Switching of RNA splicing regulators in immature neuroblasts during adult neurogenesis.

The lateral wall of the mouse subventricular zone harbors neural stem cells (NSC, B cells) which generate proliferating transient-amplifying progenitors (TAP, C cells) that ultimately give rise to neuroblasts (NB, A cells). Molecular profiling at the single-cell level struggles to distinguish these different cell types. Here, we combined transcriptome analyses of FACS-sorted cells and single-cell RNAseq to demonstrate the existence of an abundant, clonogenic and multipotent population of immature neuroblasts (iNB cells) at the transition between TAP and migrating NB (mNB).

Loss of CD24 promotes radiation‑ and chemo‑resistance by inducing stemness properties associated with a hybrid E/M state in breast cancer cells.

Cancer stem cells (CSCs) serve an essential role in failure of conventional antitumor therapy. In breast cancer, CD24/CD44 phenotype and high aldehyde dehydrogenase activity are associated with CSC subtypes. Furthermore, CD24/CD44 pattern is also characteristic of mesenchymal cells generated by epithelial‑mesenchymal transition (EMT).

Phospho-Ku70 induced by DNA damage interacts with RNA Pol II and promotes the formation of phospho-53BP1 foci to ensure optimal cNHEJ.

Canonical non-homologous end-joining (cNHEJ) is the prominent mammalian DNA double-strand breaks (DSBs) repair pathway operative throughout the cell cycle. Phosphorylation of Ku70 at ser27-ser33 (pKu70) is induced by DNA DSBs and has been shown to regulate cNHEJ activity, but the underlying mechanism remained unknown. Here, we established that following DNA damage induction, Ku70 moves from nucleoli to the sites of damage, and once linked to DNA, it is phosphorylated.

Lamin B1 sequesters 53BP1 to control its recruitment to DNA damage.

Double-strand breaks (DSBs) are harmful lesions and a major cause of genome instability. Studies have suggested a link between the nuclear envelope and the DNA damage response. Here, we show that lamin B1, a major component of the nuclear envelope, interacts directly with 53BP1 protein, which plays a pivotal role in the DSB repair.

Abnormal migration behavior linked to Rac1 signaling contributes to primordial germ cell exhaustion in Fanconi anemia pathway-deficient Fancg-/- embryos.

Fanconi anemia (FA) is a rare human genetic disorder characterized by bone marrow failure, predisposition to cancer and developmental defects including hypogonadism. Reproductive defects leading to germ cell aplasia are the most consistent phenotypes seen in FA mouse models. We examined the role of the nuclear FA core complex gene Fancg in the development of primordial germ cells (PGCs), the embryonic precursors of adult gametes, during fetal development.

Syndecan-1 Stimulates Adult Neurogenesis in the Mouse Ventricular-Subventricular Zone after Injury.

The production of neurons from neural stem cells (NSCs) persists throughout life in the mouse ventricular-subventricular zone (V-SVZ). We have previously reported that NSCs from adult V-SVZ are contained in cell populations expressing the carbohydrate SSEA-1/LeX, which exhibit either characteristics of quiescent NSCs (qNSCs) or of actively dividing NSCs (aNSCs) based on the absence or the presence of EGF-receptor, respectively. Using the fluorescence ubiquitination cell cycle indicator-Cdt1 transgenic mice to mark cells in G/G phase of the cell cycle, we uncovered a subpopulation of qNSCs which were primed to enter the cell cycle .

Higher chromosome stability in embryonic neural stem and progenitor cells than in fibroblasts in response to acute or chronic genotoxic stress.

High fidelity of genetic transmission in neural stem and progenitor cells (NSPCs) has been long time considered to be crucial for brain development and homeostasis. However, recent studies have identified recurrent DSB clusters in dividing NSPCs, which may underlie the diversity of neuronal cell types. This raised the interest in understanding how NSPCs sense and repair DSBs and how this mechanism could be altered by environmental genotoxic stress caused by pollutants or ionizing radiation.

