Identification of the promoter region and the 5′-untranslated exons of the human voltage-gated sodium channel Nav1.1 gene (SCN1A) and enhancement of gene expression by the 5′-untranslated exons

✍ Scribed by Yue-Sheng Long; Qi-Hua Zhao; Tao Su; Yang-Lin Cai; Yang Zeng; Yi-Wu Shi; Yong-Hong Yi; Hao-Hui Chang; Wei-Ping Liao

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 311 KB
• Volume: 86
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.21790

✦ Synopsis

Abstract

Voltage‐gated sodium channels play critical roles in the excitability of the brain. A decreased level of Na~v~1.1 has been identified as the cause of severe myoclonic epilepsy in infancy. In the present study, we identified the transcription start site and three 5′‐untranslated exons of SCN1A by using 5′‐full RACE. The 2.5‐kb region upstream of the transcription start site was targeted as a potential location of the promoter. The 2.5‐kb genomic fragment (P~2.5~, from +26 to –2,500) and the 2.7‐kb fragment (P~2.7~, P~2.5~ combined with the 227‐bp 5′‐untranslated exons) were cloned to produce luciferase constructs. The P~2.5~ and the P~2.7~ drove luciferase gene expression in the human neuroblastoma cell line SH‐SY5Y but not in the human embryonic kidney cell line HEK‐293. The 5′‐untranslated exons could greatly enhance gene expression in SH‐SY5Y cells. The P~2.7~ could be used as a functional unit to study the role of SCN1A noncoding sequences in gene expression. These findings will also help in exploring the possibility of promoter mutant‐induced diseases and revealing the mechanism underlying the regulation of SCN1A expression in the normal brain. © 2008 Wiley‐Liss, Inc.