Lgr4基因在肠自稳态维持及肠炎中的功能研究
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摘要
Wnt信号通路在肠上皮细胞的增殖与分化过程中起着重要的调控作用,Lgr4作为一个经典的七次跨膜蛋白,是新鉴定出来的Rspondin蛋白家族的受体之一,并能够激活Wnt信号通路。但是Lgr4在动物体内是如何通过Wnt信号通路调节肠上皮的自稳态维持目前仍然不清楚。利用gene-trap小鼠模型,我们发现Lgr4主要在肠上皮隐窝中表达并且在小肠隐窝底部潘氏细胞(Paneth细胞)中表达较高。通过对Lgr4基因敲除小鼠肠组织学分析发现其Paneth细胞及Lgr5肠干细胞数目大大减少,Bmil肠干细胞数目也显著降低了。利用DSS诱导肠炎性疾病(Inflammatory bowel diseas)模型,Lgr4基因敲除鼠相对于野生型小鼠表现出剧烈的炎症反应及高致死率。对其分子机理进行研究发现,Lgr4基因敲除鼠中Wnt/β-catenin信号通路显著下调导致其肠上皮细胞在炎症损伤过程修复缺陷,最终引起肠上皮屏障被严重破坏。通过与APCmin小鼠杂交或者注射GSK3β抑制剂SB216763在Lgr4基因敲除鼠中激活Wnt信号通路,Paneth细胞的数目得到了部分的回复并且DSS诱导的炎症症状明显减轻,存活率也得到了显著的提高。综上所述,我们的研究表明,Lgr4在肠上皮自稳态维持过程中有着重要的作用,并且通过调节Wnt/β-catenin信号通路促进肠上皮在肠炎过程中的损伤修复。
The proliferation and differentiation of epithelial cells in the intestine are tightly regulated by Wnt signaling pathway. Lgr4is one of the newly identified R-Spondinl receptor potentiate Wnt signaling. However, how Lgr4regulates intestinal homeostasis remains elusive. By using an Lgr4gene-trap mouse strain which contains a β-gal reporter driven by endougenous Lgr4promoter we found Lgr4expresses mainly in cypts and predominantly in Paneth cells which constitute the potential niche for Lgr5positive intestinal stem cells (ISCs). Lgr4deficiency resulted in greatly reduced cell number of either Paneth cells or stem cells in the intestine. To explore the physiological role of Lgr4in intestinal inflammation, dextran sulfate sodium (DSS)-induced IBD model was employed. Intestinal inflammation was induced with DSS, followed by a recovery period. Intestinal inflammation symptoms and molecular mechanisms were examined. We found that Lgr4-/-mice exhibited dramatically higher susceptibility and mortality to DSS-induced inflammatory bowel disease (IBD) than WT mice. Mechanisim research determined downregulated Wnt/β-catenin signaling in the intestinal epithelium of Lgr4-/-mice. When Wnt/β-catenin signaling was re-activated by crossing with APCmin/+mice or by treating with a GSK-3β inhibitor, the number of Paneth cells was partially restored and the mortality caused by DSS-induced IBD was strikingly reduced in Lgr4deficient animals. Thus, Lgr4is critically involved in the maintenance of intestinal homeostasis and protection against inflammatory bowel disease through modulation of the Wnt/β-catenin signaling pathway.
引文
1. Huang, C.S., et al., Hyperplastic polyps, serrated adenomas, and the serrated polyp neoplasia pathway. Am J Gastroenterol,2004.99(11):p.2242-55.
    2. Kaser, A., S. Zeissig, and R.S. Blumberg, Inflammatory bowel disease. Annu Rev Immunol, 2010.28:p.573-621.
    3. Hill, D.A. and D. Artis, Intestinal bacteria and the regulation of immune cell homeostasis. Annu Rev Immunol,2010.28:p.623-67.
    4. Artis, D., Epithelial-cell recognition of commensal bacteria and maintenance of immune homeostasis in the gut. Nat Rev Immunol,2008.8(6):p.411-20.
    5. Hooper, L.V. and A.J. Macpherson, Immune adaptations that maintain homeostasis with the intestinal microbiota. Nat Rev Immunol,2010.10(3):p.159-69.
    6. Garrett, W.S., J.I. Gordon, and L.H. Glimcher, Homeostasis and inflammation in the intestine. Cell,2010.140(6):p.859-70.
    7. Langholz, E., et al., Colorectal cancer risk and mortality in patients with ulcerative colitis. Gastroenterology,1992.103(5):p.1444-51.
    8. Hussain, S.P., L.J. Hofseth, and C.C. Harris, Radical causes of cancer. Nat Rev Cancer,2003. 3(4):p.276-85.
    9. Karin, M. and F.R. Greten, NF-kappaB:linking inflammation and immunity to cancer development and progression. Nat Rev Immunol,2005.5(10):p.749-59.
    10. Greten, F.R., et al., IKKbeta links inflammation and tumorigenesis in a mouse model of colitis-associated cancer. Cell,2004.118(3):p.285-96.
    11. Grivennikov, S., et al., IL-6 and Stat3 are required for survival of intestinal epithelial cells and development of colitis-associated cancer. Cancer Cell,2009.15(2):p.103-13.
    12. Gregorieff, A. and H. Clevers, Wnt signaling in the intestinal epithelium:from endoderm to cancer. Genes Dev,2005.19(8):p.877-90.
    13. Sato, T., et al., Paneth cells constitute the niche for Lgr5 stem cells in intestinal crypts. Nature, 2011.469(7330):p.415-8.
    14. Rothenberg, M.E., et al., Identification of a cKit(+) colonic crypt base secretory cell that supports Lgr5(+) stem cells in mice. Gastroenterology,2012.142(5):p.1195-1205 e6.
    15. de Lau, W., et al., Peyer's patch M cells derived from Lgr5(+) stem cells require SpiB and are induced by RankL in cultured "miniguts". Mol Cell Biol,2012.32(18):p.3639-47.
    16. Barker, N., S. Bartfeld, and H. Clevers, Tissue-resident adult stem cell populations of rapidly self-renewing organs. Cell Stem Cell,2010.7(6):p.656-70.
    17. Heath, J.P., Epithelial cell migration in the intestine. Cell Biol Int,1996.20(2):p.139-46.
    18. Tumbar, T., et al., Defining the epithelial stem cell niche in skin. Science,2004.303(5656):p. 359-63.
    19. Kiel, M.J., et al., Haematopoietic stem cells do not asymmetrically segregate chromosomes or retain BrdU. Nature,2007.449(7159):p.238-42.
    20. Alison, M.R. and S. Islam, Attributes of adult stem cells. J Pathol,2009.217(2):p.144-60.
    21. Cheng, H. and C.P. Leblond, Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine. V. Unitarian Theory of the origin of the four epithelial cell types. Am J Anat,1974.141(4):p.537-61.
