Bai WL, Chen YJ, Gao A. 1,4-benzoquinone-induced STAT-3 hypomethylation in AHH-1 cells: Role of oxidative stress. Toxicol Rep 2015; 2:864-869. [PMID: 28962422 PMCID: PMC5598509 DOI: 10.1016/j.toxrep.2015.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 05/13/2015] [Accepted: 05/29/2015] [Indexed: 11/19/2022] Open
Abstract
Benzene, a known occupational and environmental contaminant, is associated with increased risk of leukemia. The objectives of this study were to elucidate the regulatory mechanism of the hypomethylated STAT3 involved in benzene toxicity in vitro. As 1,4-benzoquinone (1,4-BQ) is one of benzene’s major toxic metabolites, AHH-1 cells were treated by 1,4-BQ for 24 h with or without pretreatment of the antioxidant a-LA or the methyltransferase inhibitor, 5-aza-2′ deoxycytidine (5-aza). The cell viability was investigated using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. ROS was determined via 2′,7′-dichlorodihydrofluorescein diacetate (DCFDA) flow cytometric assays. The level of oxidative stress marker 8-OHdG was measured by enzyme-linked immunosorbent assay. Methylation-specific PCR was used to detect the methylation status of STAT3. Results indicated the significantly increasing expression of ROS and 8-OHdG which accompanied with STAT3 hypomethylation in 1,4-BQ-treated AHH-1 cells. α-LA suppressed the expression of both ROS and 8-OHdG, simultaneously reversed 1,4-BQ-induced STAT3 hypomethylation. However, although the methylation inhibitor, 5-aza reduced the expression level of ROS and 8-OHdG, but had no obvious inhibiting effect on STAT3 methylation level. Taken together, oxidative stress are involved 1,4-BQ-induced STAT3 methylation expression.
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Key Words
- 1,4-BQ, 1,4-benzoquinone
- 1,4-benzoquinone
- 5-aza, 5-aza-2′ deoxycytidine
- 8-OHdG, 8-hydroxy deoxyguanosine adduct
- DCFH-DA, 2,7-dichlorofluorescein diacetate
- DMSO, dimethylsulfoxide
- DNMT, DNA methyltransferase
- ELISA, enzyme-linked immunosorbent assay
- MSP, methylation-specific PCR
- Methylation
- Oxidative stress
- PBS, phosphate buffered saline
- ROS, reactive oxygen species
- STAT3
- α-LA, alpha lipoic acid
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Affiliation(s)
- Jing Yang
- Department of Occupational Health and Environmental Health, School of Public Health, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Wen-lin Bai
- Department of Occupational Health and Environmental Health, School of Public Health, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Yu-jiao Chen
- Department of Occupational Health and Environmental Health, School of Public Health, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Ai Gao
- Department of Occupational Health and Environmental Health, School of Public Health, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
- Corresponding author at: Department of Occupational Health and Environmental Health, School of Public Health, Capital Medical University, Beijing 100069, China. Tel.: +86 10 83911509.
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Chow PW, Abdul Hamid Z, Chan KM, Inayat-Hussain SH, Rajab NF. Lineage-related cytotoxicity and clonogenic profile of 1,4-benzoquinone-exposed hematopoietic stem and progenitor cells. Toxicol Appl Pharmacol 2015; 284:8-15. [DOI: 10.1016/j.taap.2015.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/25/2014] [Accepted: 01/21/2015] [Indexed: 01/10/2023]
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Ibarra Y, Blair NT. Benzoquinone reveals a cysteine-dependent desensitization mechanism of TRPA1. Mol Pharmacol 2013; 83:1120-32. [PMID: 23478802 DOI: 10.1124/mol.112.084194] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The transient receptor potential ankyrin 1 (TRPA1) nonselective cation channel has a conserved function as a noxious chemical sensor throughout much of Metazoa. Electrophilic chemicals activate both insect and vertebrate TRPA1 via covalent modification of cysteine residues in the amino-terminal region. Although naturally occurring electrophilic plant compounds, such as mustard oil and cinnamaldehyde, are TRPA1 agonists, it is unknown whether arthropod-produced electrophiles activate mammalian TRPA1. We characterized the effects of the electrophilic arthropod defensive compound para-benzoquinone (pBQN) on the human TRPA1 channel. We used whole-cell recordings of human embryonic kidney cells heterologously expressing either wild-type TRPA1 or TRPA1 with three serine-substituted cysteines crucial for electrophile activation (C621S, C641S, C665S). We found that pBQN activates TRPA1 starting at 10 nM and peaking at 300 nM; higher concentrations caused rapid activation followed by a fast decline. Activation by pBQN required reactivity with cysteine residues, but ones that are distinct from those previously reported to be the key targets of electrophiles. The current reduction we found at higher pBQN concentrations was a cysteine-dependent desensitization of TRPA1, and did not require prior activation. The cysteines required for desensitization are not accessible to all electrophiles as iodoacetamide and internally applied 2-(trimethylammonium)ethyl methanesulfonate failed to cause desensitization (despite large activation). Interestingly, following pBQN desensitization, wild-type TRPA1 had dramatically reduced response to the nonelectrophile agonist carvacrol, whereas the triple cysteine mutant TRPA1 retained its full response. Our results suggest that modification of multiple cysteine residues by electrophilic compounds can generate both activation and desensitization of the TRPA1 channel.
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Affiliation(s)
- Yessenia Ibarra
- Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts, USA
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