Developmental Cell - August 16 2010
A study published this week in "Developmental Cell" by Miguel Manzanares' group at the Spanish National Cardiovascular Research Center (CNIC), in collaboration with Tristan A. Rodriguez's group at the MRC Clinical Sciences Centre in London, demonstrates the differential action of micro RNAs (miRNAs) in the maintenance of stem cells during the early stages of mouse embryonic development. Micro RNAs are single stranded RNA chains between 21 and 25 nucleotides long that regulate the expression of other genes through a variety of mechanisms.
The first two cellular decisions in the development of the fertilized egg cell produce three cell lineages. One -the epiblast- gives rise to the embryo proper, while the other two -the trophoblast and the primitive endoderm- develop into the extraembryonic tissues.
This study shows that the main action of miRNAs in the epiblast is to inhibit apoptosis (programmed cell death), whereas in the trophectoderm and primitive endoderm they are able, through different molecular mechanisms in each tissue, to maintain the undifferentiated stem cell state, conserving developmental potential and blocking differentiation.
As Dr. Manzanares emphasizes, this study demonstrates the existence of fundamental differences in how stem cells, via different miRNAs, maintain their developmental potential in embryonic and extraembryonic tissues.
Thomas Spruce, Barbara Pernaute, Aida Di-Gregorio, Bradley S. Cobb, Matthias Merkenschlager, Miguel Manzanares, and Tristan A. Rodriguez