Dominant negative effect of mutated thyroid stimulating hormone receptor (P556L) causes hypothyroidism in C.RF-Tshr(hyt/wild) mice.
C.RF-Tshr(hyt/hyt) mice have a mutated thyroid stimulating hormone receptor (P556L-TSHR) and these mice develop severe hypothyroidism. We found that C.RF-Tshr(hyt/wild) heterozygous mice are also in a hypothyroid state. Thyroid glands from C.RF-Tshr(hyt/wild) mice are smaller than those from wild-type mice, and (125)I uptake activities of the former are significantly lower than those in the latter. When TSHR (TSHR(W)) and P556L-TSHR (TSHR(M)) cDNAs were cloned and co-transfected into HEK 293 cells, the cells retained (125)I-TSH binding activity, but cAMP response to TSH was decreased to about 20% of HEK 293 cells transfected with TSHR(W) cDNA. When TSHR(W) and TSHR(M) were tagged with eCFP or eYFP, we observed fluorescence resonance energy transfer (FRET) in HEK 293 cells expressing TSHR(W)-eCFP and TSHR(W)-eYFP in the absence of TSH, but not in the presence of TSH. In contrast, we obtained FRET in HEK 293 cells expressing TSHR(W)-eCFP and TSHR (M)-eYFP, regardless of the presence or absence of TSH. These results suggest that P556L TSHR has a dominant negative effect on TSHR(W) by impairing polymer to monomer dissociation, which decreases TSH responsiveness and induces hypothyroidism in C.RF-Tshr(hyt/wild) mice.
The Third Department of Internal Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo City, Yamanashi, Japan. endot@yamanashi.ac.jp
Toyoshi
T
Endo
Tetsuro
T
Kobayashi
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D000242:Cyclic AMP / Q000378:metabolism; D017931:DNA Primers; D018076:DNA, Complementary; D031541:Fluorescence Resonance Energy Transfer; D057809:HEK293 Cells; D006801:Humans; D007037:Hypothyroidism / Q000235:genetics*; D051379:Mice; D009154:Mutation; D016133:Polymerase Chain Reaction; D011989:Receptors, Thyrotropin / Q000235:genetics*; D013972:Thyrotropin / Q000378:metabolism
D017931:DNA Primers; D018076:DNA, Complementary; D011989:Receptors, Thyrotropin; D013972:Thyrotropin; D000242:Cyclic AMP