Phosphoribosyl modification of poly-ubiquitin chains at the Legionella-containing vacuole prohibiting autophagy adaptor recognition.

Ubiquitination is a posttranslational modification in eukaryotes that plays a significant role in the infection of intracellular microbial pathogens, such as Legionella pneumophila. While the Legionella-containing vacuole (LCV) is coated with ubiquitin (Ub), it avoids recognition by autophagy adaptors. Here, we report that the Sdc and Sde families of effectors work together to build ubiquitinated species around the LCV.

A phosphorylation-controlled switch confers cell cycle-dependent protein relocalization.

Tools for acute manipulation of protein localization enable elucidation of spatiotemporally defined functions, but their reliance on exogenous triggers can interfere with cell physiology. This limitation is particularly apparent for studying mitosis, whose highly choreographed events are sensitive to perturbations. Here we exploit the serendipitous discovery of a phosphorylation-controlled, cell cycle-dependent localization change of the adaptor protein PLEKHA5 to develop a system for mitosis-specific protein recruitment to the plasma membrane that requires no exogenous stimulus.

Profiling Tel1 Signaling Reveals a Non-Canonical Motif Targeting DNA Repair and Telomere Control Machineries.

The stability of the genome relies on Phosphatidyl Inositol 3-Kinase-related Kinases (PIKKs) that sense DNA damage and trigger elaborate downstream signaling responses. In , the Tel1 kinase (ortholog of human ATM) is activated at DNA double strand breaks (DSBs) and short telomeres. Despite the well-established roles of Tel1 in the control of telomere maintenance, suppression of chromosomal rearrangements, activation of cell cycle checkpoints, and repair of DSBs, the substrates through which Tel1 controls these processes remain incompletely understood.

In-depth mapping of DNA-PKcs signaling uncovers noncanonical features of its kinase specificity.

DNA-PKcs is a DNA damage sensor kinase with established roles in DNA double-strand break repair via nonhomologous end joining. Recent studies have revealed additional roles of DNA-PKcs in the regulation of transcription, translation, and DNA replication. However, the substrates through which DNA-PKcs regulates these processes remain largely undefined.

A phosphorylation-controlled switch confers cell cycle-dependent protein relocalization.

Tools for acute manipulation of protein localization enable elucidation of spatiotemporally defined functions, but their reliance on exogenous triggers can interfere with cell physiology. This limitation is particularly apparent for studying mitosis, whose highly choreographed events are sensitive to perturbations. Here we exploit the serendipitous discovery of a phosphorylation-controlled, cell cycle-dependent localization change of the adaptor protein PLEKHA5 to develop a system for mitosis-specific protein recruitment to the plasma membrane that requires no exogenous stimulus.

Multi-step control of homologous recombination via Mec1/ATR suppresses chromosomal rearrangements.

The Mec1/ATR kinase is crucial for genome stability, yet the mechanism by which it prevents gross chromosomal rearrangements (GCRs) remains unknown. Here we find that in cells with deficient Mec1 signaling, GCRs accumulate due to the deregulation of multiple steps in homologous recombination (HR). Mec1 primarily suppresses GCRs through its role in activating the canonical checkpoint kinase Rad53, which ensures the proper control of DNA end resection.

A TOPBP1 allele causing male infertility uncouples XY silencing dynamics from sex body formation.

Meiotic sex chromosome inactivation (MSCI) is a critical feature of meiotic prophase I progression in males. While the ATR kinase and its activator TOPBP1 are key drivers of MSCI within the specialized sex body (SB) domain of the nucleus, how they promote silencing remains unclear given their multifaceted meiotic functions that also include DNA repair, chromosome synapsis, and SB formation. Here we report a novel mutant mouse harboring mutations in the TOPBP1-BRCT5 domain.

The DNA helicase FANCJ (BRIP1) functions in double strand break repair processing, but not crossover formation during prophase I of meiosis in male mice.

Meiotic recombination between homologous chromosomes is initiated by the formation of hundreds of programmed double-strand breaks (DSBs). Approximately 10% of these DSBs result in crossovers (COs), sites of physical DNA exchange between homologs that are critical to correct chromosome segregation. Virtually all COs are formed by coordinated efforts of the MSH4/MSH5 and MLH1/MLH3 heterodimers, the latter representing the defining marks of CO sites.

IN-DEPTH MAPPING OF DNA-PKcs SIGNALING UNCOVERS CONSERVED FEATURES OF ITS KINASE SPECIFICITY.

DNA-PKcs is a DNA damage sensor kinase with established roles in DNA double-strand break repair via non-homologous end joining. Recent studies have revealed additional roles of DNA-PKcs in the regulation of transcription, translation and DNA replication. However, the substrates through which DNA-PKcs regulates these processes remain largely undefined.

Multi-Step Control of Homologous Recombination by Mec1/ATR Ensures Robust Suppression of Gross Chromosomal Rearrangements.

The Mec1/ATR kinase is crucial for genome stability, yet the mechanism by which it prevents gross chromosomal rearrangements (GCRs) remains unknown. Here we find that in cells with deficient Mec1 signaling, GCRs accumulate due to the deregulation of multiple steps in homologous recombination (HR). Mec1 primarily suppresses GCRs through its role in activating the canonical checkpoint kinase Rad53, which ensures the proper control of DNA end resection.

Proteomic analysis of exosomes secreted during the epithelial-mesenchymal transition and potential biomarkers of mesenchymal high-grade serous ovarian carcinoma.

Background: The epithelial-mesenchymal transition (EMT) promotes cell signaling and morphology alterations, contributing to cancer progression. Exosomes, extracellular vesicles containing proteins involved in cell-cell communication, have emerged as a potential source of biomarkers for several diseases.

