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Wang XL, Miao C, Su Y, Zhang C, Meng X. MAD2B Blunts Chronic Unpredictable Stress and Corticosterone Stimulation-Induced Depression-Like Behaviors in Mice. Int J Neuropsychopharmacol 2022; 26:137-148. [PMID: 36573299 PMCID: PMC9926055 DOI: 10.1093/ijnp/pyac083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 12/23/2022] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Depression is a prevalent and recurrent psychiatric disorder. Aberrant neural structure and activity play fundamental roles in the occurrence of depression. Mitotic arrest deficient protein (MAD2B) is highly expressed in neurons and may be implicated in synaptic plasticity in the central nervous system. However, the effect of MAD2B in depression, as well as the related molecular mechanism, is uncertain. METHODS Here, we employed mouse models of depression induced by chronic unpredictable stress exposure or corticosterone (CORT) stimulation. Depression-like behaviors in mice were evaluated by sucrose preference, forced swimming, and tail suspension tests. Hippocampal MAD2B overexpression was mediated by adeno-associated virus 8 containing enhanced green fluorescent protein. In vitro primary neuronal cells were obtained from the hippocampus of rat embryos and were treated with CORT, and MAD2B overexpression was performed using lentivirus. MAD2B and glutamate metabotropic receptor 4 (GRM4) levels were evaluated by western blots and quantitative PCR. Primary neuronal miR-29b-3p expression was detected by quantitative PCR. RESULTS MAD2B expression was reduced in the hippocampus in mice exhibiting depressive-like behaviors. However, hippocampal MAD2B overexpression protected mice from developing either chronic unpredictable stress- or CORT-induced depression-like behaviors, an effect associated with reduced expression of GRM4, a presynaptic receptor involved in depression. Moreover, MAD2B overexpression in primary neuronal cells also decreased GRM4 expression while enhancing the level of miR-29b-3p; this phenomenon was also observed under CORT stimulation. CONCLUSIONS Our results suggest an important role of neuronal MAD2B in the pathogenesis of depression via the miR-29b-3p/GRM4 signaling pathway. MAD2B could be a potential therapeutic target for depressive disorders.
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Affiliation(s)
| | | | - Yanfang Su
- Department of Neurobiology, Institute of Brain Research, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chun Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xianfang Meng
- Correspondence: Xianfang Meng, PhD, Department of Neurobiology, Institute of Brain Research, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, 430030, Wuhan, China ()
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Kubis-Kubiak A, Wiatrak B, Piwowar A. Hyper-glycemia and insulinemia induce morphological changes and modulate secretion of S100B, S100A8, amyloid β 1–40 and amyloid β 1–42, in a model of human dopaminergic neurons. Biomed Pharmacother 2022; 156:113869. [DOI: 10.1016/j.biopha.2022.113869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/10/2022] [Accepted: 10/13/2022] [Indexed: 11/02/2022] Open
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Cheng L, Su Y, Zhi K, Xie Y, Zhang C, Meng X. Conditional deletion of MAD2B in forebrain neurons enhances hippocampus-dependent learning and memory in mice. Front Cell Neurosci 2022; 16:956029. [PMID: 36212696 PMCID: PMC9538151 DOI: 10.3389/fncel.2022.956029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Mitotic arrest deficient 2-like protein 2 (MAD2B) is not only a DNA damage repair agent but also a cell cycle regulator that is widely expressed in the hippocampus and the cerebral cortex. However, the functions of MAD2B in hippocampal and cerebral cortical neurons are poorly understood. In this study, we crossed MAD2Bflox/flox and calcium/calmodulin-dependent protein kinase II alpha (Camk2a)-Cre mice to conditionally knock out MAD2B in the forebrain pyramidal neurons by the Cre/loxP recombinase system. First, RNA sequencing suggested that the differentially expressed genes in the hippocampus and the cerebral cortex between the WT and the MAD2B cKO mice were related to learning and memory. Then, the results of behavioral tests, including the Morris water maze test, the novel object recognition test, and the contextual fear conditioning experiment, suggested that the learning and memory abilities of the MAD2B cKO mice had improved. Moreover, conditional knockout of MAD2B increased the number of neurons without affecting the number of glial cells in the hippocampal CA1 and the cerebral cortex. At the same time, the number of doublecortin-positive (DCX+) cells was increased in the dentate gyrus (DG) of the MAD2B cKO mice. In addition, as shown by Golgi staining, the MAD2B cKO mice had more mushroom-like and long-like spines than the WT mice. Transmission electron microscopy (TEM) revealed that spine synapses increased and shaft synapses decreased in the CA1 of the MAD2B cKO mice. Taken together, our findings indicated that MAD2B plays an essential role in regulating learning and memory.
