Protein found as link to heart evolution

SAN FRANCISCO, Sept. 8 (UPI) -- U.S. scientists say they've found a specific protein helped the 3-chambered heart of amphibians evolve into the 4-chambered heart of birds and mammals.

Scientists from the Gladstone Institute of Cardiovascular Disease in San Francisco, Swarthmore College and Michigan State University analyzed tissues from animal embryos. They explained the heart of amphibians has three chambers -- one atrium receives deoxygenated blood from the body, while the other atrium receives oxygenated blood from the lungs. Those two streams mix in a single ventricle that pumps incompletely oxygenated blood to the rest of the body.

The researchers noted birds and mammals have two separate ventricles, one pumping deoxygenated blood from the body to the lungs at low pressure, the other pumping highly oxygenated blood from the lungs to the body at high pressure.

The study found the evolution to a four-chambered heart was governed by the distribution of a protein called T-box transcription factor that regulates the expression of specific genes in the embryonic heart.

Professor Benoit Bruneau of the Gladstone Institute says the study's findings will help researchers "understand how a protein like (T-box) is involved in forming the heart and how in the case of congenital heart disease its function is impaired."

The research that included Scott Gilbert of Swarthmore College and Juli Wade of Michigan State University appears in the journal Nature.