title: Indian hedgehog regulates intestinal stem cell fate through epithelial-mesenchymal interactions during development.
abstract: OBJECTIVE
  Intestinal stem cells (ISCs) are regulated by the mesenchymal environment via physical interaction and diffusible factors. We examined the role of Indian hedgehog (Ihh) in mesenchymal organization and the mechanisms by which perturbations in epithelial-mesenchymal interactions affect ISC fate.
  
  
  METHODS
  We generated mice with intestinal epithelial-specific disruption of Ihh. Gross and microscopic anatomical changes were determined using histologic, immunohistochemical, and in situ hybridization analyses. Molecular mechanisms were elucidated by expression profiling and in vitro analyses.
  
  
  RESULTS
  Deletion of intestinal epithelial Ihh disrupted the intestinal mesenchymal architecture, demonstrated by loss of the muscularis mucosae, deterioration of the extracellular matrix, and reductions in numbers of crypt myofibroblasts. Concurrently, the epithelial compartment had increased Wnt signaling, disturbed crypt polarity and architecture, defective enterocyte differentiation, and increased and ectopic proliferation that was accompanied by increased numbers of ISCs. Mechanistic studies revealed that Hh inhibition deregulates bone morphogenetic protein signaling, increases matrix metalloproteinase levels, and disrupts extracellular matrix proteins, fostering a proliferative environment for ISCs and progenitor cells.
  
  
  CONCLUSIONS
  Ihh regulates ISC self-renewal and differentiation. Intestinal epithelial Ihh signals to the mesenchymal compartment to regulate formation and proliferation of mesenchymal cells, which in turn affect epithelial proliferation and differentiation. These findings provide a basis for analyses of the role of the muscularis mucosae in ISC regulation.
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California 94143, USA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Kosinski
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Stange
authors.forename: Chuanrui
authors.initials: C
authors.lastname: Xu
authors.forename: Annie Sy
authors.initials: AS
authors.lastname: Chan
authors.forename: Coral
authors.initials: C
authors.lastname: Ho
authors.forename: Siu Tsan
authors.initials: ST
authors.lastname: Yuen
authors.forename: Randy C
authors.initials: RC
authors.lastname: Mifflin
authors.forename: Don W
authors.initials: DW
authors.lastname: Powell
authors.forename: Hans
authors.initials: H
authors.lastname: Clevers
authors.forename: Suet Yi
authors.initials: SY
authors.lastname: Leung
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D002450:Cell Communication; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation; D003092:Colitis / Q000378:metabolism / Q000473:pathology; D003106:Colon / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D005838:Genotype; D053823:Hedgehog Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D019426:Integrases / Q000235:genetics; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008648:Mesoderm / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics; D019899:Paracrine Communication; D010641:Phenotype; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism* / Q000473:pathology; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
chemical_list: C495267:CTNNB1 protein, mouse; D016326:Extracellular Matrix Proteins; D053823:Hedgehog Proteins; D008840:Microfilament Proteins; D051153:Wnt Proteins; D051176:beta Catenin; C514061:ihh protein, mouse; C026615:villin; C045073:Cre recombinase; D019426:Integrases