hnRNP-G promotes exon 7 inclusion of survival motor neuron (SMN) via direct interaction with Htra2-beta1

Hum Mol Genet. 2002 Aug 15;11(17):2037-49. doi: 10.1093/hmg/11.17.2037.


Proximal spinal muscular atrophy (SMA) is a common motor neuron disease caused by homozygous loss of the survival motor neuron gene (SMN1). SMN2, a nearly identical copy of the gene and present in all SMA patients, fails to provide protection from SMA, due to the disruption of an exonic splicing enhancer (ESE) by a single translationally silent nucleotide exchange, which causes alternative splicing of SMN2 exon 7. Identification of splicing factors that stimulate exon 7 inclusion and thereby produce sufficient amounts of full-length transcripts from the SMN2 gene is of great importance for therapy approaches. Here, by use of in vivo splicing assays, we identified the protein hnRNP-G and its paralogue RBM as two novel splicing factors that promote the inclusion of SMN2 exon 7. Moreover, hnRNP-G and RBM non-specifically bind RNA, but directly and specifically bind Htra2-beta1, an SR-like splicing factor which we have previously shown to stimulate inclusion of exon 7 through a direct interaction with the AG-rich ESE in SMN2 exon 7 pre-mRNA. By using deletion mutants of hnRNP-G, we show that the specific protein-protein interaction of hnRNP-G with Htra2-beta1 mediates the inclusion of SMN2 exon 7 rather than the non-specific interaction of hnRNP-G with SMN pre-mRNA. Additionally, we show for the first time that recombinant trans-acting splicing factors such as hnRNP-G and Htra2-beta1 are also effective on endogenous SMN2 transcripts and increase the endogenous SMN protein level. Finally, we suggest a model of how the exon 7 mRNA processing is regulated by the splicing factors identified so far.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / genetics*
  • Animals
  • Cell Line
  • Cyclic AMP Response Element-Binding Protein
  • Enhancer Elements, Genetic
  • Exons / genetics*
  • Heterogeneous-Nuclear Ribonucleoproteins / genetics
  • Heterogeneous-Nuclear Ribonucleoproteins / metabolism*
  • Humans
  • Mice
  • Motor Neurons
  • Muscular Atrophy, Spinal / genetics
  • Muscular Atrophy, Spinal / metabolism*
  • Muscular Atrophy, Spinal / therapy
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / immunology
  • Nerve Tissue Proteins / metabolism*
  • Nuclear Proteins
  • Precipitin Tests
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / immunology
  • RNA-Binding Proteins / metabolism*
  • Recombinant Proteins / metabolism
  • SMN Complex Proteins
  • Serine-Arginine Splicing Factors
  • Survival of Motor Neuron 1 Protein
  • Survival of Motor Neuron 2 Protein
  • Transcription, Genetic
  • Y Chromosome


  • Cyclic AMP Response Element-Binding Protein
  • Heterogeneous-Nuclear Ribonucleoproteins
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • RBMY1A1 protein, human
  • RNA, Messenger
  • RNA-Binding Proteins
  • Rbmy protein, mouse
  • Recombinant Proteins
  • SMN Complex Proteins
  • SMN1 protein, human
  • SMN2 protein, human
  • Smn1 protein, mouse
  • Survival of Motor Neuron 1 Protein
  • Survival of Motor Neuron 2 Protein
  • TRA2B protein, human
  • Serine-Arginine Splicing Factors