Artículos (Genética)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10879

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Provision of preferred nutrients to macrophages promotes Salmonella intracellular replication without relying on Type III secretion systems
(Public Library of Science, 2026-07-09) García Rodríguez, Francisco Javier; Martínez Oca, Paula; Valenzuela, Camila; Bernal Bayard, Joaquín; Escoll, Pedro; Genética
Intracellular survival and replication within macrophages are key virulence determinants of Salmonella enterica serovar Typhimurium. This phenomenon is traditionally attributed to the activity of its two Type III Secretion Systems (T3SS) and their associated effectors. A critical challenge for these bacteria is acquiring nutrients from inside the host cell. Thus, they modulate the metabolism of host cells to replicate. Given the metabolic plasticity of macrophages, a key unresolved question is how their metabolic heterogeneity shapes intracellular Salmonella replication. By using human primary macrophages and live-cell imaging to monitor bacterial dynamics at the single-cell level, we revealed that Salmonella does not replicate in all infected cells. However, supplementation with specific carbon sources used by Salmonella during infection accelerated bacterial replication and increased the proportion of macrophages harboring replicative bacteria. Remarkably, this occurred even in the absence of functional T3SSs, as a ΔprgH/ΔssaV double mutant was able to replicate in a subset of infected cells under favorable nutrient conditions. These phenotypes are further amplified in macrophages with higher glycolytic activity, such as the murine RAW 264.7 cell line. Further analyses demonstrated that enhanced Salmonella replication is not strictly dependent on host glycolytic activity but is instead driven by the ability of the host cell to take up the nutrients Salmonella prefers for its replication early during infection. In summary, our findings suggest that the dependence of Salmonella on its T3SSs for intracellular replication can be compensated, at least partially, when host cells provide optimal access to key nutrients. This underscores the role of host cell metabolism in shaping intracellular bacterial replication and highlights the crucial functions of T3SS effectors in remodelling macrophage metabolism and endosomal trafficking to establish nutrient-permissive niches. When equivalent metabolic conditions are achieved by other means in vitro, dependence on T3SSs for intracellular replication can be partially compensated in macrophages.
REDD1/DDIT4 counteracts endoplasmic reticulum stressinduced apoptosis by controlling the expression of death receptor TRAILR2/DR5 in cancer cells
(Springer Nature, 2026-03-28) Mora-Molina, Rocío; El Yousfi, Younes; Hagenlocher, Cathrin; Fernández-Farrán, Francisco Javier; Rehm, Markus; Palacios, Carmen; Christophorou, Maria A.; López-Rivas, Abelardo; Genética; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; European Union (UE); Deutsche Forschungsgemeinschaft / German Research Foundation (DFG)
Regulated in development and DNA damage response-1 (REDD1/DDIT4) is induced in response to environmental stress to restrain the mechanistic target of rapamycin complex 1 (mTORC1) signaling as an adaptive strategy to restore cellular homeostasis. Interestingly, REDD1/DDIT4 expression is upregulated in several tumor types including colorectal cancer, suggesting it may have a role in tumourigenesis. Here, we report that activating transcription factor 4 (ATF4)-dependent REDD1/DDIT4 expression is required for survival of colon tumor cells undergoing endoplasmic reticulum (ER) stress through the modulation of TRAILR2/DR5 gene expression. Our findings further demonstrate that resistance to ER stress-induced apoptosis in multicellular tumor spheroids (MCTS) is associated with constitutive expression of REDD1/DDIT4 and diminished mTORC1 activity. CRISPR/Cas9-mediated deletion of REDD1/DDIT4 markedly increases TRAILR2/DR5 expression and enhances apoptosis in spheroids exposed to ER stress. Interestingly, RNA sequencing analysis reveals that the loss of the transcriptional regulator EVI-1/MECOM in cells deficient in REDD1/DDIT4 amplifies the ER stress-induced upregulation of TRAILR2/DR5, leading to enhanced apoptosis. In summary, our findings underscore the crucial role of REDD1/DDIT4 in regulating TRAILR2/DR5-induced caspase-8 activation and apoptosis under chronic ER stress, by inhibiting mTORC1 activity and promoting EVI-1/MECOM-mediated suppression of TRAILR2/DR5 gene expression.
