Endogenous steady-state ion currents, voltage gradients and electric fields produced by ion channels and pumps regulate patterning and have been implicated in adult eye wound healing. So might they play a role in eye development? On p. Michael Levin and co-workers report that transmembrane voltage potential (Vmem) is an important component of the eye induction cascade in Xenopus. The researchers identify a hyperpolarised cluster of cells in the anterior neural field of Xenopus embryos and show that depolarisation of the lineages from which these cells are derived results in malformed eyes. Remarkably, given our understanding of lineage restrictions and plasticity, manipulation of Vmem in non-eye cells induces ectopic eye formation far outside the anterior neural field. Other experiments show that a Ca2+ channel-dependent pathway transduces the Vmem signal and regulates the pattern of eye field transcription factor expression. This new information on the roles of voltage gradients as mediators of patterning during embryogenesis might have implications for the development of regenerative approaches to ocular diseases.
