Figure 1. Lineage tracing in the small intestine and colon confirms Lrig1 marks SCs.
(A-C) Generation of Lrig1-CreERT2/+ mice. (A) Schematic representation of the Lrig1-CreERT2 targeting vector. A tamoxifen-inducible Cre (CreERT2) was targeted into the translational initiation site of the endogenous Lrig1 locus. Southern blot analysis of embryonic SCs with 3′, 5′ and internal neo probes confirmed the correct integration at a frequency of 8.7% (B and data not shown). Chimeras were mated with FlpE mice to achieve germ-line transmission and neo cassette removal. The resulting heterozygous and homozygous mice were viable and fertile. (C) Lrig1-CreERT2 animals were genotyped by specific Lrig1-CreERT2 PCR. (D0-G0) Low-power view of Lrig1-CreERT2/+;R26RLacZ/+ lineage-labeled small intestine at different time points following a single i.p. injection of 2mg tamoxifen. (D1-G1) Representative sections of high-power view of β-gal+ small intestine. (H0-K0) Low-power view of Lrig1-CreERT2/+;R26RLacZ/+ lineage-labeled colon at different time points following a single i.p. injection of 2mg tamoxifen. (H1-K1) Representative sections of high-power view of β-gal+ colonic crypts. Scale bars represent 100μm in D0 and H0; 200μm in E0-G0 and I0-K0; 50μm in D1-G1 and 25μm in H1-K1. See also Figure S1 and Table S1-S2.