812 research outputs found
Defining the clonal dynamics leading to mouse skin tumour initiation.
The changes in cell dynamics after oncogenic mutation that lead to the development of tumours are currently unknown. Here, using skin epidermis as a model, we assessed the effect of oncogenic hedgehog signalling in distinct cell populations and their capacity to induce basal cell carcinoma, the most frequent cancer in humans. We found that only stem cells, and not progenitors, initiated tumour formation upon oncogenic hedgehog signalling. This difference was due to the hierarchical organization of tumour growth in oncogene-targeted stem cells, characterized by an increase in symmetric self-renewing divisions and a higher p53-dependent resistance to apoptosis, leading to rapid clonal expansion and progression into invasive tumours. Our work reveals that the capacity of oncogene-targeted cells to induce tumour formation is dependent not only on their long-term survival and expansion, but also on the specific clonal dynamics of the cancer cell of origin.C.B. is an investigator of WELBIO. A.S-D. and JC.L. are supported by a fellowship of the FNRS and FRIA respectively. B.D.S. and E.H. are supported by the Wellcome Trust (grant number 098357/Z/12/Z and 110326/Z/15/Z). EH is supported by a fellowship from Trinity College, Cambridge. This work was supported by the FNRS, the IUAP program, the Fondation contre le Cancer, the ULB fondation, the foundation Bettencourt Schueller, the foundation Baillet Latour, a consolidator grant of the European Research Council.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nature1906
BrainWAVE: A flexible method for noninvasive stimulation of brain rhythms across species
Rhythmic neural activity, which coordinates brain regions and neurons to achieve multiple brain functions, is impaired in many diseases. Despite the therapeutic potential of driving brain rhythms, methods to noninvasively target deep brain regions are limited. Accordingly, we recently introduced a noninvasive stimulation approach using flickering lights and sounds ( flicker ). Flicker drives rhythmic activity in deep and superficial brain regions. Gamma flicker spurs immune function, clears pathogens, and rescues memory performance in mice with amyloid pathology. Here, we present substantial improvements to this approach that is flexible, user-friendly, and generalizable across multiple experimental settings and species. We present novel open-source methods for flicker stimulation across rodents and humans. We demonstrate rapid, cross-species induction of rhythmic activity without behavioral confounds in multiple settings from electrophysiology to neuroimaging. This flicker approach provides an exceptional opportunity to discover the therapeutic effects of brain rhythms across scales and species
Clonal Dynamics Reveal Two Distinct Populations of Basal Cells in Slow-Turnover Airway Epithelium.
Epithelial lineages have been studied at cellular resolution in multiple organs that turn over rapidly. However, many epithelia, including those of the lung, liver, pancreas, and prostate, turn over slowly and may be regulated differently. We investigated the mouse tracheal epithelial lineage at homeostasis by using long-term clonal analysis and mathematical modeling. This pseudostratified epithelium contains basal cells and secretory and multiciliated luminal cells. Our analysis revealed that basal cells are heterogeneous, comprising approximately equal numbers of multipotent stem cells and committed precursors, which persist in the basal layer for 11 days before differentiating to luminal fate. We confirmed the molecular and functional differences within the basal population by using single-cell qRT-PCR and further lineage labeling. Additionally, we show that self-renewal of short-lived secretory cells is a feature of homeostasis. We have thus revealed early luminal commitment of cells that are morphologically indistinguishable from stem cells.This study was supported by the Medical Research Council (G0900424 to E.R.), European Union grant EuroSyStem (200720; FP7/2008), the Newton Trust (to E.R.), the Wellcome Trust (098357/Z/12/Z to B.D.S.). Core grants from the Wellcome Trust (092096) and Cancer Research UK (C6946/A14492).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.celrep.2015.06.01
Multisensory flicker modulates widespread brain networks and reduces interictal epileptiform discharges
Modulating brain oscillations has strong therapeutic potential. Interventions that both non-invasively modulate deep brain structures and are practical for chronic daily home use are desirable for a variety of therapeutic applications. Repetitive audio-visual stimulation, or sensory flicker, is an accessible approach that modulates hippocampus in mice, but its effects in humans are poorly defined. We therefore quantified the neurophysiological effects of flicker with high spatiotemporal resolution in patients with focal epilepsy who underwent intracranial seizure monitoring. In this interventional trial (NCT04188834) with a cross-over design, subjects underwent different frequencies of flicker stimulation in the same recording session with the effect of sensory flicker exposure on local field potential (LFP) power and interictal epileptiform discharges (IEDs) as primary and secondary outcomes, respectively. Flicker focally modulated local field potentials in expected canonical sensory cortices but also in the medial temporal lobe and prefrontal cortex, likely via resonance of stimulated long-range circuits. Moreover, flicker decreased interictal epileptiform discharges, a pathological biomarker of epilepsy and degenerative diseases, most strongly in regions where potentials were flicker-modulated, especially the visual cortex and medial temporal lobe. This trial met the scientific goal and is now closed. Our findings reveal how multi-sensory stimulation may modulate cortical structures to mitigate pathological activity in humans
Cyclic dermal BMP signalling regulates stem cell activation during hair regeneration
