Document text
Principal Investigator: SANG EUN LEE
Organization: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
Fiscal Year: 2024
Award: $310,000
Funding agency: National Institute of General Medical Sciences
Project Summary
Environmental pollutants and anti-cancer chemicals induce DNA–protein crosslinks (DPCs,
also known as protein adducts) of topoisomerases and other proteins that obstruct almost every
chromatin transaction and lead to mutations, genome instability and cell death if not removed
quickly. Cells thus possess multiple mechanisms to remove DPCs: homologous recombination,
nucleotide excision repair and proteolytic repair that involves proteolysis of bound proteins and
nucleolytic cleavage of peptide-DNA bonds. Among these, proteolytic DPC repair is poorly
defined and there are many questions about this unique collaboration between protease and
nuclease and their substrate recognition.
Using genetic and biochemical approaches, we have discovered that Apn2, the evolutionarily
conserved back-up AP endonuclease, possesses an enzymatic activity unblocking DNA ends
with various 3’ adducts including 2’,3’-cyclic phosphate, monophosphate and tyrosine DNA
conjugates. We also found that Apn2 removes DNA-topoisomerase I crosslinks, the flagship DPC
at 3' termini. The results might explain several puzzling symptoms in mice deleted for APE2, the
metazoan Apn2 homolog, including dys-lymphopoiesis and growth retardation. The results also
underscore the importance of 3’ blocked termini processing for genome maintenance and reveal
unique challenges in removing these toxic DNA lesions in a tractable model system.
Nevertheless, our results also raise a new set of questions about the regulation of Apn2 and APE2
in 3' adduct repair. For instance, we aim to determine how Apn2 recognizes a wide range of 3’
termini with different structural features and how such activities are regulated under unique
cellular and functional contexts. We also want to elucidate the biological significance of Apn2 and
human APE2-dependent Top1cc repair in cellular physology exposed to chemotherapeutics.
Furthermore, we plan to define the roles of Apn2 and its interacting protease(s) in the removal of
toxic DNA protein complexes (DPCs) that form via environmental pollutants and chemicals. The
current proposal will address these important questions using innovative genetic and biochemical
assays and shed light on the fundamental mechanisms of 3’ DNA adduct repair, mutagenesis and
maintenance of chromosomal integrity.
Emerging evidence suggests that accumulated DPCs cause aging, neurodegeneration and
liver cancers. The human homolog of Apn2 is also essential for the viability of BRCA-deficient
breast and ovarian cancer cells. The functional conservation in Top1cc and DPC repair between
yeast and human further underscores the value of the proposed research in setting the foundation
for analyzing the equivalent processes in human. Information gained from our proposed research
plan will not only solve one of the fundamental questions in biological processes associated with
mutagenesis, DNA repair, and genome maintenance, but will also impinge directly on the
management and treatment of patients suffering from several devastating diseases with no clear
treatment option.
Terms: <20-(S)-camptothecine><20S Catalytic Proteasome><20S Core Proteasome><20S Proteasome><20S Proteosome><22-secocamptothecin-21-oic acid lactone 21><AP Endonuclease><APE2><APEXL2><APEXL2 Gene><APF-1><ATP-Dependent Proteolysis Factor 1><Abscission><Address><Aging><Alleles><Allelomorphs><Anti-Cancer Agents><Antineoplastic Agents><Antineoplastic Drugs><Antineoplastics><Apurine-Apyrimidine Endonuclease><Apurinic DNA Endonuclease><Apurinic Endonuclease><Assay><BRCA deficient><BRCA1><BRCA1 Gene Product><BRCA1 Protein><BRCA1 gene><BRCA2><BRCA2 gene><Base Excision Repairs><Binding Proteins><Bioassay><Biochemical><Biochemical Genetics><Biochemistry><Biologic Models><Biological><Biological Assay><Biological Chemistry><Biological Function><Biological Models><Biological Process><Breast Cancer><Breast Cancer 1 Gene><Breast Cancer 1 Gene Product><Breast Cancer 2 Gene><Breast Cancer Type 1 Susceptibility Gene><Breast Cancer Type 1 Susceptibility Protein><Breast Cancer Type 2 Susceptibility Gene><Breast-Ovarian Cancer Protein><Camptothecin><Cancer Drug><Carcinogen-DNA