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Affiliation(s)
- Li Cheng
- Department of Neurobiology, Institute of Brain Research, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yanfang Su
- Department of Neurobiology, Institute of Brain Research, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kaining Zhi
- Department of Neurobiology, Institute of Brain Research, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yaru Xie
- Department of Neurobiology, Institute of Brain Research, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chun Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Chun Zhang
| | - Xianfang Meng
- Department of Neurobiology, Institute of Brain Research, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Xianfang Meng
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4
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Functions and Regulation of Meiotic HORMA-Domain Proteins. Genes (Basel) 2022; 13:genes13050777. [PMID: 35627161 PMCID: PMC9141381 DOI: 10.3390/genes13050777] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 11/20/2022] Open
Abstract
During meiosis, homologous chromosomes must recognize, pair, and recombine with one another to ensure the formation of inter-homologue crossover events, which, together with sister chromatid cohesion, promote correct chromosome orientation on the first meiotic spindle. Crossover formation requires the assembly of axial elements, proteinaceous structures that assemble along the length of each chromosome during early meiosis, as well as checkpoint mechanisms that control meiotic progression by monitoring pairing and recombination intermediates. A conserved family of proteins defined by the presence of a HORMA (HOp1, Rev7, MAd2) domain, referred to as HORMADs, associate with axial elements to control key events of meiotic prophase. The highly conserved HORMA domain comprises a flexible safety belt sequence, enabling it to adopt at least two of the following protein conformations: one closed, where the safety belt encircles a small peptide motif present within an interacting protein, causing its topological entrapment, and the other open, where the safety belt is reorganized and no interactor is trapped. Although functional studies in multiple organisms have revealed that HORMADs are crucial regulators of meiosis, the mechanisms by which HORMADs implement key meiotic events remain poorly understood. In this review, we summarize protein complexes formed by HORMADs, discuss their roles during meiosis in different organisms, draw comparisons to better characterize non-meiotic HORMADs (MAD2 and REV7), and highlight possible areas for future research.
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de Krijger I, Boersma V, Jacobs JJL. REV7: Jack of many trades. Trends Cell Biol 2021; 31:686-701. [PMID: 33962851 DOI: 10.1016/j.tcb.2021.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/23/2021] [Accepted: 04/08/2021] [Indexed: 01/01/2023]
Abstract
The HORMA domain protein REV7, also known as MAD2L2, interacts with a variety of proteins and thereby contributes to the establishment of different complexes. With doing so, REV7 impacts a diverse range of cellular processes and gained increasing interest as more of its activities became uncovered. REV7 has important roles in translesion synthesis and mitotic progression, and acts as a central component in the recently discovered shieldin complex that operates in DNA double-strand break repair. Here we discuss the roles of REV7 in its various complexes, focusing on its activity in genome integrity maintenance. Moreover, we will describe current insights on REV7 structural features that allow it to be such a versatile protein.
