Post-meiotic DNA double-strand breaks occur in <i>Tetrahymena</i>, and require Topoisomerase II and Spo11.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28621664.
- Also identified by DOI 10.7554/eLife.26176 and PMC identifier 5482572.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Based on observations of markers for DNA lesions, such as phosphorylated histone H2AX (γH2AX) and open DNA ends, it has been suggested that post-meiotic DNA double-strand breaks (PM-DSBs) enable chromatin remodeling during animal spermiogenesis. However, the existence of PM-DSBs is unconfirmed, and the mechanism responsible for their formation is unclear. Here, we report the first direct observation of programmed PM-DSBs via the electrophoretic separation of DSB-generated DNA fragments in the ciliate <i>Tetrahymena thermophila</i>. These PM-DSBs are accompanied by switching from a heterochromatic to euchromatic chromatin structure in the haploid pronucleus. Both a topoisomerase II paralog with exclusive pronuclear expression and Spo11 are prerequisites for PM-DSB induction. Reduced PM-DSB induction blocks euchromatin formation, characterized by histone H3K56 acetylation, leading to a failure in gametic nuclei production. We propose that PM-DSBs are responsible for histone replacement during the reprogramming of generative to undifferentiated progeny nuclei.
Medical subject headings
- DNA Breaks, Double-Stranded
- DNA Topoisomerases, Type II
- DNA, Protozoan
- Endodeoxyribonucleases
- Meiosis
- Tetrahymena thermophila