(A) Adult β-Catenin ex3fl/fl; R26R-tdT;
Lyz1CreER mice were injected by tamoxifen and
assessed for proliferation after 8 and 24 hours. Animals were labeled with EdU
for 30 minutes before sacrifice.
(B) 8 and 24 hours after tamoxifen injection,
tdT+ Paneth cells (purple) were readily detected with
nuclear β-Catenin signals (green, pointed by arrowheads).
β-Catenin remained largely at junctions in tdT−
cells.
(C) 8 and 24 hours after tamoxifen injection to induce
β-Catenin activation, tdT+ Paneth cells (red) did not
show EdU incorporation (green). E-Cad (in white) was used to outline cell
boundaries.
(D) Genomic PCR using two sets of PCR primers (F+R1;
F+R2) revealed robust recombination (excision of exon 3) in FACS-sorted
tdT+ cells from tamoxifen-injected
ex3fl/fl; R26R-tdT; Lyz1CreER and
ex3fl/+; R26R-tdT;
Lyz1CreER mice. Water and tail DNA served as
controls.
(E) Adult β-Catenin ex3fl/fl; R26R-tdT;
Lyz1CreER mice was subcutaneously embedded with
21-day slow-releasing tamoxifen pellets, and assessed after a prolonged tracing
up to 1, 3, and 6 months.
(F) Tamoxifen-treated β-Catenin ex3fl/fl;
R26R-tdT; Lyz1CreER mice, after a long-term tracing did
not show epithelial hyperplasia or adenoma formation at 3 and 6 months (total of
8 mice).
(G) Tamoxifen-treated β-Catenin ex3fl/fl;
Villin-CreER mice exhibited formation of tubular adenoma within 1
week. (H-I), Lysozyme-expressing Paneth cells of above
tamoxifen-treated animals did not express cell proliferation marker Ki67 (G, I)
and PCNA (H, J).
Scale bars, 10 μm.