Axonal-SMN (a-SMN), a protein isoform of the survival motor neuron is specifically involved in axonogenesis

Veronica Setola, Mineko Terao, Denise Locatelli, Stefania Bassanini, Enrico Garattiini, Giorgio Battaglia

Research output: Contribution to journalArticlepeer-review


Spinal muscular atrophy (SMA) is an autosomal recessive disease of childhood due to loss of the telomeric survival motor neuron gene, SMN1. The general functions of the main SMN1 protein product, full-length SMN (FL-SMN), do not explain the selective motoneuronal loss of SMA. We identified axonal-SMN (a-SMN), an alternatively spliced SMN form, preferentially encoded by the SMN1 gene in humans. The a-SMN transcript and protein are down-regulated during early development in different tissues. In the spinal cord, the a-SMN protein is selectively expressed in motor neurons and mainly localized in axons. Forced expression of a-SMN stimulates motor neuron axonogenesis in a time-dependent fashion and induces axonal-like growth in non-neuronal cells. Exons 2b and 3 are essential for the axonogenic effects. This discovery indicates an unexpected complexity of the SMN gene system and may help in understanding the pathogenesis of SMA.

Original languageEnglish
Pages (from-to)1959-1964
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number6
Publication statusPublished - Feb 6 2007


  • Alternative splicing
  • Axonal sprouting
  • Intron retention
  • Neurodegeneration
  • Spinal muscular atrophy

ASJC Scopus subject areas

  • General
  • Genetics


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