Project description:Nociceptive neuropeptide CGRP acts directly on HSCs via the its receptor RAMP1/CALCRL, to promote egress by activating Gαs/Adenylyl cyclase/cAMP pathway.
Project description:The majority of allogeneic stem cell transplants are currently undertaken using G-CSF mobilized peripheral blood stem cells. G-CSF has diverse biological effects on a broad range of cells and IL-10 is a key regulator of many of these effects. Using mixed radiation chimeras in which the haematopoietic or non-haematopoietic compartments were wild-type (WT), IL-10–/–, G-CSFR–/– or combinations thereof we demonstrated that the attenuation of alloreactive T cell responses after with G-CSF mobilization required direct signalling of the T cell by both G-CSF and IL-10. IL-10 was generated principally by radio-resistant tissue, and was not required to be produced by T cells. G-CSF mobilization significantly modulated the transcription profile of CD4+CD25+ regulatory T cells, promoted their expansion in the donor and recipient and their depletion significantly increased graft-versus-host disease (GVHD). In contrast, stem cell mobilization with the CXCR4 antagonist AMD3100 did not alter the donor T cell’s ability to induce acute GVHD. These studies provide an explanation for the effects of G-CSF on T cell function and demonstrate that IL-10 is required to license regulatory function but T cell production of IL-10 is not itself required for the attenuation GVHD. Although administration of CXCR4 antagonists is an efficient means of stem cell mobilization, this fails to evoke the immunomodulatory effects seen during G-CSF mobilization. These data provide a compelling rationale for considering the immunological benefits of G-CSF in selecting mobilization protocols for allogeneic stem cell transplantation. Single colour, Illumina MouseRef-8 v2.0 Beadarrays.
Project description:Piloerection (goosebump) requires concerted actions of the hair follicle, the arrector pili muscle (APM), and the sympathetic nerve, providing a model to study interactions across epithelium, mesenchyme, and nerves. Here, we show that APMs and sympathetic nerves form a dual component niche to modulate hair follicle stem cell (HFSC) activity. Sympathetic nerves form synapse-like structures with HFSCs and regulate HFSCs through norepinephrine, whereas APMs maintain sympathetic innervation to HFSCs. Without norepinephrine signaling, HFSCs enter a deep quiescence state by down-regulating cell cycle machinery and mitochondria metabolism, while up-regulating quiescence regulators Lhx2, Foxp1, and Fgf18. During development, HFSC progeny secrets Sonic Hedgehog (SHH) to direct the formation of this APM-sympathetic nerve niche, which in turn controls hair follicle regeneration in adults. Our results reveal a reciprocal interdependence between a regenerative tissue and its niche at different stages, and illustrate that nerves can modulate stem cell quiescence through synapses and neurotransmitters.
Project description:The majority of allogeneic stem cell transplants are currently undertaken using G-CSF mobilized peripheral blood stem cells. G-CSF has diverse biological effects on a broad range of cells and IL-10 is a key regulator of many of these effects. Using mixed radiation chimeras in which the haematopoietic or non-haematopoietic compartments were wild-type (WT), IL-10–/–, G-CSFR–/– or combinations thereof we demonstrated that the attenuation of alloreactive T cell responses after with G-CSF mobilization required direct signalling of the T cell by both G-CSF and IL-10. IL-10 was generated principally by radio-resistant tissue, and was not required to be produced by T cells. G-CSF mobilization significantly modulated the transcription profile of CD4+CD25+ regulatory T cells, promoted their expansion in the donor and recipient and their depletion significantly increased graft-versus-host disease (GVHD). In contrast, stem cell mobilization with the CXCR4 antagonist AMD3100 did not alter the donor T cell’s ability to induce acute GVHD. These studies provide an explanation for the effects of G-CSF on T cell function and demonstrate that IL-10 is required to license regulatory function but T cell production of IL-10 is not itself required for the attenuation GVHD. Although administration of CXCR4 antagonists is an efficient means of stem cell mobilization, this fails to evoke the immunomodulatory effects seen during G-CSF mobilization. These data provide a compelling rationale for considering the immunological benefits of G-CSF in selecting mobilization protocols for allogeneic stem cell transplantation.
Project description:The intestine is a barrier tissue whose epithelium has high intrinsic turnover rate; intestinal stem cells, in response to signals from the niche, self-renew and produce progeny that differentiate to fulfill the continuous demand for new epithelial cells that are continuously shed into the lumen. The intestine is innervated by a dense network of peripheral nerves that controls nutrient absorption, intestinal motility, and visceral pain sensation. However, the roles of neurons in regulating epithelial cell homeostasis or regeneration remain as yet undiscovered. Here we investigate the effects of gut-innervating sympathetic neurons on epithelial cell repair following irradiation (IR)-induced gut injury. We observed that sympathetic innervation density in the gut increases post IR, while chemical sympathetic denervation impairs gut regeneration. Combining single cell RNA-sequencing and in vivo experiments, we discovered that sympathetic neurons regulate gut regeneration through modulation of IL22 production in type 3 innate lymphoid cells (ILC3) downstream of 2-adrenergic receptor signaling. These results define a novel neuroimmune axis important for intestinal regeneration.
