Biomaterial Database

MLH1 Deficiency-Triggered DNA Hyperexcision by Exonuclease 1 Activates the cGAS-STING Pathway. 2021

Junhong Guan, and Changzheng Lu, and Qihuang Jin, and Huiming Lu, and Xiang Chen, and Lei Tian, and Yanbin Zhang, and Janice Ortega, and Junqiu Zhang, and Silvia Siteni, and Mingyi Chen, and Liya Gu, and Jerry W Shay, and Anthony J Davis, and Zhijian J Chen, and Yang-Xin Fu, and Guo-Min Li

Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA.

Tumors with defective mismatch repair (dMMR) are responsive to immunotherapy because of dMMR-induced neoantigens and activation of the cGAS-STING pathway. While neoantigens result from the hypermutable nature of dMMR, it is unknown how dMMR activates the cGAS-STING pathway. We show here that loss of the MutLα subunit MLH1, whose defect is responsible for ~50% of dMMR cancers, results in loss of MutLα-specific regulation of exonuclease 1 (Exo1) during DNA repair. This leads to unrestrained DNA excision by Exo1, which causes increased single-strand DNA formation, RPA exhaustion, DNA breaks, and aberrant DNA repair intermediates. Ultimately, this generates chromosomal abnormalities and the release of nuclear DNA into the cytoplasm, activating the cGAS-STING pathway. In this study, we discovered a hitherto unknown MMR mechanism that modulates genome stability and has implications for cancer therapy.

UI	MeSH Term	Description	Entries
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D009369	Neoplasms	New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.	Benign Neoplasm,Cancer,Malignant Neoplasm,Tumor,Tumors,Benign Neoplasms,Malignancy,Malignant Neoplasms,Neoplasia,Neoplasm,Neoplasms, Benign,Cancers,Malignancies,Neoplasias,Neoplasm, Benign,Neoplasm, Malignant,Neoplasms, Malignant
D009713	Nucleotidyltransferases	A class of enzymes that transfers nucleotidyl residues. EC 2.7.7.	Nucleotidyltransferase
D002869	Chromosome Aberrations	Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.	Autosome Abnormalities,Cytogenetic Aberrations,Abnormalities, Autosome,Abnormalities, Chromosomal,Abnormalities, Chromosome,Chromosomal Aberrations,Chromosome Abnormalities,Cytogenetic Abnormalities,Aberration, Chromosomal,Aberration, Chromosome,Aberration, Cytogenetic,Aberrations, Chromosomal,Aberrations, Chromosome,Aberrations, Cytogenetic,Abnormalities, Cytogenetic,Abnormality, Autosome,Abnormality, Chromosomal,Abnormality, Chromosome,Abnormality, Cytogenetic,Autosome Abnormality,Chromosomal Aberration,Chromosomal Abnormalities,Chromosomal Abnormality,Chromosome Aberration,Chromosome Abnormality,Cytogenetic Aberration,Cytogenetic Abnormality
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004277	DNA, Single-Stranded	A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.	Single-Stranded DNA,DNA, Single Stranded,Single Stranded DNA
D005090	Exodeoxyribonucleases	A family of enzymes that catalyze the exonucleolytic cleavage of DNA. It includes members of the class EC 3.1.11 that produce 5'-phosphomonoesters as cleavage products.	DNA Exonucleases,Exonucleases, DNA
D006367	HeLa Cells	The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for, among other things, VIRUS CULTIVATION and PRECLINICAL DRUG EVALUATION assays.	Cell, HeLa,Cells, HeLa,HeLa Cell
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000070957	MutL Protein Homolog 1	Eukaryotic homolog of the bacterial MutL DNA MISMATCH REPAIR protein. It heterodimerizes with MISMATCH REPAIR ENDONUCLEASE PMS2 to form MutL alpha, which is recruited to DNA mismatch sites by the MUTS DNA MISMATCH-BINDING PROTEIN. Mutations in the human MLH1 gene are associated with COLORECTAL NEOPLASMS, HEREDITARY NONPOLYPOSIS.	COCA2 Protein,Colon Cancer, Nonpolyposis Type 2 Protein,MLH1 Protein,MutL Homolog 1