Selection of multipotent stem cells during morphogenesis of small intestinal crypts of Lieberkuehn is perturbed by stimulation of Lef-1/β-catenin signaling

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Item Type:	Article
Title:	Selection of multipotent stem cells during morphogenesis of small intestinal crypts of Lieberkuehn is perturbed by stimulation of Lef-1/β-catenin signaling
Creators Name:	Wong, M.H., Huelsken, J., Birchmeier, W. and Gordon, J.I.
Abstract:	Studies of chimeric mice have disclosed that the stem cell hierarchy in the small intestinal epithelium is established during formation of its proliferative units (crypts of Lieberkuehn). This process involves a selection among several multipotential progenitors so that ultimately only one survives to supply descendants to the fully formed crypt. In this report, we examine the hypothesis that the level of {beta}-catenin ({beta}-cat)-mediated signaling is an important factor regulating this stem cell selection. In the canonical Wnt signaling pathway, {beta}-catenin can partner with Lef-1/Tcf high mobility group (HMG) box transcription factors to control gene expression. Both Lef-1 and Tcf-4 mRNAs are produced in the fetal mouse small intestine. Tcf-4 expression is sustained, whereas Lef-1 levels fall as crypt formation is completed during the first two postnatal weeks. A Tcf-4 gene knockout is known to block intestinal epithelial proliferation in late fetal life. Therefore, to test the hypothesis, we enhanced {beta}-catenin signaling in a chimeric mouse model in which the stem cell selection could be monitored. A fusion protein containing the HMG box domain of Lef-1 linked to the trans-activation domain of {beta}-catenin (Lef-1/{beta}-cat) was constructed to promote direct stimulation of signaling without being retained in the cytoplasm through interactions with E-cadherin and Apc/Axin. Lef-1/{beta}-cat was expressed in 129/Sv embryonic stem cell-derived small intestinal epithelial progenitors present in developing B6-ROSA26↔129/Sv chimeras. Lef-1/{beta}-cat stimulated expression of a known {beta}-catenin target (E-cadherin), suppressed expression of Apc and Axin, and induced apoptosis in 129/Sv but not in neighboring B6-ROSA26 epithelial cells. This apoptotic response was not associated with any detectable changes in cell division within the Lef-1/{beta}-cat-expressing epithelium. By the time crypt development was completed, all 129/Sv epithelial cells were lost. These results indicate that developmental changes in {beta}-catenin-mediated signaling can play an important role in establishing a stem cell hierarchy during crypt morphogenesis.
Keywords:	Adenomatous Polyposis Coli Protein, B-Lymphocytes, Base Sequence, Beta Catenin, Cadherins, Cell Line, Chimera, Cyclooxygenase 2, Cytoskeletal Proteins, DNA-Binding Proteins, DNA Primers, Genotype, Hematopoietic Stem Cells, Intestinal Mucosa, Isoenzymes, Lymphoid Enhancer-Binding Factor 1, Membrane Proteins, Molecular Cloning, Morphogenesis, Prostaglandin-Endoperoxide Synthases, Proteins, Recombinant Fusion Proteins, Repressor Proteins, Restriction Mapping, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Trans-Activators, Transcription Factors, Transfection, Animals, Mice
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	277
Number:	18
Page Range:	15843-15850
Date:	3 May 2002
Official Publication:	https://doi.org/10.1074/jbc.M200184200
PubMed:	View item in PubMed

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