大鼠rEag1與rEag2鉀離子通道在次細胞層次的分布

Subcellular localization of rat Eag potassium channels in neurons

張綺真(Chi-Chen Chang)

指導教授 ： 湯志永

國立臺灣大學/醫學院/生理學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.02430

摘要

無資料

關鍵字

星狀細胞 ； 次細胞層次分布 ； rEag鉀離子通道

並列摘要

Subcellular localization of rat Eag potassium channels in neurons
A wide variety of different types of voltage-gated potassium channels are expressed over the entire nervous system, all of which are thought to be involved in many important physiological functions such as the determination of membrane potentials and the firing pattern of action potentials. The ether-á-go-go（Eag）potassium channel is a member of the superfamily of voltage-gated potassium channels. There are two isoforms of Eag potassium channels in rat, rEag1 and rEag2. Currently, the actual physiological role of rEag potassium channels is still unknown. Hence, we decide to address this issue by studying the subcellular localization of rEag potassium channels.
Based on a segment of unique amino acid sequence in the C-terminus of rEag1, we generated a polyclonal anti-rEag1 antibody. The specificity of our anti-rEag1 antibody, as well as that of a commercially available anti-rEag2 antibody, was first verified in stably-transfected rEag1-HEK293 and rEag2-HEK293 cell lines we created.
By studying frozen sections of rat brains we found that the cellular distribution of rEag1 and rEag2 potassium channels determined by immunohistochemistry was mostly consistent with that from previous in situ hybridization experiments.
To further examine the subcellular localization of rEag1 and rEag2 potassium channels, we applied confocal microscopy to study the immunostaining pattern of rEag channels in cultured hippocampal neurons. Anti-MAP2, anti-Tau, anti-densin-180 and anti-synaptophysin antibodies were used as the marker for dendrites, axons, postsynaptic densities and presynaptic terminals, respectively. Our results indicate that in hippocampal neurons, both rEag1 and rEag2 potassium channels are expressed at somatodendritic compartment. Furthermore, rEag1 potassium channels were also found to colocalize with synaptophysin and densin-180, suggesting a synaptic role of rEag1 channels. In addition, by using anti-GFAP antibodies as a marker, we provided the first evidence showing that rEag2 potassium channels are expressed over cell bodies and processes of astrocytes, but rEag1 potassium channels are prominently expressed in cell bodies of astrocytes.
Taken together, our data suggest that rEag1 and rEag2 potassium channels are mainly expressed in the somatodendritic region of neurons and may therefore play an important role in the electrical coupling between dendrites and somas and in the control of the excitability of somas. Furthermore, we propose that rEag1 and rEag2 potassium channels are involved in the maintenance of potassium homeostasis by astrocytes.

並列關鍵字

astrocyte ； subcellular localization ； rat Eag potassium channel

參考文獻

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