Identification of genes associated with lens regeneration from the cornea in Xenopus laevis tadpoles

Surgical removal of the lens from larval Xenopus laevis results in a rapid transdifferention of central corneal cells to form a new lens. The trigger for this process is understood to be an induction event arising from the unprecedented contact between the cornea and the vitreous humour that occurs following lens removal. The identity of this trigger is unknown. Here, we have used a functional transgenic approach to show that BMP signalling is required for lens regeneration and a microarray approach to identify genes that are upregulated specifically during this process. Analysis of the array data strongly implicates Wnt signalling and Pitx transcription factors in this process. Pluripotency genes, in contrast, are not upregulated, supporting the idea that corneal cells transdifferentiate without returning to a stem cell state. Furthermore, several genes from the array were expressed in the forming lens during embryogenesis. One of these, nipsnap1, is a known direct target of BMP signalling. We suggest that, as with tail regeneration, activation of multiple developmental signalling pathways could drive lens regeneration from the cornea.

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Day RC, Beck CW