    22. Bjerknes, M. and H. Cheng, Clonal analysis of mouse intestinal epithelial progenitors. Gastroenterology,1999.116(1):p.7-14.
    23. Bjerknes, M. and H. Cheng, Multipotential stem cells in adult mouse gastric epithelium. Am J Physiol Gastrointest Liver Physiol,2002.283(3):p. G767-77.
    24. Bjerknes, M. and H. Cheng, The stem-cell zone of the small intestinal epithelium. IV. Effects of resecting 30% of the small intestine. Am J Anat,1981.160(1):p.93-103.
    25. Bjerknes, M. and H. Cheng, The stem-cell zone of the small intestinal epithelium. I. Evidence from Paneth cells in the adult mouse. Am J Anat,1981.160(1):p.51-63.
    26. Bjerknes, M. and H. Cheng, The stem-cell zone of the small intestinal epithelium. V. Evidence for controls over orientation of boundaries between the stem-cell zone, proliferative zone, and the maturation zone. Am J Anat,1981.160(1):p.105-12.
    27. Caimie, A.B., L.F. Lamerton, and G.G. Steel, Cell proliferation studies in the intestinal epithelium of the rat. Ⅱ. Theoretical aspects. Exp Cell Res,1965.39(2):p.539-53.
    28. Potten, C.S., Extreme sensitivity of some intestinal crypt cells to X and gamma irradiation. Nature,1977.269(5628):p.518-21.
    29. Marshman, E., C. Booth, and C.S. Potten, The intestinal epithelial stem cell. Bioessays,2002. 24(1):p.91-8.
    30. Potten, C.S., et al., The stem cells of small intestinal crypts:where are they? Cell Prolif,2009. 42(6):p.731-50.
    31. Cairns, J., Mutation selection and the natural history of cancer. Nature,1975.255(5505):p. 197-200.
    32. van de Wetering, M., et al., The beta-catenin/TCF-4 complex imposes a crypt progenitor phenotype on colorectal cancer cells. Cell,2002.111(2):p.241-50.
    33. Van der Flier, L.G., et al., The Intestinal Wnt/TCF Signature. Gastroenterology,2007.132(2): p.628-32.
    34. Carmon, K.S., et al., LGR5 interacts and cointernalizes with Wnt receptors to modulate Wnt/beta-catenin signaling. Mol Cell Biol,2012.32(11):p.2054-64.
    35. de Lau, W., et al., Lgr5 homologues associate with Wnt receptors and mediate R-spondin signalling. Nature,2011.476(7360):p.293-7.
    36. Glinka, A., et al., LGR4 and LGR5 are R-spondin receptors mediating Wnt/beta-catenin and Wnt/PCP signalling. EMBO Rep,2011.12(10):p.1055-61.
    37. Carmon, K.S., et al., R-spondins function as ligands of the orphan receptors LGR4 and LGR5 to regulate Wnt/beta-catenin signaling. Proc Natl Acad Sci U S A,2011.108(28):p.11452-7.
    38. Hao, H.X., et al., ZNRF3 promotes Wnt receptor turnover in an R-spondin-sensitive manner. Nature,2012.485(7397):p.195-200.
    39. Koo, B.K., et al., Tumour suppressor RNF43 is a stem-cell E3 ligase that induces endocytosis of Wnt receptors. Nature,2012.488(7413):p.665-9.
    40. Barker, N., et al., Identification of stem cells in small intestine and colon by marker gene Lgr5. Nature,2007.449(7165):p.1003-7.
    41. Escobar, M., et al., Intestinal epithelial stem cells do not protect their genome by asymmetric chromosome segregation. Nat Commun,2011.2:p.258.
    42. Schepers, A.G., et al., Lgr5 intestinal stem cells have high telomerase activity and randomly segregate their chromosomes. EMBO J,2011.30(6):p.1104-9.
    43. Barker, N., et al., Very long-term self-renewal of small intestine, colon, and hair follicles from cycling Lgr5+ve stem cells. Cold Spring Harb Symp Quant Biol,2008.73:p.351-6.
    44. Munoz, J., et al., The Lgr5 intestinal stem cell signature:robust expression of proposed quiescent'+4'cell markers. EMBO J,2012.31(14):p.3079-91.
    45. van der Flier, L.G., et al., Transcription factor achaete scute-like 2 controls intestinal stem cell fate. Cell,2009.136(5):p.903-12.
    46. van der Flier, L.G., et al., OLFM4 is a robust marker for stem cells in human intestine and marks a subset of colorectal cancer cells. Gastroenterology,2009.137(1):p.15-7.
    47. Koo, B.K., et al., Controlled gene expression in primary Lgr5 organoid cultures. Nat Methods, 2012.9(1):p.81-3.
    48. Barker, N., et al., Lgr5(+ve) stem cells drive self-renewal in the stomach and build long-lived gastric units in vitro. Cell Stem Cell,2010.6(1):p.25-36.
    49. Sato, T., et al., Single Lgr5 stem cells build crypt-villus structures in vitro without a mesenchymal niche. Nature,2009.459(7244):p.262-5.
    50. Durand, A., et al., Functional intestinal stem cells after Paneth cell ablation induced by the loss of transcription factor Mathl (Atohl). Proc Natl Acad Sci U S A,2012.109(23):p. 8965-70.
    51. Yui, S., et al., Functional engraftment of colon epithelium expanded in vitro from a single adult Lgr5(+) stem cell. Nat Med,2012.18(4):p.618-23.
    52. Sangiorgi, E. and M.R. Capecchi, Bmil is expressed in vivo in intestinal stem cells. Nat Genet, 2008.40(7):p.915-20.
    53. Yan, K.S., et al., The intestinal stem cell markers Bmil and Lgr5 identify two functionally distinct populations. Proc Natl Acad Sci U S A,2012.109(2):p.466-71.
    54. Montgomery, R.K., et al., Mouse telomerase reverse transcriptase (mTert) expression marks slowly cycling intestinal stem cells. Proc Natl Acad Sci U S A,2011.108(1):p.179-84.
    55. Takeda, N., et al., Interconversion between intestinal stem cell populations in distinct niches. Science,2011.334(6061):p.1420-4.
    56. Powell, A.E., et al., The pan-ErbB negative regulator Lrigl is an intestinal stem cell marker that functions as a tumor suppressor. Cell,2012.149(1):p.146-58.
    57. Carlone, D.L. and D.T. Breault, Tales from the crypt:the expanding role of slow cycling intestinal stem cells. Cell Stem Cell,2012.10(1):p.2-4.
    58. Li, L. and H. Clevers, Coexistence of quiescent and active adult stem cells in mammals. Science,2010.327(5965):p.542-5.
    59. Wong, V.W., et al., Lrigl controls intestinal stem-cell homeostasis by negative regulation of ErbB signalling. Nat Cell Biol,2012.14(4):p.401-8.
    60. Itzkovitz, S., et al., Single-molecule transcript counting of stem-cell markers in the mouse intestine. Nat Cell Biol,2012.14(1):p.106-14.
