Project description:Background: MicroRNAs (miRNAs) are short non-coding RNAs predicted to regulate one third of protein-coding genes via mRNA targeting. In conjunction with key transcription factors, such as the repressor REST (RE1 silencing transcription factor), miRNAs play crucial roles in neurogenesis, which requires a highly orchestrated program of gene expression to ensure the appropriate development and function of diverse neural cell types. Whilst previous studies have highlighted select groups of miRNAs during neural development, there remains a need for amenable models in which miRNA expression and function can be analyzed over the duration of neurogenesis. Principal Findings: We performed large-scale expression profiling of miRNAs in human NTera2/D1 (NT2) cells during retinoic acid (RA)-induced transition from progenitors to fully differentiated neural phenotypes. Our results revealed dynamic changes of miRNA patterns, resulting in distinct miRNA subsets that could be linked to specific neurodevelopmental stages. Moreover, the cell-type specific miRNA subsets were very similar in NT2-derived differentiated cells and human primary neurons and astrocytes. Further analysis identified miRNAs as putative regulators of REST, as well as candidate miRNAs targeted by REST. Finally, we confirmed the existence of two predicted miRNAs; pred-MIR191 and pred-MIR222 associated with SLAIN1 and FOXP2, respectively, and provided some evidence of their potential co-regulation. Conclusions: In the present study, we demonstrate that regulation of miRNAs occurs in precise patterns indicative of their roles in cell fate commitment, progenitor expansion and differentiation into neurons and glia. Furthermore, the similarity between our NT2 system and primary human cells suggests their roles in molecular pathways critical for human in vivo neurogenesis. The experiment consists of a total of 51 arrays: 29 retinoic acid time series arrays (0,2,4,6,8,12,14,21 and 28 days), 2 each of NT2-derived neurons and astrocytes, 12 primary human fetal astrocytes, 3 primary human embryonic astrocytes and 3 primary human neurons. Each condition has a minimum of 2 biological replicates. The samples were compared as single channel experiments. NOTE: The raw data files were submitted as generated in Quantarray with 2 channels, but due to issues with the control sample dye (Cy5 on Channel 1), only the Channel 2 (Cy3) data was analysed.

Project description:Background Information The costa is a prominent striated fiber that is found in protozoa of the Trichomonadidae family that present an undulating membrane. It is composed primarily of proteins that have not yet been explored. In this study, we used cell fractionation to obtain a highly enriched costa fraction whose structure and composition was further analyzed by electron microscopy and mass spectrometry. Results Electron microscopy of negatively stained samples revealed that the costa, which is a periodic structure with alternating electron-dense and electron-lucent bands, displays three distinct regions, named the head, neck and body. Fourier transform analysis showed that the electron-lucent bands present sub-bands with a regular pattern. An analysis of the costa fraction via one- and two-dimensional electrophoresis and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) allowed the identification of 54 hypothetical proteins. Fourteen of those proteins were considered to be major components of the fraction. Conclusions The costa of T. foetus is a complex and organized cytoskeleton structure made of a large number of proteins which is assembled into filamentous structures. Some of these proteins exhibit uncharacterized domains and no function related according to gene ontology, suggesting that the costa structure may be formed by a new class of proteins that differ from those previously described in other organisms. Seven of these proteins contain prefoldin domains displaying coiled-coil regions. This propriety is shared with proteins of the striated fibers of other protozoan as well as in intermediate filaments. Significance Our observations suggest the presence of a new class of the cytoskeleton filaments in T. foetus. We believe that our data could auxiliate in determine the specific locations of these proteins in the distinct regions that compose the costa, as well as to define the functional roles of each component. Therefore, our study will help in the better understanding of the organization and function of this structure in unicellular organisms.

Project description:Differentiated NT2 cells are a potentially useful model system to study herpes simples virus (HSV) replication in human neurons. These cells can be irreversibly differentiated into NT-neurons in the presence of retinoic acid and non-dividing cultures NT-neurons can be maintained for up to several months without retinoic acid. HSV is capable of infecting and replicating in differentiated NT-neurons and thus differentiated NT-neurons provide a ready source of human post-mitotic cells which can be useful to study certain aspects of the interaction of HSV and the neuron. Microarray analysis was used to examine how HSV-1 infection modulates cellular transcription in human NT-neurons, focusing on changes that take place during the first 24 hours following infection and compared to changes resulting from infection with inactivated virus. In addition, the transcriptional changes resulting from virus infection of neurons were compared to those observed in primary human fibroblasts. At early times after HSV infection a small number of cellular transcripts in NT-Neurons appear to be increased in abundance. Most of these transcripts that are up-regulated after infection are not unique to neuronal cells, and possibly represent a common cellular response to HSV infection. A few transcripts were not detected in infected human fibroblasts and may represent part of a transcriptional profile specific to this type of human neuronal cell. In contrast to the situation at early times after infection, analysis of cellular transcripts in NT-neurons at late times after infection is complicated by the overall profound decrease in cellular transcription. Thus, microarray analysis appeared to be most useful as a screening method for transcription changes following infection at early times after virus infection of NT-neurons. Two-condition experiment, HSV-1 infected versus uninfected NTNeurons, 4 independent biological replicate sets (uninfected/infected) in dual channel array setup (Cy3/Cy5).

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To compare the levels of expression of the different glycosyltransferases in order to explain the exclusive detection of LeX in the neurons

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