Cutting the cord

Courtesy of B. Monier / University of Cambridge, UK

The paper:
B. Monier et al., “An actomyosin-based barrier inhibits cell mixing at compartmental boundaries in Drosophila embryos,” Nat Cell Biol, 12:60–65, 2010.

The finding:
Like others in their field, Bénédicte Sanson and colleagues from University of Cambridge had been trying to explain how different embryonic cell types stay separate during development. The predominant hypothesis suggested that different adhesion molecules helped sort one cell type from another. “We’d been doing screens and screens [for these molecules] and found none,” says Sanson. But when a movie for an unrelated experiment tracking myosin in a fly embryo ran long, Sanson’s team noticed the GFP-labeled myosin built up at the boundaries between developing cells, suggesting that it was these cords of myosin that kept cells from mixing. “This is essential because these compartments will eventually produce different parts of the body,”...

The steps:
Sanson and colleagues used a laser to inhibit functioning of myosin II (a protein that binds to actin filaments to form contractile fibers) at the boundaries between two cell types. As a result, cells from one compartment crossed over to the other, especially when the cells divided. The research displayed “an important technical advance and an important novel result that has eluded past efforts,” says F1000 Faculty Member Michel Labouesse.

The nuance:
Like a rubber band, the actomyosin gives way to let a dividing cell push into a neighboring compartment, and springs back when the cell division is complete.

The future:
Sanson says her lab plans to investigate the signals that trigger the cells to accumulate this myosin trampoline at boundaries.

F1000 evaluators: V. Vasioukhin (Fred Hutchison) • K. Jacobson (UNC Chapel Hill) • C. Kiecker and A. Lumsden (King’s College London) • A. Yap (Inst Molecular Bioscience) • M. Labouesse (CNRS)

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