Acromesomelic dysplasia, type maroteaux caused by novel loss-of-function mutations of the NPR2 gene: Three case reports
Acromesomelic dysplasia, type maroteaux caused by novel loss-of-function mutations of the NPR2 gene: Three case reports
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DOI：
10.1002/ajmg.a.37463
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发表时间：
2016-02-01
影响因子：
2
通讯作者：
Cho, Tae-Joon
中科院分区：
文献类型：
--
作者：
Wang, Wei;Song, Mi Hyun;Cho, Tae-Joon
C型利钠肽（CNP）-利钠肽受体2（NPR 2）信号通路在软骨细胞发育中起重要作用。NPR 2基因的纯合性功能丧失突变可引起Maroteaux型肢端中肢发育不良（AMDM）。本研究的目的是鉴定和表征AMDM患者的NPR 2功能缺失突变。对三名韩国AMDM患者的NPR 2基因进行测序，并在体外对突变蛋白进行功能分析。在这三名患者中发现了五种新的NPR 2突变：两种复合杂合突变[患者1中的c.1231T>C（Tyr 411 His）和c.2761C>T（Arg 921 X），患者3中的c.1663A>T（Lys 555 X）和c.1711-1G>C（M571 VfsX 12）]和纯合突变[患者2中的c.2762G>A（Arg 921 Gln）]。与对照受试者相比，每例患者的血清NT-proCNP浓度显著升高。用CNP处理后，除患者3中发现的突变体外，用各突变体表达载体转染的细胞显示出可忽略不计或显著较低的cGMP应答。HA标记的野生型（wt）和HA突变体NPR 2以相当的水平表达：在wt和Arg 921 Gln中有两条约130和约120 kDa的条带，在Tyr 411 His中有一条约120 kDa的条带，在无义突变体中有一条约110 kDa的条带。关于亚细胞定位，Arg 921 Gln以及wt-NPR 2到达细胞表面，而Tyr 411 His和Arg 921 X突变体没有。Tyr 411 His和Arg 921 X NPR 2蛋白与内质网（ER）标记物共定位，并且未能从ER运输到高尔基体。这些结果与去糖基化实验一致。Tyr 411 His和Arg 921 X NPR 2是完全功能丧失突变，而Arg 921 Gln作为CNP的受体，功能有限。(c)2015 Wiley Periodicals，Inc.
The C-type natriuretic peptide (CNP)-natriuretic peptide receptor 2 (NPR2) signaling pathway plays an important role in chondrocyte development. Homozygous loss-of-function mutations of the NPR2 gene cause acromesomelic dysplasia, type Maroteaux (AMDM). The aim of this study was to identify and characterize NPR2 loss-of-function mutations in patients with AMDM. The NPR2 gene was sequenced in three Korean patients with AMDM and functional analysis of the mutated proteins was performed in vitro. Five novel NPR2 mutations were found in the three patients: two compound heterozygous mutations [c.1231T>C (Tyr411His) and c.2761C>T (Arg921X) in Patient 1 and c.1663A>T (Lys555X) and c.1711-1G>C (M571VfsX12) in Patient 3] and a homozygous mutation [c.2762G>A (Arg921Gln) in Patient 2]. Serum NT-proCNP concentration was significantly increased in each patient compared to control subjects. Cells transfected with the expression vector of each mutant except those found in Patient 3 showed a negligible or a markedly low cGMP response after treatment with CNP. HA-tagged wild-type (wt) and HA-mutant NPR2 were expressed at comparable levels: there were two bands of approximate to 130 and approximate to 120kDa in wt and Arg921Gln, a single approximate to 120kDa band in Tyr411His, and a single approximate to 110kDa in the nonsense mutant. With respect to subcellular localization, Arg921Gln as well as wt-NPR2 reached the cell surface, whereas Tyr411His and Arg921X mutants did not. The Tyr411His and Arg921X NPR2 proteins were co-localized with an endoplasmic reticulum (ER) marker and failed to traffic from the ER to the Golgi apparatus. These results are consistent with deglycosylation experiments. Tyr411His and Arg921X NPR2 are complete loss-of-function mutations, whereas Arg921Gln behaves as a receptor for CNP with limited function. (c) 2015 Wiley Periodicals, Inc.