    61. van Es, J.H., et al., Dll1+secretory progenitor cells revert to stem cells upon crypt damage. Nat Cell Biol,2012.14(10):p.1099-104.
    62. Logan, C.Y. and R. Nusse, The Wnt signaling pathway in development and disease. Annu Rev Cell Dev Biol,2004.20:p.781-810.
    63. Veeman, M.T., J.D. Axelrod, and R.T. Moon, A second canon. Functions and mechanisms of beta-catenin-independent Wnt signaling. Dev Cell,2003.5(3):p.367-77.
    64. De Calisto, J., et al., Essential role of non-canonical Wnt signalling in neural crest migration. Development,2005.132(11):p.2587-97.
    65. Katanaev, V.L., et al., Trimeric G protein-dependent frizzled signaling in Drosophila. Cell, 2005.120(1):p.111-22.
    66. Liu, X., J.S. Rubin, and A.R. Kimmel, Rapid, Wnt-induced changes in GSK3beta associations that regulate beta-catenin stabilization are mediated by Galpha proteins. Curr Biol,2005. 15(22):p.1989-97.
    67. Maye, P., et al., Multiple mechanisms for Wntll-mediated repression of the canonical Wnt signaling pathway. J Biol Chem,2004.279(23):p.24659-65.
    68. Nishisho, I., et al., Mutations of chromosome 5q21 genes in FAP and colorectal cancer patients. Science,1991.253(5020):p.665-9.
    69. Groden, J., et al., Identification and characterization of the familial adenomatous polyposis coligene. Cell,1991.66(3):p.589-600.
    70. Miyoshi, Y., et al., Germ-line mutations of the APC gene in 53 familial adenomatous polyposis patients. Proc Natl Acad Sci U S A,1992.89(10):p.4452-6.
    71. Powell, S.M., et al., APC mutations occur early during colorectal tumorigenesis. Nature,1992. 359(6392):p.235-7.
    72. Levy, D.B., et al., Inactivation of both APC alleles in human and mouse tumors. Cancer Res, 1994.54(22):p.5953-8.
    73. Ichii, S., et al., Inactivation of both APC alleles in an early stage of colon adenomas in a patient with familial adenomatous polyposis (FAP). Hum Mol Genet,1992.1(6):p.387-90.
    74. Smith, K.J., et al., The APC gene product in normal and tumor cells. Proc Natl Acad Sci U S A,1993.90(7):p.2846-50.
    75. Moser, A.R., H.C. Pitot, and W.F. Dove, A dominant mutation that predisposes to multiple intestinal neoplasia in the mouse. Science,1990.247(4940):p.322-4.
    76. Su, L.K., et al., Multiple intestinal neoplasia caused by a mutation in the murine homolog of the APC gene. Science,1992.256(5057):p.668-70.
    77. Yamada, Y., et al., Microadenomatous lesions involving loss of Apc heterozygosity in the colon of adult Apc(Min/+) mice. Cancer Res,2002.62(22):p.6367-70.
    78. Gregorieff, A., et al., Expression pattern of Wnt signaling components in the adult intestine. Gastroenterology,2005.129(2):p.626-38.
    79. Hao, X.P., et al., Beta-catenin expression is altered in human colonic aberrant crypt foci. Cancer Res,2001.61(22):p.8085-8.
    80. Inomata, M., et al., Alteration of beta-catenin expression in colonic epithelial cells of familial adenomatous polyposis patients. Cancer Res,1996.56(9):p.2213-7.
    81. Ilyas, M., et al., Beta-catenin mutations in cell lines established from human colorectal cancers. Proc Natl Acad Sci U S A,1997.94(19):p.10330-4.
    82. Samowitz, W.S., et al., Beta-catenin mutations are more frequent in small colorectal adenomas than in larger adenomas and invasive carcinomas. Cancer Res,1999.59(7):p. 1442-4.
    83. Peifer, M., Beta-catenin as oncogene:the smoking gun. Science,1997.275(5307):p.1752-3.
    84. Brabletz, T., A. Jung, and T. Kirchner, Beta-catenin and the morphogenesis of colorectal cancer. Virchows Arch,2002.441(1):p.1-11.
    85. Fodde, R., R. Smits, and H. Clevers, APC, signal transduction and genetic instability in colorectal cancer. Nat Rev Cancer,2001.1(1):p.55-67.
    86. Fearon, E.R. and B. Vogelstein, A genetic model for colorectal tumorigenesis. Cell,1990. 61(5):p.759-67.
    87. Hsu, S.Y., S.G. Liang, and A.J. Hsueh, Characterization of two LGR genes homologous to gonadotropin and thyrotropin receptors with extracellular leucine-rich repeats and a G protein-coupled, seven-transmembrane region. Mol Endocrinol,1998.12(12):p.1830-45.
    88. Hsu, S.Y., et al., The three subfamilies of leucine-rich repeat-containing G protein-coupled receptors (LGR):identification of LGR6 and LGR7 and the signaling mechanism for LGR7. Mol Endocrinol,2000.14(8):p.1257-71.
    89. Nothacker, H.P. and C.J. Grimmelikhuijzen, Molecular cloning of a novel, putative G protein-coupled receptor from sea anemones structurally related to members of the FSH, TSH, LH/CG receptor family from mammals. Biochem Biophys Res Commun,1993.197(3):p. 1062-9.
    90. Herpin, A., et al., Molecular characterization of a new leucine-rich repeat-containing G protein-coupled receptor from a bivalve mollusc:evolutionary implications. Biochim Biophys Acta,2004.1680(3):p.137-44.
    91. Tensen, C.P., et al., A G protein-coupled receptor with low density lipoprotein-binding motifs suggests a role for lipoproteins in G-linked signal transduction. Proc Natl Acad Sci U S A, 1994.91(11):p.4816-20.
    92. Kudo, M., et al., The nematode leucine-rich repeat-containing, G protein-coupled receptor (LGR) protein homologous to vertebrate gonadotropin and thyrotropin receptors is constitutively active in mammalian cells. Mol Endocrinol,2000.14(2):p.272-84.
    93. Hauser, F., H.P. Nothacker, and C.J. Grimmelikhuijzen, Molecular cloning, genomic organization, and developmental regulation of a novel receptor from Drosophila melanogaster structurally related to members of the thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone/choriogonadotropin receptor family from mammals. J Biol Chem,1997.272(2):p.1002-10.
    94. Nishi, S., et al., Characterization of two fly LGR (leucine-rich repeat-containing, G protein-coupled receptor) proteins homologous to vertebrate glycoprotein hormone receptors: constitutive activation of wild-type fly LGR1 but not LGR2 in transfected mammalian cells. Endocrinology,2000.141(11):p.4081-90.
    95. Mazerbourg, S., et al., Leucine-rich repeat-containing, G protein-coupled receptor 4 null mice exhibit intrauterine growth retardation associated with embryonic and perinatal lethality. Mol Endocrinol,2004.18(9):p.2241-54.
