@article{14794, abstract = {Mosaic analysis with double markers (MADM) technology enables the sparse labeling of genetically defined neurons. We present a protocol for time-lapse imaging of cortical projection neuron migration in mice using MADM. We describe steps for the isolation, culturing, and 4D imaging of neuronal dynamics in MADM-labeled brain tissue. While this protocol is compatible with other single-cell labeling methods, the MADM approach provides a genetic platform for the functional assessment of cell-autonomous candidate gene function and the relative contribution of non-cell-autonomous effects. For complete details on the use and execution of this protocol, please refer to Hansen et al. (2022),1 Contreras et al. (2021),2 and Amberg and Hippenmeyer (2021).3}, author = {Hansen, Andi H and Hippenmeyer, Simon}, issn = {2666-1667}, journal = {STAR Protocols}, number = {1}, publisher = {Elsevier}, title = {{Time-lapse imaging of cortical projection neuron migration in mice using mosaic analysis with double markers}}, doi = {10.1016/j.xpro.2023.102795}, volume = {5}, year = {2024}, } @article{12875, abstract = {The superior colliculus (SC) in the mammalian midbrain is essential for multisensory integration and is composed of a rich diversity of excitatory and inhibitory neurons and glia. However, the developmental principles directing the generation of SC cell-type diversity are not understood. Here, we pursued systematic cell lineage tracing in silico and in vivo, preserving full spatial information, using genetic mosaic analysis with double markers (MADM)-based clonal analysis with single-cell sequencing (MADM-CloneSeq). The analysis of clonally related cell lineages revealed that radial glial progenitors (RGPs) in SC are exceptionally multipotent. Individual resident RGPs have the capacity to produce all excitatory and inhibitory SC neuron types, even at the stage of terminal division. While individual clonal units show no pre-defined cellular composition, the establishment of appropriate relative proportions of distinct neuronal types occurs in a PTEN-dependent manner. Collectively, our findings provide an inaugural framework at the single-RGP/-cell level of the mammalian SC ontogeny.}, author = {Cheung, Giselle T and Pauler, Florian and Koppensteiner, Peter and Krausgruber, Thomas and Streicher, Carmen and Schrammel, Martin and Özgen, Natalie Y and Ivec, Alexis and Bock, Christoph and Shigemoto, Ryuichi and Hippenmeyer, Simon}, issn = {0896-6273}, journal = {Neuron}, number = {2}, pages = {230--246.e11}, publisher = {Elsevier}, title = {{Multipotent progenitors instruct ontogeny of the superior colliculus}}, doi = {10.1016/j.neuron.2023.11.009}, volume = {112}, year = {2024}, } @article{12542, abstract = {In this issue of Neuron, Espinosa-Medina et al.1 present the TEMPO (Temporal Encoding and Manipulation in a Predefined Order) system, which enables the marking and genetic manipulation of sequentially generated cell lineages in vertebrate species in vivo.}, author = {Villalba Requena, Ana and Hippenmeyer, Simon}, issn = {1097-4199}, journal = {Neuron}, number = {3}, pages = {291--293}, publisher = {Elsevier}, title = {{Going back in time with TEMPO}}, doi = {10.1016/j.neuron.2023.01.006}, volume = {111}, year = {2023}, } @article{12679, abstract = {How to generate a brain of correct size and with appropriate cell-type diversity during development is a major question in Neuroscience. In the developing neocortex, radial glial progenitor (RGP) cells are the main neural stem cells that produce cortical excitatory projection neurons, glial cells, and establish the prospective postnatal stem cell niche in the lateral ventricles. RGPs follow a tightly orchestrated developmental program that when disrupted can result in severe cortical malformations such as microcephaly and megalencephaly. The precise cellular and molecular mechanisms instructing faithful RGP lineage progression are however not well understood. This review will summarize recent conceptual advances that contribute to our understanding of the general principles of RGP lineage progression.