Deletion of the RNaseIII Enzyme Dicer in Thyroid Follicular Cells Causes Hypothyroidism with Signs of Neoplastic Alterations
Figure 4
Conditional invalidation of Dicer late during thyroid development uncovers surprisingly severe hypothyroidism.
A: As for Pax8(Cre/+); Dicerflox/flox (−/−) mice, a PCR was performed in genomic DNA issued from thyroid from 4 weeks old mice. The different genotypes correspond to: wt (+/+) Dicerflox/flox, Tg(Cre/+); Dicerflox/flox (−/−) and Tg(Cre/+); Dicerflox/+ (+/−). Dicer excision upon cre recombination resulted in an absence of visible fragment that was observed in homozygous mice, whereas there was a single 1,300 bp fragment in the wt and the heterozygous mice. B: Total blood T4 was lower in Tg(Cre/+); Dicerflox/flox 3 weeks old mice (***, p<0.001; **, p<0.01, unpaired t test). Hematoxylin staining on paraffin sections on 3 weeks old Dicerflox/flox (+/+) (C) and Tg(Cre/+); Dicerflox/flox (−/−) (D, E) mice showed two different phenotypes for the −/− animals. In half of the Dicer KO litters, the follicular structure was moderately altered, but still present (D), and in the other half the follicular structure was lost (E).