Traditional pig breeding has a long cycle and high cost, and there is an urgent need to use new technologies to revitalize the pig breeding industry. The recently emerged CRISPR/Cas9 genome editing technique shows great potential in pig genetic improvement, and has since become a research hotspot. Base editor is a new base editing technology developed based on the CRISPR/Cas9 system, which can achieve targeted mutation of a single base. CRISPR/Cas9 technology is easy to operate and simple to design, but it can lead to DNA double strand breaks, unstable gene structures, and random insertion and deletion of genes, which greatly restricts the application of this technique. Different from CRISPR/Cas9 technique, the single base editing technique does not produce double strand breaks. Therefore, it has higher accuracy and safety for genome editing, and is expected to advance the pig genetic breeding applications. This review summarized the working principle and shortcomings of CRISPR/Cas9 technique, the development and advantages of single base editing, the principles and application characteristics of different base editors and their applications in pig genetic improvement, with the aim to facilitate genome editing-assisted genetic breeding of pig.
Animals ; Swine/genetics* ; Gene Editing ; CRISPR-Cas Systems/genetics* ; DNA Breaks, Double-Stranded

Animals ; Mice ; DNA Repair ; DNA Breaks, Double-Stranded ; DNA/metabolism* ; DNA Damage

The CRISPR system is able to accomplish precise base editing in genomic DNA, but relies on the cellular homology-directed recombination repair pathway and is therefore extremely inefficient. Base editing is a new genome editing technique developed based on the CRISPR/Cas9 system. Two base editors (cytosine base editor and adenine base editor) were developed by fusing catalytically disabled nucleases with different necleobase deaminases. These two base editors are able to perform C>T (G>A) or A>G (T>C) transition without generating DNA double-stranded breaks. The base editing technique has been widely used in gene therapy, animal models construction, precision animal breeding and gene function analysis, providing a powerful tool for basic and applied research. This review summarized the development process, technical advantages, current applications, challenges and perspectives for base editing technique, aiming to help the readers better understand and use the base editing technique.
Adenine ; Animals ; CRISPR-Cas Systems/genetics* ; Cytosine ; DNA Breaks, Double-Stranded ; Gene Editing

Meiosis is an essential step in gametogenesis which is the key process in sexually reproducing organisms as meiotic aberrations may result in infertility. In meiosis, programmed DNA double-strand break (DSB) formation is one of the fundamental processes that are essential for maintaining homolog interactions and correcting segregation of chromosomes. Although the number and distribution of meiotic DSBs are tightly regulated, still abnormalities in DSB formation are known to cause meiotic arrest and infertility. This review is a detailed account of molecular bases of meiotic DSB formation, its evolutionary conservation, and variations in different species. We further reviewed the mutations of DSB formation genes in association with human infertility and also proposed the future directions and strategies about the study of meiotic DSB formation.
DNA Breaks, Double-Stranded ; DNA Repair/genetics* ; Humans ; Infertility/genetics* ; Meiosis/physiology*

Programmed DNA double-strand breaks (DSBs) are necessary for meiosis in mammals. A sufficient number of DSBs ensure the normal pairing/synapsis of homologous chromosomes. Abnormal DSB repair undermines meiosis, leading to sterility in mammals. The DSBs that initiate recombination are repaired as crossovers and noncrossovers, and crossovers are required for correct chromosome separation. Thus, the placement, timing, and frequency of crossover formation must be tightly controlled. Importantly, mutations in many genes related to the formation and repair of DSB result in infertility in humans. These mutations cause nonobstructive azoospermia in men, premature ovarian insufficiency and ovarian dysgenesis in women. Here, we have illustrated the formation and repair of DSB in mammals, summarized major factors influencing the formation of DSB and the theories of crossover regulation.
Animals ; Chromosome Segregation ; DNA Breaks, Double-Stranded ; DNA Repair/physiology* ; Humans ; Mammals/genetics*