Electroporation as a vaccine delivery system and a natural adjuvant to intradermal administration of plasmid DNA in macaques.

In vivo electroporation (EP) is used to enhance the uptake of nucleic acids and its association with DNA vaccination greatly stimulates immune responses to vaccine antigens delivered through the skin. However, the effect of EP on cutaneous cell behavior, the dynamics of immune cell recruitment and local inflammatory factors, have not been fully described. Here, we show that intradermal DNA vaccination combined with EP extends antigen expression to the epidermis and the subcutaneous skin muscle in non-human primates.

ComB proteins expression levels determine Helicobacter pylori competence capacity.

Helicobacter pylori chronically colonises half of the world's human population and is the main cause of ulcers and gastric cancers. Its prevalence and the increase in antibiotic resistance observed recently reflect the high genetic adaptability of this pathogen. Together with high mutation rates and an efficient DNA recombination system, horizontal gene transfer through natural competence makes of H.

Following transforming DNA in Helicobacter pylori from uptake to expression.

Natural transformation is a potent driver for genetic diversification in bacterial populations. It involves exogenous DNA binding, uptake, transport and internalization into the cytoplasm, where DNA can be processed and integrated into the host chromosome. Direct visualisation of transforming DNA (tDNA) has been limited to its binding to the surface or, in the case of Gram-negative species, to its entrance into the periplasm.

Intradermal injection of an anti-Langerin-HIVGag fusion vaccine targets epidermal Langerhans cells in nonhuman primates and can be tracked in vivo.

The development of new immunization strategies requires a better understanding of early molecular and cellular events occurring at the site of injection. The skin is particularly rich in immune cells and represents an attractive site for vaccine administration. Here, we specifically targeted vaccine antigens to epidermal Langerhans cells (LCs) using a fusion protein composed of HIV antigens and a monoclonal antibody targeting Langerin.

Cell Sorting of Neural Stem and Progenitor Cells from the Adult Mouse Subventricular Zone and Live-imaging of their Cell Cycle Dynamics.

Neural stem cells (NSCs) in the subventricular zone of the lateral ventricles (SVZ) sustain olfactory neurogenesis throughout life in the mammalian brain. They successively generate transit amplifying cells (TACs) and neuroblasts that differentiate into neurons once they integrate the olfactory bulbs. Emerging fluorescent activated cell sorting (FACS) techniques have allowed the isolation of NSCs as well as their progeny and have started to shed light on gene regulatory networks in adult neurogenic niches.

Specific uptake and genotoxicity induced by polystyrene nanobeads with distinct surface chemistry on human lung epithelial cells and macrophages.

Nanoparticle surface chemistry is known to play a crucial role in interactions with cells and their related cytotoxic effects. As inhalation is a major route of exposure to nanoparticles, we studied specific uptake and damages of well-characterized fluorescent 50 nm polystyrene (PS) nanobeads harboring different functionalized surfaces (non-functionalized, carboxylated and aminated) on pulmonary epithelial cells and macrophages (Calu-3 and THP-1 cell lines respectively). Cytotoxicity of in mass dye-labeled functionalized PS nanobeads was assessed by xCELLigence system and alamarBlue viability assay.

Interaction with OGG1 is required for efficient recruitment of XRCC1 to base excision repair and maintenance of genetic stability after exposure to oxidative stress.

XRCC1 is an essential protein required for the maintenance of genomic stability through its implication in DNA repair. The main function of XRCC1 is associated with its role in the single-strand break (SSB) and base excision repair (BER) pathways that share several enzymatic steps. We show here that the polymorphic XRCC1 variant R194W presents a defect in its interaction with the DNA glycosylase OGG1 after oxidative stress.

The Notch Delta-4 ligand helps to maintain the quiescence and the short-term reconstitutive potential of haematopoietic progenitor cells through activation of a key gene network.

