pdgfra is required cell-autonomously for sclerotome-derived cell migration.

(A) Schematics of endogenous Pdgfra protein and two different loss-of-function variants. Compared to wild-type Pdgfra protein (top), PdgfraΔTK-EGFP (middle) is a secreted decoy receptor with its transmembrane and cytoplasmic domains replaced by EGFP, while PdgfraΔK-EGFP (bottom) is a membrane-bound dominant-negative receptor with only the cytoplasmic domain replaced by EGFP. (B) Schematics of overexpression experiments. Wild-type embryos were injected at the one-cell stage with either hsp:sec-GFP or hsp:pdgfra Δ TK-EGFP plasmids, heat shocked at 18 hpf, and stained and imaged at 24 hpf. (C) Expression of nkx3.1 in embryos at 24 hpf after overexpression of either secreted GFP or PdgfraΔTK-EGFP. Ectopic expression of PdgfraΔTK-EGFP, but not secreted GFP, impairs the migration of nkx3.1 + cells from the sclerotome (arrowhead). n = 20 embryos per staining. (D) Transgenic expression of PdgfraΔK-EGFP (cyan) in nkx3.1:Gal4; UAS:NTR-mCherry (magenta) background at 56 hpf. mCherry + EGFP + cells are mostly restricted in the dorsal or ventral regions of the trunk. A transverse view of a 50 μm region centered on the dashed line is shown on the right, with the neural tube (nt) and notochord (n) outlined by dotted lines. n = 5 embryos. (E) Mosaic expression of Lyn-EGFP or PdgfraΔK-EGFP (cyan) in nkx3.1:Gal4; UAS:NTR-mCherry (magenta) embryos at 50 hpf. In Lyn-EGFP-expressing embryos, EGFP + cells are widely distributed in the trunk both around the notochord (arrowheads) and in the fin fold (notched arrowheads). By contrast, in PdgfraΔK-EGFP-expressing embryos, while mCherry + EGFP − cells can be found around the notochord (arrowheads) and in the fin fold (notched arrowheads), EGFP + cells (arrows) are mostly restricted in the dorsal or ventral regions of the trunk. Transverse views of a 50 μm region centered on the dashed line are shown on the right, with the neural tube (nt) and notochord (n) outlined by dotted lines. The corresponding confocal stacks are shown in S2 Movie. n = 10 embryos per group. (F) Quantification of ...