    96. Van Schoore, G., et al., Expression pattern of the orphan receptor LGR4/GPR48 gene in the mouse. Histochem Cell Biol,2005.124(1):p.35-50.
    97. Leighton, P.A., et al., Defining brain wiring patterns and mechanisms through gene trapping in mice. Nature,2001.410(6825):p.174-9.
    98. Mendive, F., et al., Defective postnatal development of the male reproductive tract in LGR4 knockout mice. Dev Biol,2006.290(2):p.421-34.
    99. Li, X.Y., et al., G protein-coupled receptor 48 upregulates estrogen receptor alpha expression via cAMP/PKA signaling in the male reproductive tract. Development,2010.137(1):p.151-7.
    100. Hoshii, T., et al., LGR4 regulates the postnatal development and integrity of male reproductive tracts in mice. Biol Reprod,2007.76(2):p.303-13.
    101. Yamashita, R., et al., Defective development of the gall bladder and cystic duct in Lgr4-hypomorphic mice. Dev Dyn,2009.238(4):p.993-1000.
    102. Song, H., et al., Inactivation of G-protein-coupled receptor 48 (Gpr48/Lgr4) impairs definitive erythropoiesis at midgestation through down-regulation of the ATF4 signaling pathway. J Biol Chem,2008.283(52):p.36687-97.
    103. Weng, J., et al., Deletion of G protein-coupled receptor 48 leads to ocular anterior segment dysgenesis (ASD) through down-regulation of Pitx2. Proc Natl Acad Sci U S A,2008.105(16): p.6081-6.
    104. Luo, J., et al., Regulation of bone formation and remodeling by G-protein-coupled receptor 48. Development,2009.136(16):p.2747-56.
    105. Kato, S., et al., Leucine-rich repeat-containing G protein-coupled receptor-4 (LGR4, Gpr48) is essential for renal development in mice. Nephron Exp Nephrol,2006.104(2):p. e63-75.
    106. Kato, S., et al., Eye-open at birth phenotype with reduced kcratinocyte motility in LGR4 null mice. FEBS Lett,2007.581(24):p.4685-90.
    107. Jin, C., et al., GPR48 regulates epithelial cell proliferation and migration by activating EGFR during eyelid development. Invest Ophthalmol Vis Sci,2008.49(10):p.4245-53.
    108. Mohri, Y., et al., Impaired hair placode formation with reduced expression of hair follicle-related genes in mice lacking Lgr4. Dev Dyn,2008.237(8):p.2235-42.
    109. Luo, W., et al., Lgr4 is a key regulator of prostate development and prostate stem cell differentiation. Stem Cells,2013.
    110. Qian, Y, et al., Lgr4-mediated Wnt/beta-catenin signaling in peritubular myoid cells is essential for spermatogenesis. Development,2013.140(8):p.1751-61.
    111. Wang, J., et al., GPR48 increases mineralocorticoid receptor gene expression. J Am Soc Nephrol,2012.23(2):p.281-93.
    112. Wang, Y., et al., Lgr4 Regulates Mammary Gland Development and Stem Cell Activity through the Pluripotency Transcription Factor Sox2. Stem Cells,2013.
    113. Wang, Z., et al., GPR48-Induced keratinocyte proliferation occurs through HB-EGF mediated EGFR transactivation. FEBS Lett,2010.584(18):p.4057-62.
    114. Liu, S., et al., Lgr4 gene deficiency increases susceptibility and severity of dextran sodium sulfate-induced inflammatory bowel disease in mice. J Biol Chem,2013.288(13):p.8794-803; discussion 8804.
    115. Mustata, R.C., et al., Lgr4 is required for Paneth cell differentiation and maintenance of intestinal stem cells ex vivo. EMBO Rep,2011.12(6):p.558-64.
    116. Porter, E.M., et al., The multifaceted Paneth cell. Cell Mol Life Sci,2002.59(1):p.156-70.
    117. Weissman, I.L., Stem cells:units of development, units of regeneration, and units in evolution. Cell,2000.100(1):p.157-68.
    118. Zhu, L., et al., Prominin 1 marks intestinal stem cells that are susceptible to neoplastic transformation. Nature,2009.457(7229):p.603-7.
    119. Garabedian, E.M., et al., Examining the role of Paneth cells in the small intestine by lineage ablation in transgenic mice. J Biol Chem,1997.272(38):p.23729-40.
    120. Tian, H., et al., A reserve stem cell population in small intestine renders Lgr5-positive cells dispensable. Nature,2011.478(7368):p.255-9.
    121. Hoffman, J., et al., Wnts as essential growth factors for the adult small intestine and colon. Cell Cycle,2004.3(5):p.554-7.
    122. Korinek, V., et al., Constitutive transcriptional activation by a beta-catenin-Tcf complex in APC-/- colon carcinoma. Science,1997.275(5307):p.1784-7.
    123. Morin, P.J., et al., Activation of beta-catenin-Tcf signaling in colon cancer by mutations in beta-catenin or APC. Science,1997.275(5307):p.1787-90.
    124. van Es, J.H., et al., Wnt signalling induces maturation of Paneth cells in intestinal crypts. Nat Cell Biol,2005.7(4):p.381-6.
    125. Reya, T. and H. Clevers, Wnt signalling in stem cells and cancer. Nature,2005.434(7035):p. 843-50.
    126. Wei, K., F. Kuhnert, and C.J. Kuo, Recombinant adenovirus as a methodology for exploration of physiologic functions of growth factor pathways. J Mol Med (Berl),2008.86(2):p.161-9.
    127. Kim, K.A., et al., Mitogenic influence of human R-spondinl on the intestinal epithelium. Science,2005.309(5738):p.1256-9.
    128. Ootani, A., et al., Sustained in vitro intestinal epithelial culture within a Wnt-dependent stem cell niche. Nat Med,2009.15(6):p.701-6.
    129. Podolsky, D.K., Inflammatory bowel disease. N Engl J Med,2002.347(6):p.417-29.
    130. Strober, W., I.J. Fuss, and R.S. Blumberg, The immunology of mucosal models of inflammation. Annu Rev Immunol,2002.20:p.495-549.
    131. Mizoguchi, A., E. Mizoguchi, and A.K. Bhan, Immune networks in animal models of inflammatory bowel disease. Inflamm Bowel Dis,2003.9(4):p.246-59.
    132. Elson, C.O., et al., Experimental models of inflammatory bowel disease. Gastroenterology, 1995.109(4):p.1344-67.
    133. Korinek, V., et al., Depletion of epithelial stem-cell compartments in the small intestine of mice lacking Tcf-4. Nat Genet,1998.19(4):p.379-83.
    134. Cadwell, K., et al., A key role for autophagy and the autophagy gene Atgl6ll in mouse and human intestinal Paneth cells. Nature,2008.456(7219):p.259-63.
