The integrated stress response drives MET oncogene overexpression in cancers.

Cancer cells rely on invasive growth to survive in a hostile microenvironment; this growth is characterised by interconnected processes such as epithelial-to-mesenchymal transition and migration. A master regulator of these events is the MET oncogene, which is overexpressed in the majority of cancers; however, since mutations in the MET oncogene are seen only rarely in cancers and are relatively infrequent, the mechanisms that cause this widespread MET overexpression remain obscure. Here, we show that the 5' untranslated region (5'UTR) of MET mRNA harbours two functional stress-responsive elements, conferring translational regulation by the integrated stress response (ISR), regulated by phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) at serine 52.

A multiparametric screen uncovers FDA-approved small molecules that potentiate the nuclear mechano-dysfunctions in ATR-defective cells.

Targeting nuclear mechanics is emerging as a promising therapeutic strategy for sensitizing cancer cells to immunotherapy. Inhibition of the mechano-sensory kinase ATR leads to mechanical vulnerability of cancer cells, causing nuclear envelope softness and collapse and activation of the cGAS-STING-mediated innate immune response. Finding novel compounds that interfere with the non-canonical role of ATR in controlling nuclear mechanics presents an intriguing therapeutic opportunity.

Early downmodulation of tumor glycolysis predicts response to fasting-mimicking diet in triple-negative breast cancer patients.

In preclinical experiments, cyclic fasting-mimicking diets (FMDs) showed broad anticancer effects in combination with chemotherapy. Among different tumor types, triple-negative breast cancer (TNBC) is exquisitely sensitive to FMD. However, the antitumor activity and efficacy of cyclic FMD in TNBC patients remain unclear.

Mechanical stress during confined migration causes aberrant mitoses and c-MYC amplification.

Confined cell migration hampers genome integrity and activates the ATR and ATM mechano-transduction pathways. We investigated whether the mechanical stress generated by metastatic interstitial migration contributes to the enhanced chromosomal instability observed in metastatic tumor cells. We employed live cell imaging, micro-fluidic approaches, and scRNA-seq to follow the fate of tumor cells experiencing confined migration.

Sch9 controls DNA repair and DNA damage response efficiency in aging cells.

Survival from UV-induced DNA lesions relies on nucleotide excision repair (NER) and the Mec1 DNA damage response (DDR). We study DDR and NER in aging cells and find that old cells struggle to repair DNA and activate Mec1. We employ pharmacological and genetic approaches to rescue DDR and NER during aging.

Blocking lipid synthesis induces DNA damage in prostate cancer and increases cell death caused by PARP inhibition.

Androgen deprivation therapy (ADT) is the primary treatment for prostate cancer; however, resistance to ADT invariably develops, leading to castration-resistant prostate cancer (CRPC). Prostate cancer progression is marked by increased de novo synthesis of fatty acids due to overexpression of fatty acid synthase (FASN), making this enzyme a therapeutic target for prostate cancer. Inhibition of FASN results in increased intracellular amounts of ceramides and sphingomyelin, leading to DNA damage through the formation of DNA double-strand breaks and cell death.

Cell stretching activates an ATM mechano-transduction pathway that remodels cytoskeleton and chromatin.

Ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) DNA damage response (DDR) kinases contain elastic domains. ATM also responds to reactive oxygen species (ROS) and ATR to nuclear mechanical stress. Mre11 mediates ATM activation following DNA damage; ATM mutations cause ataxia telangiectasia (A-T).

Mechanisms controlling the mechanical properties of the nuclei.

The mechanical properties of the nucleus influence different cellular and nuclear functions and have relevant implications for several human diseases. The nucleus protects genetic information while acting as a mechano-sensory hub in response to internal and external forces. Cells have evolved mechano-transduction signaling to respond to physical cellular and nuclear perturbations and adopted a multitude of molecular pathways to maintain nuclear shape stability and prevent morphological abnormalities of the nucleus.

Sen1 and Rrm3 ensure permissive topological conditions for replication termination.

Replication forks terminate at TERs and telomeres. Forks that converge or encounter transcription generate topological stress. Combining genetics, genomics, and transmission electron microscopy, we find that Rrm3 and Sen1 helicases assist termination at TERs; Sen1 specifically acts at telomeres.

Tissue fluidification promotes a cGAS-STING cytosolic DNA response in invasive breast cancer.

The process in which locally confined epithelial malignancies progressively evolve into invasive cancers is often promoted by unjamming, a phase transition from a solid-like to a liquid-like state, which occurs in various tissues. Whether this tissue-level mechanical transition impacts phenotypes during carcinoma progression remains unclear. Here we report that the large fluctuations in cell density that accompany unjamming result in repeated mechanical deformations of cells and nuclei.

Cancer cell histone density links global histone acetylation, mitochondrial proteome and histone acetylase inhibitor sensitivity.

Chromatin metabolism is frequently altered in cancer cells and facilitates cancer development. While cancer cells produce large amounts of histones, the protein component of chromatin packaging, during replication, the potential impact of histone density on cancer biology has not been studied systematically. Here, we show that altered histone density affects global histone acetylation, histone deactylase inhibitor sensitivity and altered mitochondrial proteome composition.

Pressure Overload Activates DNA-Damage Response in Cardiac Stromal Cells: A Novel Mechanism Behind Heart Failure With Preserved Ejection Fraction?

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome characterized by impaired left ventricular (LV) diastolic function, with normal LV ejection fraction. Aortic valve stenosis can cause an HFpEF-like syndrome by inducing sustained pressure overload (PO) and cardiac remodeling, as cardiomyocyte (CM) hypertrophy and fibrotic matrix deposition. Recently, studies linked PO maladaptive myocardial changes and DNA damage response (DDR) activation: DDR-persistent activation contributes to mouse CM hypertrophy and inflammation, promoting tissue remodeling, and HF.

