TY - JOUR AB - The cerebral cortex contains multiple areas with distinctive cytoarchitectonical patterns, but the cellular mechanisms underlying the emergence of this diversity remain unclear. Here, we have investigated the neuronal output of individual progenitor cells in the developing mouse neocortex using a combination of methods that together circumvent the biases and limitations of individual approaches. Our experimental results indicate that progenitor cells generate pyramidal cell lineages with a wide range of sizes and laminar configurations. Mathematical modelling indicates that these outcomes are compatible with a stochastic model of cortical neurogenesis in which progenitor cells undergo a series of probabilistic decisions that lead to the specification of very heterogeneous progenies. Our findings support a mechanism for cortical neurogenesis whose flexibility would make it capable to generate the diverse cytoarchitectures that characterize distinct neocortical areas. AU - Llorca, Alfredo AU - Ciceri, Gabriele AU - Beattie, Robert J AU - Wong, Fong Kuan AU - Diana, Giovanni AU - Serafeimidou-Pouliou, Eleni AU - Fernández-Otero, Marian AU - Streicher, Carmen AU - Arnold, Sebastian J. AU - Meyer, Martin AU - Hippenmeyer, Simon AU - Maravall, Miguel AU - Marín, Oscar ID - 7202 JF - eLife TI - A stochastic framework of neurogenesis underlies the assembly of neocortical cytoarchitecture VL - 8 ER - TY - JOUR AB - Epidermal growth factor receptor (EGFR) signaling controls skin development and homeostasis inmice and humans, and its deficiency causes severe skin inflammation, which might affect epidermalstem cell behavior. Here, we describe the inflammation-independent effects of EGFR deficiency dur-ing skin morphogenesis and in adult hair follicle stem cells. Expression and alternative splicing analysisof RNA sequencing data from interfollicular epidermis and outer root sheath indicate that EGFR con-trols genes involved in epidermal differentiation and also in centrosome function, DNA damage, cellcycle, and apoptosis. Genetic experiments employingp53deletion in EGFR-deficient epidermis revealthat EGFR signaling exhibitsp53-dependent functions in proliferative epidermal compartments, aswell asp53-independent functions in differentiated hair shaft keratinocytes. Loss of EGFR leads toabsence of LEF1 protein specifically in the innermost epithelial hair layers, resulting in disorganizationof medulla cells. Thus, our results uncover important spatial and temporal features of cell-autonomousEGFR functions in the epidermis. AU - Amberg, Nicole AU - Sotiropoulou, Panagiota A. AU - Heller, Gerwin AU - Lichtenberger, Beate M. AU - Holcmann, Martin AU - Camurdanoglu, Bahar AU - Baykuscheva-Gentscheva, Temenuschka AU - Blanpain, Cedric AU - Sibilia, Maria ID - 6451 JF - iScience SN - 2589-0042 TI - EGFR controls hair shaft differentiation in a p53-independent manner VL - 15 ER - TY - JOUR AB - The cerebral cortex is composed of a large variety of distinct cell-types including projection neurons, interneurons and glial cells which emerge from distinct neural stem cell (NSC) lineages. The vast majority of cortical projection neurons and certain classes of glial cells are generated by radial glial progenitor cells (RGPs) in a highly orchestrated manner. Recent studies employing single cell analysis and clonal lineage tracing suggest that NSC and RGP lineage progression are regulated in a profound deterministic manner. In this review we focus on recent advances based mainly on correlative phenotypic data emerging from functional genetic studies in mice. We establish hypotheses to test in future research and outline a conceptual framework how epigenetic cues modulate the generation of cell-type diversity during cortical development. This article is protected by copyright. All rights reserved. AU - Amberg, Nicole AU - Laukoter, Susanne AU - Hippenmeyer, Simon ID - 27 IS - 1 JF - Journal of Neurochemistry TI - Epigenetic cues modulating the generation of cell type diversity in the cerebral cortex VL - 149 ER - TY - JOUR AB - Long non-coding (lnc) RNAs are numerous and found throughout the mammalian genome, and many are thought to be involved in the regulation of gene expression. However, the majority remain relatively uncharacterised and of uncertain function making the use of model systems to uncover their mode of action valuable. Imprinted lncRNAs target and recruit epigenetic silencing factors to a cluster of imprinted genes on the same chromosome, making them one of the best characterized lncRNAs for silencing distant genes in cis. In this study we examined silencing of the