Oskar Fdez-Capetillo

• Bombero torero
• Spanish National Cancer Research Centre

Senescent cells play a causative role in many diseases, and their elimination is a promising therapeutic strategy. Here, through a genome-wide CRISPR/Cas9 screen, we identify the gene PPIF, encoding the mitochondrial protein cyclophilin D (CypD), as a novel senolytic target. Cyclophilin D promotes the transient opening of the mitochondrial permeabi...

SETD8 is a methyltransferase that is overexpressed in several cancers, which monomethylates H4K20 as well as other non-histone targets such as PCNA or p53. We here report novel SETD8 inhibitors, which were discovered while trying to identify chemicals that prevent 53BP1 foci formation, an event mediated by H4K20 methylation. Consistent with previou...

Several viruses hijack various forms of endocytosis in order to infect host cells. Here, we report the discovery of a molecule with antiviral properties that we named virapinib, which limits viral entry by macropinocytosis. The identification of virapinib derives from a chemical screen using high-throughput microscopy, where we identified chemical...

SETD8 is a methyltransferase that is overexpressed in several cancers, which monomethylates H4K20 as well as other non-histone targets such as PCNA or p53. We here report novel SETD8 inhibitors, which were discovered while trying to identify chemicals that prevent 53BP1 foci formation, an event mediated by H4K20 methylation. Consistent with previou...

Background PolyQ diseases are autosomal dominant neurodegenerative disorders caused by the expansion of CAG repeats. While of slow progression, these diseases are ultimately fatal and lack effective therapies. Methods A high-throughput chemical screen was conducted to identify drugs that lower the toxicity of a protein containing the first exon of...

[This corrects the article DOI: 10.1371/journal.pone.0005475.].

Several viruses hijack various forms of endocytosis in order to infect host cells. Here, we report the discovery of a new molecule with antiviral properties that we named virapinib, which limits viral entry by macropinocytosis. The identification of virapinib derives from a chemical screen using High-Throughput Microscopy, where we identified new c...

Nucleolar stress (NS) kills cells through p53-dependent and independent manners. To investigate the mechanisms of p53-indendendent toxicity, we here used (PR)n arginine-rich peptides as inducers of NS, which are found in patients of certain neurodegenerative diseases. Although these peptides accumulate at nucleoli and generate NS, how this translat...

Protein methylation is an important modification beyond epigenetics. However, systems analyses of protein methylation lag behind compared to other modifications. Recently, thermal stability analyses have been developed which provide a proxy of a protein functional status. Here, we show that molecular and functional events closely linked to protein...

Drug repurposing is a versatile strategy to improve current therapies. Disulfiram has long been used in the treatment of alcohol dependency and multiple clinical trials to evaluate its clinical value in oncology are ongoing. We have recently reported that the disulfiram metabolite diethyldithiocarbamate, when combined with copper (CuET), targets th...

Antibodies targeting the PD-1 receptor and its ligand PD-L1 have shown impressive responses in some tumors of bad prognosis. We hypothesized that, since immunosuppressive cells might present several immune checkpoints on their surface, the selective elimination of PD-L1 expressing cells could be efficacious in enabling the activation of antitumoral...

The identification of new therapeutic uses for compounds via computational or experimental approaches, which is widely known as drug repurposing, has the potential to develop novel therapies with pre-existing medicines, thereby reducing the time and costs associated with drug development. Today, several data-driven methodologies have been developed...

Speed is key during infectious disease outbreaks. It is essential, for example, to identify critical host binding factors to pathogens as fast as possible. The complexity of host plasma membrane is often a limiting factor hindering fast and accurate determination of host binding factors as well as high-throughput screening for neutralizing antimicr...

PolyQ diseases are autosomal dominant neurodegenerative disorders caused by the expansion of CAG repeats. While of slow progression, these diseases are ultimately fatal and lack effective therapies. Here, we present our results from a High-Throughput chemical screen oriented to find drugs that lower the toxicity of a protein containing the first ex...

