We previously used a chemical genetics approach with the larval zebrafish to identify small molecule inhibitors of tissue regeneration. This led to the discovery that glucocorticoids (GC) block early stages of tissue regeneration by the inappropriate activation of the glucocorticoid receptor (GR). We performed a microarray analysis to identify the changes in gene expression associated with beclomethasone dipropionate (BDP) exposure during epimorphic fin regeneration. Oncofetal cripto-1 showed > eight-fold increased expression in BDP-treated regenerates. We hypothesized that the mis-expression of cripto-1 was essential for BDP to block regeneration. Expression of cripto-1 was not elevated in GR morphants in the presence of BDP indicating that cripto-1 induction was GR-dependent. Partial translational suppression of Cripto-1 in the presence of BDP restored tissue regeneration. Retinoic acid exposure prevented increased cripto-1 expression and permitted regeneration in the presence of BDP. We demonstrated that BDP exposure increased cripto-1 expression in mouse embryonic stem cells and that regulation of cripto-1 by GCs is conserved in mammals.
Keywords: AEC, apical epithelial cap; BDP, beclomethasone dipropionate; Beclomethasone dipropionate; Cripto-1; DMSO, dimethyl sulfoxide; EB, embryoid body; ECM, extracellular matrix; EMT, epithelial-to-mesenchymal transition; ERK, extracellular signal-regulated kinase; Epimorphic regeneration; FGF, fibroblast growth factor; GC, glucocorticoid; GR, glucocorticoid receptor; Glucocorticoids; ISH, in situ hybridization; MIAME, Minimum Information About a Microarray Experiment; MO, morpholino oligonucleotide; One-eyed pinhead; RA, retinoic acid; SEM, standard error of the mean; TGF-β, transforming growth factor beta; Zebrafish; dpa, days post-amputation; dpf, days post-fertilization; eSC, embryonic stem cell; hpa, hours post-amputation; hpf, hours post-fertilization; mLIF, murine leukemia inhibitory factor; qRT-PCR, quantitative reverse transcription polymerase chain reaction; zf, zebrafish.