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    Peter J. McKinnon, PhD

    Peter J. McKinnon, PhD

    Scythe balances life and death during development

    A protein called Scythe determines which cells live and which die during the growth and development of the mammalian embryo, according to St. Jude researchers.

    The study is the first to show that Scythe plays a critical role during development of mammals by selectively regulating when and where specific cells either proliferate or undergo apoptosis, the process by which cells self-destruct. Understanding how Scythe balances apoptosis with cell proliferation could provide significant insights into how organs develop in the growing embryo.

    The St. Jude team showed in laboratory models that in the absence of Scythe the lungs, kidneys and brain develop abnormally and the embryo cannot survive. These defects were caused by the loss of control over both the multiplication of some cells and the process of apoptosis.

    Normally, there is a balance between life and death in the embryo as the various parts of specific organs get “sculpted” out of the growing mass of cells and some cells are eliminated, according to Peter McKinnon, PhD, Genetics and Tumor Cell Biology. But cells in certain organs of models lacking both copies of the Scythe gene (Scythe-/-) either failed to receive or failed to respond to signals triggering proliferation or apoptosis, he said. The resulting organs were malformed and unable to function properly. McKinnon is senior author of a report on this work that appears in Molecular and Cellular Biology.

    “Our evidence suggests that Scythe might regulate the signaling molecules that are involved in either apoptosis or cell proliferation,” said Fabienne Desmots formerly of Genetics and Tumor Cell Biology, who did much of the work on this project.

    Other authors of the study include Helen Russell, PhD, and Youngsoo Lee, PhD, of Genetics and Tumor Cell Biology; and Kelli Boyd, DVM, PhD, ARC.


    Last update: January 2006