The presentation of neoantigens by HLA-I is essential for the recognition of tumor cells by cytotoxic T cells. Transcriptionally, HLA-I expression is regulated by interferon-dependent activation of JAK/STAT signaling. Accordingly, mutations that inactivate this pathway are one of the main causes of resistance to cancer immunotherapies. Recent evide...

Speed is key during infectious disease outbreaks. It is essential, for example, to identify critical host binding factors to the pathogens as fast as possible. The complexity of host plasma membrane is often a limiting factor hindering fast and accurate determination of host binding factors as well as high-throughput screening for neutralizing anti...

The nucleolus is the site of ribosome biogenesis, one of the most resource-intensive processes in eukaryotic cells. Accordingly, nucleolar morphology and activity are highly responsive to growth signaling and nucleolar insults which are collectively included in the actively evolving concept of nucleolar stress. Importantly, nucleolar alterations ar...

Huntington’s disease (HD) is acknowledged as a fatal autosomal dominant neurodegenerative disorder characterized by progressive neuronal cell death. The causative mechanism of HD remains largely unknown, thereby impedes drug development that has been hampered by a large amount of necessary resources and have found mostly negative results. Thus, it...

The tetracycline repressor (tetR)‐regulated system is a widely used tool to specifically control gene expression in mammalian cells. Based on this system, we generated a human osteosarcoma cell line which allows for inducible expression of an EGFP‐fusion of the TAR DNA‐binding protein 43 (TDP‐43), which has been linked to neurodegenerative diseases...

Amyotrophic lateral sclerosis (ALS) is a deadly neurodegenerative disease with no cure, characterized by the progressive death of motor neurons and subsequent paralysis. Although the last three decades of research have unearthed a growing number of causative mutations, the mechanism driving motor neuron death remains elusive. This article gives an...

Antibodies targeting the PD-1 receptor and its ligand PD-L1 have shown impressive responses in some tumors of bad prognosis. We hypothesized that the selective elimination of PD-L1 expressing cells could similarly have antitumoral effects. To address this question, we developed an inducible suicidal knock-in mouse allele of Pd-l1 (PD-L1ATTAC) which...

FBXW7 is one of the most frequently mutated tumor suppressors, deficiency of which has been associated with resistance to some anticancer therapies. Through bioinformatics and genome-wide CRISPR screens, we here reveal that FBXW7 deficiency leads to multidrug resistance (MDR). Proteomic analyses found an upregulation of mitochondrial factors as a h...

The tetracycline repressor (tetR)-regulated system is a widely used tool to specifically control gene expression in mammalian cells. Based on this system, we generated a human osteosarcoma cell line which allows for inducible expression of an EGFP-fusion of the TAR DNA-binding protein 43 (TDP-43), which has been linked to neurodegenerative diseases...

The ongoing COVID-19 pandemic is one of the biggest health challenges of recent decades. Among the causes of mortality triggered by SARS-CoV-2 infection, the development of an inflammatory “cytokine storm” (CS) plays a determinant role. Here, we used transcriptomic data from the bronchoalveolar lavage fluid (BALF) of COVID-19 patients undergoing a...

FBXW7 is one of the most frequently mutated tumor suppressors, the deficiency of which has been associated with resistance to some anticancer therapies. Through bioinformatic analyses and genome-wide CRISPR screens, we here reveal that FBXW7 deficiency leads to multidrug resistance (MDR), to a bigger extent than well-established MDR-drivers such as...

Antibodies binding to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike have therapeutic promise, but emerging variants show the potential for virus escape. This emphasizes the need for therapeutic molecules with distinct and novel neutralization mechanisms. Here we describe the isolation of a nanobody that interacts simultaneo...

The AAA+ ATPase VCP regulates the extraction of SUMO and ubiquitin-modified DNA replication factors from chromatin. We have previously described that active DNA synthesis is associated with a SUMO-high/ubiquitin-low environment governed by the deubiquitylase USP7. Here, we unveil a functional cooperation between USP7 and VCP in DNA replication, whi...

