Genetic switch behind heart muscle's growth discovered

Researchers from Centre for Genomic Regulation (CRG) in Barcelona, Spain, have found a unique genetic switch that appears to guide stem cells so that they develop into specialised heart muscle.

Led by epigeneticist Dr Luciano Di Croce, the team found a protein known as Mel18 that is responsible for regulating a piece of cellular machinery that applies temporary silencers to the DNA in developing cells.

This protein is normally active in a group of embryonic stem cells in the mesoderm -- a layer in the embryo that develops into all the muscles and red blood cells in the body.

"Faults in the production of the protein called Mel18 in early cardiac cells may play a role in heart defects," noted Dr Croce.

However, the researchers found that Mel18 also serves another unexpected function by turning on particular genes as the cardiac cells begin to develop in the mesoderm.

Together, this dual functionality appears to result in the growth of healthy heart tissue.

Harnessing Mel18 also promises to make it easier to grow functioning heart cells in the laboratory from induced pluripotent stem cells or iPS cells.

The findings, published in the journal Cell Stem Cell, could help reveal the underlying causes of heart defects in congenital heart diseases.

They may also lead to new ways of controlling stem cells in the laboratory to grow cellular repair kits for patients with damaged hearts.