Integrin alpha5beta1 and fibronectin regulate polarized cell protrusions required for Xenopus convergence and extension

• Published in: Current biology 2006-05, Vol.16 (9), p.833-844
• Main Authors: Davidson, Lance A, Marsden, Mungo, Keller, Raymond, Desimone, Douglas W
• Format: Article
• Language: English
• Subjects: Animals; Cell Culture Techniques; Cell Polarity - physiology; Cell Shape - physiology; Cell Surface Extensions - physiology; Embryonic Development - physiology; Fibronectins - antagonists & inhibitors; Fibronectins - physiology; Integrin alpha5beta1 - physiology; Oligonucleotides, Antisense; Xenopus
• ISSN: 0960-9822

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. 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 alpha5beta1 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 alpha5beta1 binding to fibronectin, convergence movements still occur but result in convergent thickening instead of convergent extension. 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.