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Journal of Korean Neurosurgical Society 2007;42(3): 205-210. |
Distinct Regional and Cellular Localization of Hyperpolarization-activated Cyclic Nucleotide-gated Channel 1 in Cerebellar Cortex of Rat. |
Young Joon Kwon, Tae Sung Kim |
1Department of Neurosurgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea. neuriac@gmail.com 2Department of Neurosurgery, School of Medicine, Kyung-Hee University, Seoul, Korea. |
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ABSTRACT |
OBJECTIVE Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels mediate the hyperpolarizationactivated currents (Ih) that participate in regulating neuronal membrane potential and contribute critically to pacemaker activity, promoting synchronization of neuronal networks. However, distinct regional and cellular localization of HCN channels in the brain have not been precisely defined. Aim of this study was to verify the precise cellular location of HCN1 channels in rat cerebellum to better understand the physiological role these channels play in synaptic transmission between CNS neurons. METHODS HCN1 expression in rat brain was analyzed using immunohistochemistry and electron-microscopic observations.
Postsynaptic density-95 (PSD-95), otherwise known as locating and clustering protein, was also examined to clarify its role in the subcellular location of HCN1 channels. In addition, to presume the binding of HCN1 channels with PSD-95, putative binding motifs in these channels were investigated using softwaresearching method. RESULTS HCN1 channels were locally distributed at the presynaptic terminal of basket cell and exactly corresponded with the location of PSD-95. Moreover, nine putative SH3 domain of PSD-95 binding motifs were discovered in HCN1 channels from motif analysis. CONCLUSION Distinct localization of HCN1 channels in rat cerebellum is possible, especially when analyzed in conjunction with the SH3 domain of PSD-95. Considering that HCN1 channels contribute to spontaneous rhythmic action potentials, it is suggested that HCN1 channels located at the presynaptic terminal of neurons may play an important role in synaptic plasticity. |
Key Words:
HCN1 channel; PSD-95; SH3 domain |
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