Extracellular Vesicles in CNS Developmental Disorders.

The central nervous system (CNS) is the most complex structure in the body, consisting of multiple cell types with distinct morphology and function. Development of the neuronal circuit and its function rely on a continuous crosstalk between neurons and non-neural cells. It has been widely accepted that extracellular vesicles (EVs), mainly exosomes, are effective entities responsible for intercellular CNS communication. They contain membrane and cytoplasmic proteins, lipids, non-coding RNAs, microRNAs and mRNAs. Their cargo modulates gene and protein expression in recipient cells. Several lines of evidence indicate that EVs play a role in modifying signal transduction with subsequent physiological changes in neurogenesis, gliogenesis, synaptogenesis and network circuit formation and activity, as well as synaptic pruning and myelination. Several studies demonstrate that neural and non-neural EVs play an important role in physiological and pathological neurodevelopment. The present review discusses the role of EVs in various neurodevelopmental disorders and the prospects of using EVs as disease biomarkers and therapeutics.

A simple and efficient toolset for analysing mitochondrial trafficking in neuronal cells.

Mitochondria are crucial for cells, supplying up to 90% of the energy requirements for neurons. Their correct localisation is crucial and ensured by a transport system. Mitochondrial trafficking in neurons is particularly critical, because mitochondria must leave the soma and travel along the axon and dendritic network to facilitate neuronal function. Abnormal mitochondrial trafficking has been reported in several neurological disorders, therefore the ability to quantify and analyse mitochondrial trafficking is vital to improving our understanding of their pathogenesis. Commercial software currently lacks an automated approach for performing such quantitation. Here we demonstrate the development of the Mitochondrial Trafficking and Distribution (MiTrakD) analysis toolset, which consists of simple and free-to-use instructions for mitochondrial trafficking analysis using time-lapse microscopy. MiTrakD utilises existing Fiji (ImageJ) tools for semi-automated, fast and efficient analysis of mitochondrial trafficking and distribution, including velocity, abundance, localisation and distance travelled in neurons. We document MiTrakD's efficiency and accuracy by analysing mitochondrial trafficking using two-dimensional fluorescence images of cortical neurons of wild type mice after 6 days (DIV6), 10 days (DIV10) and 14 days (DIV14) of in vitro incubation. Using MiTrakD we have demonstrated that neurons at all developmental stages exhibited the same percentage of mobile mitochondria, all of which travel in equidistance. Interestingly, the mitochondria in neurons at DIV10 were in greater abundance and were faster than those at DIV6 and DIV14. We can also conclude that MiTrakD is more efficient than manual analysis and is an accurate and reliable tool for performing mitochondrial trafficking analysis in neuronal cells.

Meta-analysis Reveals Genome-Wide Significance at 15q13 for Nonsyndromic Clefting of Both the Lip and the Palate, and Functional Analyses Implicate GREM1 As a Plausible Causative Gene.

Nonsyndromic orofacial clefts are common birth defects with multifactorial etiology. The most common type is cleft lip, which occurs with or without cleft palate (nsCLP and nsCLO, respectively). Although genetic components play an important role in nsCLP, the genetic factors that predispose to palate involvement are largely unknown. In this study, we carried out a meta-analysis on genetic and clinical data from three large cohorts and identified strong association between a region on chromosome 15q13 and nsCLP (P = 8.13 × 10(-14) for rs1258763; relative risk (RR): 1.46, 95% confidence interval (CI): 1.32-1.61)) but not nsCLO (P = 0.27; RR: 1.09 (0.94-1.27)). The 5 kb region of strongest association maps downstream of Gremlin-1 (GREM1), which encodes a secreted antagonist of the BMP4 pathway. We show during mouse embryogenesis, Grem1 is expressed in the developing lip and soft palate but not in the hard palate. This is consistent with genotype-phenotype correlations between rs1258763 and a specific nsCLP subphenotype, since a more than two-fold increase in risk was observed in patients displaying clefts of both the lip and soft palate but who had an intact hard palate (RR: 3.76, CI: 1.47-9.61, Pdiff<0.05). While we did not find lip or palate defects in Grem1-deficient mice, wild type embryonic palatal shelves developed divergent shapes when cultured in the presence of ectopic Grem1 protein (P = 0.0014). The present study identified a non-coding region at 15q13 as the second, genome-wide significant locus specific for nsCLP, after 13q31. Moreover, our data suggest that the closely located GREM1 gene contributes to a rare clinical nsCLP entity. This entity specifically involves abnormalities of the lip and soft palate, which develop at different time-points and in separate anatomical regions.