Merkel cell carcinoma (MCC) is a highly aggressive skin cancer with rising global incidence. Merkel cell polyomavirus (MCV) was discovered in 2008 in 80% of MCC samples and since then a causal link between MCV and the majority of MCC cases has been established. microRNAs (miRNA, miR) are a family of small non-coding RNAs which play a key role in post-transcriptional regulation of gene expression and are considered significant players in disease and development in many species. Whilst the focus of MCV research has thus far been on the oncogenic MCV early proteins, large tumour (LT) and small tumour (sT) antigens, there is a knowledge gap regarding MCV miRNA and its functional significance in MCV pathogenesis. Given the emerging importance of viral miRNAs in virus-host interaction and pathogenesis, the aim of this doctoral research project was to investigate alterations in host cell transcripts induced by MCV miRNA and determine any functional significance these might have on virus-host cell interaction. RNA sequencing (RNA-Seq) in the presence and absence of MCV miRNA uncovered a multitude of downregulated cellular transcripts. Gene ontology analysis revealed that MCV miRNA targets transcripts associated with multiple cellular processes, however, regulation of immune response was overrepresented in our datasets. Validation of RNA-Seq data using MCV miRNA mimics and a synthetic, fully replicative MCV genome (MCVSyn) confirmed RNA-Seq data at mRNA and protein expression level for several targets, including the cytokine stimulating gene, SP100, and the neutrophil stimulator chemokine, CXCL8. Moreover, dual luciferase assays revealed that SP100 and MAPK10 (a member of mitogen-activated protein kinases (MAPK) family which is involved in regulation of CXCL8 expression) are directly and specifically targeted and downregulated by MCV miRNA. The MCV miRNA-dependent dysregulation of CXCL8 secretion is associated with impaired neutrophil migration, suggesting that the virus miRNA may be implicated in evasion of the host immune response.

This problem is an analytical study of the needs and interests of the Merkel Community to determine the contents to be used in formulating a course of study in electricity for the secondary school, if it is found it meets with the needs and desires of the community.

The skin epidermis ensures critical vital functions: it represents the first line of defense against external aggressions.<p>The Epidermal Proliferative Unit (EPU) and the stochastic model are two opposite theories that have been proposed to explain the homeostasis of the interfollicular epidermis (IFE). During my thesis, we addressed this question. We used two inducible CREER transgenic mouse models (K14CREER and InvCREER) to labeled basal cells of the IFE using the RosaYFP reporter system, allowing us to follow their fate. Using confocal microscopy to analyze the basal YFP positive clones induced, we demonstrated the existence of two distinct basal progenitors. The mathematical modeling of our data set confirmed this observation and clearly demonstrated the existence of a quiescent stem cell (SC) population (targeted by the K14 promoter), which eventually gives rise to a more rapidly proliferating cells, the committed progenitors (CPs, targeted by the Inv promoter) that participate actively to replace the IFE cells lost during the normal turnover of the tissue. By using an independent genetic mouse model (K5tTA tetO-H2BGFP) and by studying the transcriptional profiling of the two basal populations, we confirmed our hypothesis, and thus reconciling the two seemingly opposite EPU and stochastic models. Finally, we challenged the function of the K14 SCs and Inv CPs during IFE wound healing. Conversely to what happens during homeostasis, we observed that SCs are massively proliferating and participating to the repair and maintenance of the damaged area, while CPs are poorly recruited to the wound.<p>The skin is also a highly sensitive organ, which contains many different receptors specialized in a precise sensation, and richly innervated by somatosensory neurons.<p>The Merkel Cells (MCs) are mechanoreceptors present in the basal layer of the IFE that have features of both neurons and keratinocytes, and might be implicated in the development of a rare but very aggressive skin tumor. Since their discovery in 1875, many studies claimed the neural crest cells (NCCs) or the epidermal progenitors are at the origin of MC, but no clear evidence has been proposed. <p>During my thesis, we were also interested in the embryonic origin of the MC. We used different transgenic mouse models to assess the NCC (Wnt1CRE and Pax3CRE RosaYFP) and the epidermal (K14CRE RosaYFP) hypotheses and we finally demonstrated that MC arise from embryonic epidermal progenitors. Using induction of adult epidermis transgenic mouse (K14CREER RosaYFP, K15CREPR RosaYFP), we showed that the epidermis also participates to the renewing of adult MC. Finally, we deleted the Math1 gene in all the MC progenitors (K14CRE Mathfl/fl) of mouse embryos, resulting in the absence of MCs in adult mice, demonstrating the importance of this transcription factor for MCs specification during embryogenesis.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

