Journal Article

Regulation of murine survival motor neuron (<i>Smn</i>) protein levels by modifying <i>Smn</i> exon 7 splicing

Christine J. DiDonato, Christian L. Lorson, Yves De Repentigny, Louise Simard, Chantal Chartrand, Elliot J. Androphy and Rashmi Kothary

in Human Molecular Genetics

Volume 10, issue 23, pages 2727-2736
Published in print November 2001 | ISSN: 0964-6906
Published online November 2001 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/10.23.2727
Regulation of murine survival motor neuron (Smn) protein levels by modifying Smn exon 7 splicing

Show Summary Details

Preview

Proximal spinal muscular atrophy (SMA) is caused by mutations in the survival motor neuron gene (SMN1). In humans, two nearly identical copies of SMN exist and differ only by a single non-polymorphic C→T nucleotide transition in exon 7. SMN1 contains a ‘C’ nucleotide at the +6 position of exon 7 and produces primarily full-length SMN transcripts, whereas SMN2 contains a ‘T’ nucleotide and produces high levels of a transcript that lacks exon 7 and a low level of full-length SMN transcripts. All SMA patients lack a functional SMN1 gene but retain at least one copy of SMN2, suggesting that the low level of full-length protein produced from SMN2 is sufficient for all cell types except motor neurons. The murine Smn gene is not duplicated or alternatively spliced. It resembles SMN1 in that the critical exon 7 +6 ‘C’ nucleotide is conserved. We have generated Smn minigenes containing either wild-type Smn exon 7 or an altered exon 7 containing the C→T nucleotide transition to mimic SMN2. When expressed in cultured cells or transgenic mice, the wild-type minigene produced only full-length transcripts whereas the modified minigene alternatively spliced exon 7. Furthermore, Smn exon 7 contains a critical AG-rich exonic splice enhancer sequence (ESE) analogous to the human ESE within SMN exon 7, and subtle mutations within the mESE caused a variation in Smn transcript levels. In summary, we show for the first time that the murine Smn locus can be induced to alternatively splice exon 7. These results demonstrate that SMN protein levels can be varied in the mouse by the introduction of specific mutations at the endogenous Smn locus and thereby lay the foundation for developing animals that closely ‘resemble’ SMA patients.

Journal Article.  7068 words.  Illustrated.

Subjects: Genetics and Genomics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.