Distribution of TRPC1, TRPC3, and TRPC6 in the human thyroid

Little is known about the protein expression of the transient receptor potential canonical (TRPC) channels 1, 3, and 6 in the thyroid. Research in human tissue is insufficient. Our aim was to investigate the distribution of TRPC1, 3, and 6 in the healthy human thyroid.

Healthy samples were collected from seven nitrite pickling salt-ethanol-polyethylene glycol-fixed cadavers and from one patient who had undergone neck surgery (5 males, 3 females; median = 81.0, interquartile range = 6.5 years). The protein expression profiles of TRPC1, 3, and 6 were assessed using immunohistochemistry with knockout-validated antibodies. A monoclonal calcitonin antibody was used to detect calcitonin-producing C-cells.

All samples were labeled as healthy, displaying age-appropriate signs of degeneration. TRPC1, 3, and 6 immunolabeling in thyrocytes showed irregular staining patterns leaving selected cells with intense staining, some without. The comparison of calcitonin- and TRPC1-, 3-, and 6-immunolabeled slides strongly suggested TRPC1, 3, and 6 expression in C-cells. Connective tissue showed no immunoreactivity.

This is, to the authors' knowledge, the first detailed description of the distribution of these channels in the human thyroid. We conclude that TRPC1, 3, and 6 are expressed in thyrocytes and C-cells of the human thyroid. Further studies are necessary to confirm these small-case-number results and to explore the relevance of these versatile channels in thyroidal health and disease.