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OTTAWA, August 26, 2002 - Researchers from the Ottawa Hospital Research Institute have discovered that a signaling protein called Sonic Hedgehog (SHH), is necessary for the retina to develop properly. The study conducted by the laboratory team of Dr. Valerie Wallace, appears in the August 26 edition of the prestigious journal Nature Neuroscience.

The function of the brain depends, in part, on how neurons (brain cells) are organized. In many regions of the brain, neurons are organized into layers. When a disease or a problem disrupts the process of layering, the brain does not function properly.

The laboratory team of OHRI scientist Dr. Valerie Wallace, is studying how layering takes place in the retina, which is the light sensitive brain tissue located at the back of the eye. In the developing embryo, the retina consists of a single layer of cells, but neurons in the mature retina are organized into three distinct layers.

"We have found that a signaling molecule -- a protein called Sonic Hedgehog -- is produced by a small group of neurons in the developing retina. We've determined that it is required for normal layering, and consequently for proper development and function of the retina," says Dr. Wallace, who is also an Assistant Professor in the Department of Biochemistry, Microbiology and Immunology, and Department of Ophthalmology at the University of Ottawa.

Researchers came to this conclusion when they studied eye development in lab mice that lacked the SHH protein. It resulted in abnormal layering in the retina. Conversely, when retinal cells were grown in the presence of purified SHH, they were able to establish normal layer formation.

Although current studies have only been done on mice, the findings of Dr. Wallace's team could some day lead to gene and cell therapy for the treatment of retinal problems such as macular degeneration, glaucoma or retinitis pigmentosa. However, the findings are not limited to helping understand vision problems alone. They could also lead to a better understanding of the proper development of other areas of the brain, and how breakdowns in the layering process lead to malformations and diseases.

The work of Dr. Wallace's lab would not be possible without the generous support of the National Cancer Institute of Canada, the Canadian Institutes of Health Research, the MS Society of Canada and the E.A. Baker Foundation for the Prevention of Blindness.

Dr. Ron Worton, CEO and Scientific Director of the OHRI, is enthusiastic about the findings. "This is an important discovery for future understanding about health and diseases of the retina and the brain. The persistence and commitment to excellence demonstrated by OHRI staff, such as Dr. Wallace and her laboratory team members, is helping make us the health research institute of choice in Canada," said Dr. Worton.

The Ottawa Hospital Research Institute

The OHRI is the research arm of The Ottawa Hospital, and a major part of the University of Ottawa Faculty of Medicine and Faculty of Health Sciences. Its research programs are grouped into: Molecular Medicine, Cancer Therapeutics, Clinical Epidemiology, Diseases of Aging, Hormones, Growth and Development, Neuroscience, and Vision. With over 100 scientists, 225 students and 400 support staff, and $34 million in external funding, the OHRI is one of the fastest growing, and most respected hospital-based research institutes in Canada.


Ron Vezina, Media Relations Officer, (613) 737-8460

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