The promoters of the survival motor neuron gene (SMN) and its copy (SMNc) share common regulatory elements

Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of motor neurons of the spinal cord . The survival motor neuron gene (SMN) has been recognized as the disease-c ausing gene. SMN is duplicated, and the almost identical copy gene (SMNc) r emains functional in patients with SMA. The expression level of SMNc is tig htly correlated with the clinical severity of the disease. Here, we define the transcription initiation site, delineate the region containing promoter activity, and analyze the sequence of the promoter region of both SMN and SMNc. We show that the promoter sequence and activity of the two genes are quasi identical, providing strong evidence for similar transcription regula tion of the two genes. Therefore, the difference in the level of protein en coded by SMN and SMNc is the result of either different regulatory region(s ) further apart or different posttranscriptional regulation. Interestingly, sequence analysis of the promoter region revealed several consensus bindin g sites for transcription factors. Therefore, the identification of transcr iption factors involved in the regulation of SMNc gene expression may lead to attractive strategies for therapy in SMA.