We will determine how checkpoints regulate the cell cycle in response to damaged or incompletely replicated DNA during Drosophila development. Studies in cell extracts and unicellular systems have identified checkpoint mechanisms that monitor genomic DNA and modulate cell cycle progression, allowing time for repair and replication. During a metazoan life cycle, checkpoints must operate in the context of profound developmental changes in cell cycle regulation such as the abolishment of gap phases or mitosis. We are using Drosophila melanogaster to determine how known checkpoint mechanisms function during organismal developmental in vivo, and to uncover novel mechanisms not yet seen in other systems. Our initial findings indicate that different mechanisms act to stall mitosis in response to damaged DNA at different stages of Drosophila embryogenesis. The differential use of multiple mechanisms in metazoan development suggests that loss of a regulatory mechanism is more detrimental for one cell type than for another. This simple notion may help us to understand the tissue-specificity of human diseases that result from the loss of a checkpoint or a cell cycle regulator, and thus to design better therapies. Our plans include 4 aims.
Aim 1) We have found that ongoing S phase is inhibited in response to DNA damage by ionizing radiation in a tissue/cell cycle specific manner in the larvae. Mutants in 01/S regulators (e.g Rb and E2F), G2/M regulators (e.g. Cdk1 and mitotic cyclins) and DNA repair proteins will be used to assay the role of these proteins in the inhibition of S phase, and to determine why only certain cells show this response.
Aim 2) We have found that irradiation inhibited not only the entry into mitosis but also the progress through mitosis in Drosophila embryos; prophase becomes lengthened and metaphase anaphase transition becomes delayed. A combination of molecular, genetic and cytological approaches will identify mechanisms that regulate progress through mitosis after irradiation.
Aim 3) We have found that incomplete DNA replication blocks the exit from mitosis via a spindle checkpoint protein and ultimately leads to apoptosis. A combination of genetic and cytological approaches, together with live imaging of chromosomes and mitotic spindles, will be used to uncover mechanisms that link incomplete DNA replication to the spindle checkpoint and to cell death.
Aim 4) We will screen through existing mutagensensitive Drosophila mutants for their ability to regulate mitosis, S phase and cell death after irradiation, in order to uncover novel genes needed for proper response to DNA damage.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Cell Development and Function Integrated Review Group (CDF)
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Zatz, Marion M
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University of Colorado at Boulder
Schools of Arts and Sciences
United States
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Laurenzana, Elizabeth M; Coslo, Denise M; Vigilar, M Veronica et al. (2016) Activation of the Constitutive Androstane Receptor by Monophthalates. Chem Res Toxicol 29:1651-1661
Wichmann, Anita; Uyetake, Lyle; Su, Tin Tin (2010) E2F1 and E2F2 have opposite effects on radiation-induced p53-independent apoptosis in Drosophila. Dev Biol 346:80-9
Garcia, Kristin; Stumpff, Jason; Duncan, Tod et al. (2009) Tyrosines in the kinesin-5 head domain are necessary for phosphorylation by Wee1 and for mitotic spindle integrity. Curr Biol 19:1670-6
Bilak, Amber; Su, Tin Tin (2009) Regulation of Drosophila melanogaster pro-apoptotic gene hid. Apoptosis 14:943-9
Yi, Xia; Lemstra, Willy; Vos, Michel J et al. (2008) A long-term flow cytometry assay to analyze the role of specific genes of Drosophila melanogaster S2 cells in surviving genotoxic stress. Cytometry A 73:637-42
Jaklevic, Burnley; Uyetake, Lyle; Wichmann, Anita et al. (2008) Modulation of ionizing radiation-induced apoptosis by bantam microRNA in Drosophila. Dev Biol 320:122-30
LaRocque, Jeannine R; Jaklevic, Burnley; Su, Tin Tin et al. (2007) Drosophila ATR in double-strand break repair. Genetics 175:1023-33
Jaklevic, Burnley; Uyetake, Lyle; Lemstra, Willy et al. (2006) Contribution of growth and cell cycle checkpoints to radiation survival in Drosophila. Genetics 174:1963-72
de Vries, Hilda I; Uyetake, Lyle; Lemstra, Willy et al. (2005) Grp/DChk1 is required for G2-M checkpoint activation in Drosophila S2 cells, whereas Dmnk/DChk2 is dispensable. J Cell Sci 118:1833-42
Purdy, Amanda; Uyetake, Lyle; Cordeiro, Melissa Garner et al. (2005) Regulation of mitosis in response to damaged or incompletely replicated DNA require different levels of Grapes (Drosophila Chk1). J Cell Sci 118:3305-15

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