}, author = {Hippenmeyer, Simon}, issn = {0959-4388}, journal = {Current Opinion in Neurobiology}, keywords = {General Neuroscience}, number = {4}, publisher = {Elsevier}, title = {{Principles of neural stem cell lineage progression: Insights from developing cerebral cortex}}, doi = {10.1016/j.conb.2023.102695}, volume = {79}, year = {2023}, } @article{12562, abstract = {Presynaptic inputs determine the pattern of activation of postsynaptic neurons in a neural circuit. Molecular and genetic pathways that regulate the selective formation of subsets of presynaptic inputs are largely unknown, despite significant understanding of the general process of synaptogenesis. In this study, we have begun to identify such factors using the spinal monosynaptic stretch reflex circuit as a model system. In this neuronal circuit, Ia proprioceptive afferents establish monosynaptic connections with spinal motor neurons that project to the same muscle (termed homonymous connections) or muscles with related or synergistic function. However, monosynaptic connections are not formed with motor neurons innervating muscles with antagonistic functions. The ETS transcription factor ER81 (also known as ETV1) is expressed by all proprioceptive afferents, but only a small set of motor neuron pools in the lumbar spinal cord of the mouse. Here we use conditional mouse genetic techniques to eliminate Er81 expression selectively from motor neurons. We find that ablation of Er81 in motor neurons reduces synaptic inputs from proprioceptive afferents conveying information from homonymous and synergistic muscles, with no change observed in the connectivity pattern from antagonistic proprioceptive afferents. In summary, these findings suggest a role for ER81 in defined motor neuron pools to control the assembly of specific presynaptic inputs and thereby influence the profile of activation of these motor neurons.}, author = {Ladle, David R. and Hippenmeyer, Simon}, issn = {1522-1598}, journal = {Journal of Neurophysiology}, keywords = {Physiology, General Neuroscience}, number = {3}, pages = {501--512}, publisher = {American Physiological Society}, title = {{Loss of ETV1/ER81 in motor neurons leads to reduced monosynaptic inputs from proprioceptive sensory neurons}}, doi = {10.1152/jn.00172.2022}, volume = {129}, year = {2023}, } @unpublished{14647, abstract = {In the developing vertebrate central nervous system, neurons and glia typically arise sequentially from common progenitors. Here, we report that the transcription factor Forkhead Box G1 (Foxg1) regulates gliogenesis in the mouse neocortex via distinct cell-autonomous roles in progenitors and in postmitotic neurons that regulate different aspects of the gliogenic FGF signalling pathway. We demonstrate that loss of Foxg1 in cortical progenitors at neurogenic stages causes premature astrogliogenesis. We identify a novel FOXG1 target, the pro-gliogenic FGF pathway component Fgfr3, which is suppressed by FOXG1 cell-autonomously to maintain neurogenesis. Furthermore, FOXG1 can also suppress premature astrogliogenesis triggered by the augmentation of FGF signalling. We identify a second novel function of FOXG1 in regulating the expression of gliogenic ligand FGF18 in new born neocortical upper-layer neurons. Loss of FOXG1 in postmitotic neurons increases Fgf18 expression and enhances gliogenesis in the progenitors. These results fit well with the model that new born neurons secrete cues that trigger progenitors to produce the next wave of cell types, astrocytes. If FGF signalling is attenuated in Foxg1 null progenitors, they progress to oligodendrocyte production. Therefore, loss of FOXG1 transitions the progenitor to a gliogenic state, producing either astrocytes or oligodendrocytes depending on FGF signalling levels. Our results uncover how FOXG1 integrates extrinsic signalling via the FGF pathway to regulate the sequential generation of neurons, astrocytes, and oligodendrocytes in the cerebral cortex.