University of Michigan
Ann Arbor, MI
Published September 20, 2011
Yukiko Yamashita is a developmental biologist exploring the biochemical, structural, and molecular genetic mechanisms that regulate stem cell division. For most organ systems, complex organisms use small pools of stem cells to replace specialized cells that are injured, infected, or wear out. Yamashita studies the division of stem cells to establish which ones go on to replace differentiated cells and which ones maintain the pool of stem cells for future division. For stem cells in the reproductive tract of fruit flies, the path the dividing cells take is not random, but regulated; newly copied chromosomes eventually differentiate into sperm cells, while the original chromosomes remain within the stem cell pool. Yamashita's research has uncovered several important elements that choreograph this asymmetric division. She and her colleagues have identified specific proteins expressed by support cells that surround each stem cell, providing a spatial frame of reference for the stem cell. Within the dividing cell, chromosome-separating assemblies need to be oriented precisely relative to the support cells for the division to complete — stem cell division stalls if the chromosomes are improperly aligned. Yamashita has extended this result, observing that misalignment occurs more frequently with age, with errors beginning considerably earlier than other, more conventional markers of organism aging would suggest. In addition to insights about the impact of age on stem cell function, Yamashita's basic investigations illuminate the mechanisms underlying the loss of control over stem cell division, which is regarded as the primary cause of many human diseases such as some cancers or other proliferative disorders.
Yukiko Yamashita received a B.S. (1994) and a Ph.D. (1999) from Kyoto University. She was a postdoctoral fellow (2001-2006) in the Department of Developmental Biology at Stanford University prior to joining the faculty of the University of Michigan, where she is currently research assistant professor in the Life Sciences Institute and assistant professor in the Department of Cell and Developmental Biology in the Medical School. Her scientific articles have appeared in such publications as Nature, Science, PLoS One, and the Journal of Cell Science.
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