Dr. Yoo-Jeong Han, research associate in physiology and biophysics and lead author of the study, determined the DNA sequence of the stretch of the kinase gene that controls how often it is copied, and thus controls the level of kinase in the cell. She found a mutation in the hypertensive animals -- an insertion of a small extra piece of DNA.
The insertion changes the shape of the gene slightly, Han said, making it easier for a transcription factor (another protein that is essentially an on/off switch for genes) to bind and turn on the kinase gene.
"The result is more copies of the gene, more of the kinase in the cell, and, ultimately, more contraction and proliferation of smooth muscle cells," she said.
The transcription factor that binds the mutated gene more easily is part of a cell signalling pathway. This pathway is activated by a protein called Ras, and mutations in Ras have been previously implicated in numerous human cancers.
"When we blocked Ras signalling in the hypertensive rats, we were able to block the proliferation of the smooth muscle cells in the vessel walls and the development of hypertension," said de Lanerolle.
The next question, according to de Lanerolle, is whether a similar mechanism operates in humans to cause essential hypertension.
"If we find a similar mutation in the equivalent human gene, it will make it easier to identify people at risk for developing hypertension," de Lanerolle said. "People with a genetic predisposition to hypertension would be able to lower their risk through behavioral change or, someday, perhaps, drug therapy."
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Contact: Jeanne Galatzer-Levy
jgala@uic.edu
312-996-1583
University of Illinois at Chicago
13-Sep-2006