In an upcoming paper in the American Journal of Pathology—now available online—Cheng-Ming Chuong, M.D., Ph.D., professor of pathology at the Keck School of Medicine of USC, and his colleagues describe the creation of a mouse in which a particular gene-called noggin-is overexpressed in the skin. (Noggin works by suppressing the action of a protein called bone morphogenic protein, or BMP, which has a key role in a number of developmental pathways in mice and humans alike.)
Because of the role that noggin appears to play in the development of integument (skin and associated features), Chuong and his Keck School colleagues expected to see an increase in the number of hair follicles in the skin of the genetically modified mouse. And that is, indeed, what they saw. Not only was the fur of these mice thicker, with hair follicle density increasing by as much as 80 percent in the transgenic mice, but the transgenic mice also grew more whiskers than normal mice, with several whiskers sprouting from each follicle.
That, however, was only the beginning. The overexpression of the noggin gene also led to some unusual and unexpected changes in the mice. For instance, the meibomian glands in the eyes of the transgenic mice were transformed into follicles with small hairs "pointing inwards toward the cornea," Chuong explains. (Meibomian glands are the oil-producing glands that lubricate the eyelids in humans as well as mice; an infection in the meibomian gland is what we call a stye.)
As if hairy eyes weren't enough, the sweat glands on the footpads of the mice's paws turned into hair-sprouting follicles as well. And some of them sported misshapen c
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Contact: Jon Weiner
jonweine@usc.edu
323-442-2830
University of Southern California
23-Feb-2004