[PDF][PDF] Integrin α5β1 and fibronectin regulate polarized cell protrusions required for Xenopus convergence and extension

LA Davidson, M Marsden, R Keller, DW DeSimone - Current biology, 2006 - cell.com
LA Davidson, M Marsden, R Keller, DW DeSimone
Current biology, 2006cell.com
Background Integrin recognition of fibronectin is required for normal gastrulation including
the mediolateral cell intercalation behaviors that drive convergent extension and the
elongation of the frog dorsal axis; however, the cellular and molecular mechanisms involved
are unclear. Results We report that depletion of fibronectin with antisense morpholinos
blocks both convergent extension and mediolateral protrusive behaviors in explant
preparations. Both chronic depletion of fibronectin and acute disruptions of integrin α 5 β 1 …
Background
Integrin recognition of fibronectin is required for normal gastrulation including the mediolateral cell intercalation behaviors that drive convergent extension and the elongation of the frog dorsal axis; however, the cellular and molecular mechanisms involved are unclear.
Results
We report that depletion of fibronectin with antisense morpholinos blocks both convergent extension and mediolateral protrusive behaviors in explant preparations. Both chronic depletion of fibronectin and acute disruptions of integrin α5β1 binding to fibronectin increases the frequency and randomizes the orientation of polarized cellular protrusions, suggesting that integrin-fibronectin interactions normally repress frequent random protrusions in favor of fewer mediolaterally oriented ones. In the absence of integrin α5β1 binding to fibronectin, convergence movements still occur but result in convergent thickening instead of convergent extension.
Conclusions
These findings support a role for integrin signaling in regulating the protrusive activity that drives axial extension. We hypothesize that the planar spatial arrangement of the fibrillar fibronectin matrix, which delineates tissue compartments within the embryo, is critical for promoting productive oriented protrusions in intercalating cells.
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