PROKR2 missense mutations associated with Kallmann syndrome impair receptor signalling activity
PROKR2 missense mutations associated with Kallmann syndrome impair receptor signalling activity
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DOI：
10.1093/hmg/ddn318
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发表时间：
2009-01-01
影响因子：
3.5
通讯作者：
Rondard, Philippe
中科院分区：
文献类型：
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作者：
Monnier, Carine;Dode, Catherine;Rondard, Philippe
卡尔曼综合征（Kallmann syndrome， KS）是由促性腺激素释放激素缺乏引起的性腺功能减退症，以及与嗅球形态发生缺陷有关的嗅觉缺失或低嗅觉症。在大量的KS患者中，在编码G蛋白偶联受体PROKR2 （PROKR2）的基因中发现了10种不同的错意突变（p.R85C、p.R85H、p.R164Q、p.L173R、p.W178S、p.r 210r、p.R268C、p.P290S、p.M323I、p.V331M），且多数为杂合状态。然而，在临床未受影响的个体中也发现了许多这些突变，从而提出了它们在KS表型中的实际含义的问题。我们在重组小鼠Prokr2中复制了这10个突变，并通过测量配体激活受体时细胞内钙的释放，测试了它们对转染HEK-293细胞信号活性的影响。我们发现除了一个突变受体（M323I）外，所有突变受体的信号活动都降低了。这些可以用不同的缺陷机制来解释。三个突变（L173R, W178S, P290S）破坏了受体的细胞表面靶向性。一个突变（Q210R）取消了配体结合。最后，5个突变（R85C、R85H、R164Q、R268C、V331M）可能破坏了受体的G蛋白偶联。此外，当野生型和突变型受体在HEK-293细胞中共表达时，保留在细胞内的突变受体均不影响野生型受体的细胞表面靶向，并且在质膜上适当定位的突变受体均不影响野生型受体的信号传导活性。这反驳了突变在体内的显性负面影响。
Kallmann syndrome (KS) combines hypogonadism due to gonadotropin-releasing hormone deficiency, and anosmia or hyposmia, related to defective olfactory bulb morphogenesis. In a large series of KS patients, ten different missense mutations (p.R85C, p.R85H, p.R164Q, p.L173R, p.W178S, p.Q210R, p.R268C, p.P290S, p.M323I, p.V331M) have been identified in the gene encoding the G protein-coupled receptor prokineticin receptor-2 (PROKR2), most often in the heterozygous state. Many of these mutations were, however, also found in clinically unaffected individuals, thus raising the question of their actual implication in the KS phenotype. We reproduced each of the ten mutations in a recombinant murine Prokr2, and tested their effects on the signalling activity in transfected HEK-293 cells, by measuring intracellular calcium release upon ligand-activation of the receptor. We found that all mutated receptors except one (M323I) had decreased signalling activities. These could be explained by different defective mechanisms. Three mutations (L173R, W178S, P290S) impaired cell surface-targeting of the receptor. One mutation (Q210R) abolished ligand-binding. Finally, five mutations (R85C, R85H, R164Q, R268C, V331M) presumably impaired G protein-coupling of the receptor. In addition, when wild-type and mutant receptors were coexpressed in HEK-293 cells, none of the mutant receptors that were retained within the cells did affect cell surface-targeting of the wild-type receptor, and none of the mutant receptors properly addressed at the plasma membrane did affect wild-type receptor signalling activity. This argues against a dominant negative effect of the mutations in vivo.