Stem Cell Differentiation

Scientists Shed Light On Inner Workings Of Human Embryonic Stem Cells is a Biocompare article with information about the differentiation of embryonic stem cells. Stem cells can be thought of as general template cells having the potential to go in many different directions. The end result of one form of differntiation could be a liver cell. A kidney cell is another possible result. But what process or processes influence stem cell differentiation? That question is in the minds of many researchers including apparently some at UC Santa Barbara who published results of a study they made in the May 1st issue of Cell.

When reading about stem cells the term pluripotency is a useful word with which to become familiarized. It refers to the potential stem cells have of becoming any one of a variety of different cell types. UC researchers cite a reverse approach to learn how pluripotency operates i.e. starting with a skin cell and transforming it back to a stem cell. There are proteins known as transcription factors which enable the pluripotent property of stem cells. By expressing genes that code for these proteins skin cells can revert back to stem cells.

As one of the researchers noted stem cells have the capacity to replicate and produce more of themselves but can also become something other than stem cells. The new finding indicates that a microRNA, dubbed miR-145, decreases the expression of genes coding for three transcription factors which in turn maintains a stem cell state. Evidently as few as three or four genes can control the maintenance of the stem cell state. There is a transcription factor called OCT4 which is able to repress the promoter for miR-145. MicroRNAs regulating the production of transcription factors and themselves being regulated by another transcription factor- the beauty and complexity of gene regulation affecting the differentiation of stem cells.