Researchers at the University of California, San Francisco have pinpointed a protein that is critical for maintaining a stem cell's full potential to self-renew and to differentiate. Stem cells lacking the protein were impaired in their ability to divide and make identical copies of themselves, called self-renewal. These cells also lost their capacity to differentiate into key cell types, such as cardiac muscle. The protein, Chd1, acts to keep chromosome strands loosely wound, which permits widespread gene activation in the cell's nucleus.
University of California San Francisco
Researchers at the University of California, San Francisco have designed a safer technique for reprogramming adult cells into a state that resembles embryonic stem cells. This method takes advantage of genetic molecules called microRNAs, which regulate the activity of genes. The original 2007 method for creating reprogrammed cells, called induced pluripotent stem (iPS) cells, relied on inserting four genes, some potentially tumor-causing, into the DNA of an adult cell such as a skin cell.
Researchers at UC, San Francisco developed a novel way of finding out the role of DNA-relatives called microRNA. These molecules are known to turn genes on and off and appear to regulate whether embryonic stem cells remain as stem cells or develop into mature cell types, but learning which genes are controlled by each microRNA has been a challenge. Using this screen, the researchers found 14 microRNAs that speed up cell division; of those, five are commonly found in human embryonic stem cells.
Researchers at University of California, San Francisco found nearly a thousand genes that are expressed differently in different parts of the colon. The colon is constantly renewed via its own stem cells and understanding how these genes are expressed differently as the cells specialize will help understand what happens when this goes wrong as in colon cancer.
Proceedings of the National Academy of Sciences: September 25, 2007
Researchers at UC, San Francisco discovered that membrane proteins that form cell to cell connections also have an important role in controlling how neurons migrate in the brain. Understanding neuronal migration is a critical aspect of cell therapy in the nervous system, as replacement cells will need to be directed to their appropriate site of action. This research project is also an example of how funding work in one field moves along work in another.
Researchers at UC, San Francisco identified a group of genes that are active in embryonic stem cells but not in more differentiated cells. They also developed a technique to find DNA regions that could be important for activating these genes, and identified a factor that directs the production of proteins from genes that contain these regulatory DNA regions. These studies will greatly inform research efforts that rely on maintaining a stem cell's ability to proliferate and to generate the many different cell types in a human body.
Researchers at UC, San Francisco identified a molecule that regulates differentiation of embryonic stem cells. In some cases, small molecules of the genetic material RNA have the ability to turn genes on and off rather than carrying out the normal RNA function of coding for proteins. These small RNAs, called micro RNA or miRNA, are thought to be one way the cell regulates genes that control how stem cells differentiate into mature cell types. In this study, the researchers created genetically altered mouse embryonic stem cells that lack the miRNA DGCR8.
Researchers at UC, San Francisco found that proteins involved in the generation of neurons early in development also help neural stem cells produce neurons after birth. Furthermore, the researchers identified a self-repair mechanism in the brain that relies on these neural stem cells. Understanding how endogenous neural stem cells repair and remodel a mature brain is critical to successful stem cell therapy.
Cell: December 15, 2006