The Drosophila fragile X protein functions as a negative regulator in the orb autoregulatory pathway

Dev Cell. 2005 Mar;8(3):331-42. doi: 10.1016/j.devcel.2005.01.011.


Translational regulation of maternal mRNAs in distinct temporal and spatial patterns underlies many key decisions in developing eggs and embryos. In Drosophila, Orb is responsible for mediating the translational activation of mRNAs localized within the developing oocyte. Orb is a germline-specific RNA binding protein and is one of the founding members of the CPEB family of translational regulators. Here we show that Orb associates with the Drosophila Fragile X Mental Retardation (dFMR1) protein as part of a ribonucleoprotein complex that controls the localized translation of mRNAs in developing egg chambers. One of the key orb regulatory targets is orb mRNA, and this autoregulatory activity is critical for ensuring that Orb protein is expressed at high levels in the oocyte. We show that dFMR1 functions as a negative regulator in the orb autoregulatory circuit, downregulating orb mRNA translation.

Publication types

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

MeSH terms

  • Animals
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / embryology
  • Drosophila melanogaster / metabolism
  • Female
  • Fragile X Mental Retardation Protein
  • Oocytes / growth & development*
  • Oocytes / metabolism
  • Oogenesis / genetics
  • Oogenesis / physiology*
  • Protein Binding
  • Protein Biosynthesis*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*


  • Drosophila Proteins
  • FMR1 protein, Drosophila
  • RNA, Messenger
  • RNA-Binding Proteins
  • orb protein, Drosophila
  • Fragile X Mental Retardation Protein