Smn, the spinal muscular atrophy-determining gene product, modulates axon growth and localization of β-actin mRNA in growth cones of motoneurons

Wilfried Rossoll, Sibylle Jablonka, Catia Andreassi, Ann Kathrin Kröning, Kathrin Karle, Umrao R. Monani, Michael Sendtner

Research output: Contribution to journalArticle

454 Scopus citations

Abstract

Spinal muscular atrophy (SMA), a common autosomal recessive form of motoneuron disease in infants and young adults, is caused by mutations in the survival motoneuron 1 (SMN1) gene. The corresponding gene product is part of a multiprotein complex involved in the assembly of spliceosomal small nuclear ribonucleoprotein complexes. It is still not understood why reduced levels of the ubiquitously expressed SMN protein specifically cause motoneuron degeneration. Here, we show that motoneurons isolated from an SMA mouse model exhibit normal survival, but reduced axon growth. Overexpression of Smn or its binding partner, heterogeneous nuclear ribonucleoprotein (hnRNP) R, promotes neurite growth in differentiating PC12 cells. Reduced axon growth in Smn-deficient motoneurons correlates with reduced β-actin protein and mRNA staining in distal axons and growth cones. We also show that hnRNP R associates with the 3′ UTR of β-actin mRNA. Together, these data suggest that a complex of Smn with its binding partner hnRNP R interacts with β-actin mRNA and translocates to axons and growth cones of motoneurons.

Original languageEnglish (US)
Pages (from-to)801-812
Number of pages12
JournalJournal of Cell Biology
Volume163
Issue number4
DOIs
StatePublished - Nov 24 2003

Keywords

  • HnRNP R
  • RNA transport
  • SMA
  • SMN
  • β-actin

ASJC Scopus subject areas

  • Cell Biology

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