المؤلفون: Hsueh-Tzu Shih, Wei-Yi Chen, Hsin-Yen Wang, Tung Chao, Hsien-Da Huang, Chih-Hung Chou, Zee-Fen Chang

المصدر: Cell deathdisease. 13(6)

مصطلحات موضوعية: Cancer Research, Cellular and Molecular Neuroscience, Immunology, Centromere, Mutation, Immunologic Deficiency Syndromes, Animals, Cell Biology, DNA, DNA (Cytosine-5-)-Methyltransferases, DNA Methylation, R-Loop Structures, DNA Damage

الوصف: This study used DNA methyltransferase 3b (DNMT3b) knockout cells and the functional loss of DNMT3b mutation in immunodeficiency-centromeric instability-facial anomalies syndrome (ICF) cells to understand how DNMT3b dysfunction causes genome instability. We demonstrated that R-loops contribute to DNA damages in DNMT3b knockout and ICF cells. More prominent DNA damage signal in DNMT3b knockout cells was due to the loss of DNMT3b expression and the acquirement of p53 mutation. Genome-wide ChIP-sequencing mapped DNA damage sites at satellite repetitive DNA sequences including (peri-)centromere regions. However, the steady-state levels of (peri-)centromeric R-loops were reduced in DNMT3b knockout and ICF cells. Our analysis indicates that XPG and XPF endonucleases-mediated cleavages remove (peri-)centromeric R-loops to generate DNA beaks, causing chromosome instability. DNMT3b dysfunctions clearly increase R-loops susceptibility to the cleavage process. Finally, we showed that DNA double-strand breaks (DSBs) in centromere are probably repaired by error-prone end-joining pathway in ICF cells. Thus, DNMT3 dysfunctions undermine the integrity of centromere by R-loop-mediated DNA damages and repair.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::851fbcdae39a4c102340433ea8832767Test
https://pubmed.ncbi.nlm.nih.gov/35688824Test

المؤلفون: Zee Fen Chang, Zhao Qing Shen, Yu Shan Fan, Tung Chao, Ting Fen Tsai, Pei-Jer Chen, Shih Chin Hsu, Yung-Ming Jeng, Hsueh Tzu Shih

المصدر: Autophagy

مصطلحات موضوعية: 0301 basic medicine, Mitochondrial DNA, Carcinoma, Hepatocellular, DNA damage, ATG5, Active Transport, Cell Nucleus, ENDOG, Mitochondrion, Biology, DNA, Mitochondrial, Genomic Instability, Permeability, Dioxygenases, 03 medical and health sciences, Sequestosome 1, Cell Line, Tumor, Autophagy, Humans, education, Molecular Biology, education.field_of_study, Endodeoxyribonucleases, 030102 biochemistry & molecular biology, Liver Neoplasms, Cell Biology, TFAM, Cell biology, Mitochondria, DNA-Binding Proteins, 030104 developmental biology, Mitochondrial permeability transition pore, Gene Knockdown Techniques, DNA Damage, HeLa Cells, Research Paper

الوصف: Genotoxic insult causes nuclear and mitochondrial DNA damages with macroautophagy/autophagy induction. The role of mitochondrial DNA (mtDNA) damage in the requirement of autophagy for nuclear DNA (nDNA) stability is unclear. Using site-specific DNA damage approaches, we show that specific nDNA damage alone does not require autophagy for repair unless in the presence of mtDNA damage. We provide evidence that after IR exposure-induced mtDNA and nDNA damages, autophagy suppression causes non-apoptotic mitochondrial permeability, by which mitochondrial ENDOG (endonuclease G) is released and translocated to nuclei to sustain nDNA damage in a TET (tet methylcytosine dioxygenase)-dependent manner. Furthermore, blocking lysosome function is sufficient to increase the amount of mtDNA leakage to the cytosol, accompanied by ENDOG-free mitochondrial puncta formation with concurrent ENDOG nuclear accumulation. We proposed that autophagy eliminates the mitochondria specified by mtDNA damage-driven mitochondrial permeability to prevent ENDOG-mediated genome instability. Finally, we showed that HBx, a hepatitis B viral protein capable of suppressing autophagy, also causes mitochondrial permeability-dependent ENDOG mis-localization in nuclei and is linked to hepatitis B virus (HBV)-mediated hepatocellular carcinoma development. Abbreviations: 3-MA: 3-methyladenine; 5-hmC: 5-hydroxymethylcytosine; ACTB: actin beta; ATG5: autophagy related 5; ATM: ATM serine/threonine kinase; DFFB/CAD: DNA fragmentation factor subunit beta; cmtDNA: cytosolic mitochondrial DNA; ConA: concanamycin A; CQ: chloroquine; CsA: cyclosporin A; Dox: doxycycline; DSB: double-strand break; ENDOG: endonuclease G; GFP: green fluorescent protein; Gy: gray; H2AX: H2A.X variant histone; HBV: hepatitis B virus; HBx: hepatitis B virus X protein; HCC: hepatocellular carcinoma; I-PpoI: intron-encoded endonuclease; IR: ionizing radiation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MOMP: mitochondrial outer membrane permeability; mPTP: mitochondrial permeability transition pore; mtDNA: mitochondrial DNA; nDNA: nuclear DNA; 4-OHT: 4-hydroxytamoxifen; rDNA: ribosomal DNA; ROS: reactive oxygen species; SQSTM1/p62: sequestosome 1; TET: tet methylcytosine dioxygenase; TFAM: transcription factor A, mitochondrial; TOMM20: translocase of outer mitochondrial membrane 20; VDAC: voltage dependent anion channel.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6a0b7f8a513e42364bec310a32d8afa8Test
https://pubmed.ncbi.nlm.nih.gov/33465003Test