Editorial: Enrique Cerdá-Olmedo: An Outstanding Scientistand Mentor
(2026-04-02) Ávalos Cordero, Francisco Javier; Corrochano Peláez, Luis María; Genética
Data of transcriptional effects of the merbarone-me diate d inhibition of TOP2
(Elsevier, 2022-08-01) Delgado-Chaves, Fernando M.; Martínez García, Pedro Manuel; Herrero Ruiz, Andrés M.; Gómez-Vela, Francisco A.; Divina, Federico; Jimeno González, Silvia; Cortés Ledesma, Felipe; Genética; European Union (UE); Universidad Pablo de Olavide
Type II DNA topoisomerases relax topological stress by tran- siently gating DNA passage in a controlled cut-and-reseal mechanism that affects both DNA strands. Therefore, they are essential to overcome topological problems associated with DNA metabolism. Their aberrant activity results in the gener- ation of DNA double-strand breaks, which can seriously com- promise cell survival and genome integrity. Here, we profile the transcriptome of human-telomerase-immortalized retinal pigment epithelial 1 (RPE-1) cells when treated with mer- barone, a drug that catalytically inhibits type II DNA topoi- somerases. We performed RNA-Seq after 4 and 8 h of mer- barone treatment and compared transcriptional profiles ver- sus untreated samples. We report raw sequencing data to- gether with lists of gene counts and differentially expressed genes.
Determining the Age of Every Cell Within Each Budding Yeast Microcolony Combining Single-Cell Microencapsulation With Confocal Microscopy
(Bio-Protocol, 2026-09-05) Ruger Herreros, Carmen; Delgado Román, Irene; García Marcelo, María José; Chávez de Diego, Sebastián; Muñoz Centeno, María de la Cruz; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; Junta de Andalucía; Universidad de Sevilla
Isogenic populations of Saccharomyces cerevisiae exhibit significant proliferative heterogeneity, with individual cells within a clonal culture displaying divergent growth rates and metabolic states. Investigating the origins of this variation requires a method to reconstruct the individual histories of cells within the population. This protocol describes a method for single-cell microencapsulation in alginate microspheres to create a physically stable, traceable, three-dimensional genealogical environment. By utilizing the alginate matrix to prevent daughter cell migration, the replicative history of a founder cell can be mathematically reconstructed. This is achieved by correlating the total cell count (N) within a developed microcolony with the total number of accumulated bud scars (n) visualized via confocal microscopy.
Mechanisms of Quality Control in GPI-Anchored Proteins: The Central Role of the Lipid Anchor
(MDPI, 2026-07-16) Lemus Rodríguez,Leticia; Satpute-Krishnan, Prasanna; Goder, Veit; Genética; Agencia Estatal de Investigación. España; National Institutes of Health. United States
Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are a distinct class of eukaryotic cell-surface proteins characterized by a glycolipid anchor at their C-terminus. They display unique biophysical properties and play important roles in human diseases, including transmissible spongiform encephalopathies (TSEs), malaria, sleeping sickness, and rare disorders collectively termed inherited GPI deficiency (IGD). Because of their broad clinical relevance, GPI-APs have become a major focus of research, including their intracellular quality control (QC). Studies in diverse model organisms have revealed striking interspecies differences in GPI-AP QC pathways and notable distinctions from QC mechanisms and the degradation of misfolded species governing other secretory proteins. In this review, we summarize recent advances in the understanding of these cellular processes and propose that the observed variations in QC reflect distinct cellular strategies that balance protein QC with membrane homeostasis across evolutionary contexts.