DNA double-stranded break (DSB) is one of the most catastrophic damages of genotoxic insult. Inappropriate repair of DNA DSBs results in the loss of genetic information, mutation, and the generation of harmful genomic rearrangements, which predisposes an organism to immunodeficiency, neurological damage, and cancer. The tumor repressor p53 plays a key role in DNA damage response, and has been found to be mutated in 50% of human cancer. p53, p63, and p73 are three members of the p53 gene family. Recent discoveries have shown that human p53 gene encodes at least 12 isoforms. Different p53 members and isoforms play various roles in orchestrating DNA damage response to maintain genomic integrity. This review briefly explores the functions of p53 and its isoforms in DNA DSB repair.
Animals ; DNA Breaks, Double-Stranded ; DNA Repair ; Humans ; Mice ; Protein Isoforms ; physiology ; Tumor Protein p73 ; physiology ; Tumor Suppressor Protein p53 ; genetics ; physiology

DNA damage response (DDR) is essential for maintaining genome stability and protecting cells from tumorigenesis. Ubiquitin and ubiquitin-like modifications play an important role in DDR, from signaling DNA damage to mediating DNA repair. In this report, we found that the E3 ligase ring finger protein 126 (RNF126) was recruited to UV laser micro-irradiation-induced stripes in a RNF8-dependent manner. RNF126 directly interacted with and ubiquitinated another E3 ligase, RNF168. Overexpression of wild type RNF126, but not catalytically-inactive mutant RNF126 (CC229/232AA), diminished ubiquitination of H2A histone family member X (H2AX), and subsequent bleomycin-induced focus formation of total ubiquitin FK2, TP53-binding protein 1 (53BP1), and receptor-associated protein 80 (RAP80). Interestingly, both RNF126 overexpression and RNF126 downregulation compromised homologous recombination (HR)-mediated repair of DNA double-strand breaks (DSBs). Taken together, our findings demonstrate that RNF126 negatively regulates RNF168 function in DDR and its appropriate cellular expression levels are essential for HR-mediated DSB repair.
Carrier Proteins ; metabolism ; Cell Line, Tumor ; DNA Breaks, Double-Stranded ; DNA Repair ; genetics ; DNA-Binding Proteins ; metabolism ; Genomic Instability ; HeLa Cells ; Histones ; metabolism ; Humans ; Nuclear Proteins ; metabolism ; RNA Interference ; RNA, Small Interfering ; genetics ; Signal Transduction ; Tumor Suppressor p53-Binding Protein 1 ; metabolism ; Ubiquitin ; Ubiquitin-Protein Ligases ; genetics ; metabolism ; Ubiquitination

Adult ; Azoospermia/pathology* ; DNA Breaks, Double-Stranded ; DNA Repair ; Humans ; Infertility, Male/pathology* ; Male ; Prophase ; Prostate/pathology* ; Recombination, Genetic ; Synapses/pathology* ; Testis/pathology*

No abstract available.
DNA Breaks, Double-Stranded/radiation effects ; Humans ; Radiation Injuries/*etiology ; Radiation Protection/instrumentation ; Radiation, Ionizing ; Radiotherapy Dosage ; Tomography, X-Ray Computed

Although some mutations are beneficial and are the driving force behind evolution, it is important to maintain DNA integrity and stability because it contains genetic information. However, in the oxygen-rich environment we live in, the DNA molecule is under constant threat from endogenous or exogenous insults. DNA damage could trigger the DNA damage response (DDR), which involves DNA repair, the regulation of cell cycle checkpoints, and the induction of programmed cell death or senescence. Dysregulation of these physiological responses to DNA damage causes developmental defects, neurological defects, premature aging, infertility, immune system defects, and tumors in humans. Some human syndromes are characterized by unique neurological phenotypes including microcephaly, mental retardation, ataxia, neurodegeneration, and neuropathy, suggesting a direct link between genomic instability resulting from defective DDR and neuropathology. In this review, rare human genetic disorders related to abnormal DDR and damage repair with neural defects will be discussed.
Aging ; Aging, Premature ; Ataxia ; Cell Cycle Checkpoints ; Cell Death ; Central Nervous System Diseases ; DNA Breaks, Double-Stranded ; DNA Breaks, Single-Stranded ; DNA Damage* ; DNA Repair ; DNA* ; Genomic Instability ; Humans* ; Immune System ; Infertility ; Intellectual Disability ; Microcephaly ; Neuropathology ; Phenotype