Eukaryotic cells face constant challenges to the integrity of their genome from both endogenous and environmental sources, and sophisticated processes have evolved to respond to and minimize long-term DNA damage. Cells employ DNA damage tolerance (DDT) pathways to ensure the completion of DNA replication by filling in gaps created by replication barriers or lesions in the DNA. By allowing replication to continue even in the face of minor lesions, DDT pathways prevent replication forks from stalling, which can lead to fork collapse resulting in serious chromosomal abnormalities and genome instability. Nevertheless, at least one arm of the DNA damage tolerance pathway, known as translesion synthesis (TLS), can be mutagenic, the extent to which depends on the lesion and TLS polymerase involved. Thus, considered broadly, DNA damage tolerance pathways help maintain genome stability but can also promote mutagenesis, which can contribute to cancer and drug resistance. The overall goal of this proposal is to understand the molecular mechanisms that govern damage-specific lesion bypass. In the previous funding period, we identified SHPRH and HLTF as multi-functional proteins that contribute to multiple aspects of DDT pathways in mammalian cells. These proteins exert their effects in a damage-specific manner, responding to alkylation damage and UV damage with complementary specificities, yet the mechanisms by which they act remain undefined. In order to understand how SHPRH and HLTF regulate DNA damage tolerance, we will study their regulation and their role in DDT using a combination of genetic and biochemical approaches.
The first aim of this proposal will address how HLTF and SHPRH are regulated following DNA damage. We will analyze the interaction of HLTF and SHPRH with damaged replication forks, and determine how different types of DNA damage affect the interaction of HLTF and SHPRH with Rad18, another regulator of DDT.
The second aim will address the function and mechanism of action of HLTF and SHPRH in DDT. We will ask how these proteins affect mutagenesis and template switching, the protein composition of stalled forks, and the stability of repeat sequences. Collectively, these studies will provide novel insights into the regulation of two critical regulatory genes that help to minimize mutations arising from replication stress. Both HLTF and SHPRH have been found to be altered in numerous cancers, hence these studies are highly relevant to cancer and other diseases that are modified by genetic mutations.

Public Health Relevance

Accurate and complete replication of DNA is essential to prevent cancer, premature aging and other diseases. This research proposal aims to determine how cells complete replication in the face of different types of replication challenges from a diversity of environmental and endogenous insults. Therefore, this work may ultimately point the way to new approaches for the prevention, detection and treatment of cancer.

National Institute of Health (NIH)
National Institute of Environmental Health Sciences (NIEHS)
Research Project (R01)
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Molecular Genetics A Study Section (MGA)
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Reinlib, Leslie J
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Stanford University
Schools of Medicine
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Zeman, Michelle K; Cimprich, Karlene A (2014) Causes and consequences of replication stress. Nat Cell Biol 16:2-9
Zeman, Michelle K; Lin, Jia-Ren; Freire, Raimundo et al. (2014) DNA damage-specific deubiquitination regulates Rad18 functions to suppress mutagenesis. J Cell Biol 206:183-97
Duursma, Anja M; Driscoll, Robert; Elias, Josh E et al. (2013) A role for the MRN complex in ATR activation via TOPBP1 recruitment. Mol Cell 50:116-22
Machado, Luciana E F; Pustovalova, Yulia; Kile, Andrew C et al. (2013) PHD domain from human SHPRH. J Biomol NMR 56:393-9
Couch, Frank B; Bansbach, Carol E; Driscoll, Robert et al. (2013) ATR phosphorylates SMARCAL1 to prevent replication fork collapse. Genes Dev 27:1610-23
Reuter-Lorenz, Patricia A; Cimprich, Bernadine (2013) Cognitive function and breast cancer: promise and potential insights from functional brain imaging. Breast Cancer Res Treat 137:33-43
Choi, Hyo Jei Claudia; Lin, Jia-Ren; Vannier, Jean-Baptiste et al. (2013) NEK8 links the ATR-regulated replication stress response and S phase CDK activity to renal ciliopathies. Mol Cell 51:423-39
Chen, Jia-Yun; Lin, Jia-Ren; Cimprich, Karlene A et al. (2012) A two-dimensional ERK-AKT signaling code for an NGF-triggered cell-fate decision. Mol Cell 45:196-209
Lin, Jia-Ren; Zeman, Michelle K; Chen, Jia-Yun et al. (2011) SHPRH and HLTF act in a damage-specific manner to coordinate different forms of postreplication repair and prevent mutagenesis. Mol Cell 42:237-49
Van, Christopher; Yan, Shan; Michael, W Matthew et al. (2010) Continued primer synthesis at stalled replication forks contributes to checkpoint activation. J Cell Biol 189:233-46

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