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Fig. S4
Utilizing the TetON system for cell type-specific Wnt/β-catenin pathway manipulation.
(a) The TetON system allows for inducible transgene expression. YFP fluorescence (TetResponder transgene) is robustly induced in DOX-treated but not EtOH-treated ubi:TetA AmCyan;TetRE:Axin1-YFP double transgenic animals.
(b) Consistent with Wnt/β-catenin pathway activation, AmCyan fluorescence is undetectable in unlesioned lef1:TetA AmCyan transgenic animals and upregulated after a lesion (arrow).
(c) gfp mRNA (green) and amcyan mRNA (red) are co-expressed in lesioned 6xTCF:dGFP;lef1:TetA AmCyan double transgenic animals, indicating that lef1 regulatory elements drive gene expression in Wnt-responding cells in the lesion site.
(d) DOX treatment of lef1:TetA AmCyan;TetRE:Axin1-YFP double transgenic animals (but not single transgenic control animals) interferes with axin2 expression in non-neural lesion site cells.
(e) Ubiquitous axin1 overexpression through DOX treatment of ubi:TetA AmCyan; TetRE:Axin1-YFP double transgenic animals, interferes with axin2 expression in non-neural lesion site cells.
(f) axin1 overexpression specifically in neurons through DOX treatment of Xla.Tubb:TetA AmCyan;TetRE:Axin1-YFP double transgenic animals does not reduce axin2 expression in non-neuronal lesion site cells.
(g) DOX treatment of Xla.Tubb:TetA AmCyan;TetRE:Axin1-YFP double transgenic animals (but not single transgenic control animals) reduced axin2 expression in a constitutively Wnt-responsive domain in the brain (arrows), indicating that the Xla.Tubb:TetA AmCyan TetActivator line drives functionally relevant axin1 levels in neurons.
(a-g) Views are lateral (dorsal is up, rostral is left). BF: brightfield. Scale bars: whole mounts, 200 μm (g), 100 μm (a-b, d-f) and 25 μm (c).