1,720,967 research outputs found
Schwann-like adipose-derived stem cells as a promising therapeutic tool for peripheral nerve regeneration: effects of cholinergic stimulation
Full text linkSchwann-like adipose-derived stem cells and nerve injury: Peripheral nerve injuries (PNIs) are a common clinical problem usually as a consequence of trauma. Despite optimal surgical management, PNI has a lifelong impact on function and wellbeing of the patient. The peripheral nervous system (PNS) has regenerative capability, in contrast
to the central nervous system (CNS), and is dependent on the plasticity of the peripheral glia, Schwann cells (SCs). Despite this regenerative capability, PNI recovery of sensorial and motor function is always incomplete causing pain, cold intolerance, paralysis and impairment of activities of daily living. Therefore, development of innovative approaches enhancing PNS regeneration after injury is of great clinical relevance (Faroni et al., 2015)
Cholinergic effects mediated by M2 muscarinic receptor in human Schwann-like cells induced from adipose mesenchymal stem cells
No full textCholinergic effects mediated by M2 muscarinic receptor in human Schwann-like cells induced from adipose mesenchymal stem cells
Piovesana R.1,2, Faroni A.2, Tata AM1, Reid A.2
1Dept. Biol and Biotech. C. Darwin, University of Rome “Sapienza”, Rome, Italy;
2Blond McIndoe Lab, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK;
Schwann cells (SCs) have an important role in peripheral nerve regeneration but there are several restrictions on their clinical application. Adipose derived stem cells (ASCs) present good properties for cell therapies. When exposed to selective growth factors, they can acquire a SC-like phenotype (dASCs), expressing key SCs markers. Our group has demonstrated in rat model that M2 muscarinic receptor causes in vitro, a reversible arrest of cell proliferation, increasing SCs myelinating phenotype. Human dASCs, as rat dASCs, express muscarinic receptors. In the present work we evaluate if M2 muscarinic receptor activation may contribute to human dASCs proliferation and phenotype. M2 selective activation by selective agonist APE, causes a decreased cell proliferation, modulating the expression of gene involved in the proliferative state (i.e. c-jun and egr2) and neurotrophic factors. Although further analyses are needed to best characterise the role of M2 receptor, these data are the first evidence that its selective activation may have effects also on human dASCs proliferation and may favourite a neuroprotective environment relevant for nerve regeneration
Emerging Roles of Cholinergic Receptors in Schwann Cell Development and Plasticity
Full text linkThe cross talk between neurons and glial cells during development, adulthood, and disease, has been extensively documented. Among the molecules mediating these interactions, neurotransmitters play a relevant role both in myelinating and non-myelinating glial cells, thus resulting as additional candidates regulating the development and physiology of the glial cells. In this review, we summarise the contribution of the main neurotransmitter receptors in the regulation of the morphogenetic events of glial cells, with particular attention paid to the role of acetylcholine receptors in Schwann cell physiology. In particular, the M2 muscarinic receptor influences Schwann cell phenotype and the α7 nicotinic receptor is emerging as influential in the modulation of peripheral nerve regeneration and inflammation. This new evidence significantly improves our knowledge of Schwann cell development and function and may contribute to identifying interesting new targets to support the activity of these cells in pathological conditions
Functional Characterization of Muscarinic Receptors in Human Schwann Cells
Full text linkFunctional characterization of muscarinic cholinergic receptors in myelinating glial cells has been well described both in central and peripheral nervous system. Rat Schwann cells (SCs) express different muscarinic receptor subtypes with the prevalence of the M2 subtype. The selective stimulation of this receptor subtype inhibits SC proliferation, improving their differentiation towards myelinating phenotype. In this work, we describe for the first time that human SCs are cholinoceptive as they express several muscarinic receptor subtypes and, as for rat SCs, M2 receptor is one of the most abundant. Human SCs, isolated from adult nerves, were cultured in vitro and stimulated with M2 muscarinic agonist arecaidine propargyl ester (APE). Similarly to that observed