Gene regulatory network model for specification of the skeletogenic mesoderm lineage

Gene regulatory network model for specification of the skeletogenic mesoderm lineage. A graphic model representing the GRN involved in skeletogenic micromere specification (see for further details). At the top of the model, known maternal transcription factor inputs initiate specification in the micromeres at the 16-cell stage (shown as red cells in the embryo on the right). These cells activate Pmar1 [a transcription factor, (TF) and an obligate repressor], which then represses another repressor (HesC, TF), thereby activating Alx1 (TF), Ets1 (TF), Tbr (TF) and Delta [a ligand (L) for the Notch signal transduction pathway]. Over time, additional genes are activated as the embryo forms the mesenchyme blastula stage (depicted by the lower embryo on the right), at which point the skeletogenic cells (red) are fully specified and ingress into the blastocoel. Light gray indicates endoderm; dark gray indicates nonskeletogenic mesoderm. Modified, with permission, from E. Davidson (http://sugp.caltech.edu/endomes/). γ(2)α, cis regulatory sites of the Tbr transcription factor (TF); Blimp, TF; cβ, cytoplasmic β-catenin; CyP, a differentiation gene (DG); Dri, TF; ECNS, early cytoplasmic nuclearization system; Erg, TF; ES, early signal; Ets, TF; Fox, TF; GSK-3, enzyme in canonical Wnt signal transduction pathway; Hex, TF; Hnf6, TF; L1, transmembrane co-receptor of VEGFR; Msp, DG; nβ, TF; Nr1, neuralized, a ubiquitin ligase; Nucl., nucleus; Otx, TF; r11pm, cis-regulatory module of Delta signal; Sm, skeletal matrix; SoxC, TF; TCF, TF; Tel, TF; Tgif, TF; Ubiq, ubiquitous TF; VEGFR, VEGF signal transduction receptor; Wnt8, a signal in the Wnt signal transduction pathway.

Publication

Evolutionary crossroads in developmental biology: sea urchins. (2011) David R. McClay. Development. 2011 Jul 1;138(13):2639-2648. Figure: F5. All organisms Drosophila melanogaster Homo sapiens

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