Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of mouse model of intestinal polyposis PTEN-deficient mutant reveals intestinal stem cells initiate intestinal polyposis

ABSTRACT: 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.

ORGANISM(S): Mus musculus

SUBMITTER: Linheng Li

PROVIDER: E-GEOD-6078 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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:Background & Aims: Hierarchical organization of intestine relies on their stem cells by self-renew and producing committed progenitors. Although signals like Wnt are known to animate the continued renewal by maintaining intestinal stem cells (ISCs) activity, molecular mechanisms especially E3 ubiquitin ligases that modulate ISCs ‘stemness’ and supportive niche have not been well understood. Here, we investigated the role of Cullin 4B (Cul4b) in regulating ISC functions. Methods: We generated mice with intestinal epithelial-specific disruption of Cul4b (pVillin-cre; Cul4bfn/Y), inducible disruption of Cul4b (Lgr5-creERT2; Cul4bfn/Y, CAG-creERT2; Cul4bfn/Y) and their control (Cul4bfn/Y). Intestinal tissues were analyzed by histology, immunofluorescence, RNA sequencing and mass spectrum. Intestinal organoids deprived from mice with pVillin-Cre; Cul4bfn/Y, Lgr5-Cre; Cul4bfn/Y, Tg-Cul4b and their controls were used in assays to measure intestinal self-renewal, proliferation and differentiation. Wnt signaling and intestinal markers were analyzed by immunofluorescence and immunoblot assays. Differential proteins upon Cul4b ablation or Cul4b-interacting proteins were identified by mass spectrometry. Results: Cul4b specifically located at ISCs zone. Block of Cul4b impaired intestinal homeostasis maintenance by reduced self-renewal and proliferation. Transcriptome analysis revealed that Cul4b-null intestine lose ISC characterization and showed disturbed ISC niche. Mechanistically, reactivated Wnt pathway could recover intestinal dysfunction of Cul4b knockout mice. Analysis of differential total and ubiquitylated proteins uncovered the novel targeting substrate of Cullin-Ring ubiquitin ligase 4b (CRL4b), immunity-related GTPase family M member 1 (Irgm1) in intestine. Decreased Irgm1 rescued abnormally interferon signaling, overemphasized autophagy and downstream phosphate proteins in Cul4b knockout mice. Conclusion: We conclude that Cul4b is essential for ISC self-renewal and Paneth cell function by targeting Irgm1 and modulating Wnt signaling. Our results demonstrate that Cul4b is a novel ISC stemness and niche regulator.

Dataset Information

Transcription profiling of mouse model of intestinal polyposis PTEN-deficient mutant reveals intestinal stem cells initiate intestinal polyposis

Publications

PTEN-deficient intestinal stem cells initiate intestinal polyposis.

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