AUSTIN, Texas—Scientists at The University of Texas at Austin and their colleagues at UT Southwestern Medical Center at Dallas have identified a gene crucial to the development of the heart. When defective, the gene could result in heart defects.
The researchers said they have discovered that when a gene referred to as Bop is absent from a mouse embryo, the heart will not develop normally and the embryo dies. Their findings are posted on the Nature Genetics Web site and will be published in the journal’s May 1 issue.
Dr. Paul D. Gottlieb, director of the School of Biological Sciences at The University of Texas at Austin, said, “We discovered the Bop gene in the course of another study and found that the gene was expressed (turned on) in certain cells of the immune system and in heart and skeletal muscles. Humans have a Bop gene almost identical to that of mice.”
Gottlieb, a professor of molecular genetics and microbiology and a member of The University of Texas at Austin Institute of Cellular and Molecular Biology, and Dr. Deepak Srivastava, an associate professor of pediatrics and molecular biology at UT Southwestern, were both senior authors of the research. Srivastava holds the Joel B. Steinberg, M.D., Chair in Pediatrics at UT Southwestern.
The University of Texas at Austin researchers used genetic engineering technology to try to produce a strain of Bop “knock-out” mice, that is, mice bred entirely without a working copy of the Bop gene. This is roughly equivalent to figuring out what a radiator does by building a car engine without a radiator and then trying to see if — and how well — the engine will run without it.
“We found we could not produce a living, adult mouse without at least one functional copy of the Bop gene,” Gottlieb said. “We found that a mouse embryo without a good Bop gene always had a defective heart. We went on to show that the m-Bop protein (produced by the Bop gene) is likely to work by turning off other genes that must be turned off if the heart is to develop properly.”
Srivastava and his colleagues determined that the missing gene resulted in the failure to develop the right ventricle of the heart, as well as failure of the left ventricle to develop properly.
“Ventricle defects, including the absence of the right or left ventricle, are the most lethal of pediatric heart problems, accounting for nearly 25 percent of all pediatric deaths from heart defects and making congenital heart disease the leading noninfectious cause of death in the first year of life,” said Srivastava.
Key members of the research team were Robert J. Sims III, a fifth-year student in the cellular and molecular biology graduate program at The University of Texas at Austin, and Stephanie A. Pierce, who is in her fourth year at the UT Southwestern Graduate School of Biomedical Sciences and is a research assistant in pediatrics and molecular biology.
“We are continuing to study how the m-Bop protein works to cause proper development and function of the embryonic and adult mouse heart. Our long-term goal is to find out whether mutations in m-Bop cause heart defects in humans, and, if so, whether therapies can be designed to repair such defects,” Gottlieb said.
The study was supported by the National Institute of Allergy and Infectious Diseases, the Texas Higher Education Coordinating Board, the National Heart, Lung and Blood Institute, the March of Dimes, Donald W. Reynolds Cardiovascular Clinical Research Center and Smile Train Inc.
For more information, contact Dr. Paul Gottlieb at The University of Texas at Austin at (512) 232-2690 or Worth Wren Jr. at UT Southwestern at (214) 648-3404.
