Formins are an important and evolutionarily well conserved class of actin binding
proteins with essential biological functions. Although their molecular roles in actin
regulation have been clearly demonstrated in vitro, their functions at the cellular
or organism levels are still poorly understood. To illustrate this problem, but also
to demonstrate potential ways forward, we focus here on the DAAM group of formins.
In vertebrates, DAAM group members have been demonstrated to be important regulators
of cellular and tissue morphogenesis but, as for all formins, the molecular mechanisms
underlying these morphogenetic functions remain to be uncovered. The genome of the
fruitfly Drosophila encodes a single DAAM gene that is evolutionarily highly conserved.
Recent work on dDAAM has already provided a unique combination of observations and
experimental opportunities unrivalled by any other Drosophila formin. These comprise
in vitro actin polymerisation assays, subcellular studies in culture and in vivo,
and a range of developmental phenotypes revealing a role in tracheal morphogenesis,
axonal growth and muscle organization. At all these levels, future work on dDAAM will
capitalize on the power of fly genetics, raising unique opportunities to advance our
understanding of dDAAM at the systems level, with obvious implications for other formins.