<p>Kvinnor börjar i allt större grad slå sig in på den internationella politiska arenan. En arena som traditionellt endast haft plats för män i svarta kostymer. Att kvinnor tar plats på den internationella politiska arenan har också påverkat utrikesjournalistiken. Fler kvinnor syns i dag på dagspressens utrikessidor än vad det gjordes för 20 år sedan. Men hur framställs de kvinnliga politikerna i medierna när de framträder på en traditionell manlig arena? Genom att undersöka hur två EU-ordföranden, Angela Merkel och Matti Vanhanen, framställdes i textform under tre månader på Dagens Nyheters och Svenska Dagbladets utrikessidor försöker denna uppsats finna svaret på den frågan.</p><p>Med en kvantitativ innehållsanalys och en kritisk diskursanalys har artiklar analyserats utifrån ett genusperspektiv. Det är svårt att hitta ett tydligt mönster i resultaten.</p><p>Den kvantitativa delen av studien visar att Merkel får väsentligt mycket mer uppmärksamhet som EU-ordförande än Vanhanen. Den kvalitativa studien visar emellertid att en typ av ifrågasättande omgärdar framställningen av Merkel. Merkel fick även stå till svars för sina uttalanden själv. Motsvarande tendens gäller inte för Vanhanen.</p><p>Även om det kan vara svårt att dra några säkra slutsatser av undersökningen så har jag funnit att det finns en skillnad utifrån ett genusperspektiv i hur Merkel och Vanhanen framställdes på de två undersökta tidningarnas utrikessidor. Denna skillnad kan dock bero på andra orsaker, som till exempel maktförhållanden mellan små och stora länder inom EU.</p>

Kvinnor börjar i allt större grad slå sig in på den internationella politiska arenan. En arena som traditionellt endast haft plats för män i svarta kostymer. Att kvinnor tar plats på den internationella politiska arenan har också påverkat utrikesjournalistiken. Fler kvinnor syns i dag på dagspressens utrikessidor än vad det gjordes för 20 år sedan. Men hur framställs de kvinnliga politikerna i medierna när de framträder på en traditionell manlig arena? Genom att undersöka hur två EU-ordföranden, Angela Merkel och Matti Vanhanen, framställdes i textform under tre månader på Dagens Nyheters och Svenska Dagbladets utrikessidor försöker denna uppsats finna svaret på den frågan. Med en kvantitativ innehållsanalys och en kritisk diskursanalys har artiklar analyserats utifrån ett genusperspektiv. Det är svårt att hitta ett tydligt mönster i resultaten. Den kvantitativa delen av studien visar att Merkel får väsentligt mycket mer uppmärksamhet som EU-ordförande än Vanhanen. Den kvalitativa studien visar emellertid att en typ av ifrågasättande omgärdar framställningen av Merkel. Merkel fick även stå till svars för sina uttalanden själv. Motsvarande tendens gäller inte för Vanhanen. Även om det kan vara svårt att dra några säkra slutsatser av undersökningen så har jag funnit att det finns en skillnad utifrån ett genusperspektiv i hur Merkel och Vanhanen framställdes på de två undersökta tidningarnas utrikessidor. Denna skillnad kan dock bero på andra orsaker, som till exempel maktförhållanden mellan små och stora länder inom EU.

Thesis (doctoral)--Hochschule Vechta, 2010. / Includes bibliographic references (p. 221-244).

Multicellular organisms typically depend on O₂ for energy production to maintain normal cellular function, and even brief periods of O₂ deprivation may have fatal consequences. The aqueous environment is prone to changes in ambient water O₂ tension (PO₂) and thus the ability of fish to sense changes in water PO₂ and to elicit appropriate physiological responses is essential for their survival. Studies on fish O₂ chemoreception have identified neuroepithelial cells (NECs), which are characterized as having dense-cored vesicles containing serotonin (5-HT), as peripheral O₂ chemoreceptors. Upon exposure to hypoxia, isolated and cultured NECs in vitro depolarize, likely resulting in neurotransmitter release. However, to date there is no evidence that NECs are activated by hypoxia in vivo to initiate physiological responses such as the hypoxic ventilatory response (HVR), which is the focus of this thesis. Initial findings demonstrated that larval zebrafish fine-tune the HVR as early as 4 days post fertilization (dpf) and by 7 dpf, the HVR aids in O₂ uptake under hypoxic conditions. In addition, the HVR is multiphasic, with an initiation phase followed by a decline phase that gradually stabilizes above normoxic baseline values (Chapter 2). In the absence of tools to probe the hypoxia sensitivity of NECs in vivo, research focused on Merkel-like cells (MLCs), a newly proposed O₂ chemoreceptor in larval zebrafish. Using in vivo calcium imaging it was shown that MLCs are stimulated by hypoxia. Data suggest that MLCs are responsible for the initiation phase of the HVR, while peripheral sensory neurons (PSNs)/peripheral sensory ganglia (PSG) that innervate MLCs play a more important role in reducing ventilation during the decline phase of the HVR (Chapter 4). Attempts at identifying the putative neurotransmitter(s) involved in the O₂ signal transduction pathway revealed that adrenaline (AD), serotonin (5-HT), and dopamine (DA) are probable candidates (Chapter 4), though the presence of AD and DA within MLCs is yet to be confirmed. In addition, 5-HT likely plays a role in the central nervous system (CNS), integrating peripheral signals resulting in the final HVR (Chapter 3). Taken together, this thesis provides the first evidence of putative O₂ chemoreceptors responding to hypoxia in vivo and thus significantly advances models for O₂ signal transduction in larval zebrafish.

