Vector uncoating limits adeno-associated viral vector-mediated transduction of human dendritic cells and vector immunogenicity.

AAV vectors poorly transduce Dendritic cells (DC), a feature invoked to explain AAV's low immunogenicity. However, the reason for this non-permissiveness remained elusive. Here, we performed an in-depth analysis using human monocyte-derived immature DC (iDC) as model.

Evolution of gene neighborhoods within reconciled phylogenies.

Motivation: Most models of genome evolution integrating gene duplications, losses and chromosomal rearrangements are computationally intract able, even when comparing only two genomes. This prevents large-scale studies that consider different types of genome structural variations.

Results: We define an 'adjacency phylogenetic tree' that describes the evolution of an adjacency, a neighborhood relation between two genes, by speciation, duplication or loss of one or both genes, and rearrangement.

Eccentric stimulation reveals an involvement of FGF6 in muscle resistance to mechanical stress.

The objective of this report was to analyse a potential role for FGF6 in muscle resistance to mechanical stress. Normal or regenerating muscles of FGF6 (-/-) mice versus wild-type mice were submitted to different protocols of damaging eccentric contractions (eccentric electrostimulation and intermittent downhill exercise). Then muscular structural properties were analysed by histological and immunochemistry techniques to evaluate the post-injury muscle recovery; their muscle contractile parameters (maximal tetanic force, kinetics properties and fatigue resistance) were assessed.

The Xenopus MEF2 gene family: evidence of a role for XMEF2C in larval tendon development.

MEF2 transcription factors are well-established regulators of muscle development. In this report, we describe the cloning of multiple splicing isoforms of the XMEF2A and XMEF2C encoding genes, differentially expressed during Xenopus development. Using whole-mount in situ hybridization, we found that the accumulation of XMEF2C mRNA in the tadpole stages was restricted to intersomitic regions and to the peripheral edges of hypaxial and cranial muscle masses in contrast to XMEF2A and XMEF2D, characterized by a continuous muscle cell expression.

Exercise-induced modulation of calcineurin activity parallels the time course of myofibre transitions.

This study establishes a causal link between the limitation of myofibre transitions and modulation of calcineurin activity, during different exercise paradigms. We have designed a new swimming-based training protocol in order to draw a comparison between a high frequency and amplitude exercise (swimming) and low frequency and amplitude exercise (running). We initially analysed the time course of muscle adaptations to a 6- or 12-week swimming- or running-based training exercise program, on two muscles of the mouse calf, the slow-twitch soleus and the fast-twitch plantaris.

Regular exercise prolongs survival in a type 2 spinal muscular atrophy model mouse.

Several studies indicate that physical exercise is likely to be neuroprotective, even in the case of neuromuscular disease. In the present work, we evaluated the efficiency of running-based training on type 2 spinal muscular atrophy (SMA)-like mice. The model used in this study is an SMN (survival motor neuron)-null mouse carrying one copy of a transgene of human SMN2.

Effects of eccentric treadmill running on mouse soleus: degeneration/regeneration studied with Myf-5 and MyoD probes.

Aim: The aim of this report is to show that eccentric exercise under well-controlled conditions is an alternative model, to chemical and mechanical analyses, and analyse the process of degeneration/regeneration in mouse soleus.

Methods: For this, mice were submitted to a single bout of eccentric exercise on a treadmill down a 14 degrees decline for 150 min and the soleus muscle was analysed at different times following exercise by histology and in situ hybridization in comparison with cardiotoxin-injured muscles.

Results: We analyse the regenerative process by detection of the accumulation of transcripts coding for the two myogenic regulatory factors, Myf-5 and MyoD, which are good markers of the activated satellite cells.

Specific activation of the acetylcholine receptor subunit genes by MyoD family proteins.

Whether the myogenic regulatory factors (MRFs) of the MyoD family can discriminate among the muscle gene targets for the proper and reproducible formation of skeletal muscle is a recurrent question. We have previously shown that, in Xenopus laevis, myogenin specifically transactivated muscle structural genes in vivo. In the present study, we used the Xenopus model to examine the role of XMyoD, XMyf5, and XMRF4 for the transactivation of the (nicotinic acetylcholine receptor) nAChR genes in vivo.

Expression and neural control of follistatin versus myostatin genes during regeneration of mouse soleus.

