Figure 5.
Strongly Constrained Core Interactions and Weakly Constrained Modulators of the BMP Signaling System
(A and B) Nematostella directive axis network (A) compared to the DV network in Xenopus (B). Blue lines represent transcriptional regulation downstream of BMP signaling and black lines represent protein-protein interactions (putative in case of Nematostella). Xenopus network is modified after (De Robertis and Colozza, 2013; Paulsen et al., 2011). Overlaid blue and black lines represent shuttle function of Chordin.
(C–E) Restricted chordin expression domain (red curves on the left plots) results in BMP signaling on the opposite side of the embryo (relative concentration of BMP ligand-receptor complexes shown as black curves on Cʹ–Eʹ) independent of bmp4 expression localization (blue curve). bmp4 can be expressed uniformly (C), on the chordin side (D), or opposite to it (E). The x axis is normalized with respect to maximal domain length (shown as 2π since the embryo is spherical), and the y axis shows the ratio of ligand-bound receptors (LR) with respect to total receptor concentration (RT).
(F and G) Constrained core regulators versus weakly constrained modulators of BMP signaling in Nematostella (F) and Xenopus (G).
(F) Many parameters describing production, function, and turnover of NvDpp/NvBMP5-8 and NvChd (blue circles) are strongly constrained, while most of the parameters describing production, function, and turnover of NvGDF5-like and NvGrm (orange circles) are weakly constrained. Large orange circle with a 9 corresponds to nine unconstrained parameters related to NvGDF5-like and NvGrm.
(G) Many parameters describing production, function, and turnover of frog BMP4/BMP7, ADMP/BMP2, Chordin, and Tolloid (teal circles) are strongly constrained, while most of the parameters describing production, function, and turnover of BAMBI and SMAD6/7 (pink circles) are weakly constrained. Large pink circle with an 8 corresponds to eight unconstrained parameters related to BAMBI and SMAD6/7. Fold of possible increase of parameter values (log scale) is plotted on the y axis, and fold of possible decrease of parameter values (log scale) is plotted on the x axis. (For details see the Supplemental Experimental Procedures and Figure S5.)
See also Figure S5.