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PTEN-deficient intestinal stem cells initiate intestinal polyposis.

ABSTRACT: Intestinal polyposis, a precancerous neoplasia, results primarily from an abnormal increase in the number of crypts, which contain intestinal stem cells (ISCs). In mice, widespread deletion of the tumor suppressor Phosphatase and tensin homolog (PTEN) generates hamartomatous intestinal polyps with epithelial and stromal involvement. Using this model, we have established the relationship between stem cells and polyp and tumor formation. PTEN helps govern the proliferation rate and number of ISCs and loss of PTEN results in an excess of ISCs. In PTEN-deficient mice, excess ISCs initiate de novo crypt formation and crypt fission, recapitulating crypt production in fetal and neonatal intestine. The PTEN-Akt pathway probably governs stem cell activation by helping control nuclear localization of the Wnt pathway effector beta-catenin. Akt phosphorylates beta-catenin at Ser552, resulting in a nuclear-localized form in ISCs. Our observations show that intestinal polyposis is initiated by PTEN-deficient ISCs that undergo excessive proliferation driven by Akt activation and nuclear localization of beta-catenin.

SUBMITTER: He XC

PROVIDER: S-EPMC4681524 | biostudies-literature | 2007 Feb

REPOSITORIES: biostudies-literature

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PTEN-deficient intestinal stem cells initiate intestinal polyposis.

He Xi C XC Yin Tong T Grindley Justin C JC Tian Qiang Q Sato Toshiro T Tao W Andy WA Dirisina Raminarao R Porter-Westpfahl Kimberly S KS Hembree Mark M Johnson Teri T Wiedemann Leanne M LM Barrett Terrence A TA Hood Leroy L Wu Hong H Li Linheng L

Nature genetics 20070121 2

Intestinal polyposis, a precancerous neoplasia, results primarily from an abnormal increase in the number of crypts, which contain intestinal stem cells (ISCs). In mice, widespread deletion of the tumor suppressor Phosphatase and tensin homolog (PTEN) generates hamartomatous intestinal polyps with epithelial and stromal involvement. Using this model, we have established the relationship between stem cells and polyp and tumor formation. PTEN helps govern the proliferation rate and number of ISCs ...[more]

PMID: 17237784

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Project description:Intestinal polyposis, a precancerous neoplasia, results primarily from an abnormal increase in the number of crypts. Crypts contain intestinal stem cells (ISCs). Thus intestinal polyposis provides an ideal condition for studying stem cell involvement in polyp/tumor formation. Using a conditional knock-out mouse model, we found that the tumor suppressor Phosphatase of Tension homolog (PTEN) governs the proliferation rate and number of ISCs and loss of PTEN results in an excess of ISCs. In PTEN mutants, excess ISCs initiate de-novo crypt formation and crypt fission, recapitulating crypt production in fetal/neonatal intestine. Microarray studies were used to profile the changes in gene expression that occurred when PTEN was knocked out in the intestine. Experiment Overall Design: A conditional PTEN mutant allele [Groszer, M. et al. Negative regulation of neural stem/progenitor cell proliferation by the Pten tumor suppressor gene in vivo. Science 294, 2186-2189 (2001).] was combined with in interferon inducible Mx1-Cre [Kuhn, R., Schwenk, F., Aguet, M. & Rajewsky, K. Inducible gene targeting in mice. Science 269, 1427-1429 (1995).] to enable PTEN to be deleted from the intestine by administration of polyinosinicâ??polycytidylic acid (Poly I:C). PolyI:C was administered at weaning (every other day, five times total) to three PTEN mutant (Mx1-Cre positive:PTENfx/fx) and two control (Mx1-Cre negative:PTENfx/+) animals. Intestinal polyps (from PTEN mutants) and equivalent regions of intestine (from controls) were isolated 30 days after the final polyI:C injection. Microarray analysis compared the gene expression profiles of PTEN mutant polyps and control intestines. Genes were considered up-regulated or down-regulated if all of the following conditions were met: 1) There was at least a two-fold change in the average probe signal measured between controls and mutants; 2) There was no overlap between the range of mutant and control data; and 3) The control mean was outside the 95% confidence interval of the PTEN-mutant mean.

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PTEN-deficient intestinal stem cells initiate intestinal polyposis.

Publications

PTEN-deficient intestinal stem cells initiate intestinal polyposis.

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