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. 2018 Aug 10;7:e37267. doi: 10.7554/eLife.37267

Figure 1. The canonical BMP pathway differentially regulates the generation of spinal neurons derived from progenitors that express ASCL1/ATOH1 or NEUROG1/NEUROG2/PTF1a.

(A) Actors of the canonical BMP pathway (BMP7, SMAD1 and SMAD5) known to regulate spinal neurogenesis. (B) Dot-plot representing the spinal neuronal subtypes generated 48 hpe with plasmids producing sh-RNA targeting cBmp7 (sh-B7), cSmad1 (sh-S1) or cSmad5 (sh-S5), comparing the electroporated side to the contra-lateral side. The colour code corresponds to the proneural proteins expressed in the corresponding progenitor domains, as shown in C. (C) Drawing of a transverse section of the developing spinal cord at mid-neurogenesis, highlighting: (left) the neuronal subtypes strongly (white) or moderately (grey) affected by inhibiting canonical BMP activity, and (right) a colour-coded representation of the proneural proteins expressed in the corresponding progenitor domains. (D) Working hypothesis whereby we propose to test if (i) the canonical BMP activity is mediated by ID proteins; (ii) ID proteins act by sequestering E proteins (E, orange), thereby inhibiting the activity of class II HLH/proneural proteins (II, grey); and (iii) E proteins co-operate equally or differentially with the distinct proneural proteins as a function of their preferential binding to specific E-box sequences. .

Figure 1.

Figure 1—figure supplement 1. Inhibiting the canonical BMP pathway affects the generation of ventral spinal neurons.

Figure 1—figure supplement 1.

(A) Diagram of a transverse section of the developing spinal cord at mid-neurogenesis, highlighting the ventral neuron subtypes analysed and the markers used to identify them. (B, C) The proportions (B) and representative images (C) of the ventral spinal neuron subtypes generated 48 hr after in ovo electroporation with a control plasmid or plasmids producing sh-RNAs specifically targeting cBmp7 (sh-Bmp7), cSmad1 (sh-Smad1) or cSmad5 (sh-Smad5). GFP staining (white) and DAPI (blue) are shown to confirm the region of interest was electroporated. The data are presented as the mean ratios ± sem obtained from n = 6–17 embryos per condition; one-way ANOVA + Tukey’s test; *p<0.05.