Adducts><Causality><Cell Body><Cell Death><Cell Function><Cell Physiology><Cell Process><Cells><Cellular Function><Cellular Physiology><Cellular Process><Chemicals><Chromatin><Collaborations><Complex><Cyclicity><DNA><DNA Adducts><DNA Base Excision Repair><DNA Damage><DNA Damage Repair><DNA Injury><DNA Nicking-Closing Protein><DNA Nucleases><DNA Polymerases><DNA Recombination><DNA Relaxing Enzyme><DNA Relaxing Protein><DNA Repair><DNA Repair Pathway><DNA Topoisomerase I><DNA Type 1 Topoisomerase><DNA Untwisting Enzyme><DNA Untwisting Protein><DNA lesion><DNA replication fork><DNA-(apurinic or apyrimidinic site) lyase><DNA-Dependent DNA Polymerases><DNA-Dependent RNA Polymerases><DNA-Directed DNA Polymerase><DNA-Directed RNA Polymerase><DNA-protein crosslink><DNase><Deoxyribonucleases><Deoxyribonucleic Acid><Development><Disease><Disease Resistance><Disorder><Early Onset Gene Breast Cancer 1><Early Onset Gene Breast Cancer 2><Early Onset Protein Breast Cancer 1><Environmental Pollutants><Enzyme Gene><Enzymes><Esteroproteases><Etiology><Excision><Exposure to><Extirpation><FANCD1><Formaldehyde><Formic Aldehyde><Foundations><Gene Expression><GeneHomolog><Generalized Growth><Genetic><Genetic Alteration><Genetic Change><Genetic Recombination><Genetic defect><Genetics-Mutagenesis><Genome><Genome Instability><Genomic Instability><Genomics><Growth><HMG-20><Hepatic Cancer><Hereditary Breast Cancer 1><Hereditary Breast Cancer 2><High Mobility Protein 20><Histones><Homolog><Homologous Gene><Homologue><Human><Interruption><Investigation><Laboratories><Ligand Binding Protein><Ligand Binding Protein Gene><Lymphopoiesis><Macropain><Macroxyproteinase><Maintenance><Malignant Breast Neoplasm><Malignant Cell><Malignant Ovarian Neoplasm><Malignant Ovarian Tumor><Malignant Tumor of the Ovary><Malignant neoplasm of liver><Malignant neoplasm of ovary><Methyl Aldehyde><Mice><Mice Mammals><Model System><Modeling><Modern Man><Molecular Genetics><Motor Neuron Disease><Movement><Multicatalytic Proteinase><Murine><Mus><Mutagenesis><Mutagenesis Molecular Biology><Mutation><Neoplastic Disease Chemotherapeutic Agents><Nerve Degeneration><Neuron Degeneration><Nucleotide Excision Repair><Nucleotides><Ovary Cancer><Oxomethane><Pathway interactions><Patients><Peptidases><Peptide Hydrolases><Peptides><Periodicity><Phosphates><Physiologic><Physiological><Process><Property><Prosome><Protease Gene><Proteases><Proteasome><Proteasome Endopeptidase Complex><Protein Binding><Protein Cleavage><Proteinases><Proteins><Proteolysis><Proteolytic Enzymes><Proteosome><RNA Polymerases><RNF53><Reaction><Receptor Protein><Recombination><Regulation><Removal><Repair Complex><Repetitive Element><Repetitive Regions><Repetitive Sequence><Research><Resistance><Rhythmicity><Ribonucleoside Phosphates><Ribonucleotides><Role><Single Strand Break Repair><Stress><Subcellular Process><Surgical Removal><Symptoms><Tail><Technical Expertise><Testing><Therapeutic><Tissue Growth><Topoisomerase><Topoisomerase I><Toxin><Tumor-Specific Treatment Agents><Type I DNA Topoisomerases><Tyrosine><Ubiquitilation><Ubiquitin><Ubiquitination><Ubiquitinoylation><Unscheduled DNA Synthesis><XTH2><Yeasts><adduct><anti-cancer><anti-cancer drug><biologic><body movement><bound protein><brca 1 gene><brca 2 gene><cancer cell><causation><crosslink><degenerative disorder of motor neurons><developmental><disease causation><environmental chemical><environmental contaminant><genetic approach><genetic strategy><genome mutation><homologous recombination><human disease><innovate><innovation><innovative><inorganic phosphate><liver cancer><liver malignancy><lymphocytopoiesis><malignant breast tumor><malignant liver tumor><multicatalytic endopeptidase complex><mutant><necrocytosis><neural degeneration><neurodegeneration><neurodegenerative><neurological degeneration><neuronal degeneration><nicking closing enzyme><nuclease><ontogeny><ovarian cancer><pathway><prevent><preventing><protein complex><receptor><reconstitute><reconstitution><relaxing enzyme><repair><repaired><replication fork><resection><resistance to disease><resistance to therapy><resistant><resistant disease><resistant to disease><resistant to therapy><response><seal><social role><swivelase><technical skills><therapeutic resistance><therapy resistant><treatment resistance><ubiquination><ubiquitin conjugation><untwisting enzyme>