Radiobiology studies of gold nanoparticle-enhanced radiosensitization in proton therapy
(Wiley, 2026-08) Fuster Martínez, Nuria; Saucedo Cuberes, Demetrio Hermenegildo; Jiménez Ramos, María del Carmen; Esperante Pereira, Daniel; Espino Navas, José Manuel; González López, Lucía; Huertas Sánchez, Pablo; Jimeno González, Sonia; Suárez García, Daniel; García Murria, María Jesús; Física Aplicada II; Física Atómica, Molecular y Nuclear; Genética; Centro Nacional de Aceleradores (CNA); Centro Andaluz de Investigaciones en Biología Molecular y Medicina Regenerativa (CABIMER); Generalitat Valenciana; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Fundación Científica Asociación Española Contra el Cáncer; RNM138: Física Nuclear Aplicada; FQM160: Física Nuclear Básica; BIO026: Metabolismo del DNA
Background: Approximately 50% of newly diagnosed cancer patients worldwide receive radiotherapy, most commonly with X-rays. Proton therapy has emerged as a promising alternative, offering complementary advantages over conventional X-rays due to its highly localized energy deposition at the Bragg peak, thereby reducing radiation exposure to surrounding healthy tissues. In recent years, advances in both technology and biomedicine have driven significant progress in proton therapy, with ongoing research aiming to minimize toxicity and long-term side effects while improving patients’ quality of life. An emerging research direction investigates the combination of proton therapy with irradiated nanoparticles acting as radiosensitizers. This approach seeks synergistic effects that could further improve therapeutic outcomes. These effects arise from a complex interplay of physical,chemical,and biological mechanisms. Although previous in vitro and in vivo studies report promising radiosensitization effects of nanoparticles, the literature also includes contradictory results, and the underlying mechanisms remain under debate. This highlighting the need for systematic studies under well-controlled irradiation conditions of different nanoparticles and beam parameters, which are often difficult to perform due to the limited availability of particle accelerators and facilities suitably adapted for such experiments. Purpose: This work investigates the radiosensitizing effect of gold anoparticles under proton irradiation and optimizes the irradiation setup to enable more efficient and reproducible future experiments. Methods: HeLa cells were used as the biological model for the radiobiological experiments. Irradiation conditions were optimized by incorporating a Mylar film into the culture plates to maintain a minimal medium volume and ensure rapid post-irradiation coverage. Cells with and without AuNPs were irradiated with 12.6 MeV proton beams. Radiosensitivity was assessed using clonogenic survival assays, and the radiosensitizing effect, together with its associated uncertainty, was quantified. DNA damage analysis was also performed to corroborate the observed effects and explore underlying mechanisms. Results: The radiobiology experiments confirmed and quantified a significant radiosensitizing effect of gold nanoparticles (AuNPs) on HeLa cells at doses from 4 Gy, with Sensitization Enhancement Ratio (SER) values of 1.53 ± 0.07 in 2022 and 1.30 ± 0.20 in 2023 using 50 nm diameter AuNPs. Experiments in 2023 with 20 nm diameter AuNPs yielded a comparable SER of 1.38 ± 0.18, indicating no significant size-dependent differences. The radiosensitizing effect exhibited dose-dependent amplification, with higher doses producing greater cell killing.Linear-Quadratic (LQ) model fits showed an increased 𝛼 parameter in the presence of AuNPs, consistent with an increase in non-repairable damage. This trend was further supported by double-strand break assays. Furthermore, oxidative stress assays showed that AuNPs do not increase basal ROS levels, but enhance ROS production under oxidative stress conditions. Conclusion: The radiobiology experiments presented quantitatively confirm that both 20 and 50 nm diameter AuNPs enhance the radiosensitivity of HeLa cells under proton irradiation. The radiosensitizing effect increases with dose, indicating a dose-dependent response, while no significant differences were observed between nanoparticle sizes. Consistent trends of increased DNA double-strand breaks further support the observed radiosensitization. Evidence from oxidative stress assays suggests that AuNPs may enhance ROS production under oxidative conditions, potentially contributing to the observed radiosensitization and DNA damage.
A desynchrony mechanism between events triggers a compensatory delay during Caenorhabditis elegans development
(Public Library of Science, 2026-07-24) Romero Expósito, Francisco Javier; Moreno Rivero, Almudena; Muñoz Barrera, Marta; Gritti, Nicola; Sartor, Francesca; Merrow, Martha; Zon, Jeroen S. van; Mata Cabana, Alejandro; Olmedo López, María; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; Junta de Andalucía
In multicellular organisms, development entails the progression of diverse cellular processes that need to be temporally coordinated. During Caenorhabditis elegans postembryonic development, the events of molting and cell divisions progress in parallel during four larval stages and are modulated by external cues such as temperature and nutrient availability. While seam cell divisions occur predominantly before ecdysis of the cuticle, the order of the events can change, suggesting that they are controlled by independent mechanisms. Here, we have analyzed the impact of reduced insulin signaling on molting and in stage-specific cell divisions. We find that reduced insulin signaling in the daf-2(e1370) allele delays both events but has a larger impact on the timing of cell divisions, thus increasing the desynchrony between the events. The relative delay in seam cell divisions leads to a delay in the initiation of the subsequent stage of the molting program, providing a mechanism for resynchronization of developmental processes at the beginning of the larval stages.
