AUSTIN, TexasMutations in a gene known as "Fritz" may be responsible for causing human genetic disorders such as Bardet-Biedl syndrome, University of Texas at Austin developmental biologist John Wallingford and Duke University human geneticist and cell biologist Nicholas Katsanis have found.
Their results are published online in this week's edition of Science.
Bardet-Biedl syndrome, and its related Meckel-Gruber syndrome, are two rare but well-studied disorders that result in conditions such as mental retardation, obesity, blindness and kidney failure. This is the first study implicating Fritz's role in human disorders, and the first study of the gene in vertebrates.
Wallingford found that the gene plays a role in two processes in developing embryosfirst, the collective movement of cells as they mold the shape of developing embryos, and second, the creation of cilia, which are projections from cells that serve as sensory antennae.
The Fritz gene regulates these processes by controlling molecules called septins. Septins provide structural support to cell membranes much like metal struts support an umbrella.
Wallingford and his team were pointed toward the role of Fritz in controlling septins by watching time-lapse videos of developing frog embryos with and without the gene.
"Normally, movement of the cell membrane is smooth in developing embryos," said Wallingford, associate professor of biology, "but those embryos without Fritz had cell membranes that were waving and jostling around. Septins basically make a coat across the plasma membrane and stabilize it. Because the membranes looked floppy, the septins are one of the things we looked at."
Lack of the Fritz gene manifested in several ways in the developing embryo. In early stages, embryos had problems associated with collective cell movement and growing longer. That resulted in a number of morphological problems such as defects in the neur
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University of Texas at Austin