Increased Risk of Aortic Dissection with Perlecan Deficiency

Perlecan (HSPG2), a basement membrane-type heparan sulfate proteoglycan, has been implicated in the development of aortic tissue. However, its role in the development and maintenance of the aortic wall remains unknown. Perlecan-deficient mice (Hspg2−/−-Tg: Perl KO) have been found to show a high frequency (15–35%) of aortic dissection (AD). Herein, an analysis of the aortic wall of Perl KO mice revealed that perlecan deficiency caused thinner and partially torn elastic lamina. Compared to the control aortic tissue, perlecan-deficient aortic tissue showed a significant decrease in desmosine content and an increase in soluble tropoelastin levels, implying the presence of immature elastic fibers in Perl KO mice. Furthermore, the reduced expression of the smooth muscle cell contractile proteins actin and myosin in perlecan-deficient aortic tissue may explain the risk of AD. This study showed that a deficiency in perlecan, which is localized along the elastic lamina and at the interface between elastin and fibrillin-1, increased the risk of AD, largely due to the immaturity of extracellular matrix in the aortic tissue. Overall, we proposed a new model of AD that considers the deficiency of extracellular molecule perlecan as a risk factor

Regulation of fractone heparan sulfate composition in young and aged subventricular zone neurogenic niches

International audienceAbstract Fractones, specialized extracellular matrix structures found in the subventricular zone (SVZ) neurogenic niche, can capture growth factors, such as basic fibroblast growth factor, from the extracellular milieu through a heparin-binding mechanism for neural stem cell presentation, which promotes neurogenesis. During aging, a decline in neurogenesis correlates with a change in the composition of heparan sulfate (HS) within fractones. In this study, we used antibodies that recognize specific short oligosaccharides with varying sulfation to evaluate the HS composition in fractones in young and aged brains. To further understand the conditions that regulate 6-O sulfation levels and its impact on neurogenesis, we used endosulfatase Sulf1 and Sulf2 double knock out (DKO) mice. Fractones in the SVZ of Sulf1/2 DKO mice showed immunoreactivity for the HS epitope, suggesting higher 6-O sulfation. While neurogenesis declined in the aged SVZ of both WT and Sulf1/2 DKO mice, we observed a larger number of neuroblasts in the young and aged SVZ of Sulf1/2 DKO mice. Together, these results show that the removal of 6-O-sulfation in fractones HS by endosulfatases inhibits neurogenesis in the SVZ. Our findings advance the current understanding regarding the extracellular environment that is best suited for neural stem cells to thrive, which is critical for the design of future stem cell therapies

α-1,6-Fucosyltransferase Is Essential for Myogenesis in Zebrafish

Glycosylation is an important mechanism regulating various biological processes, including intercellular signaling and adhesion. α-1,6-fucosyltransferase (Fut8) belongs to a family of enzymes that determine the terminal structure of glycans. Fut8 is widely conserved from Caenorhabditis elegans to humans, and its mutants have been reported in humans, mice, and zebrafish. Although mutants show various symptoms, such as spinal deformity and growth retardation, its effects on skeletal muscles are unknown. We aimed to elucidate the function of Fut8 in skeletal muscle using zebrafish and C2C12 cells for evaluation. We observed that most fut8a morphants died at 2 days post-fertilization (dpf) or in earlier developmental stages even at low concentrations of morpholino oligonucleotides (MOs). Mutant juveniles also had small body sizes, and abnormal myocepta and sarcomere structures, suggesting that Fut8a plays important roles in myogenesis. Moreover, treatment of C2C12 cells with 2-fluorofucose (2FF), a fucosylation inhibitor, during cell differentiation dramatically reduced the expression of myogenic genes, such as Myomaker and other myogenic fusion genes, and inhibited myotube formation. These results indicate that Fut8 is an important factor in myogenesis, and myofusion in particular

Perlecan is required for FGF-2 signaling in the neural stem cell niche

In the adult subventricular zone (neurogenic niche), neural stem cells double-positive for two markers of subsets of neural stem cells in the adult central nervous system, glial fibrillary acidic protein and CD133, lie in proximity to fractones and to blood vessel basement membranes, which contain the heparan sulfate proteoglycan perlecan. Here, we demonstrate that perlecan deficiency reduces the number of both GFAP/CD133-positive neural stem cells in the subventricular zone and new neurons integrating into the olfactory bulb. We also show that FGF-2 treatment induces the expression of cyclin D2 through the activation of the Akt and Erk1/2 pathways and promotes neurosphere formation in vitro. However, in the absence of perlecan, FGF-2 fails to promote neurosphere formation. These results suggest that perlecan is a component of the neurogenic niche that regulates FGF-2 signaling and acts by promoting neural stem cell self-renewal and neurogenesis

Understanding microstructure of the brain by comparison of neurite orientation dispersion and density imaging (NODDI) with transparent mouse brain.

