Collagène XVI, Cthrc1, FHF1 et Coronine 1 (nouveaux acteurs du cytosquelette et de la matrice extracellulaire dans le système somatosensoriel de souris)

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Le syndrome d’Ehlers-Danlos: l’architecture matricielle en question

Le syndrome d’Ehlers-Danlos constitue un groupe hétérogène de maladies génétiques du tissu conjonctif. Il est caractérisé par une peau hyper-extensible, des articulations anormalement mobiles et des vaisseaux fragiles. Les anomalies moléculaires responsables de cette maladie portent souvent sur les collagènes et les enzymes assurant leur maturation. La forme classique du syndrome, qui sera principalement discutée dans cet article, est majoritairement due à des mutations du collagène V, un collagène fibrillaire présent en petite quantité dans les tissus affectés. Cependant, des anomalies moléculaires du collagène I ou de la ténascine peuvent aussi être responsables de ce syndrome. De plus, chez la souris, l’invalidation de gènes codant pour d’autres molécules matricielles (SPARC, thrombospondine, petits protéoglycanes riches en leucine) conduit à des phénotypes mimant ce syndrome et suggère que ces molécules pourraient donc être impliquées. Comme les anomalies du collagène V restent à ce jour principalement responsables de cette affection, nous discuterons son rôle physiologique à la lumière des observations cliniques et fondamentales. Nous tenterons de comprendre comment le collagène V interagit avec les autres molécules pour déterminer les caractéristiques tissulaires.Ehlers-Danlos syndrome (EDS) is a heterogeneous heritable connective tissue disorder characterized by hyperextensible skin, hypermobile joints and fragile vessels. The molecular causes of this disorder are often, although not strictly, related to collagens and to the enzymes that process these proteins. The classical form of the syndrome, which will be principally discussed in this review, can be due to mutations on collagen V, a fibrillar collagen present in small amounts in affected tissues. However, collagen I and tenascin have also been demonstrated to be involved in the same type of EDS. Moreover gene disruption of several other matrix molecules (thrombospondin, SPARC, small leucine rich proteoglycans...) in mice, lead to phenotypes that mimic EDS and these molecules have thus emerged as new players. As collagen V remains the prime candidate, we discuss, based on fundamental and clinical observations, its physiological role. We also explore its potential interactions with other matrix molecules to determine tissue properties

Development of a Functional Skin Matrix Requires Deposition of Collagen V Heterotrimers

Collagen V is a minor component of the heterotypic I/III/V collagen fibrils and the defective product in most cases of classical Ehlers Danlos syndrome (EDS). The present study was undertaken to elucidate the impact of collagen V mutations on skin development, the most severely affected EDS tissues, using mice harboring a targeted deletion of the α2(V) collagen gene (Col5a2). Contrary to the original report, our studies indicate that the Col5a2 deletion (a.k.a. the pN allele) represents a functionally null mutation that affects matrix assembly through a complex sequence of events. First the mutation impairs assembly and/or secretion of the α1(V)(2)α2(V) heterotrimer with the result that the α1(V) homotrimer is the predominant species deposited into the matrix. Second, the α1(V) homotrimer is excluded from incorporation into the heterotypic collagen fibrils and this in turn severely impairs matrix organization. Third, the mutant matrix stimulates a compensatory loop by the α1(V) collagen gene that leads to additional deposition of α1(V) homotrimers. These data therefore underscore the importance of the collagen V heterotrimer in dermal fibrillogenesis. Furthermore, reduced thickness of the basement membranes underlying the epidermis and increased apoptosis of the stromal fibroblasts in pN/pN skin strongly indicate additional roles of collagen V in the development of a functional skin matrix

Analyse des risques psychosociaux et de la qualité de vie au travail. Diagnostic et préconisations (unité IATE)

il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : ACTIVITY_REPORTAnalyse des risques psychosociaux et de la qualité de vie au travail. Diagnostic et préconisations (unité IATE

CaMKK-CaMK1a, a new post-traumatic signalling pathway induced in mouse somatosensory neurons.

Neurons innervating peripheral tissues display complex responses to peripheral nerve injury. These include the activation and suppression of a variety of signalling pathways that together influence regenerative growth and result in more or less successful functional recovery. However, these responses can be offset by pathological consequences including neuropathic pain. Calcium signalling plays a major role in the different steps occurring after nerve damage. As part of our studies to unravel the roles of injury-induced molecular changes in dorsal root ganglia (DRG) neurons during their regeneration, we show that the calcium calmodulin kinase CaMK1a is markedly induced in mouse DRG neurons in several models of mechanical peripheral nerve injury, but not by inflammation. Intrathecal injection of NRTN or GDNF significantly prevents the post-traumatic induction of CaMK1a suggesting that interruption of target derived factors might be a starter signal in this de novo induction. Inhibition of CaMK signalling in injured DRG neurons by pharmacological means or treatment with CaMK1a siRNA resulted in decreased velocity of neurite growth in vitro. Altogether, the results suggest that CaMK1a induction is part of the intrinsic regenerative response of DRG neurons to peripheral nerve injury, and is thus a potential target for therapeutic intervention to improve peripheral nerve regeneration

