EAGER: Drosophila pattern repair: an omics view

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

Embryo development is an amazingly complex dance of cells dividing, moving, signaling one another, adopting particular fates and functions, and in some cases dying, taking a fertilized embryo to a fully formed animal. Along this path there are inevitable small errors–too many brain cells, left hand a different size than the right, but these slight fluctuations are repaired by a process called “pattern repair”. Pattern repair is a fundamental process displayed by all animals from fruit flies to humans. Despite the importance of this process, very little is known about how cells manifest pattern repair. The PI’s lab has previously shown that pattern repair in fruit fly embryos is mediated by cell death. All tissues in the developing embryo are endowed with extra cells. Much like musical chairs, when a specific development stage starts (or the music stops), cells in the wrong position die. The goal of this research is to figure out how cells determine which will live and which will die. The problem is that once a cell commits to the cell death pathway, it destroys the signals that caused it to activate the cell death pathway. This project will create fruit flies with known patterning defects that are normally repaired. These embryos will also be defective in cell death; thus they cannot destroy the cell death signals. To accomplish this, a fluorescent reporter for embryos that are cell death defective will be generated. This will allow analysis of the protein changes in cells selected to die. The researchers will continue the “Protein Platoon” program which involves teams of undergraduates conducting authentic protein research. Embryonic pattern formation during development is amazingly robust. This robustness is supported by poorly understood “pattern repair” mechanisms, whereby embryos correct the inevitable random errors in patterning. The PI’s lab has explored two paradigms of pattern repair in Drosophila, referred to as Cell Density Errors and Fate Map Errors. Both mis-patterning scenarios were repaired by a mechanism that causes increased cell death, but not increased mitosis. This proposal is to discover the mechanisms that trigger pattern repair. The overall goal of this project is to generate mis-patterned embryos that are also unable to activate the apoptotic caspase cascade, thus preserving the signals prior to their death. Because blocking apoptosis is lethal, a fluorescent reporter that is expressed very early in development will be generated, well before the start of cell death. This will allow the identification of embryos that are both mis-patterned and cell death defective. Collections of normally patterned embryos that are cell death deficient will be compared to mis-patterned embryos that are cell death deficient using proteomics to identify proteins that change in abundance or post-translational modification. By the completion of this funding period, a set of candidate genes will have been identified that are important for determining how cells decide whether they have the correct neighbors, as required for multicellular organisms to exist, and for the cells in embryos to produce robust, appropriate patterns. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.