Scientists at U of T and the University Health Network have identified two genes, known as angiotensin converting enzyme (ACE) 1 and 2, with critical roles in heart function – one contributes to heart failure and the other protects against it. Professor Josef Penninger, of medical biophysics and immunology, and Dr. Peter Backx, a physiology and medicine professor at U of T’s Heart & Stroke/Richard Lewar Centre, found that genetically engineered mice carrying the ACE 1, but not the ACE 2 gene, developed cardiovascular disease and impaired heart function. When the two genes were in balance, the mice developed healthy hearts. The study, published in Nature, found that ACE 2 plays a fundamental role in the cardiovascular system of rats, mice and flies – strongly suggesting that the gene is also an important cardiovascular regulator for humans. “What I found interesting is that the hearts in our mice looked like human ones with coronary heart disease,” says Penninger. Their findings can now be used to develop new approaches to heart disease therapy and genetic screening for people at risk for heart disease.