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. Author manuscript; available in PMC: 2012 Sep 1.
Published in final edited form as: Gastroenterology. 2011 May 18;141(3):1003–1013.e10. doi: 10.1053/j.gastro.2011.05.007

Figure 5.

Figure 5

Kras/KRAS activation does not increase presumptive colon stem cells. (A and B) RNA was extracted from proximal colon epithelium of four G22Cre Apcfl/fl, seven G22Cre KrasLSL-G12D, and seven control mice. Expression of Olfm4, Lgr5 and Msi1, relative to U6, was measured by qRT-PCR. (C) IHC staining for Msi1 in proximal colon of wild type, G22Cre KrasLSL-G12D, and G22Cre Apcfl/fl mice. Arrows indicate Msi1-expressing cells near the crypt base. Scale bars, 50 μm. (D) GFP imaging in proximal colon tissues counter-stained with Hoechst 33342. Lgr5-EGFP-IRES-CreERT2 KrasLSL-G12D mice and Lgr5-EGFP-IRES-CreERT2 control mice were analyzed after tamoxifen treatment to activate Cre. The circled region denotes Lgr5 expression restricted to the crypt base. Scale bars, 50 μm. (E) LGR5 and MSI1 expression in human HPPs, adenomas, and normal colon mucosa. (upper panels) In situ hybridization was performed with digoxigenin-labeled LGR5 antisense or control LGR5 sense riboprobes. Arrows indicate LGR5-expressing cells at the crypt base. Scale bars, 50 μm for normal mucosa and HPPs, and 100 μm for adenomas. (lower panels) IHC analysis of MSI1 expression. Scale bars, 50 μm. (F) Colony formation assay with IEC-6 cells expressing S33Y (serine 33 substitution with tyrosine) mutant β-catenin, KRAS G12V, or control vector. *P < .01.

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