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Résumé |
Invasion of cells through basement membrane (BM) extracellular matrix barriers is
an important process during organ development and cancer metastasis. Much has been
understood concerning the cell biology of invasion, but the role of cell mechanics
in the invasive process is little studied. During invasion cells breach BM
barriers with actin-rich protrusions. It remains unclear, however, if actin
polymerization applies pushing forces to help break through BM, or if actin
filaments play a passive role as scaffolding for targeting invasive machinery.
Here using the developmental event of anchor cell (AC) invasion in Caenorhabditis
elegans, we observe that the AC deforms the BM just prior to invasion, exerting
forces in the tens of nN range. BM deformation is driven by actin polymerization
nucleated by the Arp2/3 complex and its activators, while formins, crosslinkers
and myosin motor activity are dispensable. Delays in invasion upon actin regulator
loss are not caused by defects in AC polarity, trafficking or secretion, as
appropriate markers are correctly localized in the AC even when actin is reduced
and invasion is disrupted. In addition our preliminary results indicate that the
AC nucleus is deformed during invasion, and the role played by the nucleus in AC
invasion is currently under investigation. Overall cell and nuclear mechanics
emerge from this study as important considerations in BM disruption by invading
cells. |
