title: Microbiota matures colonic epithelium through a coordinated induction of cell cycle-related proteins in gnotobiotic rat.
abstract: Previous studies have suggested that intestinal microbiota modulates colonic epithelium renewal. The objective of our work was to study the effects of microbiota on colonic epithelium structure and cell cycle-related proteins by using gnotobiotic rats. Colonic crypts and amount of cell cycle-related proteins were compared between germ-free (GF), conventional (CV), and conventionalized rats by histochemistry and Western blot. Ki67 and proliferating cell nuclear antigen (PCNA) were used as surrogates for proliferative cells; p21(cip1) and p27(kip1) were markers of cell cycle arrest; anti- and proapoptotic proteins, Bcl2 and Bax, respectively, were also studied. We observed 40% increase of the crypt proliferative area 2 days after inoculation of GF rats with a complex microbiota. This recruitment of proliferative cells may account for the 30% increase of crypt depth observed between CV and GF rats. The hyperproliferative boost induced by microbiota was compensated by a fourfold increase of p21(cip1) and p27(kip1) involved in cell cycle arrest and a 30% drop of antiapoptotic Bcl2 protein while Bax was unchanged. Inductions of p21(cip1), p27(kip1), and PCNA protein were not paralleled by an increase of the corresponding mRNA. We also showed that p21(cip1) induction by microbiota was partially restored by Bacteroides thetaiotaomicron, Ruminococcus gnavus, and Clostridium paraputrificum. Colonization of the colon by a complex microbiota increases the crypt depth of colon epithelium. This event takes place in conjunction with a multistep process: a hyperproliferative boost accompanied by compensatory events as induction of p21(cip1) and p27(kip1) and decrease of Bcl2.
authors.affiliation: Institut National de la Recherche Agronomique, MICALIS, UMR, Pôle Ecosystèmes, Jouy-en-Josas, France. claire.cherbuy@jouy.inra.fr
authors.forename: Claire
authors.initials: C
authors.lastname: Cherbuy
authors.forename: Edith
authors.initials: E
authors.lastname: Honvo-Houeto
authors.forename: Aurélia
authors.initials: A
authors.lastname: Bruneau
authors.forename: Chantal
authors.initials: C
authors.lastname: Bridonneau
authors.forename: Camille
authors.initials: C
authors.lastname: Mayeur
authors.forename: Pierre-Henri
authors.initials: PH
authors.lastname: Duée
authors.forename: Philippe
authors.initials: P
authors.lastname: Langella
authors.forename: Muriel
authors.initials: M
authors.lastname: Thomas
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D049109:Cell Proliferation; D003106:Colon / Q000254:growth & development* / Q000378:metabolism* / Q000382:microbiology / Q000502:physiology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D005856:Germ-Free Life; D006651:Histocytochemistry; D007413:Intestinal Mucosa / Q000254:growth & development* / Q000378:metabolism* / Q000382:microbiology / Q000502:physiology; D008297:Male; D054892:Metagenome; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D019253:Proto-Oncogene Proteins c-bcl-2; D050760:Cyclin-Dependent Kinase Inhibitor p27