School of Life Sciences, Central South University, Changsha, Hunan 410078, China.
Hunan Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan 410078, China.
Hum Mol Genet. 2023 May 5;32(10):1722-1729. doi: 10.1093/hmg/ddad014.
Isolated hypogonadotropic hypogonadism (IHH) is a rare disease with hypogonadism and infertility caused by the defects in embryonic migration of hypothalamic gonadotropin-releasing hormone (GnRH) neurons, hypothalamic GnRH secretion or GnRH signal transduction. PROKR2 gene, encoding a G-protein coupled receptor PROKR2, is one of the most frequently mutated genes identified in IHH patients. However, the functional consequences of several PROKR2 mutants remain elusive. In this study, we systematically analyzed the Gαq, Gαs and ERK1/2 signaling of 23 IHH-associated PROKR2 mutations which are yet to be functionally characterized. We demonstrate that blockage of Gαq, instead of MAPK/ERK pathway, inhibited PROK2-induced migration of PROKR2-expressing cells, implying that PROKR2-related IHH results primarily due to Gαq signaling pathway disruption. Combined with previous reports, we categorized a total of 63 IHH-associated PROKR2 mutations into four distinct groups according Gαq pathway functionality: (i) neutral (N, >80% activity); (ii) low pathogenicity (L, 50-80% activity); (iii) medium pathogenicity (M, 20-50% activity) and (iv) high pathogenicity (H, <20% activity). We further compared the cell-based functional results with in silico mutational prediction programs. Our results indicated that while Sorting Intolerant from Tolerant predictions were accurate for transmembrane region mutations, mutations localized in the intracellular and extracellular domains were accurately predicted by the Combined Annotation Dependent Depletion prediction tool. Our results thus provide a functional database that can be used to guide diagnosis and appropriate genetic counseling in IHH patients with PROKR2 mutations.
孤立性促性腺激素低下性性腺功能减退症（IHH）是一种罕见的疾病，其特征为促性腺激素释放激素（GnRH）神经元的胚胎迁移、下丘脑 GnRH 分泌或 GnRH 信号转导缺陷导致的性腺功能减退和不育。PROKR2 基因编码一种 G 蛋白偶联受体 PROKR2，是 IHH 患者中最常发现突变的基因之一。然而，几种 PROKR2 突变体的功能后果仍然难以捉摸。在这项研究中，我们系统地分析了 23 种尚未进行功能表征的与 IHH 相关的 PROKR2 突变体的 Gαq、Gαs 和 ERK1/2 信号转导。我们证明，阻断 Gαq 而非 MAPK/ERK 通路，抑制了表达 PROKR2 的细胞中 PROK2 诱导的迁移，这表明 PROKR2 相关的 IHH 主要是由于 Gαq 信号通路的破坏。结合以前的报告，我们根据 Gαq 通路的功能，将总共 63 种与 IHH 相关的 PROKR2 突变体分为四个不同的组：（i）中性（N，>80%活性）；（ii）低致病性（L，50-80%活性）；（iii）中等致病性（M，20-50%活性）和（iv）高致病性（H，<20%活性）。我们进一步将基于细胞的功能结果与基于计算的突变预测程序进行比较。我们的结果表明，虽然 Sorting Intolerant from Tolerant 预测对于跨膜区突变是准确的，但在细胞内和细胞外区域定位的突变则可由 Combined Annotation Dependent Depletion 预测工具准确预测。因此，我们的结果提供了一个功能数据库，可以用于指导 PROKR2 突变的 IHH 患者的诊断和适当的遗传咨询。