Project description:The underlying mechanisms which are responsible and govern early haematopoietic differentiation during development are poorly understood. Gene expression comparison between pluripotent human embryonic stem cells and earliest haematopoietic progenitors may reveal novel transcripts and pathways and provide crucial insight into early haematopoietic lineage specification and development. Understanding of transcriptional cues that direct differentiation of human embryonic stem cells (hESC) to defined and functional cell types is essential for their future clinical applications. In this study we have undertaken a comparative transcriptional approach of haematopoietic progenitors derived from hESC at various stages of a feeder and serum free differentiation method and have shown that the largest transcriptional changes occur during the first four days of differentiation. Data mining based on molecular function pointed to RhoGTPase signalling as key regulator of this differentiation. Inhibition of this pathway using a chemical inhibitor (Y26732) resulted in a significant downregulation of haematopoietic progenitors throughout the differentiation window, thus uncovering a previously unappreciated role for RhoGTPase signalling in differentiation of hESC to haematopoietic lineages. There are a total of 4 samples within this microarray experiment with 2 biological replicates for each sample. Pluripotent human embryonic stem cells (day 0) underwent haematopoietic differentiation and at various stages of development (day 4, day 6, day8) differentiated cells were FACS sorted for two key haemangioblast markers, CD31 and KDR.
Project description:The underlying mechanisms which are responsible and govern early haematopoietic differentiation during development are poorly understood. Gene expression comparison between pluripotent human embryonic stem cells and earliest haematopoietic progenitors may reveal novel transcripts and pathways and provide crucial insight into early haematopoietic lineage specification and development. Understanding of transcriptional cues that direct differentiation of human embryonic stem cells (hESC) to defined and functional cell types is essential for their future clinical applications. In this study we have undertaken a comparative transcriptional approach of haematopoietic progenitors derived from hESC at various stages of a feeder and serum free differentiation method and have shown that the largest transcriptional changes occur during the first four days of differentiation. Data mining based on molecular function pointed to RhoGTPase signalling as key regulator of this differentiation. Inhibition of this pathway using a chemical inhibitor (Y26732) resulted in a significant downregulation of haematopoietic progenitors throughout the differentiation window, thus uncovering a previously unappreciated role for RhoGTPase signalling in differentiation of hESC to haematopoietic lineages.
Project description:Developmental pathways that orchestrate the fleeting transition of endothelial cells into haematopoietic stem cells remain undefined. Here we demonstrate a tractable approach for fully reprogramming adult mouse endothelial cells to haematopoietic stem cells (rEC-HSCs) through transient expression of the transcription-factor-encoding genes Fosb, Gfi1, Runx1, and Spi1 (collectively denoted hereafter as FGRS) and vascular-niche-derived angiocrine factors. The induction phase (days 0-8) of conversion is initiated by expression of FGRS in mature endothelial cells, which results in endogenous Runx1 expression. During the specification phase (days 8-20), RUNX1+ FGRS-transduced endothelial cells commit to a haematopoietic fate, yielding rEC-HSCs that no longer require FGRS expression. The vascular niche drives a robust self-renewal and expansion phase of rEC-HSCs (days 20-28). rEC-HSCs have a transcriptome and long-term self-renewal capacity similar to those of adult haematopoietic stem cells, and can be used for clonal engraftment and serial primary and secondary multi-lineage reconstitution, including antigen-dependent adaptive immune function. Inhibition of TGF? and CXCR7 or activation of BMP and CXCR4 signalling enhanced generation of rEC-HSCs. Pluripotency-independent conversion of endothelial cells into autologous authentic engraftable haematopoietic stem cells could aid treatment of haematological disorders.
Project description:Ebf genes regulate differentiation of several cell type. Ebf2 is expressed in Schwann cells and Ebf2-/- mice show among other phenotypical abnormalities a delay in the onset of myelination associated to a decreased expression of genes regulating myelination. In addition at one month of age Ebf2-/- mice show decreased motor conduction velocity and morphological alteration in sciatic nerves. Ebf2 target genes are unknown. To identify Ebf2 target genes with a role in myelination, we compared the expression profiles of sciatic nerves isolated from P2 Wt and Ebf2-/- mice by microarray analysis. We used microarray to find Ebf2 candidate target genes by comparing gene expression of Ebf2-/- sciatic nerve and wt nerves 2 days postnatally (P2) a time point in which Ebf2-/- pups present a delay in the onset of myelination.