A Genome-wide Screen to Identify Endoreduplication-Specific Factors
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Date
2012-06
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The Ohio State University
Abstract
The cell cycle process called endoreduplication is a specialized form of DNA replication. Cells do not divide and instead continually undergo G and S phase and as a result, increase their ploidy and size. Endoreduplication is important for normal development in cells such as hepatocytes, giant trophoblasts, and megakaryocytes.
However, it has also been discovered that cancer cells utilize endoreduplication in order to escape apoptosis when exposed to chemotherapeutic drugs which inhibit mitosis. Thus, it is important to identify endoreduplication specific genes in order to fully understand the regulation
mechanisms which are essential for development. Moreover, our previous work and work from other labs has demonstrated that endoreduplication uses machinery as well as regulatory mechanisms which are fundamentally different from those used in mitotic replication.
In order to identify endoreduplication-specific factors, I have begun a genome-wide screening of ~12000 Drosophila melanogaster genes, each possessing a human homologue. The basis of the screen is a very powerful tool called the GAL4/UAS system, which has proven invaluable when coupled with the RNA interference (RNAi) pathway. Combining the GAL/UAS
system with UAS>RNAi enables us to test the effects of downregulating each gene. The genome- wide screen consists of two concurrent screens. The first is a screen through endocycling and mitotically cycling tissue to identify endoreduplication specific factors. The second consists of screening for essential genes for the transition from mitotic replication to endoreduplication.
Currently, I have screened 1280 lines and are further studying candidate genes using clonal analysis and flow cytometry techniques. I expect that one percent of the genes (~10 genes) of the 1280 will be related to endoreduplication and estimate that one percent of the Drosophila
genome (~120) will be related to endoreduplication.
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Keywords
Molecular genetics, cancer, endoreduplication, endoreplication, drosophila