The formation of programmed DNA double-strand breaks (DSBs) at the beginning of meiotic prophase marks the initiation of meiotic recombination. Meiotic DSB formation is catalyzed by SPO11 and their repair takes place on meiotic chromosome axes. The evolutionarily conserved MEI4 protein is required for meiotic DSB formation and is localized on chromosome axes. Here, we show that HORMAD1, one of the meiotic chromosome axis components, is required for MEI4 localization. Importantly, the quantitative correlation between the level of axis-associated MEI4 and DSB formation suggests that axis-associated MEI4 could be a limiting factor for DSB formation. We also show that MEI1, REC8 and RAD21L are important for proper MEI4 localization. These findings on MEI4 dynamics during meiotic prophase suggest that the association of MEI4 to chromosome axes is required for DSB formation, and that the loss of this association upon DSB repair could contribute to turning off meiotic DSB formation.
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http://dx.doi.org/10.1242/jcs.165464 | DOI Listing |
Nucleic Acids Res
January 2025
Laboratory of Genome Regeneration, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan.
DNA copy number changes via chromosomal rearrangements or the production of extrachromosomal circular DNA. Here, we demonstrate that the histone deacetylase Sir2 maintains the copy number of budding yeast ribosomal RNA gene [ribosomal DNA (rDNA)] by suppressing end resection of DNA double-strand breaks (DSBs) formed upon DNA replication fork arrest in the rDNA and their subsequent homologous recombination (HR)-mediated rDNA copy number changes during DSB repair. Sir2 represses transcription from the regulatory promoter E-pro located near the fork arresting site.
View Article and Find Full Text PDFCell Mol Life Sci
January 2025
Department of Clinical Laboratory, Harbin Medical University Cancer Hospital, 150 Haping Road, Harbin, 150081, China.
Non-small cell lung cancer (NSCLC) has emerged as one of the most prevalent malignancies worldwide. N6-methyladenosine (mA) methylation, a pervasive epigenetic modification in long noncoding RNAs (lncRNAs), plays a crucial role in NSCLC progression. Here, we report that mA modification and the expression of the lncRNA stem cell inhibitory RNA transcript (SCIRT) was significantly upregulated in NSCLC tissues and cells.
View Article and Find Full Text PDFDNA double strand breaks (DSBs) are widely considered the most cytotoxic DNA lesions occurring in cells because they physically disrupt the connectivity of the DNA double helix. Homologous recombination (HR) is a high-fidelity DSB repair pathway that copies the sequence spanning the DNA break from a homologous template, most commonly the sister chromatid. How both DNA ends, and the sister chromatid are held in close proximity during HR is unknown.
View Article and Find Full Text PDFJ Clin Immunol
January 2025
Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children´s Medical Center, Tehran University of Medical Sciences, 62 Qarib St., Keshavarz Blvd, Tehran, 14194, Iran.
Background: Ataxia telangiectasia mutated (ATM) kinase plays a critical role in DNA double-strand break (DSB) repair. Ataxia telangiectasia (A-T) patients exhibit abnormalities in immunoglobulin isotype expression and class switch recombination (CSR). This study investigates the role of residual ATM kinase expression and activity in the severity of A-T disease.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Immunology and Microbiology, Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong 510000, China.
The LIM-domain-only protein LMO2 interacts with LDB1 in context-dependent multiprotein complexes and plays key roles in erythropoiesis and T cell leukemogenesis, but whether they have any roles in B cells is unclear. Through a CRISPR/Cas9-based loss-of-function screening, we identified LMO2 and LDB1 as factors for class switch recombination (CSR) in murine B cells. LMO2 contributes to CSR at least in part by promoting end joining of DNA double-strand breaks (DSBs) and inhibiting end resection.
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