Developmental Gene Regulatory Networks and the Control of Embryonic Patterning


Thursday, March 31, 2011
Redfield Auditorium - 12:00 noon
Dr. Joel Smith
MBL, Josephine Bay Paul Center

How do cells acquire their identities as the embryo develops from a single cell? This must certainly be the oldest question in developmental biology, and it lies at the heart of many other fields as well, not least regenerative biology (how do adult cells acquire new identities?) and cancer biology (what makes them lose it?).

The simple answer: cell identity is driven by the set of genes that are expressed, or not, within a given cell. Thus, cells acquire and maintain distinct identities by the genes that are either active or inactive inside of them. But then, how are specific genes activated or repressed? Genes are turned on or off according to the combined action of the products of other genes. And what about those? Yet other genes control their expression, and so on and so forth. It does not take long to see where this leads. In other words, our simple answer disguises a far more complex situation. To understand our original question we must understand an entire network of regulatory interactions underlying the genomic control of cell identity and function.

I describe the basics elements of an analysis of genomic regulatory networks, for developmental and other systems, based on functional genomics screens, assays, and analyses. A thorough description of the control network explains how complex regulatory interactions, though based around inherently noisy mechanisms of gene expression, lead to the reliable and reproducible expression of pattern formation genes in a model of early embryogenesis, the sea urchin. As our group is interested in fundamental animal control systems, I then describe ongoing efforts to understand the mechanisms driving body axis specification, a central function of animal development and the wellspring of animal diversity. We use the sea anemone, Nematostella vectensis, due to its phylogenetic placement, which makes it highly informative as a model of the deeply conserved elements of the animal axis formation program. In addition, the exceptional experimental tractability of this model system will place it at the forefront of molecular development studies. I conclude by pointing to applications in the areas of regenerative and cancer biology.