distant imprinted gene Slc22a3 by the lncRNA Airn in the Igf2r imprinted cluster in mouse. Previously we proposed that imprinted lncRNAs may silence distant imprinted genes by disrupting promoter-enhancer interactions by being transcribed through the enhancer, which we called the enhancer interference hypothesis. Here we tested this hypothesis by first using allele-specific chromosome conformation capture (3C) to detect interactions between the Slc22a3 promoter and the locus of the Airn lncRNA that silences it on the paternal chromosome. In agreement with the model, we found interactions enriched on the maternal allele across the entire Airn gene consistent with multiple enhancer-promoter interactions. Therefore, to test the enhancer interference hypothesis we devised an approach to delete the entire Airn gene. However, the deletion showed that there are no essential enhancers for Slc22a2, Pde10a and Slc22a3 within the Airn gene, strongly indicating that the Airn RNA rather than its transcription is responsible for silencing distant imprinted genes. Furthermore, we found that silent imprinted genes were covered with large blocks of H3K27me3 on the repressed paternal allele. Therefore we propose an alternative hypothesis whereby the chromosome interactions may initially guide the lncRNA to target imprinted promoters and recruit repressive chromatin, and that these interactions are lost once silencing is established. AU - Andergassen, Daniel AU - Muckenhuber, Markus AU - Bammer, Philipp C. AU - Kulinski, Tomasz M. AU - Theussl, Hans-Christian AU - Shimizu, Takahiko AU - Penninger, Josef M. AU - Pauler, Florian AU - Hudson, Quanah J. ID - 7399 IS - 7 JF - PLoS Genetics SN - 1553-7404 TI - The Airn lncRNA does not require any DNA elements within its locus to silence distant imprinted genes VL - 15 ER - TY - JOUR AU - Contreras, Ximena AU - Hippenmeyer, Simon ID - 6830 IS - 5 JF - Neuron SN - 08966273 TI - Memo1 tiles the radial glial cell grid VL - 103 ER - TY - GEN AB - The cerebral cortex contains multiple hierarchically organized areas with distinctive cytoarchitectonical patterns, but the cellular mechanisms underlying the emergence of this diversity remain unclear. Here, we have quantitatively investigated the neuronal output of individual progenitor cells in the ventricular zone of the developing mouse neocortex using a combination of methods that together circumvent the biases and limitations of individual approaches. We found that individual cortical progenitor cells show a high degree of stochasticity and generate pyramidal cell lineages that adopt a wide range of laminar configurations. Mathematical modelling these lineage data suggests that a small number of progenitor cell populations, each generating pyramidal cells following different stochastic developmental programs, suffice to generate the heterogenous complement of pyramidal cell lineages that collectively build the complex cytoarchitecture of the neocortex. AU - Llorca, Alfredo AU - Ciceri, Gabriele AU - Beattie, Robert J AU - Wong, Fong K. AU - Diana, Giovanni AU - Serafeimidou, Eleni AU - Fernández-Otero, Marian AU - Streicher, Carmen AU - Arnold, Sebastian J. AU - Meyer, Martin AU - Hippenmeyer, Simon AU - Maravall, Miguel AU - Marín, Oscar ID - 8547 T2 - bioRxiv TI - Heterogeneous progenitor cell behaviors underlie the assembly of neocortical cytoarchitecture ER - TY - JOUR AB - Background: Norepinephrine (NE) signaling has a key role in white adipose tissue (WAT) functions, including lipolysis, free fatty acid liberation and, under certain conditions, conversion of white into brite (brown-in-white) adipocytes. However, acute effects of NE stimulation have not been described at the transcriptional network level. Results: We used RNA-seq to uncover a broad transcriptional response. The inference of protein-protein and protein-DNA interaction networks allowed us to identify a set of immediate-early genes (IEGs) with high betweenness, validating our approach and suggesting a hierarchical control of transcriptional regulation. In addition, we identified a transcriptional regulatory network with IEGs as master regulators, including HSF1 and NFIL3 as novel NE-induced IEG candidates. Moreover, a functional enrichment analysis and gene clustering into functional modules suggest a crosstalk between metabolic, signaling, and immune responses. Conclusions: Altogether, our network biology approach explores for the first time the immediate-early systems level response of human adipocytes to acute sympathetic activation, thereby providing a first network basis of early cell fate programs and crosstalks between