Article: Transcription factors help distinguish humans

By Melissa Lee Phillips

NEWSTranscription factors help distinguish humans
Most gene expression is under stabilizing selection in primates, but humans
show directional evolution of regulatory genes

[Published 9th March 2006 05:00 PM GMT]

Transcription factor expression levels are evolving faster in humans than in
other primates, reports a study in this week's Nature. Since transcription
factors affect the actions of many downstream genes, rapid evolution of
transcription factor expression may in part underlie the dramatic phenotypic
differences between humans and chimpanzees, according to the authors.

"It helps to explain the paradox of very few changes in the protein-coding
complement of the genome" between humans and chimpanzees, said senior author
Kevin White of Yale University. "That has to be responsible for major
changes in morphology and in lifestyle."

Led by first author Yoav Gilad, now at the University of Chicago, the
authors created a multi-species DNA microarray of 1,056 corresponding genes
expressed in the liver of four primate species: humans, chimpanzees,
orangutans, and rhesus macaques.

The authors picked out genes that were expressed at a different level in
humans than in the other three primates, indicating that the genes'
expression went through directional selection in the 5 million years since
humans diverged from chimpanzees. A disproportionate number of the 14 genes
with higher expression in humans coded for transcription factors. Among the
five genes with lower expression in humans, none were transcription factors.

In addition, there was no excess of transcription factors among genes
upregulated in chimpanzees. "They don't evolve at any different rate than
other classes of proteins," White said. "That's what's kind of cool about
this result -- it seems very specific to the human lineage."

Full Text at TheScientist
http://www.the-scientist.com/news/display/23219/

Posted by
Robert Karl Stonjek


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