Martinique Crinkled Retinal Pigment Epitheliopathy

International audiencePURPOSE:To reappraise the autosomal dominant Martinique crinkled retinal pigment epitheliopathy (MCRPE) in light of the knowledge of its associated mutated gene mitogen-activated protein kinase-activated protein kinase 3 (MAPKAPK3), an actor in the p38 mitogen-activated protein kinase pathway.DESIGN:Clinical and molecular study.PARTICIPANTS:A total of 45 patients from 3 generations belonging to a family originating from Martinique with an autosomal dominant MCRPE were examined.METHODS:Best-corrected visual acuity, fundus photographs, and spectral-domain optical coherence tomography (SD OCT) of all clinically affected patients and carriers for the causal mutation were reviewed at the initial visit and 4 years later for 10 of them. Histologic retinal lesions of Mapkapk3(-/-) mice were compared with those of the human disease.MAIN OUTCOME MEASURES:The MCRPE natural history in view of MAPKAPK3 function and Mapkapk3(-/-) mouse retinal lesions.RESULTS:Eighteen patients had the c.518T>C mutation. One heterozygous woman aged 20 years was asymptomatic with normal fundus and SD OCT (stage 0). All c.518T>C heterozygous patients older than 30 years of age had the characteristic dried-out soil fundus pattern (stages 1 and 2). Complications (stage 3) were observed in 7 cases, including polypoidal choroidal vasculopathy (PCV) and macular fibrosis or atrophy. One patient was homozygous and had a form with severe Bruch's membrane (BM) thickening and macular exudation with a dried-out soil pattern in the peripheral retina. The oldest heterozygous patient, who was legally blind, had peripheral nummular pigmentary changes (stage 4). After 4 years, visual acuity was unchanged in 6 of 10 patients. The dried-out soil elementary lesions radically enlarged in patients with a preferential macular extension and confluence. These findings are in line with the progressive thickening of BM noted with age in the mouse model. During follow-up, there was no occurrence of PCV.CONCLUSIONS:MCRPE is an autosomal dominant, fully penetrant retinal dystrophy with a preclinical stage, an onset after the age of 30 years, and a preserved visual acuity until occurrence of macular complications. The natural history of MCRPE is in relation to the role of MAPKAPK3 in BM modeling, vascular endothelial growth factor activity, retinal pigment epithelial responses to aging, and oxidative stress

Perturbation of the CaMKK-CaMK1a pathway reduces neurite growth velocity of injured DRG neurons <i>in vitro</i>.

<p>(<b>A</b>). Phase-contrast illustrative images at 0, 8 and 24 hours after plating of sensory neurons dissected from naïve animals (upper panels) or from mice having undergone a sciatic nerve axotomy 3 days before (lower panels). Scale bar  = 100 µm. Note that after 24 h, sensory neurons from controls exhibit an arborized growth while many axotomized neurons exhibit an elongated growth. The graph on the right illustrates the growth speed of neurons in both conditions. In controls, the arborized neurons extend neurites at a velocity of 24.92 µm/h+/−1.96, while axotomized elongated neurons extend neurites at a velocity of 54.7+/−2.2 µm/h, confirming previous published studies. (<b>B</b>). Quantification of the neurite growth velocity of axotomized elongated neurons put in culture 3 days after a sciatic nerve section during 24 hours without (dark grey column) or with (light grey column) treatment with the CaMKK inhibitor STO-609. Untreated axotomized elongated neurons normally extend neurites at a velocity of 54.7+/−2.2 µm/h. With STO-609 (0.5 µg/µl) treatment, we observed a 25% reduction of the growth speed which drops to 40.8+/−2,6 µm/h. (<b>C</b>). Quantification of the effect of Control or CaMK1a siRNA on the velocity of neurite outgrowth of axotomized elongated neurons. Mice were given intrathecal injections of CaMK1a siRNA or control non-targeting siRNA in transfection agent containing dextran- tetramethylrhodamine as an indicator of transfection. The graph on the left show QRT-PCRs revealing a 46% reduction of CamK1a expression specifically in neurons injected with CamK1a siRNA compared to control siRNA. The neurite growth velocities of axotomized dextran+ and dextran- neurons were evaluated and reported on the graph on the right. CaMK1a siRNA transfection reduced DRG neurite outgrowth from 55+/−2,48 to 30+/−2,47 µm/h while control siRNA had no effect.</p

CaMK1a is preferentially induced in large diameter Ret+ neurons after axotomy.

<p>(<b>A–D</b>). Combined CaMK1a immunohistochemistry and retrograde labelling with Fluorogold (FG) on L4–L5 DRG sections three days post-axotomy of the sciatic nerve. FG was applied at the cut nerve stump and specifically labels axotomized neurons. (<b>E</b>). Counts on DRG sections show that 74+/−2% of CaMK1a+ neurons are FG+. (<b>F</b>). Cell soma size distribution of CaMK1a+ neurons in DRG after sciatic nerve axotomy. (<b>G–J</b>). Double-immunofluorescent staining for CaMK1a and NF-200 on sections of L4–L5 DRG three days post-axotomy. (<b>K–N</b>). Double-immunofluorescent staining for CaMK1a and Ret on DRG sections three days post-axotomy shows numerous co-labelled neurons for both proteins. (<b>O</b>). Counts of CamK1a+NF200+ double-labeled cell reveals that about 50% of CaMK1a-positive neurons are NF200+. (<b>P</b>). Size repartition of CamK1a+Ret+ double-labeled cells showing that the vast majority of CaMK1a-positive neurons with medium-large cell soma diameter also express Ret.</p

Primer sequences used for PCR products intended to generate In Situ Hybridization Probes (1) or for Real-Time Polymerase Chain Reaction (2).

<p>Primer sequences used for PCR products intended to generate In Situ Hybridization Probes (1) or for Real-Time Polymerase Chain Reaction (2).</p