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Fig. 1 Fbxw7 regulates OPC specification and OL myelination in the zebrafish spinal cord. a Spinal cords of fbxw7vo86 and WT controls in (top) Tg(mbp:eGFP-caax), (middle) Tg(olig2:dsRED), and (bottom) Tg(mbp:nls-eGFP) transgenic backgrounds at 3 and 5 days post-fertilization (dpf; dotted-line delineates dorsal and ventral spinal cord tracts). b mbp RNA levels evaluated by qRT-PCR in 5 dpf fbxw7vo86 and WT control whole larvae. Mean ± SEM, N = 3 (larvae). Statistical significance determined by unpaired, two-tailed Student’s t test. c Quantification of olig2:dsRED+ cells/body segment in the dorsal spinal cord at 2, 3, and 5 dpf. Mean ± SEM, N = 7 (larvae). Statistical significance determined by two-way ANOVA. d Quantification of mbp:nls-eGFP+ OLs in the dorsal spinal cord/body segment at 3 dpf. Mean ± SEM, N = 7 (larvae). Statistical significance determined by unpaired, two-tailed Student’s t test. e mbp-nls:eGFP+ OLs from Fig. 1d were divided by the average number of olig2:dsRED+ cells/body segments in dorsal spinal cord at 3 dpf from Fig. 1c. Mean ± SEM, statistical significance determined by unpaired, two-tailed Student’s t test. f Spinal cords of fbxw7vo86 and WT control zebrafish in Tg(mbp:eGFP-caax) and Tg(mbp:nls-eGFP) transgenic backgrounds live-imaged at 3 dpf. Solid arrowheads denote OL somas, hollow arrowheads denote neuronal cell body wrapping. g Representative image of an fbxw7vo86 larva in Tg(mbp:eGFP-caax) (white) and Tg(nbt:dsRED) (magenta) backgrounds showing neuronal cell bodies in the spinal cord wrapped in mbp+ membrane. h Quantification of wrapped neuronal cell bodies in the spinal cord in both fbxw7vo86 and WT controls at 3 dpf. Mean ± SEM, N = 5 (larvae). Statistical significance determined by unpaired, two-tailed Student’s t test. i Representative images of individual labeled OLs from cell-type specific CRISPR-Cas9 knock-down of fbxw7 in sox10 expressing cells in the zebrafish spinal cord at 6 dpf. The UAS-nlscas9-P2A-TagRFPT-caax construct allows visualization of Cas9-expressing cells. j Quantification of average sheath length and k number per OL in controls and with fbxw7 knockdown. Mean ± SEM, Control N = 47 (cells from 40 animals), sgRNAfbxw7 N = 36 (cells from 29 animals). Statistical significance determined by unpaired, two-tailed Student’s t test. Created in BioRender. Emery, B. (2024) BioRender.com/o45h010.