title: Beta1 integrin deletion from the basal compartment of the mammary epithelium affects stem cells.
abstract: The mammary gland epithelium comprises two major cell types: basal and luminal. Basal cells interact directly with the extracellular matrix (ECM) and express higher levels of the ECM receptors, integrins, than luminal cells. We show that deletion of beta1 integrin from basal cells abolishes the regenerative potential of the mammary epithelium and affects mammary gland development. The mutant epithelium was characterized by an abnormal ductal branching pattern and aberrant morphogenesis in pregnancy, although at the end of gestation, the secretory alveoli developed from beta1 integrin-positive progenitors. Lack of beta1 integrin altered the orientation of the basal-cell division axis and in mutant epithelium, in contrast to control tissue, the progeny of beta1 integrin-null basal cells, identified by a genetic marker, was found in the luminal compartment. These results reveal, for the first time, the essential role of the basal mammary epithelial cell-ECM interactions mediated by beta1 integrins in the maintenance of a functional stem cell population, mammary morphogenesis and segregation of the two major mammary cell lineages.
authors.affiliation: Institut Curie, Centre de Recherche, Centre National de la Recherche Scientifique UMR144, 26 rue d'Ulm, 75248 Paris cedex 05, France.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Taddei
authors.forename: Marie-Ange
authors.initials: MA
authors.lastname: Deugnier
authors.forename: Marisa M
authors.initials: MM
authors.lastname: Faraldo
authors.forename: Valérie
authors.initials: V
authors.lastname: Petit
authors.forename: Daniel
authors.initials: D
authors.lastname: Bouvard
authors.forename: Daniel
authors.initials: D
authors.lastname: Medina
authors.forename: Reinhard
authors.initials: R
authors.lastname: Fässler
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Thiery
authors.forename: Marina A
authors.initials: MA
authors.lastname: Glukhova
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000378:metabolism / Q000473:pathology*; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D017353:Gene Deletion; D019012:Integrin beta1 / Q000235:genetics* / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D011247:Pregnancy; D013234:Stem Cells / Q000166:cytology*
chemical_list: D019012:Integrin beta1