Gautron S, Dos Santos G, Pinto-Henrique D, Koulakoff A, Gros F, Berwald-Netter Y
Laboratoire de Biochimie Cellulaire, Collège de France, Paris, France.
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):7272-6. doi: 10.1073/pnas.89.15.7272.
Previous electrophysiological and pharmacological studies on central and peripheral glia revealed the presence of voltage-gated Na channels with properties that are similar but not identical to those of neuronal Na channels. Here we report the isolation and characterization of a cDNA encoding the C-terminal portion of a putative glial Na-channel (Na-G) alpha subunit. The amino acid sequence deduced from this cDNA indicates that the Na-G represents a separate molecular class within the mammalian Na-channel multigene family. By Northern blot, RNase protection, and in situ hybridization assays, we demonstrate that, in addition to brain astroglia, the Na-G mRNA is expressed in cultures of Schwann cells derived from dorsal root ganglia or from sciatic nerve. In vivo, the Na-G mRNA is detected not only in brain, dorsal root ganglia, and sciatic nerve, but also in tissues outside the nervous system including cardiac and skeletal muscle and lung. Its level varies according to the tissue and is developmentally regulated. The sequence and expression data concur in designating Na-G as an distinct type of Na channel, presumably with low sensitivity to tetrodotoxin.
先前针对中枢和外周神经胶质细胞的电生理及药理学研究表明，存在电压门控钠通道，其特性与神经元钠通道相似但并不完全相同。在此，我们报告了一种编码假定神经胶质钠通道（Na-G）α亚基C末端部分的cDNA的分离及特性鉴定。从该cDNA推导的氨基酸序列表明，Na-G代表哺乳动物钠通道多基因家族中的一个独立分子类别。通过Northern印迹、核糖核酸酶保护及原位杂交分析，我们证明，除脑星形胶质细胞外，Na-G mRNA在源自背根神经节或坐骨神经的施万细胞培养物中也有表达。在体内，不仅在脑、背根神经节和坐骨神经中检测到Na-G mRNA，在包括心脏、骨骼肌和肺在内的神经系统外组织中也能检测到。其水平因组织而异且受发育调控。序列和表达数据一致表明Na-G是一种独特类型的钠通道，推测其对河豚毒素敏感性较低。
