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Liu N, Zhang XL, Jiang SY, Shi JH, Cui JH, Liu XL, Han LH, Gong KR, Yan SC, Xie W, Zhang CY, Shao G. Neuroprotective mechanisms of DNA methyltransferase in a mouse hippocampal neuronal cell line after hypoxic preconditioning. Neural Regen Res 2020; 15:2362-2368. [PMID: 32594061 PMCID: PMC7749487 DOI: 10.4103/1673-5374.285003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Hypoxic preconditioning has been shown to improve hypoxic tolerance in mice, accompanied by the downregulation of DNA methyltransferases (DNMTs) in the brain. However, the roles played by DNMTs in the multiple neuroprotective mechanisms associated with hypoxic preconditioning remain poorly understood. This study aimed to establish an in vitro model of hypoxic preconditioning, using a cultured mouse hippocampal neuronal cell line (HT22 cells), to examine the effects of DNMTs on the endogenous neuroprotective mechanisms that occur during hypoxic preconditioning. HT22 cells were divided into a control group, which received no exposure to hypoxia, a hypoxia group, which was exposed to hypoxia once, and a hypoxic preconditioning group, which was exposed to four cycles of hypoxia. To test the ability of hypoxic preadaptation to induce hypoxic tolerance, cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium assay. Cell viability improved in the hypoxic preconditioning group compared with that in the hypoxia group. The effects of hypoxic preconditioning on the cell cycle and apoptosis in HT22 cells were examined by western blot assay and flow cytometry. Compared with the hypoxia group, the expression levels of caspase-3 and spectrin, which are markers of early apoptosis and S-phase arrest, respectively, noticeably reduced in the hypoxic preconditioning group. Finally, enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and western blot assay were used to investigate the changes in DNMT expression and activity during hypoxic preconditioning. The results showed that compared with the control group, hypoxic preconditioning downregulated the expression levels of DNMT3A and DNMT3B mRNA and protein in HT22 cells and decreased the activities of total DNMTs and DNMT3B. In conclusion, hypoxic preconditioning may exert anti-hypoxic neuroprotective effects, maintaining HT22 cell viability and inhibiting cell apoptosis. These neuroprotective mechanisms may be associated with the inhibition of DNMT3A and DNMT3B.
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Affiliation(s)
- Na Liu
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Xiao-Lu Zhang
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Shu-Yuan Jiang
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Jing-Hua Shi
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Jun-He Cui
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Xiao-Lei Liu
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Li-Hong Han
- Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Ke-Rui Gong
- Department of Oral and Maxillofacial Surgery, University of California San Francsico, San Francisco, CA, USA
| | - Shao-Chun Yan
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Wei Xie
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Chun-Yang Zhang
- Department of Neurosurgery, the First Affiliated Hospital of Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Guo Shao
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing; Department of Neurosurgery, the First Affiliated Hospital of Baotou Medical College, Baotou, Inner Mongolia Autonomous Region,, China
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Fox C, Walsh P, Mulhall KJ. Molecular Mechanism of Ischaemic Preconditioning of Skeletal Muscle In Vitro. Cureus 2018; 10:e3763. [PMID: 30820383 PMCID: PMC6389019 DOI: 10.7759/cureus.3763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Introduction Ischaemic preconditioning (IPC) is a phenomenon whereby tissues develop an increased tolerance to ischaemia and subsequent reperfusion if first subjected to sublethal periods of ischaemia. Despite extensive investigation of IPC, the molecular mechanism remains largely unknown. Our aim was to show genetic changes that occur in skeletal muscle cells in response to IPC. Methods We established an in vitro model of IPC using a human skeletal muscle cell line. Gene expression of both control and preconditioned cells at various time points was determined. The genes examined were hypoxia-inducible factor-1 alpha (HIF-1 alpha), early growth response 1 (EGR1), JUN, and FOS. HIF-1 alpha is a marker of hypoxia. EGR1, JUN, and FOS are early response genes and may play a role in the protective responses induced by IPC. Results HIF-1 alpha was upregulated following one and two hours of simulated ischaemia (p = 0.076 and 0.841, respectively) verifying that hypoxic conditions were met using our model. Expression of EGR1 and FOS was upregulated and peaked after one hour of hypoxia (p = 0.001 and <0.00, respectively). cFOS was upregulated at two and three hours of hypoxia. IPC prior to simulated hypoxia resulted in a greater level of upregulation of EGR1, JUN and FOS genes (p = <0.00, 0.047, and <0.00 respectively). Conclusion This study has supported the use of our hypoxic model for studying IPC in vitro. IPC results in a greater upregulation of protective genes in skeletal muscle cells exposed to hypoxia than in control cells. We have demonstrated hitherto unknown molecular mechanisms of IPC in cell culture.
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Affiliation(s)
- Ciara Fox
- Orthopaedics, Royal College of Surgeons in Ireland, Dublin, IRL
| | - Pauline Walsh
- Orthopaedics, Orthopaedic Research and Innovation Foundation, Dublin, IRL
| | - Kevin J Mulhall
- Orthopaedics, Orthopaedic Research and Innovation Foundation, Dublin, IRL
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