}, author = {Bose, Mahima and Suresh, Varun and Mishra, Urvi and Talwar, Ishita and Yadav, Anuradha and Biswas, Shiona and Hippenmeyer, Simon and Tole, Shubha}, booktitle = {bioRxiv}, publisher = {Cold Spring Harbor Laboratory}, title = {{Dual role of FOXG1 in regulating gliogenesis in the developing neocortex via the FGF signalling pathway}}, doi = {10.1101/2023.11.30.569337}, year = {2023}, } @article{14683, abstract = {Mosaic analysis with double markers (MADM) technology enables the generation of genetic mosaic tissue in mice and high-resolution phenotyping at the individual cell level. Here, we present a protocol for isolating MADM-labeled cells with high yield for downstream molecular analyses using fluorescence-activated cell sorting (FACS). We describe steps for generating MADM-labeled mice, perfusion, single-cell suspension, and debris removal. We then detail procedures for cell sorting by FACS and downstream analysis. This protocol is suitable for embryonic to adult mice. For complete details on the use and execution of this protocol, please refer to Contreras et al. (2021).1}, author = {Amberg, Nicole and Cheung, Giselle T and Hippenmeyer, Simon}, issn = {2666-1667}, journal = {STAR Protocols}, keywords = {General Immunology and Microbiology, General Biochemistry, Genetics and Molecular Biology, General Neuroscience}, number = {1}, publisher = {Elsevier}, title = {{Protocol for sorting cells from mouse brains labeled with mosaic analysis with double markers by flow cytometry}}, doi = {10.1016/j.xpro.2023.102771}, volume = {5}, year = {2023}, } @inbook{14757, abstract = {The cerebral cortex is comprised of a vast cell-type diversity sequentially generated by cortical progenitor cells. Faithful progenitor lineage progression requires the tight orchestration of distinct molecular and cellular mechanisms regulating proper progenitor proliferation behavior and differentiation. Correct execution of developmental programs involves a complex interplay of cell intrinsic and tissue-wide mechanisms. Many studies over the past decades have been able to determine a plethora of genes critically involved in cortical development. However, only a few made use of genetic paradigms with sparse and global gene deletion to probe cell-autonomous vs. tissue-wide contribution. In this chapter, we will elaborate on the importance of dissecting the cell-autonomous and tissue-wide mechanisms to gain a precise understanding of gene function during radial glial progenitor lineage progression.}, author = {Villalba Requena, Ana and Amberg, Nicole and Hippenmeyer, Simon}, booktitle = {Neocortical Neurogenesis in Development and Evolution}, editor = {Huttner, Wieland}, pages = {169--191}, publisher = {Wiley}, title = {{Interplay of Cell‐autonomous Gene Function and Tissue‐wide Mechanisms Regulating Radial Glial Progenitor Lineage Progression}}, doi = {10.1002/9781119860914.ch10}, year = {2023}, } @article{12802, abstract = {Little is known about the critical metabolic changes that neural cells have to undergo during development and how temporary shifts in this program can influence brain circuitries and behavior. Inspired by the discovery that mutations in SLC7A5, a transporter of metabolically essential large neutral amino acids (LNAAs), lead to autism, we employed metabolomic profiling to study the metabolic states of the cerebral cortex across different developmental stages. We found that the forebrain undergoes significant metabolic remodeling throughout development, with certain groups of metabolites showing stage-specific changes, but what are the consequences of perturbing this metabolic program? By manipulating Slc7a5 expression in neural cells, we found that the metabolism of LNAAs and lipids are interconnected in the cortex. Deletion of Slc7a5 in neurons affects the postnatal metabolic state, leading to a shift in lipid metabolism. Additionally, it causes stage- and cell-type-specific alterations in neuronal activity patterns, resulting in a long-term circuit dysfunction.}, author = {Knaus, Lisa and Basilico, Bernadette and Malzl, Daniel and Gerykova Bujalkova, Maria and Smogavec, Mateja and Schwarz, Lena A. and Gorkiewicz, Sarah and Amberg, Nicole and Pauler, Florian and Knittl-Frank, Christian and Tassinari, Marianna and Maulide, Nuno and Rülicke, Thomas and Menche, Jörg and Hippenmeyer, Simon and Novarino, Gaia}, issn = {0092-8674}, journal = {Cell}, keywords = {General Biochemistry, Genetics and Molecular Biology}, number = {9}, pages = {1950--1967.e25}, publisher = {Elsevier}, title = {{Large neutral amino acid levels tune perinatal neuronal excitability and survival}}, doi = {10.1016/j.cell.2023.02.037}, volume = {186}, year = {2023}, } @article{11336, abstract = {The generation of a correctly-sized cerebral cortex with all-embracing neuronal and glial cell-type diversity critically depends on faithful radial glial progenitor (RGP) cell proliferation/differentiation programs. Temporal