Exportin-mediated nucleocytoplasmic transport maintains Pch2 homeostasis during meiosis.

The meiotic recombination checkpoint reinforces the order of events during meiotic prophase I, ensuring the accurate distribution of chromosomes to the gametes. The AAA+ ATPase Pch2 remodels the Hop1 axial protein enabling adequate levels of Hop1-T318 phosphorylation to support the ensuing checkpoint response. While these events are localized at chromosome axes, the checkpoint activating function of Pch2 relies on its cytoplasmic population. In contrast, forced nuclear accumulation of Pch2 leads to checkpoint inactivation. Here, we reveal the mechanism by which Pch2 travels from the cell nucleus to the cytoplasm to maintain Pch2 cellular homeostasis. Leptomycin B treatment provokes the nuclear accumulation of Pch2, indicating that its nucleocytoplasmic transport is mediated by the Crm1 exportin recognizing proteins containing Nuclear Export Signals (NESs). Consistently, leptomycin B leads to checkpoint inactivation and impaired Hop1 axial localization. Pch2 nucleocytoplasmic traffic is independent of its association with Zip1 and Orc1. We also identify a functional NES in the non-catalytic N-terminal domain of Pch2 that is required for its nucleocytoplasmic trafficking and proper checkpoint activity. In sum, we unveil another layer of control of Pch2 function during meiosis involving nuclear export via the exportin pathway that is crucial to maintain the critical balance of Pch2 distribution among different cellular compartments.

Chromosomal synapsis defects can trigger oocyte apoptosis without elevating numbers of persistent DNA breaks above wild-type levels.

Generation of haploid gametes depends on a modified version of homologous recombination in meiosis. Meiotic recombination is initiated by single-stranded DNA (ssDNA) ends originating from programmed DNA double-stranded breaks (DSBs) that are generated by the topoisomerase-related SPO11 enzyme. Meiotic recombination involves chromosomal synapsis, which enhances recombination-mediated DSB repair, and thus, crucially contributes to genome maintenance in meiocytes. Synapsis defects induce oocyte apoptosis ostensibly due to unrepaired DSBs that persist in asynaptic chromosomes. In mice, SPO11-deficient oocytes feature asynapsis, apoptosis and, surprisingly, numerous foci of the ssDNA-binding recombinase RAD51, indicative of DSBs of unknown origin. Hence, asynapsis is suggested to trigger apoptosis due to inefficient DSB repair even in mutants that lack programmed DSBs. By directly detecting ssDNAs, we discovered that RAD51 is an unreliable marker for DSBs in oocytes. Further, SPO11-deficient oocytes have fewer persistent ssDNAs than wild-type oocytes. These observations suggest that oocyte quality is safeguarded in mammals by a synapsis surveillance mechanism that can operate without persistent ssDNAs.

The N-Terminal Region of the Polo Kinase Cdc5 Is Required for Downregulation of the Meiotic Recombination Checkpoint.

During meiosis, the budding yeast polo-like kinase Cdc5 is a crucial driver of the prophase I to meiosis I (G2/M) transition. The meiotic recombination checkpoint restrains cell cycle progression in response to defective recombination to ensure proper distribution of intact chromosomes to the gametes. This checkpoint detects unrepaired DSBs and initiates a signaling cascade that ultimately inhibits Ndt80, a transcription factor required for CDC5 gene expression. Previous work revealed that overexpression of CDC5 partially alleviates the checkpoint-imposed meiotic delay in the synaptonemal complex-defective zip1Δ mutant. Here, we show that overproduction of a Cdc5 version (Cdc5-ΔN70), lacking the N-terminal region required for targeted degradation of the protein by the APC/C complex, fails to relieve the zip1Δ-induced meiotic delay, despite being more stable and reaching increased protein levels. However, precise mutation of the consensus motifs for APC/C recognition (D-boxes and KEN) has no effect on Cdc5 stability or function during meiosis. Compared to the zip1Δ single mutant, the zip1Δ cdc5-ΔN70 double mutant exhibits an exacerbated meiotic block and reduced levels of Ndt80 consistent with persistent checkpoint activity. Finally, using a CDC5-inducible system, we demonstrate that the N-terminal region of Cdc5 is essential for its checkpoint erasing function. Thus, our results unveil an additional layer of regulation of polo-like kinase function in meiotic cell cycle control.

