Numerous renal abnormalities accompany thyroid disease, most of which have
been ascribed to the effects of thyroid hormone on renal metabolism. In the
present report, we investigate the renal expression of the nominally thyro
id-specific proteins, thyroid-stimulating hormone (TSH) receptor (TSHR) and
thyroglobulin (Tg), as potential links between renal and thyroid function.
The expression of TSHR has been identified in several extrathyroidal tissu
es, but its presence in the kidney remains controversial. We have used reve
rse-transcriptase polymerase chain reaction and DNA sequencing to demonstra
te the presence of TSHR transcript in human and mouse kidney, in a primary
culture of human kidney, and in a green monkey kidney epithelioid cell line
. Furthermore, human kidney cells responded to TSH with a 2.5-fold increase
in intracellular cyclic adenosine monophosphate, suggesting the presence o
f functional TSHR protein. Comparison of renal expression of TSHR in a bovi
ne growth hormone transgenic mouse model of progressive glomerulosclerosis
with control mice suggested increased TSHR transcript in the renal cortex o
f transgenic animals. TSHR transcript was also detected in mouse mesangial
cells in vitro which responded to TSH with significant increases in the for
mation of three-dimensional hillhocks. Polymerase chain reaction also confi
rmed the presence of Tg transcript in human and mouse kidneys and in mouse
mesangial cells, but no effect of either TSH or cyclic adenosine monophosph
ate on Tg transcript levels could be discerned. Immunofluorescent staining
with a monoclonal anti-Tg antibody identified positive staining in the cyto
plasm of mesangial cells. These data suggest that the kidney is capable of
expressing the thyroid-specific genes, TSHR and Tg, which could conceivably
mediate effects of thyroid disease in the kidney. Copyright (C) 2000 S. Ka
rger AG, Basel.