On BC1 RNA and the fragile X mental retardation protein

Proc Natl Acad Sci U S A. 2008 Jan 15;105(2):734-9. doi: 10.1073/pnas.0710991105. Epub 2008 Jan 9.

Abstract

The fragile X mental retardation protein (FMRP), the functional absence of which causes fragile X syndrome, is an RNA-binding protein that has been implicated in the regulation of local protein synthesis at the synapse. The mechanism of FMRP's interaction with its target mRNAs, however, has remained controversial. In one model, it has been proposed that BC1 RNA, a small non-protein-coding RNA that localizes to synaptodendritic domains, operates as a requisite adaptor by specifically binding to both FMRP and, via direct base-pairing, to FMRP target mRNAs. Other models posit that FMRP interacts with its target mRNAs directly, i.e., in a BC1-independent manner. Here five laboratories independently set out to test the BC1-FMRP model. We report that specific BC1-FMRP interactions could be documented neither in vitro nor in vivo. Interactions between BC1 RNA and FMRP target mRNAs were determined to be of a nonspecific nature. Significantly, the association of FMRP with bona fide target mRNAs was independent of the presence of BC1 RNA in vivo. The combined experimental evidence is discordant with a proposed scenario in which BC1 RNA acts as a bridge between FMRP and its target mRNAs and rather supports a model in which BC1 RNA and FMRP are translational repressors that operate independently.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biotinylation
  • Brain / metabolism
  • Fragile X Mental Retardation Protein / genetics*
  • Gene Expression Regulation
  • Immunoprecipitation
  • Mice
  • Mice, Knockout
  • Nucleic Acid Hybridization
  • Protein Biosynthesis
  • RNA, Messenger / metabolism
  • RNA, Small Cytoplasmic*
  • RNA-Binding Proteins / chemistry

Substances

  • BC1 RNA
  • RNA, Messenger
  • RNA, Small Cytoplasmic
  • RNA-Binding Proteins
  • Fragile X Mental Retardation Protein