Enhancement of Sodium Current in NG108-15 Cells during Neural Differentiation is Mainly due to an Increase in NaV1.7 Expression |
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Authors: | Akinori Kawaguchi Hajime Asano Kayoko Matsushima Tetsuyuki Wada Shigeru Yoshida Seiji Ichida |
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Institution: | (1) Department of Biological Chemistry, School of Pharmacy, Kinki University , Kowakae 3-4-1, Higasiosaka 577-8502, Japan;(2) Department of Life Science, School of Science & Engineering, Kinki University, Kowakae 3-4-1, Higashiosaka 577-8502, Japan |
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Abstract: | It is well known that morphological and functional changes during neural differentiation sometimes accompany the expression
of various voltage-gated ion channels. In this work, we investigated whether the enhancement of sodium current in differentiated
neuroblastoma × glioma NG108-15 cells treated with dibutyryl cAMP is related to the expression of voltage-gated sodium channels.
The results were as follows. (1) Sodium current density on peak voltage in differentiated cells was significantly enhanced
compared with that in undifferentiated cells, as detected by the whole-cell patch clamp method. The steady-state inactivation
curve in differentiated cells was similar to that for undifferentiated cells, but a hyperpolarized shift in the activation
curve for differentiated cells was observed. The sodium currents of differentiated and undifferentiated cells were completely
inhibited by 10−7 M tetrodotoxin (TTX). (2) The only NaV mRNA with an increased expression level during neuronal differentiation was that for NaV1.7, as observed by real-time PCR analysis. (3) The increase in the level of NaV1.7 α subunit expression during neuronal differentiation was also observed by immunocytochemistry; in particular, the localization
of NaV1.7 α subunits on the soma, varicosities and growth cone was significant. These results suggest that the enhancement of TTX-sensitive
sodium current density in differentiated NG108-15 cells is mainly due to the increase in the expression of the TTX-sensitive
voltage-gated Na+ channel, NaV1.7. |
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Keywords: | Voltage-gated sodium channel NaV1 7 Neuronal differentiation Bt2cAMP NG108-15 cell Electrophysiology |
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