    135. Kaser, A., et al., XBPI links ER stress to intestinal inflammation and confers genetic risk for human inflammatory bowel disease. Cell,2008.134(5):p.743-56.
    136. Gunther, C., et al., Caspase-8 regulates TNF-alpha-induced epithelial necroptosis and terminal ileitis. Nature,2011.477(7364):p.335-9.
    137. Medema, J.P. and L. Vermeulen, Microenvironmental regulation of stem cells in intestinal homeostasis and cancer. Nature,2011.474(7351):p.318-26.
    138. Nava, P., et al., Interferon-gamma regulates intestinal epithelial homeostasis through converging beta-catenin signaling pathways. Immunity,2010.32(3):p.392-402.
    139. Kaiser, G.C. and D.B. Polk, Tumor necrosis factor alpha regulates proliferation in a mouse intestinal cell line. Gastroenterology,1997.112(4):p.1231-40.
    140. Koch, S., et al., The Wnt antagonist Dkkl regulates intestinal epithelial homeostasis and wound repair. Gastroenterology,2011.141(1):p.259-68,268 el-8.
    141. Lee, G., et al., Phosphoinositide 3-kinase signaling mediates beta-catenin activation in intestinal epithelial stem and progenitor cells in colitis. Gastroenterology,2010.139(3):p. 869-81,881 el-9.
    142. Ashton, G.H., et al., Focal adhesion kinase is required for intestinal regeneration and tumorigenesis downstream of Wnt/c-Myc signaling. Dev Cell,2010.19(2):p.259-69.
    143. Nusse, R. and H.E. Varmus, Many tumors induced by the mouse mammary tumor virus contain a provirus integrated in the same region of the host genome. Cell,1982.31(1):p. 99-109.
    144. Nusslein-Volhard, C. and E. Wieschaus, Mutations affecting segment number and polarity in Drosophila. Nature,1980.287(5785):p.795-801.
    145. Rijsewijk, F., et al., The Drosophila homolog of the mouse mammary oncogene int-1 is identical to the segment polarity gene wingless. Cell,1987.50(4):p.649-57.
    146. Noordermeer, J., et al., dishevelled and armadillo act in the wingless signalling pathway in Drosophila. Nature,1994.367(6458):p.80-3.
    147. Peifer, M., et al., The vertebrate adhesive junction proteins beta-catenin and plakoglobin and the Drosophila segment polarity gene armadillo form a multigene family with similar properties. J Cell Biol,1992.118(3):p.681-91.
    148. Siegfried, E., T.B. Chou, and N. Perrimon, wingless signaling acts through zeste-white 3, the Drosophila homolog of glycogen synthase kinase-3, to regulate engrailed and establish cell fate. Cell,1992.71(7):p.1167-79.
    149. McMahon, A.P. and R.T. Moon, Ectopic expression of the proto-oncogene int-1 in Xenopus embryos leads to duplication of the embryonic axis. Cell,1989.58(6):p.1075-84.
    150. Behrens, J., et al., Functional interaction of beta-catenin with the transcription factor LEF-1. Nature,1996.382(6592):p.638-42.
    151. Molenaar, M., et al., XTcf-3 transcription factor mediates beta-catenin-induced axis formation in Xenopus embryos. Cell,1996.86(3):p.391-9.
    152. Bhanot, P., et al., A new member of the frizzled family from Drosophila Junctions as a Wingless receptor. Nature,1996.382(6588):p.225-30.
    153. Wehrli, M., et al., arrow encodes an LDL-receptor-related protein essential for Wingless signalling. Nature,2000.407(6803):p.527-30.
    154. Kinzler, K.W., et al., Identification of FAP locus genes from chromosome 5q21. Science,1991. 253(5020):p.661-5.
    155. Su, L.K., B. Vogelstein, and K.W. Kinzler, Association of the APC tumor suppressor protein with catenins. Science,1993.262(5140):p.1734-7.
    156. Rubinfeld, B., et al., Association of the APC gene product with beta-catenin. Science,1993. 262(5140):p.1731-4.
    157. Kusserow, A., et al., Unexpected complexity of the Wnt gene family in a sea anemone. Nature, 2005.433(7022):p.156-60.
    158. Petersen, C.P. and P.W. Reddien, Wnt signaling and the polarity of the primary body axis. Cell, 2009.139(6):p.1056-68.
    159. Tanaka, K., Y. Kitagawa, and T. Kadowaki, Drosophila segment polarity gene product porcupine stimulates the posttranslational N-glycosylation of wingless in the endoplasmic reticulum. J Biol Chem,2002.277(15):p.12816-23.
    160. Willert, K., et al., Wnt proteins are lipid-modified and can act as stem cell growth factors. Nature,2003.423(6938):p.448-52.
    161. Takada, R., et al., Monounsaturated fatty acid modification of Wnt protein:its role in Wnt secretion. Dev Cell,2006.11(6):p.791-801.
    162. Franch-Marro, X., et al., In vivo role of lipid adducts on Wingless. J Cell Sci,2008.121(Pt 10): p.1587-92.
    163. Kurayoshi, M., et al., Post-translational palmitoylation and glycosylation of Wnt-5a are necessary for its signalling. Biochem J,2007.402(3):p.515-23.
    164. Janda, C.Y., et al., Structural basis of Wnt recognition by Frizzled. Science,2012.337(6090): p.59-64.
    165. Hofmann, K., A superfamily of membrane-bound O-acyltransferases with implications for wnt signaling. Trends Biochem Sci,2000.25(3):p.111-2.
    166. Kadowaki, T., et al., The segment polarity gene porcupine encodes a putative multitransmembrane protein involved in Wingless processing. Genes Dev,1996.10(24):p. 3116-28.
    167. Grzeschik, K.H., et al., Deficiency of PORCN, a regulator of Wnt signaling, is associated with focal dermal hypoplasia. Nat Genet,2007.39(7):p.833-5.
    168. Wang, X., et al., Mutations in X-linked PORCN, a putative regulator of Wnt signaling, cause focal dermal hypoplasia. Nat Genet,2007.39(7):p.836-8.
    169. Barrott, J.J., et al., Deletion of mouse Porcn blocks Wnt ligand secretion and reveals an ectodermal etiology of human focal dermal hypoplasia/Goltz syndrome. Proc Natl Acad Sci U S A,2011.108(31):p.12752-7.
    170. Biechele, S., B.J. Cox, and J. Rossant, Porcupine homolog is required for canonical Wnt signaling and gastrulation in mouse embryos. Dev Biol,2011.355(2):p.275-85.
    171. Banziger, C., et al., Wntless, a conserved membrane protein dedicated to the secretion of Wnt proteins from signaling cells. Cell,2006.125(3):p.509-22.
    172. Bartscherer, K., et al., Secretion of Wnt ligands requires Evi, a conserved transmembrane protein. Cell,2006.125(3):p.523-33.