Among others, expression levels of programmed cell death 1 ligand 1 (PD‐L1) have been explored as biomarkers of the response to immune checkpoint inhibitors in cancer therapy. Here, we present the results of a chemical screen that interrogated how medically approved drugs influence PD‐L1 expression. As expected, corticosteroids and inhibitors of Ja...

Post-translational modification of the DNA replication machinery by ubiquitin and SUMO plays key roles in the faithful duplication of the genetic information. Among other functions, ubiquitination and SUMOylation serve as signals for the extraction of factors from chromatin by the AAA ATPase VCP. In addition to the regulation of DNA replication ini...

Dysregulation of the c-Myc oncogene occurs in a wide variety of haematologic malignancies and its overexpression has been linked with aggressive tumour progression. Here, we show that Poly (ADP-ribose) polymerase (PARP)-1 and PARP-2 exert opposing influences on progression of c-Myc-driven B-cell lymphomas. PARP-1 and PARP-2 catalyse the synthesis a...

We here conducted an image-based chemical screen to evaluate how medically approved drugs, as well as drugs that are currently under development, influence overall translation levels. None of the compounds up-regulated translation, which could be due to the screen being performed in cancer cells grown in full media where translation is already pres...

Due to their capability to transport chemicals or proteins into target cells, cell-penetrating peptides (CPPs) are being developed as therapy delivery tools. However, and despite their interesting properties, arginine-rich CPPs often show toxicity for reasons that remain poorly understood. Using a (PR)n dipeptide repeat that has been linked to amyo...

Chemical inhibitors of the deubiquitinase USP7 are currently being developed as anticancer agents based on their capacity to stabilize P53. Regardless of this activity, USP7 inhibitors also generate DNA damage in a p53-independent manner. However, the mechanism of this genotoxicity and its contribution to the anticancer effects of USP7 inhibitors a...

The ongoing COVID-19 pandemic is one of the biggest health and societal challenges of the recent decades. Among the causes of mortality triggered by SARS-CoV-2 infection, the presence of an inflammatory "cytokine storm" (CS) at later stages of the disease has been found to play a determinant role. Here, we used available transcriptomic data from th...

mRNA translation is one of the most energy-demanding processes for living cells, alterations of which have been frequently documented in human disease. Using recently developed technologies that enable image-based quantitation of overall translation levels, we here conducted a chemical screen to evaluate how medically approved drugs, as well as dru...

Replication Stress (RS) is a type of DNA damage generated at the replication fork, characterized by single-stranded DNA (ssDNA) accumulation, and which can be caused by a variety of factors. Previous studies have reported elevated RS levels in aged cells. In addition, mouse models with a deficient RS response show accelerated aging. However, the re...

Unrepaired DNA damage during embryonic development can be potentially inherited by a large population of cells. However, the quality control mechanisms that minimize the contribution of damaged cells to developing embryos remain poorly understood. Here, we uncovered an ATR- and CHK1-mediated transcriptional response to replication stress (RS) in mo...

Replication Stress (RS) is a type of DNA damage generated at the replication fork, characterized by single-stranded DNA (ssDNA) accumulation, and which can be caused by a variety of factors. Previous studies have reported elevated RS levels in aged cells. In addition, mouse models with a deficient RS response show accelerated aging. However, the re...

Unrepaired DNA damage during embryonic development can be potentially inherited by a large population of cells. However, the quality control mechanisms that minimize the contribution of damaged cells to developing embryos remain poorly understood. Here, we uncovered an ATR- and CHK1-mediated transcriptional response to replication stress (RS) in ES...

Estrogen receptor (ER)-positive breast tumors are routinely treated with estrogen-depriving therapies. Despite their effectiveness, patients often progress into a more aggressive form of the disease. Through a chemical screen oriented to identify chemicals capable of inducing the expression of the immune-checkpoint ligand PD-L1, we found antiestrog...

