Project description:Our goal was to transcriptionally profile Prdm1+ cell lineages of maternal and embryonic origin in mid-gestation mouse placenta in order to study vascular mimicry and additional processes in the placenta.
Project description:Our goal was to transcriptionally profile Prdm1+ cell lineages of maternal and embryonic origin in mid-gestation mouse placenta in order to study vascular mimicry and additional processes in the placenta. Profiling of 61 single cells and 17 clusters of 2 or 3 cells chosen based on expression of Prdm1, a paternally inherited Prdm1-Venus fluorescent reporter, progenitor trophoblast marker Gjb3 and spiral artery trophoblast giant cell marker Prl7b1.
Project description:Langerhans cell histiocytosis (LCH) is a potentially fatal myeloid neoplasia, stemming from the mononuclear phagocyte (MNP) system. Discrimination of neoplastic cells that share features with normal MNPs is essential for mapping disease origin and pathogenesis. Here, we performed a deep profiling of LCH cells combining single cell RNA-seq and protein analysis enabling us to assess their heterogeneity and compare to their normal counterparts within the tumor microenvironment. Downstream analysis revealed LCH signatures pointing to senescence and tumor immune surveillance escape mechanisms. Developmentally, two major LCH arms, phenotypically resembling DC2 and monocyte/DC3 lineages, were identified and validated in situ across different pathological tissue sites using high-throughput microscopy. The present results support a dual origin model of LCH with an underlying neoplastic hit prior to the fate commitment to DC2 and monocyte/DC3 lineages, and provides basis for development of future targets in LCH and other histiocytic disorders.
Project description:Chemical cross-linking coupled to mass spectrometry was used to study the architecture and conformational state(s) of the Drosophila melanogaster origin replication complex (ORC). Two versions of the ORC were subjected to cross-linking with the amine-reactive reagents, disuccinimidyl suberate (DSS). One was a complex with truncated subunits (“core complex”), one with full-length sequences of all six subunits (“full-length complex”).
Project description:Hematopoiesis occurs in distinct waves. ‘Definitive’ hematopoietic stem cells (HSC) with the potential for all blood lineages emerge in the aorta-gonado-mesonephros (AGM), while ‘primitive’ progenitors, whose potential is thought to be limited to erythrocytes, megakaryocytes and macrophages (MΦ), arise earlier in the yolk sac (YS). Here, we questioned whether other YS lineages exist that have not been identified, partially owing to limitations of current lineage tracing models. We established the use of Cdh5CreERT2 for hematopoietic fate mapping, which revealed the YS origin of mast cells (MC). YS derived MC are replaced by definitive MC, which maintain themselves independently from the BM in the adult. Replacement occurs with tissue specific kinetics. MC in the skin, but not other organs, remain largely YS derived prenatally and are phenotypically and transcriptomically distinct from definite adult MC. We conclude that dual hematopoietic origin is not MΦ specific, but shared between these two myeloid lineages.
Project description:Induced pluripotent stem cells (iPSCs) have been derived from various somatic cell populations through ectopic expression of defined factors. It remains unclear whether iPSCs generated from different cell types are molecularly and functionally similar. Here, we show that iPSCs obtained from fibroblasts, hematopoietic and myogenic cells exhibit distinct transcriptional and epigenetic patterns. Moreover, we demonstrate that cellular origin influences the in vitro differentiation potentials of iPSCs into embryoid bodies (EBs) and different hematopoietic cells. Importantly, continuous passaging of iPSCs largely attenuates these differences. Our results suggest that low-passage iPSCs retain a transient epigenetic memory of their somatic cells of origin, which manifests as differential gene expression and ltered differentiation capacity. These observations might affect ongoing attempts to use iPSCs for disease modeling and also could be exploited for potential therapeutic applications to enhance differentiation into desired cell lineages. Keywords: DNA methylation profiling Direct comparison of DNA methylation in iPS cells derived from different tissues
Project description:Background: The terminal duct lobular unit (TDLU) is the most dynamic structure in the human breast and the putative site of origin of human breast cancer. Although stromal cells contribute to a specialized microenvironment in many organs, this component remains largely understudied in the human breast. We here demonstrate the impact on epithelium of two lineages of breast stromal fibroblasts, one of which accumulates in the TDLU while the other resides outside the TDLU in the interlobular stroma. Methods: The two lineages are prospectively isolated by FACS based on different expression levels of CD105 and CD26. The characteristics of the two fibroblast lineages are assessed by immunocytochemical staining and gene expression analysis. The differentiation capacity of the two fibroblast populations is determined by exposure to specific differentiating conditions followed by analysis of adipogenic and osteogenic differentiation. To test whether the two fibroblast lineages are functionally imprinted by their site of origin, single cell sorted CD271low/MUC1high normal breast luminal epithelial cells are plated on fibroblast feeders for the observation of morphological development. Epithelial structure formation and polarization is shown by immunofluorescence and digitalized quantification of immunoperoxidase stained cultures. Results: Lobular fibroblasts are CD105high/CD26low while interlobular fibroblasts are CD105low/CD26high. Once isolated the two lineages remain phenotypically stable and functionally distinct in culture. Lobular fibroblasts have properties in common with bone marrow derived mesenchymal stem cells and they specifically convey growth and branching morphogenesis of epithelial progenitors. Conclusions: Two distinct functionally specialized fibroblast lineages exist in the normal human breast, of which the lobular fibroblasts have properties in common with mesenchymal stem cells and support epithelial growth and morphogenesis. We propose that lobular fibroblasts constitute a specialized microenvironment for human breast luminal epithelial progenitors, i.e. the putative precursors of breast cancer.