Human multidrug resistance protein 8 (MRP8/ABCC11), an apical efflux pump for steroid sulfates, is an axonal protein of the CNS and peripheral nervous system
Human multidrug resistance protein 8 (MRP8/ABCC11), an apical efflux pump for steroid sulfates, is an axonal protein of the CNS and peripheral nervous system
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DOI：
10.1016/j.neuroscience.2005.10.025
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发表时间：
2006-01-01
期刊：
影响因子：
3.3
通讯作者：
Keppler, D
中科院分区：
文献类型：
--
作者：
Bortfeld, M;Rius, M;Keppler, D
脱氢表雄酮3-硫酸酯和其他神经甾体在CNS和外周神经系统中合成，它们可以通过与配体门控离子通道相互作用来调节神经元兴奋性。对于这种调节活性，神经类固醇必须从神经元或神经胶质细胞局部释放。在这里，我们确定了完整的膜蛋白ABCC 11（多药耐药蛋白8）作为一个ATP依赖性的外排泵类固醇硫酸盐，包括脱氢表雄酮3-硫酸盐，并将其定位于人类中枢神经系统和外周神经系统的轴突。用实时荧光定量PCR方法检测人脑中ABCC 11 mRNA的表达。针对ABCC 11产生的抗体用于通过免疫印迹和免疫荧光显微镜检测脑中的蛋白质。ABCC 11优先发现于脑的白色物质中，并与神经丝共定位，表明其为轴突蛋白。此外，ABCC 11定位于周围神经系统的轴突。对于功能性研究，ABCC 11在极化的Madin-Darby犬肾细胞中表达，在那里它被分选到顶膜。这种顶端分选与ABCC 11在神经元轴突膜上的定位一致。含有重组ABCC 11的由内而外的质膜囊泡介导的ATP依赖的脱氢表雄酮3-硫酸酯转运，Km值为21 μ M。这种转运功能与ABCC 11蛋白在GABAA受体附近的定位一起与ABCC 11在脱氢表雄酮3-硫酸酯从神经元释放到脱氢表雄酮3-硫酸酯介导的受体调节位点中的作用一致。我们的研究结果可能为人类ABCC 11基因突变的特征及其与神经系统疾病的联系提供了基础。(c)2005由Elsevier Ltd代表IBRO出版。
Dehydroepiandrosterone 3-sulfate and other neurosteroids are synthesized in the CNS and peripheral nervous system where they may modulate neuronal excitability by interacting with ligand-gated ion channels. For this modulatory activity, neurosteroids have to be locally released from either neurons or glial cells. We here identify the integral membrane protein ABCC11 (multidrug resistance protein 8) as an ATP-dependent efflux pump for steroid sulfates, including dehydroepiandrosterone 3-sulfate, and localize it to axons of the human CNS and peripheral nervous system. ABCC11 mRNA was detected in human brain by real-time polymerase chain reaction. Antibodies raised against ABCC11 served to detect the protein in brain by immunoblotting and immunofluorescence microscopy. ABCC11 was preferentially found in the white matter of the brain and co-localized with neurofilaments indicating that it is an axonal protein. Additionally, ABCC11 was localized to axons of the peripheral nervous system. For functional studies, ABCC11 was expressed in polarized Madin-Darby canine kidney cells where it was sorted to the apical membrane. This apical sorting is in accordance with the localization of ABCC11 to the axonal membrane of neurons. Inside-out plasma membrane vesicles containing recombinant ABCC11 mediated ATP-dependent transport of dehydroepiandrosterone 3-sulfate with a K-m value of 21 mu M. This transport function together with the localization of the ABCC11 protein in vicinity to GABAA receptors is consistent with a role of ABCC11 in dehydroepiandrosterone 3-sulfate release from neurons to sites of dehydroepiandrosterone 3-sulfate-mediated receptor modulation. Our findings may provide a basis for the characterization of mutations in the human ABCC11 gene and their linkage with neurological disorders. (c) 2005 Published by Elsevier Ltd on behalf of IBRO.