In the age of stem cell engineering it is critical to understand how stem cell activity is regulated during regeneration. Hairs are mini-organs that undergo cyclic regeneration throughout adult life1, and are an important model for organ regeneration. Hair stem cells located in the follicle bulge2 are regulated by the surrounding microenvironment, or niche3. The activation of such stem cells is cyclic, involving periodic -catenin activity4, 5, 6, 7. In the adult mouse, regeneration occurs in waves in a follicle population, implying coordination among adjacent follicles and the extrafollicular environment. Here we show that unexpected periodic expression of bone morphogenetic protein 2 (Bmp2) and Bmp4 in the dermis regulates this process. This BMP cycle is out of phase with the WNT/-catenin cycle, thus dividing the conventional telogen into new functional phases: one refractory and the other competent for hair regeneration, characterized by high and low BMP signalling, respectively. Overexpression of noggin, a BMP antagonist, in mouse skin resulted in a markedly shortened refractory phase and faster propagation of the regenerative wave. Transplantation of skin from this mutant onto a wild-type host showed that follicles in donor and host can affect their cycling behaviours mutually, with the outcome depending on the equilibrium of BMP activity in the dermis. Administration of BMP4 protein caused the competent region to become refractory. These results show that BMPs may be the long-sought 'chalone' inhibitors of hair growth postulated by classical experiments. Taken together, results presented in this study provide an example of hierarchical regulation of local organ stem cell homeostasis by the inter-organ macroenvironment. The expression of Bmp2 in subcutaneous adipocytes indicates physiological integration between these two thermo-regulatory organs. Our findings have practical importance for studies using mouse skin as a model for carcinogenesis, intra-cutaneous drug delivery and stem cell engineering studies, because they highlight the acute need to differentiate supportive versus inhibitory regions in the host skin
Universality of clone dynamics during tissue development.
The emergence of complex organs is driven by the coordinated proliferation, migration and differentiation of precursor cells. The fate behaviour of these cells is reflected in the time evolution their progeny, termed clones, which serve as a key experimental observable. In adult tissues, where cell dynamics is constrained by the condition of homeostasis, clonal tracing studies based on transgenic animal models have advanced our understanding of cell fate behaviour and its dysregulation in disease (1, 2). But what can be learned from clonal dynamics in development, where the spatial cohesiveness of clones is impaired by tissue deformations during tissue growth? Drawing on the results of clonal tracing studies, we show that, despite the complexity of organ development, clonal dynamics may converge to a critical state characterized by universal scaling behaviour of clone sizes. By mapping clonal dynamics onto a generalization of the classical theory of aerosols, we elucidate the origin and range of scaling behaviours and show how the identification of universal scaling dependences may allow lineage-specific information to be distilled from experiments. Our study shows the emergence of core concepts of statistical physics in an unexpected context, identifying cellular systems as a laboratory to study non-equilibrium statistical physics.Wellcome Trus
Local Microenvironment Provides Important Cues for Cell Differentiation in Lingual Epithelia
Transgenic Keratin14-rtTA-PTR mice specifically express Keratin14 (K14) in the tongue epithelia, as well as co-express EGFP and the dominant negative ÎTgfbr2 genes upon treatment with Doxycycline (Dox). As TGF-ÎČ signaling negatively regulates the stem cell cycle and proliferation, its disruption by Dox induction in these transgenic mice shortens the cell cycle and allows observation of the final fate of those mutated cell lineages within a short period of time. Here, we used inducible transgenic mice to track the K14+ cells through the cell migration stream by immunohistochemical an immunofluorescent imaging. We showed that these cells have different development patterns from the tip to posterior of the tongue, achieved presumably by integrating positional information from the microenvironment. The expression of the K14 gene was variable, depending on the location of the tongue and papillae. Disruption of TGF-ÎČ signaling in K14+ progenitor cells resulted in proliferation of stem cell pools
The role of CC chemokine receptor 5 (CCR5) and RANTES/CCL5 during chronic fungal asthma in mice1
In the present study, we explored the role of CC chemokine receptor 5 (CCR5) in a murine model of chronic fungal asthma induced by an intrapulmonary challenge with Aspergillus fumigatus conidia (or spores). Airway hyperresponsiveness was significantly lower in A. fumigatusâsensitized mice lacking CCR5 (CCR5â/â) compared with similarly sensitized wildâtype (CCR5+/+) control mice at days 2, 21, 30, and 40 after the conidia challenge. CCR5â/â mice exhibited significantly less peribronchial Tâcell and eosinophil accumulation and airwayâremodeling features, such as goblet cell hyperplasia and peribronchial fibrosis, compared with CCR5+/+ mice at these times after conidia. However, both groups of mice exhibited similar allergic airway disease at day 12 after the conidia challenge. In CCR5â/â mice at day 12, the allergic airway disease was associated with airway hyperresponsiveness, peribronchial allergic inflammation, and goblet cell hyperplasia. Immunoneutralization of RANTES/CCL5 in sensitized CCR5+/+ and CCR5â/â mice for 12 days after the conidia challenge significantly reduced the peribronchial inflammation and airway hyperresponsiveness in comparison with control wildâtype and knockout mice at this time. These data demonstrate that functional CCR5 and RANTES/CCL5 are required for the persistence of chronic fungal asthma in mice.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154329/1/fsb2fj010528fje.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154329/2/fsb2fj010528fje-sup-0001.pd
- âŠ