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Principal Investigator: Lee, Seongmin
Institute Receiving Award University Of Texas At Austin
Location Austin, TX
Grant Number R01ES034781
Funding Organization National Institute of Environmental Health Sciences
Award Funding Period 12 Aug 2023 to 31 May 2028
DESCRIPTION (provided by applicant): ABSTRACT Alkylation DNA damage caused by alkylating agents promotes mutations and cancer development. Guanine N7 is targeted by a wide range of alkylating mutagens, carcinogens, and anticancer agents, producing the cationic N7-alkylguanine (N7-alkylG) adducts as major lesions. These lesions have half-lives of several hours to days in DNA and thus can affect DNA replication and transcription. The positively charged N7-alkylG lesions can also undergo further modification to generate secondary lesions such as alkyl-formamidopyrimidine (alkyl-FapyG) adducts. The recognition, repair, and mutagenesis mechanisms of many mutagen/carcinogen-induced N7- alkylG and alkyl-FapyG lesions, except for a few lesions such as N7-aflatoxin B1-G and aflatoxin B1-FapyG adducts, remain poorly characterized, thereby precluding a complete understanding of the contribution of these major lesions to mutations and cancer development. For example, the mutagenic properties of the predominant N7-alkylG adducts produced by the cancer-promoting styrene oxide are unknown. This knowledge gap has been due in part to the technical difficulty in preparing a site-specific N7-alkylG- and alkyl-FapyG-containing DNA, which is ascribed to the rapid depurination of N7-alkylG nucleosides and the facile isomerization of alkyl- FapyG during solid-phase DNA synthesis. To overcome the stability issue of N7-alkylG nucleosides, we have developed a 2’-fluorine technology that prevents spontaneous depurination by increasing the stability of N7- alkylG nucleosides. To solve the isomerization problem of alkyl-FapyG, we have taken a post-synthetic approach that produces alkyl-FapyG-containing DNA from N7-alkylG-containing DNA. Our preliminary studies show that guanine N7 alkylation can influence base-pairing properties by facilitating the formation of the rare enol tautomer, syn base conformation, and/or intercalation. Our central hypothesis is that N7-alkylG and alkyl- FapyG adducts promote mutations and cancer development by altering the base-pairing properties of the damaged guanine. Our long-term research goal is to elucidate the biological impacts of chemically labile alkylation damages and their secondary lesions using innovative approaches such as the 2’-F chemistry, the polβ host-guest-complex system, and post-synthetic DNA modification. The objective is to dissect the biological consequences of N7-alkylG and alkyl-FapyG lesions induced by potent alkylating mutagens and anticancer agents such as nicotine-specific nitrosamine, styrene oxide, nitrogen mustards, and N-methylbenzyl nitrosamine. To accomplish this objective, we will characterize the base-pairing properties and the recognition, mutagenesis, and repair mechanisms of N7-alkylG and alkyl-FapyG adducts using combined tools of synthetic, biochemical, structural biology, and cellular approaches. The successful execution of the proposed programs will greatly advance our knowledge of the impact of carcinogen/drug-induced N7-alkylG and alkyl-FapyG lesions on the base pair conformation, stability, tautomerism, mutagenesis, recognition, and repair, thereby providing important insights into the alkylation damage-induced mutations and cancer development.
Science Code(s)/Area of Science(s) Primary: 09 - Genome Integrity
Secondary: 03 - Carcinogenesis/Cell Transformation
Publications No publications associated with this grant
Program Officer Daniel Shaughnessy
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