The Cdc14 Phosphatase Controls Resolution of Recombination Intermediates and Crossover Formation during Meiosis.

Meiotic defects derived from incorrect DNA repair during gametogenesis can lead to mutations, aneuploidies and infertility. The coordinated resolution of meiotic recombination intermediates is required for crossover formation, ultimately necessary for the accurate completion of both rounds of chromosome segregation. Numerous master kinases orchestrate the correct assembly and activity of the repair machinery. Although much less is known, the reversal of phosphorylation events in meiosis must also be key to coordinate the timing and functionality of repair enzymes. Cdc14 is a crucial phosphatase required for the dephosphorylation of multiple CDK1 targets in many eukaryotes. Mutations that inactivate this phosphatase lead to meiotic failure, but until now it was unknown if Cdc14 plays a direct role in meiotic recombination. Here, we show that the elimination of Cdc14 leads to severe defects in the processing and resolution of recombination intermediates, causing a drastic depletion in crossovers when other repair pathways are compromised. We also show that Cdc14 is required for the correct activity and localization of the Holliday Junction resolvase Yen1/GEN1. We reveal that Cdc14 regulates Yen1 activity from meiosis I onwards, and this function is essential for crossover resolution in the absence of other repair pathways. We also demonstrate that Cdc14 and Yen1 are required to safeguard sister chromatid segregation during the second meiotic division, a late action that is independent of the earlier role in crossover formation. Thus, this work uncovers previously undescribed functions of the evolutionary conserved Cdc14 phosphatase in the regulation of meiotic recombination.

Pch2 orchestrates the meiotic recombination checkpoint from the cytoplasm.

During meiosis, defects in critical events trigger checkpoint activation and restrict cell cycle progression. The budding yeast Pch2 AAA+ ATPase orchestrates the checkpoint response launched by synapsis deficiency; deletion of PCH2 or mutation of the ATPase catalytic sites suppress the meiotic block of the zip1Δ mutant lacking the central region of the synaptonemal complex. Pch2 action enables adequate levels of phosphorylation of the Hop1 axial component at threonine 318, which in turn promotes activation of the Mek1 effector kinase and the ensuing checkpoint response. In zip1Δ chromosomes, Pch2 is exclusively associated to the rDNA region, but this nucleolar fraction is not required for checkpoint activation, implying that another yet uncharacterized Pch2 population must be responsible for this function. Here, we have artificially redirected Pch2 to different subcellular compartments by adding ectopic Nuclear Export (NES) or Nuclear Localization (NLS) sequences, or by trapping Pch2 in an immobile extranuclear domain, and we have evaluated the effect on Hop1 chromosomal distribution and checkpoint activity. We have also deciphered the spatial and functional impact of Pch2 regulators including Orc1, Dot1 and Nup2. We conclude that the cytoplasmic pool of Pch2 is sufficient to support the meiotic recombination checkpoint involving the subsequent Hop1-Mek1 activation on chromosomes, whereas the nuclear accumulation of Pch2 has pathological consequences. We propose that cytoplasmic Pch2 provokes a conformational change in Hop1 that poises it for its chromosomal incorporation and phosphorylation. Our discoveries shed light into the intricate regulatory network controlling the accurate balance of Pch2 distribution among different cellular compartments, which is essential for proper meiotic outcomes.

SWR1-Independent Association of H2A.Z to the LINC Complex Promotes Meiotic Chromosome Motion.

