GRENS, A.; Indiana University South Bend: Conservation of a Developmental Mechanism: Basic-Helix-Loop-Helix Transcription Factors in Cell Fate Specification

Hox genes and their role in patterning is perhaps the most extensively studied example of a conserved molecular mechanism for a developmental process. However, cell fate specification, the commitment of a multipotent cell to one specific cell type or fate, is another crucial process in animal development. The multipotent stem cells of the interstitial cell system of the simple cnidarian Hydra give rise to several differentiated cell types, as do the epithelial stem cells of both the ectoderm and endoderm. Because the cnidarians are basal metazoans, Hydra provides an ideal model system for studying molecular mechanisms of cell fate specification that arose early and have been conserved throughout metazoan evolution. This talk will focus on cell fate specification by the activity of basic-helix-loop-helix transcription factors, which are involved in the specification of cell types ranging from muscle and nerve cells to trophoblasts of the mammalian placenta. The role of members of this family of transcription factors in cell fate specification in Hydra will be reviewed, and evidence for conservation of these roles will be discussed.