    173. Goodman, R.M., et al., Sprinter:a novel transmembrane protein required for Wg secretion and signaling. Development,2006.133(24):p.4901-11.
    174. Port, F., et al., Wingless secretion promotes and requires retromer-dependent cycling of Wntless. Nat Cell Biol,2008.10(2):p.178-85.
    175. Korkut, C., et al., Trans-synoptic transmission of vesicular Wnt signals through Evi/Wntless. Cell,2009.139(2):p.393-404.
    176. Coudreuse, D.Y., et al., Wnt gradient formation requires retromer function in Wnt-producing cells. Science,2006.312(5775):p.921-4.
    177. Prasad, B.C. and S.G. Clark, Wnt signaling establishes anteroposterior neuronal polarity and requires retromer in C. elegans. Development,2006.133(9):p.1757-66.
    178. Belenkaya, T.Y., et al., The retromer complex influences Wnt secretion by recycling wntless from endosomes to the trans-Golgi network Dev Cell,2008.14(1):p.120-31.
    179. Franch-Marro, X., et al., Wingless secretion requires endosome-to-Golgi retrieval of Wntless/Evi/Sprinter by the retromer complex. Nat Cell Biol,2008.10(2):p.170-7.
    180. Yang, P.T., et al., Wnt signaling requires retromer-dependent recycling of MIG-14/Wntless in Wnt-producing cells. Dev Cell,2008.14(1):p.140-7.
    181. Panakova, D., et al., Lipoprotein particles are required for Hedgehog and Wingless signalling. Nature,2005.435(7038):p.58-65.
    182. Zecca, M., K. Basler, and G. Struhl, Direct and long-range action of a wingless morphogen gradient. Cell,1996.87(5):p.833-44.
    183. Mulligan, K.A., et al., Secreted Wingless-interacting molecule (Swim) promotes long-range signaling by maintaining Wingless solubility. Proc Natl Acad Sci U S A,2012.109(2):p. 370-7.
    184. van den Heuvel, M., et al., Distribution of the wingless gene product in Drosophila embryos:a protein involved in cell-cell communication. Cell,1989.59(4):p.739-49.
    185. Strand, M. and C.A. Micchelli, Quiescent gastric stem cells maintain the adult Drosophila stomach. Proc Natl Acad Sci U S A,2011.108(43):p.17696-701.
    186. Dann, C.E., et al., Insights into Wnt binding and signalling from the structures of two Frizzled cysteine-rich domains. Nature,2001.412(6842):p.86-90.
    187. Pinson, K.I., et al., An LDL-receptor-related protein mediates Wnt signalling in mice. Nature, 2000.407(6803):p.535-8.
    188. Tamai, K., et al., LDL-receptor-related proteins in Wnt signal transduction. Nature,2000. 407(6803):p.530-5.
    189. Gong, Y., et al., Wnt isoform-specific interactions with coreceptor specify inhibition or potentiation of signaling by LRP6 antibodies. PLoS One,2010.5(9):p. el 2682.
    190. Mao, J., et al., Low-density lipoprotein receptor-related protein-5 binds to Axin and regulates the canonical Wnt signaling pathway. Mol Cell,2001.7(4):p.801-9.
    191. He, X., et al., LDL receptor-related proteins 5 and 6 in Wnt/beta-catenin signaling:arrows point the way. Development,2004.131(8):p.1663-77.
    192. Tamai, K., et al., A mechanism for Wnt coreceptor activation. Mol Cell,2004.13(1):p. 149-56.
    193. Zeng, X., et al., A dual-kinase mechanism for Wnt co-receptor phosphorylation and activation. Nature,2005.438(7069):p.873-7.
    194. Davidson, G., et al., Casein kinase 1 gamma couples Wnt receptor activation to cytoplasmic signal transduction. Nature,2005.438(7069):p.867-72.
    195. Chen, W., et al., Dishevelled 2 recruits beta-arrestin 2 to mediate Wnt5A-slimulated endocytosis of Frizzled 4. Science,2003.301(5638):p.1391-4.
    196. Fiedler, M., et al., Dishevelled interacts with the DIX domain polymerization interface of Axin to interfere with its function in down-regulating beta-catenin. Proc Natl Acad Sci U S A,2011. 108(5):p.1937-42.
    197. Schwarz-Romond, T., et al., The DIX domain of Dishevelled confers Wnt signaling by dynamic polymerization. Nat Struct Mol Biol,2007.14(6):p.484-92.
    198. Schwarz-Romond, T., et al., The Wnt signalling effector Dishevelled forms dynamic protein assemblies rather than stable associations with cytoplasmic vesicles. J Cell Sci,2005.118(Pt 22):p.5269-77.
    199. Taelman, V.F., et al., Wnt signaling requires sequestration of glycogen synthase kinase 3 inside multivesicular endosomes. Cell,2010.143(7):p.1136-48.
    200. Bovolenta, P., et al., Beyond Wnt inhibition:new functions of secreted Frizzled-related proteins in development and disease. J Cell Sci,2008.121(Pt 6):p.737-46.
    201. Glinka, A., et al., Dickkopf-1 is a member of a new family of secreted proteins and functions in head induction. Nature,1998.391(6665):p.357-62.
    202. Ellwanger, K., et al., Targeted disruption of the Wnt regulator Kremen induces limb defects and high bone density. Mol Cell Biol,2008.28(15):p.4875-82.
    203. Semenov, M.V., X. Zhang, and X. He, DKKl antagonizes Wnt signaling without promotion of LRP6 internalization and degradation. J Biol Chem,2008.283(31):p.21427-32.
    204. Semenov, M., K. Tamai, and X. He, SOST is a ligand for LRP5/LRP6 and a Wnt signaling inhibitor. J Biol Chem,2005.280(29):p.26770-5.
    205. Shimomura, Y., et al., APCDD1 is a novel Wnt inhibitor mutated in hereditary hypotrichosis simplex. Nature,2010.464(7291):p.1043-7.
    206. Monroe, D.G., et al., Update on Wnt signaling in bone cell biology and bone disease. Gene, 2012.492(1):p.1-18.
    207. Gong, Y., et al., LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development. Cell,2001.107(4):p.513-23.
    208. Boyden, L.M., et al., High bone density due to a mutation in LDL-receptor-related protein 5. N Engl J Med,2002.346(20):p.1513-21.
    209. Little, R.D., et al., A mutation in the LDL receptor-related protein 5 gene results in the autosomal dominant high-bone-mass trait. Am J Hum Genet,2002.70(1):p.11-9.
    210. Ellies, D.L., et al., Bone density ligand, Sclerostin, directly interacts with LRP5 but not LRP5G171 V to modulate Wnt activity. J Bone Miner Res,2006.21(11):p.1738-49.
    211. Semenov, M.V. and X. He, LRP5 mutations linked to high bone mass diseases cause reduced LRP5 binding and inhibition by SOST. J Biol Chem,2006.281(50):p.38276-84.