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Affiliation(s)
- Inge de Krijger
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Vera Boersma
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Jacqueline J L Jacobs
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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Bhat A, Qin Z, Wang G, Chen W, Xiao W. Rev7, the regulatory subunit of Polζ, undergoes UV-induced and Cul4-dependent degradation. FEBS J 2017; 284:1790-1803. [PMID: 28440919 DOI: 10.1111/febs.14088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 03/19/2017] [Accepted: 04/18/2017] [Indexed: 11/26/2022]
Abstract
In eukaryotic cells, Rev7 interacts with Rev3 and functions as a regulatory subunit of Polζ, a translesion DNA synthesis (TLS) polymerase. In addition to its role in TLS, mammalian Rev7, also known as Mad2B/Mad2L2, participates in multiple cellular activities including cell cycle progression and double-strand break repair through its interaction with several proteins. Here we show that in mammalian cells, Rev7 undergoes ubiquitin/proteasome-mediated degradation upon UV irradiation in a time-dependent manner. We identified the Rev7 N-terminal destruction box as the degron and Cul4A/B as putative E3 ligases in this process. We also show that the nucleotide excision repair (NER) pathway protein HR23B physically interacts and colocalizes with Rev7 in the nuclear foci after UV irradiation and protects Rev7 from accelerated degradation. Furthermore, a similar Rev7 degradation profile was observed in cells treated with the UV-mimetic agent 4-nitroquinoline 1-oxide but not with cisplatin or camptothecin, suggesting a role of the NER pathway protein(s) in UV-induced Rev7 degradation. These data and the observation that cells deficient in Rev7 are sensitized to UV irradiation while excessive Rev7 protects cells from UV-induced DNA damage provide a new insight into the potential interplay between TLS and NER.
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Affiliation(s)
- Audesh Bhat
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada.,Centre for Molecular Biology, Central University of Jammu, India
| | - Zhoushuai Qin
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada.,College of Life Sciences, Capital Normal University, Beijing, China
| | - Guifen Wang
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Wangyang Chen
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Wei Xiao
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada.,College of Life Sciences, Capital Normal University, Beijing, China
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Meng X, Chu G, Ye C, Tang H, Qiu P, Hu Y, Li M, Zhang C. Involvement of AMPK in regulating the degradation of MAD2B under high glucose in neuronal cells. J Cell Mol Med 2016; 21:1150-1158. [PMID: 27957796 PMCID: PMC5431170 DOI: 10.1111/jcmm.13046] [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] [Received: 07/13/2016] [Accepted: 10/24/2016] [Indexed: 11/29/2022] Open
Abstract
Although our recent study has demonstrated that mitotic spindle assembly checkpoint protein (MAD2B) mediates high glucose‐induced neuronal apoptosis, the mechanisms for MAD2B degradation under hyperglycaemia have not yet been elucidated. In this study, we first found that the activation of adenosine 5′‐monophosphate (AMP)‐activated protein kinase (AMPK) was decreased in neurons, accompanied with the increased expression of MAD2B. Mechanistically, we demonstrated that activation of AMPK with its activators such as AICAR and metformin decreased the expression of MAD2B, indicating a role of AMPK in regulating the expression of MAD2B. Moreover, activation of AMPK prevented neuronal cells from high glucose‐induced injury as demonstrated by the reduced expression of cyclin B1 and percentage of apoptosis as detected by TUNEL. We further found that when total protein synthesis was suppressed by chlorhexidine, the degradation of MAD2B was slower in high glucose‐treated neurons and was mainly dependent on the ubiquitin–proteasome system. Finally, it was indicated that high glucose inhibited the ubiquitination of MAD2B, which could be reversed by activation of AMPK. Collectively, this study demonstrates that AMPK acts as a key regulator of MAD2B expression, suggesting that activation of AMPK signalling might be crucial for the treatment of high glucose‐induced neuronal injury.
