Zebrafish as model system for the biological characterization of CK1 inhibitors

Introduction: The CK1 family is involved in a variety of physiological processes by regulating different signaling pathways, including the Wnt/& beta;-catenin, the Hedgehog and the p53 signaling pathways. Mutations or dysregulation of kinases in general and of CK1 in particular are known to promote the development of cancer, neurodegenerative diseases and inflammation. There is increasing evidence that CK1 isoform specific small molecule inhibitors, including CK1 & delta;- and CK1 & epsilon;-specific inhibitors of Wnt production (IWP)-based small molecules with structural similarity to benzimidazole compounds, have promising therapeutic potential.Methods: In this study, we investigated the suitability of the zebrafish model system for the evaluation of such CK1 inhibitors. To this end, the kinetic parameters of human CK1 isoforms were compared with those of zebrafish orthologues. Furthermore, the effects of selective CK1 & delta; inhibition during zebrafish embryonic development were analyzed in vivo.Results: The results revealed that zebrafish CK1 & delta;A and CK1 & delta;B were inhibited as effectively as human CK1 & delta; by compounds G2-2 with IC50 values of 345 and 270 nM for CK1 & delta;A and CK1 & delta;B versus 503 nM for human CK1 & delta; and G2-3 exhibiting IC50 values of 514 and 561 nM for zebrafish CK1 & delta;A and B, and 562 nM for human CK1 & delta;. Furthermore, the effects of selective CK1 & delta; inhibition on zebrafish embryonic development in vivo revealed phenotypic abnormalities indicative of downregulation of CK1 & delta;. Treatment of zebrafish embryos with selected inhibitors resulted in marked phenotypic changes including blood stasis, heart failure, and tail malformations.Conclusion: The results suggest that the zebrafish is a suitable in vivo assay model system for initial studies of the biological relevance of CK1 & delta; inhibition.

Automated summary

The CK1 family plays a role in various physiological processes by regulating different signaling pathways. Mutations or dysregulation of CK1 can lead to the development of cancer, neurodegenerative diseases, and inflammation. CK1 isoform specific small molecule inhibitors, such as IWP-based small molecules, show promise in therapeutic applications.