in rat, M2 receptor activation causes a decreased cell proliferation and promotes SC differentiation as suggested by increased Egr2 expression with an improved spindle-like shape cell morphology. Conversely, the nonselective stimulation of muscarinic receptors appears to promote cell proliferation with a reduction of SC average cell diameter. The data obtained demonstrate that human Schwann cells are cholinoceptive and that human cultured Schwann cells may represent an interesting tool to understand their physiology and increase the knowledge on how the cholinergic stimulation may contribute to address human SC development in normal and pathological conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Analysis of Signal Transduction Pathways Downstream M2 Receptor Activation: Effects on Schwann Cell Migration and Morphology
Full text linkBackground: Schwann cells (SCs) express cholinergic receptors, suggesting a role of cholinergic signaling in the control of SC proliferation, differentiation and/or myelination. Our previous studies largely demonstrated that the pharmacological activation of the M2 muscarinic receptor subtype caused an inhibition of cell proliferation and promoted the expression of pro-myelinating differentiation genes. In order to elucidate the molecular signaling activated downstream the M2 receptor activation, in the present study we investigated the signal transduction pathways activated by the M2 orthosteric agonist arecaidine propargyl ester (APE) in SCs. Methods: Using Western blot we analyzed some components of the noncanonical pathways involving β1-arrestin and PI3K/AKT/mTORC1 signaling. A wound healing assay was used to evaluate SC migration. Results: Our results demonstrated that M2 receptor activation negatively modulated the PI3K/Akt/mTORC1 axis, possibly through β1-arrestin downregulation. The involvement of the mTORC1 complex was also supported by the decreased expression of its specific target p-p70 S6KThr389. Then, we also analyzed the expression of p-AMPKαthr172, a negative regulator of myelination that resulted in reduced levels after M2 agonist treatment. The analysis of cell migration and morphology allowed us to demonstrate that M2 receptor activation caused an arrest of SC migration and modified cell morphology probably by the modulation of β1-arrestin/cofilin-1 and PKCα expression, respectively. Conclusions: The data obtained demonstrated that M2 receptor activation in addition to the canonical Gi protein-coupled pathway modulates noncanonical pathways involving the mTORC1 complex and other kinases whose activation may contribute to the inhibition of SC proliferation and migration and address SC differentiation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Notch Signal Mediates the Cross-Interaction between M2 Muscarinic Acetylcholine Receptor and Neuregulin/ErbB Pathway: Effects on Schwann Cell Proliferation
Full text linkThe cross-talk between axon and glial cells during development and in adulthood is mediated by several molecules. Among them are neurotransmitters and their receptors, which are involved in the control of myelinating and non-myelinating glial cell development and physiology. Our previous studies largely demonstrate the functional expression of cholinergic muscarinic receptors in Schwann cells. In particular, the M2 muscarinic receptor subtype, the most abundant cholinergic receptor expressed in Schwann cells, inhibits cell proliferation downregulating proteins expressed in the immature phenotype and triggers promyelinating differentiation genes. In this study, we analysed the in vitro modulation of the Neuregulin-1 (NRG1)/erbB pathway, mediated by the M2 receptor activation, through the selective agonist arecaidine propargyl ester (APE). M2 agonist treatment significantly downregulates NRG1 and erbB receptors expression, both at transcriptional and protein level, and causes the internalization and intracellular accumulation of the erbB2 receptor. Additionally, starting from our previous results concerning the negative modulation of Notch-active fragment NICD by M2 receptor activation, in this work, we clearly demonstrate that the M2 receptor subtype inhibits erbB2 receptors by Notch-1/NICD downregulation. Our data, together with our previous results, demonstrate the existence of a cross-interaction between the M2 receptor and NRG1/erbB pathway-Notch1 mediated, and that it is responsible for the modulation of Schwann cell proliferation/differentiation
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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