Loss-of-Function Variants in a Hungarian Cohort Reveal Structural Insights on TSH Receptor Maturation and Signaling
Loss-of-Function Variants in a Hungarian Cohort Reveal Structural Insights on TSH Receptor Maturation and Signaling
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DOI：
10.1210/jc.2014-4511
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发表时间：
2015-07-01
影响因子：
5.8
通讯作者：
Persani, Luca
中科院分区：
文献类型：
--
作者：
Labadi, Arpad;Grassi, Elisa Stellaria;Persani, Luca
背景：先天性甲状腺功能减退症（CH）是最常见的先天性内分泌疾病之一，具有遗传背景。尽管在匈牙利建立了完善的新生儿CH筛查计划，但尚未对潜在的遗传改变进行系统的检查。目的：我们的目的是探讨匈牙利CH患者队列中的TSH受体（TSHR）突变。患者：选择了85例无亲缘关系的永久性原发CH患者，均在新生儿筛查时确诊。TSHR基因的编码外显子进行测序，并与甲状腺特异性临床参数一起进行评价。新突变的功能特点进行了实验研究，并建立了比较分子models.Results：在4例患者（1杂合子和3复合杂合子），7 TSHR突变被确定。其中，N432（1.50）D和P449（2.39）L是新的错义突变。重要的是，N432（1.50）残基在G蛋白偶联受体中高度保守，其功能尚未在人糖蛋白激素受体中研究。我们的研究结果表明，N432（1.50）D突变破坏了重要的，结构稳定的分子内相互作用，并最终导致受体的完全细胞内保留。另一方面，P449（2.39）位于受体的细胞内部分，这在G蛋白偶联中是重要的。结论：TSHR基因突变在匈牙利CH患者中普遍存在，新的基因突变揭示了N432（1.50）和P449（2.39）残基分别在受体表达和信号转导中的重要结构作用。
Context: Congenital hypothyroidism (CH) is one of the most common inborn endocrine disorders with genetic background. Despite the well-established newborn CH screening program in Hungary, no systematic examination of the underlying genetic alterations has been performed as yet.Objective: We aimed to explore TSH receptor (TSHR) mutations in a cohort of Hungarian patients with CH.Patients: Eighty-five unrelated patients with permanent primary CH, all diagnosed at newborn screening, were selected.Main Outcome Measures: Coding exons of the TSHR gene were sequenced and evaluated together with the thyroid-specific clinical parameters. Functional features of the novel mutations were experimentally examined, and their comparative molecular models were built.Results: In four patients (one heterozygous and three compound heterozygous), seven TSHR mutations were identified. Among these, N432(1.50)D and P449(2.39)L are novel missense alterations. Importantly, the N432(1.50) residueis highly conserved among Gprotein-coupled receptors, and its function has not been examined yet in human glycoprotein hormone receptors. Our results indicate that the N432(1.50)D mutation disrupts important, architecture-stabilizing intramolecular interactions and ultimately leads to the complete intracellular retention of the receptor. On the other hand, P449(2.39) is located in the intracellular part of the receptor, which is important in G protein coupling. The P449(2.39L) mutation results in signaling impairment, with a more profound effect on the Gq/11 pathway.Conclusion: TSHR mutations are common among Hungarian patients with CH. The novel genetic alterations revealed an important structural role of the N432(1.50) and the P449(2.39) residues in receptor expression and signaling, respectively.