Fig. 1

A zebrafish chemical screen identifies statins as regulators of craniofacial and pectoral fin tendon progenitors. (A) Design of the small-molecule screen. Wild-type embryos were incubated with individual compounds from 32 to 56 hpf and alterations in craniofacial scxa expression were assessed at 56 hpf. (B-E) Craniofacial scxa expression at 56 hpf, after incubation from 32 to 56 hpf (B,C) and at 72 hpf after incubation from 48 to 72 hpf (D,E). Atorvastatin expanded scxa expression in the pharyngeal arches (arrows) compared with controls. (F-I) Pectoral fin scxa:mcherry expression at 56 hpf (F,G) and 72 hpf (H,I) upon incubation from 32 to 56 hpf and 48 to 72 hpf, respectively. Atorvastatin expanded scxa:mcherry expression at the cleithrum base (arrowhead), extending distally to the actinotrichia. (J) qPCR quantification revealed that atorvastatin increased scxa expression at 56 hpf and 72 hpf upon incubation from 32 to 56 hpf and 48 to 72 hpf, respectively, compared with controls. n=4, whole embryo (32-56 hpf) and head region (48-72 hpf); Welch's two-tailed t-test. (K) qPCR quantification revealed that fluvastatin increased col1a2 expression at 72 hpf, after incubation from 32 to 48 hpf compared with controls. The combination of fluvastatin, which is characterized by a shorter half-life and a shortened exposure window (Fig. S2M-R), mitigated the toxic effects observed at 72 hpf with atorvastatin treatment. n=3, head region, Welch's two-tailed t-test. (L) Atorvastatin increased the quantity of craniofacial scxa+ cells at 56 hpf and 72 hpf after incubation from 32 to 56 hpf and 48 to 72 hpf, respectively, compared with controls. (M) Atorvastatin increased the quantity of pectoral fin scxa:mcherry+ cells at 56 hpf and 72 hpf upon incubation from 32 to 56 hpf and 48 to 72 hpf, respectively, compared with controls. (N) Atorvastatin increased the quantity of col1a2+ cells at 80 hpf, after incubation from 32 to 56 hpf compared with controls. (J,K) Data are mean±s.d. (L-N) Red bars indicate mean; individual points represent values for individual embryos; Mann–Whitney-Wilcoxon test. *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001. Ventral (B-E) and lateral (F-I) views, anterior towards the left.