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 β-catenin. Akt phosphorylates β-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 β-catenin.

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We are grateful to B. Neaves and R. Krumlauf for scientific support. We thank H. Okano for providing anti-Musashi1 (14-H1) and A. Ouellette for anti-cryptdin; S. Peck and G. Yang for comments on the manuscript; D. di Natale for assistance on manuscript editing; P. Kulesa and D. Stark for imaging assistance; C. Seidel, K. Zueckert-Gaudenz and M. Coleman for assistance in microarray analysis; H. Marshall for technology support and J. Chen for assistance in statistical analysis. L. Li is supported in part by research grant 5-FY05-31 from the March of Dimes Birth Defects Foundation, by grant R01 DK070001 from the National Institute of Diabetes and Digestive and Kidney Diseases and by the Stowers Institute for Medical Research.

Author information


  1. Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.

    • Xi C He
    • , Tong Yin
    • , Justin C Grindley
    • , Toshiro Sato
    • , Kimberly S Porter-Westpfahl
    • , Mark Hembree
    • , Teri Johnson
    • , Leanne M Wiedemann
    •  & Linheng Li
  2. Institute for Systems Biology, Seattle, Washington 98103, USA.

    • Qiang Tian
    •  & Leroy Hood
  3. Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, USA.

    • W Andy Tao
  4. Department of Medicine and Microbiology/Immunology, Division of Gastroenterology, Northwestern University Medical School, Chicago, Illinois 60611, USA.

    • Raminarao Dirisina
    •  & Terrence A Barrett
  5. Department of Pathology and Laboratory Medicine, Kansas University Medical Center, Kansas City, Kansas 66160, USA.

    • Leanne M Wiedemann
    •  & Linheng Li
  6. Department of Molecular and Medical Pharmacology, University of California, Los Angeles, School of Medicine, Los Angeles, California 90095, USA.

    • Hong Wu


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X.C.H., J.C.G. and L.L. designed the research; X.C.H., T.Y., T.S. and J.C.G. performed the research; Q.T., W.A.T. and L.H. performed the mass spectrometry; R.D., K.S.P-W., M.H., T.J. and T.A.B. provided technical support; H.W. contributed critical reagents; J.C.G., L.M.W. and L.L. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Linheng Li.

Supplementary information

PDF files

  1. 1.

    Supplementary Fig. 1

    Comparison of expression patterns of p-PTEN, p-Akt, 14-3-3ζ, pGSK3β and Musashi1.

  2. 2.

    Supplementary Fig. 2

    Detection of Musashi1 expression using an antibody to Musashi1 (clone 14H1).

  3. 3.

    Supplementary Fig. 3

    Cluster of Musashi1+ cells detected at the initiation site of crypt budding or crypt fission in PTEN mutants.

  4. 4.

    Supplementary Fig. 4

    Comparison of expression patterns of pβ-cat-Ser552, Top-Gal, p27kip1 and cyclin D1.

  5. 5.

    Supplementary Fig. 5

    Distribution of cells with pβ-cat-Ser552.

  6. 6.

    Supplementary Methods


  1. 1.

    Supplementary Video 1

    PTEN-deficient stem cells initiate crypt fission. Crypts were dissociated from the polyp region of PTEN mutant intestine. Whole-mount staining was performed using two antibodies: anti-β-cat-S552 (green) to recognize stem cells (normal or abnormal) and anti-cryptdin (red) to recognize Paneth cells. One β-cat-S552+ cell was located just above the Paneth cells in the proposed stem cell position; the other dividing β-cat-S552+ cell was found at the tip of the ridge formed between two dividing crypts.

  2. 2.

    Supplementary Video 2

    PTEN-deficient stem cells initiate crypt budding. Crypts were dissociated from the polyp region of PTEN mutant intestine. Whole-mount staining was performed using two antibodies: anti-β-cat-S552 (green) to recognize stem cells (normal or abnormal) and anti-cryptdin (red) to recognize Paneth cells. One β-cat-S552+ cell was located just above the Paneth cells in the proposed stem cell position; a cluster of β-cat-S552+ cells was found at the junction between a budding crypt and the edge of the original crypt.

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