Research ArticleDevelopment

Mechanical Signals Trigger Myosin II Redistribution and Mesoderm Invagination in Drosophila Embryos

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Science Signaling  14 Apr 2009:
Vol. 2, Issue 66, pp. ra16
DOI: 10.1126/scisignal.2000098

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Poking Cells into Invaginating

Mesoderm invagination is the first step toward building the second of the three layers during embryogenesis. In Drosophila, mesoderm invagination is a two-step process, each step under the control of a specific transcription factor. Pouille et al. provide evidence that the first wave of cell constriction, which is controlled by Snail, triggers a mechanical signal that generates the second wave of cell constriction, which is controlled by Twist, and together these two cell constriction events lead to mesoderm invagination. The mechanical signal from the first constriction wave inhibits endocytosis, which promotes signaling of the secreted protein Fog, and stimulates the redistribution of the motor protein Myosin II. In Drosophila embryos lacking Snail and, thus, lacking this first wave of cell constriction, mesoderm invagination can be restored by mechanical indentation of the embryo at the appropriate time during development or by inhibiting endocytosis with the use of a temperature-sensitive form of dynamin, a protein required for clathrin-mediated endocytosis.