Methods: Our aim was to assess the proteome content of exosomes secreted after EMT-induction to identify potential biomarkers for ovarian cancer classification.

The DNA helicase FANCJ (BRIP1) functions in Double Strand Break repair processing, but not crossover formation during Prophase I of meiosis in male mice.

During meiotic prophase I, recombination between homologous parental chromosomes is initiated by the formation of hundreds of programmed double-strand breaks (DSBs), each of which must be repaired with absolute fidelity to ensure genome stability of the germline. One outcome of these DSB events is the formation of Crossovers (COs), the sites of physical DNA exchange between homologs that are critical to ensure the correct segregation of parental chromosomes. However, COs account for only a small (~10%) proportion of all DSB repair events; the remaining 90% are repaired as non-crossovers (NCOs), most by synthesis dependent strand annealing.

ATR takes a crack at the nuclear envelope.

In this issue, Joo et al. and Kovacs et al. report that the ATR kinase promotes nuclear envelope rupture through the phosphorylation of Lamin A/C, inducing processes such as cGAS-STING pathway activation, micronuclei clearance, and potentially cell death.

Phosphoribosyl modification of poly-ubiquitin chains at the -containing vacuole prohibiting autophagy adaptor recognition.

Ubiquitination is a crucial posttranslational modification in eukaryotes that plays a significant role in the infection of intracellular microbial pathogens, such as the bacterium responsible for Legionnaires' disease. While the -containing vacuole (LCV) is coated with ubiquitin (Ub), it avoids recognition by autophagy adaptors. In this study, we report that the Sdc and Sde families of effectors work together to build ubiquitinated species around the LCV.

A TOPBP1 Allele Causing Male Infertility Uncouples XY Silencing Dynamics From Sex Body Formation.

Meiotic sex chromosome inactivation (MSCI) is a critical feature of meiotic prophase I progression in males. While the ATR kinase and its activator TOPBP1 are key drivers of MSCI within the specialized sex body (SB) domain of the nucleus, how they promote silencing remains unclear given their multifaceted meiotic functions that also include DNA repair, chromosome synapsis and SB formation. Here we report a novel mutant mouse harboring mutations in the TOPBP1-BRCT5 domain.

Mec1-independent activation of the Rad53 checkpoint kinase revealed by quantitative analysis of protein localization dynamics.

The replication checkpoint is essential for accurate DNA replication and repair, and maintenance of genomic integrity when a cell is challenged with genotoxic stress. Several studies have defined the complement of proteins that change subcellular location in the budding yeast following chemically induced DNA replication stress using methyl methanesulfonate (MMS) or hydroxyurea (HU). How these protein movements are regulated remains largely unexplored.

Progranulin inhibits phospholipase sPLA2-IIA to control neuroinflammation.

Mutations in the granulin () gene, resulting in haploinsufficiency of the progranulin (PGRN) protein, are a leading cause of frontotemporal lobar degeneration (FTLD) and PGRN polymorphisms are associated with Alzheimer's disease (AD) and Parkinson's disease (PD). PGRN is a key regulator of microglia-mediated inflammation but the mechanism is still unknown. Here we report that PGRN interacts with sPLA2-IIA, a secreted phospholipase involved in inflammatory responses, to downregulate sPLA2-IIA activities and levels.

DNA-PKcs promotes fork reversal and chemoresistance.

The DNA-PKcs kinase mediates the repair of DNA double-strand breaks via classical non-homologous end joining (NHEJ). DNA-PKcs is also recruited to active replication forks, although a role for DNA-PKcs in the control of fork dynamics is unclear. Here, we identify a crucial role for DNA-PKcs in promoting fork reversal, a process that stabilizes stressed replication forks and protects genome integrity.

Proximity Labeling Reveals Spatial Regulation of the Anaphase-Promoting Complex/Cyclosome by a Microtubule Adaptor.

The anaphase-promoting complex/cyclosome (APC/C) coordinates advancement through mitosis via temporally controlled polyubiquitination events. Despite the long-appreciated spatial organization of key events in mitosis mediated largely by cytoskeletal networks, the spatial regulation of APC/C, the major mitotic E3 ligase, is poorly understood. We describe a microtubule-resident protein, PLEKHA5, as an interactor of APC/C and spatial regulator of its activity in mitosis.

A field guide to the proteomics of post-translational modifications in DNA repair.

All cells incur DNA damage from exogenous and endogenous sources and possess pathways to detect and repair DNA damage. Post-translational modifications (PTMs), in the past 20 years, have risen to ineluctable importance in the study of the regulation of DNA repair mechanisms. For example, DNA damage response kinases are critical in both the initial sensing of DNA damage as well as in orchestrating downstream activities of DNA repair factors.

Comprehensive analysis of DNA replication timing across 184 cell lines suggests a role for MCM10 in replication timing regulation.

Cellular proliferation depends on the accurate and timely replication of the genome. Several genetic diseases are caused by mutations in key DNA replication genes; however, it remains unclear whether these genes influence the normal program of DNA replication timing. Similarly, the factors that regulate DNA replication dynamics are poorly understood.

Phosphoproteomics of ATR signaling in mouse testes.

The phosphatidylinositol 3' kinase (PI3K)-related kinase ATR is crucial for mammalian meiosis. ATR promotes meiotic progression by coordinating key events in DNA repair, meiotic sex chromosome inactivation (MSCI), and checkpoint-dependent quality control during meiotic prophase I. Despite its central roles in meiosis, the ATR-dependent meiotic signaling network remains largely unknown.