title: MEF2D Mediates the Neuroprotective Effect of Methylene Blue Against Glutamate-Induced Oxidative Damage in HT22 Hippocampal Cells.
abstract: Methylene blue (MB) can ameliorate behavioral, neurochemical, and neuropathological impairments in animal models of acute and chronic neurodegenerative disorders, but the underlying mechanism remains unclear. Myocyte enhancer factor 2 (MEF2D) is known to promote neuronal survival in several models, and several survival and death signals converge on MEF2D and regulate its activity. Here, we investigated the role of MEF2D in the neuroprotective effect of MB against glutamate-induced toxicity in HT22 neuronal cells. Our results showed that MB, event at less than 100 nM, improved the viability of HT22 cells exposed to 2 mM glutamate. MB attenuated the mitochondrial impairment and quenches the reactive oxygen species (ROS) induced by glutamate. Surprisingly, MB at 50-200 nM did not affect the Nrf2/HO-1 pathway, an important endogenous anti-oxidative system. Further study showed that MB increased the transcription and translation of MEF2D. In addition, MB upregulated the expression of mitochondrial NADH dehydrogenase 6 (ND6) in a MEF2D-dependent manner. Knockdown of MEF2D abolished both MB-medicated increase of ND6 and MB-induced neuroprotection against glutamate-induced toxicity. Moreover, we showed that MB promoted Akt function activity, suppressed GSK-3β activity, and increased MEF2D level in hippocampus of mice and HT22 cells. These findings for the first time demonstrate that MB protects HT22 neuronal cells against glutamate-induced cell death partially via the regulation of MEF2D-associated survival pathway.
authors.affiliation: Department of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510080, China.|International Joint Laboratory (SYSU-PolyU HK) of Novel Anti-Dementia Drugs of Guangdong, Guangzhou, 510006, China.|National and Local United Engineering Lab of Druggability and New Drugs Evaluation, Sun Yat-sen University, Guangzhou, 510080, China.|Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.|Zhejiang Pharmaceutical College, Hangzhou, Zhejiang Province, China.
authors.forename: Zi-Wei
authors.initials: ZW
authors.lastname: Chen
authors.affiliation: Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
authors.forename: Anmin
authors.initials: A
authors.lastname: Liu
authors.affiliation: Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510080, China.|International Joint Laboratory (SYSU-PolyU HK) of Novel Anti-Dementia Drugs of Guangdong, Guangzhou, 510006, China.|National and Local United Engineering Lab of Druggability and New Drugs Evaluation, Sun Yat-sen University, Guangzhou, 510080, China.
authors.forename: Jingkao
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, School of Medicine, Emory University, Atlanta, GA, 30322, USA.
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Li
authors.affiliation: Department of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510080, China.|International Joint Laboratory (SYSU-PolyU HK) of Novel Anti-Dementia Drugs of Guangdong, Guangzhou, 510006, China.|National and Local United Engineering Lab of Druggability and New Drugs Evaluation, Sun Yat-sen University, Guangzhou, 510080, China.
authors.forename: Xiao-Juan
authors.initials: XJ
authors.lastname: Chao
authors.affiliation: Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Department of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510080, China.|International Joint Laboratory (SYSU-PolyU HK) of Novel Anti-Dementia Drugs of Guangdong, Guangzhou, 510006, China.|National and Local United Engineering Lab of Druggability and New Drugs Evaluation, Sun Yat-sen University, Guangzhou, 510080, China.
authors.forename: Pei-Qing
authors.initials: PQ
authors.lastname: Liu
authors.affiliation: Department of Pharmacology, School of Medicine, Emory University, Atlanta, GA, 30322, USA.
authors.forename: Zi-Xu
authors.initials: ZX
authors.lastname: Mao
authors.affiliation: Department of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510080, China. pirb@mail.sysu.edu.cn.|International Joint Laboratory (SYSU-PolyU HK) of Novel Anti-Dementia Drugs of Guangdong, Guangzhou, 510006, China. pirb@mail.sysu.edu.cn.|National and Local United Engineering Lab of Druggability and New Drugs Evaluation, Sun Yat-sen University, Guangzhou, 510080, China. pirb@mail.sysu.edu.cn.|Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China. pirb@mail.sysu.edu.cn.
authors.forename: Rong-Biao
authors.initials: RB
authors.lastname: Pi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D064326:MEF2 Transcription Factors / Q000378:metabolism; D008751:Methylene Blue / Q000494:pharmacology*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D064326:MEF2 Transcription Factors; C578044:Mef2d protein, mouse; D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D018698:Glutamic Acid; D008751:Methylene Blue
keywords: HT22 cells; Methylene blue; Myocyte enhancer factor 2; Neuroprotection; Nuclear factor erythroid 2-related factor 2; Reactive oxygen species