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Affiliation(s)
- Xianfang Meng
- Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Guangpin Chu
- Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chen Ye
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hui Tang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ping Qiu
- Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yue Hu
- Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Man Li
- Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chun Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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8
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Bhat A, Wu Z, Maher VM, McCormick JJ, Xiao W. Rev7/Mad2B plays a critical role in the assembly of a functional mitotic spindle. Cell Cycle 2016; 14:3929-38. [PMID: 26697843 DOI: 10.1080/15384101.2015.1120922] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The spindle assembly checkpoint (SAC) acts as a guardian against cellular threats that may lead to chromosomal missegregation and aneuploidy. Mad2, an anaphase-promoting complex/cyclosome-Cdc20 (APC/C(Cdc20)) inhibitor, has an additional homolog in mammals known as Mad2B, Mad2L2 or Rev7. Apart from its role in Polζ-mediated translesion DNA synthesis and double-strand break repair, Rev7 is also believed to inhibit APC/C by negatively regulating Cdh1. Here we report yet another function of Rev7 in cultured human cells. Rev7, as predicted earlier, is involved in the formation of a functional spindle and maintenance of chromosome segregation. In the absence of Rev7, cells tend to arrest in G2/M-phase and display increased monoastral and abnormal spindles with misaligned chromosomes. Furthermore, Rev7-depleted cells show Mad2 localization at the kinetochores of metaphase cells, an indicator of activated SAC, coupled with increased levels of Cyclin B1, an APC(Cdc20) substrate. Surprisingly unlike Mad2, depletion of Rev7 in several cultured human cell lines did not compromise SAC activity. Our data therefore suggest that besides its role in APC/C(Cdh1) inhibition, Rev7 is also required for mitotic spindle organization and faithful chromosome segregation most probably through its physical interaction with RAN.
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Affiliation(s)
- Audesh Bhat
- a Department of Microbiology and Immunology ; University of Saskatchewan ; Saskatchewan , Canada
| | - Zhaojia Wu
- a Department of Microbiology and Immunology ; University of Saskatchewan ; Saskatchewan , Canada
| | - Veronica M Maher
- b Carcinogenesis Laboratory; Michigan State University ; East Lansing , MI USA
| | - J Justin McCormick
- b Carcinogenesis Laboratory; Michigan State University ; East Lansing , MI USA
| | - Wei Xiao
- a Department of Microbiology and Immunology ; University of Saskatchewan ; Saskatchewan , Canada.,c College of Life Sciences; Capital Normal University ; Beijing , China
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Wang X, Yang Z, Sun Y, Zhou H, Chu G, Zhang J, Meng X. Ethanol Activation of PKA Mediates Single-Minded 2 Expression in Neuronal Cells. Mol Neurobiol 2014; 52:1234-1244. [PMID: 25319570 DOI: 10.1007/s12035-014-8924-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 10/06/2014] [Indexed: 10/24/2022]
Abstract
Prenatal ethanol exposure can cause extensive apoptotic neurodegeneration throughout the developing central nervous system (CNS), which results in cognitive deficits and memory decline. However, the underlying mechanisms need further study. Single-minded 2 (Sim2), a transcriptional repressor, is reportedly involved in diseases that impair learning and memory, such as Down syndrome (DS) and Alzheimer's disease. It is still unknown whether Sim2 is involved in regulating ethanol-mediated neuronal injury that might ultimately lead to neuronal dysfunction and subsequent learning and memory deficits. To study the effects of ethanol on Sim2 expression and neuronal injury, we used animal models and cell culture experiments. Our results indicated that in SH-SY5Y cells, ethanol exposure increased Sim2 expression and levels of cleaved caspase 3, which is a marker for cells undergoing apoptosis. Silencing Sim2 expression attenuated caspase 3 activation and cellular apoptosis. We also found that protein kinase A (PKA) activation induced Sim2 expression, as did ethanol. Inhibiting the PKA signaling pathway with H-89 decreased Sim2 expression and cleavage of caspase 3 that was induced by ethanol in vivo and in vitro. We further found that PKA regulated Sim2 expression at the transcriptional level. These results demonstrate that ethanol leads to increased Sim2 expression via the PKA pathway, ultimately resulting in apoptotic cell death.
