Authors: YuJie Lai Lu Liu XiaoTong Hu Ling He GuoJun Chen
Publish Date: 2017/02/01
Volume: 61, Issue: 3, Pages: 436-448
Abstract
Estrogen exerts multiple actions in the brain and is an important neuroprotective factor in a number of neuronal disorders However the underlying mechanism remains unknown Studies demonstrate that ubiquitinconjugating enzyme 9 ubc9 has an integral role in synaptic plasticity and may contribute to the pathology of neuronal disorders We aimed to investigate the effects of estrogen on ubc9 and in the Alzheimer’s disease brain Ubc9 protein and mRNA were significantly increased in the cortex and hippocampus of APP/PS1 mice with enhanced SUMOylation Systemic estrogen administration led to reduced ubc9 expression in ovariectomized APP/PS1 mice and reduced SUMOylation The inhibition of ubc9 expression by estrogen was found to be dosedependent in cultured neurons However estrogen receptor ER antagonist ICI182780 did not block the inhibition of ubc9 expression by estrogen Furthermore the reduced expression of ubc9 was not mediated by ERα or ERβ agonists alone or in combination but by the membraneimpermeable ER agonist E2bovine serum albumin The activation of the G proteincoupled ER mediated the inhibition of ubc9 expression of estrogen A phosphoinositide 3kinase PI3K inhibitor rather than an extracellular signalregulated kinase inhibitor blocked the inhibition of ubc9 by estrogen Estrogen treatment significantly increased the phosphorylation of PI3K which suggests that activation of the PI3K pathway by estrogen is required for ubc9 regulation Further ubc9 interacted with the synaptic proteins postsynaptic density protein 95 PSD95 and synaptophysin Estrogen decreased the interaction of ubc9 with postsynaptic PSD95 but increased the interaction of ubc9 with presynaptic synaptophysin These results suggest that a membranebound ER might mediate the estrogen inhibition of ubc9 in cortical neurons where PI3K plays an important role We also show that ubc9 can interact with synaptic proteins which are subject to estrogen regulationSupplementary figure legend Estrogen decreases ubc9 expression in cultured cortical neurons Primary cultured cortical neurons were treated with vehicle DMSO 17βestradiol the nonselective estrogen antagonist ICI or 17βestradiol and ICI A Estrogen dosedependently decreased ubc9 expression in cortical neurons Neurons were incubated with vehicle DMSO or various 17βestradiol E2 concentrations 1 nM 10 nM 100 nM or 1 μM for 24 h and ubc9 protein was then measured which were performed in triplicate B Estrogen timedependently decreased ubc9 expression in cortical neurons Timecourse response showed that ubc9 protein levels were decreased within 24 h and remained to be up to 72 h in the presence of E2 10 nM Fig Bwhich were performed in triplicate C ICI182780 failed to block the effects of estrogen on ubc9 expression We preincubated the neurons with the nonselective ER antagonist ICI182780 at a range of concentrations 1 μM 10 μM and 100 μM which were performed in triplicate GIF 109 kb
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