ATM and PRDM9 regulate SPO11-bound recombination intermediates during meiosis

Area of Science:

• Genetics
• Molecular Biology
• Cell Biology

Background:

• Meiotic recombination initiates with SPO11-induced double-strand breaks (DSBs).
• PRDM9 (methyltransferase) guides SPO11 targeting, and ATM kinase regulates DSB numbers in mammals.
• DSB repair involves MRE11 nuclease, DMC1 filament loading, and homolog invasion.

Purpose of the Study:

• To directly detect meiotic DSBs and resection using END-seq in mouse spermatocytes.
• To investigate the roles of DMC1, 53BP1, BRCA1, and EXO1 in DSB resection.
• To identify SPO11-bound intermediates and understand PRDM9 and ATM's regulation of SPO11 processing.

Main Methods:

• Employing END-seq on mouse spermatocytes with low sample input.
• Utilizing enzymatic modifications to END-seq for detecting SPO11-bound intermediates.
• Analyzing spermatocytes from wild-type and Atm-deficient mice.

Main Results:

• DMC1 was found to limit both minimum and maximum DNA resection lengths.
• 53BP1, BRCA1, and EXO1 showed minimal roles in the observed resection.
• A SPO11-bound meiotic recombination intermediate (SPO11-RI) was detected at all hotspots.
• PRDM9's chromatin binding was proposed to asymmetrically block MRE11 release of SPO11.
• Defective MRE11-initiated resection in Atm-/- spermatocytes led to trapped SPO11 cleavage complexes.

Conclusions:

• ATM and PRDM9 are critical local regulators of mammalian SPO11 processing, beyond governing initial DSB formation.
• DMC1 plays a key role in controlling the extent of DNA resection during meiotic recombination.
• END-seq is a powerful tool for studying meiotic DSB dynamics with low sample input.