Hippocampal channelopathies in Fragile X Syndrome

 描述（由申请人提供）：我们建议调查两个最近确定的树突状通道病在海马锥体神经元的fmr 1-/y小鼠模型的脆性X综合征（FXS）的生理后果。尽管它们在神经元功能的调节中至关重要，但FXS中离子通道功能的生理学研究却令人惊讶地很少。这是特别值得注意的，因为FMRP，在FXS中缺失的蛋白质，结合超过20种编码许多离子通道蛋白质的mRNA，包括推定的A型K+通道亚基KV4.2和h通道亚基HCN 2，并通过蛋白质-蛋白质相互作用调节离子通道功能。A型K+通道和H-通道对海马树突的整合特性有很强的影响，部分原因是它们非常高的树突表达和特定的生物物理特性。我们建议使用全细胞和细胞贴附电生理记录结合单细胞钙成像，以探讨如何在Ih和IKA的变化改变的fmr 1-/y小鼠的CA 1锥体神经元的远端树突的整合特性。我们还将使用电生理学结合免疫组织化学和蛋白质印迹法来研究这两种通道病变是否持续跨越海马的背腹轴。最后，我们将研究成年小鼠FMRP表达的区域恢复是否可以挽救FXS中发生的细胞和行为异常。这个项目将提供第一个生理调查的影响，channelopathies树突状功能的脆性X综合征。

 DESCRIPTION (provided by applicant): We propose to investigate the physiological consequences of two recently identified dendritic channelopathies in hippocampal pyramidal neurons from the fmr1-/y mouse model of Fragile X syndrome (FXS). Despite their critical importance in the regulation of neuronal function, there have been surprisingly few physiological investigations of ion channel function in FXS. This is particularly noteworthy, because FMRP, the protein that is missing in FXS, binds to more than twenty mRNAs encoding a number of ion channel proteins, including the putative A-type K+ channel subunit KV4.2 and the h-channel subunit HCN2, and modulates ion channel function via protein-protein interactions. A-type K+ channels and h-channels have a strong influence over the integrative properties of hippocampal dendrites in part because of their very high dendritic expression and specific biophysical properties. We propose to use whole-cell and cell-attached electrophysiological recording in combination with single cell calcium imaging to investigate how changes in Ih and IKA alter the integrative properties of the distal dendrites of CA1 pyramidal neurons in the fmr1-/y mouse. We will also use electrophysiology in combination with immunohistochemistry and western blotting to investigate whether these two channelopathies persist across the dorsal-ventral axis of the hippocampus. Lastly, we will investigate whether regional restoration of FMRP expression in adult mice can rescue the cellular and behavioral abnormalities that occur in FXS. This project will provide the first physiological investigation of the impact of channelopathies on dendritic function in Fragile X syndrome.