RGP lineage progression is regulated by Polycomb Repressive Complex 2 (PRC2) and loss of PRC2 activity results in severe neurogenesis defects and microcephaly. How PRC2-dependent gene expression instructs RGP lineage progression is unknown. Here we utilize Mosaic Analysis with Double Markers (MADM)-based single cell technology and demonstrate that PRC2 is not cell-autonomously required in neurogenic RGPs but rather acts at the global tissue-wide level. Conversely, cortical astrocyte production and maturation is cell-autonomously controlled by PRC2-dependent transcriptional regulation. We thus reveal highly distinct and sequential PRC2 functions in RGP lineage progression that are dependent on complex interplays between intrinsic and tissue-wide properties. In a broader context our results imply a critical role for the genetic and cellular niche environment in neural stem cell behavior.}, author = {Amberg, Nicole and Pauler, Florian and Streicher, Carmen and Hippenmeyer, Simon}, issn = {2375-2548}, journal = {Science Advances}, number = {44}, publisher = {American Association for the Advancement of Science}, title = {{Tissue-wide genetic and cellular landscape shapes the execution of sequential PRC2 functions in neural stem cell lineage progression}}, doi = {10.1126/sciadv.abq1263}, volume = {8}, year = {2022}, } @article{9794, abstract = {Lymph nodes (LNs) comprise two main structural elements: fibroblastic reticular cells that form dedicated niches for immune cell interaction and capsular fibroblasts that build a shell around the organ. Immunological challenge causes LNs to increase more than tenfold in size within a few days. Here, we characterized the biomechanics of LN swelling on the cellular and organ scale. We identified lymphocyte trapping by influx and proliferation as drivers of an outward pressure force, causing fibroblastic reticular cells of the T-zone (TRCs) and their associated conduits to stretch. After an initial phase of relaxation, TRCs sensed the resulting strain through cell matrix adhesions, which coordinated local growth and remodeling of the stromal network. While the expanded TRC network readopted its typical configuration, a massive fibrotic reaction of the organ capsule set in and countered further organ expansion. Thus, different fibroblast populations mechanically control LN swelling in a multitier fashion.}, author = {Assen, Frank P and Abe, Jun and Hons, Miroslav and Hauschild, Robert and Shamipour, Shayan and Kaufmann, Walter and Costanzo, Tommaso and Krens, Gabriel and Brown, Markus and Ludewig, Burkhard and Hippenmeyer, Simon and Heisenberg, Carl-Philipp J and Weninger, Wolfgang and Hannezo, Edouard B and Luther, Sanjiv A. and Stein, Jens V. and Sixt, Michael K}, issn = {1529-2916}, journal = {Nature Immunology}, pages = {1246--1255}, publisher = {Springer Nature}, title = {{Multitier mechanics control stromal adaptations in swelling lymph nodes}}, doi = {10.1038/s41590-022-01257-4}, volume = {23}, year = {2022}, } @article{11460, abstract = {Background: Proper cerebral cortical development depends on the tightly orchestrated migration of newly born neurons from the inner ventricular and subventricular zones to the outer cortical plate. Any disturbance in this process during prenatal stages may lead to neuronal migration disorders (NMDs), which can vary in extent from focal to global. Furthermore, NMDs show a substantial comorbidity with other neurodevelopmental disorders, notably autism spectrum disorders (ASDs). Our previous work demonstrated focal neuronal migration defects in mice carrying loss-of-function alleles of the recognized autism risk gene WDFY3. However, the cellular origins of these defects in Wdfy3 mutant mice remain elusive and uncovering it will provide critical insight into WDFY3-dependent disease pathology. Methods: Here, in an effort to untangle the origins of NMDs in Wdfy3lacZ mice, we employed mosaic analysis with double markers (MADM). MADM technology enabled us to genetically distinctly track and phenotypically analyze mutant and wild-type cells concomitantly in vivo using immunofluorescent techniques. Results: We revealed a cell autonomous requirement of WDFY3 for accurate laminar positioning of cortical projection neurons and elimination of mispositioned cells during early postnatal life. In addition, we identified significant