A U.S. study determined a protein that represses gene transcription also blocks embryonic neural stem cells fromdifferentiating into neurons.

   University of California-San Diego and Howard Hughes Medical Institute researchers focused on a repressor protein called SMRT that previously has been shown to repress gene expression in a number of molecular pathways.

   By creating a strain of "knock-out" mice missing the SMRT gene, the team said it was able to pinpoint significant alterations in brain development in the absence of SMRT.

   The researchers said their findings demonstrated the important role of the protein in preventing premature differentiation of specific brain cells from undifferentiated neural stem cells in utero.

   "By showing SMRT prevents differentiation by maintaining neural stem cells in a basic stem cell state, we now have a target to study further how stem cells restrict themselves from differentiating," said first author Kristen Jepsen of the University of California-San Diego School of Medicine.

   The study is reported in the online issue of the journal Nature.

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