Identification and functional analysis of novel inactivating thyrotropin receptor mutations in patients with thyrotropin resistance
Identification and functional analysis of novel inactivating thyrotropin receptor mutations in patients with thyrotropin resistance
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DOI：
10.1089/thy.2006.16.471
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发表时间：
2006-05-01
期刊：
影响因子：
6.6
通讯作者：
Murakami, Masami
中科院分区：
文献类型：
--
作者：
Tsunekawa, Katsuhiko;Onigata, Kazumichi;Murakami, Masami
目的：我们确定并分析了三个日本家族中促甲状腺激素（TSH）受体的新突变。设计：对TSH受体基因进行测序，确定突变位点。将突变型TSH受体转染COS-7细胞，分析其功能。患者：患者为R450 H突变和TSH受体基因新突变的复合杂合子。第1例患者为R450 H和V473 I的复合杂合子。第二个兄弟姐妹拥有R450 H和R519 C。第三个兄弟姐妹有R450 H和R519 G。结果如下：R450 H突变体表现出中度受损的受体功能和中度降低的细胞表面表达与以前的结果一致。V473 I突变体表现出几乎正常的TSH结合，环磷酸腺苷（cAMP）反应略有下降，肌醇磷酸（IP）反应中度下降，和几乎正常的细胞表面表达。在R519 C和R519 G突变体中，cAMP和IP的TSH结合和TSH刺激显著降低。细胞表面表达在R519 C突变体中降低，在R519 G突变体中可忽略不计。所有这些突变体都显示正常的细胞内合成TSH受体。结论：这些新的失活突变有助于理解TSH受体的结构-功能关系。迄今为止，在日本发现的所有TSH受体突变导致的TSH抵抗患者至少在一个等位基因中具有R450 H突变。这些观察结果表明，R450 H突变是日本TSH抵抗患者中常见的TSH受体突变。
Objective: We identified and analyzed novel thyrotropin (TSH) receptor mutations in three Japanese families with resistance to TSH. Design: The TSH receptor gene was sequenced and the mutations were determined. The mutant TSH receptors were transfected into COS-7 cells, and their functions were analyzed. Patients: The patients were compound-heterozygotes for the R450H mutation and novel mutations in the TSH receptor gene. The first patient was a compound-heterozygote for R450H and V473I. The second sibling possessed R450H and R519C. The third sibling had R450H and R519G. Results: The R450H mutant exhibited moderately impaired receptor functions and a moderately decreased cell surface expression in agreement with previous results. The V473I mutant exhibited an almost normal TSH binding, a slightly decreased cyclic adenosine monophosphate (cAMP) response, a moderately decreased inositolphosphate (IP) response, and an almost normal cell surface expression. TSH binding and TSH stimulation of cAMP and IPs were markedly decreased in the R519C and R519G mutants. Cell surface expression was decreased in the R519C mutant and negligible in the R519G mutant. All of these mutants showed normal intracellular synthesis of TSH receptors. Conclusions: These novel inactivating mutations contribute to understanding of the structure-function relationship of the TSH receptor. To date, all of the patients with TSH resistance resulting from TSH receptor mutations identified in Japan possessed the R450H mutation at least in one allele. These observations suggest that the R450H mutation is a commonly observed TSH receptor mutation in patients with TSH resistance in Japan.