The role of Gpi-anchored axonal glycoproteins in neural development and neurological disorders.

This review article focuses on the Contactin (CNTN) subset of the Immunoglobulin supergene family (IgC2/FNIII molecules), whose components share structural properties (the association of Immunoglobulin type C2 with Fibronectin type III domains), as well as a general role in cell contact formation and axonal growth control. IgC2/FNIII molecules include 6 highly related components (CNTN 1-6), associated with the cell membrane via a Glycosyl Phosphatidyl Inositol (GPI)-containing lipid tail. Contactin 1 and Contactin 2 share ~50 (49.38)% identity at the aminoacid level. They are components of the cell surface, from which they may be released in soluble forms. They bind heterophilically to multiple partners in cis and in trans, including members of the related L1CAM family and of the Neurexin family Contactin-associated proteins (CNTNAPs or Casprs). Such interactions are important for organising the neuronal membrane, as well as for modulating the growth and pathfinding of axon tracts. In addition, they also mediate the functional maturation of axons by promoting their interactions with myelinating cells at the nodal, paranodal and juxtaparanodal regions. Such interactions also mediate differential ionic channels (both Na(+) and K(+)) distribution, which is of critical relevance in the generation of the peak-shaped action potential. Indeed, thanks to their interactions with Ankyrin G, Na(+) channels map within the nodal regions, where they drive axonal depolarization. However, no ionic channels are found in the flanking Contactin1-containing paranodal regions, where CNTN1 interactions with Caspr1 and with the Ig superfamily component Neurofascin 155 in cis and in trans, respectively, build a molecular barrier between the node and the juxtaparanode. In this region K(+) channels are clustered, depending upon molecular interactions with Contactin 2 and with Caspr2. In addition to these functions, the Contactins appear to have also a role in degenerative and inflammatory disorders: indeed Contactin 2 is involved in neurodegenerative disorders with a special reference to the Alzheimer disease, given its ability to work as a ligand of the Alzheimer Precursor Protein (APP), which results in increased Alzheimer Intracellular Domain (AICD) release in a γ-secretase-dependent manner. On the other hand Contactin-1 drives Notch signalling activation via the Hes pathway, which could be consistent with its ability to modulate neuroinflammation events, and with the possibility that Contactin 1-dependent interactions may participate to the pathogenesis of the Multiple Sclerosis and of other inflammatory disorders

Methodological standards, quality of reporting, and regulatory compliance in animal research on amyotrophic lateral sclerosis: a systematic review

Objectives The amyotrophic lateral sclerosis (ALS) research community was one of the first to adopt methodology guidelines to improve preclinical research reproducibility. We here present the results of a systematic review to investigate how the standards in this field changed over the 10-year period during which the guidelines were first published (2007) and updated (2010). Methods We searched for papers reporting ALS research on SOD1 (superoxide dismutase 1) mice published between 2005 and 2015 on the ISI Web of Science database, resulting in a sample of 569 papers to review, after triage. Two scores—one for methodological quality, one for regulatory compliance—were built from weighted sums of separate sets of items, and subjected to multivariable regression analysis, to assess how these related to publication year, type of study, country of origin and journal. Results Reporting standards improved over time. Of papers published after the first ALS guidelines were made public, fewer than 9% referred specifically to these. Of key research parameters, only three (genetic background, number of transgenes and group size) were reported in >50% of the papers. Information on housing conditions, randomisation and blinding was absent in over two-thirds of the papers. Group size was among the best reported parameters, but the majority reported using fewer than the recommended sample size and only two studies clearly justified group size. Conclusions General methodological standards improved gradually over a period of 8–10 years, but remained generally comparable with related fields with no specific guidelines, except with regard to severity. Only 11% of ALS studies were classified in the highest severity level (animals allowed to reach death or moribund stages), substantially below the proportion in studies of comparable neurodegenerative diseases such as Huntington’s. The existence of field-specific guidelines, although a welcome indication of concern, seems insufficient to ensure adherence to high methodological standards. Other mechanisms may be required to improve methodological and welfare standards

Excitatory granule neuron precursors orchestrate laminar localization and differentiation of cerebellar inhibitory interneuron subtypes

GABAergic interneurons migrate long distances through stereotyped migration programs toward specific laminar positions. During their migration, GABAergic interneurons are morphologically alike but then differentiate into a rich array of interneuron subtypes critical for brain function. How interneuron subtypes acquire their final phenotypic traits remains largely unknown. Here, we show that cerebellar molecular layer GABAergic interneurons, derived from the same progenitor pool, use separate migration paths to reach their laminar position and differentiate into distinct basket cell (BC) and stellate cell (SC) GABAergic interneuron subtypes. Using two-photon live imaging, we find that SC final laminar position requires an extra step of tangential migration supported by a subpopulation of glutamatergic granule cells (GCs). Conditional depletion of GCs affects SC differentiation but does not affect BCs. Our results reveal how timely feedforward control of inhibitory interneuron migration path regulates their terminal differentiation and, thus, establishment of the local inhibitory circuit assembly

Development of targeted STORM for super resolution imaging of biological samples using digital micro-mirror device

We demonstrate a simple illumination system based on a digital mirror device which allows for fine control over the power and pattern of illumination. We apply this to localization microscopy (LM), specifically stochastic optical reconstruction microscopy (STORM). Using this targeted STORM, we were able to image a selected area of a labelled cell without causing photo-damage to the surrounding areas of the cell

The Role Of Semaphorin3f (sema3f) In Neutrophilic Inflammation

Conference Abstract

All-trans retinoic acid-induced downregulation of annexin II expression in myeloid leukaemia cell lines is not confined to acute promyelocytic leukaemia

Most acute promyelocytic leukaemia (APL) patients suffer from disordered haemostasis. APL can be treated successfully in most instances by all-trans retinoic acid (ATRA) therapy, which induces endpoint maturation of the leukaemic promyelocytes with the characteristic t(15;17). Annexin II (AnII), a profibrinolytic protein, has been implicated in the bleeding manifestation seen in APL. Our group has shown previously that high levels of AnII are expressed on other acute myeloid leukaemia subtypes that are sometimes associated with disordered haemostasis, albeit less frequently than APL. This study examined the effects of ATRA on AnII expression and cell differentiation, on myeloid leukaemia cell lines to determine whether a regulatory influence on AnII may contribute to the return of haemostatic stability in APL following treatment. The results confirmed that AnII expression in the APL cell line (NB4) was significantly downregulated in response to ATRA (P < 0·01), with associated morphological and immunophenotypical evidence of myeloid differentiation. ATRA also downregulated AnII expression on other myeloid cell lines, albeit to a lesser extent than observed on NB4 cells. The results provide evidence that ATRA may resolve the hyperfibrinolysis in APL by downregulation of AnII expression