The researchers also inserted a human mats gene into the line of mats-mutant flies and found that the human gene is able to perform the same function as the fly gene. Additional experiments also revealed that the mats gene is required for normal differentiation of eye cells during the development of the fly's eye.
Lai's team also tackled the tough challenge of discovering how the mats gene is able to suppress the growth of tumors. "We did not find many clues when we compared the sequence of the mats gene with the sequence of other genes in the public databases," Lai says. "But we did find a counterpart to the mats gene in yeast. This yeast counterpart is known to make a protein that forms a complex with a kinase--an enzyme that catalyzes genetic activity--so we wondered if the protein product of our mats gene also could function in this way." Lai was particularly intrigued by the possibility that the protein product of the mats gene could partner with the kinase product of a known tumor-suppressor gene named "wts," which turned out to be the case.
The researchers performed three experiments to test whether the mats and wts genes interact genetically. In the first experiment, they inserted an additional normal mats gene into a line of flies and found no change in the shape of the flys' eyes. In the second experiment, they inserted an additional normal wts gene and found that the fly's eyes were decreased in size and deformed. In the third experiment, they inserted both a mats gene and a wts gene. "We found that mats and wts together can shrink the fly's eye much more dramatically," Lai reports. "Their effect is not additive, but synergistic. The two genes have a more powerful effect when they combine to work together in