P-Sulfocalix[6]arene as Nanocarrier for Controlled Delivery of Doxorubicin
(Wiley, 2017-01-23) Ostos Marcos, Francisco José; Lebrón Romero, José Antonio; Moyá Morán, María Luisa; López-López, Manuel; Sánchez, Antonio; Clavero, Amparo; García-Calderón, Clara B.; Valle Rosado, Iván; López-Cornejo, María del Pilar; Química Física; Genética; Junta de Andalucía; European Union (UE)
Given the high toxicity of the anthracycline antibiotic called doxorubicin (DOX), it is relevant to look for nanocarriers that, decreasing the side effects of the drug, were able to transport it towards a therapeutic target. Accordingly, the encapsulation of DOX by p-sulfocalix[6]arene (calix) has been studied. The interaction of DOX with the macrocycle, as well as with DNA, has been investigated and the equilibrium constant for each binding process estimated. Results showed that the binding constant of DOX to DNA, KDNA, is three orders of magnitude higher than that to calix, Kcalix. A multidisciplinary study has been done to demonstrate the ability of calixarenes to encapsulate DOX molecules, as well as the power of the DOX molecules included into the inner cavity of the macrocycle to bind with the DNA. Citotoxicity measurements were done in different cancer cell lines to probe the decrease in the toxicity of the encapsulated DOX, demonstrating thus the decrease of its side effects in the human organism. The low toxicity of calixarenes has also been demonstrated for different cancer cell lines.
Mitochondrial redox homeostasis links organellar stress surveillance to germline and somatic integrity in Caenorhabditis elegans
(Elsevier, 2026-03-09) Valenzuela-Villatoro, Marina; Cruz-Ruiz, Patricia de la; Guerrero Gómez, David; Gómez-Orte, Eva; Schiavi, Alfonso; Maglioni, Silvia; Montero, Mayte; Fonteriz, Rosalba I.; Olmedo López, María; Miranda-Vizuete, Antonio; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE); National Institutes of Health. United States; Deutsche Forschungsgemeinschaft
Mitochondrial redox homeostasis is essential for cellular metabolism and organismal development. To investigate the consequences of disrupting redox homeostasis in this organelle in a metazoan organism, we generated a double mutant lacking mitochondrial glutathione reductase (gsr-1a) and thioredoxin reductase (trxr-2) genes in Caenorhabditis elegans. While gsr-1a or trxr-2 single mutants are phenotypically normal, double gsr-1a trxr-2 mutants displayed small body size, gonadal migration defects, reduced brood size, and prolonged egg-laying period, without developmental delay or lethality. Transcriptomic analysis revealed strong induction of ATFS-1-dependent stress and detoxification genes. Consistent with this, gsr-1a trxr-2 worms exhibited constitutive ATFS-1 nuclear localization and robust Phsp-6::gfp expression. Triple gsr-1a trxr-2; atfs-1 mutants were nonviable, demonstrating that unfolded protein response (UPRmt) activation is essential under mitochondrial redox stress. Despite the induction of a stress response at the transcriptional level, gsr-1a trxr-2 double mutants were not more resistant to oxidative or pathogen stressors. Moreover, these mutants maintained normal respiration, ATP and ROS production while displaying altered mitochondrial morphology in a tissue-specific manner, independent of mitophagy genes but dependent on mitochondrial fission or fusion machinery. Functionally, gsr-1a trxr-2 mutants showed impaired motility, reduced calcium uptake upon carbachol stimulation, enhanced hypodermal wound repair, and decreased fertilization efficiency associated with lower muscle exopher production. Overall, our data show that simultaneous loss of mitochondrial GSR-1a and TRXR-2 compromises growth, fertility and muscle performance and triggers a constitutive ATFS-1-dependent UPRmt that sustains viability revealing mitochondrial redox control as a core determinant of organismal proteostasis.
