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 2
Localization of cathepsins K and L. 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 K (a–c) or cathepsin L (d–f). Compared with the WT (a, inset, arrows), cathepsin K–positive vesicles were smaller in cathepsin B^–/– (b, top inset, arrows) and larger in cathepsin L^–/– thyroid epithelial cells (c, inset, arrows). Cathepsin K was absent from thyroid follicle lumina of cathepsin B^–/– mice but was detectable within lumina of WT or cathepsin L^–/– thyroids (asterisks). Immunolabeling of cathepsin K was also observed at the apical plasma membrane of cathepsin B^–/– thyroid epithelial cells (b, bottom inset, arrowheads). In addition, cathepsin K–positive inclusions were frequently detected within the luminal content of cathepsin L^–/– mice (c, open circles). In WT mice, cathepsin L was detected mainly within endocytic vesicles (d, arrows) and, in a few follicles, in association with the apical plasma membrane of thyroid epithelial cells (d and inset in d, arrowheads). Deficiencies in cathepsin B and/or cathepsin K demonstrated a lack of cathepsin L at the apical plasma membrane and resulted in an enhancement of immunolabeling of thyroid follicle lumina (e and f, asterisks). The redistribution of cathepsin L was less obvious than that of cathepsin B (compare with Figure 1). Bars: 50 μm; in insets: 20 μm.