Follistatin and myostatin are two secreted proteins involved in the control of muscle mass during development. These two proteins have opposite effects on muscle growth, as documented by genetic models. The aims of this work were to analyze in mouse, by using in situ hybridization, the spatial and temporal expression patterns of follistatin and myostatin mRNAs during soleus regeneration after cardiotoxin injury, and to investigate the influence of innervation on the accumulation of these two transcripts.

[High-performance society and doping].

Doping is not limited to high-level athletes. Likewise it is not limited to the field of sports activities. The doping phenomenon observed in sports actually reveals an underlying question concerning the notion of sports itself, and more widely, the society's conception of sports.

Two myogenin-related genes are differentially expressed in Xenopus laevis myogenesis and differ in their ability to transactivate muscle structural genes.

Among the myogenic regulatory factors, myogenin is a transcriptional activator situated at a crucial position for terminal differentiation in muscle development. It is unclear at present whether myogenin exhibits unique specificities to transactivate late muscular markers. During Xenopus development, the accumulation of myogenin mRNA is restricted to secondary myogenesis, at the onset of the appearance of adult isoforms of beta-tropomyosin and myosin heavy chain.

Expression and neural control of myogenic regulatory factor genes during regeneration of mouse soleus.

Given the importance of the myogenic regulatory factors (MRFs) for myoblast differentiation during development, the aims of this work were to clarify the spatial and temporal expression pattern of the four MRF mRNAs during soleus regeneration in mouse after cardiotoxin injury, using in situ hybridization, and to investigate the influence of innervation on the expression of each MRF during a complete degeneration/regeneration process. For this, we performed cardiotoxin injury-induced regeneration experiments on denervated soleus muscle. Myf-5, MyoD, and MRF4 mRNAs were detected in satellite cell-derived myoblasts in the first stages of muscle regeneration analyzed (2--3 days P-I).

Neural and hormonal control of expression of myogenic regulatory factor genes during regeneration of Xenopus fast muscles: myogenin and MRF4 mRNA accumulation are neurally regulated oppositely.

With the aim to investigate the influence of both innervation and thyroid hormone, on the expression of the MRFs during muscle regeneration, we performed cardiotoxin injury-induced regeneration experiments on fast muscles of adult Xenopus laevis subjected to different experimental conditions, including denervation and T3 treatment, and analyzed the accumulation of the four myogenic regulatory factors (MRFs) using RT-PCR and in situ hybridization. We show here that manipulation of hormone levels or innervation resulted in differential alterations of MRF expression. Denervation and T3 treatment transiently down-regulated Myf-5 mRNA levels at the beginning of the regeneration process.

Expression of the proteoglycan SPOCK during mouse embryo development.

SPOCK is a modular proteoglycan, with homology with proteins involved in cell adhesion processes and neurogenesis. We have previously shown that SPOCK transcripts predominate in the adult mouse brain. Here, we report its expression during mouse embryonic development by in situ hybridization, and immunocytochemistry.

Long-term denervation modulates differentially the accumulation of myogenin and MRF4 mRNA in adult Xenopus muscle.

In adult Xenopus laevis, we analyzed, using reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization, the influence of long-term muscle denervation on the accumulation of MRF4 and myogenin transcripts. The brachial muscle was denervated by cutting the brachial nerve and was examined after 4 months. MRF4 mRNA levels decreased about two-fold in denervated muscle as compared with contralateral muscle.

Expression of myogenic regulatory factors during muscle development of Xenopus: myogenin mRNA accumulation is limited strictly to secondary myogenesis.

To clarify the acquisition of the adult muscle pattern in Xenopus laevis, in situ hybridization and reverse transcriptase-polymerase chain reaction were used to correlate the time course of gene expression for myogenic regulatory factors (Myf-5, MyoD, and myogenin) with the expression of contractile protein (myosin heavy chain; MHC) genes during hindlimb formation compared with their expression in dorsal body muscles. After the precocious expression of Myf-5 and MyoD mRNA in limb bud (stage 50), myogenin mRNA strongly accumulated later at paddle stages (stages 52/53) concomitantly with the accumulation of both the larval and the adult MHC mRNAs. In dorsal body muscles, as early as stage 52, myogenin transcripts accumulated in a few small, secondary myofibers expressing the adult MHC mRNA that were located along the dorsomedial edge, but they were never detected in the large, primary myofibers of the body expressing the larval MHC mRNA.

Localization of Myf-5, MRF4 and alpha cardiac actin mRNAs in regenerating Xenopus skeletal muscle.

