Hematopoietic stem cell (HSC) are regulated by their niche, which limits activation of HSCs, to ensure their maintenance and self-renewal.
Stroma-Derived Connective Tissue Growth Factor Maintains Cell Cycle Progression and Repopulation Activity of Hematopoietic Stem Cells In Vitro.
Cell line
View SamplesWe here show that the niche regulates the quality of the hematopoietic stem cells (HSCs) that are regenerated after transplantation. We find that a reduced level of Wnt5a in the niche regenerates dysfunctional HSCs, which do not successfully engraft secondary recipients. In particular, RNA sequencing shows a dysregulated Zeb1-associated gene expression of multiple genes involved in the small GTPase-dependent actin polymerization pathway. Misexpression of these genes results in reduced ability to direct polarized F-actin localization, leading to defects in adhesion, migratory behavior and homing to the bone marrow of secondary recipients. Our study further shows that the Wnt5a-haploinsufficient environment similarly affects BCR-ABLp185+ cells, which, in 42% of the studied recipients, fail to generate leukemia and, in the remaining cases, fail to transfer leukemia to secondary hosts. Thus, we show that Wnt5a in the niche is required to regenerate HSCs and leukemic cells with functional ability to rearrange the actin cytoskeleton which is required for successful engraftment. Overall design: Hematopoietic stem cells are regenerated in WT or Wnt5a-haploinsufficient niches. We profile LSK hematopoiteic stem cells after transplantation and three cell populations from the niche environment: endothelial cells (EC), osteoblastic cells (OBC), and mesenchymal cells (MSC)
Niche WNT5A regulates the actin cytoskeleton during regeneration of hematopoietic stem cells.
Cell line, Subject
View SamplesThe root cap-specific conversion of the auxin precursor indole-3-butyric acid (IBA) into the main auxin indole-3-acetic acid (IAA) generates a local auxin source which subsequently modulates both the periodicity and intensity of auxin response oscillations in the root tip of Arabidopsis, and consequently fine-tunes the spatiotemporal patterning of lateral roots. To explore downstream components of this signaling process, we investigated the early transcriptional regulations happening in the root tip during IBA-to-IAA conversion in Col-0 and ibr1 ibr3 ibr10 triple mutant after 6 hours of IBA treatment.
Root Cap-Derived Auxin Pre-patterns the Longitudinal Axis of the Arabidopsis Root.
Age, Specimen part, Treatment
View SamplesTissue-resident macrophages can derive from yolk sac macrophages, fetal liver monocytes or adult bone marrow monocytes. Whether these precursors can give rise to transcriptionally identical alveolar macrophages is unknown. Here, we transferred traceable yolk sac macrophages, fetal liver monocytes, adult bone marrow monocytes or adult alveolar macrophages as a control, into the empty alveolar macrophage niche of neonatal Csf2rb-/- mice. All precursors efficiently colonized the alveolar niche and generated alveolar macrophages that were transcriptionally almost identical, with only 22 genes that could be linked to their origin. Underlining the physiological relevance of our findings, all transfer-derived alveolar macrophages self-maintained within the lungs for up to 1 year and durably prevented alveolar proteinosis. Thus, precursor origin does not affect the development of functional self-maintaining tissue-resident macrophages.
Yolk Sac Macrophages, Fetal Liver, and Adult Monocytes Can Colonize an Empty Niche and Develop into Functional Tissue-Resident Macrophages.
Specimen part
View SamplesLateral root initiation was used as a model system to study the mechanisms behind auxin-induced cell division. Genome-wide transcriptional changes were monitored during the early steps of lateral root initiation. Inclusion of the dominant auxin signaling mutant solitary root1 (slr1) identified genes involved in lateral root initiation that act downstream of the AUX/IAA signaling pathway. Interestingly, key components of the cell cycle machinery were strongly defective in slr1, suggesting a direct link between AUX/IAA signaling and core cell cycle regulation. However, induction of the cell cycle in the mutant background by overexpression of the D-type cyclin (CYCD3;1) was able to trigger complete rounds of cell division in the pericycle that did not result in lateral root formation. Therefore, lateral root initiation can only take place when cell cycle activation is accompanied by cell fate respecification of pericycle cells. The microarray data also yielded evidence for the existence of both negative and positive feedback mechanisms that regulate auxin homeostasis and signal transduction in the pericycle, thereby fine-tuning the process of lateral root initiation.
Cell cycle progression in the pericycle is not sufficient for SOLITARY ROOT/IAA14-mediated lateral root initiation in Arabidopsis thaliana.
