Heparanase 2, mutated in urofacial syndrome, mediates peripheral neural development in Xenopus

Urofacial syndrome (UFS; previously Ochoa syndrome) is an autosomal recessive disease characterized by incomplete bladder emptying during micturition. This is associated with a dyssynergia in which the urethral walls contract at the same time as the detrusor smooth muscle in the body of the bladder. UFS is also characterized by an abnormal facial expression upon smiling, and bilateral weakness in the distribution of the facial nerve has been reported. Biallelic mutations in HPSE2 occur in UFS. This gene encodes heparanase 2, a protein which inhibits the activity of heparanase. Here, we demonstrate, for the first time, an in vivo developmental role for heparanase 2. We identified the Xenopus orthologue of heparanase 2 and showed that the protein is localized to the embryonic ventrolateral neural tube where motor neurons arise. Morpholino-induced loss of heparanase 2 caused embryonic skeletal muscle paralysis, and morphant motor neurons had aberrant morphology including less linear paths and less compactly-bundled axons than normal. Biochemical analyses demonstrated that loss of heparanase 2 led to upregulation of fibroblast growth factor 2/phosphorylated extracellular signal-related kinase signalling and to alterations in levels of transcripts encoding neural- and muscle-associated molecules. Thus, a key role of heparanase 2 is to buffer growth factor signalling in motor neuron development. These results shed light on the pathogenic mechanisms underpinning the clinical features of UFS and support the contention that congenital peripheral neuropathy is a key feature of this disorder

The outer limiting membrane (OLM) revisited: clinical implications

PURPOSE: The outer limiting membrane (OLM) is considered to play a role in maintaining the structure of the retina through mechanical strength. However, the observation of junction proteins located at the OLM and its barrier permeability properties may suggest that the OLM may be part of the retinal barrier. MATERIAL AND METHODS: Normal and diabetic rat, monkey, and human retinas were used to analyze junction proteins at the OLM. Proteome analyses were performed using immunohistochemistry on sections and flat-mounted retinas and western blotting on protein extracts obtained from laser microdissection of the photoreceptor layers. Semi-thin and ultrastructure analyses were also reported. RESULTS: In the rat retina, in the subapical region zonula occludens-1 (ZO-1), junction adhesion molecule (JAM), an atypical protein kinase C, is present and the OLM shows dense labeling of occludin, JAM, and ZO-1. The presence of occludin has been confirmed using western blot analysis of the microdissected OLM region. In diabetic rats, occludin expression is decreased and glial cells junctions are dissociated. In the monkey retina, occludin, JAM, and ZO-1 are also found in the OLM. Junction proteins have a specific distribution around cone photoreceptors and Müller glia. Ultrastructural analyses suggest that structures like tight junctions may exist between retinal glial Müller cells and photoreceptors. CONCLUSIONS: In the OLM, heterotypic junctions contain proteins from both adherent and tight junctions. Their structure suggests that tight junctions may exist in the OLM. Occludin is present in the OLM of the rat and monkey retina and it is decreased in diabetes. The OLM should be considered as part of the retinal barrier that can be disrupted in pathological conditions contributing to fluid accumulation in the macula

Human Adult Neurogenesis: Evidence and Remaining Questions

Renewed discussion about whether or not adult neurogenesis exists in the human hippocampus, and the nature and strength of the supporting evidence, has been reignited by two prominently published reports with opposite conclusions. Here, we summarize the state of the field and argue that there is currently no reason to abandon the idea that adult-generated neurons make important functional contributions to neural plasticity and cognition across the human lifespan

Transplantation of canine olfactory ensheathing cells producing chondroitinase ABC promotes chondroitin sulphate proteoglycan digestion and axonal sprouting following spinal cord injury

Olfactory ensheathing cell (OEC) transplantation is a promising strategy for treating spinal cord injury (SCI), as has been demonstrated in experimental SCI models and naturally occurring SCI in dogs. However, the presence of chondroitin sulphate proteoglycans within the extracellular matrix of the glial scar can inhibit efficient axonal repair and limit the therapeutic potential of OECs. Here we have used lentiviral vectors to genetically modify canine OECs to continuously deliver mammalian chondroitinase ABC at the lesion site in order to degrade the inhibitory chondroitin sulphate proteoglycans in a rodent model of spinal cord injury. We demonstrate that these chondroitinase producing canine OECs survived at 4 weeks following transplantation into the spinal cord lesion and effectively digested chondroitin sulphate proteoglycans at the site of injury. There was evidence of sprouting within the corticospinal tract rostral to the lesion and an increase in the number of corticospinal axons caudal to the lesion, suggestive of axonal regeneration. Our results indicate that delivery of the chondroitinase enzyme can be achieved with the genetically modified OECs to increase axon growth following SCI. The combination of these two promising approaches is a potential strategy for promoting neural regeneration following SCI in veterinary practice and human patients

Pediatric-onset Evans syndrome: Heterogeneous presentation and high frequency of monogenic disorders including LRBA and CTLA4 mutations

