Unknown,Transcriptomics,Genomics,Proteomics

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Cell-type based analysis of microRNA profiles in the mouse brain

ABSTRACT: MicroRNAs (miRNA) are implicated in brain development and function but the underlying mechanisms have been difficult to study in part due to cellular heterogeneity in neural circuits. To systematically analyze miRNA expression in neurons, we have established a miRNA tagging and affinity purification (miRAP) method that is targeted to cell types through the Cre-loxP binary system in mice. Our studies of the neocortex and cerebellum reveal the expression of a large fraction of known miRNAs with distinct profiles in glutamatergic and GABAergic neurons, and subtypes of GABAergic neurons. We further detected putative novel miRNAs, tissue or cell type-specific strand selection of miRNAs, and miRNA editing. Our method thus will facilitate a systematic analysis of miRNA expression and regulation in specific neuron types in the context of neuronal development, physiology, plasticity, pathology and disease models, and is generally applicable to other cell types and tissues. RNA was extracted from miRNA tagging samples(Ago2 IP or Myc IP), processed and sequenced on Illumina genome analyzer

ORGANISM(S): Mus musculus

SUBMITTER: Miao He

PROVIDER: E-GEOD-30286 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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:GABAergic interneurons are lost in conditions including epilepsy and CNS injury, but there are few culture models available to study their function. Towards the goal of obtaining renewable sources of GABAergic neurons, we used the molecular profile of a functionally-incomplete GABAergic precursor clone to screen 17 new clones isolated from GFP+ rat E14.5 cortex and ganglionic eminence (GE) that were generated by viral introduction of v-myc. The clones grow as neurospheres in medium with FGF2, and after withdrawal of FGF2 they exhibit varying patterns of differentiation. Transcriptional profiling and qPCR indicated that one clone (GE6) expresses high levels of mRNAs encoding Dlx1, 2, 5 and 6, glutamate decarboxylases, and presynaptic proteins including neuropeptide Y and somatostatin. Protein expression confirmed that GE6 is a progenitor with restricted differentiation giving rise mostly to neurons with GABAergic markers. In co-cultures with hippocampal neurons, GE6 neurons became electrically excitable and received both inhibitory and excitatory synapses. After withdrawal of FGF2 in cultures of GE6 alone, neurons matured to express BetaIII-tubulin, and staining for synaptophysin and vesicular GABA transporter (VGAT) were robust after 1-2 weeks of differentiation. GE6 neurons also became electrically excitable and displayed synaptic activity, but synaptic currents were carried by chloride and were blocked by bicuculline. The results suggest that the GE6 clone, which is ventrally derived from the GE, resembles GABAergic interneuron progenitors that migrate into the developing forebrain. This is the first report of a relatively stable fetal clone that can be differentiated into GABAergic interneurons with functional synapses. The purpose was to compare differentiation patterns of several different immortalized rat neural progenitor clones to identify early stages in differentiation. The cell clones studies were: GE6 (GABAergic neuronal precursor), GE2 (non-neuronal precursor, CTX8 (multipotential precursor), L2.2 (interneuronal precursor), and L2.3 (multipotential precursor). Five rat neural precursor cell clones were compared at three different time points following FGF2 withdrawal, which triggers differentiation. Three sister culture replicates were performed for each cell clone and time point, yielding 45 samples. One microarray failed so we have 44 microarray results in the dataset.

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Cell-type based analysis of microRNA profiles in the mouse brain

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