No description available.

En 2008, le génome d'un nouveau virus a été caractérisé au sein d'un cancer cutané rare survenant préférentiellement chez l'immunodéprimé, le carcinome de Merkel. Ce nouveau virus appartenait à la famille des Polyomaviridae qui comprend des virus dont le caractère cancérigène chez l'animal est avéré depuis plus de 50 ans. Dénommé Polyomavirus de Merkel puisqu'il semblait lié à la survenue du cancer du même nom, il constituait le premier Polyomavirus impliqué de manière consistante dans un cancer humain. Cette implication reposant sur une étude unique limitée à 10 cas, l'objectif de notre travail de thèse était de confirmer le rôle étiologique du Polyomavirus de Merkel dans le carcinome de Merkel.Nous avons montré que le génome du Polyomavirus de Merkel était présent dans les trois quarts des cas de carcinome de Merkel, mais également que le virus infecte la population générale de manière quasi-ubiquitaire et de nombreux tissus en dehors de la peau. Les faits que chez les sujets atteints de carcinome de Merkel, l'ADN viral soit présent à des taux décelables de manière chronique dans différents tissus et que les titres d'anticorps sériques spécifiques du virus soient élevés suggèrent que ces sujets développent une infection chronique active. Celle-ci pourrait faciliter la survenue de mutations et d'intégrations de l'ADN viral qui sont spécifiquement associées aux carcinomes de Merkel. Ces modifications secondaires du génome viral aboutissent à la production d'oncoprotéines virales par les cellules tumorales, mais à l'abolition des capacités réplicatives donc lytiques du virus et constitueraient ainsi le support de la transformation tumorale.

La détection de la température externe par la peau est le point de départ de nombreuses adaptations cellulaires et comportementales permettant de maintenir notre température interne constante. Selon ce concept, les fibres sensorielles cutanées sont les seuls récepteurs sensoriels de la peau pour la détection de la température. Plusieurs canaux ioniques activés directement par des températures chaudes ou froides ont été identifiés, ce sont les canaux TRPs. Le froid peut-il modifier le fonctionnement des organes du toucher?Nous montrons chez l’homme et la souris que les cellules de Merkel (CMs), qui sont les cellules tactiles des complexes de Merkel, peuvent être activées par le froid. Chez les souris dépourvues du canal TRPM8 (KO M8) la réponse au froid des CMs diminue. Le BCTC et le M8B, 2 bloqueurs du canal TRPM8, diminuent également la réponse au froid des CMs. Pour déterminer l’impact de cette sensibilité au froid sur la performance tactile, nous avons enregistré les variations de l’activité nerveuse des récepteurs de Merkel chez les souris WT et KO M8. Un froid modéré (20°C) appliqué sur la peau diminue le train de potentiels d’action issu d’un récepteur de Merkel stimulé mécaniquement. A 20°C ni le seuil de déclenchement des potentiels d’action, ni le train de potentiels d’action en réponse à une stimulation électrique ne sont modifiés. En revanche chez les souris KO M8 cette réponse mécanique tactile n’est plus diminuée. Ce résultat montre pour la première fois qu’une cellule non nerveuse de la peau, la cellule de Merkel, contient un récepteur au froid, le canal TRPM8, qui ajuste l’activité des récepteurs de Merkel lors d’une stimulation tactile. / In the skin, Merkel cells (Mcs) are connected to keratinocytes and A sensory nerve fibers and the complexes works as a slow adaptive mechanoreceptor (SA1 receptor). We observe that cooling human and mouse Merkel cells to 15°C increases intracellular Ca2+ ions concentration. The TRPM8 agonist’s provoke intracellular Ca2+ increases. The responses to cooling and TRPM8 agonist’s are reduced in absence of extracellular Ca2+ ions, by the TRPM8 antagonist’s and in KO M8 mouse. These results show that MCs sense cooling through TRPM8 channels. We hypothesize that cooling sensitivity modulate mechano-transduction and we investigate the modulation of SA1 response using the skin nerve and microneurography techniques in mouse and human, respectively. In mouse, cooling the skin at 22°C reduces the frequency of the SA1 discharge, without modifying the nerve conduction. This reduction disappeared in KO M8 mouse. These results suggest that MCs activity reduced the discharge of SA1 receptor at mild fresh temperature, anticipating effect of lower temperature on A nerve fiber excitability.This study is the first report about the sensitivity of MCs to cold temperature and its consequences on the SA1 receptor activity in mouse and human. We conclude that cold sensitivity of Merkel cells mediated by TRPM8 regulates the SA1 mechanical response, particularly at mild fresh temperature, when the nerve conduction is not significantly modified by cold. This is the first description of an active inhibitory process, driven by a TRP channel, during sensory transduction in the skin.