deviations in dendritic arborization, as well as synaptic density and morphology between wild type, heterozygous, and homozygous Wdfy3 mutant neurons in Wdfy3-MADM reporter mice at postnatal stages. Limitations: While Wdfy3 mutant mice have provided valuable insight into prenatal aspects of ASD pathology that remain inaccessible to investigation in humans, like most animal models, they do not a perfectly replicate all aspects of human ASD biology. The lack of human data makes it indeterminate whether morphological deviations described here apply to ASD patients or some of the other neurodevelopmental conditions associated with WDFY3 mutation. Conclusions: Our genetic approach revealed several cell autonomous requirements of WDFY3 in neuronal development that could underlie the pathogenic mechanisms of WDFY3-related neurodevelopmental conditions. The results are also consistent with findings in other ASD animal models and patients and suggest an important role for WDFY3 in regulating neuronal function and interconnectivity in postnatal life.}, author = {Schaaf, Zachary A. and Tat, Lyvin and Cannizzaro, Noemi and Green, Ralph and Rülicke, Thomas and Hippenmeyer, Simon and Zarbalis, Konstantinos S.}, issn = {2040-2392}, journal = {Molecular Autism}, keywords = {Psychiatry and Mental health, Developmental Biology, Developmental Neuroscience, Molecular Biology}, publisher = {Springer Nature}, title = {{WDFY3 mutation alters laminar position and morphology of cortical neurons}}, doi = {10.1186/s13229-022-00508-3}, volume = {13}, year = {2022}, } @article{11449, abstract = {Mutations are acquired frequently, such that each cell's genome inscribes its history of cell divisions. Common genomic alterations involve loss of heterozygosity (LOH). LOH accumulates throughout the genome, offering large encoding capacity for inferring cell lineage. Using only single-cell RNA sequencing (scRNA-seq) of mouse brain cells, we found that LOH events spanning multiple genes are revealed as tracts of monoallelically expressed, constitutionally heterozygous single-nucleotide variants (SNVs). We simultaneously inferred cell lineage and marked developmental time points based on X chromosome inactivation and the total number of LOH events while identifying cell types from gene expression patterns. Our results are consistent with progenitor cells giving rise to multiple cortical cell types through stereotyped expansion and distinct waves of neurogenesis. This type of retrospective analysis could be incorporated into scRNA-seq pipelines and, compared with experimental approaches for determining lineage in model organisms, is applicable where genetic engineering is prohibited, such as humans.}, author = {Anderson, Donovan J. and Pauler, Florian and Mckenna, Aaron and Shendure, Jay and Hippenmeyer, Simon and Horwitz, Marshall S.}, issn = {2405-4720}, journal = {Cell Systems}, number = {6}, pages = {438--453.e5}, publisher = {Elsevier}, title = {{Simultaneous brain cell type and lineage determined by scRNA-seq reveals stereotyped cortical development}}, doi = {10.1016/j.cels.2022.03.006}, volume = {13}, year = {2022}, } @unpublished{10792, abstract = {Background Proper cerebral cortical development depends on the tightly orchestrated migration of newly born neurons from the inner ventricular and subventricular zones to the outer cortical plate. Any disturbance in this process during prenatal stages may lead to neuronal migration disorders (NMDs), which can vary in extent from focal to global. Furthermore, NMDs show a substantial comorbidity with other neurodevelopmental disorders, notably autism spectrum disorders (ASDs). Our previous work demonstrated focal neuronal migration defects in mice carrying loss-of-function alleles of the recognized autism risk gene WDFY3. However, the cellular origins of these defects in Wdfy3 mutant mice remain elusive and uncovering it will provide critical insight into WDFY3-dependent disease pathology . Methods Here, in an effort to untangle the origins of NMDs in Wdfy3lacZ mice, we employed mosaic analysis with double markers (MADM). MADM technology enabled us to genetically distinctly track and phenotypically analyze mutant and wild type cells concomitantly in vivo using immunofluorescent techniques. Results We revealed a cell autonomous requirement of WDFY3 for accurate laminar