LIQUID HYBRIDIZATION ANALYSIS OF TSH RECEPTOR MESSENGER-RNA IN NORMALAND ABNORMAL HUMAN THYROID TISSUES

Radiolabeled human TSH receptor (hTSHR) cRNA probes encoding nucleotid es 37-2298 and 37-209, with unlabeled sense RNA control segments, were used in a liquid hybridization assay and found to be highly specific and sensitive enabling detection of 0.5 fmol of hTSHR mRNA. Using norm al human thyroid monolayer cell cultures we calculated that the averag e number of TSHR mRNA transcripts was 95 +/- 5 per cell under in vitro basal conditions. We found no significant difference between the hTSH R mRNA concentrations of intact normal human thyroid tissue (n = 4) an d specimens from patients with multinodular goiter (n = 5) and Graves' disease thyroid tissues (n = 5) (23.0, 25.2, and 27.6 fmol of hTSHR m RNA/mg total cellular RNA, respectively). However, there was a relativ e deficiency of hTSHR mRNA in some samples of thyroid papillary carcin oma tissue (n = 5) (12 fmol of hTSHR mRNA/mg total RNA, p < 0.05). The hTSHR 37-2298 probe was fully protected in normal and abnormal thyroi d tissues, consistent with the absence of large deletions or insertion s in the hTSHR mRNA transcripts but additional bands were present, con sistent with the production of splicing variants.