Protection of neurons from high glucose-induced injury by deletion of MAD2B.
Bottom Line: 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.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.These results demonstrate that MAD2B expression is the main culprit for accumulation of cyclin B1 and apoptosis in neurons under high glucose.
Affiliation: Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.Show MeSH
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Mentions: We first detected that whether hyperglycaemia induced MAD2B expression in STZ-induced DM rat model. Streptozotocin-treated rats exhibited significant increase in blood glucose level and decrease in body weight as we described previously . Results of immunofluorescence staining and Western blot analyses showed that MAD2B was significantly increased in cortical neurons of DM rats (Fig. 1A–C). Then, we further explored whether high glucose directly increased MAD2B expression of in vitro-cultured cortical neurons. As shown in Figure 1D and E, different concentrations of glucose markedly increased the expression of MAD2B at 24 hrs in neurons. However, the expression of MAD2B was almost unchanged under different concentrations of mannitol (Fig. 1F), which indicated that the increased expression of MAD2B under high glucose did not result from the changes in osmolality. We chose 50 mM glucose to treat neurons in the following study, because this concentration has been used in many research works to mimic hyperglycaemia in vitro [30,31]. It was shown that the expression of MAD2B was increased in a time-dependent manner as detected by real-time RT-PCR (Fig. 1G). MAD2B mRNA expression started to up-regulate after treatment with 50 mM glucose for 12 hrs. Consistent with these data, Western blot (Fig. 1H and I) further showed that MAD2B expression was substantially increased with 50 mM glucose. In the present study, we further detected Cdh1 expression, which is an activator for the anaphase-promoting complex/cyclosome (APC/C). Interestingly, the expression of Cdh1 was almost unchanged as detected by Western blot analyses (Fig. 1J and K).
Affiliation: Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.