Journal of Cell Science 115, e2401-e2401 (2002)
Copyright © 2002 The Company of Biologists Limited
Actin' roles for Ena/VASP proteins
Research into cytoskeletal dynamics has uncovered various actin-binding
proteins, including the Arp2/3 complex, the monomer-binding protein profilin,
capping proteins and Ena/VASP proteins. Over the past few years, the roles of
many of these have become clearer. Ena/VASP proteins, however, have been
implicated in both promotion and inhibition of actin-dependent processes. On
p. 4721, Frank Gertler and
co-workers discuss work that could resolve this apparent paradox, arguing that
differences between whole cell behaviour and that of cell parts can account
for previous contradictory findings. Studies of fibroblast motility, for
example, indicate that Ena/VASP proteins bind to the free barbed ends of actin
filaments in the distal tips of lamellipodia/filopodia, where they antagonize
capping proteins that inhibit filament elongation. Ena/VASP proteins may thus
promote lamellipodial extension but reduce overall motility, since the
lamellipodia generated are unbranched and less stable. Interestingly,
`anticapping' is not the only function of Ena/VASP proteins: studies of
Listeria motility show it requires their profilin-binding activity
instead. An additional function of these proteins might therefore be to
recruit profilin and thereby provide a supply of polymerization-competent
actin monomers for filament nucleation.
Related articles in JCS:
- The Ena/VASP enigma
- Matthias Krause, James E. Bear, Joseph J. Loureiro, and Frank B. Gertler
JCS 2002 115: 4721-4726.
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