The H2A.Z histone variant is deposited into the chromatin by the SWR1 complex, affecting multiple aspects of meiosis. We describe here a SWR1-independent localization of H2A.Z at meiotic telomeres and the centrosome. We demonstrate that H2A.Z colocalizes and interacts with Mps3, the SUN component of the linker of nucleoskeleton, and cytoskeleton (LINC) complex that spans the nuclear envelope and links meiotic telomeres to the cytoskeleton, promoting meiotic chromosome movement. H2A.Z also interacts with the meiosis-specific Ndj1 protein that anchors telomeres to the nuclear periphery via Mps3. Telomeric localization of H2A.Z depends on Ndj1 and the N-terminal domain of Mps3. Although telomeric attachment to the nuclear envelope is maintained in the absence of H2A.Z, the distribution of Mps3 is altered. The velocity of chromosome movement during the meiotic prophase is reduced in the htz1Δ mutant lacking H2A.Z, but it is unaffected in swr1Δ cells. We reveal that H2A.Z is an additional LINC-associated factor that contributes to promote telomere-driven chromosome motion critical for error-free gametogenesis.

DOT-1.1-dependent H3K79 methylation promotes normal meiotic progression and meiotic checkpoint function in C. elegans.

Epigenetic modifiers are emerging as important regulators of the genome. However, how they regulate specific processes during meiosis is not well understood. Methylation of H3K79 by the histone methyltransferase Dot1 has been shown to be involved in the maintenance of genomic stability in various organisms. In S. cerevisiae, Dot1 modulates the meiotic checkpoint response triggered by synapsis and/or recombination defects by promoting Hop1-dependent Mek1 activation and Hop1 distribution along unsynapsed meiotic chromosomes, at least in part, by regulating Pch2 localization. However, how this protein regulates meiosis in metazoans is unknown. Here, we describe the effects of H3K79me depletion via analysis of dot-1.1 or zfp-1 mutants during meiosis in Caenorhabditis elegans. We observed decreased fertility and increased embryonic lethality in dot-1.1 mutants suggesting meiotic dysfunction. We show that DOT-1.1 plays a role in the regulation of pairing, synapsis and recombination in the worm. Furthermore, we demonstrate that DOT-1.1 is an important regulator of mechanisms surveilling chromosome synapsis during meiosis. In sum, our results reveal that regulation of H3K79me plays an important role in coordinating events during meiosis in C. elegans.

Resolvases, Dissolvases, and Helicases in Homologous Recombination: Clearing the Road for Chromosome Segregation.

The execution of recombinational pathways during the repair of certain DNA lesions or in the meiotic program is associated to the formation of joint molecules that physically hold chromosomes together. These structures must be disengaged prior to the onset of chromosome segregation. Failure in the resolution of these linkages can lead to chromosome breakage and nondisjunction events that can alter the normal distribution of the genomic material to the progeny. To avoid this situation, cells have developed an arsenal of molecular complexes involving helicases, resolvases, and dissolvases that recognize and eliminate chromosome links. The correct orchestration of these enzymes promotes the timely removal of chromosomal connections ensuring the efficient segregation of the genome during cell division. In this review, we focus on the role of different DNA processing enzymes that collaborate in removing the linkages generated during the activation of the homologous recombination machinery as a consequence of the appearance of DNA breaks during the mitotic and meiotic programs. We will also discuss about the temporal regulation of these factors along the cell cycle, the consequences of their loss of function, and their specific role in the removal of chromosomal links to ensure the accurate segregation of the genomic material during cell division.

Persistent DNA-break potential near telomeres increases initiation of meiotic recombination on short chromosomes.

