Article Figures & Data
Figures
- Fig. 1.
Disruption of the Lkb1 gene in mouse ES cells. A, schematic representation of the targeting strategy by homologous recombination. The top part illustrates the wild-type Lkb1 allele, whereas the middle and bottom parts show the targeting vector and the targeted Lkb1 allele, respectively. Solid boxes, exons; Neo, neomycin resistance gene cassette; DT-A, diphtheria toxin gene cassette; ∗, initiation codons; flags, termination codons; arrowheads, PCR primer positions; hatched box, probe used for Southern analysis; Bg, BglII; H, HindIII; B, BamHI. B, genotyping of the intercross offspring by Southern analysis. The 7-kb fragment corresponds to the wild-type allele, whereas the 11-kb fragment corresponds to the targeted allele. C, RT-PCR analysis of the wild-type and Lkb1 (+/−) mouse gastric mucosa, amplified for exons 1 to 6 (left) and exons 1 to 8 (right). Bands for the alternatively spliced (arrowheads), as well as full length (arrows) Lkb1 cDNA were detected in the Lkb1 (+/−) mouse gastric mucosa.
- Fig. 2.
Incidence of gastrointestinal polyps in the Lkb1 (+/−) mice. Each circle represents a necropsied individual. Most mice >20 weeks of age developed gastric polyps (•), whereas the incidence of small intestinal polyps was lower (○).
- Fig. 3.
Morphological and immunohistochemical examinations of gastrointestinal polyps. A and B, dissection micrographs of gastric polyps (A) and a small intestinal polyp (B). C–F, H&E staining (C and E) and immunostaining (D and F) of the gastric polyps. The large gastric polyp is pedunculated (C) and consists of different types of epithelial cells (E, inset). A bromodeoxyuridine (BrdU) incorporation assay shows frequent proliferation of the tumor epithelial cells (D). Immunostaining with an anti-αSMA antibody shows an arborizing network of smooth muscle bundles in the hamartoma (F). G, histology of a small intestinal polyp shows a similar morphology to that in the gastric polyps, H&E. H and I, β-catenin localizes in the basolateral membrane of a gastric polyp (H) and a small intestinal polyp (I). Bars: A, 5 mm; B and C, 2 mm; D and E, 200 μm; F and G, 500 μm; H and I, 100 μm.
- Fig. 4.
Lkb1 expression in hamartomas. A, a genomic PCR analysis shows that both targeted (KO) and wild-type (WT) Lkb1 alleles are retained in the gastric hamartomas (P), as well as in the normal mucosa (N). B, a Western immunoblot analysis of the normal (N) and polyp (P) tissues. C, a histogram of quantified band intensities of (B). Compared with the wild-type mucosa, almost the half level of LKB1 is expressed in either the normal or polyp tissues of the Lkb1 (+/−) mice. Bars, SD. D–G, in situ analysis of the Lkb1 mRNA using an antisense probe (D and F) and a sense probe (E and G). Lkb1 is expressed in the normal mucosa (D) and hamartoma epithelial cells (F). Bars: D and E, 200 μm; F and G, 500 μm.
Volume 62, Issue 8
