mesenchyme cells of the sea urchin embryo provide a model system for exploring details of an epithelial to mesenchyme transition (EMT). This morphogenetic movement occurs in all organisms that produce, muscle, bone, and other mesenchyme tissues. Curiously, many parts of the EMT process are co-opted and used by metastatic cells often leading to catastrophic consequences. The EMT is highly complex and normally thought to be well controlled. Here, the system will be examined in detail to determine how the EMT is transcriptionally controlled and coordinated under normal circumstances. A developmental Gene Regulatory Network (GRN) was assembled during the previous funding cycles, and 10 transcription factors were discovered to have the proximal responsibility of controlling the EMT. Different subsets of the 10 transcription factors separately control onset of motility, invasive penetration of the basal lamina, de-adhesion, endocytosis, and other components of the EMT. This project will obtain answers to missing information on how the control circuit is activated, how the 10 transcription factors are integrated to coordinately regulate the complex cellular sequence that occurs in an EMT, and how the same control circuit is activated at least twice in development by two different tissues. The project will examine how 12 different cellular events are coordinately timed to sequence the transition. Each function utilizes many proteins and these must fall under the overall control circuitry. Since the same controlling circuit is activated in different cell types just upstream of EMT onset, the discovery f how that cell switches into the EMT circuit will be of great value both in normal embryonic cells, and in various disease states where an EMT launches the dissemination of abnormal cells.

Public Health Relevance

An epithelial-mesenchymal transition (EMT) is one of the first steps in metastasis of all carcinomas, and it is a necessary step in the formation of normal mesenchyme tissues. Studies have shown that much of the biology of the metastatic EMT has been co-opted from the normal EMT sequence. The goal of this project is to assemble the transcriptional circuitry that regulates the normal progression of an EMT in a model organism to understand how this process is controlled at a molecular level.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Project (R01)
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Study Section
Development - 2 Study Section (DEV2)
Program Officer
Mukhopadhyay, Mahua
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Duke University
Schools of Arts and Sciences
United States
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Slota, Leslie A; McClay, David R (2018) Identification of neural transcription factors required for the differentiation of three neuronal subtypes in the sea urchin embryo. Dev Biol 435:138-149
McClay, David R; Miranda, Esther; Feinberg, Stacy L (2018) Neurogenesis in the sea urchin embryo is initiated uniquely in three domains. Development 145:
Martik, Megan L; McClay, David R (2017) New insights from a high-resolution look at gastrulation in the sea urchin, Lytechinus variegatus. Mech Dev 148:3-10
Martik, Megan L; Lyons, Deirdre C; McClay, David R (2016) Developmental gene regulatory networks in sea urchins and what we can learn from them. F1000Res 5:
Warner, Jacob F; Miranda, Esther L; McClay, David R (2016) Contribution of hedgehog signaling to the establishment of left-right asymmetry in the sea urchin. Dev Biol 411:314-324
Israel, Jennifer W; Martik, Megan L; Byrne, Maria et al. (2016) Comparative Developmental Transcriptomics Reveals Rewiring of a Highly Conserved Gene Regulatory Network during a Major Life History Switch in the Sea Urchin Genus Heliocidaris. PLoS Biol 14:e1002391
Martik, Megan L; McClay, David R (2015) Deployment of a retinal determination gene network drives directed cell migration in the sea urchin embryo. Elife 4:
Warner, Jacob F; McClay, David R (2014) Perturbations to the hedgehog pathway in sea urchin embryos. Methods Mol Biol 1128:211-21
Lyons, Deirdre C; Martik, Megan L; Saunders, Lindsay R et al. (2014) Specification to biomineralization: following a single cell type as it constructs a skeleton. Integr Comp Biol 54:723-33
Cheng, Xianrui; Lyons, Deirdre C; Socolar, Joshua E S et al. (2014) Delayed transition to new cell fates during cellular reprogramming. Dev Biol 391:147-57

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