Faithful meiotic chromosome inheritance and fertility rely on the stimulation of meiotic crossover recombination by potentially genotoxic DNA double-strand breaks (DSBs). To avoid excessive damage, feedback mechanisms down-regulate DSBs, likely in response to initiation of crossover repair. In Saccharomyces cerevisiae, this regulation requires the removal of the conserved DSB-promoting protein Hop1/HORMAD during chromosome synapsis. Here, we identify privileged end-adjacent regions (EARs) spanning roughly 100 kb near all telomeres that escape DSB down-regulation. These regions retain Hop1 and continue to break in pachynema despite normal synaptonemal complex deposition. Differential retention of Hop1 requires the disassemblase Pch2/TRIP13, which preferentially removes Hop1 from telomere-distant sequences, and is modulated by the histone deacetylase Sir2 and the nucleoporin Nup2. Importantly, the uniform size of EARs among chromosomes contributes to disproportionately high DSB and repair signals on short chromosomes in pachynema, suggesting that EARs partially underlie the curiously high recombination rate of short chromosomes.

Characterization of Pch2 localization determinants reveals a nucleolar-independent role in the meiotic recombination checkpoint.

The meiotic recombination checkpoint blocks meiotic cell cycle progression in response to synapsis and/or recombination defects to prevent aberrant chromosome segregation. The evolutionarily conserved budding yeast Pch2TRIP13 AAA+ ATPase participates in this pathway by supporting phosphorylation of the Hop1HORMAD adaptor at T318. In the wild type, Pch2 localizes to synapsed chromosomes and to the unsynapsed rDNA region (nucleolus), excluding Hop1. In contrast, in synaptonemal complex (SC)-defective zip1Δ mutants, which undergo checkpoint activation, Pch2 is detected only on the nucleolus. Alterations in some epigenetic marks that lead to Pch2 dispersion from the nucleolus suppress zip1Δ-induced checkpoint arrest. These observations have led to the notion that Pch2 nucleolar localization could be important for the meiotic recombination checkpoint. Here we investigate how Pch2 chromosomal distribution impacts checkpoint function. We have generated and characterized several mutations that alter Pch2 localization pattern resulting in aberrant Hop1 distribution and compromised meiotic checkpoint response. Besides the AAA+ signature, we have identified a basic motif in the extended N-terminal domain critical for Pch2's checkpoint function and localization. We have also examined the functional relevance of the described Orc1-Pch2 interaction. Both proteins colocalize in the rDNA, and Orc1 depletion during meiotic prophase prevents Pch2 targeting to the rDNA allowing unwanted Hop1 accumulation on this region. However, Pch2 association with SC components remains intact in the absence of Orc1. We finally show that checkpoint activation is not affected by the lack of Orc1 demonstrating that, in contrast to previous hypotheses, nucleolar localization of Pch2 is actually dispensable for the meiotic checkpoint.

The Pch2 AAA+ ATPase promotes phosphorylation of the Hop1 meiotic checkpoint adaptor in response to synaptonemal complex defects.

Meiotic cells possess surveillance mechanisms that monitor critical events such as recombination and chromosome synapsis. Meiotic defects resulting from the absence of the synaptonemal complex component Zip1 activate a meiosis-specific checkpoint network resulting in delayed or arrested meiotic progression. Pch2 is an evolutionarily conserved AAA+ ATPase required for the checkpoint-induced meiotic block in the zip1 mutant, where Pch2 is only detectable at the ribosomal DNA array (nucleolus). We describe here that high levels of the Hop1 protein, a checkpoint adaptor that localizes to chromosome axes, suppress the checkpoint defect of a zip1 pch2 mutant restoring Mek1 activity and meiotic cell cycle delay. We demonstrate that the critical role of Pch2 in this synapsis checkpoint is to sustain Mec1-dependent phosphorylation of Hop1 at threonine 318. We also show that the ATPase activity of Pch2 is essential for its checkpoint function and that ATP binding to Pch2 is required for its localization. Previous work has shown that Pch2 negatively regulates Hop1 chromosome abundance during unchallenged meiosis. Based on our results, we propose that, under checkpoint-inducing conditions, Pch2 also possesses a positive action on Hop1 promoting its phosphorylation and its proper distribution on unsynapsed chromosome axes.