Background\nNeurite orientation dispersion and density imaging (NODDI) is a diffusion magnetic resonance imaging (MRI) technique with the potential to visualize the microstructure of the brain. Revolutionary histological methods to render the mouse brain transparent have recently been developed, but verification of NODDI by these methods has not been reported.\nPurpose\nTo confirm the concordance of NODDI with histology in terms of density and orientation dispersion of neurites of the brain.\nMaterial and Methods\nWhole brain diffusion MRI of a thy-1 yellow fluorescent protein mouse was acquired with a 7-T MRI scanner, after which transparent brain sections were created from the same mouse. NODDI parameters calculated from the MR images, including the intracellular volume fraction (Vic) and the orientation dispersion index (ODI), were compared with histological findings. Neurite density, Vic, and ODI were compared between areas of the anterior commissure and the hippocampus containing crossing fibers (crossing areas) and parallel fibers (parallel areas), and the correlation between fiber density and Vic was assessed.\nResults\nThe ODI was significantly higher in the crossing area compared to the parallel area in both the anterior commissure and the hippocampus (P = 0.0247, P = 0.00022, respectively). Neurite density showed a similar tendency, but was significantly different only in the hippocampus (P = 7.91E−07). There was no significant correlation between neurite density and Vic.\nConclusion\nNODDI was verified by histology for quantification of the orientation dispersion of neurites. These results indicate that the ODI is a suitable index for understanding the microstructure of the brain in vivo

Les missions et objectifs du Réseau recherche de la Société française d’anesthésie et de réanimation

National audienceDepuis une dizaine d’années, la recherche clinique en Anesthésie-Réanimation voit une augmentation du nombre de protocoles développés et de publications, tant au niveau médical que paramédical. Des réseaux très structurés existent à l’étranger et imposent une concurrence importante dans la course à l’innovation, ainsi qu’au déroulement et à la valorisation des protocoles de recherche. La complexification récente de la méthodologie de la recherche clinique rend la professionnalisation et la structuration de la recherche clinique au sein de notre société savante nécessaires. Le Comité Réseau Recherche de la Société française d’anesthésie et de réanimation (SFAR) a pour but de fournir un label qualité à la recherche clinique médicale et paramédicale, grâce à un accompagnement des projets de recherche tout au long du processus : expertise et interaction avec les investigateurs, recrutement des centres, suivi du déroulement des études, aide à la rédaction des articles. Les objectifs sont d’aider les investigateurs à optimiser les chances de financements de projets, d’assurer la faisabilité des travaux et de valoriser scientifiquement les résultats. Pour la SFAR, cette valorisation des travaux de recherche nationaux participe au rayonnement international de notre spécialité

Comment choisir la question de son essai clinique ? Les conseils du Réseau Recherche de la SFAR

National audienceEvery research project begins with a question. As its nature will influence all subsequent steps, including the methodology, the question should be clear and well-defined from the outset. This is therefore a major step in carrying out a research project, which requires expertise and work. It is indeed clinical experience and previous research that lead to a good question. For it to be relevant, it is necessary to master existing literature on the subject, to be open to new ideas, new techniques, new methodologies, imagination and creativity, as well as to pay attention to mentorship and expert advice. This question must meet criteria for feasibility, interest, novelty, ethics, and relevance (the FINER criteria). It should be formulated in a structured way to ensure maximum clarity, for example following the PICOT framework. Therefore, defining the main question of your clinical trial is not just a semantic exercise.Tous les travaux de recherche commencent par une question. Cette question doit être claire et bien définie dès le départ, car sa nature influencera toutes les étapes suivantes, notamment la méthodologie. Il s’agit donc d’une étape majeure dans la réalisation d’un projet de recherche, qui demande de l’expertise et du travail. Une bonne question émerge en effet de l’expérience clinique et des recherches réalisées antérieurement. Elle nécessite pour être pertinente une maîtrise de la littérature existante sur le sujet, une ouverture à de nouvelles idées, de nouvelles techniques, de nouvelles méthodologies, de l’imagination et de la créativité, mais aussi une grande attention aux conseils de ses mentors et des experts établis. Cette question doit répondre à des critères de faisabilité, d’intérêt, de nouveauté, d’éthique et de pertinence (les critères FINER). Elle doit être formulée de manière structurée pour assurer un maximum de clarté, en suivant par exemple le cadre PICOT (pour population, intervention étudiée, contrôle, outcome et timeframe). Choisir et formuler la question principale de son essai clinique n’est donc pas un exercice purement sémantique