Dbf4-dependent kinase finetunes Ino80 function at chromosome replication origins
(Springer Science and Business Media LLC, 2026) Bansal, Priyanka; Lahiri, Shibojyoti; Kumar, Chadni Natalia; Furtmeier, Jessica; Spechtenhauser, Lorenz; Galanti, Lorenzo; Ortíz-Bazán, María Ángeles; Aguilera López, Andrés; Gómez González, Belén; Kurat, Christoph F.; Genética; Deutsche Forschungsgemeinschaft / German Research Foundation (DFG); European Union (UE); Junta de Andalucía
The highly conserved Dbf4-Dependent Kinase (DDK) plays a pivotal role during S phase. It phosphorylates the replicative helicase (minichromosome maintenance, MCM complex), which leads to the initiation of replication. However, few other targets, besides the MCM complex, are known, leaving DDK an understudied kinase. Here, we determine the nuclear DDK-dependent phosphoproteome by a two-pronged mass spectrometry approach. Among ~ 400 DDK-dependent phosphorylation targets, we find the Arp8 subunit of the INO80 chromatin remodeling complex. Arp8 phosphorylation stabilises INO80’s complex integrity, finetunes its nucleosome spacing at replication origins, stimulates replication and improves the replication stress response. Taken together, we report the regulation of a chromatin remodeler with nucleosome-spacing activity by the cell-cycle machinery. DDK not only regulates the core replication machinery but also regulates a factor that generates replication-conducive chromatin architecture at replication origins.
Enhancing the performance of Magnets photosensors
(Nature Research, 2026-02-18) Baumschlager, Armin; Weber, Yanik; Cánovas López, David; Dionisi, Sara; Khammash, Mustafa; Genética
Photosensory protein domains, derived from nature, are foundational for optogenetic protein engineering. Tailoring their properties enables their full exploitation for optogenetic regulation in basic research and applied bioengineering applications. Here, we present a simple, yet powerful strategy based on random mutagenesis coupled to high-throughput screening that allowed altering the most fundamental properties of the widely used nMag/pMag photodimerization system: its light sensitivity and activation. Variants were characterized in vivo in bacteria by flow cytometry and during the entire growth curve by spectrofluorometry. We identify mutations that either increase or decrease the light sensitivity at sub-saturating light intensities, while also improving the light activation and dark-to-light fold change. Notably, light sensitivity and activation levels could be changed independently. In addition, we demonstrated that the shapes of the dose-response curves can be finely tuned. This broadens the applicability of the Magnets photosensors for optogenetic regulation strategies.
How fungi see the world: fungal photoreceptors and their role in the regulation of fungal biology
(American Society for Microbiology, 2025-08-11) Corrochano Peláez, Luis María; Gutiérrez Pozo, Gabriel; Corrochano Luque, María; Franco Cano, Antonio; Cánovas López, David; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España
Fungi use light as a signal for the regulation of development, to guide the growth of reproductive structures, and to protect the fungal cell from DNA damage produced by light and UV radiation. Light perception requires the activity of photoreceptors that relay the light signal through transduction pathways into the cellular response. Fungi can see and react to a wide range of colors, but most fungi use blue light as their primary signal to regulate its photobiology. Examples of fungal perception of UV, green, and red light, like plants, have been documented and, in most cases, the photoreceptors responsible for these responses have been identified. Blue light is perceived through the activity of light-regulated transcription factors, the WC proteins, first identified in Neurospora crassa. Red light is perceived by phytochromes, a photoreceptor characterized in detail in Aspergillus nidulans. A novel type of rhodopsin, rhodopsin guanylyl cyclase (RGS) has been identified in the zoosporic fungus Blastocladiella emersonii. These types of photoreceptors, together with the blue-light photoreceptor cryptochrome, are widespread in fungi, suggesting that the ancestor of the fungi could see a wide range of colors. Gene duplication and specialization have allowed specific use of fungal photoreceptors in the regulation of fungal biology.
Light sensing in fungi
(Cell Press (Elsevier), 2025-12-01) Corrochano Peláez, Luis María; Corrochano Luque, María; Franco Cano, Antonio; Gutiérrez Pozo, Gabriel; Cánovas López, David; Genética
Light is essential for life as it provides the energy for the growth of plants and photosynthetic microorganisms. Plants use the energy from light to fix carbon dioxide and produce oxygen, and their photosynthetic apparatus includes sensory systems that optimize light detection. For example, light is a signal that regulates plant growth and promotes the development and orientation of leaves so that they can optimize the capture of the light energy for photosynthesis. Light is also an environmental signal that is used by non-photosynthetic organisms for their orientation, to obtain food and capture prey or to escape from predators, and to anticipate daily or seasonal changes caused by the rotation of the earth. Fungi, for example, do not use light as a source of energy, but rather light is a signal that regulates fungal development and the orientation of the growth of fruiting bodies to optimize the dispersal of spores. In this primer we describe how fungi react to light, the types of photoreceptors that they use to sense light, and the mechanisms of photoreception in a few model fungi. In addition, we will discuss the origin of fungal photoreception, and we will propose future research directions.