Impact of histone H4K16 acetylation on the meiotic recombination checkpoint in Saccharomyces cerevisiae.

In meiotic cells, the pachytene checkpoint or meiotic recombination checkpoint is a surveillance mechanism that monitors critical processes, such as recombination and chromosome synapsis, which are essential for proper distribution of chromosomes to the meiotic progeny. Failures in these processes lead to the formation of aneuploid gametes. Meiotic recombination occurs in the context of chromatin; in fact, the histone methyltransferase Dot1 and the histone deacetylase Sir2 are known regulators of the pachytene checkpoint in Saccharomyces cerevisiae. We report here that Sas2-mediated acetylation of histone H4 at lysine 16 (H4K16ac), one of the Sir2 targets, modulates meiotic checkpoint activity in response to synaptonemal complex defects. We show that, like sir2, the H4-K16Q mutation, mimicking constitutive acetylation of H4K16, eliminates the delay in meiotic cell cycle progression imposed by the checkpoint in the synapsis-defective zip1 mutant. We also demonstrate that, like in dot1, zip1-induced phosphorylation of the Hop1 checkpoint adaptor at threonine 318 and the ensuing Mek1 activation are impaired in H4-K16 mutants. However, in contrast to sir2 and dot1, the H4-K16R and H4-K16Q mutations have only a minor effect in checkpoint activation and localization of the nucleolar Pch2 checkpoint factor in ndt80-prophase-arrested cells. We also provide evidence for a cross-talk between Dot1-dependent H3K79 methylation and H4K16ac and show that Sir2 excludes H4K16ac from the rDNA region on meiotic chromosomes. Our results reveal that proper levels of H4K16ac orchestrate this meiotic quality control mechanism and that Sir2 impinges on additional targets to fully activate the checkpoint.

Flexibility in crosstalk between H2B ubiquitination and H3 methylation in vivo.

Histone H2B ubiquitination is a dynamic modification that promotes methylation of histone H3K79 and H3K4. This crosstalk is important for the DNA damage response and has been implicated in cancer. Here, we show that in engineered yeast strains, ubiquitins tethered to every nucleosome promote H3K79 and H3K4 methylation from a proximal as well as a more distal site, but only if in a correct orientation. This plasticity indicates that the exact location of the attachment site, the native ubiquitin-lysine linkage and ubiquitination cycles are not critical for trans-histone crosstalk in vivo. The flexibility in crosstalk also indicates that other ubiquitination events may promote H3 methylation.

Dynamics of DOT1L localization and H3K79 methylation during meiotic prophase I in mouse spermatocytes.

During meiotic prophase I, interactions between maternal and paternal chromosomes, under checkpoint surveillance, establish connections between homologs that promote their accurate distribution to meiotic progeny. In human, faulty meiosis causes aneuploidy resulting in miscarriages and genetic diseases. Meiotic processes occur in the context of chromatin; therefore, histone post-translational modifications are expected to play important roles. Here, we report the cytological distribution of the evolutionarily conserved DOT1L methyltransferase and the different H3K79 methylation states resulting from its activity (mono-, di- and tri-methylation; H3K79me1, me2 and me3, respectively) during meiotic prophase I in mouse spermatocytes. In the wild type, whereas low amounts of H3K79me1 are rather uniformly present throughout prophase I, levels of DOT1L, H3K79me2 and H3K79me3 exhibit a notable increase from pachynema onwards, but with differential subnuclear distribution patterns. The heterochromatic centromeric regions and the sex body are enriched for H3K79me3. In contrast, H3K79me2 is present all over the chromatin, but is largely excluded from the sex body despite the accumulation of DOT1L. In meiosis-defective mouse mutants, the increase of DOT1L and H3K79me is blocked at the same stage where meiosis is arrested. H3K79me patterns, combined with the cytological analysis of the H3.3, γH2AX, macroH2A and H2A.Z histone variants, are consistent with a differential role for these epigenetic marks in male mouse meiotic prophase I. We propose that H3K79me2 is related to transcriptional reactivation on autosomes during pachynema, whereas H3K79me3 may contribute to the maintenance of repressive chromatin at centromeric regions and the sex body.

