Biology subjects

Fidalgo, M.

Publications and source records attributed to Fidalgo, M..

5 recordsLinked to original sources

bioRxiv2026

The Holliday junction resolvase GEN1 preserves genome integrity and self-renewal in mouse embryonic stem cells

The maintenance of pluripotent stem cells (PSCs) under rapid proliferation requires mechanisms that both suppress replication-driven genome instability and preserve self-renewal capacity. Here, we show that, in contrast to somatic cells where it mainly acts as a backup, the Holliday junction resolvase GEN1 is required in mouse embryonic stem cells (ESCs), where its depletion severely compromises self-renewal and long-term maintenance. Loss of GEN1 induces the accumulation of cells with DNA content greater than 4C and chromosome fusions. Notably, a catalytically inactive GEN1 mutant rescues ESC colony formation, indicating that GEN1 supports ESC maintenance through non-enzymatic functions. In addition, GEN1 depletion increases ESC tolerance to topoisomerase I-mediated replication stress and renders this phenotype dependent on DNA-PK activity, suggesting that GEN1 loss alters how pluripotent cells cope with replication-associated DNA lesions. Together, these findings identify GEN1 as a non-redundant guardian of genome integrity in pluripotent cells, revealing both a catalysis-independent role in self-renewal and a contribution to the replication stress response, with implications for PSC genomic quality control. HighlightsO_LIIn contrast to somatic cells, GEN1 is specifically required for mouse pluripotent cell self-renewal and expansion in vitro. C_LIO_LIGEN1 loss induces accumulation of DNA content greater than 4C and chromosome fusions without loss of core pluripotency markers expression. C_LIO_LICatalytically inactive GEN1 mutant rescues ESC colony-forming capacity. C_LIO_LIGEN1 depletion increases ESC tolerance to topoisomerase I-mediated replication stress in a DNA-PK-dependent manner C_LI eTOCRamos-Lage et al. demonstrate that the resolvase GEN1 is essential for mouse embryonic stem cell self-renewal and genome stability. Strikingly, a catalytically dead mutant rescues colony formation, revealing an unexpected non-enzymatic role for GEN1 in pluripotency maintenance.

cell biology↗

bioRxiv2026

Inhibition of p107 alleviates liver steatosis by reducing de novo fatty acid synthesis.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by excessive hepatic lipid accumulation driven by increased de novo lipogenesis (DNL) and impaired lipid oxidation. p107, a member of the retinoblastoma (Rb) family, extensively studied in the context of cell cycle regulation and adipocyte differentiation recently has been identified as a metabolic regulator controlling thermogenic activity. However, its role in hepatic lipid homeostasis remains poorly understood. Here, we identify the cell cycle regulator p107 as a key modulator of hepatic lipid metabolism. p107 expression is increased in patients with MASLD and correlates with disease severity. In mouse models, global and liver-specific p107 deficiency protect against high-fat diet-induced steatosis without affecting body weight. This is associated with reduced expression of lipogenic enzymes including fatty acid synthase (FASN), and enhanced mitochondrial oxidative pathways. Conversely, hepatic restoration of p107 reversed these effects and promoted lipid accumulation and endoplasmic reticulum stress. Consistent with this in human hepatocytes, p107 silencing reduces lipid accumulation, decreases DNL and enhances mitochondrial respiration, whereas p107 overexpression induces the opposite phenotype. Notably, FASN knockdown attenuates the pro-steatotic effects of p107, indicating that it is a critical downstream mediator of p107. Together, these findings establish p107 as a physiological regulator of hepatic lipid metabolism, with its dysregulation contributing to the development of MASLD.

physiology↗

bioRxiv2025

Rapamycin can revert CCM phenotype in brain endothelial cells and ameliorates chronic cavernoma development in combination with lapatinib

This study investigates the impact of rapamycin and propranolol on cerebral cavernous malformations (CCMs). Employing an unbiased transcriptomic analysis, we aimed to comprehensively elucidate the molecular mechanisms underlying these drug effects in Mouse Brain Microvascular Endothelial Cells (mBMEC) deficient in Ccm3. While propranolol shows limited efficacy in modulating the CCM transcriptomic phenotype in mBMEC, rapamycin demonstrates a higher impact. Rapamycin reverses gene expression changes induced by Ccm3 deficiency, restoring Klf2/4-dependent genes like Nos3, Adamts1, and Thbs1. Notably, we observed a reduction in KLF2 protein levels in Ccm3 KO cells treated with rapamycin. Critically, in vivo experiments demonstrate that a combination of rapamycin and lapatinib effectively reduces lesion volume in a chronic CCM model. This finding is particularly noteworthy as it suggests a potential treatment strategy for existing lesions. In summary, our work describes a new mechanism for the effects of rapamycin in Ccm3- deficient cells and identifies a new drug combination in the treatment of cavernomas.

cell biology↗

bioRxiv2025

An astrocytic AMPK clock drives circadian behaviour

Circadian clocks coordinate behaviour and physiology with daily cycles of light and nutrient availability, but how metabolic signals influence brain timing remains incompletely understood. Astrocytes integrate metabolic and hormonal cues and exhibit time-of-day-dependent responses, suggesting that they may convey temporal information to hypothalamic circuits. Here, we show that hypothalamic AMP-activated protein kinase (AMPK) exhibits circadian regulation independently of light and feeding cues, is modulated by nutrient availability and astrocytic Ca{superscript 2} signalling, and regulates the temporal organisation of the hypothalamic phosphoproteome. Genetic manipulation of astrocytic AMPK signalling alters PER2 abundance and phosphorylation, including at a conserved residue implicated in circadian period regulation. At the behavioural level, AMPK and PER2 in ventromedial hypothalamic astrocytes contribute to food-anticipatory activity, whereas disruption of astrocytic AMPK signalling alters SCN-dependent circadian locomotor rhythms and energy homeostasis in a sex-dependent manner. Together, these findings identify astrocytic AMPK signalling as a temporally regulated pathway that couples metabolic signals to hypothalamic circadian timing and systemic homeostasis.

neuroscience↗

bioRxiv2025

Transcription factor 19 is an androgen responsive gene that modulates vessel homeostasis and sustains metastatic prostate cancer

Prostate cancer is a prevalent tumor type that, despite being highly curable, progresses to metastatic disease in a fraction of patients, thus accounting for more than 350.000 annual deaths worldwide. In turn, uncovering the molecular insights of metastatic disease is instrumental to improve the survival rate of prostate cancer patients. By means of gene expression metanalysis in multiple prostate cancer patient cohorts, we identified a set of genes that are differentially expressed in aggressive prostate cancer. Transcription factor 19 (TCF19) stood out as an unprecedented epithelial gene upregulated in metastatic disease, with prognostic potential and associated with the activity of androgen receptor. By combining computational and empiric approaches, our data revealed that TCF19 is required for full metastatic capacity and its depletion influences core cancer-related processes, such as vascular permeability, supporting the role of this gene in the dissemination of prostate tumor cells.

cancer biology↗