Neighboring Cells Modified to Protect Themselves

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dying cells dna

According to a recent study, cells normally self-destruct when permanent glitches take place in their DNA. Programmed cell death, or apoptosis, helps insure that cells with damaged DNA do not grow and duplicate to produce more mutated cells. Therefore, the process of apoptosis helps safeguard and guarantee the survival of the organism.

At the GSA Drosophila Research Conference, TinTin Su, Ph.D., reported that a dying Drosophila melanogaster larvae cell warns neighboring cells that they are in danger of undergoing a similar fate.
Su and her collaborators at the University of Colorado, Boulder, used ionizing radiation (IR) to stimulate DNA damage and apoptosis in cells of the wing imaginal disc, the immature form of the fruit fly's wings. The neighboring cells reacted by activating bantam, a microRNA. Eventually this lead to the neighboring cells becoming e more difficult to damage and kill by IR.

The scientists concluded that the key to this process was the receptor tyrosine kinase Tie. The dying cell's signal turned on Tie, which lead to the activation of the short microRNA molecule bantam.

"Previously the only known role for Tie in fruit flies was in long-range signaling in border cell migration. Although Tie is not required for normal larval development, it becomes necessary for survival after radiation exposure," Su noted.

The dying cell's signaling its neighbors to protect themselves from apoptosis challenges the long believed notion that cells in the surrounding area of dying, irradiated cells become more prone to death. The results of the experiments performed by Su and her research team also accompany and complement prior studies that demonstrated that a larval disc cell's death leads to propagation of cells in the disc.

"If this protective mechanism also operates in mammals, it may affect the results of the sequential use of cytotoxic agents and radiation in cancer therapy," she said.