Project description:We found Acsl mutants have deficient neuroblast development. Further experiment confirmed that genes related to cell cycle and pluripotency were supressed in Acsl mutants.
Project description:Integration of spatial and temporal identity during Drosophila neurogenesis is due to spatial factors generating neuroblast-specific chromatin thereby biasing subsequent temporal transcription factor binding and producing neuroblast-specific neurons.
Project description:Stem cells establish cortical polarity and divide asymmetrically to simultaneously maintain themselves and generate differentiating offspring cells. Several chromatin modifiers have been identified as stemness factors in mammalian pluripotent stem cells, but whether these factors control stem cell polarity and asymmetric division has not been investigated so far. We addressed this question in Drosophila neural stem cells called neuroblasts. We identified the Tip60 chromatin remodeling complex and its interaction partner Myc to regulate target genes required for neuroblast maintenance. Knockdown of members of this complex results in loss of cortical polarity, symmetric neuroblast division and premature differentiation through nuclear entry of the transcription factor Prospero. We found that aPKC is the key target gene of Myc and the Tip60 complex subunit Domino regulating neuroblast polarity. Our transcriptome analysis further showed that Domino regulates the expression of mitotic spindle genes which were identified before as direct Myc targets. Our findings reveal an evolutionarily conserved functional link between Myc, the Tip60 complex and the molecular network controlling cell polarity and asymmetric cell division.
Project description:Notch signalling is involved in a multitude of developmental decisions and its aberrant activation is linked to many diseases, including cancers. One such example is the neural stem cell tumours that arise from constitutive Notch activity in Drosophila neuroblasts. To investigate how hyper-activation of Notch in larval neuroblasts leads to tumours, we combined results from profiling the upregulated mRNAs and mapping the regions bound by Su(H) (the core Notch pathway transcription factor ). This identified 127 putative direct Notch targets that were up-regulated in the hyperplastic tissue. These genes were highly enriched for transcription factors (TFs) and overlapped significantly with a previously identified regulatory programme dependent on the proneural transcription factor Asense. Included were genes associated with the neuroblast maintenance and self-renewal programme that we validated as Notch regulated in vivo. A second category contained so-called temporal transcription factors, which are involved in neuroblast progression. Normally expressed in specific time windows, several temporal transcription factors were ectopically expressed in the stem cell tumours, suggesting that Notch had reprogrammed the normal temporal hierarchy. Indeed, the Notch-induced hyperplasia was reduced by mutations affecting two of the temporal factors which, conversely, were sufficient to induce mild hyperplasia on their own. Altogether the results demonstrate that Notch induces neural stem cell tumors by promoting the expression of genes that contribute to stem cell identity and by reprogramming expression of temporal factors that regulate maturity.
Project description:Inactivation of prospero in Drosophila neuroblasts during larval stages induces unlimited neuroblast amplification leading to tumors that persist growing in adults. Tumors present in the ventral nerve cord of adult flies were dissected, dissociated and GFP-labelled tumor neuroblasts were isolated by FACS. 10000 neuroblasts were then processed for single-cell RNA-seq analysis. Single Cell RNA sequencing library were generated using the 10x Genomics Chromium Platform and sequenced on the Illumina Nextseq 500. eLife 2019;8:e50375 DOI: 10.7554/eLife.50375
Project description:The phenotypically characterized hTERT immortalized porcine olfactory bulb neuroblast cell line (OBGF400) was subjected to an extensive whole genome-scaled expression profile for establishing their use as an in vitro neuronal disease model system. Microarrays were used to provide a comprehensive knowledge underlying the genomic complexity and overall gene expression capacity of the immortalized OBGF400 cells. The analysis revealed the elaborate signaling mechanisms of this unique subpopulation of porcine neuronally committed progenitors that mirrors the intricate organization of postnatal neurongenic zones.
Project description:EMBRYONIC FLOWER1 (EMF1) is a plant specific gene crucial to Arabidopsis vegetative development. Loss of function mutants in the EMF1 gene mimic the phenotype caused by mutations in Polycomb Group protein (PcG) genes, which encode epigenetic repressors that regulate many aspects of eukaryotic development. In Arabidopsis, Polycomb Repressor Complex 2 (PRC2), made of PcG proteins, catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3) and PRC1-like proteins catalyze H2AK119 ubiquitination. Despite functional similarity to PcG proteins, EMF1 lacks sequence homology with known PcG proteins; thus its role in the PcG mechanism is unclear. To study the EMF1 functions and its mechanism of action, we performed genome-wide mapping of EMF1 binding and H3K27me3 modification sites in Arabidopsis seedlings. The EMF1 binding pattern is similar to that of H3K27me3 modification on the chromosomal and genic level. ChIPOTLe peak finding and clustering analyses both show that the highly trimethylated genes also have high enrichment level of EMF1 binding, termed EMF1_K27 genes. EMF1 interacts with regulatory genes, which are silenced to allow vegetative growth, and with genes specifying differentiated cell fates during vegetative development. H3K27me3 marks not only these genes but also some genes that are involved in endosperm development and maternal effects. Transcriptome analysis, coupled with the H3K27me3 pattern, of EMF1_K27 genes in emf1 and PRC2 mutants showed that EMF1 represses gene activities via diverse mechanisms and plays a novel role in the PcG mechanism. All experiments were done using two channels per chip, comparing DNA associated with immunoprecipitated EMF1 to control genomic DNA, DNA associated with immunoprecipitated histone H3 methylated at lysine 27 to control genomic DNA, or total RNA (converted to cDNA) to control genomic DNA. Two or three replicates per experiment are included.