June 11, 1999-A team of scientists from the Howard Hughes Medical Institute (HHMI) at Baylor College of Medicine has discovered the gene responsible for triggering embryonic cells in the inner ear to develop into sound- and motion-sensing hair cells.

Huda Zoghbi, HHMI investigator at Baylor, said that this finding raises the possibility of introducing the gene into the inner ear to replenish hair cells lost to age and environmental trauma, two prevalent causes of deafness and balance problems.

The Zoghbi lab found that a mouse gene called Math1 signals precursor cells in the inner ear to become hair cells. This decision occurs during embryonic development at a time when other precursor cells are developing into support cells that surround the hair cells and anchor them in place within the inner ear.

The microscopic hairs that sprout from such cells cover inner ear surfaces like wheat in a Kansas field. When sound or head motion creates ripples across the array of hairs, that motion is translated into nerve impulses that the brain interprets as sound or movement.

Zoghbi, whose main research explores disorders of balance, began this collaboration with Hugo Bellen, also an HHMI investigator at Baylor, in 1996 when he brought to her attention a line of uncoordinated fruit flies that lacked a gene called atonal. The scientists knew that genes for such crucial functions are usually "conserved" throughout the animal kingdom-when one species has such genes, other animals species usually do, too. So they embarked on a search for genes similar to atonal in the mouse, in the hopes of gaining insight into peripheral nervous system development in vertebrates.

Zoghbi's group soon isolated a mouse gene, which they named "Mouse atonal homolog1," or Math1, that was similar to the fly
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
11-Jun-1999