Biologists at New York University have discovered a system by which arandom choice between two distinct cellular fates in the fruit fly eyebecomes firmly established. Surprisingly, the genes involved are known'tumor suppressor genes', i.e. genes that are inactivated in some formsof cancer due to uncontrolled cell proliferation. Because the fly eyeis highly amenable to genetic analysis, these findings, published inthe latest issue of Cell, could help decipher the mechanisms by whichgenes that control cell proliferation and cell growth are themselvesregulated.
In this study, researchers from Dr. Claude Desplan's laboratory inthe Center for Developmental Genetics at NYU Biology used the fly eyeto understand the mechanism that affects the choice betweenphotoreceptors that allows color discrimination: A given colorphotoreceptor can randomly decide to express a blue, or a greenphotopigment, but expressing both would lead to sensory confusion.Therefore, a switch mechanism ensures that photoreceptors make anunambiguous decision. Interestingly, the genes involved in this switchappear to be part of a tumor suppressor pathway.
Researchers have recently uncovered processes by which groupsof genes work together to affect the number and size of cells. Thesegenes are often affected in cancers where cells proliferate in anuncontrolled manner. Less clear, however, are the upstream mechanismsthat control this genetic activity: Understanding the regulation ofthese pathways is essential as it would enhance our ability to controlprocesses by which cancer cells replicate or die. Although thephotoreceptors have long completed their last cell division, theyappear to re-utilize the genetic pathways known to control cellproliferation and cell size to achieve a stable state.
"These genes form a bistable loop that insures a robustcommitment of color photoreceptors that does allow ambiguity," saidDesplan, the study's corresponding author. "This represents anunexpected role for genes known to control cell proliferation and cellgrowth."
The research was supported, in part, by a grant from the National Institutes of Health.
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