Evans syndrome (ES) is defined by the combination of autoimmune hemolytic anemia and immune thrombocytopenia. Clinical presentation includes manifestations of immune dysregulation, found in primary immune deficiencies, autoimmune lymphoproliferative syndrome with FAS (ALPS-FAS), Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) and Lipopolysaccharide-Responsive vesicle trafficking Beige-like and Anchor protein (LRBA) defects. We report the clinical history and genetic results of 18 children with ES after excluding ALPS-FAS. Thirteen had organomegaly, five lymphocytic infiltration of non-lymphoid organs, nine hypogammaglobulinemia and fifteen anomalies in lymphocyte phenotyping. Seven patients had genetic defects: three CTLA4 mutations (c.151C>T; c.109+1092_568-512del; c.110-2A>G) identified by Sanger sequencing and four revealed by Next Generation Sequencing: LRBA (c.2450+1C>T), STAT3 gain-of-function (c.2147C>T; c.2144C>T) and KRAS (c.37G>T). No feature emerged to distinguish patients with or without genetic diagnosis. Our data on pediatric-onset ES should prompt physicians to perform extensive screening for mutations in the growing pool of genes involved in primary immune deficiencies with autoimmunity

Active perception during angiogenesis: filopodia speed up Notch selection of tip cells in silico and in vivo

How do cells make efficient collective decisions during tissue morphogenesis? Humans and other organisms use feedback between movement and sensing known as 'sensorimotor coordination' or 'active perception' to inform behaviour, but active perception has not before been investigated at a cellular level within organs. Here we provide the first proof of concept in silico/in vivo study demonstrating that filopodia (actin-rich, dynamic, finger-like cell membrane protrusions) play an unexpected role in speeding up collective endothelial decisions during the time-constrained process of 'tip cell' selection during blood vessel formation (angiogenesis). We first validate simulation predictions in vivo with live imaging of zebrafish intersegmental vessel growth. Further simulation studies then indicate the effect is due to the coupled positive feedback between movement and sensing on filopodia conferring a bistable switch-like property to Notch lateral inhibition, ensuring tip selection is a rapid and robust process. We then employ measures from computational neuroscience to assess whether filopodia function as a primitive (basal) form of active perception and find evidence in support. By viewing cell behaviour through the 'basal cognitive lens' we acquire a fresh perspective on the tip cell selection process, revealing a hidden, yet vital time-keeping role for filopodia. Finally, we discuss a myriad of new and exciting research directions stemming from our conceptual approach to interpreting cell behaviour. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'

Eye bank issues: II. Preservation techniques: warm versus cold storage

Most of the tissue used for penetrating keratoplasty is issued through eye banks that store the corneoscleral button either in hypothermic storage at 2–6°C or in organ culture at 31–37°C

Analysis of sexual phenotype and prezygotic fertility in natural populations of Fucus spiralis, F. vesiculosus (Fucaceae, Phaeophyceae) and their putative hybrids

In the genus Fucus, the character dioecy/hermaphroditism has undergone multiple state changes and hybridization is possible between taxa with contrasting mating systems, e.g. between the dioecious Fucus vesiculosus and the hermaphrodite F. spiralis. In the context of mating system evolution, we evaluated the potential consequences of hybridization by studying the variation in sexual phenotype and prezygotic fertility. Firstly, as a result of hybridization between the two sexual systems, gender variation may arise depending on the relative importance of genes with large versus small phenotypic effects. We thus qualitatively examined the extent of gender variation within and among individual hybrids in comparison with both parental species. Secondly, if hybridization breaks up co-adapted gene complexes, hybrid fertility may be reduced in comparison with both parental species. Therefore, we also quantified male and female prezygotic fertility in parental species and their hybrids in order to test for reduction in hybrid fitness. A total of 89 sexually mature individuals (20 F. spiralis, 40 F. vesiculosus, 10 hermaphrodite hybrids and 19 dioecious hybrids) were sampled in two geographically distant regions (France and Portugal) and six conceptacles per individual were observed. Within-individual variation was very restricted qualitatively – only one hybrid carried a conceptacle with a different sexual phenotype from the five others – as well as quantitatively. This suggests a simple genetic system for sex determination involving a few genes with major effects. In addition, analyses showed no significant decrease in hybrid fertility compared with parental species. Moreover, hybrids exhibited all sexual phenotypes, suggesting several generations of hybridization and backcrossing and, therefore, that hybrids are reproductively successful. Finally, the occurrence of sterile paraphyses in female and hermaphrodite individuals was interpreted as a relic of male function and suggests that, as in higher plants, evolution from hermaphroditism to dioecy may be the most parsimonious pathway

Enhanced Functional Recovery in MRL/MpJ Mice after Spinal Cord Dorsal Hemisection

Adult MRL/MpJ mice have been shown to possess unique regeneration capabilities. They are able to heal an ear-punched hole or an injured heart with normal tissue architecture and without scar formation. Here we present functional and histological evidence for enhanced recovery following spinal cord injury (SCI) in MRL/MpJ mice. A control group (C57BL/6 mice) and MRL/MpJ mice underwent a dorsal hemisection at T9 (thoracic vertebra 9). Our data show that MRL/MpJ mice recovered motor function significantly faster and more completely. We observed enhanced regeneration of the corticospinal tract (CST). Furthermore, we observed a reduced astrocytic response and fewer micro-cavities at the injury site, which appear to create a more growth-permissive environment for the injured axons. Our data suggest that the reduced astrocytic response is in part due to a lower lesion-induced increase of cell proliferation post-SCI, and a reduced astrocytic differentiation of the proliferating cells. Interestingly, we also found an increased number of proliferating microglia, which could be involved in the MRL/MpJ spinal cord repair mechanisms. Finally, to evaluate the molecular basis of faster spinal cord repair, we examined the difference in gene expression changes in MRL/MpJ and C57BL/6 mice after SCI. Our microarray data support our histological findings and reveal a transcriptional profile associated with a more efficient spinal cord repair in MRL/MpJ mice