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Affiliation(s)
- Xiaolan Wang
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.,The Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhihua Yang
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yinan Sun
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hanjing Zhou
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Guangpin Chu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jing Zhang
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xianfang Meng
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China. .,The Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Meng X, Wang X, Tian X, Yang Z, Li M, Zhang C. Protection of neurons from high glucose-induced injury by deletion of MAD2B. J Cell Mol Med 2014; 18:844-51. [PMID: 24444371 PMCID: PMC4119390 DOI: 10.1111/jcmm.12229] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 12/09/2013] [Indexed: 12/19/2022] Open
Abstract
Diabetic encephalopathy may lead to cognitive deficits in diabetic patients and diminish quality of life. It has been shown that protracted hyperglycaemia is directly associated with neuronal apoptosis, which is involved in diabetic encephalopathy. The anaphase-promoting complex (APC) is essential for the survival of post-mitotic neurons. In our previous study, we found that the mitotic arrest deficient protein MAD2B, one of APC inhibitors, was expressed in neurons in central nervous system. However, whether MAD2B is involved in hyperglycaemia-induced apoptosis and thus takes part in diabetic encephalopathy is still unknown. To address this issue, we first explored the expression of MAD2B and cyclin B1 detected by immunofluorescence and Western blot. It was found that hyperglycaemia remarkably increased the expression of MAD2B and accumulation of cyclin B1 in cortices of diabetes mellitus rat model and in cultured primary neurons. To further explore the role of MAD2B in hyperglycaemia-induced neuronal injury, we depleted MAD2B expression by a specifically targeted shRNA against MAD2B. We observed that MAD2B deficiency alleviated cyclin B1 expression and apoptotic neuronal death. These results demonstrate that MAD2B expression is the main culprit for accumulation of cyclin B1 and apoptosis in neurons under high glucose. Moreover, inhibition of the expression of MAD2B prevented neurons from entering an aberrant S phase that led differentiated neurons into apoptotic cell death. These results suggest that hyperglycaemia induced neuronal apoptosis through inducing expression of MAD2B, which represents a novel mechanism of diabetic encephalopathy.
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Affiliation(s)
- Xianfang Meng
- Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Wang X, Song Y, Chen L, Zhuang G, Zhang J, Li M, Meng XF. Contribution of single-minded 2 to hyperglycaemia-induced neurotoxicity. Neurotoxicology 2013; 35:106-12. [PMID: 23333261 DOI: 10.1016/j.neuro.2013.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 12/05/2012] [Accepted: 01/06/2013] [Indexed: 12/19/2022]
Abstract
Diabetes mellitus is associated to central nervous system damage, which results in impairment of brain functions and cognitive deficits and decline in memory. However, the mechanisms mediating the actions of glucose on the neurons remained elusive. Single-minded 2 (Sim2), a basic helix-loop-helix (bHLH)-PAS transcriptional repressor, is thought to be involved in some symptoms of Down syndrome. We hypothesized that Sim2 mediated hyperglycaemia-induced neuronal injury and impairment of learning and memory. It was found that expression of Sim2 protein in cortical neurons was increased in streptozotocin-induced diabetes mellitus rat model. Drebrin, down-regulated by Sim2, was subsequently decreased as detected by confocal laser scanning microscopy and Western blot analysis. The expression pattern of Sim2 and Drebrin correspond to 50mmol/L glucose (hyperglycaemia) was also found in primary cultured neurons. Curcumin, one neuroprotective agent, inhibited hyperglycaemia-induced neurotoxicity. Moreover, curcumin alleviated Sim2 expression, and reversely raised Drebrin expression in neurons treated with hyperglycaemia. Finally, we found that silencing Sim2 expression decreased hyperglycaemia-induced neuronal injury. In conclusion, Sim2 may mediate neurotoxicity during hyperglycaemia and thereby play a critical role in the development of hyperglycaemia-induced cognitive deficits.
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Affiliation(s)
- Xiaolan Wang
- Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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