| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 5889646 | Bone | 2015 | 8 Pages |
â¢Sp7 is highly expressed in the active osteoblasts of regenerating zebrafish scales.â¢Sp7 promoter-driven luciferase activity measured in ex-vivo cultured transgenic zebrafish scales is an excellent surrogate readout of osteoblast activity.â¢Screening of a small library revealed osteogenic effects for known (e.g. Bmp-2a) as well as several novel compounds.â¢Ex-vivo scale cultures are superior models to bone cell monocultures since communication pathways between bone cells and matrix are maintained.â¢Ex-vivo cultured scales of Sp7:luciferase zebrafish provide an intermediate throughput model to pre-filter promising compounds for follow-up rodent-based experiments.
Tight interactions among different cell types contributing to bone formation are of key importance in the maintenance of bone homeostasis. Based on the high similarity in responses to (anti)osteogenic signals between zebrafish scales and mammalian bone, we developed and validated a model to screen large numbers of compounds using ex-vivo cultured scales of a sp7:luciferase transgenic zebrafish. This model combines the high predictive value of explant cultures with quick, sensitive, and quantifiable readout converging the effects via various pathways including WNT-signaling, to SP7/osterix promoter activity. Sp7 is pivotal in osteoblast differentiation and activity and its promoter activity provides an excellent surrogate for sp7 expression. Bmp-2a was shown to dose-dependently increase sp7-driven luciferase activity ex vivo. Next, we identified novel effects on bone for 51.7% of the compounds from a small library of WNT-signaling modulators, including a strong osteogenic effect for niclosamide. From all previously characterized compounds, the effect on bone was correctly predicted for 70% of compounds, resulting in a 7% false positive- and 21% false negative rate. The proposed sp7:luciferase zebrafish scale model is unique, powerful and efficient new tool to assess compounds with osteogenic effects, prior to further testing in rodents.
