[Frontiers in Bioscience 15, 1191-1204, June 1, 2010]

Splicing of the Survival Motor Neuron genes and implications for treatment of SMA

Thomas W. Bebee1,3,4, Jordan T. Gladman2,3,4, Dawn S. Chandler1,2,3

1The Molecular, Cellular, and Developmental Biology (MCDB) Graduate Program, The Ohio State University, 2The Integrated Biomedical Science Graduate Program (IBGP), The Ohio State University, 3The Center for Childhood Cancer, The Research Institute at Nationwide Children's Hospital, and Department of Pediatrics, The Ohio State University, Columbus, Ohio, 4Equal Contribution

TABLE OF CONTENTS

1. Abstract
2. Introduction
2. Introduction
3. Pre-mRNA splicing and SMA disease
4. SMN Splicing regulators
4.1. The C to T nucleotide transition in exon 7
4.2. Exonic splicing regulation
4.3. Intronic splicing regulation
5. SMN splicing therapies
5.1. SMA mouse models for therapy testing
5.2. Therapeutic strategies
5.2.1. Antisense oligonucleotides
5.2.2. Trans-splicing
5.2.3. Drugs
6. Summary and perspectives
7. Acknowledgments
8. References

1. ABSTRACT

Proximal spinal muscular atrophy (SMA) is a neuromuscular disease caused by low levels of the survival motor neuron (SMN) protein. The reduced SMN levels are due to loss of the survival motor neuron-1 (SMN1) gene. Humans carry a nearly identical SMN2 gene that generates a truncated protein, due to a C to T nucleotide alteration in exon 7 that leads to inefficient RNA splicing of exon 7. This exclusion of SMN exon 7 is central to the onset of the SMA disease, however, this offers a unique therapeutic intervention in which corrective splicing of the SMN2 gene would restore SMN function. Exon 7 splicing is regulated by a number of exonic and intronic splicing regulatory sequences and trans-factors that bind them. A better understanding of the way SMN pre-mRNA is spliced has lead to the development of targeted therapies aimed at correcting SMN2 splicing. As therapeutics targeted toward correction of SMN2 splicing continue to be developed available SMA mouse models can be utilized in validating their potential in disease treatment.