The recent availability of somatic haploid cell lines has provided a unique tool for genetic studies in mammals. However, the percentage of haploid cells rapidly decreases in these cell lines, which we recently showed is due to their overgrowth by diploid cells present in the cultures. Based on this property, we have now performed a phenotypic chem...

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The G2/M checkpoint coordinates DNA replication with mitosis and thereby prevents chromosome segregation in the presence of unreplicated or damaged DNA. Here, we show that the RNA-binding protein TIAR is essential for the G2/M checkpoint and that TIAR accumulates in nuclear foci in late G2 and prophase in cells suffering from replication stress. Th...

The expansion of GGGGCC repeats within the first intron of C9ORF72 constitutes the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Through repeat-associated non-ATG translation, these expansions are translated into dipeptide repeats (DPRs), some of which accumulate at nucleoli and lead to cell death. We h...

Expanded intronic GGGGCC sequences in C9ORF72 found in patients of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are translated into several dipeptide-repeat polypeptides (DPRs), from which the two that contain arginine, (PR)n and (GR)n, accumulate at nucleoli and kill cells. While this toxicity plays an important role in AL...

Precise execution of recombination during meiosis is essential for forming chromosomally-balanced gametes. Meiotic recombination initiates with the formation and resection of DNA double-strand breaks (DSBs). Cellular responses to meiotic DSBs are critical for efficient repair and quality control, but molecular features of these remain poorly unders...

The chemical treatment of cancer started with the realization that DNA damaging agents such as mustard gas present notable antitumoural properties. Consequently, early drug development focused on genotoxic chemicals, some of which are still widely used in the clinic. However, the efficacy of such therapies is often limited by the side effects of th...

DNA replication needs to be carefully controlled to prevent genomic instability and ensure cellular fitness. ATR is a PI3K-like kinase and is a central factor supervising the correct completion of DNA replication. The recruitment, activation and specific substrate recognition of ATR is tightly regulated to promote differential responses at a local...

To ensure a faithful segregation of chromosomes, DNA must be fully replicated before mitotic entry. However, how cells sense the completion of DNA replication and to what extent this is linked to the activation of the mitotic machinery remains poorly understood. We previously showed that USP7 is a replisome-associated deubiquitinase with an essenti...

The RNA polymerase II-associated protein 1 (RPAP1) is conserved across metazoa and required for stem cell differentiation in plants; however, very little is known about its mechanism of action or its role in mammalian cells. Here, we report that RPAP1 is essential for the expression of cell identity genes and for cell viability. Depletion of RPAP1...

Table S3. RNA-Seq Data Summary in MEFs at Day 3 after shSCR or shRPAP1, with Network Analysis, Related to Figure 2 Sheets 1-4: List of all normalized mRNA expression data generated by RNA-seq in MEF cells at day 3 after lentiviral transduction with non-targeting control (shSCR) or with RPAP1 targeting (shRPAP1) shRNAs. Genes are ranked from most u...

Table S1. RNA-Seq Data Summary in ESCs + 24 hr Differentiation, Related to Figure 2 Sheets 1-3: List of all normalized mRNA expression data generated by RNA-seq in mouse ES cells after lentiviral transduction with non-targeting control (shSCR) or with RPAP1 targeting (shRPAP1) shRNAs, followed by 24 hr of differentiation by LIF-removal. Genes are...

Table S4. Mass Spectrometry Proteomic Analyses of RNA Pol II Interactome in MEFs at Day 2 after RPAP1 Depletion, Related to Figure 4 Sheet 1: Summary of RNA Pol II interactome in MEFs at day 2 in control (shSCR) or after RPAP1 depletion (shRPAP1). Sheet 2: Magnified image of Figure 4D, showing the RNA Pol II interactome identified in this study. S...

Table S2. GSEA Functional Analyses of mRNA Expression and ChIP-Seq Data, Related to Figures 2 and 5 Sheets 1-3: GSEA results. Sheets 4-7: Processing of Arabidopsis RPAP1-mutation data (Sanmartín et al., 2011) to the nearest mouse homolog for use as a ranked list in GSEA analysis (see also: Supplemental Experimental Procedures). In sheets 1-3, the...

