Department of Neurosurgery, The Affiliated Municipal Hospital, Medical College, Qingdao University, Qingdao, China.
Mol Cell Biochem. 2012 Jun;365(1-2):139-48. doi: 10.1007/s11010-012-1253-7. Epub 2012 Feb 14.
The α-subunit of tetrodotoxin-resistant (TTX-R) voltage-gated sodium channel (VSGC, Nav1.5/SCN5A) has been found from the rat heart and human neuroblastoma cell line NB-1, but its expression in rat brain has not been identified radically. In this study, a reverse transcriptase-polymerase chain reaction was used to clone the full sequence of Nav1.5 (designated as rN1) α-subunit in rat brain and compared the distribution in different lobe of brain in different developmental stages. The open reading frame of rN1 encodes 2,016 amino acid residues and sequence analysis indicated that rN1 is highly homologous with 96.53% amino acids identity to rat cardiac Nav1.5 (rH1) and 96.13% amino acids identity to human neuroblastoma Nav1.5 (hNbR1). It has all the structural features of a VSGC and the presence of a cysteine residue (C373) in the pore loop region of domain I suggests that this channel is resistant to TTX. A new exon (exon6A) that is distinct from rH1 was found in DI-S3-S4, meanwhile an isomer of alternative splicing that deleted 53 amino acids (exon18) was found for the first time in domain DII-III in rN1. (designated as rN1-2). Distribution results demonstrated that rN1 expressed discrepancy in different ages and lobe in brain. The expression level of rN1 was gradually more stable in adult than in neonatal; these results suggest that rN1 has a newly identified exon for alternative splicing that is differentfrom rat heart and is more widely expressed in rat brain than previously thought.
河豚毒素抗性（TTX-R）电压门控钠离子通道（VSGC，Nav1.5/SCN5A）的α亚基已从大鼠心脏和人神经母细胞瘤细胞系 NB-1 中发现，但尚未从大鼠脑中彻底鉴定其表达。在这项研究中，使用逆转录-聚合酶链反应克隆大鼠脑中 Nav1.5 的全长序列（命名为 rN1），并比较不同发育阶段不同脑叶中的分布。rN1 的开放阅读框编码 2016 个氨基酸残基，序列分析表明 rN1 与大鼠心脏 Nav1.5（rH1）具有 96.53%的氨基酸同一性，与人类神经母细胞瘤 Nav1.5（hNbR1）具有 96.13%的氨基酸同一性。它具有 VSGC 的所有结构特征，并且域 I 中的孔环区域中存在半胱氨酸残基（C373）表明该通道对 TTX 具有抗性。在 DI-S3-S4 中发现了一个与 rH1 不同的新外显子（exon6A），同时在 rN1 的 DII-III 域中发现了第一个缺失 53 个氨基酸的选择性剪接异构体（exon18）（命名为 rN1-2）。分布结果表明 rN1 在不同年龄和脑叶中表达存在差异。与新生儿相比，成年大鼠中 rN1 的表达水平逐渐更加稳定；这些结果表明 rN1 具有一个新的选择性剪接外显子，与大鼠心脏不同，并且在大鼠脑中的表达比以前认为的更为广泛。
