In studies in mice, the researchers discovered that TAFII105, a key component of the transcription machinery, is specific to egg-forming cells in ovaries. The finding emphasizes a newly emerging theme in molecular biology -- that DNA transcription is not standardized throughout cells but is instead adapted to control cell-specific gene expression. The scientists believe that future research is likely to reveal other cell-specific transcription components that ensure that genes are expressed in a customized way according to the needs of each cell.

The finding that TAFII105 is specifically involved in controlling genes for egg formation also hints that some inherited forms of sterility in women may be due to mutations in the TAFII105 gene, said the scientists.

In an article published in the September 14, 2001, issue of the journal Science, Howard Hughes Medical Institute investigator Robert Tjian and colleagues Richard N. Freiman, Shane R. Albright, Shuang Zheng, William C. Sha and Robert E. Hammer detailed how they traced the transcriptional role of TAFII105 to granulosa cells in the ovaries of mice. Granulosa cells surround the developing egg, called the oocyte, and foster its development.

The scientists also used DNA microarrays to explore which genes were switched off in knockout mice that lacked a functional copy of the TAFII105 gene. The TAFII105 protein is one of a family of TAF proteins that are subunits of a large complex called the transcription factor TFIID.

"When TFIID and all its associated factors were discovered ten years ago, we found it in every cell we looked at," said Tjian, who is at the University of California at Berkeley. "We thought it would be invariant from cell to cell, since it was so fundamental to the cells in transcri
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
13-Sep-2001