Morphogenetic movements are driven by task-specific transcription factor control David R. McClay, Department of Biology, Duke University, Durham, NC 27708 The epithelial-mesenchymal transition (EMT) of skeletogenic cells in the sea urchin embryo occurs at 9 hrs after fertilization. A comprehensive developmental gene regulatory network is known that describes the specification of those cells. Using that network as a guide, each transcription factor in the network was selectively perturbed and then the EMT monitored. It was learned that one transcription factor cassette controls the de-adhesion component of EMT, another controls motility, and still other cassettes control endocytosis, exocytosis, polarity, invasion, and directed cell shape change. The transcription factors involved are used later for a subsequent EMT and may be essential for each EMT event in the embryo. Other morphogenetic events such as invagination of the archenteron, movement of the primordial germ cells into the coelomic pouches, formation and patterning of the mesodermal structures each involve components of the upstream specification gene regulatory network that controls the cell biology of the morphogenetic event. The goal is to define the control devices and discover how they control the morphogenetic movements. In each case some of the upstream transcription factors are known and some of their endpoint targets are known but the full system of each morphogenetic movement is complex and involves a number of network subcircuits, most of which have yet to be discovered.

Morphogenetic movements are driven by task-specific transcription factor control

David R. McClay,

Department of Biology, Duke University, Durham, NC 27708

The epithelial-mesenchymal transition (EMT) of skeletogenic cells in the sea urchin embryo occurs at 9 hrs after fertilization. A comprehensive developmental gene regulatory network is known that describes the specification of those cells. Using that network as a guide, each transcription factor in the network was selectively perturbed and then the EMT monitored. It was learned that one transcription factor cassette controls the de-adhesion component of EMT, another controls motility, and still other cassettes control endocytosis, exocytosis, polarity, invasion, and directed cell shape change. The transcription factors involved are used later for a subsequent EMT and may be essential for each EMT event in the embryo. Other morphogenetic events such as invagination of the archenteron, movement of the primordial germ cells into the coelomic pouches, formation and patterning of the mesodermal structures each involve components of the upstream specification gene regulatory network that controls the cell biology of the morphogenetic event. The goal is to define the control devices and discover how they control the morphogenetic movements. In each case some of the upstream transcription factors are known and some of their endpoint targets are known but the full system of each morphogenetic movement is complex and involves a number of network subcircuits, most of which have yet to be discovered.