positioning of cortical projection neurons and elimination of mispositioned cells during early postnatal life. In addition, we identified significant deviations in dendritic arborization, as well as synaptic density and morphology between wild type, heterozygous, and homozygous Wdfy3 mutant neurons in Wdfy3-MADM reporter mice at postnatal stages. Limitations While Wdfy3 mutant mice have provided valuable insight into prenatal aspects of ASD pathology that remain inaccessible to investigation in humans, like most animal models, they do not a perfectly replicate all aspects of human ASD biology. The lack of human data makes it indeterminate whether morphological deviations described here apply to ASD patients. Conclusions Our genetic approach revealed several cell autonomous requirements of Wdfy3 in neuronal development that could underly the pathogenic mechanisms of WDFY3-related ASD conditions. The results are also consistent with findings in other ASD animal models and patients and suggest an important role for Wdfy3 in regulating neuronal function and interconnectivity in postnatal life.}, author = {Schaaf, Zachary and Tat, Lyvin and Cannizzaro, Noemi and Green, Ralph and Rülicke, Thomas and Hippenmeyer, Simon and Zarbalis, K}, issn = {2693-5015}, pages = {30}, publisher = {Research Square}, title = {{WDFY3 cell autonomously controls neuronal migration}}, doi = {10.21203/rs.3.rs-1316167/v1}, year = {2022}, } @article{10791, abstract = {The mammalian neocortex is composed of diverse neuronal and glial cell classes that broadly arrange in six distinct laminae. Cortical layers emerge during development and defects in the developmental programs that orchestrate cortical lamination are associated with neurodevelopmental diseases. The developmental principle of cortical layer formation depends on concerted radial projection neuron migration, from their birthplace to their final target position. Radial migration occurs in defined sequential steps, regulated by a large array of signaling pathways. However, based on genetic loss-of-function experiments, most studies have thus far focused on the role of cell-autonomous gene function. Yet, cortical neuron migration in situ is a complex process and migrating neurons traverse along diverse cellular compartments and environments. The role of tissue-wide properties and genetic state in radial neuron migration is however not clear. Here we utilized mosaic analysis with double markers (MADM) technology to either sparsely or globally delete gene function, followed by quantitative single-cell phenotyping. The MADM-based gene ablation paradigms in combination with computational modeling demonstrated that global tissue-wide effects predominate cell-autonomous gene function albeit in a gene-specific manner. Our results thus suggest that the genetic landscape in a tissue critically affects the overall migration phenotype of individual cortical projection neurons. In a broader context, our findings imply that global tissue-wide effects represent an essential component of the underlying etiology associated with focal malformations of cortical development in particular, and neurological diseases in general.}, author = {Hansen, Andi H and Pauler, Florian and Riedl, Michael and Streicher, Carmen and Heger, Anna-Magdalena and Laukoter, Susanne and Sommer, Christoph M and Nicolas, Armel and Hof, Björn and Tsai, Li Huei and Rülicke, Thomas and Hippenmeyer, Simon}, issn = {2753-149X}, journal = {Oxford Open Neuroscience}, number = {1}, publisher = {Oxford Academic}, title = {{Tissue-wide effects override cell-intrinsic gene function in radial neuron migration}}, doi = {10.1093/oons/kvac009}, volume = {1}, year = {2022}, } @unpublished{9082, abstract = {Acquired mutations are sufficiently frequent such that the genome of a single cell offers a record of its history of cell divisions. Among more common somatic genomic alterations are loss of heterozygosity (LOH). Large LOH events are potentially detectable in single cell RNA sequencing (scRNA-seq) datasets as tracts of monoallelic expression for constitutionally heterozygous single nucleotide variants (SNVs) located among contiguous genes. We identified runs of monoallelic expression, consistent with LOH, uniquely distributed throughout the genome in single cell brain cortex transcriptomes of F1 hybrids involving