Transcriptional activity of a mutant thyroid hormone receptor beta in a family with generalized resistance to thyroid hormone.
We previously reported a family with generalized resistance to thyroid hormone (GRTH) which had a point mutation with codon 448 CCT (proline) being converted to ACT (threonine) in the thyroid hormone receptor (TR) beta. To characterize functional properties of the mutant TR beta, transient expression studies were performed in COS cells. A double stranded oligonucleotide encompassing thyroid hormone response element (TRE) derived from the rat GH gene was synthesized. We constructed chloramphenicol acetyl transferase (CAT) plasmid containing the thymidine kinase promoter under the control of the rat GH TRE. T3 induction of CAT activity by the mutant TR beta was significantly reduced as compared with that of the normal TR beta. This was observed in the presence of 0.5-50 nM T3, but not at 500 nM T3. When the normal and mutant TR beta were cotransfected, the mutant TR beta inhibited gene activation regulated by the normal TR beta. However, a high molar excess was necessary to significantly inhibit the function of the normal receptor. Additionally, the binding of in vitro synthesized mutant TR beta to TRE was preserved.
Shuto
Y
Y
Department of Medicine, Nippon Medical School, Tokyo, Japan.
Okazaki
T
T
Wakabayashi
I
I
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003062:Codon; D004247:DNA / Q000235:genetics / Q000378:metabolism; D005813:Genes, Synthetic; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D011988:Receptors, Thyroid Hormone / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D013937:Thymidine Kinase / Q000235:genetics; D013963:Thyroid Hormones / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D003062:Codon; D011988:Receptors, Thyroid Hormone; D011993:Recombinant Fusion Proteins; D013963:Thyroid Hormones; D004247:DNA; D013937:Thymidine Kinase