Tissue-dependent isoforms of mammalian Fox-1 homologs are associated with tissue-specific splicing activities

Nucleic Acids Res. 2005 Apr 11;33(7):2078-89. doi: 10.1093/nar/gki338. Print 2005.

Abstract

An intronic hexanucleotide UGCAUG has been shown to play a critical role in the regulation of tissue-specific alternative splicing of pre-mRNAs in a wide range of tissues. Vertebrate Fox-1 has been shown to bind to this element, in a highly sequence-specific manner, through its RNA recognition motif (RRM). In mammals, there are at least two Fox-1-related genes, ataxin-2 binding protein 1 (A2BP1)/Fox-1 and Fxh/Rbm9, which encode an identical RRM. Here, we demonstrate that both mouse Fxh and A2BP1 transcripts undergo tissue-specific alternative splicing, generating protein isoforms specific to brain and muscle. These tissue-specific isoforms are characterized for their abilities to regulate neural cell-specific alternative splicing of a cassette exon, N30, in the non-muscle myosin heavy chain II-B pre-mRNA, previously shown to be regulated through an intronic distal downstream enhancer (IDDE). All Fxh and A2BP1 isoforms with the RRM are capable of binding to the IDDE in vitro through the UGCAUG elements. Each isoform, however, shows quantitative differences in splicing activity and nuclear distribution in transfected cells. All Fxh isoforms and a brain isoform of A2BP1 show a predominant nuclear localization. Brain isoforms of both Fxh and A2BP1 promote N30 splicing much more efficiently than do the muscle-specific isoforms. Skeletal muscles express additional isoforms that lack a part of the RRM. These isoforms are incapable of activating neural cell-specific splicing and, moreover, can inhibit UGCAUG-dependent N30 splicing. These findings suggest that tissue-specific isoforms of Fxh and A2BP1 play an important role in determining tissue specificity of UGCAUG-mediated alternative splicing.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Brain / metabolism
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology*
  • Cell Line
  • Cell Nucleus / chemistry
  • Enhancer Elements, Genetic
  • Exons
  • Humans
  • Introns
  • Mice
  • Molecular Sequence Data
  • Muscle, Skeletal / metabolism
  • Myosin Heavy Chains / genetics
  • Nonmuscle Myosin Type IIB
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • RNA Precursors / chemistry
  • RNA Precursors / metabolism
  • RNA Splicing Factors
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • RNA-Binding Proteins / physiology*
  • Sequence Alignment

Substances

  • Carrier Proteins
  • Protein Isoforms
  • RNA Precursors
  • RNA Splicing Factors
  • RNA, Messenger
  • RNA-Binding Proteins
  • Rbfox1 protein, mouse
  • Rbfox2 protein, mouse
  • Nonmuscle Myosin Type IIB
  • nonmuscle myosin type IIB heavy chain
  • Myosin Heavy Chains

Associated data

  • GENBANK/AY659951
  • GENBANK/AY659952
  • GENBANK/AY659953
  • GENBANK/AY659954
  • GENBANK/AY659955
  • GENBANK/AY659956
  • GENBANK/AY659957
  • GENBANK/AY659958