With human embryonic stem cells, Kosik explained that for some time he and his team have been studying a set of control genes called microRNAs. "To really understand microRNAs, the first step is to remember the central dogma of biology DNA is the template for RNA, and RNA is translated to protein. But microRNAs stop at the RNA step and never go on to make a protein."
According to Kosik, it doesn't matter how scientists make or obtain stem cells for research. They can be bona fide human embryonic stem cells (HESC) or induced pluripotent stem cells (IPSC) induced from a skin cell. The microRNA patterns don't "respect" how the cells were made, Kosik said. The team found that all pluripotent stem cells are not identical, but did not differ by how they originated. The scientists found two groups of stem cells, irrespective of origin. MicroRNA profiles proved this.
When looking at microRNA, the overall profile is an extraordinarily good predictor maybe the best predictor of what type of cell you have. "You could be looking through the microscope at a tumor, and you may not be sure about that tumor," said Kosik. "Maybe the tumor is in the brain, but you don't know whether it is a brain tumor, or a metastasis from somewhere else. You can't always tell exactly what type of cells they are.
"The microRNAs will tell you," said Kosik. "Those profiles can tell you the different types of cancer; they can tell you the different types of cells; they can distinguish stem cells from other cells; and they can distinguish skin cells from brain cells. Those profiles, when you look at them in their totality, offer a unique signature that can inform
|Contact: Gail Gallessich|
University of California - Santa Barbara