YAP/TAZ activity in stromal cells prevents ageing by controlling cGAS-STING.

Ageing is intimately connected to the induction of cell senescence, but why this is so remains poorly understood. A key challenge is the identification of pathways that normally suppress senescence, are lost during ageing and are functionally relevant to oppose ageing. Here we connected the structural and functional decline of ageing tissues to attenuated function of the master effectors of cellular mechanosignalling YAP and TAZ.

Topology of RNA:DNA Hybrids and R-Loops in Yeast.

RNA:DNA hybrids are generated naturally behind the elongating RNA polymerase as a transcriptional intermediate. However, prolonged persistence of these structures challenges the integrity of the genome by creating R-loops and by interfering with DNA replication and other chromatin related processes. Precise mapping and characterization of their distribution across the genome has been a major challenge to understand the genesis of RNA:DNA hybrids and their conversion into genotoxic intermediates.

The transcription factor PREP1(PKNOX1) regulates nuclear stiffness, the expression of LINC complex proteins and mechanotransduction.

Mechanosignaling, initiated by extracellular forces and propagated through the intracellular cytoskeletal network, triggers signaling cascades employed in processes as embryogenesis, tissue maintenance and disease development. While signal transduction by transcription factors occurs downstream of cellular mechanosensing, little is known about the cell intrinsic mechanisms that can regulate mechanosignaling. Here we show that transcription factor PREP1 (PKNOX1) regulates the stiffness of the nucleus, the expression of LINC complex proteins and mechanotransduction of YAP-TAZ.

Vps30/Atg6/BECN1 at the crossroads between cell metabolism and DNA damage response.

Several cytotoxic agents used in cancer therapy cause DNA damage and replication stress. Understanding the metabolic determinants of the cell response to replication stress-inducing agents could have relevant implications for cancer treatment. In a recent study, we showed that cell survival during replication stress is influenced by the availability of amino acids, as well as by TORC1 and Gcn2-mediated amino acid sensing pathways.

The ESCRT machinery counteracts Nesprin-2G-mediated mechanical forces during nuclear envelope repair.

Transient nuclear envelope ruptures during interphase (NERDI) occur due to cytoskeletal compressive forces at sites of weakened lamina, and delayed NERDI repair results in genomic instability. Nuclear envelope (NE) sealing is completed by endosomal sorting complex required for transport (ESCRT) machinery. A key unanswered question is how local compressive forces are counteracted to allow efficient membrane resealing.

Fasting-Mimicking Diet Is Safe and Reshapes Metabolism and Antitumor Immunity in Patients with Cancer.

In tumor-bearing mice, cyclic fasting or fasting-mimicking diets (FMD) enhance the activity of antineoplastic treatments by modulating systemic metabolism and boosting antitumor immunity. Here we conducted a clinical trial to investigate the safety and biological effects of cyclic, five-day FMD in combination with standard antitumor therapies. In 101 patients, the FMD was safe, feasible, and resulted in a consistent decrease of blood glucose and growth factor concentration, thus recapitulating metabolic changes that mediate fasting/FMD anticancer effects in preclinical experiments.

Palmdelphin Regulates Nuclear Resilience to Mechanical Stress in the Endothelium.

Background: PALMD (palmdelphin) belongs to the family of paralemmin proteins implicated in cytoskeletal regulation. Single nucleotide polymorphisms in the locus that result in reduced expression are strong risk factors for development of calcific aortic valve stenosis and predict severity of the disease.

Methods: Immunodetection and public database screening showed dominant expression of PALMD in endothelial cells (ECs) in brain and cardiovascular tissues including aortic valves.

Endosomal trafficking and DNA damage checkpoint kinases dictate survival to replication stress by regulating amino acid uptake and protein synthesis.

Atg6 mediates autophagy and endosomal trafficking. We investigated how Atg6 influences replication stress. Combining genetic, genomic, metabolomic, and proteomic approaches, we found that the Vps34-Vps15-Atg6-Vps38-phosphatydilinositol-3 phosphate (PtdIns(3)P) axis sensitizes cells to replication stress by favoring the degradation of plasma membrane amino acid (AA) transporters via endosomal trafficking and ESCRT proteins, while the PtdIns(3)P phosphatases Ymr1 and Inp53 promote survival to replication stress by reversing this process.

A rapid method to visualize human mitochondrial DNA replication through rotary shadowing and transmission electron microscopy.

We report a rapid experimental procedure based on high-density in vivo psoralen inter-strand DNA cross-linking coupled to spreading of naked purified DNA, positive staining, low-angle rotary shadowing, and transmission electron microscopy (TEM) that allows quick visualization of the dynamic of heavy strand (HS) and light strand (LS) human mitochondrial DNA replication. Replication maps built on linearized mitochondrial genomes and optimized rotary shadowing conditions enable clear visualization of the progression of the mitochondrial DNA synthesis and visualization of replication intermediates carrying long single-strand DNA stretches. One variant of this technique, called denaturing spreading, allowed the inspection of the fine chromatin structure of the mitochondrial genome and was applied to visualize the in vivo three-strand DNA structure of the human mitochondrial D-loop intermediate with unprecedented clarity.

HnRNP K mislocalisation is a novel protein pathology of frontotemporal lobar degeneration and ageing and leads to cryptic splicing.

Heterogeneous nuclear ribonucleoproteins (HnRNPs) are a group of ubiquitously expressed RNA-binding proteins implicated in the regulation of all aspects of nucleic acid metabolism. HnRNP K is a member of this highly versatile hnRNP family. Pathological redistribution of hnRNP K to the cytoplasm has been linked to the pathogenesis of several malignancies but, until now, has been underexplored in the context of neurodegenerative disease.