Measurement of rRNA Synthesis and Degradation Rates by 3H-Uracil Labeling in Yeast
(Humana, 2024-11-14) García Marcelo, María José; Singh, Gaurav; Chávez de Diego, Sebastián; Pérez Ortín, José E.; Genética
In order to measure the actual synthesis and degradation rates (SR, DR) for rRNA in yeast, we developed a method based on the pulse labeling and quantification of newly synthesized large rRNA molecules by a known mass of cells. The SR is calculated as the ratio of new rRNA molecules (synthesized after a short [5,6-3H]-uracil pulse) to total rRNA (a proxy of cell mass), calculated by northern blotting after hybridization with a 32P-labeled rRNA probe. Then to measure the DR we perform a chase of the existing 3H-labeled rRNA for several hours during yeast culture growth. We have used this method in control experiments where the yeast cell volume varies as a way to check if the SR and DR are constant with the cell volume.
DICER ribonuclease removes harmful R-loops
(Elsevier, 2023-10-19) Pérez de Camino Cantos, Dolores; Dutta, Arijit; Barroso Ceballos, Sonia Inés; Pérez-Calero, Carmen; Katz, Jeffrey N.; García Rubio, María Luisa; Sung, Patrick; Gómez González, Belén; Aguilera López, Andrés; Genética; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España
R-loops, which consist of a DNA-RNA hybrid and a displaced DNA strand, are known to threaten genome integrity. To counteract this, different mechanisms suppress R-loop accumulation by either preventing the hybridization of RNA with the DNA template (RNA biogenesis factors), unwinding the hybrid (DNA-RNA helicases), or degrading the RNA moiety of the R-loop (RNases H). Thus far, type H RNases are the only nucleases known to cleave DNA-RNA hybrids. Now, we show that the RNase DICER also resolves R-loops. Biochemical analysis reveals that DICER acts by specifically cleaving the RNA within R-loops. Importantly, a DICER RNase mutant impaired in R-loop processing causes a strong accumulation of R-loops in cells. Our results, thus, not only reveal a function of DICER as an R-loop resolvase independent of DROSHA, but also provide evidence for the role of multifunctional RNA processing factors in the maintenance of genome integrity in higher eukaryotes.
FANCD2 restrains fork progression and prevents fragility at early origins upon re-replication
(Springer Nature, 2026-02-07) Badra Fajardo, Nibal; Karydi, Elena; Bayona Feliu, Aleix; Gómez González, Belén; Preza, Ourania; Arbi, Marina; Kalogeropoulou, Argyro; Rantala, Juha K.; Taraviras, Stavros; Aguilera López, Andrés; Lygerou, Zoi; Genética; European Union (UE); Hellenic Foundation for Research and Innovation; Agencia Estatal de Investigación. España; Caixa Research Foundation
DNA replication is tightly regulated to ensure a single round of chromosome duplication per cell division. DNA licensing restricts origin firing to once-per-cell-cycle while aberrant licensing promotes re-replication and genome instability. Here, we investigate the mechanisms that protect genome integrity following re-replication induced by depletion of the licensing inhibitor Geminin. We find that re-replicating cells require FANCD2 to prevent genome instability. FANCD2 is rapidly recruited to chromatin upon Geminin loss, where it limits unrestrained fork progression and prevents single strand DNA gap accumulation and fork breakage. Genome-wide analyses reveal that upon re-replication, FANCD2 localizes to early origins within highly transcribed regions prone to accumulate R-loops and enriched in early replicating fragile sites. Importantly, reducing transcription and R-loops alleviates re-replication-induced genome fragility, whereas PARP inhibition exacerbates it. Our study uncovers a role for FANCD2 in safeguarding genome integrity during re-replication, offering avenues for selective targeting of cancer cells.