No sample metadata fields
View SamplesCoordination of cell division and pattern formation is central to tissue and organ development, and is particularly important in plants where walls prevent cell migration. Auxin and cytokinin are both critical for division and patterning, but it is unknown how these hormones converge to control tissue development. Here, we identify a genetic network that reinforces an early embryonic bias in auxin distribution to create a local, non-responding cytokinin source within the root vascular tissue. We provide experimental and theoretical evidence that these cells act as a local tissue organizer by positioning the domain of oriented cell divisions. We further demonstrate that the auxin-cytokinin interaction acts as a spatial incoherent feed forward loop, which is essential to generate distinct hormonal response zones, thus establishing a stable pattern within a growing vascular tissue.
Plant development. Integration of growth and patterning during vascular tissue formation in Arabidopsis.
Specimen part, Treatment
View SamplesEndocycle is an alternative cell cycle during which the DNA is replicated in the absence of cytokinesis, resulting in cellular endopolyploidy. The endocycle is frequenctly observed in plant species that grow under extreme conditions. Thus, endopolyploidy has been postulated to be a mechanism facilitating adaptive growth.
A Spatiotemporal DNA Endoploidy Map of the Arabidopsis Root Reveals Roles for the Endocycle in Root Development and Stress Adaptation.
Specimen part
View SamplesWe profiled transcripts from sorted phloem cells of wild-type and apl mutants to identify the genes regulated by APL in phloem.
Plant development. Arabidopsis NAC45/86 direct sieve element morphogenesis culminating in enucleation.
Specimen part
View SamplesSomatic polyploidy caused by endoreplication is observed in arthropods, molluscs, and vertebrates, but is especially prominent in higher plants where it has been postulated to be essential for cell growth and fate maintenance. However, a comprehensive understanding of the physiological significance of plant endopolyploidy has remained elusive. Here, we modeled and experimentally verified a high-resolution DNA endoploidy map of the developing Arabidopsis thaliana root, revealing a remarkable spatiotemporal control of DNA endoploidy levels across tissues and a strong dependence on stress signals. Cellular and transcriptomic analysis revealed that inhibition of endoreplication onset alters the nuclear-to-cellular volume ratio and change in expression of cell wall modifying genes, correlated with the appearance of cell structural changes. Our data indicate that endopolyploidy might serve to coordinate cell expansion with structural stability, and that spatiotemporal endoreplication pattern changes may buffer for stress conditions, which may explain the widespread occurrence of the endocycle in plant species growing in extreme or variable environments. Overall design: Two biological replicates of Col-0 were compared with three biological replicates of smr1
A Spatiotemporal DNA Endoploidy Map of the Arabidopsis Root Reveals Roles for the Endocycle in Root Development and Stress Adaptation.
Specimen part, Subject
View SamplesWhile the roles of parenchymal microglia in brain homeostasis and disease are fairly clear, other brain-resident myeloid cells remain less understood. By dissecting border regions and combining single-cell RNA sequencing with high-dimensional cytometry, bulk RNA-sequencing, fate-mapping and microscopy, we reveal the diversity of non-parenchymal brain macrophages. Border-associated macrophages (BAMs) residing in the dura mater, subdural meninges and choroid plexus consisted of distinct subsets with tissue-specific transcriptional signatures, and their cellular composition changed during postnatal development. BAMs exhibited a mixed ontogeny and subsets displayed distinct self-renewal capacities upon depletion and repopulation. Single-cell and fate-mapping analysis both suggested there is a unique microglial subset residing on the apical surface of the choroid plexus epithelium. Finally, gene network analysis and conditional deletion revealed IRF8 as a master regulator that drives the maturation and diversity of brain macrophages. Our results provide a framework for understanding host-macrophage interactions in the healthy and diseased brain. Overall design: sample of WT choroid plexus, sample of WT dura mater, sample of WT enriched SDM, sample of WT whole brain, sample of 9 months old APP/PS1 mice, sample of 16 months old APP/PS1 mice, sample of 16 months old WT mice, sample of Irf8 KO whole brain, sample of Irf8 KO choroid plexus, sample of Irf8 WT whole brain, sample of Irf8 WT choroid plexus, sample of dura mater with standard protocol and with ActD protocol, sample of choroid plexus with standard protocol and ActD protocol.
A single-cell atlas of mouse brain macrophages reveals unique transcriptional identities shaped by ontogeny and tissue environment.
Specimen part, Cell line, Subject
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