Dot1-dependent histone H3K79 methylation promotes activation of the Mek1 meiotic checkpoint effector kinase by regulating the Hop1 adaptor.

During meiosis, accurate chromosome segregation relies on the proper interaction between homologous chromosomes, including synapsis and recombination. The meiotic recombination checkpoint is a quality control mechanism that monitors those crucial events. In response to defects in synapsis and/or recombination, this checkpoint blocks or delays progression of meiosis, preventing the formation of aberrant gametes. Meiotic recombination occurs in the context of chromatin and histone modifications, which play crucial roles in the maintenance of genomic integrity. Here, we unveil the role of Dot1-dependent histone H3 methylation at lysine 79 (H3K79me) in this meiotic surveillance mechanism. We demonstrate that the meiotic checkpoint function of Dot1 relies on H3K79me because, like the dot1 deletion, H3-K79A or H3-K79R mutations suppress the checkpoint-imposed meiotic delay of a synapsis-defective zip1 mutant. Moreover, by genetically manipulating Dot1 catalytic activity, we find that the status of H3K79me modulates the meiotic checkpoint response. We also define the phosphorylation events involving activation of the meiotic checkpoint effector Mek1 kinase. Dot1 is required for Mek1 autophosphorylation, but not for its Mec1/Tel1-dependent phosphorylation. Dot1-dependent H3K79me also promotes Hop1 activation and its proper distribution along zip1 meiotic chromosomes, at least in part, by regulating Pch2 localization. Furthermore, HOP1 overexpression bypasses the Dot1 requirement for checkpoint activation. We propose that chromatin remodeling resulting from unrepaired meiotic DSBs and/or faulty interhomolog interactions allows Dot1-mediated H3K79-me to exclude Pch2 from the chromosomes, thus driving localization of Hop1 along chromosome axes and enabling Mek1 full activation to trigger downstream responses, such as meiotic arrest.

Reversal of PCNA ubiquitylation by Ubp10 in Saccharomyces cerevisiae.

Regulation of PCNA ubiquitylation plays a key role in the tolerance to DNA damage in eukaryotes. Although the evolutionary conserved mechanism of PCNA ubiquitylation is well understood, the deubiquitylation of ubPCNA remains poorly characterized. Here, we show that the histone H2B(K123) ubiquitin protease Ubp10 also deubiquitylates ubPCNA in Saccharomyces cerevisiae. Our results sustain that Ubp10-dependent deubiquitylation of the sliding clamp PCNA normally takes place during S phase, likely in response to the simple presence of ubPCNA. In agreement with this, we show that Ubp10 forms a complex with PCNA in vivo. Interestingly, we also show that deletion of UBP10 alters in different ways the interaction of PCNA with DNA polymerase ζ-associated protein Rev1 and with accessory subunit Rev7. While deletion of UBP10 enhances PCNA-Rev1 interaction, it decreases significantly Rev7 binding to the sliding clamp. Finally, we report that Ubp10 counteracts Rad18 E3-ubiquitin ligase activity on PCNA at lysine 164 in such a manner that deregulation of Ubp10 expression causes tolerance impairment and MMS hypersensitivity.

The Smc5-Smc6 complex is required to remove chromosome junctions in meiosis.

