(SACRAMENTO, Calif.) Researchers at UC Davis and the University of British Columbia have shed new light on methylation, a critical process that helps control how genes are expressed. Working with placentas, the team discovered that 37 percent of the placental genome has regions of lower methylation, called partially methylated domains (PMDs), in which gene expression is turned off. This differs from most human tissues, in which 70 percent of the genome is highly methylated.
While PMDs have been identified in cell lines, this is the first time they have been found in regular human tissue. In addition to enhancing our understanding of epigenetics, this work could influence cancer research and help illuminate how environmental toxins affect fetal development. The paper was published online this week in the Proceedings of the National Academy of Sciences (PNAS).
Since it was unraveled more than ten years ago, the human genome has been the focus of both popular interest and intense scientific focus. But the genome doesn't act alone; there are many factors that influence whether genes are turned on or off. One of these is an epigenetic process called methylation, in which a group of carbon and hydrogen atoms (a methyl group) attaches to DNA, adjusting how genes are expressed.
"I like to think of epigenetics as a layer on top of your genetic code," said senior author Janine LaSalle, professor of medical microbiology and immunology. "It's not the DNA sequence but it layers on top of that and methylation is the first layer. Those layers provide a lot of information to the cells on where and when to turn on the genes."
How and when genes are activated (or inactivated) can have a profound impact on human development, cancer and the biological legacy of environmental toxins. Prior to this research, PMDs had only been found in cultured cell lines, which led some scientists to wonder if they existed outside the test tu
|Contact: Phyllis Brown|
University of California - Davis Health System