The many ways to inhibit translation by Sorafenib in liver cancer cells
(Springer, 2025-09-15) Contreras Bernal, Laura; Ricciardi, Sara; Biffo, Stefano; Muntané Relat, Jordi; Cruz Díaz, Jesús de la; Genética; Fisiología Médica y Biofísica; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Instituto de Salud Carlos III
Sorafenib targets various tyrosine kinase receptors, inhibiting cell growth and proliferation, angiogenesis and metastasis in tumour cells. It is used to treat certain types of cancers including renal, thyroid and liver (hepatocellular carcinoma) cancers. Although Sorafenib is approved for advanced hepatocellular carcinoma, it only extends patient´s lives by a few months, highlighting the urgent need to better understand how it works and to develop more effective treatments. Sorafenib specifically inhibits translation initiation in hepatocellular carcinoma cells. Herein, we revealed that this inhibition results, at least, from the activation of PERK, triggering a stress response that leads to eIF2α phosphorylation, the inhibition of MNK1a-signalling-dependent eIF4E phosphorylation, and the aberrant assembly of the canonical eIF4F complex. Sorafenib also inhibits the ERK1/2 MAPK signalling in HepG2 cells. However, the mTORC1 pathway does appear to play a pivotal role in Sorafenib-dependent translation inhibition, as revealed by the phosphorylation levels of RPS6 and 4EBP1 proteins and the effects on translation of gene silencing 4EBP1/2 in Sorafenib-treated cells. Translation inhibition correlates with reduced production of cancer-promoting proteins like Cyclin D1 and c-Myc. Overexpression of the phosphomimetic eIF4E-S209D variant, which constitutively activates eIF4E, shows that inhibition of eIF4E phosphorylation directly causes Cyclin D1 down-regulation and cell-cycle delay in Sorafenib-treated cells. Taken together, our results confirm that Sorafenib induces translation reprogramming, whose understanding is crucial for improving its efficacy as a cancer therapy.
An essential gene screening identifies yeast Mot1 as a suppressor of R-loops and genome instability
(Public Library of Science, 2026-02-09) Soler Oliva, María Eugenia; Domínguez Sierra, Rocío de los Ángeles; Gaillard, Hélène; Aguilera López, Andrés; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Research Council (ERC); Fundación de Investigación de la Universidad de Sevilla
Transcription is essential for cellular function, but it can also lead to genetic instability, particularly through the formation of secondary structures such as R-loops, which consist of an RNA-DNA hybrid and a displaced DNA strand. Unscheduled R-loop accumulation is a major source of DNA damage and has been associated with several human diseases, including cancer. While multiple factors involved in RNA biogenesis, export, and chromatin remodeling play a role in preventing R-loop accumulation, the function of essential proteins in R-loop metabolism remains unexplored. Here, we performed a genetic screening in Saccharomyces cerevisiae using over 1200 temperature-sensitive mutants to identify novel proteins involved in the prevention of R-loop-associated genomic instability. Our results reveal that the SWI/SNF-like protein Mot1 plays a key role in preventing R-loop accumulation and R-loop-associated genome instability. Its role is particularly important during S phase, where Mot1 dysfunction leads to R-loop dependent replication impairment, presumably due to transcription-replication conflicts (TRCs). Epistatic relationships between mutations in MOT1 and the S-phase specific DNA-RNA helicase SEN1 further support the role of Mot1 in TRCs. The study highlights the importance of transcriptional regulators in maintaining genome stability by mitigating TRCs and regulating R-loop homeostasis.
The DExD-box RNA helicase Dbp7 unwinds short double-stranded RNAs
(Elsevier, 2026-02-12) Contreras Fernández, Julia Mª; Capeyrou, Régine; Henry, Yves; Henras, Anthony K.; Humbert, Odile; Cruz Díaz, Jesús de la; Villalobo Polo, Eduardo; Genética; Microbiología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agence Nationale de la Recherche. France
DExD-box proteins are ATP-dependent enzymes that unwind double-stranded RNAs in a non-processive manner, often initiating strand separation from 5′- or 3′-single-stranded overhangs. Dbp7, a member of this family, is required for yeast ribosome biogenesis and has been specifically implicated in the release of the small nucleolar RNA snR190 from early pre-60S particles. To gain mechanistic insight into its function, we have examined the in vitro helicase activity of recombinant Dbp7. We show that it efficiently unwinds short double-stranded RNA substrates in an ATP-dependent manner, irrespective of overhang polarity, thereby establishing it as a bona fide DExD-box RNA helicase.

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