different inbred mouse strains. We then phylogenetically reconstructed single cell lineages and simultaneously identified cell types by corresponding gene expression patterns. Our results are consistent with progenitor cells giving rise to multiple cortical cell types through stereotyped expansion and distinct waves of neurogenesis. Compared to engineered recording systems, LOH events accumulate throughout the genome and across the lifetime of an organism, affording tremendous capacity for encoding lineage information and increasing resolution for later cell divisions. This approach can conceivably be computationally incorporated into scRNA-seq analysis and may be useful for organisms where genetic engineering is prohibitive, such as humans.}, author = {Anderson, Donovan J. and Pauler, Florian and McKenna, Aaron and Shendure, Jay and Hippenmeyer, Simon and Horwitz, Marshall S.}, booktitle = {bioRxiv}, publisher = {Cold Spring Harbor Laboratory}, title = {{Simultaneous identification of brain cell type and lineage via single cell RNA sequencing}}, doi = {10.1101/2020.12.31.425016}, year = {2021}, } @article{8546, abstract = {Brain neurons arise from relatively few progenitors generating an enormous diversity of neuronal types. Nonetheless, a cardinal feature of mammalian brain neurogenesis is thought to be that excitatory and inhibitory neurons derive from separate, spatially segregated progenitors. Whether bi-potential progenitors with an intrinsic capacity to generate both lineages exist and how such a fate decision may be regulated are unknown. Using cerebellar development as a model, we discover that individual progenitors can give rise to both inhibitory and excitatory lineages. Gradations of Notch activity determine the fates of the progenitors and their daughters. Daughters with the highest levels of Notch activity retain the progenitor fate, while intermediate levels of Notch activity generate inhibitory neurons, and daughters with very low levels of Notch signaling adopt the excitatory fate. Therefore, Notch-mediated binary cell fate choice is a mechanism for regulating the ratio of excitatory to inhibitory neurons from common progenitors.}, author = {Zhang, Tingting and Liu, Tengyuan and Mora, Natalia and Guegan, Justine and Bertrand, Mathilde and Contreras, Ximena and Hansen, Andi H and Streicher, Carmen and Anderle, Marica and Danda, Natasha and Tiberi, Luca and Hippenmeyer, Simon and Hassan, Bassem A.}, issn = { 22111247}, journal = {Cell Reports}, number = {10}, publisher = {Elsevier}, title = {{Generation of excitatory and inhibitory neurons from common progenitors via Notch signaling in the cerebellum}}, doi = {10.1016/j.celrep.2021.109208}, volume = {35}, year = {2021}, } @article{9188, abstract = {Genomic imprinting is an epigenetic mechanism that results in parental allele-specific expression of ~1% of all genes in mouse and human. Imprinted genes are key developmental regulators and play pivotal roles in many biological processes such as nutrient transfer from the mother to offspring and neuronal development. Imprinted genes are also involved in human disease, including neurodevelopmental disorders, and often occur in clusters that are regulated by a common imprint control region (ICR). In extra-embryonic tissues ICRs can act over large distances, with the largest surrounding Igf2r spanning over 10 million base-pairs. Besides classical imprinted expression that shows near exclusive maternal or paternal expression, widespread biased imprinted expression has been identified mainly in brain. In this review we discuss recent developments mapping cell type specific imprinted expression in extra-embryonic tissues and neocortex in the mouse. We highlight the advantages of using an inducible uniparental chromosome disomy (UPD) system to generate cells carrying either two maternal or two paternal copies of a specific chromosome to analyze the functional consequences of genomic imprinting. Mosaic Analysis with Double Markers (MADM) allows fluorescent labeling and concomitant induction of UPD sparsely in specific cell types, and thus to over-express or suppress all imprinted genes on that chromosome. To illustrate the utility of this technique, we explain how MADM-induced UPD revealed new insights about the function of the well-studied Cdkn1c imprinted gene, and how MADM-induced UPDs led to identification of highly cell type specific phenotypes related to perturbed imprinted expression in the mouse neocortex. Finally, we give an outlook on how MADM could be used to probe cell type specific imprinted expression in other tissues in mouse, particularly in extra-embryonic tissues.