Thyroid functions of mouse cathepsins B, K, and L
J. Clin. Invest. Bianca Friedrichs, et al. 111:1733 doi:10.1172/JCI15990 [Go to this article.]

Figure 3
Swelling of cathepsin D–containing lysosomes in thyroids of cathepsin B^–/–, L^–/–, or K^–/–/L^–/– mice. Confocal fluorescence micrographs of cryosections of thyroid glands from WT mice (+/+) or cathepsin-deficient mice of the indicated genotypes were immunolabeled with antibodies against cathepsin D (a and c–e). Diameters of cathepsin D–containing lysosomes were determined morphometrically and are given as means ± SE (b). In WT thyroid epithelial cells, cathepsin D–positive vesicles were distributed throughout the cells (a). An immunolabeling indicative of cathepsin D at the apical cell surface or over the follicle lumina was not observed in either genotype. The sizes of lysosomes of cathepsin K^–/– or B^–/–/K^–/– thyrocytes were similar to those of WT controls (b), whereas those from cathepsin B^–/–, L^–/–, or K^–/–/L^–/– thyroid epithelial cells were significantly enlarged (c–e). Cathepsin D was absent from the inner portions of enlarged lysosomes of thyroid epithelial cells with a deficiency in cathepsin L (d, arrows). Similarly, cathepsin B (Cath B) immunostainings revealed ringlike lysosomes in L^–/– thyrocytes (d, inset, arrows), indicating a tight association of cathepsins B and D with vesicular membranes in cathepsin L–deficient thyrocytes. N, nuclei. *P < 0.05, **P < 0.01. In b, n = 16, 12, 16, 19, 18, and 14, respectively, for sections of the different genotypes indicated. Bars: 20 μm.