    212. Ai, M., et al., Reduced affinity to and inhibition by DKKl form a common mechanism by which high bone mass-associated missense mutations in LRP5 affect canonical Wnt signaling. Mol Cell Biol,2005.25(12):p.4946-55.
    213. Balemans, W., et al., Increased bone density in sclerosteosis is due to the deficiency of a novel secreted protein (SOST). Hum Mol Genet,2001.10(5):p.537-43.
    214. Brunkow, M.E., et al., Bone dysplasia sclerosteosis results from loss of the SOST gene product, a novel cystine knot-containing protein. Am J Hum Genet,2001.68(3):p.577-89.
    215. Mani, A., et al., LRP6 mutation in a family with early coronary disease and metabolic risk factors. Science,2007.315(5816):p.1278-82.
    216. Jenkins, Z.A., et al., Germline mutations in WTX cause a sclerosing skeletal dysplasia but do not predispose to tumorigenesis. Nat Genet,2009.41(1):p.95-100.
    217. Wang, Y.K., et al., Characterization and expression pattern of the frizzled gene Fzd9, the mouse homolog of FZD9 which is deleted in Williams-Beuren syndrome. Genomics,1999. 57(2):p.235-48.
    218. Tian, E., et al., The role of the Wnt-signaling antagonist DKK1 in the development of osteolytic lesions in multiple myeloma. N Engl J Med,2003.349(26):p.2483-94.
    219. Robitaille, J., et al., Mutant frizzled-4 disrupts retinal angiogenesis in familial exudative vitreoretinopathy. Nat Genet,2002.32(2):p.326-30.
    220. Toomes, C., et al., Mutations in LRP5 or FZD4 underlie the common familial exudative vitreoretinopathy locus on chromosome 11q. Am J Hum Genet,2004.74(4):p.721-30.
    221. Richter, M., et al., Retinal vasculature changes in Norrie disease mice. Invest Ophthalmol Vis Sci,1998.39(12):p.2450-7.
    222. Wang, Y., et al., Progressive cerebellar, auditory, and esophageal dysfunction caused by targeted disruption of the frizzled-4 gene. J Neurosci,2001.21(13):p.4761-71.
    223. Kato, M., et al., Cbfal-independent decrease in osteoblast proliferation, osteopenia, and persistent embryonic eye vascularization in mice deficient in Lrp5, a Wnt coreceptor. J Cell Biol,2002.157(2):p.303-14.
    224. Xia, C.H., et al., A model for familial exudative vitreoretinopathy caused by LPR5 mutations. Hum Mol Genet,2008.17(11):p.1605-12.
    225. Xu, Q., et al., Vascular development in the retina and inner ear:control by Norrin and Frizzled-4, a high-affinity ligand-receptor pair. Cell,2004.116(6):p.883-95.
    226. Junge, H.J., et al., TSPAN12 regulates retinal vascular development by promoting Norrin-but not Wnt-induced FZD4/beta-catenin signaling. Cell,2009.139(2):p.299-311.
    227. Nikopoulos, K., et al., Next-generation sequencing of a 40 Mb linkage interval reveals TSPAN12 mutations in patients with familial exudative vitreoretinopathy. Am J Hum Genet, 2010.86(2):p.240-7.
    228. Poulter, J.A., et al., Mutations in TSPAN12 cause autosomal-dominant familial exudative vitreoretinopathy. Am J Hum Genet,2010.86(2):p.248-53.
    229. Parma, P., et al., R-spondinl is essential in sex determination, skin differentiation and malignancy. Nat Genet,2006.38(11):p.1304-9.
    230. Bell, S.M., et al., R-spondin 2 is required for normal laryngeal-tracheal, lung and limb morphogenesis. Development,2008.135(6):p.1049-58.
    231. Nam, J.S., et al., Mouse R-spondin2 is required for apical ectodermal ridge maintenance in the hindlimb. Dev Biol,2007.311(1):p.124-35.
    232. Yamada, W., et al., Craniofacial malformation in R-spondin2 knockout mice. Biochem Biophys Res Commun,2009.381(3):p.453-8.
    233. Barker, N., et al., Crypt stem cells as the cells-of-origin of intestinal cancer. Nature,2009. 457(7229):p.608-11.
    234. Jaks, V., et al., Lgr5 marks cycling, yet long-lived, hair follicle stem cells. Nat Genet,2008. 40(11):p.1291-9.
    235. Snippert, H.J., et al., Lgr6 marks stem cells in the hair follicle that generate all cell lineages of the skin. Science,2010.327(5971):p.1385-9.
    236. Rivera, M.N., et al., An X chromosome gene, WTX, is commonly inactivated in Wilms tumor. Science,2007.315(5812):p.642-5.
    237. Major, M.B., et al., Wilms tumor suppressor WTX negatively regulates WNT/beta-catenin signaling. Science,2007.316(5827):p.1043-6.
    238. Regimbald-Dumas, Y. and X. He, Wnt signalling:What The X@# is WTX? EMBO J,2011. 30(8):p.1415-7.
    239. Aberle, H., et al., beta-catenin is a target for the ubiquitin-proteasome pathway. EMBO J, 1997.16(13):p.3797-804.
    240. Li, V.S., et al., Wnt signaling through inhibition of beta-catenin degradation in an intact Axinl complex. Cell,2012.149(6):p.1245-56.
    241. Peifer, M., et al., wingless signal and Zeste-white 3 kinase trigger opposing changes in the intracellular distribution of Armadillo. Development,1994.120(2):p.369-80.
    242. Korswagen, H.C., M.A. Herman, and H.C. Clevers, Distinct beta-catenins mediate adhesion and signalling functions in C. elegans. Nature,2000.406(6795):p.527-32.
    243. van de Wetering, M., et al., Armadillo coactivates transcription driven by the product of the Drosophila segment polarity gene dTCF. Cell,1997.88(6):p.789-99.
    244. Cavallo, R.A., et al., Drosophila Tcf and Groucho interact to repress Wingless signalling activity. Nature,1998.395(6702):p.604-8.
    245. Roose, J., et al., The Xenopus Wnt effector XTcf-3 interacts with Groucho-related transcriptional repressors. Nature,1998.395(6702):p.608-12.
    246. Hikasa, H., et al., Regulation of TCF3 by Wnt-dependent phosphorylation during vertebrate axis specification. Dev Cell,2010.19(4):p.521-32.
    247. Lee, W., et al., Homeodomain-interacting protein kinases (Hipks) promote Wnt/Wg signaling through stabilization of beta-catenin/Arm and stimulation of target gene expression. Development,2009.136(2):p.241-51.
    248. Lustig, B., et al., Negative feedback loop of Wnt signaling through upregulation of conductin/axin2 in colorectal and liver tumors. Mol Cell Biol,2002.22(4):p.1184-93.
    249. Chang, M.V., et al., Activation of wingless targets requires bipartite recognition of DNA by TCF. Curr Biol,2008.18(23):p.1877-81.