}, author = {Pauler, Florian and Hudson, Quanah and Laukoter, Susanne and Hippenmeyer, Simon}, issn = {0197-0186}, journal = {Neurochemistry International}, keywords = {Cell Biology, Cellular and Molecular Neuroscience}, number = {5}, publisher = {Elsevier}, title = {{Inducible uniparental chromosome disomy to probe genomic imprinting at single-cell level in brain and beyond}}, doi = {10.1016/j.neuint.2021.104986}, volume = {145}, year = {2021}, } @article{9601, abstract = {In mammalian genomes, differentially methylated regions (DMRs) and histone marks including trimethylation of histone 3 lysine 27 (H3K27me3) at imprinted genes are asymmetrically inherited to control parentally-biased gene expression. However, neither parent-of-origin-specific transcription nor imprints have been comprehensively mapped at the blastocyst stage of preimplantation development. Here, we address this by integrating transcriptomic and epigenomic approaches in mouse preimplantation embryos. We find that seventy-one genes exhibit previously unreported parent-of-origin-specific expression in blastocysts (nBiX: novel blastocyst-imprinted expressed). Uniparental expression of nBiX genes disappears soon after implantation. Micro-whole-genome bisulfite sequencing (µWGBS) of individual uniparental blastocysts detects 859 DMRs. We further find that 16% of nBiX genes are associated with a DMR, whereas most are associated with parentally-biased H3K27me3, suggesting a role for Polycomb-mediated imprinting in blastocysts. nBiX genes are clustered: five clusters contained at least one published imprinted gene, and five clusters exclusively contained nBiX genes. These data suggest that early development undergoes a complex program of stage-specific imprinting involving different tiers of regulation.}, author = {Santini, Laura and Halbritter, Florian and Titz-Teixeira, Fabian and Suzuki, Toru and Asami, Maki and Ma, Xiaoyan and Ramesmayer, Julia and Lackner, Andreas and Warr, Nick and Pauler, Florian and Hippenmeyer, Simon and Laue, Ernest and Farlik, Matthias and Bock, Christoph and Beyer, Andreas and Perry, Anthony C.F. and Leeb, Martin}, issn = {20411723}, journal = {Nature Communications}, number = {1}, publisher = {Springer Nature}, title = {{Genomic imprinting in mouse blastocysts is predominantly associated with H3K27me3}}, doi = {10.1038/s41467-021-23510-4}, volume = {12}, year = {2021}, } @article{9603, abstract = {Mosaic analysis with double markers (MADM) offers one approach to visualize and concomitantly manipulate genetically defined cells in mice with single-cell resolution. MADM applications include the analysis of lineage, single-cell morphology and physiology, genomic imprinting phenotypes, and dissection of cell-autonomous gene functions in vivo in health and disease. Yet, MADM can only be applied to <25% of all mouse genes on select chromosomes to date. To overcome this limitation, we generate transgenic mice with knocked-in MADM cassettes near the centromeres of all 19 autosomes and validate their use across organs. With this resource, >96% of the entire mouse genome can now be subjected to single-cell genetic mosaic analysis. Beyond a proof of principle, we apply our MADM library to systematically trace sister chromatid segregation in distinct mitotic cell lineages. We find striking chromosome-specific biases in segregation patterns, reflecting a putative mechanism for the asymmetric segregation of genetic determinants in somatic stem cell division.}, author = {Contreras, Ximena and Amberg, Nicole and Davaatseren, Amarbayasgalan and Hansen, Andi H and Sonntag, Johanna and Andersen, Lill and Bernthaler, Tina and Streicher, Carmen and Heger, Anna-Magdalena and Johnson, Randy L. and Schwarz, Lindsay A. and Luo, Liqun and Rülicke, Thomas and Hippenmeyer, Simon}, issn = {22111247}, journal = {Cell Reports}, number = {12}, publisher = {Cell Press}, title = {{A genome-wide library of MADM mice for single-cell genetic mosaic analysis}}, doi = {10.1016/j.celrep.2021.109274}, volume = {35}, year = {2021}, }