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The Kessler Lab

Research Interests

Signal transduction and transcriptional mechanisms that pattern the vertebrate embryo.

Research Area

The focus of our research with Xenopus and zebrafish embryos is the development of the primary germ layers that establish the major embryonic cell lineages, and the formation of the Spemann organizer, a specialized group of cells that organizes the body plan. We are using biochemical, molecular, genomic and embryological approaches to address two fundamental questions: 1) What are the transcriptional regulatory pathways that establish and refine pattern in the gastrula; and 2) How is an individual inductive signal used to generate distinct cellular responses during development? In our studies of organizer formation we have identified a transcriptional cascade of activators and repressors that regulate organizer formation and function. Ongoing projects in this area include the analysis of Siamois, Twin, and Goosecoid, homeobox genes required for the developmental functions of the Spemann organizer. In our studies of germ layer formation, we have focused on a TGFß-related inducer, Nodal, which is essential for both mesodermal and endodermal development, and have identified genes that regulate Nodal and the cellular response to Nodal. Ongoing projects address the role of VegT, an essential maternal T-box gene that activates Nodal transcription to induce mesoderm and endoderm. We are also studying Fast1, FoxD3, and Sox17, transcription factors that modulate the expression of Nodal genes and the cellular response to Nodal signals. The ultimate goal of our work is to identify the critical genes and pathways that establish the major lineages and signaling centers of the vertebrate embryo.

Current Members

Kessler, Daniel S. (Principal Investigator/Director) Contact

Additional Information

Lab Rotation Projects A range of projects relating to the induction of the primary germ layers, formation of the Spemann organizer, patterning of the body axis, and transcriptional networks of the gastrula are being pursued using biochemical, molecular, genomic and embryological approaches. Specific projects include: 1. Transcriptional targets of FoxD3 in Nodal regulation and mesoderm induction. 2. Mechanisms of Sox17 control of the endodermal response to Nodal signals. 3. Regulation of TGFß signals and transcriptional targets by Groucho corepressors. 4. Goosecoid repression of Wnt signaling in the Spemann organizer.


Institution: University of Pennsylvania

Web Page:

Personal Phone: 215.898.1478

General/Lab Fax: 215.898.9871