metabolic and transcriptional networks required for proper WAT function. AU - Higareda Almaraz, Juan AU - Karbiener, Michael AU - Giroud, Maude AU - Pauler, Florian AU - Gerhalter, Teresa AU - Herzig, Stephan AU - Scheideler, Marcel ID - 20 IS - 1 JF - BMC Genomics SN - 1471-2164 TI - Norepinephrine triggers an immediate-early regulatory network response in primary human white adipocytes VL - 19 ER - TY - GEN AB - Table S1. Genes with highest betweenness. Table S2. Local and Master regulators up-regulated. Table S3. Local and Master regulators down-regulated (XLSX 23 kb). AU - Higareda Almaraz, Juan AU - Karbiener, Michael AU - Giroud, Maude AU - Pauler, Florian AU - Gerhalter, Teresa AU - Herzig, Stephan AU - Scheideler, Marcel ID - 9807 TI - Additional file 1: Of Norepinephrine triggers an immediate-early regulatory network response in primary human white adipocytes ER - TY - GEN AB - Table S4. Counts per Gene per Million Reads Mapped. (XLSX 2751 kb). AU - Higareda Almaraz, Juan AU - Karbiener, Michael AU - Giroud, Maude AU - Pauler, Florian AU - Gerhalter, Teresa AU - Herzig, Stephan AU - Scheideler, Marcel ID - 9808 TI - Additional file 3: Of Norepinephrine triggers an immediate-early regulatory network response in primary human white adipocytes ER - TY - THES AB - Genomic imprinting is an epigenetic process that leads to parent of origin-specific gene expression in a subset of genes. Imprinted genes are essential for brain development, and deregulation of imprinting is associated with neurodevelopmental diseases and the pathogenesis of psychiatric disorders. However, the cell-type specificity of imprinting at single cell resolution, and how imprinting and thus gene dosage regulates neuronal circuit assembly is still largely unknown. Here, MADM (Mosaic Analysis with Double Markers) technology was employed to assess genomic imprinting at single cell level. By visualizing MADM-induced uniparental disomies (UPDs) in distinct colors at single cell level in genetic mosaic animals, this experimental paradigm provides a unique quantitative platform to systematically assay the UPD-mediated imbalances in imprinted gene expression at unprecedented resolution. An experimental pipeline based on FACS, RNA-seq and bioinformatics analysis was established and applied to systematically map cell-type-specific ‘imprintomes’ in the mouse brain. The results revealed that parental-specific expression of imprinted genes per se is rarely cell-type-specific even at the individual cell level. Conversely, when we extended the comparison to downstream responses resulting from imbalanced imprinted gene expression, we discovered an unexpectedly high degree of cell-type specificity. Furthermore, we determined a novel function of genomic imprinting in cortical astrocyte production and in olfactory bulb (OB) granule cell generation. These results suggest important functional implication of genomic imprinting for generating cell-type diversity in the brain. In addition, MADM provides a powerful tool to study candidate genes by concomitant genetic manipulation and fluorescent labelling of single cells. MADM-based candidate gene approach was utilized to identify potential imprinted genes involved in the generation of cortical astrocytes and OB granule cells. We investigated p57Kip2, a maternally expressed gene and known cell cycle regulator. Although we found that p57Kip2 does not play a role in these processes, we detected an unexpected function of the paternal allele previously thought to be silent. Finally, we took advantage of a key property of MADM which is to allow unambiguous investigation of environmental impact on single cells. The experimental pipeline based on FACS and RNA-seq analysis of MADM-labeled cells was established to probe the functional differences of single cell loss of gene function compared to global loss of function on a transcriptional level. With this method, both common and distinct responses were isolated due to cell-autonomous and non-autonomous effects acting on genotypically identical cells. As a result, transcriptional changes were identified which result solely from the surrounding environment. Using the MADM technology to study genomic imprinting at single cell resolution, we have identified cell-type-specific gene expression, novel gene function and the impact of environment on single cell transcriptomes. Together, these provide important insights to the understanding of mechanisms regulating cell-type specificity and thus diversity in the brain. AU - Laukoter, Susanne ID - 10 SN - 2663-337X TI - Role of genomic imprinting in cerebral cortex development ER -