Functional analysis of the angio-follicular unit of the mouse thyroid gland

The need for diagnostic tools in thyroid research is evident since experimental guidelines for thyroid function analysis are constantly evolving. Therefore, we developed a non-biased, all-in-one diagnostic tool for the analysis of the mouse thyroid gland focussing on epithelial and endothelial functional parameters in a standardized and reproducible manner. High quality images of immuno-labelled cryo-sections were investigated by morphometry through a script for automated analysis based on the CellProfiler™-platform. The intra-thyroidal micro-vasculature was analysed by lectin labelling, while thyroid epithelial cell proliferation, thyroglobulin utilization, and thyroid hormone transporters were assessed by indirect immuno-fluorescence and immuno-blotting. The thyroid glands of animals deficient in the thyroglobulin processing enzyme cathepsin K and/or the thyroid hormone transporters Mct8 and Mct10 showed alterations in thyroid follicle sizes, epithelial extensions and proliferation rates, which differed significantly from those of wild type littermates. Thyroids of cathepsin K-deficient mice showed increased Mct8 protein levels and thyrocyte proliferation rates were altered. Thyroids from mice deficient in Mct8 or Mct10 were characterized by increased endothelial density and altered states of thyroglobulin cross-linking and degradation capabilities. We conclude that the investigation of thyroid epithelial and endothelial cells making up the angio-follicular unit is better approachable by our refinement of the semi-quantitative cell biological tool box described in this study.

Supported by the Deutsche Forschungsgemeinschaft, SPP 1629, Thyroid Trans Act, BR 1308/11 – 1.