    250. Kramps, T., et al., Wnt/wingless signaling requires BCL9/legless-mediated recruitment of pygopus to the nuclear beta-catenin-TCF complex. Cell,2002.109(1):p.47-60.
    251. Parker, D.S., J. Jemison, and K.M. Cadigan, Pygopus, a nuclear PHD-finger protein required for Wingless signaling in Drosophila. Development,2002.129(11):p.2565-76.
    252. Thompson, B., et al., A new nuclear component of the Wnt signalling pathway. Nat Cell Biol, 2002.4(5):p.367-73.
    253. Brack, A.S., et al., BCL9 is an essential component of canonical Wnt signaling that mediates the differentiation of myogenic progenitors during muscle regeneration. Dev Biol,2009. 335(1):p.93-105.
    254. Schwab, K.R., et al., Pygol and Pygo2 roles in Wnt signaling in mammalian kidney development. BMC Biol,2007.5:p.15.
    255. Stadeli, R., R. Hoffmans, and K. Basler, Transcription under the control of nuclear Arm/beta-catenin. Curr Biol,2006.16(10):p. R378-85.
    256. Mosimann, C., G. Hausmann, and K. Basler, Parafibromin/Hyrax activates Wnt/Wg target gene transcription by direct association with beta-catenin/Armadillo. Cell,2006.125(2):p. 327-41.
    257. Sugioka, K., K. Mizumoto, and H. Sawa, Wnt regulates spindle asymmetry to generate asymmetric nuclear beta-catenin in C. elegans. Cell,2011.146(6):p.942-54.
    258. Goentoro, L. and M.W. Kirschner, Evidence that fold-change, and not absolute level, of beta-catenin dictates Wnt signaling. Mol Cell,2009.36(5):p.872-84.
    259. Losick, V.P., et al., Drosophila stem cell niches:a decade of discovery suggests a unified view of stem cell regulation. Dev Cell,2011.21(1):p.159-71.
    260. DasGupta, R. and E. Fuchs, Multiple roles for activated LEF/TCF transcription complexes during hair follicle development and differentiation Development,1999.126(20):p.4557-68.
    261. Andl, T., et al., WNT signals are required for the initiation of hair follicle development. Dev Cell,2002.2(5):p.643-53.
    262. Reya, T., et al., A role for Wnt signalling in self-renewal of haematopoietic stem cells. Nature, 2003.423(6938):p.409-14.
    263. Gat, U., et al., De Novo hair follicle morphogenesis and hair tumors in mice expressing a truncated beta-catenin in skin. Cell,1998.95(5):p.605-14.
    264. ten Berge, D., et al., Embryonic stem cells require Wnt proteins to prevent differentiation to epiblast stem cells. Nat Cell Biol,2011.13(9):p.1070-5.
    265. van Amerongen, R., A.N. Bowman, and R. Nusse, Developmental stage and time dictate the fate of Wnt/beta-catenin-responsive stem cells in the mammary gland. Cell Stem Cell,2012. 11(3):p.387-400.
    266. Barker, N. and H. Clevers, Leucine-rich repeat-containing G-protein-coupled receptors as markers of adult stem cells. Gastroenterology,2010.138(5):p.1681-96.
    267. Zeng, Y.A. and R. Nusse, Wnt proteins are self-renewal factors for mammary stem cells and promote their long-term expansion in culture. Cell Stem Cell,2010.6(6):p.568-77.
    268. Kinzler, K.W. and B. Vogelstein, Lessons from hereditary colorectal cancer. Cell,1996.87(2): p.159-70.
    269. Liu, W., et al., Mutations in AXIN2 cause colorectal cancer with defective mismatch repair by activating beta-catenin/TCFsignalling. Nat Genet,2000.26(2):p.146-7.
    270. Lammi, L., et al., Mutations in AXIN2 cause familial tooth agenesis and predispose to colorectal cancer. Am J Hum Genet,2004.74(5):p.1043-50.
    271. Wood, L.D., et al., The genomic landscapes of human breast and colorectal cancers. Science, 2007.318(5853):p.1108-13.
    272. Bass, A.J., et al., Genomic sequencing of colorectal adenocarcinomas identifies a recurrent VTI1A-TCF7L2 fusion. Nat Genet,2011.43(10):p.964-8.
    273. Rubinfeld, B., et al., Stabilization of beta-catenin by genetic defects in melanoma cell lines. Science,1997.275(5307):p.1790-2.
    274. Vermeulen, L., et al., Wnt activity defines colon cancer stem cells and is regulated by the microenvironment. Nat Cell Biol,2010.12(5):p.468-76.
    275. Merlos-Suarez, A., et al., The intestinal stem cell signature identifies colorectal cancer stem cells and predicts disease relapse. Cell Stem Cell,2011.8(5):p.511-24.
    276. Kanazawa, A., et al., Association of the gene encoding wingless-type mammary tumor virus integration-site family member 5B (WNT5B) with type 2 diabetes. Am J Hum Genet,2004. 75(5):p.832-43.
    277. Christodoulides, C., et al., WNT10B mutations in human obesity. Diabetologia,2006.49(4):p. 678-84.
    278. Grant, S.F., et al., Variant of transcription factor 7-like 2 (TCF7L2) gene confers risk of type 2 diabetes. Nat Genet,2006.38(3):p.320-3.
    279. Tong, Y., et al., Association between TCF7L2 gene polymorphisms and susceptibility to type 2 diabetes mellitus:a large Human Genome Epidemiology (HuGE) review and meta-analysis. BMC Med Genet,2009.10:p.15.
    280. Savic, D., et al., Alterations in TCF7L2 expression define its role as a key regulator of glucose metabolism. Genome Res,2011.21(9):p.1417-25.
    281. Huber, A.H., W.J. Nelson, and W.I. Weis, Three-dimensional structure of the armadillo repeat region of beta-catenin. Cell,1997.90(5):p.871-82.
    282. Lepourcelet, M., et al., Small-molecule antagonists of the oncogenic Tcf/beta-catenin protein complex. Cancer Cell,2004.5(1):p.91-102.
    283. Lu, J., et al., Structure-activity relationship studies of small-molecule inhibitors of Wnt response. Bioorg Med Chem Lett,2009.19(14):p.3825-7.
    284. Huang, S.M., et al., Tankyrase inhibition stabilizes axin and antagonizes Wnt signalling. Nature,2009.461(7264):p.614-20.
    285. Thome, C.A., et al., Small-molecule inhibition of Wnt signaling through activation of casein kinase lalpha. Nat C em Biol,2010.6(11):p.829-36.
    286. Malanchi, I. and J. Huelsken, Cancer stem cells:never Wnt away from the niche. Curr Opin Oncol,2009.21(1):p.41-6.
    287. Nguyen, D.X., et al., WNT/TCF signaling through LEFI and HOXB9 mediates lung adenocarcinoma metastasis. Cell,2009.138(1):p.51-62.

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