Table S5. Pol II Quantification, Calculations, and GSEA Analyses on ChIP-Seq Data in this Study, Related to Figure 5 Sheets 1-8: Summary tables of RNA Pol II quantification, calculations, and GSEA analyses on ChIP-seq data in this study, related to Figures 5 and S5. See also Supplemental Experimental Procedures in section describing the ChIP-seq d...

Significance Haploidy is a critical advantage for studies on gene function, because only one allele needs to be mutated to yield a phenotype. That is why yeast has led genetic screenings in recent decades. All mammalian cells except germ cells contain two or more sets of chromosomes. Recently, several mammalian haploid cell lines have been obtained...

The development of haploid mammalian cell lines, coupled to next generation sequencing, has recently facilitated forward genetic screenings in mammals. For mutagenesis, retrovirus- or transposon-based genetraps are frequently used. Current methods to map genetrap insertions are based on inverse- or splinkerette-PCR, which despite their efficacy are...

Precise execution of recombination during meiosis is essential for forming chromosomally balanced gametes. Meiotic recombination initiates with the formation and resection of DNA double-strand breaks (DSBs). Binding of replication protein A (RPA) at resected DSBs fosters association of RAD51 and DMC1, the primary effectors of homology search. It is...

Brca1- and Brca2-deficient cells have reduced capacity to repair DNA double strand breaks (DSBs) by homologous recombination (HR) and consequently are hypersensitive to DNA damaging agents including cisplatin and poly(ADP-ribose) polymerase (PARP) inhibitors. Here we show that loss of the MLL3/4 complex protein PTIP protects Brca1/2-deficient cells...

s: AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; November 2-5, 2016; Montreal, QC, Canada Mouse embryonic stem cells (mESCs) represent an excellent platform to study processes of developmental biology, model disease in vitro and in vivo or perform drug discoveries. In the last few years, the development of prec...

It has come to our attention that in this Article, owing to an error during the production process, 'Brca2' was mislabelled as 'Brca1' in Fig. 4b, and 'Parp1' was mislabelled as 'Ptip' in Fig. 4e. These errors have been corrected in the online versions of the paper. © 2016 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

Among the various subtypes of acute myeloid leukemia (AML), those with chromosomal rearrangements of the MLL oncogene (AML-MLL) have a poor prognosis. AML-MLL tumor cells are resistant to current genotoxic therapies because of an attenuated response by p53, a protein that induces cell cycle arrest and apoptosis in response to DNA damage. In additio...

Post-translational modifications regulate each step of DNA replication to ensure the faithful transmission of genetic information. In this context, we recently showed that deubiquitination of SUMO2/3 and SUMOylated proteins by USP7 helps to create a SUMO-rich and ubiquitin-low environment around replisomes that is necessary to maintain the activity...

The Pold3 gene encodes a subunit of the Polδ DNA polymerase complex. Pold3 orthologs are not essential in Saccharomyces cerevisiae or chicken DT40 cells, but the Schizosaccharomyces pombe ortholog is essential. POLD3 also has a specialized role in the repair of broken replication forks, suggesting that POLD3 activity could be particularly relevant...

Cells deficient in the Brca1 and Brca2 genes have reduced capacity to repair DNA double-strand breaks by homologous recombination and consequently are hypersensitive to DNA-damaging agents, including cisplatin and poly(ADP-ribose) polymerase (PARP) inhibitors. Here we show that loss of the MLL3/4 complex protein, PTIP, protects Brca1/2-deficient ce...

One recurring theme in drug development is to exploit synthetic lethal properties as means to preferentially damage the DNA of cancer cells. We and others have previously developed inhibitors of the ATR kinase, shown to be particularly genotoxic for cells expressing certain oncogenes. In contrast, the mechanisms of resistance to ATR inhibitors rema...

