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The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. It is currently believed that four to six crypt stem cells reside at the +4 position immediately above the Paneth cells in the small intestine; colon stem cells remain undefined. Lgr5 (leucine-rich-repeat-containing G-protein-coupled receptor 5, also known as Gpr49) was(More)
Traffic of MHC molecules dictates the source of peptides that are presented to T cells. The intracellular distribution of MHC class I and class II molecules reflects the dichotomy in presentation of antigen from endogenous and exogenous origin, respectively. In human B lymphoblastoid cells, class I molecules are present in compartments constituting the(More)
The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. We have recently demonstrated the presence of about six cycling Lgr5(+) stem cells at the bottoms of small-intestinal crypts. Here we describe the establishment of long-term culture conditions under which single crypts undergo multiple crypt fission events, while(More)
The LKB1 gene encodes a serine/threonine kinase that is mutated in the Peutz-Jeghers cancer syndrome. LKB1 is homologous to the Par-4 polarity genes in C. elegans and D. melanogaster. We have previously reported the identification and characterization of an LKB1-specific adaptor protein, STRAD, which activates LKB1 and translocates it from nucleus to(More)
Protein localization to the TGN was investigated by examining the subcellular distribution of chimeric proteins in which the cytoplasmic and/or transmembrane domains of the TGN protein, TGN38, were substituted for the analogous domains of the plasma membrane protein, Tac. Using immunofluorescence and immunoelectron microscopy, the COOH-terminal cytoplasmic(More)
The adult stem cell marker Lgr5 and its relative Lgr4 are often co-expressed in Wnt-driven proliferative compartments. We find that conditional deletion of both genes in the mouse gut impairs Wnt target gene expression and results in the rapid demise of intestinal crypts, thus phenocopying Wnt pathway inhibition. Mass spectrometry demonstrates that Lgr4 and(More)
M. tuberculosis and M. leprae are considered to be prototypical intracellular pathogens that have evolved strategies to enable growth in the intracellular phagosomes. In contrast, we show that lysosomes rapidly fuse with the virulent M. tuberculosis- and M. leprae-containing phagosomes of human monocyte-derived dendritic cells and macrophages. After 2 days,(More)
The correlation between the intracellular Ca2+ concentration ([Ca2+]i) and membrane potential in monolayers of density-arrested normal rat kidney (NRK) fibroblasts was investigated. Using the fluorescent probe Fura-2, spontaneous repetitive spike-like increases in [Ca2+]i (Ca2+ spikes) were observed that were synchronised throughout the entire monolayer.(More)
The mammalian endopeptidase, furin, is predominantly localized to the trans-Golgi network (TGN) at steady state. The localization of furin to this compartment seems to be the result of a dynamic process in which the protein undergoes cycling between the TGN and the plasma membrane. Both TGN localization and internalization from the plasma membrane are(More)
Cytotoxic T lymphocytes (CTL) contain granules that are exocytosed during specific interaction with target cells (TC). In this process, the granule contents, including the lethal protein perforin, as well as granzymes, a family of serine esterases, are delivered to the TC. Information regarding the routing of these proteins towards the granule and their(More)