Meiosis, a specialized cell division with a single cycle of DNA replication round and two consecutive rounds of nuclear segregation, allows for the exchange of genetic material between parental chromosomes and the formation of haploid gametes. The structural maintenance of chromosome (SMC) proteins aid manipulation of chromosome structures inside cells. Eukaryotic SMC complexes include cohesin, condensin and the Smc5-Smc6 complex. Meiotic roles have been discovered for cohesin and condensin. However, although Smc5-Smc6 is known to be required for successful meiotic divisions, the meiotic functions of the complex are not well understood. Here we show that the Smc5-Smc6 complex localizes to specific chromosome regions during meiotic prophase I. We report that meiotic cells lacking Smc5-Smc6 undergo catastrophic meiotic divisions as a consequence of unresolved linkages between chromosomes. Surprisingly, meiotic segregation defects are not rescued by abrogation of Spo11-induced meiotic recombination, indicating that at least some chromosome linkages in smc5-smc6 mutants originate from other cellular processes. These results demonstrate that, as in mitosis, Smc5-Smc6 is required to ensure proper chromosome segregation during meiosis by preventing aberrant recombination intermediates between homologous chromosomes.

The budding yeast polo-like kinase Cdc5 regulates the Ndt80 branch of the meiotic recombination checkpoint pathway.

Defects in chromosome synapsis and/or meiotic recombination activate a surveillance mechanism that blocks meiotic cell cycle progression to prevent anomalous chromosome segregation and formation of aberrant gametes. In the budding yeast zip1 mutant, which lacks a synaptonemal complex component, the meiotic recombination checkpoint is triggered, resulting in extremely delayed meiotic progression. We report that overproduction of the polo-like kinase Cdc5 partially alleviates the meiotic prophase arrest of zip1, leading to the formation of inviable meiotic products. Unlike vegetative cells, we demonstrate that Cdc5 overproduction does not stimulate meiotic checkpoint adaptation because the Mek1 kinase remains activated in zip1 2µ-CDC5 cells. Inappropriate meiotic divisions in zip1 promoted by high levels of active Cdc5 do not result from altered function of the cyclin-dependent kinase (CDK) inhibitor Swe1. In contrast, CDC5 overexpression leads to premature induction of the Ndt80 transcription factor, which drives the expression of genes required for meiotic divisions, including CLB1. We also show that depletion of Cdc5 during meiotic prophase prevents the production of Ndt80 and that CDK activity contributes to the induction of Ndt80 in zip1 cells overexpressing CDC5. Our results reveal a role for Cdc5 in meiotic checkpoint control by regulating Ndt80 function.

The Ddc2/ATRIP checkpoint protein monitors meiotic recombination intermediates.

During meiosis, accurate segregation of intact chromosomes is essential for generating healthy gametes. Defects in recombination and/or chromosome synapsis activate the pachytene checkpoint, which delays meiotic cell cycle progression to avoid aberrant chromosome segregation and formation of defective gametes. Here, we characterize the role of the conserved DNA damage checkpoint protein Ddc2/ATRIP in this meiotic surveillance mechanism. We show that deletion of DDC2 relieves the checkpoint-dependent meiotic block that occurs in Saccharomyces cerevisiae mutants defective in various aspects of meiotic chromosome dynamics and results in the generation of faulty meiotic products. Moreover, production of the Ddc2 protein is induced during meiotic prophase, accumulates in checkpoint-arrested mutants and localizes to distinctive chromosomal foci. Formation of meiotic Ddc2 foci requires the generation of Spo11-dependent DNA double-strand breaks (DSBs), and is impaired in an RPA mutant. Chromatin immunoprecipitation analysis reveals that Ddc2 accumulates at meiotic DSB sites, indicating that Ddc2 senses the presence of meiotic recombination intermediates. Furthermore, pachytene checkpoint signaling is defective in the ddc2 mutant. In addition, we show that mammalian ATRIP colocalizes with ATR, TopBP1 and RPA at unsynapsed regions of mouse meiotic chromosomes. Thus, our results point to an evolutionary conserved role for Ddc2/ATRIP in monitoring meiotic chromosome metabolism.