We know a perturbed DNA damage response during meiosis will result in infertility, pregnancy loss or genetic defects. However, we know very little about the regulation of the DNA damage response during meiosis. My preliminary data implies that the SMC5/6 complex is required to mediate the DNA damage response during meiotic cell cycle progression. Because the SMC5/6 complex is essential for cell viability, in vivo experiments in mammals have not been performed and our understanding of the function of SMC5/6 in mammals is limited. I am creating a germ cell-specific mutation of Smc5 and mutating the testis specific SMC5/6 gene Eid3. These mutants will enable me to perform the first comprehensive studies of SMC5/6 complex function in meiosis (Aim1). EID3 is a testis-specific kleisin subunit of the SMC5/6 complex. However, the somatic cell kleisin SMC5/6 subunit, NSE4, is also expressed within the testis. Therefore, there are two SMC5/6 complexes present within the testis, SMC5/6NSE4 and SMC5/6EID3. I will determine the similarities and differences between the two complexes (Aim 2). I have confirmed that the SMC5/6 complex interacts with the BAT3-EP300 complex. The BAT3-EP300 complex is required for the activation of a TRP53-mediated DNA damage response. According to the protein interaction network developed between the SMC5/6 and the BAT3- EP300 complexes, SMC5/6 emerges as a key component of the DNA damage response pathway, by regulating TRP53 acetylation.
In Aim 3, I will conduct a detailed assessment of the interaction between SMC5/6 and BAT3-EP300, together with biochemical analysis of the antagonistic function of EID3 on BAT3- EP300-mediated TRP53 acetylation. I approach the K99/R00 award with the hypothesis that SMC5/6 acts as a repair/surveillance complex coordinating DNA repair and the TRP53-mediated DNA damage response. This function ensures fidelity at the prophase to metaphase I transition of meiosis.

Public Health Relevance

During the formation of sperm and eggs, chromosomes must segregate accurately. However, approximately 10% of clinically reported pregnancies are chromosomally abnormal, resulting in pregnancy loss or genetic defects such as Down syndrome. Very little is known about the genetic failures that cause these chromosomal abnormalities in sex cells;however, we will significantly enhance our knowledge of this phenomenon by achieving the goals set within this proposal.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Transition Award (R00)
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Special Emphasis Panel (NSS)
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Taymans, Susan
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Johns Hopkins University
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Hwang, G; Verver, D E; Handel, M A et al. (2018) Depletion of SMC5/6 sensitizes male germ cells to DNA damage. Mol Biol Cell :mbcE18070459
Zheng, Yi; Lei, Qijing; Jongejan, Aldo et al. (2018) The influence of retinoic acid-induced differentiation on the radiation response of male germline stem cells. DNA Repair (Amst) 70:55-66
Jordan, Philip W; Eyster, Craig; Chen, Jingrong et al. (2017) Sororin is enriched at the central region of synapsed meiotic chromosomes. Chromosome Res 25:115-128
Hwang, Grace; Sun, Fengyun; O'Brien, Marilyn et al. (2017) SMC5/6 is required for the formation of segregation-competent bivalent chromosomes during meiosis I in mouse oocytes. Development 144:1648-1660
Verver, Dideke E; Hwang, Grace H; Jordan, Philip W et al. (2016) Resolving complex chromosome structures during meiosis: versatile deployment of Smc5/6. Chromosoma 125:15-27
Pryzhkova, Marina V; Jordan, Philip W (2016) Conditional mutation of Smc5 in mouse embryonic stem cells perturbs condensin localization and mitotic progression. J Cell Sci 129:1619-34
Ward, Ayobami; Hopkins, Jessica; Mckay, Matthew et al. (2016) Genetic Interactions Between the Meiosis-Specific Cohesin Components, STAG3, REC8, and RAD21L. G3 (Bethesda) 6:1713-24
Verver, Dideke E; Langedijk, Nathalia S M; Jordan, Philip W et al. (2014) The SMC5/6 complex is involved in crucial processes during human spermatogenesis. Biol Reprod 91:22
Hopkins, Jessica; Hwang, Grace; Jacob, Justin et al. (2014) Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes. PLoS Genet 10:e1004413
Gómez, Rocío; Jordan, Philip W; Viera, Alberto et al. (2013) Dynamic localization of SMC5/6 complex proteins during mammalian meiosis and mitosis suggests functions in distinct chromosome processes. J Cell Sci 126:4239-52

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