Heart development requires precise coordination of morphogenetic movements with cell fate specification and differentiation. Beh and colleagues have been investigating how this is achieved in ascidian embryos and now report that the forkhead transcription factor FoxF is essential for FGF-induced migration of heart precursor cells in Ciona intestinalis (see p. 3297). In ascidian embryos, FGF signalling, transduced via the MAPK pathway, activates the transcription factor Ets1/2, which is needed for heart tissue specification and cell migration. Beh et al. show that FoxF is rapidly activated in heart precursors in response to FGF signalling, identify the FoxF minimal heart enhancer, and show that Ets1/2 interacts with this in vivo. Expression of a dominant-negative form of FoxF in heart precursor cells, they report, inhibits their migration but not differentiation and results in the formation of an ectopic beating heart in the tail of juveniles. Overall, these results indicate that FoxF is a direct target of FGF signalling and that it mainly regulates heart cell migration.

© 2007.
2007