This is an ongoing project headed by Dr. DiMaio. Senescence is an important tumor suppressor mechanism. Not only does senescence appear to prevent tumor formation in vivo, but it may be possible to mobilize a durable senescence response as a new approach to treat cancer. With the support of this grant, we have developed a new model of cellular senescence induced by transcriptional repression of the human papillomavirus oncogenes in cervical carcinoma cell lines. In contrast to most other models of senescence, senescence induced by HPV repression is rapid, uniform, and synchronous. We will use this model to explore two important aspects of senescence. First, we will determine the molecular mechanism by which the initial growth arrest caused by HPV E7 repression is converted to an irreversible senescent state. We will test the hypothesis that the stable assembly of heterochromatin at repressed promoters is the primary cause of irreversibility. We will use this system to determine how this ~epressive heterochromatin is formed, and we will conduct a genetic screen to identify cellular genes with the ability to either reverse senescence on their own or to cooperate with re-expressed viral oncogenes to reverse senescence. Second, we will conduct a comprehensive genetic and biochemical analysis of the role of cellular microRNAs in determining the senescence phenotype and the pattern of cellular gene expression in senescent cells. In collaboration with Dr. Steitz, we will compare microRNAs activity in two different growth-arrested states, senescence and quiescence. Taken together, these experiments will provide new insights into the molecular mechanisms that establish and maintain the senescent state, and may set the stage for attempts to translate this knowledge into rational new approaches to treat or prevent cancer by modulating the senescence response.

Public Health Relevance

Senescence is an important cellular process that prevents tumor formation and is being explored as a potential new approach to cancer therapy. We are determining the molecular mechanisms that are responsible for the long-term growth arrest that defines senescence, and are exploring the regulatory gene circuits that are responsible for this phenomenon. A better understanding of senescence will allow us to manipulate this process to prevent or treat cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Program Projects (P01)
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Special Emphasis Panel (ZCA1-GRB-S)
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Yale University
New Haven
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Martinez, Ivan; Hayes, Karen E; Barr, Jamie A et al. (2017) An Exportin-1-dependent microRNA biogenesis pathway during human cell quiescence. Proc Natl Acad Sci U S A 114:E4961-E4970
DiMaio, Daniel (2016) Thank You, Edward. Merci, Louis. PLoS Pathog 12:e1005320
Pawlica, Paulina; Moss, Walter N; Steitz, Joan A (2016) Host miRNA degradation by Herpesvirus saimiri small nuclear RNA requires an unstructured interacting region. RNA 22:1181-9
Brown, Jessica A; Kinzig, Charles G; DeGregorio, Suzanne J et al. (2016) Hoogsteen-position pyrimidines promote the stability and function of the MALAT1 RNA triple helix. RNA 22:743-9
Gorres, Kelly L; Daigle, Derek; Mohanram, Sudharshan et al. (2016) Valpromide Inhibits Lytic Cycle Reactivation of Epstein-Barr Virus. MBio 7:e00113
McKenzie, Jessica; Lopez-Giraldez, Francesc; Delecluse, Henri-Jacques et al. (2016) The Epstein-Barr Virus Immunoevasins BCRF1 and BPLF1 Are Expressed by a Mechanism Independent of the Canonical Late Pre-initiation Complex. PLoS Pathog 12:e1006008
Zhang, Wei; Xie, Mingyi; Shu, Mei-Di et al. (2016) A proximity-dependent assay for specific RNA-protein interactions in intact cells. RNA 22:1785-1792
Tycowski, Kazimierz T; Shu, Mei-Di; Steitz, Joan A (2016) Myriad Triple-Helix-Forming Structures in the Transposable Element RNAs of Plants and Fungi. Cell Rep 15:1266-76
Luo, Yong; Motamedi, Nasim; Magaldi, Thomas G et al. (2016) Interaction between Simian Virus 40 Major Capsid Protein VP1 and Cell Surface Ganglioside GM1 Triggers Vacuole Formation. MBio 7:e00297
Brown, Jessica A; Kinzig, Charles G; DeGregorio, Suzanne J et al. (2016) Methyltransferase-like protein 16 binds the 3'-terminal triple helix of MALAT1 long noncoding RNA. Proc Natl Acad Sci U S A 113:14013-14018

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