Taz protects hematopoietic stem cells from an aging-dependent decrease in PU.1 activity

Specific functions of the immune system are essential to protect us from infections caused by pathogens such as viruses and bacteria. However, as we age, the immune system shows a functional decline that can be attributed in large part to age-associated defects in hematopoietic stem cells (HSCs)-the cells at the apex of the immune cell hierarchy. Here, we find that the Hippo pathway coactivator TAZ is potently induced in old HSCs and protects these cells from functional decline. We identify Clca3a1 as a TAZ-induced gene that allows us to trace TAZ activity in vivo. Using CLCA3A1 as a marker, we can isolate "young-like" HSCs from old mice. Mechanistically, Taz acts as coactivator of PU.1 and to some extent counteracts the gradual loss of PU.1 expression during HSC aging. Our work thus uncovers an essential role for Taz in a previously undescribed fail-safe mechanism in aging HSCs. Immune system function declines with age, a consequence of defects in hematopoietic stem cells (HSCs). Here the authors show that TAZ buffers age-related loss of PU.1 activity to maintain HSC functionality and identify the surface protein Clca3a1 as a marker of "young-like" HSCs, even in old mice

Hematopoietic stem cell gene editing and expansion: State-of-the-art technologies and recent applications.

Hematopoietic stem cell transplantation (HSCT) is a curative therapy for a range of hematological diseases, from leukemias to immunodeficiencies and anemias. The aim in using HSCT is to replace a patient's dysfunctional blood system with a functional one by transplanting healthy hematopoietic stem cells (HSCs). HSCs may be collected from a healthy donor (for allogeneic HSCT) or from the patient for genetic correction (for autologous HSCT gene therapies). Despite the curative potential of HSCT, several hurdles to its wider and safer use remain, including how to efficiently genetically correct HSCs and how to increase donor HSC numbers to improve the donor pool. In recent years, the development of state-of-the-art technologies, such as Cas9-AAV6 technologies and identification of the small molecule HSC agonist UM171, have accelerated progress in HSC gene editing and expansion. These translational research efforts were the focus of the Spring 2021 International Society for Experimental Hematology (ISEH) webinar. Here we present a summary and discussion of the implications of these new approaches to improve HSC-based therapy

EPI-Clone supplementary dataset: Single cell RNA-seq of clonally barcoded hematopoietic progenitors

This is the dataset supporting the EPI-Clone manuscript: scRNA-seq profiling of hematopoietic stem and progenitor cells (HSPCs) was performed with the 3' 10x Genomics profiling. Three experiments are included: Two where HSCs were clonally labeled with the LARRY system, transplanted to recipient mouse and profiled 4-5 months later (post-transplant hematopoiesis), and one where HSPCs were profiled straight from an unperturbed mouse.Dataset is a seurat (v4) object with the following assays, reductions and metadata:ASSAYS:AB: Antibody expression dataRNA: RNA expression profilesintegrated: Integration of DNA methylation data performed across experimental batches with two batch correction methods: CCA (https://satijalab.org/seurat/reference/runcca) and harmony (https://portals.broadinstitute.org/harmony/articles/quickstart.html).DIMENSIONALITY REDUCTIONpca_cca: PCA performed on the integrated data (CCA integration)umap_cca: UMAP computed on the integrated data (CCA integration)umap_harmony: UMAP computed on the integrated data (Harmony integration)METADATAExperiment: The experiment that the cell is from, values are "LARRY main experiment", "LARRY replicate" and "Native hematopoiesis"ProcessingBatch: Experiments were processed in several batches.CellType: Cell type annotationLARRY: Error corrected LARRY barcodepercent.mt: percentage of mitochondrial DNAnCount_RNA: Read count for the RNA modalitynFeature_RNA: Number of RNAs with at least one readnCount_AB: Read count for the surface protein modalitynFeature_AB: Number of ABs with at least one read</p

EPI-Clone dataset: Single cell targeted DNA methylation profiling of hematopoietic stem and progenitor cells

This is the dataset supporting the EPI-Clone manuscript: Targeted single cell methylation profiling of hematopoietic stem and progenitor cells (HSPCs) was performed with the scTAMseq method. Three experiments are included: Two where HSCs were clonally labeled with the LARRY system, transplanted to recipient mouse and profiled 4-5 months later (post-transplant hematopoiesis), and one where HSPCs were profiled straight from an unperturbed mouse.Dataset is a seurat (v4) object with the following assays, reductions and metadata:ASSAYS:AB: Antibody expression dataDNAm: DNA methylation data, containing binary observations (0: amplicon not observed, i.e. dropout or absence of DNA methylation, 1: amplicon observed, i.e. DNA methylation). See the paper on scTAMseqintegrated: Integration of DNA methylation data performed across experimental batches.DIMENSIONALITY REDUCTIONpca: PCA performed on the integrated dataumap: UMAP computed on the integrated dataFor strategies how to obtain dimensionality reduction that reflect clonal identity, please see the github page accompanying the manuscript.METADATAExperiment: The experiment that the cell is from, values are "LARRY main experiment", "LARRY replicate" and "Native hematopoiesis"ProcessingBatch: Experiments were processed in several batches.CellType: Cell type annotationLARRY: Error corrected LARRY barcodeLARRYSize: Size of the cloneGFP.or.Saphire: Identity of the donor mousePseudotime: Differentiation pseudotimePerformanceNonHhaI: Performance of the control amplicons in that cell</p

Micropattern-based platform as a physiologically relevant model to study epithelial morphogenesis and nephrotoxicity

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The Cdc42 GEF Intersectin 2 controls mitotic spindle orientation to form the lumen during epithelial morphogenesis.

Epithelial organs are made of tubes and cavities lined by a monolayer of polarized cells that enclose the central lumen. Lumen formation is a crucial step in the formation of epithelial organs. The Rho guanosine triphosphatase (GTPase) Cdc42, which is a master regulator of cell polarity, regulates the formation of the central lumen in epithelial morphogenesis. However, how Cdc42 is regulated during this process is still poorly understood. Guanine nucleotide exchange factors (GEFs) control the activation of small GTPases. Using the three-dimensional Madin-Darby canine kidney model, we have identified a Cdc42-specific GEF, Intersectin 2 (ITSN2), which localizes to the centrosomes and regulates Cdc42 activation during epithelial morphogenesis. Silencing of either Cdc42 or ITSN2 disrupts the correct orientation of the mitotic spindle and normal lumen formation, suggesting a direct relationship between these processes. Furthermore, we demonstrated this direct relationship using LGN, a component of the machinery for mitotic spindle positioning, whose disruption also results in lumen formation defects