A loss-of-function mutation in natriuretic peptide receptor 2 (Npr2) gene is responsible for disproportionate dwarfism in cn/cn mouse
A loss-of-function mutation in natriuretic peptide receptor 2 (Npr2) gene is responsible for disproportionate dwarfism in cn/cn mouse
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DOI：
10.1074/jbc.c500024200
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发表时间：
2005-04-08
影响因子：
4.8
通讯作者：
Kunieda, T
中科院分区：
文献类型：
--
作者：
Tsuji, T;Kunieda, T
软骨再生障碍小鼠是一种自发突变，其特征是在软骨内成骨过程中软骨生成受到干扰，导致四肢和尾巴不成比例的矮小。这些异常表型是由常染色体隐性基因(CN)控制的。在这项研究中，对115只受影响的F-2代小鼠进行了连锁分析，将CN基因定位在与4号染色体0.8-cM相似的区域，并将利钠肽受体2(Npr2)基因确定为该区域CN突变的最有效候选基因。该基因编码一种C型利钠肽(CNP)受体，在CNP与细胞外区域结合后，通过产生cGMP来积极调节纵向骨生长。对CN/CN小鼠Npr2基因的序列分析显示，在鸟氨酰环化酶区域，高度保守的Leu被Arg取代，导致T到G的颠倒。在CN/CN小鼠培养的软骨细胞中，CNP刺激对细胞内cGMP浓度无明显影响，而对+/+小鼠则明显升高。将突变的Npr2基因导入COS-7细胞也得到了类似的结果，表明CN/CN小鼠Npr2基因的错义突变导致了受体鸟酰环化酶活性的破坏。因此，我们认为CN/CN小鼠的矮小表型是由Npr2基因功能缺失突变引起的，CN/CN小鼠将是进一步研究CNP/利钠肽受体B信号调控软骨内成骨的分子机制的有用模型。
The achondroplastic mouse is a spontaneous mutant characterized by disproportionate dwarfism with short limbs and tail due to disturbed chondrogenesis during endochondral ossification. These abnormal phenotypes are controlled by an autosomal recessive gene (cn). In this study, linkage analysis using 115 affected mice of F-2 progeny mapped the cn locus on an similar to 0.8-cM region of chromosome 4, and natriuretic peptide receptor 2 (Npr2) gene was identified as the most potent candidate for the cn mutant in this region. This gene encodes a receptor for C-type natriuretic peptide (CNP) that positively regulates longitudinal bone growth by producing cGMP in response to CNP binding to the extracellular domain. Sequence analyses of the Npr2 gene in cn/cn mice revealed a T to G transversion leading to the amino acid substitution of highly conserved Leu with Arg in the guanylyl cyclase domain. In cultured chondrocytes of cn/cn mice, stimulus with CNP did not significantly increase intracellular cGMP concentration, whereas it increased in +/+ mice. Transfection of the mutant Npr2 gene into COS-7 cells also showed similar results, indicating that the missense mutation of the Npr2 gene in cn/cn mice resulted in disruption of the guanylyl cyclase activity of the receptor. We therefore concluded that the dwarf phenotype of cn/cn mouse is caused by a loss-of-function mutation of the Npr2 gene, and cn/cn mouse will be a useful model to further study the molecular mechanism regulating endochondral ossification by CNP/natriuretic peptide receptor B signal.