1,720,965 research outputs found
Rejuvenating muscle stem cells with the glutathione system
No full text: Aging results from the combination of complex processes still largely undefined. In this issue, Benjamin et al. use multiomic analysis to reveal a causative role of altered glutathione (GSH) synthesis and metabolism in age-dependent muscle stem cell (MuSC) dysfunction, casting light on novel mechanisms regulating stem cell function and on therapeutic approaches to improve defective regeneration in the aged muscle
Study and modulation of dystrophic microenvironment to improve stem cell-mediated therapy
No full textDuchenne muscular dystrophy (DMD) is a degenerative disease largely refractory to different therapeutic approaches. Cell-based therapies are promising methods for treating DMD but stalled by a limited impact of transplanted stem cells on the long term muscle cell replacement. Among factors that might interfere with therapeutic approaches, the dystrophic environment could represent an important determinant. Thus, a better understanding of pathogenic mechanisms affecting muscle niche should prove useful for producing new adjuvant treatments. Interleukin 6 (IL-6) is a potential candidate that might contribute to sustain a hostile degenerating environment in dystrophic muscle. In the present study we provided evidences that IL-6 can perturb muscle milieu being causally linked to the pathogenesis of muscular dystrophy. We reported that increased circulating levels of IL-6 alone are sufficient to exacerbate the dystrophic muscle phenotype, increasing muscle necrosis, inflammation and cycles of regeneration/degeneration leading to the exhaustion of the muscle stem cell pool. Moreover, IL-6 is able to enhance ROS production and to impinge the anti-oxidant response during the progression of pathology, closely approximating the severity of human disease. Otherwise, the over-expression in dystrophic muscle of a positive anabolic factor, namely mIGF-1, contributes to ameliorate muscle niche by preventing the establishment of chronic inflammation and pro-oxidant conditions. Forced expression of mIGF-1 in mdx mice is able to confer robustness to dystrophic muscle enhancing differentiation and maturation processes, also preserving muscle functionality. This results in the establishment of a qualitative environment sustaining both endogenous and transplanted stem cells, since we reported that a mesoangioblast-based stem cell therapy have a major impact on mdx/mIGF-1 muscles respect to mdx ones. Thus, the positive modulation of dystrophic muscle niche exerted by mIGF-1 has intriguing implications in the field of stem cell treatments for DMD
MicroRNA signature in mdx dystrophic mice overexpressing mIGF-1 in Abstracts of the XII annual meeting of the Interuniversity Institute of Myology | Reggio Emilia, Italy, October 1-4, 2015
No full textDuchenne muscular dystrophy (DMD) is a genetic disease in which loss of functional dystrophin protein results in progressive skeletal muscle degeneration. Although the genetic defect is widely known, the mechanisms by which the absence of dystrophin leads to the complex pathophisiology of the disease is not completely understood. MiRNAs are small non coding RNA that are important regulatory elements for muscle development and function [1]. Altered levels of specific miRNAs were found in several muscular disorders, including DMD [2, 3]. In particular it has been identified a specific DMD-signature miRNAs that may serve as a marker for therapeutic purposes [4]. Moreover, in a recent work it has been defined a specific group of miRNAs strictly correlated to dystrophin levels and whose deregulated expression could explain several pathogenetic features of DMD [5]. Previously we have demonstrated that the local expression of mIGF-1 in mdx mice ameliorates the dystrophic phenotype reducing myonecrosis and upregulating survival pathways such as AKT pathway [6]. In this work, we show that a specific group of miRNAs, dystrophin-indipendent, are modulated by mIGF-1 expression. In particular, local expression of mIGF-1 promotes the modulation of miR-206 and miR-24 as well as muscle specific genes associated with maturation of regenerating muscle fibers and differentiation. These results indicates that local overexpression of the anabolic factor mIGF-1 in mdx mice ameliorates the dystrophic microenviroment modulating the expression of a specific group of miRNAs and inducing a partial rescue of the characteristic DMD-signature
An overview about the biology of skeletal muscle satellite cells