We have analysed the spatial and temporal expression patterns of Myf-5, MRF4 and alpha cardiac actin mRNAs during muscle regeneration following cardiotoxin injury in adult Xenopus laevis using in situ hybridization. Myf-5 transcripts began to be detected in the activated satellite cells as early as the beginning of the regeneration process, then dramatically decreased in young plurinucleated myotubes. MRF4 mRNA was detected later, just before the young myotube stage, and was strongly expressed during the different stages of the maturation of myotubes.

Analysis of muscle adaptations to terrestrial stepping in the Urodelan amphibian Pleurodeles waltlii.

The changes of myosin isoform pattern and of its associated light chains in relation to the myosin ATPase profile were analysed in different muscles of the hypothyroidian amphibian Pleurodeles waltlii submitted to terrestrial stepping, using electrophoretic and histochemical techniques. These changes were specific to the muscle type but appeared globally characterized by a type-IIB to type-IIA/I fibre transition associated with a transition from fast to intermediate and/or slow myosin isoforms. These results are similar to the effects of endurance training on locomotor muscles of mammals.

Analysis of MyoD, myogenin, and muscle-specific gene mRNAs in regenerating Xenopus skeletal muscle.

We have analyzed in adult Xenopus laevis, using in situ hybridization, the spatial and temporal expression patterns of MyoD, myogenin, and alpha-skeletal actin and fast myosin heavy chain mRNAs during muscle regeneration following cardiotoxin injury. MyoD transcripts could be detected in the satellite cells as early as the first stage of regeneration and were expressed persistently throughout the regeneration process. Myogenin mRNAs were transiently expressed in forming myotubes.

Myosin isoforms and their light chains from the ventricular muscle of the urodelan amphibian Pleurodeles waltlii: comparison with myosin from skeletal muscles.

Myosin extracted from ventricular muscle of the urodelan amphibian Pleurodeles waltlii was analyzed in comparison with myosin extracted from skeletal muscles by native, one-dimensional SDS gel electrophoresis and two-dimensional gel electrophoresis. Two myosin isoforms were detected in ventricular muscle using pyrophosphate gel electrophoresis. These isomyosins contained two types of light chain subunits, LC1v and LC2v.

Cloning and expression of a thyroid hormone receptor alpha 1 in the perennibranchiate amphibian Proteus anguinus.

We demonstrated the presence of thyroid hormone receptor alpha mRNAs in tissues of the perennibranchiate amphibian Proteus anguinus, which is insensitive to thyroid hormone. From P. anguinus muscle we cloned and sequenced the 3' coding and untranslated region of a cDNA corresponding to a thyroid hormone receptor alpha 1.

The emergence of an adult muscle phenotype in urodelan amphibians: an immunohistochemical study.

Electrophoretic techniques adapted for the analysis of muscles of lower invertebrates reveal four myosin heavy chain isoforms in the dorsalis trunci of Pleurodeles waltlii: two fast (MHC-IIA, MHC-IIB), and one slow (MHC-I) in the adult and one isoform (MHC-La) in the larvae. Polyclonal antibodies were prepared against the larval (anti-MHC-La) and one of the fast myosin (MHC-IIA) isoforms and their specificity was confirmed by western blot analysis. An immunohistochemical analysis was then carried out on frozen sections of the dorsalis trunci of P.

Morphological and biochemical analysis of regeneration after cardiotoxin injury of Xenopus laevis fast muscles.

The anterior brachial muscle of Xenopus laevis forelimb was characterized as a fast-type muscle composed of type II fibers exclusively. Larval and adult muscles showed three distinct isomyosins composed by two different heavy chains, HCl and HCf, respectively, associated with the same fast light chains. Muscle regeneration was examined after degeneration of the myofibers by injection of cardiotoxin, a snake toxin.

Pituitary-thyroid axis controls the final differentiation of the dorsal skeletal muscle in urodelan amphibians.

A histoenzymological study of the ATPase activity of myosin in the dorsal axis muscle (dorsalis trunci) was carried out on two species of urodelan amphibians: Pleurodeles waltlii, a euthyroid species with spontaneous metamorphosis and Ambystoma mexicanum, a neotenic hypothyroid species. P. waltlii and A.

A new approach of urodele amphibian limb regeneration: study of myosin isoforms and their control by thyroid hormone.

In P. waltlii, an urodele amphibian species which undergoes spontaneous metamorphosis, study of native myosin in pyrophosphate gels at various stages of normal development demonstrates a complete larval to fast myosin isoforms transition, which occurs more precociously in forelimb muscles than in the dorsal and ventral muscles. In the neotenic species A.