Project description:Stem cell dynamics in the lung govern homeostasis, repair, and regeneration, yet there is still much unknown about the mechanisms of these processes. Furthermore, incongruencies between murine and human physiology limit the translation of some findings. In this work, we address these limitations by using a transgenic pig model to identify two populations of LGR5+ cells in the lung that are present in the human but that are absent from the mouse. Using RNA sequencing, 3D imaging, organoid models, and differentiation assays, we determine that in the fetal lung, epithelial LGR5 expression is transient in a subpopulation of developing lung bud tips. While epithelial LGR5 expression is absent from postnatal lung, it is reactivated in some organoids derived from basal airway cells. A separate population of LGR5+ cells is mesenchymal, surrounds developing and mature airways, is closely associated with nerve fibers, and acts as a multipotent progenitor cell capable of supporting the airway basal cell niche. These results point to two roles for LGR5 in orchestrating stem and progenitor cell dynamics, and provide a physiologically relevant model for further studies on the role of these populations in repair and regeneration.
Project description:Stem cell dynamics in the lung govern homeostasis, repair, and regeneration, yet there is still much unknown about the mechanisms of these processes. Furthermore, incongruencies between murine and human physiology limit the translation of some findings. In this work, we address these limitations by using a transgenic pig model to identify two populations of LGR5+ cells in the lung that are present in the human but that are absent from the mouse. Using RNA sequencing, 3D imaging, organoid models, and differentiation assays, we determine that in the fetal lung, epithelial LGR5 expression is transient in a subpopulation of developing lung bud tips. While epithelial LGR5 expression is absent from postnatal lung, it is reactivated in some organoids derived from basal airway cells. A separate population of LGR5+ cells is mesenchymal, surrounds developing and mature airways, is closely associated with nerve fibers, and acts as a multipotent progenitor cell capable of supporting the airway basal cell niche. These results point to two roles for LGR5 in orchestrating stem and progenitor cell dynamics, and provide a physiologically relevant model for further studies on the role of these populations in repair and regeneration.
Project description:Using a transgenic pig expressing H2B-GFP under the control of the endogenous LGR5 promoter, we used fluorescence activated cell sorting to isolate LGR5-high and LGR5-negative epidermal cells to generate mRNA profiles of the hair follicle stem cell population, n=2 pigs. Bulk RNAseq samples were prepared from porcine cells, at least 500ng of RNA was extracted from sorted LGR5-GFP-high or LGR5-GFP-negative populations. RNAseq was performed externally by GENEWIZ; library preparation with poly(A) selection was performed followed by paired end 150bp sequencing on Illumina HiSeq.
Project description:As transgenic INSC94Y-pigs develop a stable diabetic phenotype we were able to study the influence of elevated blood glucose levels on primary immune cells in vivo. We investigated the neutrophil proteome and compared data of transgenic animals to a control group. A total of 2371 proteins describing the whole neutrophil proteome were identified, including 396 proteins (17% of proteome) newly associated to expression in porcine neutrophils. Our studies provide novel information on the porcine granulocyte proteome and contribute to a better understanding of molecular mechanisms involved in altered immune cell function in diabetes. The data presented here is highly relevant for veterinary medicine and has translational quality for diabetes in human.
Project description:Lgr5+ crypt base columnar cells, the operational intestinal stem cells (ISCs), are thought to be dispensable for small intestinal (SI) homeostasis. Using a novel Lgr5-2A-DTR (Diphtheria Toxin Receptor) model which ablates Lgr5+ cells with near-complete efficiency and retains endogenous levels of Lgr5 expression, we show that persistent depletion of Lgr5+ ISCs in fact compromises SI epithelial integrity and reduces epithelial turnover in vivo. In vitro, Lgr5-2A-DTR SI organoids are unable to establish or survive when Lgr5+ ISCs are continuously eliminated when DT is in the media. However, transient exposure to DT at the start of culture allows organoids to form, and the rate of outgrowth reduces with increasing length of DT presence. Our results indicate that intestinal homeostasis requires a constant pool of Lgr5+ ISCs, which is supplied by rapidly reprogrammed non-Lgr5+ crypt populations when pre-existing Lgr5+ ISCs are ablated.
Project description:Mutations in APC or β-catenin that cause aberrant activation of Wnt signaling are responsible for the initiation of colorectal tumor development. LGR5 is specifically expressed in stem cells of the intestine, stomach and hair follicle, and plays essential roles in maintaining tissue homeostasis. LGR5-positive stem cells have been shown to be responsible for the intestinal adenoma initiated by some mutations in APC . Furthermore, it has recently been reported that Lgr5, which is associated with the Frizzled/Lrp Wnt receptor complex, interacts with R-spondins and thereby activates Wnt signaling. However, the function of LGR5 in colorectal tumorigenesis has been unclear. Here we show that LGR5 is required for the tumorigenicity of colorectal cancer cells. We also show that the transcription factor GATA6 directly enhances the expression of LGR5. DLD1 cells were infected with a lentivirus expressing an shRNA targeting GATA6 or LGR5.
Project description:SIRT6, the sixth member of sirtuin family proteins, has been identified as a crucial regulator in multiple molecular pathways related to aging, including genome stability, DNA damage repair, telomere maintenance and inflammation. However, the exact roles of SIRT6 during mammalian oocyte meiosis have not yet fully clarified. Here, we investigated the critical events during porcine oocyte meiotic maturation with the treatment of SIRT6 specific inhibitor SIRT6-IN-1. We found that SIRT6 inhibition resulted in oocyte meiotic failure by displaying the poor expansion of cumulus cells and reduced rate of polar body extrusion. Meanwhile, the compromised spindle assembly, chromosome alignment and actin dynamics were also observed in SIRT6-inhibited oocytes. Moreover, inhibition of SIRT6 led to the defective cytoplasmic maturation by showing the abnormal distribution of cortical granules and their component ovastacin. Notably, we identified that expression of genes related to oocyte meiosis, oxidative phosphorylation and cellular senescence was remarkably altered in SIRT6-inhibited oocytes by transcriptome analysis, and validated that the meiotic defects caused by SIRT6 inhibition resulted from the excessive ROS-induced early apoptosis in oocytes. Taken together, our findings demonstrate that SIRT6 promotes the porcine oocyte meiotic maturation via maintaining the organelle dynamics.