Understanding the role of Notch and its ligands within the different bone marrow niches could shed light on the mechanisms regulating haematopoietic progenitor cells (HPCs) maintenance and self-renewal. Here, we report that murine bone marrow HPCs activation by the vascular Notch Delta-4 ligand maintains a significant proportion of cells specifically in the G0 state. Furthermore, Delta-4/Notch pathway limits significantly the loss of the in vivo short-term reconstitutive potential upon transplantation of Delta-4 activated HPCs into lethally irradiated recipient mice.

Assessment of an model of pulmonary barrier to study the translocation of nanoparticles.

As the lung is one of the main routes of exposure to manufactured nanoparticles, we developed an model resembling the alveolo-capillary barrier for the study of nanoparticle translocation. In order to provide a relevant and ethical model, cost effective and easy-to-implement human cell lines were used. Pulmonary epithelial cells (Calu-3 cell line) and macrophages (THP-1 differentiated cells) were cultivated on the apical side and pulmonary endothelial cells (HPMEC-ST1.

Distinct spatiotemporal patterns and PARP dependence of XRCC1 recruitment to single-strand break and base excision repair.

Single-strand break repair (SSBR) and base excision repair (BER) of modified bases and abasic sites share several players. Among them is XRCC1, an essential scaffold protein with no enzymatic activity, required for the coordination of both pathways. XRCC1 is recruited to SSBR by PARP-1, responsible for the initial recognition of the break.

Cell cooperation and role of the P2X₇ receptor in pulmonary inflammation induced by nanoparticles.

Macrophages and alveolar epithelial cells are the first targets of inhaled nanoparticles (NPs) reaching the alveoli. Mono- or co-cultures of lung epithelial (A549 or NCI-H441) and macrophage (THP-1) cell lines were used to study the cell cooperation and the involvement of the P2X₇ cell death receptor during the inflammation caused by SiO₂ and TiO₂ NPs. Here we show that, secretion of pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) in response to NPs exposure was higher in co-cultures than in mono-cultures.

Unveiling novel RecO distant orthologues involved in homologous recombination.

The generation of a RecA filament on single-stranded DNA is a critical step in homologous recombination. Two main pathways leading to the formation of the nucleofilament have been identified in bacteria, based on the protein complexes mediating RecA loading: RecBCD (AddAB) and RecFOR. Many bacterial species seem to lack some of the components involved in these complexes.

Novel microarray-based method for estimating exposure to ionizing radiation.

Accurate estimation of the dose of ionizing radiation to which individuals have been exposed is critical for therapeutic treatment. We investigated whether gene expression profiles could be used to evaluate the dose received, thereby serving as a biological dosimeter. We used cDNA microarrays to monitor changes in gene expression profiles induced by ionizing radiation in mouse total blood.

Novel pathway for megakaryocyte production after in vivo conditional eradication of integrin alphaIIb-expressing cells.

Our knowledge of the molecular mechanisms that regulate hematopoiesis in physiologic and pathologic conditions is limited. Using a molecular approach based on cDNA microarrays, we demonstrated the emergence of an alternative pathway for mature bone marrow cell recovery after the programmed and reversible eradication of CD41+ cells in transgenic mice expressing a conditional toxigene targeted by the platelet alphaIIb promoter. The expression profile of the newly produced CD41+ cells showed high levels of transcripts encoding Ezh2, TdT, Rag2, and various immunoglobulin (Ig) heavy chains.

Gene expression in aging kidney and pituitary.

Gene expression in aging kidney and pituitary was determined by subtractive hybridization, DNA microarrays and RT-PCR. Kidneys and pituitary were removed from 10- and 30-month-old female WAG/Rij rats, which were free from chronic progressive nephrosis and had a low incidence of pituitary tumors with age. From 350 cDNA fragments isolated by subtractive hybridization, just one showed a more than twofold change in expression between 10 and 30 months.