Use of transgenic xenopus to analyse thyroid hormone-dependent regulation during metamorphosis

Amphibian metamorphosis is an excellent model for studying T-3 induction of multiple cellular responses in different target tissues. Somatic and germinal transgenesis can now be applied to the model, permitting analysis of gene regulation in integrated systems. We are combining these techniques to analyze neuronal death during metamorphosis. We used a fusion protein of GFP with XR11 (the xenopus homologue of the mammalian anti-apoptotic gene Bcl(2)) expressed from tissue-specific promoters: GFP-xR11 expression significantly prolonged Rohon-Beard neurons survival, and blocked degenerative changes in Mauthner neurons, without modifying motoneuron fate. The selective protection of two neuronal types reveals cell-specific apoptotic pathways and offers novel approaches to analyse T-3 effects during development.