Post-translational modification of proteins by ubiquitin (Ub) and Ub-like modifiers regulates DNA replication. We have previously shown that chromatin around replisomes is rich in SUMO and poor in Ub, whereas mature chromatin exhibits an opposite pattern. How this SUMO-rich, Ub-poor environment is maintained at sites of DNA replication in mammalian...

Replicative stress during embryonic development influences ageing and predisposition to disease in adults. A protective mechanism against replicative stress is provided by the licensing of thousands of origins in G1 that are not necessarily activated in the subsequent S-phase. These 'dormant' origins provide a backup in the presence of stalled fork...

The generation of induced pluripotent stem cells (iPSC) from adult somatic cells is one of the most remarkable discoveries in recent decades. However, several works have reported evidence of genomic instability in iPSC, raising concerns on their biomedical use. The reasons behind the genomic instability observed in iPSC remain mostly unknown. Here...

The ribonucleotide reductase (RNR) complex, composed of a catalytic subunit (RRM1) and a regulatory subunit (RRM2), is thought to be a rate-limiting enzymatic complex for the production of nucleotides. In humans, the Rrm1 gene lies at 11p15.5, a tumor suppressor region, and RRM1 expression in cancer has been shown to predict responses to chemothera...

In Saccharomyces cerevisiae, absence of the checkpoint kinase Mec1 (ATR) is viable upon mutations that increase the activity of the ribonucleotide reductase (RNR) complex. Whether this pathway is conserved in mammals remains unknown. Here we show that cells from mice carrying extra alleles of the RNR regulatory subunit RRM2 (Rrm2TG) present supraph...

Damaged DNA has a profound impact on mammalian health and overall survival. In addition to being the source of mutations that initiate cancer, the accumulation of toxic amounts of DNA damage can cause severe developmental diseases and accelerate aging. Therefore, understanding how cells respond to DNA damage has become one of the most intense areas...

Ewing sarcomas (ES) are pediatric bone tumors that arise from a driver translocation, most frequently EWS/FLI1. Current ES treatment involves DNA damaging agents, yet the basis for the sensitivity to these therapies remains unknown. Oncogene-induced replication stress (RS) is a known source of endogenous DNA damage in cancer, which is suppressed by...

Problems arising during DNA replication require the activation of the ATR–CHK1 pathway to ensure the stabilization and repair of the forks, and to prevent the entry into mitosis with unreplicated genomes. Whereas the pathway is essential at the cellular level, limiting its activity is particularly detrimental for some cancer cells. Here we review t...

Fanconi anemia is characterized by a higher sensitivity to DNA crosslinking agents, including aldehydes. In this issue of Molecular Cell, Oberbeck et al. (2014) reveal that detoxification of aldehydes by pregnant mothers contributes to limit the severity of the disease.

Genotoxic chemotherapy is the most common cancer treatment strategy. However, its untargeted generic DNA-damaging nature and associated systemic cytotoxicity greatly limit its therapeutic applications. Here, we used a haploid genetic screen in human cells to discover an absolute dependency of the clinically evaluated anticancer compound YM155 on so...

Stable Fos expression in the osteoblast lineage results in the development of osteosarcomas (OS) in mice, yet the underlying mechanisms are poorly understood. Using a genetic system in which Fos expression can be induced in osteoblasts in a Doxycycline-dependent manner and through subsequent RNA sequencing and gene set enrichment analysis, we were...

The Anaphase-promoting complex/cyclosome (APC/C) cofactor Cdh1 modulates cell proliferation by targeting multiple cell-cycle regulators for ubiquitin-dependent degradation. Lack of Cdh1 results in structural and numerical chromosome aberrations, a hallmark of genomic instability. By using a proteomic approach in Cdh1-null cells and mouse tissues, w...

The DNA Damage response is a crucial signaling network that preserves the integrity of the genome. This network is an ensemble of distinct but often overlapping sub-networks, where different components fulfill distinct functions in precise spatial and temporal scenarios. To understand how these elements have been assembled together in humans, we pe...