Effect of Apelin receptor signaling on Nodal activity during mesendoderm development

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The fundamental process in animal development is the miraculous transition of a single cell (the fertilized egg) into the large numbers of diverse cell types that make up our bodies. One of the first steps in this process is the generation of the stem cells that will later make all the cell types of the animal. In the embryo, this process occurs during gastrulation, when there are coordinated cell movements and cell-to-cell communication that generate our body axis and diversify the stem cell populations needed to make the animal. For my research, we study this process using the zebrafish embryo, a fantastic model to examine how early development occurs. Embryos are laid in water, develop rapidly, and are optically clear, allowing us to watch all the cell movements and molecular events that happen during gastrulation and stem cell generation. As we can genetically modify these organisms, we can easily determine how genes regulate this key milestone in animal development. My lab has found that a cell surface receptor, called the Apelin Receptor (Aplnr), influences development at this key stage. In the absence of the Aplnr function, there is a deficit in formation of the precursors of the heart and digestive organs. Our work has shown that Aplnr acts during gastrulation to boost the activity of the Nodal signaling pathway. This is of great interest, as the levels of Nodal signal a cell receives are known to control what path that cell will follow (heart cell, gut cell, neuron, etc.). Aplnr therefore acts as a dial that fine-tunes how much Nodal signal is active at a key stage in development. This gives us a unique opportunity to study how cells decide to become both the right type and right amount of stem cells to allow animal development to occur. We now need to understand how the Aplnr influences Nodal signaling. In this research, we will use the zebrafish embryo to determine how Aplnr activity affects early development and production of the various cell types needed in an animal body. Ultimately, this research will provide fundamental information on how the diversity of cell types found in our bodies is generated. Further, our work will help scientists generate specific cell types required for their research, allowing precise modeling of physiology and development.