Get PDFThe peculiar ability of skeletal muscle tissue to operate adaptive changes during post-natal de-velopment and adulthood has been associated with the existence of adult somatic stem cells. Satellite cells, occupying an exclusive niche within the adult muscle tissue, are considered bona fide stem cells with both stem-like properties and myogenic activities. Indeed, satellite cells retain the capability to both maintain the quiescence in uninjured muscles and to be promptly activated in response to growth or re-generative signals, re-engaging the cell cycle. Activated cells can undergo myogenic differentiation or self-renewal moving back to the quiescent state. Satellite cells behavior and their fate decision are finely controlled by mechanisms involving both cell-autonomous and external stimuli. Alterations in these regu-latory networks profoundly affect muscle homeostasis and the dynamic response to tissue damage, con-tributing to the decline of skeletal muscle that occurs under physio-pathologic conditions. Although the clear myogenic activity of satellite cells has been described and their pivotal role in muscle growth and regeneration has been reported, a comprehensive picture of inter-related mechanisms guiding muscle stem cell activity has still to be defined. Here, we reviewed the main regulatory networks determining satellite cell behavior. In particular, we focused on genetic and epigenetic mechanisms underlining satel-lite cell maintenance and commitment. Besides intrinsic regulations, we reported current evidences about the influence of environmental stimuli, derived from other cell populations within muscle tissue, on satel-lite cell biology
The physiopathologic interplay between stem cells and tissue niche in muscle regeneration and the role of IL-6 on muscle homeostasis and diseases
No full textSkeletal muscle is a complex, dynamic tissue characterized by an elevated plasticity. Although the adult muscle is mainly composed of multinucleated fibers with post mitotic nuclei, it retains a remarkable ability to regenerate in response to traumatic events. The regenerative potential of the adult skeletal muscle relies in the activity of satellite cells, mononucleated cells residing within the muscle in intimate association with myofibers. Satellite cells normally remain quiescent in their sublaminar position, sporadically entering the cell cycle to guarantee an efficient cellular turnover, by fusing with pre-existing myofibers, and to maintain the stem cell pool. However, after muscle injury satellite cells undergo an extensive increase of their activity in response to environmental stimuli, thereby participating to the regeneration of a functional muscle tissue. Nevertheless, regeneration is affected in several pathologic conditions and by a wide range of environmental signals that are highly variable, not only through time, but also depending on the physiological or pathological conditions of the musculature. Among these factors, the interleukin-6 (IL-6) plays a critical physiopathologic role on muscle homeostasis and diseases. The basis of muscle regeneration and the impact of IL-6 on the physiopathology of skeletal muscle will be discussed
Insights into the pathogenic secondary symptoms caused by the primary loss of dystrophin
Get PDFDuchenne muscular dystrophy (DMD) is an X-linked genetic disease in which the dystrophin gene is mutated, resulting in dysfunctional dystrophin protein. Without dystrophin, the dystrophin-glycoprotein complex (DGC) is unstable, leading to an increase in muscle damage. Moreover, the imbalance between muscle damage and repair leads to a chronic inflammatory response and an increase in the amount of fibrosis over time. The absence of dystrophin at the sarcolemma also delocalizes and downregulates nitric oxide synthase (nNOS) and alters enzymatic antioxidant responses, leading to an increase in oxidative stress. In this review, we analyze the pathogenic role of both inflammation and oxidative stress in muscular dystrophy
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
MicroRNAs modulated by local mIGF-1 expression in mdx dystrophic mice
Get PDFDuchenne muscular dystrophy (DMD) is a X-linked genetic disease in which the absence of dystrophin leads to progressive lethal skeletal muscle degeneration.It has been demonstrated that among genes which are important for proper muscle development and function, micro-RNAs (miRNAs) play a crucial role. Moreover, altered levels of miRNAs were found in several muscular disorders, including DMD. A specific group of miRNAs, whose expression depends on dystrophin levels and whose deregulation explains several DMD pathogenetic traits, has been identified. Here, we addressed whether the anabolic activity of mIGF-1 on dystrophic muscle is associated with modulation of microRNAs expression.We demonstrated that some microRNAs are strictly linked to the dystrophin expression and are not modulated by mIGF-1 expression. In contrast, local expression of mIGF-1 promotes the modulation of other microRNAs, such as miR-206 and mir-24, along with the modulation of muscle specific genes, which are associated with maturation of regenerating fibers and with the stabilization of the differentiated muscle phenotype.These data suggest that mIGF-1, modifying the expression of some of the active players of muscle homeostasis, is able, even in absence of dystrophin expression, to activate circuitries that confer robustness to dystrophic muscle
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