Thursday, July 13, 2006
Biologists at Washington University in St. Louis have made an important breakthrough in understanding a pathway plant cells take to silence unwanted or extra genes using short bits of RNA. Basically, they have made it possible to see where, and how, the events in the pathway unfold within the cell, and seeing is believing, as the old saying goes.
Craig Pikaard, Ph.D., Washington University professor of biology in Arts & Sciences and his collaborators have described the roles that eight proteins in Arabidopsis plants play in a pathway that brings about DNA methylation, an epigenetic function that involves a chemical modification of cytosine, one of the four chemical subunits of DNA. Without proper DNA methylation, higher organisms from plants to humans have a host of developmental problems, from dwarfing in plants to certain tumors in humans, and death in mice.
One role of DNA methylation is to turn off repetitive genes, such as transposable elements that can move or spread throughout a genome and disrupt other gene functions if left unchecked.
There is also interest in DNA methylation because understanding how some genes are selectively silenced and how silenced alleles can be turned on again may someday have practical benefits.